Carbohydrate pyrolysis mechanisms from isotopic labeling. Part 5. The pyrolysis of D-glucose: The origin of the light gases from the D-glucose molecule J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-12-07 John B. Paine, Yezdi B. Pithawalla, John D. Naworal
Flash pyrolysis in air of the complete set of 13C1 isotopologs of D-glucose, monitored by GC/MS using an efficient column for separating the light gases, allowed us to determine the sources within D-glucose for a range of light hydrocarbons and carbon oxides. These include carbon monoxide (CO), carbon dioxide (CO2), ethyne, ethene, ethane, propadiene, propene, propane, various isomers of butene, 1,3-butadiene, 1,3-cyclopentadiene and benzene. Inasmuch as the pyrolysis product was swept into the chromatographic column as formed, changes in isotopic incorporation with temperature rise could be qualitatively observed as changes of isotopic content across the chromatographic peak. There was significant divergence in labeled origin of CO and CO2, suggesting substantial mutual independence of formation. For both, however, composition was dominated by the first four carbons of D-glucose. The high-temperature range of formation of these may reflect the composition of the underlying char undergoing combustion. Similarities in isotopic content of ethene and ethane, or of allene, propylene and propane or of the various C4 species suggest that the least saturated versions are formed initially, and then undergo free-radical chain induced hydrogenation. Concerted electrocyclic fragmentations were invoked to explain the dominant formation of ethene, ethyne, propadiene and 1,3-butadiene. CO formation was postulated to arise in part from the fragmentation of glyoxal. CO and CO2 showed strong evidence of preferential ionization of the 13C isotopologs relative to the 12C ipsologs under our conditions, due to the magnetic isotope effect. Overlaid on this was a partial chromatographic enrichment of 13CO2 in the leading edge of the chromatographic peak. The data were normalized to adjust for both effects.
Catalytic fast pyrolysis of rice husk over hierarchical micro-mesoporous composite molecular sieve: Analytical Py-GC/MS study J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-12-07 Zhaoying Li, Zhaoping Zhong, Bo Zhang, Wei Wang, Weitao Wu
In order to promote efficient production of hydrocarbons, catalytic fast pyrolysis (CFP) of rice husk (RH) over catalysts is performed using Py-GC/MS. The catalyst is hierarchical micro-mesoporous composite molecular sieve prepared under different conditions including different concentrations (1.5 mol/L, 2.0 mol/L, 2.5 mol/L, 3.0 mol/L) of NaOH solution, different mass fraction of cetyltrimethylammonium bromide (CTAB) solution, different temperatures (90℃, 100℃, 110℃, 120℃) and durations (12 h, 24 h, 36 h). The fabricated hierarchical catalyst with HZSM-5 structure as the core and MCM-41 structure as the shell is characterized using N2 adsorption-desorption measurement and transmission electron microscopy. As the experimental results suggest, the highest value of total peak area of all the chemical compounds is obtained at 600℃. The fabricated hierarchical catalyst exhibit pronounced deoxygenation and excellent selectivity of aromatics. The maximum relative abundance of hydrocarbons (54%), maximum relative abundance of aromatics (39%) and value of selectivity of monocyclic aromatics (65%) are obtained by comparison with different hierarchical catalysts. Besides, the catalyzed transformation of large oxygenated compounds into hydrocarbons can be improved as a function of significant activation of hydrocarbon pool.
Production of phenols from pyrolysis of sugarcane bagasse lignin: Catalyst screening using thermogravimetric analysis - thermal desorption - gas chromatography - mass spectroscopy J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-12-08 D.R. Naron, F.X. Collard, L. Tyhoda, J.F. Görgens
The structural nature of lignin renders it suitable as a renewable source of phenolic compounds. The production of phenols from pyrolysis of sugarcane lignins with impregnated catalysts was investigated by screening of twelve catalysts (Al2O3, CaO, Fe2O3, TiO2, ZnO, MgO, CuO, MoO3, NiO, Ni/Al2O3-SiO2, NaOH, and KOH) at 1 wt.% content. Sugarcane bagasse lignins were isolated after soda-pulping (SD), soda-anthraquinone-pulping (SAQ) and steam explosion pre-treatment followed by enzymatic hydrolysis (SEH). Pyrolysis was conducted using a thermogravimetric analyser (TGA), and captured volatiles were quantified by thermal desorption (TD) gas chromatography-mass spectroscopy (GC-MS). The TGA results showed that the degradation profiles and char yields were influenced by the presence of catalysts, through modifications in conversion mechanisms. The highest increases in the total yield of phenols were obtained with KOH for SD lignin (+ 25.7%), CaO for SAQ lignin (+ 59.7%), and Fe2O3 for SEH lignin (+ 43.0%). Due to the enhancement of depolymerisation at low temperature (< 350 °C), the yields of syringol, guaiacol, and vinylguaiacol increased by 41%, 32%, and 43% for SD lignin, 121%, 93%, and 84% for SAQ lignin, and 72%, 77%, and 54% for SEH lignin respectively. These significant increases in the yields of phenols using 1 wt.% compared to ≥ 10 wt.% reported in literatures demonstrated the effectiveness of impregnation method.
Pyrolysis characteristics of ethanol swelling Shendong coal and the composition distribution of its coal tar J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-12-06 Ming Sun, Mingming Ma, Bo Lv, Qiuxiang Yao, Junwen Gao, Rucheng Wang, Yujuan Zhang, Xiaoxun Ma
The structural features and pyrolysis characteristics of Shendong demineralized coal (DC) and its ethanol swelling coal (EDSC) were investigated by Fourier transform infrared (FTIR), solid-state cross-polarization magic angle spinning carbon-13 nuclear magnetic resonance (CP/MAS 13C-NMR), thermo-gravimeter-Fourier transform infrared (TG-FTIR) spectroscopy, the self-made steel retort assay, and pyrolysis gas chromatography-mass spectrometer (Py-GC/MS). The pyrolysis product coal tar from the self-made steel retort assay was extracted by n-hexane to obtain the n-hexane solubles (CTHS) as well as the n-hexane insolubles (CTHIS). The composition of CTHS has been explored by the analysis of GC/MS, and CTHIS was investigated by the analyses of TG-FTIR and Py-GC/MS. The analysis data display that the coal tar yield of EDSC increases by 0.42 wt% and the semi-coke yield of EDSC decreases by 1.33 wt%. The intensity of -OH stretching vibration at 3405 cm-1 in the FTIR spectra of EDSC is weakened and the peak moves to the low wave number. Aliphatic carbons and aromatic carbons of EDSC decrease. The content of neutral compounds in EDSC pyrolysis tar increases by 2.01 wt%. CTHIS mainly includes phenols, alkanes, aromatics and pyridine. Phenolic compounds and nitrogen-containing heterocyclic compounds in the pyrolysis volatiles of EDSC-CTHIS increase by 1.12 wt% and 1.46 wt%, respectively.
Pyrolysis Pathway Redirection of HNIW by Nano-Aluminum J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-12-06 Honglei Zhang, Qingjie Jiao, Yapeng Ou, Xueyong Guo
The pyrolysis behavior of hexanitrohexaazaisowurtzitane (HNIW) and HNIW/nano-Aluminum are investigated by non-isothermal differential scanning calorimetry/thermogravimetry/Pyrolysis-mass spectrometry/Fourier transform infrared spectroscopy (DSC/TG/Py-MS/FTIR) coupling analysis. The result shows that nano-Al improves the thermal stability of HNIW by swinging the very beginning of pyrolysis from synchronous bond cleavage of the highly strained molecular to the formation of HONO free radical corresponding with the increment of apparent activation energy. After the initial stage, nano-Al catalyzes the pyrolysis pathway to primary cleavage of C-N bond and releasing hyperbaric unstable N2O, which sequentially reacts with other gaseous products and Al.
The dehydration of MgCl2·6H2O by inhibition of hydrolysis and conversion of hydrolysate J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-12-07 Zhimin Zhang, Xuchen Lu, Yan Yan, Tizhuang Wang
The hydrolysis of magnesium chloride hexahydrate and the countermeasures against hydrolysis were investigated. X-ray diffraction, TG-DSC analysis, and chemical analysis were employed to characterize the hydrolysis process, and then the hydrolysis reactions occurred at different temperatures were determined. After that, the combination of inhibition of hydrolysis and conversion of hydrolysate was adopted to cope with the different hydrolysis reactions. The hydrolysis process of MgCl2·6H2O includes the hydrolysis of dehydrated magnesium chloride below 300 °C with MgOHCl·xH2O as hydrolysate and the hydrolysis of anhydrous MgCl2 over 400 °C with MgO as hydrolysate. The inhibition of hydrolysis by forming dehydrated ammonium carnallite (below 300 °C) and the conversion of hydrolysate (above 400 °C) can effectively resolve the hydrolysis problem occurred at different stages. The dimension of the mixture of MgCl2·6H2O and NH4Cl influences the mass transfer and reaction process. When the ratio of height to diameter of the mixture was over 9:1, the magnesia content in anhydrous MgCl2 reached 0.1 wt.%.
Enhancement of bio-oil quality: metal-induced microwave-assisted pyrolysis coupled with ex-situ catalytic upgrading over HZSM-5 J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-12-04 Jing Sun, Ke Wang, Zhanlong Song, Yuting Lv, Shouyan Chen
Metal-induced microwave-assisted pyrolysis followed by ex-situ catalytic upgrading of vapors using a packed HZSM-5 bed was designed and investigated for the production of upgraded bio-oil from peanut shells. Effects of the pyrolysis method, catalyst bed temperature, and microwave power on both the product yield and the chemical composition of bio-oil were investigated. Results showed that compared with conventional pyrolysis, microwave-metal-assisted pyrolysis promoted the yield of aromatic hydrocarbons, which could be further enhanced by applying ex situ HZSM-5 bed. The catalyst bed temperature has a significant effect on the product yield, bio-oil chemical profile and coke deposits on catalyst. The bio-oil yield reached its maximum value (5.6 wt.%) at 600 °C, with the proportion of oxygen-free hydrocarbons of 67% and coke deposits of 0.6%. With the further increase of temperature to 700 °C, the proportion of oxygen-free hydrocarbons increased to 77%, that of coke deposits decreased to 0.5%, and that of the bio-oil yield decreased to 4.7 wt.%. Besides the catalyst bed temperature, higher microwave power led to higher bio-oil yield; however, the proportion of oxygen-free components decreased slightly owing to the reduction in contact time. Considering the outstanding performance in bio-oil deoxygenation, this work provides an important reference for bio-oil upgrading technology development.
On-line photoionization mass spectrometric study of lignin and lignite co-pyrolysis: insight into the synergetic effect J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-12-04 Zhongyue Zhou, Chunjiang Liu, Xiamin Chen, Hao Ma, Chaoqun Zhou, Yizun Wang, Fei Qi
Co-pyrolysis behavior of kraft lignin (KL) and lignite (LI) was studied by thermogravimetry (TG) combined with on-line photoionization time-of-flight mass spectrometry (PI-TOF-MS) to get insights into the synergetic effect on the total yield and detailed composition of volatile. Significant synergetic effect was observed between KL and LI during co-pyrolysis processes, especially near the temperature with maximum weight loss rate. The interactions of typical co-pyrolysis products were figured out via the real-time and online mass spectrometry and was evaluated by comparing the experimental value with the calculated theoretical value. The results showed that the synergetic effect was beneficial to enhance the production of volatile and decrease the total yield of char. The interaction on typical co-pyrolysis products was further discussed. The result may provide useful guidance for the practical co-conversion of biomass and low-rank coal.
Py-GC/MS analysis on product distribution of two-staged biomass pyrolysis J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-12-04 Wenwen Cai, Qian Liu, Dekui Shen, Jingzhen Wang
Based on the difference in thermal stability and product distribution of the three main components, the two-staged pyrolysis of biomass was proposed as a new method, by which the liquid products would be less diverse and more concentrated, and beneficial to further upgrading or extracting chemicals. Rice straw, cedar wood and dalbergia wood were selected as the representative biomass materials. TG-FTIR analysis of biomass and the three main components was firstly carried out. According to the pyrolysis characteristics and the volatile release processes, 270-360 °C was selected as the optional temperature range for the low-temperature stage of the two-staged pyrolysis. Then the two-staged pyrolysis of three different biomasses was performed by using Py-GC/MS, with the first stage at 270 °C, 320 °C or 360 °C and then the second stage at 550 °C, compared with the direct pyrolysis at 550 °C. It was indicated that the two-staged pyrolysis could efficiently separate biomass pyrolysis products, especially the enrichment of organic acids, alcohols and aldehydes in the first stage, and the enrichment of phenolic substances in the second stage. The optimum temperature of the first stage was 320 °C, which was suitable for three different kinds of biomass.
In-situ evaluation for upgrading of biomass over noble metal catalysts by isotopic tracing and NMR monitoring J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-12-04 Haoxi Ben, Zhihong Wu, Guangting Han, Wei Jiang, Arthur Ragauskas
One of the key challenges in studying the upgrading processes for the conversion of biomass is developing an understanding of the underlying conversion mechanism at the atomic scale. This study proposed an innovative high pressure in situ NMR monitoring approach for an isotopic traced upgrading process, which demonstrated a powerful capability to identify key products and provide insights into the reaction structure. The investigations for ring opening of two basic model compounds – methylcyclopentane (MCP) and cyclohexane (CH) on Ir, Pt, Ru and Pd/γ-Al2O3 at 55 and 110 °C have been accomplished. For the study performed at 110 °C on Ir, Pt and Ru catalysts, the trend of H/D exchange rates were clearly dependent on the position on the ring with the highest exchange rate for the unhindered (or open side) and the lowest rate with the methyl group. However, Pd could perform almost equally efficient H/D exchanges for all sides, which may indicate that the “turnover” reactions could also occur on Pd. For both MCP and CH, Ru performed the most efficient H/D exchanges (C-H bond activation), and ring opened products were only observed with the Ru catalyst at 110 °C suggesting it is the most promising ring opening catalyst.
Catalytic degradation of linear low-density polyethylene over hy-zeolite via pre-degradation method J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-12-04 Ishaka Muhammad, Nura Makwashi, George Manos
The catalytic degradation of linear low-density (lldPE) polyethylene over HY-zeolite catalyst was studied in a semi-batch reactor. One of the important problems encountered during catalytic pyrolysis of macromolecules is the contact with the catalyst, which is known to affect the product distribution and the quality of the coke formed. A pre-degradation procedure was introduced to achieve efficient contact between the LLDPE macromolecules and the catalyst. The influence of the pre-degradation to the reaction conditions including holding time, temperature, polymer to catalyst ratio and flow rate of carrier gas was examined. Moreover, the pre-degradation results were compared with the results obtained using normal mixing procedure. The results obtained showed that, pre-degradation promotes the liquid fraction by a factor of more than one-fold increase at the expense of the gas fraction and the coke yield. The optimal liquid fraction with pre-degradation was obtained at low reaction temperature and catalyst amount respectively, i.e. high polymer to catalyst ratio, making it economically viable method for the degradation of lldPE. The coke content was analysed using TGA in nitrogen atmosphere to remove the soft coke and then in air isothermally at the final temperature to burn the hard coke. The TGA results of the coked sample show less concentration of coke components on the catalyst using the pre-degradation method as compared to the normal mixing which shows high concentration of coke components especially at low reaction temperature. Moreover, the majority of the coke components produced using the pre-degradation method were soft coke, making it more efficient for the re-usability of the catalyst. The liquid samples collected were analysed using gas chromatography and the products distribution were presented in the form of boiling point distribution curves. The bulk of the liquid products produced were lighter fractions with a peak around the gasoline range.
Conversion of lignin into light olefins and aromatics over Fe/ZSM-5 catalytic fast pyrolysis: Significance of Fe contents and temperature J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-12-03 Mingfa Yang, Jingai Shao, Zixu Yang, Haiping Yang, Xianhua Wang, Zhengshun Wu, Hanping Chen
The conversion of lignin into light olefins and aromatic compounds via catalytic fast pyrolysis was performed in a fixed bed reactor over a range of Fe-modified ZSM-5 catalysts at different temperatures. More specifically, catalysts containing 0, 1, 3, 6, and 9 wt.% Fe were prepared by an impregnation method, and the resulting catalysts were characterized by XRD, NH3-TPD, H2-TPR and BET analysis. The catalyst structure remained intact upon increasing the Fe loading, although the surface area, pore volume, and number of acidic sites of the catalysts varied, and the total acidity increased upon increasing the Fe loading. The maximum carbon yield of light olefins plus aromatic compounds was 12.8%, and this was obtained with a 3 wt.% Fe loading at 600 °C. This yield decreased upon further increasing the Fe loading and upon increasing the temperature to 700 °C. Moreover, the selectivity of C2H4 was more than 80%, and it was decreased with the Fe loading and increased with temperature increasing. The total acidity had a direct relationship with aromatic production, while light olefins were mainly affected by medium acid sites.
Catalytic pyrolysis over transition metal-modified zeolites: a comparative study between catalyst activity and deactivation J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-12-04 H. Persson, I. Duman, S. Wang, L.J. Pettersson, W. Yang
The utilization of metal-doped zeolites in catalytic pyrolysis of biomass is a well-known approach to promote the formation of certain compounds. One major technical issue of using zeolites in biomass pyrolysis processes is their rapid deactivation due to coke formation. However, little is known about how metal-doping influences the characteristics of coking, such as coking rate and its composition.In this study, four different materials were experimentally evaluated based on their catalytic activity and coking characteristics: HZSM-5, Fe/ZSM-5, Ni/ZSM-5 and FeNi/ZSM-5. The materials were prepared and characterized followed by screening in a bench-scale setup for in-situ catalytic pyrolysis. The mass balance and composition of pyrolysis products including catalyst coke were analyzed.It was found that metal-doping increases the concentration of aromatic hydrocarbons in the liquid product from 59.0 to 82.8 % of GC/MS peak area, especially monoaromatic hydrocarbons (MAHs) and naphthalenes. Fe mainly promotes MAHs whereas Ni additionally promotes naphthalenes. FeNi/ZSM-5 enhances the production of both compound groups as well as further reducing the total acid number (TAN). Regarding the catalyst coke, metal-doped catalysts present an increased concentration of aromatic hydrocarbons in terms of MAHs, naphthalenes and polyaromatic hydrocarbons. For each catalyst, the chemical composition of catalyst coke reflects the catalyst’s activity seen in vapor upgrading. A reaction pathway based on the observed catalyst activities of metal-doped ZSM-5 and HZSM-5 is proposed.The results also show that metal-doping of catalysts increases the formation of catalyst coke, mainly due to a higher concentration of strong acid sites. Also, the rate of coking is dependent on the strength of acid sites, where the strength correlates with the severity of coking. The coke yield was seen to increase from 3.5 wt% in the case of HZSM-5 to maximum 7.2 wt% over Fe/ZSM-5. However, the metal-doping of catalysts reduces the temperature of catalyst regeneration and catalyzes the oxidation of coke. Overall, this work presents a comparative study between catalyst activity and deactivation during thermochemical conversion of biomass.
Slow pyrolysis of xylan as pentose model compound for hardwood hemicellulose: a study of the catalytic effect of Na ions J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-12-04 P. Giudicianni, V. Gargiulo, M. Alfè, R. Ragucci, A.I. Ferreiro, M. Rabaçal, M. Costa
In this study, the effect of sodium (Na) ions on the slow pyrolysis of hemicellulose is assessed using xylan as a representative of hardwood hemicellulose. Thermogravimetric analysis and pyrolysis tests were conducted at slow heating rates (5 K/min) up to 973 K on commercial xylan, demineralized xylan and Na+ doped xylan samples. Commercial xylan was demineralized by using a cation-exchange resin to reduce the presence of inherent inorganics (mainly alkali or alkaline-earth metals). Subsequently, the demineralized xylan was doped with controlled amounts of Na ions (0.4, 0.5 and 1.1 wt.%) by using cation-exchange resin in Na+ form. The pyrolysis products yields (gas, liquid and char) and the composition of the gas mixture were quantified for each sample. Gas chromatography/mass spectrometry (GC/MS) analysis were performed to quantify the main species in the liquid products. The results, discussed considering of the available hemicellulose pyrolysis models, demonstrate that the presence of Na+ greatly affects the pyrolytic behavior of the samples, whereas only slight quantitative effects are observed on the solid residues yields, which increase with Na+ concentration. Furthermore, Na+ favors the ring opening reactions (increasing the production of CO2, CO and hydroxy ketones) and the rearrangement of the xylose ring to form furan derivatives. The reaction pathways competing with 2-furaldehyde production mechanism could explain the non-monotonous trend of this compound as function of Na+ content.
Comparison of microwave and conventional heating methods for the thermal decomposition of pyrite under different heating temperatures J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-12-03 Xiaoliang Zhang, Jue Kou, Chunbao Sun
The thermal decomposition of pyrite is usually considered to play an important role in the pyrolysis of coal as well as the pretreatment of gold-bearing sulfides concentrates. This study focuses on the influences of microwave and conventional heating methods for the thermal decomposition of pyrite on the sulfur transformation, the development of phase transformation, surface morphology and elemental distribution in an inert atmosphere. Results show that the rapid decomposition of pyrite is easy to realize with microwave heating. Compared to conventional heating, microwave heating effectively shortened the heating time and promoted sulfur transformation. It was also observed that the phase transformation occurred at the temperature range of 600–700 °C under conventional heating, whereas the phase transition temperature was reduced to the range of 500–600 °C under microwave heating. This phenomenon implied that microwave heating lowered the thermal decomposition temperature of pyrite. Moreover, kinetic analysis also indicated that the activation energy of pyrite thermal decomposition was lowered from 199.76 kJ·mol-1 to 172.62 kJ·mol-1 under microwave heating. The SEM and EDS results indicate the differences between conventional and microwave heating can be attributed to the heat transfer process. Although the final surface morphology of the pyrite samples at 700 °C was both loose and porous no matter which heating methods were adopted, microwave heating resulted in more porous structures at a lower temperature with a shorter duration of time.
Effect of calcium on the secondary reactions of tar from Zhundong coal pyrolysis: A molecular dynamics simulation using ReaxFF J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-11-30 Dikun Hong, Zheng Cao, Xin Guo
In this paper, molecular dynamics method based on reactive force field is used to investigate the effect of calcium on the secondary reactions of nascent tar from Zhundong coal pyrolysis. The coal with and without Ca species are pyrolyzed at various temperatures. The results show that Ca rarely affects the primary pyrolysis of coal, but significantly promotes the secondary reactions of tar, hence resulting in the increase of gas and char yields. By extracting the tar radical fragments from coal primary pyrolysis products, the nascent tar systems with and without Ca species are constructed respectively. Simulations on these two tar systems are carried out at various temperatures ranging from 1800 K to 3000 K. The results show that very little amounts of gas-Ca and atomic Ca are observed at low temperatures. Ca is mainly involved in a repeated bond-breaking and bond-forming process between tar and coke. Ca species only promotes the polymerization of tar at the low temperatures. While at high temperatures, a large amount of Ca is released in the form of atom, which will recombine with tar radicals and thus promoting the polymerization of tar. In the meanwhile, the atomic Ca will also attack the tar fragments and enhance the cracking of tar. The activation energies of tar polymerization and cracking reactions are calculated as 26.6 and 20.3 kcal/mol in the absence of Ca, compared to 19.7 and 20.1 kcal/mol in the presence of Ca. This means that the role of Ca in reducing the activation energy for tar polymerization is much more significant than that for tar cracking reactions.
Liquid phase pyrolysis of wheat straw and poplar in hexadecane solvent J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-11-30 Blanka Szabó, Márton Takács, Attila Domján, Eszter Barta-Rajnai, József Valyon, Jenő Hancsók, Róbert Barthos
There is a need for replacement of fuel, especially transportation fuel, obtained from fossil resources by bio-based alternative. The thermochemical conversion is a feasible method to degrade and partially deoxygenate the natural resource lignocellulose to get bio-oils as fuel precursors. The present paper describes the liquid phase pyrolysis of wheat straw and poplar under inert atmosphere in n-hexadecane solvent. An autoclave batch reactor system was used. The influence of reaction temperature, residence time, solvent/biomass ratio and the effect of solid acid and base catalysts on the product distribution and yields were investigated. The reaction products were analyzed by means of CHNO elemental analysis, Solid Phase Micro Extraction-Gas Chromatograpy-Mass Spectroscopy (SPME-GC-MS), 1H and 13C-Nuclear Magnetic Resonance (NMR) spectroscopies. About 40-49 wt% of lignocellulosic carbon was successfully transferred to hexadecane. The best carbon yields were achieved at 350 °C. The main extracted products were alkyl and alkoxy derivatives of phenol and furan derivatives. By comparing seven parallel experiments in presence and absence of the catalysts no or only negligible catalytic effect was observed. The effect of heterogeneous catalysts was manifested only in splitting the primarily extracted macromolecules. The carbon/oxygen mass balances suggest that the extracted compounds have relatively high residual oxygen content.
Thermal desorption and characterization of carbonaceous deposits in Mo/HZSM-5 catalyst J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-11-30 Ganesh Sanapur, Arun Kumar, Amit Mondal, Sivakumar Sreeramagiri, Rajeshwer Dongara
Mo/HZSM-5 is the most active catalyst for dehydroaromatization of methane to benzene reaction. In this process, coking is the major problem to develop technically and economically successful process, as the catalyst gets deactivated due to blocking of active sites, pores and cavities, resulting in site poisoning. Hence, detailed information on the nature of the coke, its structure and composition are important factors to understand the performance of the catalyst. In the present paper, we present characterization of carbonaceous deposits formed on the surface of Mo/HZSM-5 catalyst using multi analytical techniques such as TDS-GC-MS, TGA, CHN and TEM. Investigated the structures of soft coke species using N2, and H2 temperature programmed desorption by applying in-house designed micro reactor for coke desorption from spent catalyst, followed by detailed composition analysis by TDS-GC-MS technique. The thermal desorption GC-MS method has advantages over the existing solvent extraction methods, in terms of sensitivity, overall analysis time and sample quantity requirements for complete studies. Additionally, this setup provides flexibility to understand the regeneration mechanism of catalyst under various environment and temperature conditions. The new in-house setup has given useful insights into structures of coke components and possible regeneration protocols.
Thermal pretreatment of a high lignin SSF digester residue to increase its softening point J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2016-03-24 Daniel Howe, Manuel Garcia-Perez, Danny Taasevigen, James Rainbolt, Karl Albrecht, Hui Li, Liqing Wei, Armando McDonald, Michael Wolcott
Residues high in lignin and ash generated from the simultaneous saccharification and fermentation of corn stover were thermally pretreated in an inert (N2) atmosphere to study the effect of time and temperature on their softening points. These residues are difficult to feed into gasifiers due to premature thermal degradation and formation of reactive liquids in the feed lines, leading to plugging. The untreated and treated residues were characterized by proximate and ultimate analysis, and then analyzed via TGA, DSC, 13C NMR, Py-GC–MS, CHNO/S, and TMA. Interpretation of the compositional analysis indicates that the weight loss observed during pretreatment is mainly due to the thermal decomposition and volatilization of the hemicelluloses and amorphous cellulose fractions. Fixed carbon increases in the pretreated material, mostly due to a concentration effect rather than the formation of new extra poly-aromatic material. The optimal processing time and temperature to minimize the production of carbonyl groups in the pretreated samples was 300 °C at a time of 30 min. Results showed that the softening point of the material could be increased from 187 °C to 250 °C, and that under the experimental conditions studied, pretreatment temperature plays a more important role than time. The increase in softening point was mainly due to the formation of covalent bonds in the lignin structures and the removal of low molecular weight volatile intermediates.
Adventures in pyrolysis II, modeling pyrolysis peaks of petroleum source rocks J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-08-08 Richard J. Drozd
Programmed pyrolysis is an integral part petroleum source rock evaluation. The analysis is used to determine the potential of a source rock to generate further petroleum, and with other geochemical measurements, how much it may have generated in the past. An important part of the overall evaluation is an estimate of the source rock thermal maturity. Unfortunately, the addition of any extraneous, non-native hydrocarbons can negatively impact the yield of the samples, and more important, the thermal maturity determination. These extraneous hydrocarbons can be petroleum previously generated and retained within the source rock, fluids that migrated in the subsurface into the rocks, or organic material added during the drilling process. The objective of this study was to determine if mathematical methods could be used to remove these extraneous contributions from the true source rock yields, and arrive at a better determination of thermal maturity.Eighteen samples were studies using the standard pyrolysis method applied in the geochemical services industry. Two aliquots of each sample were analyzed: one as-received and a second after solvent extraction solvents to remove soluble organic matter but not kerogen. The pyrograms typically associate with the conversion of native organic matter in the rock were considered as the sum of up to three underlying components which could be recovered by non-linear least squares methods. Four distribution functions were used to model the pyrograms: classical Gaussian distribution, the Cauchy function, the Logistic function and the Weibull distribution. In addition to the ability of each model to match the measured data, each was evaluated for ease of use. All models reproduced the total pyrolysis yields of the test samples, and generated Tmax values with agreed within 2 °C.•The Gaussian model was marginally better at fitting the measurements than the Logistic or Weibull models, and distinctly better than the Cauchy model. Based upon experience, the Gaussian model was the most forgiving in the choice of initial parameters.•The Cauchy model performed the poorest at fitting the measurements and had the largest differences between extracted and unextracted Tmax values. The deviations from the measured values were most pronounced at high and low temperatures due the longer tail of the Cauchy function.•The Logistic model has marginally lower ability to fit the measured data than the Gaussian model, and similar to the Weibull model. However, the Logistic model was more sensitive to the choice of initial values than the Gaussian model, but less sensitive than the Weibull model.•The Weibull model was marginally poorer at fitting the measurements than the Gaussian model and similar to the Logistic model. It did less well at fitting the four component model for the more complex samples. It was most sensitive to the accurate choices for the initial conditions to insure convergence. For some samples sequential manual choices for these parameters was needed before the Gauss-Newton method could be employed.
Combined direct analysis in real-time mass spectrometry (DART-MS) with analytical pyrolysis for characterization of Chinese crude propolis J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-11-28 Yilei Huang, Zhongping Huang, Chuichi Watanabe, Lili Wang
A combination of direct analysis in real-time mass spectrometry (DART-MS) with analytical pyrolysis comprising evolved gas analysis-mass spectrometry (EGA-MS) and heart-cut EGA-gas chromatography (GC)/MS was used for characterization of Chinese crude propolis samples. DART-MS allowed us to profile general whole chemical components in propolis including terpenoids, phenolic acids and esters, flavonoid aglycones, flavonoid glycosides, phenolic glycerides and hydrocarbons with their molecular weights in the range of 100 – 800. EGA-MS was used to investigate the thermal behaviors of main components observed by DART-MS. The results revealed three temperature zones for the releasing behaviors of main constituents: (1) vaporization of terpenoids within 120 – 160 °C, (2) vaporization of phenolic acids and flavonoid aglycones, and pyrolysis of some flavonoid glycosides and beeswax within 160 – 300 °C, (3) pyrolysis of some flavonoid glycosides, phenolic glycerides and beeswax within 300 – 550 °C. Based on extracted ion thermograms of flavonoids, it is clear that chrysin and tectochrysin existed only as aglycones, while pinocembrin, galangin, 2’, 6’-dihydroxy-4’-methoxychalcone and naringenin existed as both aglycones and glycosides. According to temperature zones, heart-cut EGA GC/MS data clearly indicated that 43 components were identified for 3 crude propolis samples collected from different origins, and grouped into 7 classes: alcohols/phenols, aldehydes/ketones, terpenoids, phenolic acids and esters, flavonoids, hydrocarbons and others. Among them, terpenoids, phenolic acids and esters, and flavonoids were main bioactive classes. Terpenoids accounted for 43.5 – 82.1 % in zone A, and flavonoids accounted for 3.7 – 23.9 % in zone B and 5.2 – 46.5 % in zone C, showing their different origins. In addition, flavonoid aglycones and their glycosides also could be semiquantitatively analyzed separately by analytical pyrolysis techniques used. Flavonoid aglycones accounted for a majority of total flavonoids with its proportions more than 52.6 – 66.7 % in propolis samples. All the obtained results demonstrate that the combination of these methods is effective for profiling all main components in Chinese crude propolis.
Influence of step duration in fractionated Py-GC/MS of lignocellulosic biomass J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-11-27 M. González Martínez, T. Ohra-aho, D da Silva Perez, T. Tamminen, C. Dupont
Fractionated pyrolysis coupled to gas chromatography and mass spectrometry (Py-GC/MS) appears as an interesting analytical tool for elucidating lignocellulosic biomass structure, as it allows the progressive release of chemical fragments representative of biomass macromolecular composition. In this paper the effect of fractionated pyrolysis time (from 5 s to 300 s) on the degradation of lignin and carbohydrates from beech wood was studied at temperatures between 250 °C and 500 °C. Fractionated Py-GC/MS showed that the release temperature of the volatile degradation products varied between the volatile species detected. In addition, the step duration time changed the thermal degradation behavior of lignocellulosic components. Shortening the constant step duration time from 300 s to 5 s shifted the maximum weight loss to the higher temperatures. The result was opposite at long step duration times. Time optimization at each pyrolysis temperature (250 °C, 40 s; 300 °C, 30 s; 350 °C, 25 s; 370 °C, 20 s; 400 °C, 15 s; 450 °C, 10 s; 500 °C, 5 s) enhanced the yield of both lignin and carbohydrate volatile pyrolysis degradation products. In addition, two multiple temperature maxima were shown for some lignin and carbohydrate derivatives. This behavior may be due to the two different pathways of formation and macromolecular origins of compounds in beech wood. At optimized conditions lignin derivatives having a 3-carbon side chain substituent had a maximum at lower temperature than that of lignin derivatives with a 1-carbon side chain substituent. That phenomenon follows the order of primary and secondary pyrolysis reactions. Similar behaviors were observed among the degradation products of hemicelluloses and cellulose. Degradation products of hemicelluloses were mainly released at lower temperatures than those of cellulose derivatives, which illustrates the lower thermal stability of hemicelluloses compared to cellulose.
Effects of interactions between corncob volatiles and lignite on their products during rapid co-pyrolysis J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-11-26 Dong Yan, Jiang Guo, Meijun Wang, Jilin Tian, Jiao Kong, Yongfeng Hu, Liping Chang
The interactions of corncob volatiles and lignite in the process of rapid co-pyrolysis and the effects on their product distributions and properties were examined for the efficient co-utilization of biomass and lignite. A novel two-stage, three-tube reactor was used to do co-pyrolysis experiments, which allowed the verification of interactions occurred only between corncob volatile and lignite. Raw corncob and its demineralized sample were employed for studying the different interactions of organic radical fragments and AAEMs in corncob volatiles on lignite. It was found that the interactions resulted in the decreased liquid yields but increased gas yields, and varied oxidative reactivity of lignite char by changing its chemical structure. There exist different effects on product distribution and property for organic radical fragments and AAEMs in corncob volatiles. The former could promote the interaction of nascent char-volatiles and accelerate the stabilization of radical fragments, the latter mainly catalyzed the decomposition reaction of corncob matrix below 700 °C, while mainly volatilized and catalyzed the reactions between volatiles in gaseous phase when the temperature was above 700 °C.
Carbothermal reactions of tobelite with coal char at high temperatures under N2 atmosphere J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-11-26 Huirong Zhang, Jin Bai, Wen Li, Fangqin Cheng
The main aim of this investigation is to present a comprehensive analysis of carbothermal reactions with tobelite at high temperatures under N2. The mixtures with mass ratios of demineralized coal: tobelite = 1:3, 1:5, 1:7, 1:9 were subjected to thermogravimetric analysis (TGA) up to 1500 °C, the mineral composition and morphology of the product after carbothermal reaction were evaluated by X-ray diffraction (XRD) and scanning electron microscope with energy dispersive spectroscopy (SEM-EDS). FactSage equilibrium calculations also used for predicting mineral transformation process. It was found that thermal transformation of the tobelite in demineralized coal includes four stages: stage I (0–200 °C), stage II (200–900 °C), stage III (900–1200 °C), stage IV (1200–1500 °C). The processes of coal devolatilization and tobelite decomposition are independent processes when the temperature is below 1000 °C, the contact mode among minerals and coal matrix affect the thermal behavior of minerals. The carbothermal reactions start at 1200 °C. When coal: tobelite = 3:7, the products include incompletely reacted Al6Si2O13 (mullite), Al2O3, SiC, β-Si3N4 and Al6Si6N8O9; When coal: tobelite = 5:5, the reaction products include SiAl6O2N, Al2O3 and SiC, Al2O3 and SiC are the main phases; When coal: tobelite = 7:3, the composition is Si6AlO6N5, AlN, SiC and SiO2, SiC and AlN are the main phases. Carbon structure may strongly influence the carbothermal reaction. In addition, the formation and disappearance of SiC could releases CO by reaction with carbon during the carbothermal reaction, thus promoting char gasification.
Mobile demonstration unit for fast- and catalytic pyrolysis: The Combustion Reduction Integrated Pyrolysis System (CRIPS) J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-11-22 Akwasi A. Boateng, Mark A. Schaffer, Charles A. Mullen, Neil M. Goldberg
A mobile pyrolysis unit, designed to process biomass at a rate of 83.3 kg h-1 (two metric tons per day, MTPD) has been developed, constructed and demonstrated operation for on-farm or in-forest production of pyrolysis oil (bio-oil). The trailer-mounted pyrolysis apparatus is based on the combustion reduction integrated pyrolysis system (CRIPS), a patented, dual fluidized bed, biomass pyrolysis design developed by USDA and the University of Pretoria. The mobile design goal was to demonstrate efficacy of on-farm production and coordinate station-to-station operation to simulate a collective system of several unit operations within a distributed/satellite system of pyrolysis biorefinery. Key design features that provide utility for remote operations including in-situ (on-trailer) generation of heat and electric power required for self-sufficiency were tested at this scale. Extensive trials on three feedstocks important to US agriculture, namely woody biomass, switchgrass and horse litter, were conducted. The results show that a processing rate of up to 40 kg h-1 (approximately 1 MTPD) was successful and easily achievable for the said biomass on the trailer; beyond which, however, operational problems such as pressure imbalance between the dual-bed reactors were encountered, hampering process control. The operation of the CRIPS under catalytic pyrolysis was even more successful with catalyst regeneration readily achievable with the design. Bio-oil yield for neat/traditional and catalytic pyrolysis were in the 45% and 5-10% ranges respectively, similar to lab scale, demonstrating production of large volumes of bio-oil on-farm. Bio-oil quality for catalytic pyrolysis was consistent over several hours on stream due to continuous catalyst regeneration that the design affords yielding high levels of BTEX compounds; however, deactivation due to alkali contamination was noticeable at cumulative biomass to catalyst ratios of > 6/1. Compared with laboratory scale results, non-catalytic pyrolysis product quality for the demonstration scale wavered between that of regular pyrolysis oil produced under nitrogen atmosphere and that of the tail-gas reactive pyrolysis (TGRP) as partial recycle of effluent gas was possible with the mounted CRIPS design. With successful demonstration at 1 MTPD capacity the mobile system meets the technology readiness level for pre-commercial design suggested for blueprints (i.e. development of full-scale prototype), however more testing is underway to remove the bottlenecks impeding operation at the full-scale design.
Application of Nitrogen-based Blowing Agents as an Additive in Pyrolysis of Cellulose J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-11-22 Evan Terrell, Manuel Garcia-Perez
Pyrolysis of cellulose mixed with blowing agent additives containing high nitrogen content has been investigated in this work. The additives used are dicyandiamide (DCD), 5-aminotetrazole (5AT) and 5-phenyl-1H-tetrazole (5PT), in concentrations of 0.25, 0.50, 1.0, 2.0 and 4.0% (weight). Blowing agents are of particular interest as a cellulose pyrolysis additive for two reasons: as a first case, if these additives and their decomposition products are chemically inert with respect to cellulose pyrolysis reactions, then they can serve to enhance the ejection of high-molecular weight aerosols from the liquid intermediate phase that is known to form during pyrolysis; as a second case, if these additives are not chemically inert, then the reactions between blowing agent decomposition products (e.g., NH3 and HN3) can provide a pathway by which nitrogen-doped carbonaceous char structures can be readily produced. Pyrolysis studies were carried out using thermogravimetric analysis and analytical Py-GC/MS of the pure compounds (DCD, 5AT, 5PT) and mixtures with cellulose, as well as proximate/ultimate analyses of the resulting chars from slow pyrolysis. Experiments showed that there is a reactive interaction between the additives and cellulose during pyrolysis, leading to greater char yields. Analysis of slow pyrolysis chars showed that DCD is promising for producing biochar with higher nitrogen content. This was attributed to the evolution of ammonia from DCD and due to its thermal decomposition occurring in a temperature range coincident with that of cellulose pyrolysis reactions.
Pyro-lytic de-oxygenation of waste cooking oil for green diesel production over Ag2O3-La2O3/AC Nano-catalyst J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-11-20 G. Abdulkareem-Alsultan, N. Asikin-Mijan, Nasar Mansir, H.V. Lee, Zulkarnain Zainal, Aminul Islam, Y.H. Taufiq-Yap
Green diesel derived from deoxygenation technology has been developed to replace instability of fatty acid alkyl ester (biodiesel) due to the presence oxygenated species. Herein, the green diesel was synthesized via catalytic deoxygenation (DO) of waste cooking oil (WCO) over synthesized Ag2O3–La2O3/ACnano catalyst under hydrogen-free environment. Based on the study, the effect of silver (Ag) species (10-30 wt%) towards DO reactivity and product distribution was investigated. It was revealed that the Ag2O(10%)–La2O3(20%)/ACnano formulation resulted in a higher yield (~89%) of liquid hydrocarbons with majority of diesel fractions selectivity (n–(C15+C17) at ~93%. In addition, decarboxylation and decarbonylation reaction processes of the WCO to DO was promoted by the presence of acid and basic active sites on Ag2O(10%)–La2O3(20%)/ACnano catalyst. The high stability of the Ag2O3 (10%)–La2O3(20%)/ACnano catalyst was proven by maintenance of six continuous runs with constant yield (>80%) of hydrocarbons and (>93%) selectivity of n–(C15+C17) under mild reaction conditions.
Evaluation of Soil Burial Biodegradation Behavior of Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) on the Basis of Change in Copolymer Composition Monitored by Thermally Assisted Hydrolysis and Methylation-Gas Chromatography J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-11-20 Siti Baidurah, Paramasivam Murugan, Khok Yong Sen, Yoko Furuyama, Mina Nonome, Kumar Sudesh, Yasuyuki Ishida
Soil burial biodegradation behavior of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) [P(3HB-co-3HHx)] was studied based on its copolymer composition determined by thermally assisted hydrolysis and methylation-gas chromatography (THM-GC). The change in copolymer composition of P(3HB-co-3HHx) film samples during soil burial degradation test was monitored in detail by THM-GC. As a result, the copolymer compositions of 3HB units gradually increased, while those of 3HHx units decreased with soil burial time, almost correlating with recovery weight. Based on these results, the biodegradation mechanism of P(3HB-co-3HHx) was elucidated with considering the influence of the crystallinity on the biodegradability. Furthermore, local differences in biodegradability of a given P(3HB-co-3HHx) film after soil burial test were also successfully evaluated from the copolymer compositions obtained by THM-GC.
Correlation between mechanical properties and thermochemical behaviours of waste papers in their early devolatilization stage J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-11-19 Adili Batuer, Dezhen Chen, Lijie Yin, Yuheng Feng
This article details a correlation study on early devolatilization behaviors (drying & volatile emission at 25–240 °C) and the change in mechanical properties (expressed by viscoelasticity) of four types of waste papers. The early stage of devolatilization was investigated using the TG-FTIR and mechanical properties using the dynamic mechanical analysis (DMA) method. The results show that the elastic and viscous mechanical properties showed obvious correlations with free and bound water evaporation and volatile emission. The storage modulus (E′) and loss modulus (E″) of the papers decreased as temperature increased and at the two important temperatures, namely 100 °C, the start of bound water evaporation, and 150 °C, the start of devolatilization in TG & DTG curves, E′ showed extrema. Especially the relative storage modulus (E′r) exhibited a sudden decrease at around 150 °C, where the activation energy of thermochemical conversion jumps from low values to high values, indicating the start of devolatilization. CO2 is the major compound of the volatiles and it is well correlated with E′r in exponential function model and can be used as an index for predicting the E′r of the waste papers in their early devolatilization stage; while during the drying stage, mass loss ratio can be used to predict E′r of the waste papers.
High-temperature pyrolysis behavior of a bituminous coal in a drop tube furnace and further characterization of the resultant char J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-11-17 Zhihua Wang, Kang Zhang, Wenxin Fang, Yong He, Emily Hsu, Qian Li, Jaffri Gul-e-Rana, Kefa Cen
In order to study the high-temperature pyrolysis behavior of bituminous coal in the drop tube furnace (DTF) and better utilization of the obtained char, a typical Shenhua bituminous coal (SH) was pyrolyzed in a DTF at the temperatures of 1000-1300 °C (100 °C increments). The obtained char was then characterized using BET and FTIR methods, while its combustion, gasification and pollutant emission characteristics were explored by a thermogravimetric analyzer and online flue gas analyzer. Results show that higher pyrolysis temperature leads to more CO and less CH4 for the increased free radical rearrangement by high heating rate and carbon reduction reactions at high temperatures. Pyrolysis generally decomposes the functional groups, increases the volume of char pores, and upgrades the rank of coal. The combustion activation energy increases from 22.99 kJ/mol to 27.42 kJ/mol and the gasification is hindered with the higher pyrolysis temperature. It is notable that the NOx and SO2 emissions of the obtained char combustion are both below 30 mg/s-MJ. High-temperature pyrolysis can enhance the evolution of NH3 and HCN as volatiles, thus decreasing the NOx formation in further char combustion stages while partly decomposing the organic and inorganic sulfur compounds to impact the SO2 emission.
Effect of hydrothermal carbonization temperature on pH, dissociation constants, and acidic functional groups on hydrochar from cellulose and wood J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-11-17 Nepu Saha, Akbar Saba, M. Toufiq Reza
The aims of this work were to quantify chemical states associated with the pH, dissociation constants, and pH at point of zero charge (pHPZC) of hydrochar and to quantify the acidic functional groups on hydrochar surface. Hydrochars from cellulose and wood treated at 180, 220, and 260 °C with 30 min residence time were produced. Boehm titration was applied to analyze acidic functional groups and dissociation constants on hydrochar surfaces. FTIR spectroscopy was used to identify the functional groups qualitatively. The results of this study indicate that hydrochar becomes more acidic due to a larger number of acidic functional groups on the hydrochar surface with the increase of hydrothermal carbonization (HTC) temperature. The total number of acidic functional groups increased from 20.5 ± 0.3 µmol/g to 1267.9 ± 22.5 µmol/g and 576.6 ± 7.8 µmol/g to 680.8 ± 18.8 µmol/g for cellulose and wood, respectively.
Investigating catalytic de-oxygenation of cellulose, xylan and lignin using HZSM-5 and Fe-HZSM-5 J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-11-16 Chetna Mohabeer, Luis Reyes, Lokmane Abdelouahed, Stéphane Marcotte, Bechara Taouk
This study presents a detailed analysis of the liquid and gaseous pyrolytic products of the three principal components of biomass (cellulose, hemicellulose and lignin) using two different catalysts (HZSM-5 and its iron-modification, Fe-HZSM-5). The experiments were conducted in a semi-batch reactor under the same operating conditions for all feed materials. The results allow the determination of the provenance of aromatic compounds, which are essential components of bio-oil to be used as a bio-fuel. Transformation schemes have been proposed for each biomass component so as to better comprehend the formation of these aromatic compounds. BET specific surface area, BJH pore size distribution and FT-IR technologies have been used to characterise the catalysts, while gas chromatography-mass spectrometry (GC-MS), flame ionisation detection (GC-FID) and thermal conductivity detection (GC-TCD) were used to examine the liquid and gaseous pyrolytic products. It was firstly found that HZSM-5 favoured the decarbonylation route (production of CO), whilst Fe-HZSM-5 favoured the decarboxylation one (production of CO2) for the same feed. Then, a competition was seen to arise from the presence of the catalysts: the chemical family present in majority in the oils was the one converted by the catalysts, rather than one single family. Finally, from the transformation schemes, it was seen that even though both catalysts boosted the aromatics production, HZSM-5 produced more aromatics than its iron-modification. It was also observed that HZSM-5 formed more phenols, and hence, more coke, than Fe-HZSM-5.
Heterogeneous kinetics of timber charring at the microscale J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-11-16 Franz Richter, Guillermo Rein
Timber is becoming a popular construction material even for high-rise buildings despite its poorly understood fire behaviour. In fire, timber—a natural polymer—degrades in the thermochemical process of charring, causing it to lose its structural strength. In spite of significant research on the physics of charring, the chemical kinetics—reactions and kinetic parameters for pyrolysis and oxidation—remain challenging to model accurately. Current kinetic models are either computationally too expensive or neglect key chemical pathways. Here we derive, at the microscale, an appropriate kinetic model for fire science. First, we built from literature studies and experiments an independent kinetic model for each of timber’s main components: cellulose, hemicellulose, and lignin. Then, we combined these three models of the components into one kinetic model (8 reactions, 8 chemical species) for timber. This approach allows us to use the chemical composition of timber to account for chemical kinetics differences among timber species. This timber model is, however, only able to reproduce the trend of the experiments. Using multi-objective inverse modelling, we extract a new set of kinetic parameters from 16 high-quality experiments from the literature. The optimised kinetic model is able to capture nearly 80 high-quality experiments within the experimental uncertainty, spanning different heating rates (1-60 K/min), oxygen concentrations (0-60 %), and isothermal temperatures (220-300 °C). Further the model outperforms current kinetic model from fire science in accuracy across a wide range of experiments without an increase in complexity. Incorporated into model of heat and mass transfer, this new kinetic model could improve the understanding of the burning of timber and lead to safer designs of timber buildings.
Effects of Temperature on Pyrolysis Characteristics of Indonesia Oil Sands J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-11-16 JIA Chuxia, XIAO Yunpeng, YU Hao, GONG Shishang, WANG Qing
In this work, pyrolysis experiments were conducted on Indonesia oil sands in a Cracking device at different pyrolysis temperatures. The effects of pyrolysis temperature on total hydrocarbon yield, liquid hydrocarbon production rate and gas production rate were investigated. Below 300 °C, the pyrolysis products were mainly gaseous. However, the proportions of liquid and gas products were identical above the temperature of 300 °C. The relationship between the volume fraction of gaseous products and temperature was analyzed using gas chromatography. The presence of functional groups of methyl, methylene, aldehyde, ketone, acid, fat, alkene and aromatic hydrocarbons in liquid pyrolysis products was investigated at different pyrolysis temperatures. The pore structure, electron microscope and fractal dimension of the chars were also analyzed. The result showed that the amount of adsorbed nitrogen reached the maximum value at 450 °C. The adsorption loop of char was close to the B-type loop, and the pore was mainly the slit hole. In addition, the pore structure was very well developed. The BET specific surface area and pore volume presented their peak values at 450 °C and the fractal dimension was obtained using FHH equation, which peaked at the temperature of 450 °C. The pore structure was loose and there was no obvious connection between the particles. Finally, the overall fractal value was slightly lower than the nitrogen adsorption fractal value.
Solid Waste to Biofuels and Heterogeneous Sorbents via Pyrolysis of Wheat Straw in the Presence of Fly Ash as an in situ Catalyst J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-11-15 Lihui Gao, Jillian L. Goldfarb
Solid waste disposal imposes worldwide environmental and economic hardships. To alleviate such issues, the present work uses coal fly ash to in situ catalyze the pyrolysis of wheat straw, an abundant agricultural biomass, and to simultaneously produce heterogeneous sorbents for water treatment. Coal fly ash mixed in varying proportions with wheat straw shows a catalytic effect by lowering the temperature at which many noncondensable gaseous species are released. As the weight fraction of fly ash in the wheat straw increased from 1 to 10 wt%, the overall conversion of biomass increased. 1-5 wt% fly ash favored conversion to the gas phase (especially CO2, CH4 and C2H4), whereas the 10 wt% mixture produced more condensable species with fewer detectable oxygenated components and increased furan concentration. For a more complete waste-to-byproduct transformation, the resulting heterogeneous wheat straw-fly ash biochars were used to removed methylene blue, a model organic pollutant, from water, at higher capacities and faster rates than biochar alone. Overall, the coal fly ash may be a potential inexpensive catalyst for in situ upgrading biomass pyrolysis, simultaneously producing heterogeneous sorbents with enhanced adsorption capacities for organic pollutants.
Is it possible to increase the oil yield of catalytic pyrolysis of biomass? A study using commercially-available acid and basic catalysts in ex-situ and in-situ modus J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-11-12 Daniele Castello, Songbo He, M. Pilar Ruiz, Roel J.M. Westerhof, Hero Jan Heeres, Kulathuiyer Seshan, Sascha R.A. Kersten
Catalytic pyrolysis of woody biomass and cellulosic materials has been investigated by analyzing the effect of catalysts on aqueous phase (sugar rich) and oil phase (lignin rich) organics produced by the preceding thermal pyrolysis. Tests were done in a downer reactor using ZSM-5 and Na2O/γ-Al2O3 as typical commercially available catalysts. Both catalysts converted the aqueous phase organics to coke, water and gas, and deoxygenated and cracked the oil phase organics. The maximum yield of oil phase organics when applying the catalysts never exceeded the corresponding oil yield of thermal pyrolysis (~22% on carbon basis). Analysis of new results of ex-situ with in-situ catalysis, in combination with earlier reported data, indicates that a path forward to obtain higher oil yields is not expected to come from process improvements. The development of catalysts that can convert the aqueous phase organics (potentially ~35% on carbon basis) into organic phase ones, instead of cracking and polymerizing them to respectively gas and char, should be considered.
The effect of alkali metal chlorides and temperature on acid-hydrolysis residual pyrolysis products J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-11-13 Qianqian Guo, Guanyi Chen, Zhanjun Cheng, Beibei Yan, Wenchao Ma, Li'an Hou
Acid-hydrolysis residual (AHR) offers significant potential for harvesting chemical energy with simultaneous reduction of environmental pollution, providing carbon neutral (or even carbon negative) sustained energy production, energy security and alleviating social concerns associated with the wastes. In this study, the different effects of intrinsic and extrinsic K and Na were compared firstly. In addition, the effect of different content of alkali metal chlorides doped into AHR and temperature on pyrolysis products were investigated, especially for the phenolic products in bio-oil, along with the grey relational analysis. The results showed that KCl and NaCl promoted the generation of char and gas at the expense of the bio-oil yield. While, addition of KCl and NaCl could increase the yields of total phenolic species. Specifically, the yields of phenols and hydroxy phenols increased, while the guaiacols and syringols content decreased. The effect of KCl on the distribution of pyrolysis products and phenolic species was somewhat greater than NaCl, especially for bio-oil yield. The increasing of pyrolysis temperature would increase gas yield and reduce the char yield. While the bio-oil yield was peaked at 650 ℃. Besides, higher temperature restrained the generation of syringols and promoted the generation of phenols and hydroxy phenols. The grey relational analysis of KCl and temperature showed that KCl content was the major factor in the generation of bio-oil in pyrolysis process, while temperature played more notable role on the yields of total phenolic species, phenols, hydroxy phenols, guaiacols and syringols. The addition of alkali metal chlorides could promote the pyrolysis process and enhance the maximum lower heating value (LHV) of pyrolysis gas, especially the addition of NaCl. The optimal value of addition amount of KCl and NaCl was found to be 2 wt.% and 0.5 wt.%, respectively. Besides, the addition of KCl and NaCl could improve pore quality and activation of AHR pyrolysis char. Based on the pyrolysis products from cellulose, it can be proposed that cellulose has two main pathway depending on the alkali metal chlorides content.
Catalytic pyrolysis of lignin over hierarchical HZSM-5 zeolites prepared by post-treatment with alkaline solutions J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-11-13 Songshan Tang, Changsen Zhang, Xiangfei Xue, Zeyou Pan, Dengtai Wang, Ruiqin Zhang
The application of hierarchical HZSM-5 zeolite catalysts in the catalytic fast pyrolysis (CFP) of lignin was investigated using a pyrolyzer coupled with gas chromatography-mass spectrometry (Py-GC-MS). A series of modified HZSM-5 zeolites were prepared by the post-treatment desilication of commercial HZSM-5 zeolite with varying concentrations of sodium hydroxide (NaOH) solutions (0.1 – 0.5 mol/L) and the following solutions: 0.3 mol/L of sodium aluminate (NaAlO2), 0.3 mol/L of sodium carbonate (Na2CO3), and 0.3 mol/L of tetrapropylammonium hydroxide (TPAOH). The catalyst samples were characterized by XRD, XRF, TEM, N2 adsorption–desorption, and NH3-TPD techniques. The crystallinity, the SiO2/Al2O3, the morphology, the pore properties, and the density of acid sites of the HZSM-5 zeolites were changed after alkali treatment. The alkali treatment improved the catalytic performance of HZSM-5 zeolite for cracking bulky oxygenates released from lignin (such as guaiacol, syringol, and their derivatives from the pyrolysis of lignin) to produce aromatic hydrocarbons. The HZSM-5 zeolite treated with 0.3 mol/L NaOH was the optimal choice for the catalytic fast pyrolysis of lignin for producing aromatic hydrocarbons.
Biomass pyrolysis in Sn-Bi molten metal for synthesis gas production J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-11-10 Aliya Arenova, Satoshi Kodama, Hidetoshi Sekiguchi
Rapid heat transfer in molten metal can enhance biomass gasification, and combining this with catalysts can lower the process temperature and eliminate tar formation. The aim of this work was to investigate the effects of Sn-Bi molten metal and its catalytic enhancement with Ni/Al2O3 with respect to synthesis gas (H2 + CO) production by biomass pyrolytic gasification. Cellulose and aspen wood pyrolysis was performed between 500 °C and 800 °C at high and low heating rates. The proposed combined medium was effective for pyrolytic gasification, lowering the pyrolysis temperature, increasing the H2 content of the product gas, and decreasing the CH4 concentration. The combined medium also reduced the char content and eliminated tar at a high heating rate, improving the carbon conversion efficiency. The proposed medium was thus effective for biomass gasification.
Study on two-step pyrolysis of walnut shell coupled with acid washing pretreatment J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-11-10 Liqiang Zhang, Lingrui Huang, Shanshan Li, Xifeng Zhu
Two-step pyrolysis(TSP) of walnut shell(WS) coupled with acid washing pretreatment was carried out to investigate the coupling effects on improving the quality of bio-oil and selectivities of value-added chemicals by Pyrolysis-gas chromatography/mass spectrometry(Py-GC/MS). The first step temperature(T1) was set from 350 °C to 550 °C, and the second step temperature was set as 650 °C. Thermogravimetric analyzer coupled with FTIR spectrophotometer(TG-FTIR) was also used to analyze the pyrolysis characteristics of the sample. The results indicated that metallic species in walnut shell was obviously reduced after acid washing (5%HCl), hence the pyrolysis process was postponed and the bio-char yield decreased. TSP coupled with acid washing could reduce the contents of acids, ketones, alcohols, aldehydes, phenols and increased the contents of N-containg compounds, sugars and furans in the first step. The hydrocarbons content decreased and the sugars content further increased in the second step. Besides, some value-added chemicals were also enriched, such as furfural(6.19%), levoglucosan(34.29%) and 2-methoxy-4-methylphenol(6.03%), etc. It could be preliminarily concluded that T1 from 400 °C to 450 °C was suitable for achieving the high quality bio-oil and high selectivities of value-added chemicals.
Catalytic fast pyrolysis of biomass over core-shell HZSM-5@silicalite-1 in a bench-scale two-stage fluidized-bed/fixed-bed reactor J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-11-11 Changsong Hu, Huiyan Zhang, Rui Xiao
In order to inhibit the coke formation on the external surface of HZSM-5 during catalytic fast pyrolysis (CFP) of biomass, core-shell structured HZSM-5@silicalite-1 zeolite catalysts were hydrothermally synthesized through the growth of silicalite-1 along the surface of a commercial HZSM-5. The catalyst characterization results indicate that silicalite-1 outer shell layer was successfully formed on the HZSM-5 core particles. Silicalite-1 coating was proved to be effective to reduce the external acidity as well as keep the internal acidity and channel patency of core HZSM-5 by catalytic probe reactions. The catalytic performances of HZSM-5@silicalite-1 samples in CFP of biomass were investigated using a bench-scale continuous feeding two-stage fluidized-bed/fixed-bed combination reactor. The results show that the productions of olefins and BTX were promoted (especially BTX), while the formations of catalyst coke and PAHs were significantly inhibited after silicalite-1 coating.
Authentication of Schisandra chinensis and Schisandra sphenantherae in Chinese patent medicines by pyrolysis-gas chromatography/mass spectrometry and fingerprint analysis J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-11-10 Yilei Huang, Zhongping Huang, Chuichi Watanabe, Lili Wang
Authentication of Schisandra chinensis fruits (S. chinensis fruits) and Schisandra sphenantherae fruits (S. sphenantherae fruits) used in Chinese patent medicines (CPMs) was investigated by pyrolysis-gas chromatography coupled with fingerprint analysis on the basis of the lignan components. 0.3 mg powder of CPM sample was pyrolyzed in a vertical microfurnace pyrolyzer at 400 °C, and the products were directly introduced into a gas chromatograph equipped with a flame ionization detector or a mass spectrometer. Then, each sample was analyzed by the relative peak area of 12 lignan components in thus obtained pyrogram. The pyrogram fingerprints of 16 CPM samples containing S. chinensis fruits or S. sphenantherae fruits showed good reproducibility with the relative standard deviations (RSDs) of the retention time less than 0.15 % (n = 5) and the RSDs of the relative percent of peak areas less than 5.29 % (n = 5). Furthermore, the discrimination of different Schisandra fruits in CPM samples was achieved by principle component analysis (PCA) and hierarchical cluster analysis (HCA) via recognizing the 18 × 12 data matrix. The results revealed the Py-GC fingerprint combined with chemometric approach is a simple, rapid and selective method for the differentiation of Schisandra fruits used in CPMs.
Influence of vinyl ether intermediate over formation of Cβ=O and Cα=Cβ monomers during pyrolysis of lignin model dimers J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-11-10 Keiko Miyamoto, Haruo Kawamoto
Radical chain reactions of a β-ether-type lignin model dimer, 1-(3,4-dimethoxyphenyl)-2-(2-methoxyphenoxy)-1-propanol, were reinvestigated at 350 °C in closed ampoule reactors under the influence of wood (Japanese cedar) pyrolysis. The formation of vinyl ether dimers and Cβ=O monomers was observed in addition to previously reported Cα=Cβ and Cα=O monomers and veratraldehyde. The vinyl ether dimer was readily hydrolyzed to the Cβ=O monomer, which suggests that the formation of the Cβ=O-type monomers, such as homovanillin from natural lignin pyrolysis, originates from the vinyl ether intermediates. Unlike the non-phenolic dimer, the corresponding phenolic dimer did not form the vinyl ether dimer and Cβ=O monomer. The results, when using Cβ-deuterium-labeled dimers, suggest that a portion of the Cα=Cβ monomer from the phenolic dimer forms via the vinyl ether intermediate, probably through conversion into quinone methide, in which the bond dissociation energy of Cβ‒O is reduced (19.1 kcal mol−1 by density functional theory calculations). This leads to the simultaneous homolytic cleavage of the Cβ‒O bond to form the Cα=Cβ monomer. Such reactions did not proceed in the pyrolysis of the non-phenolic dimer, which is not able to form the stable quinone methide intermediate. This study can provide insight into the pyrolytic conversion of lignin, particularly the formation of Cβ=O- and Cα=Cβ-types monomer.
Influence of citric acid leaching on the yield and quality of pyrolytic bio-oils from sugarcane residues J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-11-08 Lizet Rodríguez-Machín, Luis Ernesto Arteaga-Pérez, Mehmet Pala, Koen Herregods-Van De Pontseele, Raúl Alberto Pérez-Bermúdez, Jeroen Feys, Wolter Prins, Frederik Ronsse
The effects of leaching (25 °C and 1 h) sugarcane trash (SCT) and sugarcane bagasse (SCB) with citric acid (CA) on the yields and quality of fast pyrolysis bio-oils were studied. A comparison was made with commonly used leaching agents such as water or solutions of HCl and H2SO4. The quality of the obtained bio-oils was assessed using a set of analytical techniques including elemental analysis, total acid number (TAN) and water content determinations, combustion calorimetry and gas chromatography-mass spectrometry (GC/MS) analysis. Results from the fast pyrolysis of SCT or SCB pretreated with acids reveal higher yields on raw-feedstock basis (38-45 wt.%) of the organic bio-oil fraction than those from raw and water–leached feedstock, but lower yields of water (7.6-10.2 wt.%) and char (13.1-14.9 wt.%). More than 90% of non-condensable gases were CO and CO2. The most important observations related to the effect of leaching with CA on the chemical composition of the bio-oil are a significant increase of the relative abundance of sugars from 15.1% in raw SCT to 44.7% in CA-pretreated SCT, as well as a decrease in carboxylic acids, ketones, furans and phenols with respect to the raw biomasses. These results were close to those obtained from well-known leaching agents such as HCl and H2SO4. The bio-oil from the pyrolysis of CA–leached SCT and SCB have slightly higher HHVs than those obtained from reference leaching solutions (HCl and H2SO4). In addition, the TAN showed the lowest acidity among all pretreated SCB samples.
Catalytic pyrolysis of lignin with red mud derived hierarchical porous catalyst for alkyl-phenols and hydrocarbons production J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-11-06 Shaoqing Wang, Zhihe Li, Xueyuan Bai, Weiming Yi, Fu Peng
Evolution of the mass-loss rate during atmospheric and pressurized slow pyrolysis of wheat straw in a bench-scale reactor J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-11-06 Gianluca Greco, María Videgain, Christian Di Stasi, Belén González, Joan J. Manyà
In the present study, the effects of the absolute pressure (0.1 or 0.5 MPa) and the reactor atmosphere (pure N2 or a mixture of CO2/N2) on the pyrolysis behavior of wheat straw pellets (at 500 °C) were investigated. The most interesting aspect of this work was the use of a weighing platform (with a maximum capacity of 100 kg and a resolution of 0.5 g) to monitor the real-time mass-loss data for the biomass sample (with an initial mass of 400 g). It was observed that an increased pressure considerably affects the mass-loss profiles during the pyrolysis process, leading to higher devolatilization rates in a shorter period of time. Regardless of the pyrolysis atmosphere, an increase in the absolute pressure led to higher yields of gas at the expense of produced water and condensable organic compounds. This finding could be due to the fact that an increased pressure favors the exothermic secondary reactions of the intermediate volatile organic compounds in both liquid and vapor phases. The switch from pure N2 to a mixture of CO2 and N2 at 0.1 MPa also led to a remarkable increase in the yield of produced gas at the expense of the total liquid. This could be mainly due to the promotion of the thermal cracking of the volatile organic compounds at a high partial pressure of CO2, which is also consistent with the measured higher yields of CH4 and CO. The increased yield of CO can also be seen as a direct result of the enhanced reverse Boudouard reaction, which can also explain the much higher specific surface area (and ultra-micropore volume) measured for the biochar produced under the same operating conditions (0.1 MPa and a mixture CO2/N2 as pyrolysis medium).
K2CO3-promoted methane pyrolysis on nickel/coal-char hybrids J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-11-02 Jianbo Zhang, Xing Li, Wenting Xie, Qingqing Hao, Huiyong Chen, Xiaoxun Ma
Catalytic methane pyrolysis (CMP) is an environmentally benign and promising strategy for hydrogen production. However, one of the important challenges is to creatively design and prepare catalysts with high and stable catalytic activity. To integrate both advantages of traditional metal and carbon catalysts, four effective strategies were proposed to study K2CO3-promoted CMP on nickel/coal-char hybrids in this work, including: (1) Impregnation-Thermal treatment-Mechanical mixing method, (2) Precipitation-Thermal treatment method, (3) Precipitation-In situ thermal treatment (PIT) method, and (4) Precipitation-In situ thermal treatment-Hydrogen reduction method. The results suggest that the addition of K2CO3 is the key factor to promote the catalytic activity and stability of the nickel/coal-char hybrids regardless of the preparation methods, leading to high and stable methane conversion (higher than 65% at 850 °C) in the whole 300-min CMP process. Compared to the other three preparation methods, the PIT method is considered to be one simpler and more time-saving process for synthesis of robust catalysts for CMP.
Verification of simultaneous screening for major restricted additives in polymer materials using pyrolyzer/thermal desorption gas–chromatography mass spectrometry (Py/TD-GC-MS) J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-11-03 Hiroyuki Yanagisawa, Fumitaka Maruyama, Shigehiko Fujimaki
The purpose of this study is to offer a quick and efficient way to screen out harmful additives in polymer materials and help in reducing the burden of confirming compliance with chemical regulations. Previous studies have demonstrated the possibility of using pyrolyzer/thermal desorption gas chromatography–mass spectrometry (Py/TD-GC–MS) to simultaneously determine various restricted additives in polymer materials on regulatory levels. However, in reality, such a screening technique has not yet been implemented, except for certain phthalates. The screening method has to be verified with actual samples before it can be accepted as a practical approach. Since there is no certified reference material (CRM) available for simultaneous determination of multiple additives, finding appropriate test samples is particularly crucial in the verification process. As a realistic solution to combat this situation, in-house reference materials (RMs) containing plasticizers and flame retardants were prepared as alternatives to CRMs from the mixtures of a standard solution and polymer solutions. Then, the analyte concentrations of the in-house RMs were screened via Py/TD-GC–MS. The results exhibited more than 70% of the setup values with a few exceptions. With regard to reproducibility, the relative standard deviation was less than 5% in most cases.
Investigation on composition and structure of asphaltenes during low-temperature coal tar hydrotreatment under various reaction pressures J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-11-03 Ruitian Shao, Ziwei Shen, Dong Li, Zhihui Sun, Liangjun Pei, Xu Liu, Wenhong Li, Yong Dan
Hydrotreatment (HDT) of low-temperature coal tar (LCT) were carried out in a fixed-bed hydrogenation equipment under various reaction pressures. Asphaltenes were characterized by elemental analysis (EA), gel permeation chromatography (GPC), and proton nuclear magnetic resonance (1H-NMR). As the reaction pressure increased from 6 to 12 MPa, the content of toluene insoluble compounds and asphaltenes as well as the polydispersity of asphaltenes decreased gradually, indicating that the increase of pressure inhibited the condensation reaction of macromolecular radicals to produce toluene insoluble substance. What’s more, the removal rate of sulfur and nitrogen increased about 20% and 3%, respectively. This phenomenon revealed that sulfides were gradually removed as reaction pressure increased, owing to different removal degree of alkylates, thioethers, sulfoxides and sulfones in sulfides of LCT asphaltenes. By contrast, the increase of reaction pressure had negligible effect on removal rate of nitrogen because aromaticity (fA) of LCT asphaltenes is high and nitrogen mainly exist in the form of heterocyclic nitrides (more than 85 %), which are difficult to be removed. By analyzing the structure, fA of LCT asphaltenes tended to decrease and the condensation degree parameter of the aromatic ring system (HAU/CA) increased gradually, indicating that the aromatic of the asphaltenes’ unit layers lessened and the condensation degree of aromatic rings decreased. In addition, the naphthenic ring number (Rn) remains almost unchanged, while the aromatic ring number (RA) reduced with the increase of pressure, demonstrating that the ring-opening rate of naphthenic ring and the hydrogenation saturation rate of aromatic ring during the HDT process of LCT are almost equal.
Electrical properties modulation in spray pyrolysed Cu2SnS3 thin films through variation of copper precursor concentration for photovoltaic application J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-11-03 Biren Patel, Ranjan K. Pati, Indrajit Mukhopadhyay, Abhijit Ray
Thin film of Cu2SnS3 (CTS), a truly inexpensive photovoltaic absorber is deposited by low cost and non-vacuum spray pyrolysis technique on glass substrates. As deposited CTS films are of p-type in nature, however they are characterised with undesirably high free carrier concentration which leads to a large amount of recombination. Such a high carrier concentration is successfully reduced from 1020 cm-3 to the order of 1018 cm-3 by varying the initial molar copper concentration in the precursor solution. A combined XRD and Raman spectroscopy analysis reveals that the coexistence of secondary Cu3SnS4 phase is responsible for the higher carrier concentration of the order of 1021 cm-3, due to its semi-metallic nature. The optical study of the film also shows the reduction in the band gap from 1.73 eV to 1.29 eV with the absorption coefficient of >104 cm-1. These features of the precursor optimised CTS film enable it as a promising photovoltaic absorber.
Evaluation of process parameters on high-density polyethylene hydro-liquefaction products J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-11-01 Zeyou Pan, Xiangfei Xue, Changsen Zhang, Dengtai Wang, Yunyun Xie, Ruiqin Zhang
• The hydro-liquefaction of high-density polyethylene (HDPE) was studied in the absence of a solvent. The influence of reaction temperature (400–440 °C), initial H2 pressure (1–4 MPa), and reaction time (2–6 h) on the product was investigated using Ni/Al2O3 as a catalyst. Results showed that increased reaction temperature and time promoted hydrocarbon cracking, thereby favoring the enhancement of C7–C16 selectivity, whereas the high initial H2 pressure (4 MPa) preferentially facilitated the production of C17–C27 hydrocarbons and improved alkene hydrogenation. The effect of catalyst support (Al2O3, SAPO-11, and HZSM-5) was also examined. Al2O3 presented the highest liquid yield because of its weak acidity, with the liquid product dominated by n-alkanes (78.88%), whereas the yield of the liquid obtained from HZSM-5 as a catalyst support was the lowest, and aromatics was the major component (56.75%). SAPO-11 exhibited excellent selectivity for iso-alkanes, which improved the quality of the liquid oil. Meanwhile, liquid oil obtained using SAPO-11 was compliant with commercial jet-fuel standards and can be directly used as a jet-fuel additive. From this perspective, the hydro-liquefaction is a technology with potential for energy recovery from waste plastic.
Fast pyrolysis of tannins from pine bark as a renewable source of catechols J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-10-31 Oscar Pinto, Romina Romero, Marion Carrier, Jörn Appelt, Cristina Segura
New insights into the thermal behavior and decomposition of sodium propionate J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-10-31 J.-C. Grivel
Na-propionate (NaC2H5CO2) was synthesized from Na2CO3 dissolved in propionic acid. Its thermal behavior was studied in argon and in air. In both atmospheres, two solid-solid phase transitions occur below 250 °C and are followed by melting near 290 °C. Thermal decomposition begins with release of CO2 attributed to the decomposition of a limited amount of propionyl radicals. Elemental carbon results from this process. This initial reaction is followed by a faster conversion reaction into Na2CO3 with evolution of 3-pentanone, CO2, CO, CH4 and C2H4 as found during pyrolysis in argon. In air, oxidative decomposition takes place with CO2 and H2O as main released gases. The stability of Na-propionate is reduced in air compared to argon atmosphere. The reaction paths are discussed and compared with previously published results on Na-propionate and other propionate metalorganic compounds. The potential of using the low temperature phase transitions of Na-propionate for thermal energy storage (ΔH ≈ 245 J/g) was evaluated by submitting samples to 25 heating/cooling cycles.
Identifying the Structures Retained when Transforming Wood into Biocarbon J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-10-29 Johnathon N. Caguiat, Daniel S. Yanchus, Randeep S. Gabhi, Donald W. Kirk, Charles Q. Jia
Biocarbon is a carbon-rich, porous material derived from biomass, and a promising electrode material for supercapacitors. Supercapacitors are fast-charging, long-lasting energy storage devices that have high power density and low energy density, relative to batteries. Many of the most recent efforts to raise the energy density of supercapacitors focus on increasing the gravimetric capacitance (F/g) of the electrode material. However, the electrodes in commercial supercapacitors are thin films (<50 μm), limiting the volume fraction of the electrode material within a device and, ultimately, its energy density. The use of thick monolithic electrodes (>1 mm thick) may alleviate this limitation, but only if monoliths can be made electrically conductive and facilitate ion migration in electrolyte. Whilst electrode thickness inevitably raises the overall resistance, the extent to which resistance is raised depends on the structure of the pores. This is also the case with electrolyte transport, making the pore structure of a monolith a key factor in improving performance. We use electron deceleration with a scanning electron microscope, physisorption, and x-ray diffraction to better understand what wood structures may be retained in biocarbon, and what new structures may be created when transforming wood to biocarbon. The features in four biocarbon samples are studied: one commercial hard-wood biocarbon, and three in-house biocarbon made from poplar, black locust, and pine via a slow pyrolysis procedure. The macro features of wood (those > 1 μm, such as vessels, rays tracheids and pits) are retained in all four biocarbon samples. However, the retention of submicron wood features (e.g. layered structures within cell wall) is determined by pyrolysis conditions. Fast heating retained some submicron morphological structures in the commercial biocarbon, while the slow pyrolysis biocarbons did not have any distinguishable submicron features. The physisorption data suggested that the distributions of mesopores (2 to 50 nm) varied between biocarbons. X-ray diffraction showed the graphite nano-crystallites in all four biocarbon samples, but with significant size variations. Further study is necessary to learn how to tune the distribution of pore sizes, in order to create biocarbons with desirable pore structures.
Pyrolysis of sawdust with various Fe-based catalysts: Influence of support identity on hydrogen production J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-10-26 Shuangxia Yang, Xiaodong Zhang, Lei Chen, Laizhi Sun, Baofeng Zhao, Hongyu Si, Xinping Xie, Fanjun Meng
Hydrogen production from catalyst pyrolysis of sawdust was studied using various supported Fe-based catalysts derived from layered double hydroxides (LDHs) precursor in a two-stage fixed bed reactor. Specifically, the effect of support identity (Fe–Mg, Fe–Ca and Fe–Al) on the physicochemical properties and catalytic performances in relation to hydrogen production and coke formation on reacted catalyst were investigated. Various characterization techniques such as XRD, SEM, BET, H2-TPR and TG-DTG temperature-programmed oxidation (TPO) were employed to thoroughly characterize the fresh and reacted Fe-based catalysts. It is revealed that the support identity plays an important role in determining the iron species form, textural properties and catalytic abilities of the resulting catalyst. The Al supported Fe-based catalyst is found to be the most effective for hydrogen production with the highest gasification efficiency of 61.4 wt.%, syngas yield of 598 mL/g biomass, H2 yield of 217 mL/g biomass, and H2/CO molar ratio of 2.4. Based on the results of structure characteristics, this might be due to its fine particle, enhanced reducibility, high surface area and generation of surface acidity by introduction of Al form, which can provide efficient active sites for pyrolysis vapors to crack and reform through a series of catalytic reaction. TPO analysis shows that the reacted Fe–Ca catalyst has the highest amount of coke formation with most of the deposited carbon detected to be high value filamentous carbon. According to GC-MS experiment results, the Fe–Al catalyst is capable for selective aromatics compounds production from biomass pyrolysis, with the maximum yield as high as 100%. Therefore, using the Fe–Al catalyst developed in this work could provide a promising route for hydrogen-rich syngas production from catalytic pyrolysis of biomass.
Characterization of defatted cottonseed meal-derived pyrolysis bio-oil by ultrahigh resolution electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-10-26 Zhongqi He, Mingxin Guo, Rachel L. Sleighter, Hailin Zhang, Fortier Chanel, Patrick G. Hatcher
Defatted cottonseed meal is a N-rich biomass that deserves valorized recycling. In this work, slow pyrolysis was applied to produce pyrolytic bio-oil from this biomass. Both the upper oily and lower aqueous fractions were characterized by elemental analysis, Fourier transform infrared (FT-IR) spectroscopy, and ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) with both negative and positive electrospray ionization modes. The contents of C and S were much higher in the oily fraction than in the aqueous fraction. Furthermore, the composition and molecular formulas of the organic compounds in the oily fraction were much more complex and diverse. From the mass spectral analysis, 9 and 14 different oxygen heteroatom classes were detected in the aqueous and oily fractions, respectively. While CHON compounds were found in both fractions, CHONS compounds were detected only in the oily fraction. The van Krevelen diagrams from the FT-ICR-MS data showed the presence of lipid-, peptide-, and lignin-like components in both fractions. However, carbohydrate-like components were found only in the oily fraction. Furthermore, the diagrams revealed more N species in the oily fraction that mostly clustered with O/C < 0.2 in the unsaturated hydrocarbon-like region. On the other hand, there were less N species in the aqueous fraction, and they were present mostly in the lipid-like region. This information is useful for both chemical fingerprinting of cottonseed meal/cake-based bio-oils and guiding the effective uses of these N-rich types of products as a bioenergy resource and as an industrial feedstock.
Novel Instrumentation for Tracking Molecular Products in Fast Pyrolysis of Carbohydrates with Sub-Second Temporal Resolution J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-10-24 Carolyn P. Hutchinson, D. Paul Cole, Erica A. Dalluge, Evan A. Larson, Young Jin Lee
CHARACTERIZATION OF ANALYTICAL FAST PYROLYSIS VAPORS OF MEDIUM-DENSITY FIBERBOARD (MDF) USING METAL-MODIFIED HZSM-5 J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-10-24 Francieli M. Mayer, Camila M. Teixeira, José G.A. Pacheco, Claudia T. de Souza, Deiverti V. Bauer, Elina B. Caramão, Juliana S. Espindola, Jorge O. Trierweiler, Oscar W. Perez-Lopez, Claudia A. Zini
The high total worldwide production of MDF residues represents a concern due to its low value applications, disposal, and toxic potential. Catalytic and thermal fast pyrolyses of MDF wastes were studied using analytical pyrolysis-GC/MS. HZSM-5S impregnated with 5 metals were synthesized, characterized and designated as Co5S, Fe5S, Nb5S, Ni5S and Zn5S. All catalysts improved the percentage of monoaromatic hydrocarbons (MAH, 23.77 to 47.61%) and of PAH (0.66 to 5.07%), while they were not detected in thermal pyrolyses of the 4 MDF residues. Among catalysts, Ni5S improved the selectivity of BTX compared to HZSM-5S (26.22 to 37.90%), followed by Fe5S (31.40%). Performance of Co5S and Nb5S was similar to HZSM-5S, while Zn5S provided a lower MAH content (23.77%). The increase in hydrocarbons turned bio-oil into a product that more closely resembles fuel composition, while thermal pyrolyses provided mainly oxygenated compounds, that can be used in other uses.
Soil carbon stabilization pathways as reflected by the pyrolytic signature of humic acid in agricultural volcanic soils J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-10-22 Z. Hernández, G. Almendros, A. Álvarez, T. Figueiredo, P. Carral
Molecular assessment of the origin and transformation processes of soil organic matter (SOM) was carried out based on information obtained from 13C NMR and analytical pyrolysis of humic acids (HAs) in soils from wine-growing regions in Tenerife (Canary Islands, Spain). Principal component analysis, using as variables pyrolysis products, shows different soil groups defined by the molecular assemblages released from the corresponding HAs, characterized by the predominance of: i) plant biomacromolecules (lignin) in soils on pumice substrate, ii) heterocyclic N-compounds and methoxyl-lacking aromatic structures, iii) a substantial domain of alkyl compounds in cultivated soils with active C turnover and finally, iv) polysaccharide and protein-derived compounds in soils developed on amorphous gels. The proportions of the pyrolytic compounds from soil HAs were represented by an upgraded graphical-statistical method (3D Van Krevelen plot) that was used to compare the major SOM structural domains in the different soils. The above results coincide with those suggested by the 13C NMR analysis, and were associated to two groups of local land management practices, in terms of their intensity respectively favoring either the transformation of plant-inherited macromolecular precursors from vascular plants, or the humification of aliphatic precursors in the presence of specific mineralogical substrates controlling microbial degradation and humification processes.
Thermal degradation of medical plastic waste by in-situ FTIR, TG-MS and TG-GC/MS coupled analyses J. Anal. Appl. Pyrol. (IF 3.468) Pub Date : 2018-10-19 Linbo Qin, Jun Han, Bo Zhao, Yu Wang, Wangsheng Chen, Futang Xing
In this paper, thermal degradation of medical plastic waste (the blends of medicinal plastic bottles and plastic infusion bag) that mainly composed of polystyrene (PS) and polypropylene (PP) is studied under both inert and oxidative atmospheres using in-situ FTIR, TG-MS and TG-GC/MS coupled analyses. Meanwhile, the gas evolution profiles as well as the function groups of the decomposition residues during medical plastic waste thermal degradation are also discussed. The aliphatic C-H, aromatic C=C and aromatic C-H exhibit the dramatically vary with temperature, indicating the medical plastic waste begins vitrifying at about 100 °C, starts degrading around 300 °C and reaches to the maximum near 400 °C in inert atmosphere, produces mainly styrene, benzene, toluene, and small amounts of C1-C4 aliphatic hydrocarbons as the initial pyrolysis products. The aromatic compounds are mainly ascribed to PS degradation, and alkanes and alkenes are mainly originated from PP creaking. It is also found that the gaseous evolution profiles are well consistent with DTG curves in terms of appearance of peaks and relevant stages in the whole temperature range. Compared with thermal degradation of medical plastic waste in inert atmosphere, the initial degradation temperature for the medical plastic waste is shifted to lower temperature, while the degradation rate is reduced significantly in the oxidative atmosphere that produces oxygenated hydrocarbons such as acetic acid, phenol and benzoic acid due to the O-atom attack. Lastly, the initial creaking mechanism together with the secondary reaction pathways of the primary volatiles produced from medical plastic waste thermal degradation are also proposed.
Some contents have been Reproduced by permission of The Royal Society of Chemistry.
- Acc. Chem. Res.
- ACS Appl. Mater. Interfaces
- ACS Biomater. Sci. Eng.
- ACS Catal.
- ACS Cent. Sci.
- ACS Chem. Biol.
- ACS Chem. Neurosci.
- ACS Comb. Sci.
- ACS Earth Space Chem.
- ACS Energy Lett.
- ACS Infect. Dis.
- ACS Macro Lett.
- ACS Med. Chem. Lett.
- ACS Nano
- ACS Omega
- ACS Photonics
- ACS Sens.
- ACS Sustainable Chem. Eng.
- ACS Synth. Biol.
- Acta Biomater.
- Acta Crystallogr. A Found. Adv.
- Acta Mater.
- Adv. Colloid Interface Sci.
- Adv. Electron. Mater.
- Adv. Energy Mater.
- Adv. Funct. Mater.
- Adv. Healthcare Mater.
- Adv. Mater.
- Adv. Mater. Interfaces
- Adv. Opt. Mater.
- Adv. Sci.
- Adv. Synth. Catal.
- AlChE J.
- Anal. Bioanal. Chem.
- Anal. Chem.
- Anal. Chim. Acta
- Anal. Methods
- Angew. Chem. Int. Ed.
- Annu. Rev. Anal. Chem.
- Annu. Rev. Biochem.
- Annu. Rev. Environ. Resour.
- Annu. Rev. Food Sci. Technol.
- Annu. Rev. Mater. Res.
- Annu. Rev. Phys. Chem.
- Appl. Catal. A Gen.
- Appl. Catal. B Environ.
- Appl. Clay. Sci.
- Appl. Energy
- Aquat. Toxicol.
- Arab. J. Chem.
- Asian J. Org. Chem.
- Atmos. Environ.
- Carbohydr. Polym.
- Catal. Commun.
- Catal. Rev. Sci. Eng.
- Catal. Sci. Technol.
- Catal. Today
- Cell Chem. Bio.
- Cem. Concr. Res.
- Ceram. Int.
- Chem. Asian J.
- Chem. Bio. Drug Des.
- Chem. Biol. Interact.
- Chem. Commun.
- Chem. Educ. Res. Pract.
- Chem. Eng. J.
- Chem. Eng. Sci.
- Chem. Eur. J.
- Chem. Mater.
- Chem. Phys.
- Chem. Phys. Lett.
- Chem. Phys. Lipids
- Chem. Rev.
- Chem. Sci.
- Chem. Soc. Rev.
- Chin. J. Chem.
- Colloids Surf. B Biointerfaces
- Combust. Flame
- Compos. Part A Appl. Sci. Manuf.
- Compos. Sci. Technol.
- Compr. Rev. Food Sci. Food Saf.
- Comput. Chem. Eng.
- Constr. Build. Mater.
- Coordin. Chem. Rev.
- Corros. Sci.
- Crit. Rev. Food Sci. Nutr.
- Crit. Rev. Solid State Mater. Sci.
- Cryst. Growth Des.
- Curr. Opin. Chem. Eng.
- Curr. Opin. Colloid Interface Sci.
- Curr. Opin. Environ. Sustain
- Curr. Opin. Solid State Mater. Sci.
- Ecotox. Environ. Safe.
- Electrochem. Commun.
- Electrochim. Acta
- Energy Environ. Sci.
- Energy Fuels
- Energy Storage Mater.
- Environ. Impact Assess. Rev.
- Environ. Int.
- Environ. Model. Softw.
- Environ. Pollut.
- Environ. Res.
- Environ. Sci. Policy
- Environ. Sci. Technol.
- Environ. Sci. Technol. Lett.
- Environ. Sci.: Nano
- Environ. Sci.: Processes Impacts
- Environ. Sci.: Water Res. Technol.
- Eur. J. Inorg. Chem.
- Eur. J. Med. Chem.
- Eur. J. Org. Chem.
- Eur. Polym. J.
- J. Acad. Nutr. Diet.
- J. Agric. Food Chem.
- J. Alloys Compd.
- J. Am. Ceram. Soc.
- J. Am. Chem. Soc.
- J. Am. Soc. Mass Spectrom.
- J. Anal. Appl. Pyrol.
- J. Anal. At. Spectrom.
- J. Antibiot.
- J. Catal.
- J. Chem. Educ.
- J. Chem. Eng. Data
- J. Chem. Inf. Model.
- J. Chem. Phys.
- J. Chem. Theory Comput.
- J. Chromatogr. A
- J. Chromatogr. B
- J. Clean. Prod.
- J. CO2 UTIL.
- J. Colloid Interface Sci.
- J. Comput. Chem.
- J. Cryst. Growth
- J. Dairy Sci.
- J. Electroanal. Chem.
- J. Electrochem. Soc.
- J. Environ. Manage.
- J. Eur. Ceram. Soc.
- J. Fluorine Chem.
- J. Food Drug Anal.
- J. Food Eng.
- J. Food Sci.
- J. Funct. Foods
- J. Hazard. Mater.
- J. Heterocycl. Chem.
- J. Hydrol.
- J. Ind. Eng. Chem.
- J. Inorg. Biochem.
- J. Magn. Magn. Mater.
- J. Mater. Chem. A
- J. Mater. Chem. B
- J. Mater. Chem. C
- J. Mater. Process. Tech.
- J. Mech. Behav. Biomed. Mater.
- J. Med. Chem.
- J. Membr. Sci.
- J. Mol. Catal. A Chem.
- J. Mol. Liq.
- J. Nat. Gas Sci. Eng.
- J. Nat. Prod.
- J. Nucl. Mater.
- J. Org. Chem.
- J. Organomet. Chem.
- J. Photochem. Photobiol. C Photochem. Rev.
- J. Phys. Chem. A
- J. Phys. Chem. B
- J. Phys. Chem. C
- J. Phys. Chem. Lett.
- J. Polym. Sci. A Polym. Chem.
- J. Porphyr. Phthalocyanines
- J. Power Sources
- J. Solid State Chem.
- J. Taiwan Inst. Chem. E.
- Macromol. Rapid Commun.
- Mass Spectrom. Rev.
- Mater. Chem. Front.
- Mater. Des.
- Mater. Horiz.
- Mater. Lett.
- Mater. Sci. Eng. A
- Mater. Sci. Eng. R Rep.
- Mater. Today
- Meat Sci.
- Med. Chem. Commun.
- Microchem. J.
- Microchim. Acta
- Micropor. Mesopor. Mater.
- Mol. Biosyst.
- Mol. Cancer Ther.
- Mol. Catal.
- Mol. Nutr. Food Res.
- Mol. Pharmaceutics
- Mol. Syst. Des. Eng.
- Nano Energy
- Nano Lett.
- Nano Res.
- Nano Today
- Nano-Micro Lett.
- Nanomed. Nanotech. Biol. Med.
- Nanoscale Horiz.
- Nat. Catal.
- Nat. Chem.
- Nat. Chem. Biol.
- Nat. Commun.
- Nat. Energy
- Nat. Mater.
- Nat. Med.
- Nat. Methods
- Nat. Nanotech.
- Nat. Photon.
- Nat. Prod. Rep.
- Nat. Protoc.
- Nat. Rev. Chem.
- Nat. Rev. Drug. Disc.
- Nat. Rev. Mater.
- Natl. Sci. Rev.
- Neurochem. Int.
- New J. Chem.
- NPG Asia Mater.
- npj 2D Mater. Appl.
- npj Comput. Mater.
- npj Flex. Electron.
- npj Mater. Degrad.
- npj Sci. Food
- Pharmacol. Rev.
- Pharmacol. Therapeut.
- Photochem. Photobiol. Sci.
- Phys. Chem. Chem. Phys.
- Phys. Life Rev.
- PLOS ONE
- Polym. Chem.
- Polym. Degrad. Stabil.
- Polym. J.
- Polym. Rev.
- Powder Technol.
- Proc. Combust. Inst.
- Prog. Cryst. Growth Ch. Mater.
- Prog. Energy Combust. Sci.
- Prog. Mater. Sci.
- Prog. Photovoltaics
- Prog. Polym. Sci.
- Prog. Solid State Chem.