Exploratory Analysis of Campos Basin Crude Oils via Geochemical Parameters by Comprehensive Two-Dimensional Gas Chromatography/Time-of-Flight Mass Spectrometry Energy Fuels (IF 3.024) Pub Date : 2018-09-25 Lívia C. Santos, Georgiana F. da Cruz, Bárbara M. F. Ávila, Vinícius B. Pereira, Débora A. Azevedo
Comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC×GC–TOFMS) was used for geochemical characterization of 18 oil samples from Campos Basin, Brazil. Conventional analyses were also performed on these oils (API gravity and GC-FID) and in the maltenic fraction (saturated, aromatic, and polar analysis) after asphaltene precipitation, aiming the oil screening for a rapid assessment of general characteristics. The results from principal component analysis with the biomarker parameters of source, maturity, and biodegradation obtained by GC×GC–TOFMS separated the oils into two groups, mainly explained by gammacerane content. The higher sensitivity and resolution of GC×GC–TOFMS allowed the identification of unusual compounds in oils from this basin, such as methylhopanes (whose calculated ratios allowed the oils in this work to be classified as having a marine, lacustrine, or “mixed” source, the same interpretation obtained by statistical analysis), moretanes (with results that reinforce the hypothesis of same thermal evolution for the studied samples), and short-chain steranes (C21 and C22), detected in very low concentrations in all of the samples. This study is the first to show the presence of these compounds in Campos Basin crude oils.
Effect of Ion Type on the Interaction between Polar Model Oil and Mica Substrate: A Chemical Force Microscopy Study Energy Fuels (IF 3.024) Pub Date : 2018-09-25 Jian Zhang, Fanghui Liu, Hui Yang, Yuejun Zhu, Xiujun Wang, Zhao Hua
Oxy-Fuel Combustion Characteristics of Pulverized Coal in a 3 MW Pilot-Scale Furnace Energy Fuels (IF 3.024) Pub Date : 2018-09-25 Junjun Guo, Tai Zhang, Xiaohong Huang, Wei Luo, Fan Hu, Zixue Luo, Pengfei Li, Zhaohui Liu
This paper reports the oxy-fuel combustion characteristics in a pilot-scale furnace with a bituminous coal. After discussing the design principles of oxy-fuel burners in detail, a swirling low-NOx burner system is specially designed to achieve the compatible combustion of air-fuel combustion and oxy-fuel combustion. The initial O2 concentrations vary between 22 and 30% by volume in the oxy-fuel combustion. A reliable transition process is performed between different combustion modes. Measurements of flame images, burnout rate, heat transfer, and pollution emission are carried out. The results show that compatible and stable combustion with low NOx emissions is achieved in different combustion modes. A high time-averaged CO2 concentration of 81.5% by volume is achieved in the dry flue gas. In this test facility, compared to air-fuel combustion, the averaged burnout rate of pulverized coal slightly increases (∼97%) despite the decrease in flame temperature. There is an optimal initial O2 concentration between 26 and 30% by volume, which can achieve a similar heat transfer process with air-fuel combustion. By using a low-NOx oxy-fuel burner system and flue gas recycle, NOx emissions decrease to a level that is 30–50% of that in air-fuel combustion. The oxy-fuel combustion with a low-NOx oxy-fuel burner system is confirmed for efficiently and cleanly burning pulverized coal.
Identification of Artifacts in the Methylation Process of Sulfur Compounds in Petroleum Energy Fuels (IF 3.024) Pub Date : 2018-09-25 Ping Wang, Chunming Xu, Yahe Zhang, Meng Wang, Quan Shi
Methylation of sulfides and thiophenes into methyl sulfonium salts for electrospray ionization (ESI) mass spectrometry analysis has been a widely used approach for molecular characterization of sulfur-containing compounds in fossil fuels. In this study, we found a series of artifacts in the methylation products of crude oils, which could lead to incorrect assignment of sulfur compounds, severe ionization suppression of S1 species with a high double bond equivalent value, and OxSx species with low abundance. The terminal products from the Friedel–Craft methylation of toluene and its methyl homologues were identified as 1,1,2,3,4,5,6-heptamethylbenzenonium, which showed high abundance in the positive-ion ESI mass spectrum. These compounds associate with Ag+, leading to the formation of abundant Ag-cationized monomer and homo- and hetero-Ag-cationized dimer complexes. In-source high-energy collisional dissociation (HCD) of the homo- and hetero-Ag-cationized dimer complexes [M1 + Ag + M1]+ and [M1 + Ag + M2]+ yielded the monomer complexes [M1 + Ag]+, which further fragmented to yield the molecular ion [M1]+. The abundant Ag-cationized complexes seriously interfered with the identification of sulfur compounds. Feasible suggestions are made to eliminate the interference by Ag-cationized complexes.
Removal and Emission Characteristics of Condensable Particulate Matter in an Ultralow Emission Power Plant Energy Fuels (IF 3.024) Pub Date : 2018-09-25 Chenghang Zheng, Yipan Hong, Shaojun Liu, Zhengda Yang, Qianyun Chang, Yongxin Zhang, Xiang Gao
Particulate matter (PM) emitted from stationary sources can be classified into filter particulate matter (FPM) and condensable particulate matter (CPM). Because CPM significantly contributes to total emission, a method and an instrument for testing and measuring CPM were developed on the basis of the principle of dilution and condensation. Then, a parallel sampling analysis of CPM and FPM was carried out at the inlet of a desulfurization system and stack of coal-fired units. Results showed that CPM accounted for 76.73% of the total particulate concentration and the removal efficiencies of FPM and CPM were 94.93 and 65.37%, respectively, after wet flue gas desulfurization (WFGD) and wet electrostatic precipitator (WESP). The microscopic morphology, ion concentration, and organic components of CPM were analyzed. CPM was dispersed after formation, and most of them were smaller than 2.5 μm. The main element components were Al, Ca, Na, Fe, Si, C, O, S, F, and Cl. Na+ was the most abundant metal cation in the CPM sample. The main parts of the inorganic anions were F– and Cl–. C10–C19 and C20–C29 were the main components of the alkanes, while the alkanes above C30 were only 3.93 and 6.29% at the WFGD inlet and WESP outlet, respectively.
Importance of Biomass and Binder Selection for Coking Briquette Preparation. Their Effect on Coal Thermoplastic Properties Energy Fuels (IF 3.024) Pub Date : 2018-09-25 L. Florentino-Madiedo, E. Díaz-Faes, C. Barriocanal, M. Castro-Díaz, C. E. Snape
Blends consisting of a high volatile bituminous coal, biomass, and binder that were used in the preparation of briquettes were analyzed in order to select the best components from the viewpoint of their influence on the coal’s thermoplastic properties. The raw materials were studied by means of thermogravimetry, high-temperature rheometry, high-temperature proton nuclear magnetic resonance (1H NMR), and Fourier transform infrared (FTIR) spectroscopy. In addition, the fluidity of the blends was determined with the standard Gieseler plastometer test method (ASTM D 2639-74). Various parameters derived from these different techniques were used to explain the effects of biomass and binder on the fluidity of the blends with coal. It was found that the deleterious effect of biomass was mainly related to its physical properties, whereas the effect of the binder was controlled by its chemical composition. Coal tar, coal tar sludge, pine sawdust, and a biocoal derived from hydrothermally treated waste biomass obtained from pruning were the best materials for the preparation of briquettes for cokemaking.
From Coreflooding and Scaled Physical Model Experiments to Field-Scale EOR Evaluations: Comprehensive Review of the Gas-Assisted Gravity Drainage (GAGD) Process Energy Fuels (IF 3.024) Pub Date : 2018-09-25 Dr. Watheq J. J. Al-Mudhafar
The Gas-Assisted Gravity Drainage (GAGD) process has been suggested to improve oil recovery in both secondary and tertiary stages through immiscible and miscible injection modes. In contrast to Continuous Gas Injection (CGI) and Water-Alternative Gas (WAG), the GAGD process takes advantage of the natural segregation of reservoir fluids to provide gravity-stable oil displacement, and improve oil recovery. In the GAGD process, the gas is injected through vertical wells at the top of reservoir to formulate a gas cap that allows oil and water to drain downwards to the reservoir bottom where horizontal producer(s) are placed. Extensive experimental works and limited reservoir-scale evaluation studies have been conducted to test the effectiveness of the GAGD process performance. In this paper, a comprehensive literature review is presented to summarize all the references about concepts, principles, and field-scale evaluations of the GAGD process. Particularly, this paper presents an introduction to the mechanisms of CO2-rock-fluid interactions, gas-EOR injection approaches, the GAGD process physical model, the factors influencing the GAGD process, and a review of all the previous field-scale evaluation studies. Furthermore, the validation of the GAGD process in reservoir-scale applications is fully discussed by focusing on its weaknesses with respect to the optimal implementation design for achieving maximum oil recovery.
Polymers of N-(pyrrolidin-1-yl)methacrylamide as High Cloud Point Kinetic Hydrate Inhibitors Energy Fuels (IF 3.024) Pub Date : 2018-09-25 Lilian S. Ree, Malcolm A. Kelland
Formation of gas hydrates is a major problem in flowlines where gas and water are transported together, and can lead to blockages, downtime, economic losses, and potential accidents. One way of preventing gas hydrates from forming, is by injection of kinetic hydrate inhibitors (KHIs). KHIs are typically water-soluble polymers, often containing amide pendant groups. Based on our previous work on high cloud point polymers of N,N-dimethylhydrazidoacrylamide (polyDMHAM) and N,N-dimethylhydrazidomethacrylamide (polyDMHMAM), we have now synthesized a series of N-(pyrrolidin-1-yl)methacrylamide polymers (polyNPyMA) which contains a pyrrolidine-substituted hydrazido pendant group. These polymers show improvement on all previous hydrazido polymers as they exhibit improved KHI performance whilst having no cloud point in deionized water or 7 wt.% aqueous NaCl up to 95 °C. Their performance as KHIs have been investigated using a high-pressure gas hydrate rocker rig at a pressure of 76 bar using a structure II-forming natural gas mixture and slow temperature ramping experiments. The best performing polymer, polyNPyMA-II, was kept in the reaction mixture of aqueous isopropyl alcohol and gave an average onset temperature of To = 8.1 °C at 2500 ppm. We have shown that isopropyl alcohol functions as a synergist with polyNPyMA, reducing the To of polyNPyMA-IV from 10.0 °C to 9.0 °C when added at 7875 ppm. A common synergist for different KHIs, n-butyl glycol ether (BGE), was found not to significantly improve the performance of polyNPyMA. An interesting feature of hydrazidoacrylamide polymers such as polyNPyMA is that they can be protonated and therefore their solubility characteristics can change with pH. PolyNPyMA was shown to perform better at neutral and high pH, and less well at low pH. The effect of pH was observed to be smaller than previously reported for polyDMHAM and polyDMHMAM suggesting that the hydrophilicity obtained by protonation of the hydrazido group affects the polymer less when the hydrazido moiety contains bigger hydrophobic groups. Finally, given the fact that KHI polymer performance is dependent on the molecular weight distribution this paper also highlights that Mn and Mw values determined by size exclusion chromatography (SEC) using calibration standards can give very different results compared to absolute methods such as multi-angle light scattering (MALS).
Experimental study of methane and methyl propanoate high-temperature kinetics Energy Fuels (IF 3.024) Pub Date : 2018-09-24 Shirin Jouzdani, Xuan Zheng, Deshawn M. Coombs, Benjamin Akih-Kumgeh
The biodiesel surrogate, methyl propanoate (MP), is more reactive than methane. Mixtures of the two can be used to control combustion initiation in various combustion systems. Reported here is a shock tube study of the influence of chemical interactions resulting from mixing the two fuels on observable combustion properties, such as global chemical time scales and species time histories. Experiments are carried out at pressures of about 4, 7.4, and 10 atm covering a temperature window of 1000 K to 1500 K. Using direct laser absorption, CO time histories during MP pyrolysis are obtained. The CO absorbance is further used to determine pyrolysis times by means of which the effect of temperature on MP pyrolysis is probed. Reactivity differences are first examined with the fuel concentration maintained at 3% and then with the oxygen concentration fixed at 10%. The evidence of chemical interactions during ignition is observed through a reduction of methane ignition delay times caused by MP addition. The influence is nonlinear, with the result that ignition delay times of blends of 50% of each fuel are much closer to the ignition delay times of MP, the more reactive fuel. This is understood to result from the rapid generation of radicals during MP oxidation which further react with methane in low-activation energy elementary reactions, such as OH which reacts almost barrier-less. With respect to CO formation during MP pyrolysis, the presence of methane is not observed to significantly influence the pyrolysis time, indicating limited radical withdrawal by methane during the propanoate pyrolysis as it is the case during oxidation when the chemical interactions are accentuated by exchange of oxygen-mediated radical formation. The measured data are compared with two model predictions, showing reasonable agreement for the ignition data and discrepancies with respect to the pyrolysis data.
Controllable synthesis of highly graphitizable pitches from 1-methylnaphthalene via closed-system dehydrobromination Energy Fuels (IF 3.024) Pub Date : 2018-09-24 Haixiao Yang, Hexiang Han, Jitong Wang, Wenming Qiao, Licheng Ling
In this paper, novel graphitizable pitches with controllable softening points and methylene-bridged structures were successfully prepared through photobromination of 1-methylnaphthalene (1-MNa) followed by closed-system dehydrobromination (CSD). The structures of bromination products and dehydrobromination pitches were determined using GC-MS, NMR and LDI-TOF/MS. It was found that the amount of bromine introduced greatly affected the composition of bromination products. 1-MNa brominated at a bromine/1-MNa molar ratio of 0.75 (BMNa-0.75) demonstrated the highest methyl bromination selectivity (Smb), which was selected as the dehydrobromination precursor. After a CSD/polymerization reaction under 200-250 oC, dehydrobromination pitches with softening points of 148-226 oC were acquired. Compared with open-system dehydrobromination (OSD), CSD endowed bromine radical longer life and boosted intramolecular and intermolecular linking, thereby substantially increasing softening points and coking values. The polymerization degree of CSD-derived pitches is highly regulable depending on dehydrobromination temperature and the amount of tetrahydronaphthalene (tetralin) introduced. Moreover, methyl migration products (naphthalene, 2-methylnaphthalene, dimethyl-naphthalene and trimethyl-naphthalene) together with hydrogenation products (mainly tetralin) were detected by analyzing the hexane-soluble components (HS). The structural features of CSD-derived pitches contributed to some unique properties such as high polymerization degree accompanied by low aromaticity, continuous molecular weight distribution and complex connection types among subunits including α-α’, α-β’ and β-β’. The semi-coke with 94% anisotropy of coarse flow texture was synthesized at 420 oC under atmospheric pressure. Well-developed graphitic carbons with graphitization degree of 81.40% and ID/IG of 0.12 was obtained from graphitization of dehydrobromination pitches under 2600 oC.
Thermothickening and Salinity Tolerant Hydrophobically Modified Polyacrylamides for Polymer Flooding Energy Fuels (IF 3.024) Pub Date : 2018-09-24 Alette Løbø Viken, Tormod Skauge, Per Erik Svendsen, Peter Aarrestad Time, Kristine Spildo
Partially hydrolyzed polyacrylamide (HPAM) is by far the most used synthetic polymer in enhanced oil recovery (EOR) projects. Shortcomings of HPAM include a highly molecular weight (Mw) dependent viscosity yield and decreasing viscosifying ability with increasing salinity and temperature. For an economically viable project, this limits its use to reservoirs with low to moderate salinities and temperatures. In that respect, hydrophobically modified polyacrylamides (HMPAM) has been suggested as an alternative for applications at higher salinities and temperatures. While studies have compared the performance of modified versus unmodified commercial EOR polymers at different salinities and temperatures, and the structure–property relationship of monodisperse, low Mw HMPAM, published data on the simultaneous effect of polymer hydrophobicity, salinity, and temperature for commercial EOR polymers are limited. This study thus presents a comprehensive series of experiments to investigate the effect of polymer hydrophobicity on viscosifying ability as a function of salinity and temperature. The main findings of these experiments are that the balance between salinity effects and thermal behavior shifts the order of viscosifying ability so that the polymer with the best viscosifying abilities at low temperatures and salinities is outperformed at conditions of high salinity and temperature. This highlights the importance of structure–activity studies at relevant reservoir conditions prior to selection of a solution for field application.
Evaluation of Spatial Alignment of Kerogen in Shale Using High-Resolution Transmission Electron Microscopy, Raman Spectroscopy, and Fourier Transform Infrared Energy Fuels (IF 3.024) Pub Date : 2018-09-24 Yu Liu, Yanming Zhu, Shangbin Chen, Yang Wang, Yu Song
As the three-dimensional (3D) molecular structure of kerogen plays important roles in further understanding of shale gas storage and transport, accurate characterization methods for 3D kerogen structures are attracting increasing attention. Spatial alignment is important information for 3D kerogen modeling, but was usually ignored in previous studies. In this work, seven kerogen samples with different maturities were isolated from organic-rich shale using a chemical method and high-resolution transmission electron microscopy (HRTEM) was employed to quantitatively characterize the spatial alignment of these seven kerogen samples. Raman spectroscopy was used to investigate the overall structural disorder of the kerogen molecules and Fourier transform infrared (FT-IR) was conducted to study the chemical structure of these kerogen samples. The results show that immature, mature, and overmature kerogen samples all show an obvious alignment on the scale of 20 nm × 20 nm. In the immature kerogen sample Yl-1 with equivalent vitrinite reflectance (VReqv) = 0.4%, 60% of total aromatic fringes align in the major direction (with a 60° range), while 87% of the total aromatic fringes align in the major direction for the overmature kerogen sample Lmx-3 (VReqv = 3.1%). However, unlike local alignment in the scale of 20 nm × 20 nm, the aromatic fringes in different regions may have different directions in larger scale. Meanwhile, based on FT-IR data, aliphatic carbons and oxygen containing functional groups contribute to a large proportion in immature, mature, and overmature kerogen samples. Thus, immature, mature and overmature kerogen samples all show overall disorder according to Raman data. In addition, the size of aromatic rings is also quantitatively characterized based on HRTEM images. In immature kerogen samples, the proportion of aromatic rings smaller than 3 × 3 is larger than 70%. In mature and overmature kerogen samples, 3 × 3 sized aromatic rings always occupy the largest proportion. This study provides the quantitative information on spatial alignment and the size of aromatic rings for kerogen samples, which contribute to an improved understanding of the 3D structure of kerogen.
Integrated CO2 capture, conversion and storage to produce calcium carbonate using an amine looping strategy Energy Fuels (IF 3.024) Pub Date : 2018-09-24 Meishen Liu, Greeshma Gadikota
One of the critical and emerging needs for sustainable energy production is the development of novel integrated approaches for the capture, conversion, and storage of CO2. In this context, carbon mineralization which is a thermodynamically downhill route for the accelerated conversion of CO2 to water insoluble and stable calcium and magnesium carbonates is a sustainable approach for permanently storing CO2. However, one of the challenges with carbon mineralization has been the need for higher concentrations of CO2 to accelerate the formation of calcium and magnesium carbonates. In this study, we propose a direct integrated approach in which amine-bearing solvents such as monoethanolamine (MEA) and alkaline Ca-bearing solids such as calcium oxide and calcium silicate are reacted in a slurry reaction system in two modes. These two modes involve in-situ changes in the aqueous chemistry to facilitate the capture of CO2 using MEA, and the release of CO2 into the aqueous phase to produce higher conversions of calcium carbonate. In the first mode, continuous CO2 flow at 1 atm is provided such that MEA in the aqueous phase captures CO2 and supplies the captured carbon-bearing species for reaction with dissolved calcium. In the second mode, MEA pre-loaded with CO2 was introduced into the system without a continuous supply of CO2. Complete conversion of calcium oxide to calcium carbonate was achieved using both modes. Further, the extent of carbon mineralization achieved with calcium silicate was 36% in Mode 1 as opposed to 20% in Mode 2 at 50 oC for a reaction time of 3 hours. These data suggested that amine-bearing solvents undergo continuous looping between the CO2 loaded and release states which facilitate the accelerated conversion of calcium-bearing oxides and silicates to calcium carbonate. The formation of calcium carbonate and calcium hydroxide phases was noted when less than complete conversions of calcium oxide were achieved. Calcium carbonate was the only phase formed on the complete conversion of calcium oxide and the carbon mineralization of calcium carbonate.
Effect of SO2 addition on PM formation from biomass combustion in an entrained flow reactor Energy Fuels (IF 3.024) Pub Date : 2018-09-24 Zhongfa Hu, Xuebin Wang, Renhui Ruan, Shuaishuai Li, Shengjie Bai, Jiaye Zhang, Houzhang Tan
The sulfation process during biomass combustion and co-firing, by converting KCl into K2SO4, can affect the particulate matter (PM) formation, ash deposition, and corrosion in furnace. In this study, the effects of temperature, SO2 concentration, O2 concentration and oxy-combustion atmosphere on the sulfation and PM formation were investigated in an entrained flow reactor. Results show that the particle size distribution (PSD) of PM10 from biomass combustion is bimodal, and the PM10 is dominated by PM1.0 consisting of KCl and K2SO4. Enhanced sulfation by SO2 addition generally increases the particle size of PM1.0 and the K2SO4 content in PM1.0, but its effect on PM1.0-10 is marginal. The effect of sulfation on PM1.0 formation strongly depends on the temperature: at high temperature (e.g., 1300 °C) the sulfation is not favorable, thereby has negligible influence on PM1.0 formation; while at moderate temperature (e.g., 1100 °C), the sulfation is significantly promoted, resulting in a larger size and higher yield of PM1.0. With the increase of the SO2 and O2 concentration, the particle size and the sulfur content in PM1.0 increase, indicating an enhanced sulfation process. When the combustion atmosphere switches from O2/N2 to O2/CO2, the PM1.0 emission increases while the sulfation process is inhibited. The comparison between the nucleation-growth modeling of KCl(g) and K2SO4(g) shows that the presence of K2SO4(g) advances the homogeneous nucleation, resulting in a longer residence time for particle growth, thereby a larger PM1.0 size.
Removal of toluene as a biomass tar surrogate in a catalytic non-thermal plasma process Energy Fuels (IF 3.024) Pub Date : 2018-09-21 Bin Xu, Jianjun Xie, Hao Zhan, Xiuli Yin, Chuangzhi Wu, Hao Liu
In this study, a packed-bed dielectric barrier discharge (DBD) reactor was developed to investigate the removal of biomass tar in a fuel gas atmosphere. Toluene was used as the tar surrogate and the catalyst used was a Nickel-based catalyst (Ni/γ-Al2O3) because of its high activity and low cost. In addition, other two kinds of packing materials (glass pellets and γ-Al2O3 pellets) were employed to make a comparison with the Ni/γ-Al2O3 catalyst. The research has focused on the removal efficiency of toluene and the effects of carrier gas, reaction temperature, Ni loading and concentration of toluene. The results indicated that two supplementary packing materials could not realize an effective removal of toluene. On the contrary, Ni/γ-Al2O3 combined with plasma showed a significant synergetic effect and hence a great toluene removal potential. On one hand, the removal efficiency initially decreased within the temperature range of 200 – 300 °C and then significantly increased within the temperature of 300 – 400 °C during plasma-catalytic process. At the optimal temperature of 400 °C, the toluene removal efficiency could reach the maximum values of 80.2 %, 91.7 % and 100.0 % when the Ni loading was 3, 5 and 10 wt%, respectively. On the other hand, an increase in the inlet toluene concentration slightly reduced removal efficiency but increased the energy efficiency, reaching the highest value of 16.8 g/kWh. The introduction of plasma enhanced the methanation reaction of the fuel gas occurring in the catalytic process, which was favorable at high temperatures. Based on these findings, the mechanisms and pathways of toluene destruction in the plasma-catalytic process were proposed and elucidated.
Combustion Behaviour of Single Pellets of Coal–Wood Mixtures in a Hot Gas Flow Field Energy Fuels (IF 3.024) Pub Date : 2018-09-21 CHINSUNG MOCK, Hookyung Lee, Seuk-Cheun Choi, Won Yang, Sangmin Choi, Vasilije Manovic
This experimental study explores the burning characteristics of single pellets made of wood and coal mixtures for co-firing. Three types of pellets were prepared with different wood to coal ratios (100:0, 80:20% and 50:50%). Experiments were carried out in a laboratory reactor at rapid heating rates and under oxygen concentrations between 10% and 40%. To investigate their combustion behaviour, a single pellet was suspended on a wire injected into a hot gas stream at 1340 K, and flame and char combustion were recorded through an observation window by means of a high-resolution (4K) camera. The sequential combustion time, volatile flame characteristics and mass reduction rate were obtained over a time profile by carefully controlled particle injection. The results demonstrated that the char combustion time increased significantly compared with the volatile combustion time, which only varied a little, when the pellets contained coal in the mixture. Partially detached flames were also predominantly observed on pure biomass pellets at oxygen concentrations between 21% and 40%. During the homogeneous combustion period, the cross-sectional area of a pellet shrunk by 26.3%–37.5%, depending on the type of pellet.
The mechanism and kinetics study of carbon dioxide absorption into methyldiethanolamine /1-hydroxyethyl-3-methylimidazolium lysine /water system Energy Fuels (IF 3.024) Pub Date : 2018-09-21 Wei Li, Shujing Wen, Li Shen, Yuchi Zhang, Cheng Sun, Sujing Li
In this work, the aqueous solutions of 1-hydroxyethyl-3-methylimidazolium lysine ([C2OHmim][Lys]) and methyldiethanolamine (MDEA) were developed to obtain an efficient absorbent for CO2 capture. The absorption performance, regeneration performance, reaction and kinetics mechanism of the blends were investigated. It was found the blended absorbents with molar ratio of 8:2 of MDEA to [C2OHmim][Lys] was the optimum ratio based on absorption rate, absorption capacity and other factors. The CO2 absorption capacity of the blends is 0.75 mol CO2 /mol IL and the absorption rate was higher than that of the aqueous MDEA solution. The regeneration efficiency of the blends was 93% after the third absorption-generation cycle, which was higher than the aqueous solutions of 1 mol/L MDEA (88%) or 1 mol/L [C2OHmim][Lys] (88%) under same conditions, indicating a better regeneration performance of the blends. The reaction mechanism and kinetics study of the CO2 absorption into the blends were investigated by 13C NMR and double stirred-cell absorber, respectively. [C2OHmim][Lys] in aqueous solution firstly formed carbamate with CO2, and the next step was hydrolysis of MDEA and partial carbamate, with the production of bicarbonate. It also found that the influence of temperature in the CO2 absorption was different in the two steps. Also, [C2OHmim][Lys] could promote the hydration reaction of MDEA and CO2 according to the chemical mechanism and kinetics study. The kinetics region was considered to be a fast pseudo-first order and the activation energy of the blends was 40.0 kJ mol-1.
Low-temperature and single-step synthesis of N-doped porous carbons with a high CO2 adsorption performance by sodium amide activation Energy Fuels (IF 3.024) Pub Date : 2018-09-21 Linli Rao, Limin Yue, Linlin Wang, Zhenzhen Wu, Changdan Ma, Liying An, Xin Hu
In this study, nitrogen doped porous carbons were prepared by a facile synthesis method at low temperatures ranging from 400-500°C. Sodium amide was used as both activator and nitridation reagent, and lotus stalk was used as the carbon precursor. The as-synthesized samples demonstrate the maximum CO2 uptake of 3.88 and 5.62 mmol/g at 25 and 0°C, respectively, at atmospheric pressure. Moreover, these lotus stalk-derived adsorbents exhibit high CO2/N2 selectivity, rapid CO2 adsorption rate, moderate CO2 isosteric heat of adsorption, stable cyclic ability and excellent dynamic CO2 capture capacity. Systematic research shows that besides the volume of narrow micropore and nitrogen content, the pore size distribution is also a non-negligible factor in determining CO2 adsorption capacity under ambient condition for these adsorbents. The good CO2 adsorption performance combined with single-step and low temperature preparation indicate that these sorbents are very promising for CO2 capture from flue gas.
Slag Formation during Entrained Flow Gasification: Silicon-Rich Grass Fuel with a KHCO3 Additive Energy Fuels (IF 3.024) Pub Date : 2018-09-21 Per Holmgren, Markus Broström, Rainer Backman
Prediction of ash particle adherence to walls, melting, and flow properties are important for successful operation of slagging entrained flow gasifiers. In the present study, silicon-rich reed canary grass was gasified at 1000 and 1200 °C with solid KHCO3 added at 0, 1, or 5 wt % to evaluate the impact and efficiency of the dry mixed additive on slag properties. The fuel particles collided with an angled flat impact probe inside the hot reactor, constructed to allow for particle image velocimetry close to the surface of the probe. Ash deposit layer buildup was studied in situ as well as ash particle shape, size, and velocity as they impacted on the probe surface. The ash deposits were analyzed using scanning electron microscopy–energy-dispersive X-ray spectroscopy, giving detailed information on morphology and elemental composition. Results were compared to thermodynamic equilibrium calculations for phase composition and viscosity. The experimental observations (slag melting, flow properties, and composition) were in good qualitative agreement with the theoretical predictions. Accordingly, at 1000 °C, no or partial melts were observed depending upon the potassium/silicon ratio; instead, high amounts of additive and a temperature of at least 1200 °C were needed to create a flowing melt.
Asphaltenes Precipitation Onset: Influence of the Addition of a Second Crude Oil or Its Asphaltenes Fractions (C3I and C5I) Energy Fuels (IF 3.024) Pub Date : 2018-09-20 Fabio R. Barreira, Leidiane G. Reis, Rita de Cassia P. Nunes, Sofia D. Filipakis, Elizabete F. Lucas
Predicting the asphaltene stability in crude oils from different production streams is very useful in the petroleum industry because it allows avoiding serious problems caused by formation of solid deposits during oil flow. That prediction can be carried out by applying the solubility parameter (δ) of each oil, as calculated by the asphaltene precipitation onset value, obtained by titration with n-heptane. However, many crude oils do not have a well-defined precipitation onset point, which can be overcome by adding a crude oil assumed as the standard. This article analyzes the influence of a crude oil (called APS) on the precipitation onset of two other petroleum samples (called APA and APB). For this purpose, the asphaltene fractions C3I and C5I were extracted from APS, and the influence of the addition of this crude oil as well as its asphaltenes fractions in samples of oils APA and APB was evaluated by tests involving titration of n-heptane with detection by near-infrared spectroscopy (NIR). The calculation of the solubility parameters of the oils without well-defined precipitation onset, by adding the oil with well-defined precipitation onset, led to varied errors in function of the type of oil in question. The smallest errors were obtained when using, as the solubility parameter of the mixture (δM), the solubility parameter of the solvent system at the precipitation onset of the asphaltene C3I fraction (extracted from the crude oil assumed as the standard) in toluene, determined by titration with n-heptane.
Highly Efficient and Reversible Capture of Low Partial Pressure SO2 by Functional Deep Eutectic Solvents Energy Fuels (IF 3.024) Pub Date : 2018-09-20 Yang Chen, Bin Jiang, Haozhen Dou, Luhong Zhang, Xiaowei Tantai, Yongli Sun, Haiming Zhang
Influence of Biomass Ash Additive on Reactivity Characteristics and Structure Evolution of Coal Char–CO2 Gasification Energy Fuels (IF 3.024) Pub Date : 2018-09-20 Juntao Wei, Yan Gong, Lu Ding, Junqin Yu, Guangsuo Yu
In this study, the influence of biomass ash (rice straw ash, RSA) additive on char gasification reactivity of different rank coals (Shenfu bituminous coal and Zunyi anthracite) was investigated using thermogravimetric analysis. Moreover, the structure characteristics (i.e., the chemical forms and concentrations of AAEM species and the order degree of carbon structure) of gasified semichars were quantitatively studied to evaluate the effect of RSA additive on coal char structure evolution during gasification. Specific reactivity index was proposed as a quantitative index and showed that RSA additive facilitated coal char gasification, especially at lower gasification temperature and for high-rank coal char. In addition, the results from the active AAEM concentrations and the Raman band area ratios of gasified semichars indicate that the RSA additive was conducive to the increase of active AAEM concentrations in coal char and the decrease of the degree of graphitization of coal char carbon structure during gasification, which were more significant at lower temperature and for high-rank coal char. It could be concluded from these results that the function mechanism of the RSA additive on coal char gasification reactivity had a close relationship with char structure evolution during gasification. Kinetics analysis using isoconversional method demonstrated that the gasification activation energy of Shenfu and Zunyi coal char with RSA additive were respectively lower than those of the corresponding coal chars by 8.33 and 22.32 kJ mol–1, indicating that the RSA additive was favorable for activation energy reduction of coal char gasification, especially for high-rank coal char. This work verified the possibility of promoting coal gasification using biomass ash as a natural catalyst and revealed the function mechanism of biomass ash additive on coal char gasification.
Adsorbent from Rice Husk for CO2 Capture: Synthesis, Characterization, and Optimization of Parameters Energy Fuels (IF 3.024) Pub Date : 2018-09-20 Premanath Murge, Srikanta Dinda, Sounak Roy
In the present work, adsorbents were prepared from rice husk in order to capture CO2 from a flue gas stream. Various pretreatment processes such as desilicalization, chemical activation, and K2CO3 impregnation were followed to prepare the adsorbents. The physico-chemical characterization of the adsorbents was performed in detail in an elaborated way. A fixed-bed reactor was used to measure the CO2 capture capacity of the in-house developed adsorbents. The effect of various process parameters such as adsorption temperature, moisture content, and loading of active component on CO2 adsorption capacity was studied, and results were compared with a commercially available activated carbon. The maximum adsorption capacity observed for 20K-ARH adsorbent was as high as 67 g of CO2/kg sorbent. The effect of water on CO2 adsorption was critically examined, and formation of KHCO3 was observed in the presence of water during the adsorption process. The optimum operating conditions for the maximum removal of CO2 from a simulated flue gas include a temperature range of 30–40 °C, relative humidity range of 80–90%, and K2CO3 loading of about 20 wt %. It was observed that around 94% of the adsorbed CO2 can be desorbed at 180 °C, and the adsorbent can be reused for multiple cycles without compromising the capture capacity significantly.
Effect of Catalyst Deactivation on the Energy Consumption of Gasoline–Diesel Hydrotreating Process Energy Fuels (IF 3.024) Pub Date : 2018-09-20 Xiao Tian, Changfang Yin, Donghui Lv, Peng Wang, Guilian Liu
The effect of catalyst activity on a 900 000 ton y–1 gasoline–diesel hydrotreating unit is analyzed on the basis of the integration of hydrotreating reactor and the heat exchanger network (HEN). The reactor’s inlet/outlet temperatures versus catalyst activity relation is identified on the basis of simulation and coupled with the composite curve. On the basis of this, a graphical method is proposed to integrate the hydrotreating reactor and the HEN, and analyze the effect of catalyst deactivation on the energy consumption of HEN. Three matching schemes are proposed for the HEN, and the variations of the heat exchange area along the catalyst deactivation are analyzed. The optimal matching scheme is identified with both operating cost and capital cost considered. For the studied gasoline–diesel hydrotreating unit, catalyst deactivation has a significant influence on the energy consumption, and the minimum heating utility consumption decreases from 2680 kW to 0 as the catalyst activity decreases from 0.9 to 0.44. The study shows that the heat exchange area of a heat exchanger changes significantly along catalyst activity, and its maximum area might appear at neither the highest nor the lowest catalyst activity. The proposed integration method can be applied to analyze the effect of catalyst deactivation efficiently.
Differences in the Fluid Characteristics between Spontaneous Imbibition and Drainage in Tight Sandstone Cores from Nuclear Magnetic Resonance Energy Fuels (IF 3.024) Pub Date : 2018-09-20 Meng Chen, Jiacai Dai, Xiangjun Liu, Minjun Qin, Yang Pei, Zhongtao Wang
As the water injected during hydraulic fracturing is imbibed and then displaced in the matrix of tight reservoirs, it is meaningful to characterize the fluid distributions and percolation dynamics during these two processes as they significantly affect production. In this study, 6 tight sandstone cores from the Chinese Ordos Basin were selected to experimentally study the fluid seepage and distributions during spontaneous imbibition and drainage using a low-field nuclear magnetic resonance (NMR) core analysis unit. Dry cores were first tested via co-current imbibition and then centrifuged from fully saturated to irreducible water saturation to simulate the imbibition and drainage processes, respectively. The weights and T2 spectra were measured concurrently for each step. The results showed that the volume of imbibed water increased rapidly during the first 3,000 min and reached a constant value at the end of the experiment; the final imbibition water saturation Swim ranged from 48.52 to 89.20%. The irreducible water saturation Swir was reached after a centrifuge speed of 10,000 r/min and varied from 40.46 to 53.28%. The gas and water relative permeabilities were estimated by combining the T2 spectra for different water saturations, which indicated the effect of the capillary force and pore-throat structure on the different fluid seepage characteristics during spontaneous imbibition and drainage. The T2 time was converted to the corresponding pore-throat radius by combining the fully water-saturated T2 spectra and pore distributions from a constant-rate mercury injection. Micropores of 0~2 μm were identified as the dominant pore spaces for imbibed water during spontaneous imbibition, and the water remained after centrifugation, whereas a small amount of water was imbibed or remained in pores larger than 20 μm. The physical properties, microstructure and dispersed clay minerals were considered to be the three dominant factors of the fluid dynamics and distribution differences, and the effects were stronger during spontaneous imbibition.
Effects of chlorine in ash on the corrosion performance of Ni-based alloys in simulated oxy-fuel environment Energy Fuels (IF 3.024) Pub Date : 2018-09-20 Zuotao Zeng, Ken Natesan, Zhonghou Cai, David J Gosztola
Alloy materials can be severely degrade by corrosive gases and coal ash in service of coal power plant at high temperature. To better understand alloy corrosion in coal power plant, it is necessary to study the effect of each constituent from coal combustion on alloy corrosion. Chlorine-containing compounds in coal are corrosion-accelerating agents. The concentration of chlorine increases a lot in gas environment of oxy-fuel combustion due to the absence of airborne nitrogen gas acting as a diluent. The role of chlorine in ash corrosion is investigated in simulated oxy-fuel environments. Long time tests over 3000 hours were performed on various alloys at 750○C. The degradation depth, weight change, and microstructural characteristics of oxide scales on Ni-based alloys are reported after exposure at 750○C in oxy-fuel combustion environment for over 3000h. Synchrotron nanobeam X-ray analysis was performed to evaluate the phase and chemical composition of the oxide layers on the alloy surface. Nanobeam X-ray and SEM analyses indicate that chlorine can modify the diffusion mechanism near alloy surface, thereby, increase corrosion rate.
Effect of Silane Capping on the Dispersion and Combustion Characteristics of Sub-Micron Boron Particles Loaded in Jet A-1 Energy Fuels (IF 3.024) Pub Date : 2018-09-20 Pawan Kumar Ojha, Srinibas Karmakar
The present investigation deals with the surface modification of sub-micron boron particles with octadecyltrimethoxysilane (a silane compound) in order to improve the dispersion stability of boron particles in liquid fuel. Characterizations of as-received and silane-coated boron particles in terms of particle size, morphology, surface chemistry, ignition temperature, and oxidation profile have been conducted using typical material characterization methods such as SEM, STEM, XPS and TGA. The results show that the surfaces of as-received boron particles have been successfully functionalized via condensation reaction of hydroxyl function groups (-OH) with octadecyltrimethoxysilane (OTMS) molecules. The capping of OTMS on boron surface makes the particle stable against air oxidation. The dispersion stability of OTMS-capped boron in Jet A-1 at particle loading of 1%, 5% and 10% are found out to be 20 hours, 18 hours and 2 hours respectively. Ignition and combustion characteristics of as-received and silane-coated boron particles loaded in Jet A-1 at desired concentrations have been analyzed to understand the effect of silane coating. TGA, true colour flame images and spectroscopic results show that the burning process of OTMS-capped boron is slightly delayed compared to as-received boron. The droplet diameter regression profiles show smooth regression up to 70-80% of droplet lifetime with some intermittent puffing with disruptions at later stage in both the particle cases. However, the intensity of disruption is stronger in case of OTMS-capped boron because of the formation of more compact shell inside the droplet due to the melting of OTMS layer (particularly towards the end of droplet lifetime). The micrographs of combustion residue reveal that some tiny holes are present on the residue surface in case of as-received boron whereas multiple blow holes are there in case of OTMS-capped boron. A blanket of silicon seems to cover the particle surface which makes them to stick together.
Experimental Study on Mercury Adsorption and Adsorbent Regeneration of Sulfur-Loaded Activated Carbon Energy Fuels (IF 3.024) Pub Date : 2018-09-20 Na Li, Hongqi Wei, Yufeng Duan, Hongjian Tang, Shilin Zhao, Peng Hu, Shaojun Ren
A kind of commercial sulfur-loaded activated carbon (SAC) was experimentally studied on the mercury adsorption and adsorbent regeneration performance. Mercury adsorption experiments were carried out on a bench-scale fixed-bed experimental device. The physicochemical properties of the original and used SAC were characterized and discussed based on surface area and porosity (Brunner-Emmet-Teller measurements, BET) and X-ray photoelectron spectroscopy (XPS) analysis. The results showed that the specific surface areas andthe content of oxygen functional groups as well as non-oxidized sulfur on the surface decreased after mercury adsorption. The used samples were regenerated via the co-pyrolysis with elemental sulfur. The regenerated adsorbent showed an average mercury removal efficiency up to 95% in two hours under the condition of co-pyrolysis temperature at 600℃, one hour heating-up time and sulfur-carbon ratio of 1:1. The regenerated sample was found to be structurally stable and sustainably reactive on the Hg0 capture within five cycles. The mercury adsorption capacity still maintained 291.22 ug/g after five cycles. The sulfur-loaded activated carbon with the adsorbent regeneration method will provide a database for developing the renewable mercury adsorbent applied in the injecting demercuration technology in flue gas of the coal-fired power plants.
Rheological behavior of surface modified silica nanoparticles dispersed in Partially Hydrolyzed Polyacrylamide and Xanthan Gum solutions: Experimental measurements, mechanistic understanding, and model development Energy Fuels (IF 3.024) Pub Date : 2018-09-20 Laura M. Corredor-Rojas, Abdolhossein Hemmati Sarapardeh, Maen M. Husein, Prof. Mingzhe Dong, Brij B. Maini
Polymer solutions are designed to develop a favorable mobility ratio between the injected polymer solution and the oil-water bank being displaced by the polymer. Subsequently, a more uniform volumetric sweep of the reservoir is produced. Chemical and mechanical degradation of the polymer solutions, on the other hand, reduce their viscosity which significantly affects their performance. The primary objective of this study is to investigate the effect of surface modification of silica nanoparticles (NPs) on the effective viscosity of partially hydrolyzed polyacrylamide (HPAM) and xanthan gum (XG) solutions at different NP concentrations and temperatures. The chemical functionalization of SiO2 NPs with carboxylic acids and silanes was confirmed by FTIR measurements. The experimental results showed that the addition of SiO2 NP increased the viscosity of XG solutions due to the formation of three-dimensional structures between the silica NPs and the polymeric chains. The thickening effect of HPAM was improved by the addition of silica NPs modified with 3-(Trimethoxysilyl) propyl methacrylate (MPS), Octyl triethoxy silane (OTES), and Oleic Acid-method A (OAA). In addition, the HPAM and XG nanopolymer sols of modified silica NPs showed more temperature and brine tolerance than that of unmodified silica NPs. A model was developed based on multilayer perceptron (MLP) neural network for predicting viscosity of nanopolymer sols using 9900 data points. The MLP model was trained by Bayesian Regularization (BR), Levenberg-Marquardt (LM), Resilient Backpropagation (RB), and Scaled conjugate gradient (SCG) algorithms. The results revealed that the BR-MLP model outperformed the three other models and could predict all the viscosity data with an average absolute relative error of 2.46% and R2 of 0.999.
Measurements of Pressure Effects on PAH Distribution and 2D Soot Volume Fraction Diagnostics in a Laminar Non-premixed Coflow Flame Energy Fuels (IF 3.024) Pub Date : 2018-09-19 Anthony Bennett, Hafiz M. F. Amin, Emre Cenker, William L. Roberts
The soot formation process has been investigated at pressures up to 16 bar using a non-premixed laminar coflow flame with nitrogen-diluted ethylene. 2D diffuse line-of-sight attenuation (2D LOSA) and planar laser-induced incandescence (PLII) were used to measure soot volume fraction (SVF). The peak SVF increased exponentially with increasing pressure, and the spatial distribution of soot volume fraction changed substantially. At pressures below 6 bar, the two techniques agreed well. At pressures above 6 bar, the techniques began to disagree, with 2D LOSA showing higher peak SVF values at a location lower in the wings of the flame compared to PLII. Errors in the LOSA measurements due to the molecular absorption of PAHs were assessed by performing measurements with bandpass filters centered at 435 nm and at 647 nm. Furthermore, the evolution of polycyclic aromatic hydrocarbons (PAH) in the flame was studied using planar laser-induced fluorescence (PLIF) with the excitation laser set at 282.85 nm and compared to LOSA measurements. Fluorescence signals were captured using bandpass filters (350, 400, 450, and 510 nm) corresponding to increasing PAH size. The peak concentration of PAHs moved closer to the burner nozzle as pressure increased. Absorption by PAH was unable to explain discrepancies between LOSA measurements and PLII measurements. Using the Rayleigh–Debye–Gans approximation for polydisperse fractal aggregates (RDG-PFA), the differences between LOSA and PLII measurements were analyzed, and it was found that LOSA is more sensitive to the soot primary particle diameter due to changes in the scattering-to-absorption ratio (ρsa). The effect of gate duration on SVF imaging with PLII is also reported.
Integrated Particle- and Reactor-Scale Simulation of Pine Pyrolysis in a Fluidized Bed Energy Fuels (IF 3.024) Pub Date : 2018-09-18 M. Brennan Pecha, Emilio Ramirez, Gavin M. Wiggins, Daniel Carpenter, Branden Kappes, Stuart Daw, Peter N. Ciesielski
Evolution Law of Adsorption and Desorption Characteristics of CH4 in Coal Masses during Coalbed Methane Extraction Energy Fuels (IF 3.024) Pub Date : 2018-09-18 Zongqing Tang, Shengqiang Yang, Guang Xu, Mostafa Sharifzadeh, Cheng Zhai
The low-temperature oxidation of coal during coalbed methane extraction is inevitable. To study the evolution of the CH4 adsorption and desorption characteristics in coal masses during the low-temperature oxidation of coal, starting from the evolution of physical and chemical adsorption of CH4 in coal masses during the low-temperature oxidation of coal and combining it with the evolution of free radicals, we constructed a physical model of CH4 adsorption and desorption in the coalbed methane extraction process. This model provides the theoretical basis for improving the efficiency and quantity of coalbed methane extraction. Our results indicate that during coalbed methane extraction, the mesopores, macropores, and overall porosity increase with the rise in oxidation temperature. However, the number of micropores first increases and then decreases during the process, leading to the CH4 physical adsorption capacity showing a trend of first increasing and then decreasing with increasing oxidation temperature; however, the number of −COOH groups shows the opposite trend to that of the number of micropores, resulting in the CH4 chemical adsorption capacity first decreasing and then increasing with the increase of the oxidation temperature; meanwhile, the free radical content increases gradually with the increasing oxidation temperature, leading to the continuous consumption of O2 adsorbed on the coal surface and the reinforcement of the CH4 adsorption capacity. To maximize coalbed methane extraction efficiency, it is necessary to take measures to avoid the low-temperature oxidation of coal at the initial stage.
Comprehensive Utilization for Neogene Lignite of the Zhaotong Basin, South China, and Its Environment Impacts Energy Fuels (IF 3.024) Pub Date : 2018-09-18 Jie Long, Shixi Zhang, Kunli Luo
Neogene lignite is widely used for enterprise’s electric power generation, local residents’ warming and cooking, and crops’ fertilizer in South China nowadays. But there is still no report about the element variations in Neogene lignite from the Zhaotong Basin, South China. Understanding the elemental concentration in lignite is of great importance to comprehensive utilization and to evaluation of environmental impacts of the Neogene lignite. We studied the variation patterns of 34 elements in lignite samples collected from the Neogene Zhaotong Formation at Zhaotong Basin, Yunnan Province, China. The arithmetic average of Cr, V, Ga, As, Cu, Rb, Co, Mo, and Cd in studied lignite samples is higher than those of China coals, while the content of Li and Bi are lower. Contents of As, Rb, La, Ni, Cd, Mo, Co, Ga, and V in northeastern Yunnan lignite are higher than the corresponding elements in common American Texas lignite, while contents of Li and Bi are lower. Elements are classified into four groups (Si–K–Zn–Rb–Ba–Pb, Co–Cd–Na–Al, Ni–Ti–Bi–Cr–Cu–In–Mn–Mg-Ga–Fe–Tl, and V–U–Cs–Sc–La–Sr–L–Se–Ca–As–Mo-S) based on their correlation coefficient with ash yield. Elements, including Al, K, Na, Si, Ti, Ba, Bi, Cd, Cr, Cu, Cs, Co, Ga, Ni, Sc, Zn, and Pb, decrease from bottom to top of the Neogene Zhaotong Formation, whereas Ca, Mg, As, Se, Mo, Fe, and S increase. In addtion, in M2 and M3 coal-bearing beds, Ga has potential applications after recycling and Se could be reutilized as a kind of Se-containing fertilizer, and their reserves estimations are approximately 98 × 104 (Ga) tons and 7.8 × 104 tons (Se). Cr and Cd in Neogene lignite have potential risk for local natural environments and the health of human beings.
Influence of Reaction Temperature on the Interpretation of Delplots for the Parallel-Series Reaction Network Energy Fuels (IF 3.024) Pub Date : 2018-09-18 Nabeel S. Abo-Ghander, Michael T. Klein
The use of Delplots to deduce the key features of reaction networks using nonisothermal kinetics data was examined. Using Delplots, a product’s network rank, i.e., the number of reaction steps required for its formation from a specified reactant “A,” is generally obtained by extrapolating plots of yi/xAr vs xA to xA = 0, where at isothermal conditions, contact time was varied to provide the range of conversion supporting the extrapolation. The presently described work addressed the common experimentalists’ technique of using temperature, rather than contact time, to provide the range of conversion. To assess any uncertainties thus introduced, the effect of changing the temperature of kinetic measurements has been addressed for the parallel-series reaction network ; with B0 = 0. The relative activation energies of the key reactions were varied by ±6 kcal/mol with respect to that for k1, and temperature was varied between 200 and 1000 K. The resulting Delplot information can appear to suggest different reaction networks if the activation energy difference is too large and the temperature range too wide. The Delplot method classifies species B to be a primary product at low temperature when E2 > E1, while it appears to be a secondary product when E2 < E1. We suggest, as rough guidelines, that varying temperature to provide variations in conversion in the kinetic study is reasonable for E1 ∼ 50 kcal/mol if the activation energy difference E21 is in between 3 and −3 kcal/mol.
Molecular Dynamics Simulation of the Salinity Effect on the n-Decane/Water/Vapor Interfacial Equilibrium Energy Fuels (IF 3.024) Pub Date : 2018-09-18 Jin Zhao, Guice Yao, Srinivasa B. Ramisetti, Robert B. Hammond, Dongsheng Wen
Low-salinity water flooding of formation water in rock cores is, potentially, a promising technique for enhanced oil recovery (EOR), but details of the underlying mechanism remain unclear. The salinity effect on the interface between water and oil was investigated here using the Molecular Dynamics (MD) simulation method. n-Decane was selected as a representative oil component, SPC/E water and OPLS-AA force fields were used to describe the water/oil/ionic interactions for salt water and n-decane molecules. Equilibrium MD simulations were firstly conducted to study the n-decane/vapour and salt-water/vapour interface systems at six different NaCl concentrations (0 M, 0.05 M, 0.10 M, 0.20 M, 0.50 M and 1.00 M). The water/oil interface was then investigated by calculating bulk density distribution, radial distribution function, interface thickness and water/oil interfacial tension (IFT). Sufficiently long MD simulations of water/n-decane/vapour were performed, followed by an analysis of the effect of salinity on the water/oil/vapour interface. The IFT values for the water/vacuum interface, n-decane/vacuum interface and water/n-decane interface were obtained from the pressure tensor distribution after system equilibration, with values of 71.4, 20.5 and 65.3 mN/m, respectively, which agree well with experimental and numerical results reported in the literature. An optimal salinity of ~0.20 M was identified corresponding to a maximum interfacial thickness between water and oil phase, which results in a minimum water/oil IFT value and a maximum value for the oil/water contact angle, a condition beneficial for enhanced oil recovery.
Effect of Acid-washing on the Nature of Bulk Characteristics of Nitrogen-doped Carbon Nanostructures (CNx) as Oxygen Reduction Reaction (ORR) Electrocatalysts in Acidic Media Energy Fuels (IF 3.024) Pub Date : 2018-09-18 Kuldeep Mamtani, Deepika Singh, Doruk Dogu, Deeksha Jain, Jean-Marc M Millet, Umit S. Ozkan
CNx catalysts were synthesized using Fe-doped MgO as a growth substrate. The ORR performance of the synthesized samples was evaluated in half-cell. Acid-washing improved the ORR activity for the synthesized CNx samples. This is attributed to the removal of the exposed metal, which is likely to be blocking the active sites. Characterization experiments suggest that acid-washing totally eliminates the support material (MgO) and renders carbon more graphitic. This is likely to be due to elimination of amorphous or less crystalline species during washing. In-addition, characterization experiments reveal significant differences in the metallic species which are exposed vs. those encased in the carbon nanostructure
Characteristics of Lacustrine Shale Reservoir and its Effect on Methane Adsorption Capacity In Fuxin Basin Energy Fuels (IF 3.024) Pub Date : 2018-09-18 Daye Chen, Jinchuan Zhang, Xiaoming Wang, Bo Lan, Zhen li, Tong Liu
Abstract ：Lower Cretaceous Sahai and Jiufotang formation in Fuxin Basin, northwest Liaoning Province,,with stable planar distribution contain abundant shale gas reserves, which are the key horizons for the exploration breakthrough of the Mesozoic continental shale gas in northeastern China. Well Fuye1 drilled recently is an important shale gas parameter well in this area. A total of 43 shale samples were collected from Shaha and Jiufotang Formation of FuYe-1 Well at the depth of between 1157-2762m. A series of experiments, including organic matter vitrinite reflectance, XRD diffraction analysis, total carbonate content (TOC) measurement, scanning electron microscopy, low-temperature nitrogen adsorption and methane isothermal adsorption, were conducted in the samples and the results revealed that in Well FuYe-1, the shale of Lower Cretaceous Sahai and Jiufotang formation have a maturity of 0.46-1.68%, (average 0.92%), which was at immature-high maturity stage. The kerogen are mostly II-III type. The mineral components are dominated by clay minerals and quartz, (average 21.39% and 30.89% ), respectively. The main controlling factors of methane adsorption capacity were TOC content, total clay content and shale pore structure. Langmuir’s volume (VL) of the shale was 0.17～1.98m3/t, average 1.21m3/t. The methane adsorption capacity was positively correlated with the content total clay minerals and quartz, but varies in different clay minerals. The specific surface area of the shale and total pore volume are calculated by BET and BJH, the macro-pores ratio of which were negatively correlated with methane adsorption capacity, whereas the specific surface area and total pore volume of the mesopores and micropores ratio were positively correlated with methane adsorption capacity, indicating the content of micro-pores and mesopores was the major contributor to the specific surface area of shale.
Tetraethylammonium Amino Acid Ionic Liquids and CO2 for Separation of Phenols from Oil Mixtures Energy Fuels (IF 3.024) Pub Date : 2018-09-18 Youan Ji, Yucui Hou, Shuhang Ren, Congfei Yao, Weize Wu
Phenols have wide applications and much commercial value, and they are obtained from oil mixtures by separation. However, the previous separation agents have low separation efficiency or corrosive halide ions or difficult to be regenerated. In this work, we designed several tetraethylammonium amino acid (TAAA) ionic liquids (ILs) without corrosive halide ions, and found that the ILs could separate phenols from oil mixtures with much high extraction efficiency and could be regenerated using CO2. The effects of separation time, initial phenol content, TAAA type, water content in TAAA, and phenols’ type on separation were investigated. It has been found that TAAA can separate phenols with high separation efficiencies and the maximum separation efficiency of phenol can reach up to 99.0% at a TAAA:phenol mole ratio of 0.60. Meanwhile, ultimate phenol contents can reach as low as 1.40 g/dm3. The initial phenol content almost has no influence on the ultimate phenol contents. For real coal tar oil mixture, the separation efficiency of phenols can reach up to 98.6%. The TAAAs can be regenerated and reused without significant decreases in separation efficiency of phenols. The separation mechanism has also been proposed based on chemical reactions.
Effects of SO2 on Hg Adsorption by Activated Carbon in O2/CO2 Conditions. Part 1: Experimental and Kinetic Study Energy Fuels (IF 3.024) Pub Date : 2018-09-18 Hui Wang, Yufeng Duan, Zhanfeng Ying, Yuan Xue
Activated carbon was evaluated in the O2/CO2 conditions to explore effects of SO2 on the mercury adsorption. The pseudo–first–order kinetic model and intraparticle diffusion kinetic model were used to analyze the kinetic mechanism of mercury adsorption process. The experimental results revealed that SO2 promoted the mercury breakthrough rate in the similar O2/CO2 conditions compared with that without SO2. The inner relationship between SO2 concentration and external mass transfer rate had been investigated. The pseudo–first–order kinetic model described the process of mercury adsorption by activated carbon better compared with the intraparticle diffusion kinetic model. The external mass transfer rate was the main rate–control step in this experimental condition. All those findings are very important for mercury control by sorbents under oxy fuel combustion.
Mechanochemical synthesis of tannic acid-Fe coordination compound and its derived porous carbon for CO2 adsorption Energy Fuels (IF 3.024) Pub Date : 2018-09-18 Chao Cai, Ning Fu, Ziwei Zhou, Mengchen Wu, Zhenglong Yang, Rui Liu
Tannic acid-Fe coordination compound has been prepared via a simple mechanochemical method. The compound could be used as precursors for the fabrication of porous carbon, which was successfully applied as adsorbent for CO2 capture. The obtained porous adsorbent, NFePC-10-A, exhibited relatively high CO2 uptake capacities of 5.8 and 3.4 mmol g−1 at 0 and 25 °C, respectively. In addition, the initial isosteric heat of adsorption and selectivity for CO2/N2 were as high as 63.16 kJ mol-1 and 22.7 (0 °C). Meanwhile, the adsorbent underwent an efficient reusability, indicating a good potential for practical use. This feasible strategy might provide a novel precursor for the large-scale production of bio-derived carbonaceous adsorbents with tailored texture and porosity for CO2 capture and storage.
Efficient absorption of SO2 by [Emim][Cl]-[Emim][SCN] ionic liquid mixtures Energy Fuels (IF 3.024) Pub Date : 2018-09-18 Dezhong Yang, Ge Cui, Meng Lv
The SO2 absorption capacities of two ionic liquid mixtures formed by 1-ethyl-3-methylimidazolium chloride ([Emim][Cl]) and 1-ethyl-3-methylimidazolium thiocyanate ([Emim][SCN]) were studied. The ionic liquid mixtures with different molar ratios of [Emim][Cl] and [Emim][SCN] (1:1 and 1:2) can be easily synthesized. The SO2 solubility in the two mixtures was investigated under different conditions. The results demonstrated that these mixtures were efficient for SO2 absorption. The [Emim][Cl]-[Emim][SCN](1:1) captured 0.50 g/g solvent at 20C and 0.10 atm. Under the low SO2 partial pressure (1960 ppm), the [Emim][Cl]-[Emim][SCN](1:1) could capture 0.11g/g solvent. The high SO2 absorption capacity is mainly due to the strong charge-transfer interaction of the sulfur atom of SO2 with the anions ([Cl]- and [SCN]-). Moreover. the solvent [Emim][Cl][SCN](1:1) can be reused.
Low pressure methane storage in pinecone-derived activated carbons Energy Fuels (IF 3.024) Pub Date : 2018-09-18 Sara Stelitano, Giuseppe Conte, Alfonso Policicchio, Alfredo Aloise, Giovanni Desiderio, Raffaele Giuseppe Agostino
The methane adsorption properties of activated carbon samples from pinecones using chemical activation with different KOH/precursor ratio were evaluated at room temperature (298K) and pressure up to 35 bar using a volumetric Sievert type apparatus. A comprehensive characterization of different activated carbon samples was carried out by means of nitrogen adsorption/desorption measurements at liquid nitrogen temperature (77K), for the textural properties analysis, by Scanning Electron Microscopy and X-ray Diffraction for topography and long-range order estimation, by wavelenght-dispersive spectrometry for chemical composition, respectively. All the adsorption data were evaluated by Langmuir/Tóth isotherm model with a very high accuracy. The probed activated carbon samples show both higher methane storage values for pressure up to 35 bar and totally reversible methane uptake up to many cycles without any treatment in between indication of very stable properties. These results represent the starting point for an alternative method to the natural gas storage through the use of eco-compatible nanostructured materials.
Bifunctional MoS2-Silica-Alumina Catalysts for Slurry Phase Phenanthrene-Decalin Hydroconversion Energy Fuels (IF 3.024) Pub Date : 2018-09-18 Juliana Sanchez, Andres Moreno, Fanor Mondragon, Kevin J. Smith
MoS2-amorphous silica-alumina (MoS2-ASA) bifunctional catalyst for slurry-phase hydroconversion of the model reactants phenanthrene and decalin, were prepared using three distinct methodologies. The MoS2-ASA catalysts were prepared by: (i) a mechanical mixture of MoS2 (prepared separately) and ASA which were mixed directly in the reactor for the hydroconversion test (MM catalyst); (ii) in situ sulfidation of the molybdenum precursor in the presence of the ASA, both dispersed in the phenanthrene-decalin reaction mixture (IS catalysts) and (iii) impregnation of molybdenum octoate onto ASA, followed by thermal treatment to chemically link the Mo precursor to the ASA surface followed by sulfidation prior to the catalytic test (IMP catalyst). Among the three preparation methods, the MoS2-ASA catalysts prepared in situ (IS) had the highest MoS2 dispersion, degree of sulfidation and yielded the highest hydrogenating activity at the lowest Mo catalyst content (2.9Mo-ASA). Although, the MoS2 blocked Brønsted acid sites decreasing the ASA acidity, especially in IS and IMP catalysts, at the low Mo concentrations required with the IS methodology, most of the acidity was retained. In addition, in the case of IS catalysts, MoS2 particles were also found dispersed in the slurry feed independently of the ASA. Consequently, the IS catalyst retained the advantages of the unsupported MoS2 with the additional functionality of the acid component of the bifunctional catalyst, hence conversion was promoted due to both hydrogenation and hydrocracking reactions. These observations suggested that the bifunctional MoS2-ASA catalysts prepared in situ promotes hydrocracking reactions at lower temperatures reducing the severity of reaction conditions and limiting coke formation in slurry-phase hydroconversion.
Combustion of Sewage Sludge: Kinetics and Speciation of the Combustible Energy Fuels (IF 3.024) Pub Date : 2018-09-18 Jonas Wielinski, Christoph Müller, Andreas Voegelin, Eberhard Morgenroth, Ralf Kaegi
Combustion of sewage sludge has become a viable route for sewage sludge management especially as the agricultural use of sewage sludge has become increasingly difficult due to more stringent requirements regarding the quality of sewage sludge. Combustion of digested sewage sludge in dedicated monocombustion facilities is advantageous, as it substantially reduces the volume of the sludge and still allows for a recovery of phosphorus from the sewage sludge ash at a later stage. Despite increasing amounts of sewage sludge being combusted, knowledge on the respective combustion kinetics is still fragmentary. The goal of this study was, therefore, to identify the major combustion reactions of sewage sludge, assess their Arrhenius parameters (activation energy and pre-exponential factor), and assign suitable reference compounds to the individual reactions. For that purpose, experiments were conducted using a thermogravimetric analyzer (TGA). With matrix inversion, we identified 10 individual reactions. Despite the apparent kinetic compensation most likely caused by insufficient precision of the TGA temperature setting, we were able to relate the major reactions of sewage sludge combustion to the combustion of individual reference compounds. In addition to cellulose and lignin, which dominated the weight loss with 35% and 20%, respectively, hemicellulose, xylan, alginate, and calcite were identified. The dominant fraction of cellulose is consistent with recent studies identifying cellulose mainly originating from toilet paper as a major organic constituent in wastewater. As the identified model compounds explain more than 80% of the total weight loss observed, our approach allows a rough speciation of the combustibles of sewage sludge based on TGA experiments.
Simulating Thermal Wood Particle Conversion: Ash-Layer Modeling and Parametric Studies Energy Fuels (IF 3.024) Pub Date : 2018-09-18 Inge Haberle, Nils Erland L. Haugen, Øyvind Skreiberg
In this work, we study the thermochemical degradation and char conversion of wet wood particles. The work is split in two main parts: (1) the effect of the ash layer handling approach and (2) a parametric study over different relevant parameters. In the study of the ash layer handling, we investigate the effect of allowing the ash to remain on the surface of the particle when the char is converted (Model A), in contrast to removing the ash such that the reacting char layer is always exposed (Model B). It was found that the two modeling concepts yield significantly different mass losses and surface and center temperature predictions. Model B presents a faster thermal conversion, while the results predicted by Model A are in better agreement with what has been observed experimentally. A parametric study was also done, where the sensitivity to variations in thermal conductivity, specific surface area, and gas permeability was studied. It was found that thermal conductivity influences the time when drying and devolatilization are accomplished. This is because these conversion stages are heat-transfer-controlled. Char conversion is primarily affected by a shift to earlier times for the initialization of the final char conversion when higher thermal conductivities are used. It is found that the specific surface area smaller than a critical value can significantly affect the final char conversion time. Since char conversion is a key stage of wood combustion, the full conversion time is also affected. The gas permeability primarily affects mass diffusion into the particle. It was found that, up until a critical effective gas permeability, the modeling results are sensitive to assigned permeabilities.
Effect of the Evaluation and Mechanism Analysis of a Novel Nanohybrid Pour Point Depressant on Facilitating Flow Properties of Crude Oil Energy Fuels (IF 3.024) Pub Date : 2018-09-18 Na Li, GuoLiang Mao, Yang Liu
Microfluidic Study on the Attachment of Crude Oil Droplets to Gas Bubbles Energy Fuels (IF 3.024) Pub Date : 2018-09-17 Marcin Dudek, Gisle Øye
Gas flotation is often used during treatment of the oilfield produced water. It relies on the generation of gas bubbles and their attachment to oil drops, for example, by forming an oil film on the surface of a gas bubble. In this paper, we present a microfluidic technique for investigating the attachment of crude oil drops to gas bubbles through the spreading mechanism. The developed method allowed us to systematically study the effect of the oil, water, and gas phases, where the investigated parameter was the amount of oil droplets attached to gas bubbles through spreading. The highest attachment efficiency was observed at low or neutral pH. By reducing the salinity, the electrostatic repulsion increased, which had a negative effect on the attachment. The presence of dissolved components stabilized the oil drops and gas bubbles, which decreased their attachment through spreading. Replacing nitrogen with methane improved the attractive interactions between bubbles and oil droplets, enhancing the attachment of oil. The results confirm the potential of microfluidics in studying bubble–droplet interactions, relevant for industrial processes.
Oxidative Desulfurization of Fuels Using Heterogeneous Catalysts Based on MCM-41 Energy Fuels (IF 3.024) Pub Date : 2018-09-17 Polina Polikarpova, Argam Akopyan, Anastasia Shigapova, Aleksandr Glotov, Alexander Anisimov, Eduard Karakhanov
Experimental investigation of emission, combustion and energy performance of a novel diesel/colza oil fuel microemulsion in a direct injection diesel engine Energy Fuels (IF 3.024) Pub Date : 2018-09-17 Somaiyeh Heidari, Reza Najjar, Gaëtan Burnens, Sary Awad, Mohand Tazerout
Formulation of a novel microemulsion(ME) fuel with diesel/colza oil blend and investigation of its emission, combustion and energy performance in a diesel engine with direct injection system is reported. The new ME was prepared using diesel/colza oil (4:1) (75%), water (5%), n-butanol (10%), Brij 30(8%) and of Tween 80 (2%). This blend is an economical formulation with acceptable physical properties with high stability temperature. The results showed no significant difference between viscosity and density of new ME and diesel. The use of different surfactants in new ME formulation exerted an impressive effect on the highest stability temperature and water droplet size. All experiments were done in a diesel engine with direct injection system, run under various loads at 1500 rpm speed. The fuel efficiency measurements were performed indicating that, compared to the neat diesel fuel, ME has a higher brake specific fuel consumption (BSFC) value in all engine loads, and also higher brake thermal efficiency (BTE) value in medium engine loads. The level of emitted CO and unburned hydrocarbons were increased at full engine load. The CO2 emission value for ME and neat diesel was similar. Meanwhile, the amount of emitted NOx were decreased considerably, especially in the case of high loads of engine for ME compared with neat diesel.
Relationship between the Chemiluminescence Intensity Ratio of C2* and CH*, Charge Pressure, and Equivalence Ratio for Gasoline Energy Fuels (IF 3.024) Pub Date : 2018-09-17 Jonathan Reyes, Ranjith Kumar Abhinavam Kailasanathan, Kareem Ahmed
This work presents the results of a diagnostic system that is capable of acquiring spatial fuel-air information for a range of charge pressures and a liquid fuel. The radical intensity ratio of diatomic carbon (C2*) to methylidene (CH*) was acquired through line-of-sight chemiluminescence imaging at pressures up to 10 bar to assess the validity of the technique. Certified gasoline (99 % iso-octane, 0.9 % n-heptane, and 0.1 % other additives) and air are injected into an optically accessible pressure vessel capable of handling pressures up to 200 bar and ignited with an automotive spark plug. Line of sight images of C2* and CH* are recorded simultaneously on a single image sensor utilizing an intensifier, a high-speed camera, and various optical components to split the light signals associated with C2* and CH* (centered at 513 nm and 427nm respectively). The ratio of the signals (C2*/CH*) are acquired and compared to the measured equivalence ratio of the exhaust gases, and charge pressure. The approach allowed for characterization of the behavior of the intensity ratio at various charge pressures for a liquid fuel. The measurement demonstrates to be valid at these pressures regimes and shows promise as a diagnostic technique for automotive engines and high-pressure combustion devices.
Experimental and numerical study of the effect of CO2 on the ignition delay times of methane under different pressures and temperatures Energy Fuels (IF 3.024) Pub Date : 2018-09-17 Yang Liu, Chun Zou, Jia Cheng, Huiqiao Jia, Chuguang Zheng
Pressurized oxy-fuel combustion is regarded as a new generation of oxy-fuel technology. The ignition delay times of methane in O2/N2 atmosphere (0.21O2 + 0.79N2) and O2/CO2 atmosphere (0.21O2 + 0.79CO2) were measured in a shock tube at pressure of 0.8 atm and an equivalence of 0.5 and within a temperature range of 1501 to 1847 K. The present and Hargis’s experiment data (Hargis and Peterson, 2015) at 1.75 and 10 atm were adopted to evaluate five representative chemical kinetic models. This paper studied the chemical effects (chaperon effects of CO2 and the effects of reactions containing CO2) and physical effects of CO2 on ignition of methane at different pressures and temperatures in detail using a modified model. Artificial materials X and Y were employed to analyze the chemical and physical effects. The analysis showed that the physical effects of CO2 inhibit the ignition of methane, and are not sensitive to temperature. The chemical effects of CO2 vary greatly with pressure and temperature. At 0.8 and 1.75 atm, the chemical effects of CO2 promote the ignition of methane at high temperature, while suppress the ignition of methane at low temperature. The chaperon effects of CO2 promote the ignition of methane in O2/CO2 atmospheres at high temperature mainly because of HCO + M = CO + H + M. The chaperon effects of CO2 suppress the ignition of methane at low temperature because of the 2CH3(+M) = C2H6(+M). The chemical effects of CO2 offset the half of the physical effects of CO2 at high temperature and those two effects are great at low temperature, which is the reason for the fact that the effect of CO2 is subtle at high temperature and evident at low temperature. At 10 atm, the chemical effects of CO2 suppress the ignition of methane at 1350 – 1700 K. The chaperon effects of CO2 suppress the ignition of methane mainly due to 2CH3(+M) C2H6(+M) and are strengthened with the decrease of the temperature. The inhibition of reactions involving CO2 mainly attributes to CO + OH = CO2 + H, and weaken as the decrease of the temperature, thus, the chemical effects of CO2 on the ignition are almost not sensitive to the temperature. The effects of CO2 have almost not change with temperature at 10 atm.
Phosphorus Transformation from Municipal Sewage Sludge Incineration with Biomass: Formation of Apatite Phosphorus with High Bioavailability Energy Fuels (IF 3.024) Pub Date : 2018-09-17 Yazhou Zhao, Qiangqiang Ren, Yongjie Na
Phosphorus (P) is an essential and limited nutrient element for all life. The recovery and reuse of P from municipal sewage sludge (MSS) incineration fly ash are considered to be practical and economical. Addition of biomass into MSS was proposed to enhance the P bioavailability during incineration. The speciation conversion of P during MSS incineration with different types of biomass was studied in this work. The chemical reactions between P-containing model compound (AlPO4) and mineral model compounds in biomass (CaO and KCl) were investigated to simulate the conversion mechanism of nonapatite inorganic phosphorus (NAIP) to apatite phosphorus (AP) during MSS incineration with biomass. It is shown that the addition of biomass increases the P mass percentage and facilitates the transformation of NAIP to AP in fly ash. Cotton stalk has the most positive effect on the P transformation in the four biomass samples. Ca, Cl, K, and/or Mg compounds in biomass promote the conversion of NAIP (such as AlPO4) to AP (such as Ca2P2O7, Ca5(PO4)3Cl, and Ca10K(PO4)7) during MSS incineration. Higher temperature stimulates the transformation of NAIP to stable AP. The primary reaction pathway between phosphorus and the main components in biomass is revealed. AlPO4 can react with CaO to form Ca2P2O7 and Ca3(PO4)2 at 900 °C, and two new P-containing compounds, Ca5(PO4)3Cl and Ca10K(PO4)7, are formed in the presence of KCl.
Reaction Mechanism and Thermodynamic Properties of Aliphatic Hydrocarbon Groups during Coal Self-Heating Energy Fuels (IF 3.024) Pub Date : 2018-09-17 Xuyao Qi, Liangzhou Chen, Haihui Xin, Youcang Ji, Chengwu Bai, Runquan Song, Haibo Xue, Fangming Liu
To further understand the development of coal self-heating, the reaction sequences and thermal properties of aliphatic hydrocarbon groups during coal self-heating were analyzed. The structural parameters, frontier orbital characteristics, molecular orbital, and perturbation energy of aliphatic hydrocarbons and oxygen were analyzed by the quantum chemistry method. Then, the reaction pathways of aliphatic hydrocarbon groups and the corresponding reaction model were proposed. The results indicate that the reactions of aliphatic hydrocarbon groups include three kinds, i.e., the hydrogen capture by oxygen, reaction between aliphatic hydrocarbon radicals and the hydroxyl radical, and reaction between aliphatic hydrocarbon radicals and oxygen. The main reactions include the reaction between carbon free radicals and oxygen (E1), the reaction between aliphatic hydrocarbon and the hydroxyl radical (E2), the reaction between methyne and oxygen (E3), and other spontaneous reactions caused by E1 and E3 (E2). There is only one reaction procedure for the carbon free radical (R•) to turn into peroxide (R–O–O•) and cause more heat release. Reaction E3 generates less heat compared to reaction E1, but it can form hydroxyl radicals, which then result in other spontaneous reaction sequences (E2) to generate R•, which will easily start reaction E1. Therefore, reaction sequence E3 includes two aspects of influence during coal reaction with oxygen, i.e., heat supply and the trigger of other further reactions. It shows that the reaction sequence of aliphatic hydrocarbon groups releases more heat than other reaction sequences and plays more important roles in the temperature rise process of coal self-heating. The results are useful for further exploring the reaction mechanism of spontaneous combustion of coal.
Pore-Level Observations of an Alkali-Induced Mild O/W Emulsion Flooding for Economic Enhanced Oil Recovery Energy Fuels (IF 3.024) Pub Date : 2018-09-17 Jian Ning, Bing Wei, Runxue Mao, Yuanyuan Wang, Jing Shang, Lin Sun
The depression of the current global oil market makes the majority of chemical EOR projects worldwide nearly unprofitable, especially in China. Therefore, economic alternative methods and technologies must be quickly developed. This proof of concept research evaluates a chemical flooding method using pre-formed mild O/W emulsions, which were produced by saponification between a low-cost alkali (NaOH) and a petroleum acid-rich oil. Our focus was first given to the dynamics of the saponification with an aim to quantify alkali consumption. Afterward, the composition of the crude oil before and after the reaction was characterized using a Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR MS) to determine the preferred compounds in saponification. The physiochemical properties of the generated emulsions were further investigated through direct measurements of rheology, morphology, particle size distribution, and stability. Particular attention was placed on the oil displacement mechanisms of the emulsions at pore level. The results showed that fatty acids, naphthenic acids, and aromatic acids were clearly partitioned on the FT-ICR MS spectra of the crude oil, while the C16 and C18 fatty acids (DBE = 1, DBE represents equivalent double bond number) were predominantly saponified, which accordingly produced mild O/W emulsions (pH ≈ 7.0). The viscosity, morphology, and stability of the emulsions were found to strongly depend on the oil–water ratio. The displacement dynamics of three stable emulsions observed in a visual micromodel revealed that the O/W emulsion flooding can enlarge the sweep area and also notably reduce the residual oil saturation when employed as an EOR mode. Emulsification/entrainment, blocking, and stripping were three dominant pore level driving forces for this emulsion flooding. Phase inverse from O/W to W/O occurred when the emulsion of O/W = 3:7 was used and finally caused injectivity issue.
Study on MNO3/NO2 (M = Li, Na, and K)/MgO Composites for Intermediate-Temperature CO2 Capture Energy Fuels (IF 3.024) Pub Date : 2018-09-17 Wanlin Gao, Tuantuan Zhou, Yanshan Gao, Qiang Wang, Weiran Lin
Vegetable Oil to Biolubricants: Review on Advanced Porous Catalysts Energy Fuels (IF 3.024) Pub Date : 2018-09-14 Ahmad Masudi, Oki Muraza
Vegetable oil is one of the most potential sustainable feedstocks to produce fuels and chemicals. The review emphasizes isomerization of fatty acid as an important path for biolubricant production. The role of solid acid catalysts, including zeolites, was highlighted to design better isomerization catalysts. The isomerization is a favored mesoporous site with intermediate Brønsted acid strength, which is also enhanced after metal doping on a porous surface. The hierarchical ferrierite (FER) catalyst showed the best selective isomerization with the 10-membered ring cavities, which can be regenerated easily. FER can be produced using a low-cost organic structure-directing agent. The possibility to design two-dimensional pore zeolites with pore mouth selectivity was also discussed. Moreover, the challenges for biolubricant formulation, with focus on palm oil, were also discussed with a detailed comparison to other vegetable oils. The highest palm oil conversion was achieved over the base catalyst, namely, Sr-doped calcium oxide, with a low catalyst dosage. However, the biolubricant-based palm oil still needs many advancements to achieve industrial standards.
Lean Flammability Limits of Syngas/Air Mixtures at Elevated Temperatures and Pressures Energy Fuels (IF 3.024) Pub Date : 2018-09-14 Daniel Jaimes, Vincent G. McDonell, G. Scott Samuelsen
New experimental results for lean flammability limits (LFLs) of syngas/air (H2/CO/air) mixtures have been obtained at temperatures up to 200 °C and pressures up to 9 bar. ASTM Standard E918 (1983) provided the framework for tests at these elevated conditions, using a 1-L pressure-rated test cylinder in which the fuel–air mixtures were prepared and then ignited. The purpose for characterizing the flammability limits for these gaseous mixtures is to facilitate development of appropriate procedures for the safe industrial use of syngas, which contains large quantities of hydrogen and carbon monoxide gas. The LFLs for each gas mixture are found to decrease linearly with increasing temperature at all test pressures. The LFL results at atmospheric pressure are consistent with previous flammability studies, while those at elevated pressures represent new flammability data. An increase in the initial test pressure results in an increase of the LFLs for each test mixture, which also serves to address the lack of syngas/air flammability data at elevated pressures. An empirical formula is derived that allows for the calculation of the LFLs of all syngas/air test mixtures in the temperature and pressure range of the current study in an effort to promote the ease of use in practical applications. Predicted LFL values obtained using Le Chatelier’s mixing rule and an appropriate choice for the lower flammability limit of pure carbon monoxide are consistent with the experimentally determined values near ambient conditions of temperature and pressure.
Headspace In-Tube Microextraction and GC-ICP-MS Determination of Mercury Species in Petroleum Hydrocarbons Energy Fuels (IF 3.024) Pub Date : 2018-09-14 Zuzana Gajdosechova, Enea Pagliano, Andre Zborowski, Zoltan Mester
Chemical Kinetic Mechanism for Pyrolysis Bio-oil Surrogate Energy Fuels (IF 3.024) Pub Date : 2018-09-14 Dario Alviso, Shirley Duarte, Nelson Alvarenga, Juan Carlos Rolón, Nasser Darabiha
Bio-oil is a complex real fuel, considered as a carbon-neutral alternative to hydrocarbons in the transport sector, which is composed of hundreds of compounds, mostly oxygenated. Pyrolysis oil has high acidity, low thermal stability, low calorific value, high water content, high viscosity, and poor lubrication characteristics. Therefore, its use in transportation is limited. These characteristics make it totally different from petroleum fuels affecting the combustion process. Blends of bio-oil/diesel/alcohols are viable short-term alternatives to utilize an important fraction of these oils. In the present work, pyrolysis was performed on torrefied coconut endocarp and the collected bio-oil was analyzed using gas chromatography/mass spectrometry (GC/MS). Based on the GC/MS analysis, three different blends of toluene, ethanol, and acetic acid representative of the real fuel chemistry were proposed as the surrogates to carry out combustion studies. The objective of this paper is to develop a chemical kinetics mechanism for toluene/ethanol/acetic acid blend oxidation. This will be done by combining the chemical model of Huang et al. [ Energy Convers.Manage. 2017, 149, 553] for toluene and that of Christensen and Konnov [ Combust. Flame 2016, 170, 12] for ethanol/acetic acid reactions. The resulting chemical model consisting of 180 species and 1495 reactions will be validated by performing combustion zero- and one-dimensional simulations for toluene/ethanol/acetic acid blends by studying constant-volume autoignition and laminar flame speed. Then, as Huang et al.’s original model was developed and validated for diesel/n-butanol blends, autoignition delays and laminar flame speed simulations of bio-oil/diesel/n-butanol are presented.
Hydrogen production by steam oxidation of reduced CaFe2O4 during chemical looping coal gasification: Equilibrium and kinetic analysis Energy Fuels (IF 3.024) Pub Date : 2018-09-14 Esmail R Monazam, Ranjani V. Siriwardane
CaFe2O4 reduced with coal can be oxidized with steam to produce hydrogen. The equilibrium and conversion-time data of the oxidation of reduced CaFe2O4 with steam were analyzed over the temperature range of 1023–1123 K and steam concentrations of 10-25 vol%. Experimental data were evaluated to characterize H2 production kinetics and oxidation isotherms. The kinetics of the oxidation process followed a zero-order rate model and the film diffusion process controlled the rate. The zero-order rate constants and the parameters of film diffusion were determined based on the rate model. The steady state oxygen uptake data was also analyzed with Langmuir, Temkin, Freundlich, and Dubinin-Radushkevich isotherms. The oxidation isotherms correlated best with the Langmuir isotherm model and the maximum uptake capacity decreased with increasing temperatures, which suggests an exothermic process. The negative Gibbs free energy values indicate that oxidation process was spontaneous and favorable at 1023–1123 K.
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