• Energy Fuels (IF 3.091) Pub Date : 2018-06-21
Jacquelin E. Cobos, Peter Westh, Erik G. Søgaard

Isothermal titration calorimetry (ITC) is a technique that allows us to accurately determine the thermodynamic parameters that characterize a binding interaction between two molecular systems. However, this technique has not had a wide application in petroleum science. This study is an attempt to determine the adhesion of different fluids onto a rock surface through ITC experiments. Two artificial brines with different ionic composition were titrated into chalk powder, and then crude oil was added to those systems in order to mimic the processes that take place in an oil reservoir. In addition, the wettability alteration process associated with smart water flooding was investigated from a thermodynamic point of view. The results from the ITC experiments suggest that the interaction between smart water and chalk + brine + oil systems is both exothermic and endothermic. The exothermic heat response indicates chemisorption of sulfate (SO42–) onto the mineral lattice, whereas the endothermic response proved the substitution of carboxylate complexes from the chalk surface by magnesium (Mg2+). The ITC results also show that the performance of diluted seawater seems to be higher than smart water with increased sulfate concentration. This is due to dynamic processes like brine dilution resulting in an increased osmotic pressure.

更新日期：2018-06-22
• Energy Fuels (IF 3.091) Pub Date : 2018-06-21
Mohsen Amiri, Shahrokh Shahhosseini

The cost-effective dry regenerable K2CO3/Al2O3 seems to be a promising sorbent for CO2 removal from the flue gas of fossil fuel power plants. In this work, the characterization of the carbonation reaction and process optimization were performed in a so-called micro fluidized bed reactor (MFBR), which has recently been applied to study gas–solid reactions. The sorbent was also characterized by BET and SEM techniques. In addition, the most important gas–solid heterogeneous models were evaluated, and the kinetic parameters were determined by the model fitting approach. Based on the kinetic study results, the homogeneous model (HM) and the shrinking core model (SCM) were selected as the reaction models. Also, the effects of the independent variables including temperature, gas flow rate, and vapor pretreatment amount on the responses (adsorption capacity and reaction rate constant) were investigated by the response surface methodology (RSM) coupled with Box–Behnken design (BBD). Regarding to the analysis of variance (ANOVA) results, the temperature and gas flow rate are the most important factors affecting the adsorption capacity and the reaction rate constant, respectively. In addition, the semiempirical polynomials were developed to find the optimum condition corresponding to the highest adsorption capacity and reaction rate. Consequently, the optimum independent variables were 60 °C, 562 CCM, and 22.2 mg of H2O condition for the temperature, gas flow rate, and vapor pretreatment amount, respectively. The best response values of 65.29 mg of CO2/g of sorbent and 0.3402 (min–1) were predicted for the adsorption capacity and reaction rate constant, respectively, at the optimum conditions which were verified experimentally. The presented results are applicable and essential for future simulation and modeling CO2 capture in the fluidized bed reactor.

更新日期：2018-06-22
• Energy Fuels (IF 3.091) Pub Date : 2018-06-21
Shekhar R. Kulkarni, Laurien A. Vandewalle, Arturo Gonzalez-Quiroga, Patrice Perreault, Geraldine J. Heynderickx, Kevin M. Van Geem, Guy B. Marin

The process intensification possibilities of a gas–solid vortex reactor have been studied for biomass fast pyrolysis using a combination of experiments (particle image velocimetry) and non-reactive and reactive three-dimensional computational fluid dynamics simulations. High centrifugal forces (greater than 30g) are obtainable, which allows for much higher slip velocities (>5 m s–1) and more intense heat and mass transfer between phases, which could result in higher selectivities of, for example, bio-oil production. Additionally, the dense yet fluid nature of the bed allows for a relatively small pressure drop across the bed (∼104 Pa). For the reactive simulations, bio-oil yields of up to 70 wt % are achieved, which is higher than reported in conventional fluidized beds across the literature. Convective heat transfer coefficients between gas and solid in the range of 600–700 W m–2 K–1 are observed, significantly higher than those obtained in competitive reactor technologies. This is partly explained by reducing undesirable gas–char contact times as a result of preferred segregation of unwanted char particles toward the exhaust. Experimentally, systematic char entrainment under simultaneous biomass–char operation suggested possible process intensification and a so-called “self-cleaning” tendency of vortex reactors.

更新日期：2018-06-22
• Energy Fuels (IF 3.091) Pub Date : 2018-06-21
Valentina Gargiulo, Alicia Gomis-Berenguer, Paola Giudicianni, Conchi O. Ania, Raffaele Ragucci, Michela Alfè

The potentialities in the use of biochars prepared by steam-assisted slow pyrolysis as adsorbents of gases of strategic interest (N2, CO2, and CH4) and their mixtures were explored. The biochars prepared from Populus nigra wood and cellulose fibers exhibited a narrow microporosity, with average pore sizes ranging between 0.55 and 0.6 nm. The micropore volume increased with the pyrolysis temperature, allowing CO2 and CH4 uptakes at room temperature between 1.5 and 2.5 mmol/g and between 0.1 and 0.5 mmol/g, respectively. These values are in line with those from the literature on biomass-derived carbon-based materials, exhibiting much higher porous features than those reported herein. As for the separation of CO2/N2 and CO2/CH4 gas mixtures, data showed that the prepared biochars exhibited good selectivities for CO2 over both N2 and CH4: between ca. 34 and 119 for a CO2/N2 mixture in typical post-combustion conditions (15:85, v/v) and between 14 and 34 for a CO2/CH4 mixture typical of natural gas upgrading (30:70, v/v).

更新日期：2018-06-22
• Energy Fuels (IF 3.091) Pub Date : 2018-06-20
Rebecca L. Ware, Steven M. Rowland, Jie Lu, Ryan P. Rodgers, Alan G. Marshall

Hydrocarbon-rich pyrolysis oils produced from landfill waste and recycled plastics are potential sources for fuels and chemicals. It is well established that feedstock composition significantly affects pyrolysis oil composition and, hence, its potential uses. For example, plastics waste pyrolysis oils contain a high concentration of hydrocarbons, whereas biomass pyrolysis oils have high oxygen content. Previous studies have shown that the addition of plastics to a biomass feedstock increases the hydrocarbon content; however, a detailed analysis of hydrocarbons and polar species from pyrolysis oils produced from “real world” mixed municipal waste materials has not yet been done. Here, the silica gel fractions from unsorted landfill waste and mixed recycled plastics pyrolysis oils are analyzed by two-dimensional gas chromatography (GC × GC), field ionization mass spectrometry (FI-MS), Fourier transform infrared spectroscopy (FT-IR), and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Gravimetric results show that the plastics pyrolysis oil has a much greater concentration of saturated hydrocarbons than the more aromatic landfill pyrolysis oil. GC × GC and FI-MS for the saturated hydrocarbons show a range of alkanes, cycloalkanes, olefins, and 1-ring aromatics. Molecular elemental compositions from FT-ICR MS were correlated with structural assignments from GC × GC to expand the structural understanding of the aromatic hydrocarbons from plastics and landfill pyrolysis oils and showed that the aromatic hydrocarbons from the landfill are both peri- and cata-condensed. In contrast, plastics pyrolysis oil consists of polyphenyls and cata-condensed aromatic hydrocarbons. The polar species from the plastics pyrolysis oil contain more alcohol functionalities than the landfill pyrolysis oil, which contains non-carboxyl carbonyl functional groups. Improved structural understanding of both pyrolysis oils will provide better understanding of their properties and potential uses.

更新日期：2018-06-22
• Energy Fuels (IF 3.091) Pub Date : 2018-06-20
Ruijie Gong, Changlei Qin, Donglin He, Lili Tan, Jingyu Ran

Chemical looping with oxygen uncoupling (CLOU) represents a potentially high-efficiency approach to capture CO2 in the utilization of solid fuels. With the presence of complex mineral matters in solid fuels, the interaction between oxygen carrier and coal-derived ash in CLOU was necessary to be well understood. In this work, three typical coal ashes were selected and mixed with a Cu-based oxygen carrier (OC), and their impacts on the chemical and physical behavior of the oxygen carrier were studied comprehensively. The factor including coal ash types, ash content, CLOU cycle number, and reaction kinetics was evaluated. The results suggest that the presence of ash could lead to an obvious decrease of solid conversion during oxygen uncoupling. The most probable reason was attributed to the consumption of dissociate CuO with the formation of CuAl2O4. With the mass ratio of ash increased, the oxygen-releasing ability of samples was seen to become worse. Both of these effects tended to be a bit more serious after cyclic operation. Not only that, with the presence of ash, the reaction activation energy became higher and the reaction type changed from shrinking-core model to the nucleation and nuclei growth model.

更新日期：2018-06-22
• Energy Fuels (IF 3.091) Pub Date : 2018-06-20
Kai Zhang, Yucui Hou, Yiming Wang, Kun Wang, Shuhang Ren, Weize Wu

Extremely low-volatility functional deep eutectic solvents (DESs), based on ethylene glycol (EG) and diethylene glycol (DG) as hydrogen-bond donor and the ammonium salts obtained from triethylenetetramine (TETA) and HCl at different mole ratios as hydrogen-bond acceptor, were designed and used to capture CO2. All of the designed DESs can efficiently capture CO2 even at low partial pressures. CO2 absorption capacity of [TETA]Cl-EG DES with n[TETA]Cl/nEG 1:3 is high up to 17.5 wt % (1.456 mol CO2/mol [TETA]Cl) at 40 °C and 1 atm. CO2 absorption capacity decreases with increasing temperature and decreasing CO2 partial pressure. Regeneration experiments show that CO2 absorption capacities in [TETA]Cl-EG DES and [TETA]Cl-DG DES do not vary after five absorption/desorption cycles. It is found that EG or DG can increase the absorption capacity via activating −NH– or −NH2 on [TETA]Cl and enhance the basicity of DESs. In addition, CO2 absorption mechanism in [TETA]Cl-EG DES based on the change of its viscosity during absorption and FTIR analysis indicates that there is a chemical interaction between CO2 and [TETA]Cl, and the stoichiometry for the reversible absorption is 1.5 molecules of CO2 per [TETA]Cl-EG DES molecule.

更新日期：2018-06-22
• Energy Fuels (IF 3.091) Pub Date : 2018-06-21
Kale W Harrison, Kyle E Rosenkoetter, Benjamin Grant Harvey

Alkyl diamondoid fuel mixtures have been prepared under moderate conditions by AlBr3 catalyzed cracking of nonane and heptane in the presence of adamantane. The fuel mixture prepared with heptane as the alkyl source (HA) contains primarily 1-ethyl-3-methyl adamantane and 1-propyladamantane, while the mixture prepared from nonane (NA) contains primarily C13-C15 alkyl diamondoids. Both fuel mixtures exhibit densities greater than 0.9 g/mL and volumetric net heats of combustion approximately 10 and 6 % higher than conventional jet and diesel fuels, respectively. The structural diversity of the fuel blends and presence of multiple branch sites lead to lower viscosities compared to pure alkyl diamondoid fuels. The lower molecular weight blend, HA, exhibits a 40 °C kinematic viscosity of 3.22 mm2s-1, well within the specification for diesel fuel, and both blends have derived cetane numbers > 42, suggesting that they can be used directly in conventional diesel engines.

更新日期：2018-06-22
• Energy Fuels (IF 3.091) Pub Date : 2018-06-21
Qingxiang Wang, Zhichao Chen, Tao Liu, Lingyan Zeng, Xin Zhang, He Du, Zhengqi Li

A new deep-air-staging and low-NOx technology has been introduced to a 300 MWe anthracite- and down-fired boiler with swirl burners. Industrial experiments were performed at different outer secondary air vane angles (defined as β) (i.e., 20, 30, 40, and 50°) to evaluate the environmental and economic performance for the retrofitted boiler. Furthermore, combining with the previous investigations on the inner secondary air vane angle (defined as α), the influence degree of β and α on anthracite combustion and NOx emissions for the retrofitted boiler were further analyzed and compared. The experimental results revealed that, the main factors affecting the ignition and the flame fullness for the β and α are different. Compared with the α, the β had a relatively greater influence on NOx emissions for the retrofitted boiler. Compared with the orignianl boiler, a strong reducing atmosphere was formed in the primary combustion zone for the retrofitted boiler, and for the β of approximately 30°, the arithmetic mean of NOx emissions in the whole measurement range was reduced by 1073 mg/m3 at 6% O2. Taking consideration of environmental and economic effects, the optimal β for the retrofitted boiler was 20°.

更新日期：2018-06-22
• Energy Fuels (IF 3.091) Pub Date : 2018-06-21
Xiangchun Chang, Honggang Zhao, Wenxiang He, Xu Yaohui, Youde Xu, Yue Wang

Biodegraded oils have been widely discovered throughout the world, whereas the alteration of the molecular composition of oils at extreme levels (>PM8) has been insufficiently documented. A suite of crude oils from Carboniferous volcanic reservoirs in the eastern Chepaizi Uplift, Junggar Basin, experienced severe to extreme biodegradation (PM6+ to PM9+), which provided an ideal case for the present study. This investigation showed that the variations in molecular composition were not strictly consistent with their stepwise fashion in established schemes. The idea that the 25-norhopanes are derived from hopanes was confirmed by the sharp decreases in the C29 hopane/gammacerane (C29H/G) and C30 hopane/gammacerane (C30H/G) values at the level of extreme biodegradation, which were associated with the increases in their counterparts of C28 25-norhopane/gammacerane (C28 25-NH/G) and C29 25-norhopane/gammacerane (C29 25-NH/G). 25-norhopanes were also biodegraded at an extreme level, with C29 25-NH being more susceptible than C28 25-NH. The preferential biodegradation of individual homohopanes by carbon number occurred at an extreme level, whereas C29H featured more bio-resistance than C30H and shared a similar susceptibility to biodegradation as 18α-30-norneohopane (C29Ts). The formation of 22R isomers for 25- norhopanes seemed to be favored over that of 22S isomers, although the 22S isomer was degraded faster that the 22R epimer for the C31, C32 and C33 homohopanes. However, the constant values of 22S/(22S+22R) for the C34 homohopane implied no preferential biodegradation of 22S or 22R isomers for this extended hopane. Lower- molecular- weight tricyclic terpanes (TT) were preferentially removed at extreme biodegradation levels, and the late-eluting stereoisomers were degraded faster than the early-eluting ones for C26TT, C28TT and C29TT. C24 tetracyclic terpane (C24Tet) is much more resistant to biodegradation than TTs. Pregnanes have a similar susceptibility to biodegradation as gammacerane, but they are more resistant than C23TT. The biodegradation of regular steranes was characterized by their faster depletion than diasteranes and the preferential depletion of C27 regular sterane to the C29 homolog and the 20R isomers to the 20S isomers. At the extreme level, even C20 and C21 triaromatic steroids (TAS) were distinctively reduced, coexisting with the relatively highly degraded steranes and terpanes, although water washing can also be responsible for the decreases in (C20+C21)- TAS/C26-28-TAS values.

更新日期：2018-06-22
• Energy Fuels (IF 3.091) Pub Date : 2018-06-20
Marco Lubrano Lavadera, Yu Song, Pino Sabia, Olivier Herbinet, Matteo Pelucchi, Alessandro Stagni, Tiziano Faravelli, Frédérique Battin-Leclerc, Mara de Joannon

The influence of the main process parameters on the oscillatory behavior of methane oxidation was analyzed in conditions relevant for Low Temperature Combustion (LTC) processes. The investigation was performed by means of direct comparisons between experimental measurements realized in two Jet Stirred Flow Reactors used at atmospheric pressure. Coupling the operating conditions of the two systems, wide ranges of inlet temperature (790 - 1225 K), equivalence ratio (0.5 < Φ < 1.5), methane mole fraction (XCH4 from 0.01 to 0.05), bath gases (i.e. He, N2, CO2, or H2O) as well different overall mixture dilution levels, were exploited in relation to the identification of oscillatory regimes. Although the reference systems mainly differ in thermal conditions (i.e. heat exchange to the surroundings), temperature measurements suggested that the oscillatory phenomena occurred when systems working temperature accessed a well-identifiable temperature range. Experimental results were simulated by means of a detailed kinetic scheme and commercial codes developed for complex chemistry processes. Simulations were also extended considering systems with different heat loss to the surroundings, thus passing from adiabatic to isothermal systems. Results highlighted the kinetic nature of the dynamic behavior. Because of predictions were consistent with experimental tests, further numerical analyses were realized to identify the kinetics responsible for the establishment of oscillatory phenomena. Temperature oscillations were predicted for a significant reactor working temperature range, where oxidation and recombination kinetic routes, involving carbon C1-2 species as well as reactions of the H2/O2 sub-scheme, become competitive, thus boosting limit cycles behaviors. Oscillatory phenomena end up when system working temperatures exceed characteristic threshold values with the promotion of faster oxidation routes that diminish the inhibiting effects of recombination reactions.

更新日期：2018-06-22
• Energy Fuels (IF 3.091) Pub Date : 2018-06-20
Jie Yang, Liping Ma, Dalong Zheng, Siqi Zhao, Yuhui Peng

In this study, syngas preparation by chemical looping gasification (CLG) process is investigated through theory and experiment. The starting materials for the syngas are low quality lignite, which cannot be used for other applications, and phosphogypsum (PG), which is a by-product of wet phosphoric acid production. The results show that the CO production is mainly due to the following reaction: <> and , while the main reactions of H2 generation are: <> and <>. The analysis results indicate that high temperature and water vapor content are detrimental for phosphogypsum recycling. Furthermore, after three times recycling of phosphogypsum, some sintering is observed. The composition of syngas is very important for the corresponding applications. Therefore, the relationships between reaction factors and products are also investigated. The results of Analysis of Variance (ANOVA) show that H2 and CH4 generation are strongly dependent on water vapor content. The influence of the different factors on CO yield is in the following order: molar ratio of PG/lignite > temperature > water vapor. Among the three factors, the effect of reaction temperature on CO2 generation is less than that of the other factors. Moreover, the reaction temperature and the molar ratio of PG/lignite have a great influence on lignite decomposition. The results of this work can provide some guidance for preparing syngas with the desired composition by the CLG process.

更新日期：2018-06-22
• Energy Fuels (IF 3.091) Pub Date : 2018-06-20
Antonio Galgano, Colomba Di Blasi, Roberto De Vita

An unsteady one-dimensional model for the solid phase is applied to simulate the spontaneous ignition and burning of thick wood samples with grain orientation parallel or perpendicular to incident heat fluxes in the range 18-40kW/m2, that is, in the absence of flame. The description of heat and mass transfer processes, at constant gas pressure, is combined with global volumetric rates of wood decomposition and char oxidation. Surface regression occurs for a limit value of char density while a critical surface temperature describes ignition. Good quantitative predictions are obtained for the ignition times and the surface temperature and mass loss rate profiles during burning. Conversion always consists of three main stages. The first short transients correspond to the formation of a relatively thin charred surface layer and glowing ignition. The second much longer stage represents a pseudo-steady state burning, where the rates of advancement of the decomposition and oxidation zones are approximately constant as well as the surface temperature and the global rate of mass loss. Finally, the last short stage, resulting from the adiabatic bottom condition, is the enlargement of the decomposition zone to the entire sample. The first transient stage and the ignition times are noticeably affected by the external heating conditions whereas the characteristics of the pseudo-steady burning are mainly dependent on the char oxidation rate which is controlled by the oxygen diffusion rate.

更新日期：2018-06-22
• Energy Fuels (IF 3.091) Pub Date : 2018-06-19
M. Sadeckas, N. Striu̅gas, P. Andriu̅nas, R. Navakas, M. Praspaliauskas, M. Rabaçal, M. Costa

Spontaneous emission intensities of Na*, Ca*, and K* during the combustion of single wood and straw pellets doped with known concentrations of Na, Ca, and K were measured using optical bandpass filters mounted on an intensified charge-coupled device camera. The impregnated biomass pellets were suspended in a natural gas flat flame at 750 and 1000 °C. Before the pellets were made, the biomass samples were washed and soaked to demineralize and doped with different concentrations of Na, Ca, and K (0.5, 2, and 5 wt %). During the experiments, the temperature at the center of the pellets was measured with a thermocouple and the combustion stages were identified with the help of the temperature derivative. The results reveal that, at the lower gas temperature, the emission of the selected alkalis is marginal, in agreement with previous studies. At the higher gas temperature, the emission profiles reveal that K and Na are released distinctively in the volatile combustion and char combustion stages. The presence of large amounts of silica and alumina may trap the alkalis in the solid phase, leading to a reduced emission of these species during the char combustion. Calcium does not evaporate at the tested temperature conditions, but the temperature is high enough to promote the decomposition of calcium oxalate in the outer layer of the pellet, leading to a flat emission profile during the combustion stages. Finally, the total integrated emission increased proportionally with the increase of the doping concentration for all species.

更新日期：2018-06-20
• Energy Fuels (IF 3.091) Pub Date : 2018-06-19
Da Wang, Yuyang Wang, Xiaoyu Li, Lei Chen, Guangci Li, Xuebing Li

In situ catalytic hydrogenolysis of lignin is an efficient method for lignin valorization. Herein, a novel in situ lignin catalytic hydrogenolysis technique in alkaline aqueous solution over a NiAl alloy catalyst under mild conditions was systematically suited. Ni served as the active phase and could be exposed by etching Al atoms with alkaline aqueous solution. Meanwhile, H2 resources could be in situ generated and easily arrived at the adjacent exposed Ni sites to be activated. The in situ lignin hydrogenolysis system exhibits attractive depolymerization results under mild conditions, with an 86.8% conversion degree and 18.9 wt % yield of aromatic monomers at 220 °C, much higher than the traditional hydrogenolysis method using a commercial Raney Ni catalyst under high pressure external H2. The mechanism studies with lignin model compounds suggest that alkaline aqueous solution could promote the cleavage of C–O–C bonds and hinder the hydrogenation of the benzene ring. In addition, a moderate amount of exposed Ni sites as well as rich active hydrogen species are determinant for efficient lignin depolymerization.

更新日期：2018-06-20
• Energy Fuels (IF 3.091) Pub Date : 2018-06-19
René B. Madsen, Konstantinos Anastasakis, Patrick Biller, Marianne Glasius

This paper investigates the use of Fourier transform infrared spectroscopy (FT-IR) for quantitative analysis of bio-crudes from hydrothermal liquefaction (HTL) of biomass. HTL is a versatile process rendering virtually all biomasses suitable for conversion into bio-crude and side-streams. However, continuous processes require rapid analytical methods applicable to highly diverse bio-crudes. Bio-crudes were obtained from two different continuous HTL reactors (lab scale and pilot scale) and in some cases with recirculation of water. The bio-crudes originated from a diverse range of feedstocks including lignocellulosics (pine, Miscanthus), microalgae (Spirulina, Chlorella vulgaris), and residues (sludge, dried distiller grains with solubles). Quantitative analysis of water content, total acid number, and total content of phenolics was performed using FT-IR. Principal component analysis indicated a potential correlation between quantitative measurements and FT-IR. Partial least-squares regression was used to develop predictive models that performed well considering the high diversity of the bio-crudes. The content of phenolics was in the range of 83.1–254.6 mg g–1 (gallic acid equivalent), and the model calibration was good (Root Mean Square Error, RMSE = 19.7, slope = 0.81, y-exp = 81.2%). A diverse set of test samples were subjected to the models. The relative difference for measured and predicted phenolic content was generally <15%. Total acid numbers (TAN) were 7–98 mgKOH g–1, and the model calibration was found to be satisfactory considering the titration method used (RMSE = 18.5, slope = 0.53, y-exp = 52.6%). The relative difference for measured and predicted TAN was generally <20%. The water content (Karl Fischer titration) was 1–24%, and the model calibration was very good (RMSE = 2.0, slope = 0.93, y-exp = 92.6%). The water content was generally predicted within 1.5%, and the relative difference for measured and predicted water content was large (2.7–16.6%) due to the small values. All models included samples that deviated and could be considered outliers; however, their deviations were explained from their composition and were retained in the models. Overall, the results show the potential of FT-IR as a universal technique to obtain rapid quantitative results from a variety of bio-crudes processed using different reactors.

更新日期：2018-06-20
• Energy Fuels (IF 3.091) Pub Date : 2018-06-19
Haifeng Zhou, Roland Gleisner, J.Y. Zhu, Yuanyu Tian, Yingyun Qiao

This study conducted an investigation of the recycle utilization of SPORL pretreatment spent liquor. Three lignosulfonates (LSs) were purified from the spent liquor of SPORL pretreated Beetle-killed lodgepole pine (BKLP), Poplar NE222 (NE222) and Douglas-fir (FS10). The structural characterization showed that the apparent molecular mass and sulfur content of NE222-LS was lowest, but the phenolic group content of which was highest. FS10-LS, from a pH profiling SPORL pretreatment, had the highest apparent molecular mass, but medium sulfur and phenolic group content. The spectra analyses exhibited that guaiacyl unit was the main structure in BKLP and FS10 LSs, while NE222-LS mainly contained both guaiacyl and syringyl units. Both LSs and SPORL pretreatment spent liquors were used as additives to enzymatic hydrolysis of Whatman paper and ethanol production from glucose. LSs and liquors, from SPORL pretreated BKLP and NE222, could enhance the enzymatic saccharification obviously. Nevertheless, LS and liquor from SPORL pretreated FS10 presented a slight negative effect on enzymatic saccharification. All LSs and liquors with low concentration exhibited no inhibition on ethanol fermentation from glucose. When whole spent liquors without any detoxification were applied to prepare the fermentation medium with initial glucose concentration of 100 g/L, the ethanol yield was almost the same with control for BKLP and FS10 liquors. Nevertheless, the whole NE222-liquor without detoxification inhibited ethanol production thoroughly.

更新日期：2018-06-20
• Energy Fuels (IF 3.091) Pub Date : 2018-06-19
Wu Piao, Dujie Hou, Jun Gan, Xing Li, Wenjing Ding, Gang Liang, Bibo Wu

Few research regarding the organic geochemistry of source rock deposited in marine or transitional environment in the eastern deep-water area of Qiongdongnan Basin (QDNB) has been performed so far. Basing upon the organic geochemical and petrological data of mudstone samples collected from the eastern deep-water area in the QDNB, combined with palynological data of rock samples in the shallow-water area, this paper studies the paleoenvironment, hydrocarbon potential, and controlling factors of Oligocene source rock in different sedimentary facies in the eastern QDNB. Two distinct models of delta front source rock and neritic source rock are proposed according to organic matter sources and geochemical characteristics. Source rock in delta front subface is of medium to high organic abundance and gas-prone type kerogen, the geochemical biomarkers are characterized by high ratios of pristane/phytane, oleanane/C30 hopane, T-bicadinane/C30 hopane, and low ratios of C23 tricyclic terpane/C30 hopane, C27 sterane/C29 sterane, (nC21+nC22)/(nC28+nC29). However, source rock in neritic face has medium organic richness and kerogen type prone to generate both oil and gas, the biomarkers are characterized by low ratios of pristane/phytane, oleanane/C30 hopane, T-bicadinane/C30 hopane, and high ratios of C23 tricyclic terpane/C30 hopane, C27 sterane/C29 sterane, (nC21+nC22)/(nC28+nC29). During the Oligocene epoch, the paleoclimate in the QDNB was subtropical warm-humid, and paleovegetation around and within the sags was dominated by pteridophyte and angiosperm plants, causing terrestrial higher plants to be the main organic matter source. Source rock in delta front subface is formed in oxidation fresh or brackish water environment, whereas source rock in the neritic face is formed in weak oxidization brackish or saline water condition. Organic matter abundance in the delta front subface is mainly controlled by the terrigenous organic matter input, whereas organic matter abundance in the neritic face is controlled by aquatic organic matter input and influenced by the water redox environment.

更新日期：2018-06-20
• Energy Fuels (IF 3.091) Pub Date : 2018-06-19
Bailin Xiang, Qingxia Liu, Jun Long

The detachment of bitumen from sand grains in oil sands processing is known as bitumen liberation. In this study, a quartz crystal microbalance with dissipation (QCM-D) was applied to study the bitumen liberation process under various process conditions. Bitumen was coated on the surface of silica sensors to simulate the oil sands ore. By recording the change of frequency and dissipation of the coated sensor, QCM-D allows a real time quantitative analysis of bitumen detachment process. The effects of solid wettability, solution pH, and operation temperature on bitumen liberation were investigated using QCM-D. The effects of different solution pH and temperatures on bitumen liberation were conducted with untreated hydrophilic silica sensors. It was found that the degree of bitumen liberation (DBL) was improved from approximate 32% to 98% when the solution pH was increased from 7.8 to 11, indicating the importance of solution pH in water based bitumen extraction process. Increasing temperature enhanced not only the degree of bitumen liberation, but also the rate of bitumen detachment. The DBL from a hydrophobic silica surface was about 1.2% at pH 11.5 and 22C, which is much lower than the hydrophilic one. QCM-D is a powerful tool in studying the bitumen liberation from hydrophobic and hydrophilic surfaces.

更新日期：2018-06-20
• Energy Fuels (IF 3.091) Pub Date : 2018-06-19
Shane Daly, Kyle Evan Niemeyer, William J. Cannella, Christopher L. Hagen

Design and optimization of higher efficiency, lower-emission internal combustion engines are highly dependent on fuel chemistry. Resolving chemistry for complex fuels, like gasoline, is challenging. A solution is to study a fuel surrogate: a blend of a small number of well-characterized hydrocarbons to represent real fuels by emulating their thermophysical and chemical kinetics properties. In the current study, an existing gasoline surrogate formulation algorithm is further enhanced by incorporating novel chemometric models. These models use infrared spectra of hydrocarbon fuels to predict octane numbers, and are valid for a wide array of neat hydrocarbons and mixtures of such. This work leverages 14 hydrocarbon species to form tailored surrogate palettes for the Fuels for Advanced Combustion Engine (FACE) gasolines, including candidate component species not previously considered: \textit{n}-pentane, 2-methylpentane, 1-pentene, cyclohexane, and \textit{o}-xylene. We evaluate the performance of full'' and reduced'' surrogates for the 10 fuels for advanced combustion engine (FACE) gasolines, containing between 8--12 and 4--7 components, respectively. These surrogates match the target properties of the real fuels, on average, within 5%. This close agreement demonstrates that the algorithm can design surrogates matching the wide array of target properties: octane numbers, density, hydrogen-to-carbon ratio, distillation characteristics, and proportions of carbon--carbon bond types. We also compare our surrogates to those available in literature (FACE gasolines A, C, F, G, I and J). Our surrogates for these fuels, on average, better-match RON, MON, and distillation characteristics within 0.5%, 0.7%, and 0.9%, respectively, with literature surrogates at 1.2%, 1.1%, and 1.8% error. However, our surrogates perform slightly worse for density, hydrogen-to-carbon ratio, and carbon--carbon bond types at errors of 3.3%, 6.8%, and 2.2% with literature surrogates at 1.3%, 2.3%, and 1.9%. Overall, the approach demonstrated here offers a promising method to better design surrogates for gasoline-like fuels with a wide array of properties.

更新日期：2018-06-20
• Energy Fuels (IF 3.091) Pub Date : 2018-06-19
Liang Wang, Ning Zhao, Liqiang Sima, Fan Meng, Yuhao Guo

Pore structure is the most important factor affecting reservoir quality and petrophysical property of tight reservoir. The effective characterization of pore structures, including pore radius distribution (PRD), throat radius distribution (TRD), pore-throat radius distribution (PTRD), relevant pore structure parameters, etc., is of great importance for the oil exploration and exploitation. Taking the tight sandy conglomerate reservoir as research target of tight reservoir, this paper characterizes the pore structures by a combination of experiments on parallel core samples. These experiments include high-pressure mercury injection (HPMI), constant-rate mercury injection (CRMI), nuclear magnetic resonance (NMR), as well as microscopic analysis of casting thin sections (CTS) and scanning electron microscopy (SEM). This paper systematically analyzes the advantages and shortcomings of these commonly used experimental techniques. And then, novel methods are proposed to characterize the pore structure (especially the full-range PRD, TRD, and PTRD) by utilizing the advantages of these techniques. In addition, an advanced pore classification scheme is proposed to reclassify the pore types. Finally, the controls of the pore structure on the flow characteristics are investigated, which in turn further demonstrates the correctness and importance of the proposed novel methods for characterizing pore structures. In summary, this study proposes novel methods to characterize the pore structure by integration of HPMI, CRMI, and NMR, and provides insights into the pore structure characteristics of the tight sandy conglomerate reservoir.

更新日期：2018-06-20
• Energy Fuels (IF 3.091) Pub Date : 2018-06-19
Guanwen Lu, Chongtao Wei, Jilin Wang, Gaoyuan Yan, junjian zhang, Yu Song

Based on methane isothermal adsorption experiments, the supercritical methane adsorption characteristics of middle rank tectonically deformed coals (TDCs) screened from the Huaibei coalfield were analyzed. The applicability of different adsorption models to different kinds of TDCs is discussed using standard deviation method, and the mechanism of methane adsorption in TDCs was explored. The following results were obtained. First, the experimental maximum adsorption capacity of TDCs increases gradually with enhanced tectonically deformation, and the experimental maximum adsorption capacity of ductile TDCs is significantly higher than those of primary coal and brittle TDCs. The adsorption potential of TDCs gradually decreases with increasing adsorption space, and the adsorption potential of ductile TDCs is generally higher than those of primary coal and brittle TDCs. Second, for the applicability of adsorption models to TDCs, the highly applicable models of primary, cataclastic and scaly coals are the Toth, Langmuir-Freundlich, and Dubinin-Astakhov models; the highly applicable models of schistose coals are the Langmuir, Toth, Langmuir-Freundlich, Three-parameter-Brunauer Emmett Teller, Dubinin-Radushkevich and Dubinin-Astakhov models; the highly applicable models of wrinkle coals are the Toth, Langmuir-Freundlich, Dubinin-Radushkevich and Dubinin-Astakhov models; and the highly applicable models of mylonitic coals are the Langmuir, Toth, Langmuir-Freundlich, Expand-Langmuir, Three-parameter-Brunauer Emmett Teller and Dubinin-Astakhov models. Thirdly, the Three-parameter-Brunauer Emmett Teller model is suitable to study the adsorption state of TDCs. As the deformation degree increases, the adsorption state of TDCs transforms from monolayer unsaturated adsorption to multilayer adsorption. TDCs have larger adsorption potential and adsorption space with the enhancement of tectonically deformation, which increases the number of adsorption layers on the coal surface.

更新日期：2018-06-20
• Energy Fuels (IF 3.091) Pub Date : 2018-06-19
Chengdong Yuan, Dmitrii A Emelianov, Mikhail A. Varfolomeev, Wan-Fen Pu, Alexandra S Ushakova

In this study, the oxidation behavior and kinetics of linear alkanes (C20H42, C24H50, C30H62, C32H66, C36H74, C38H78, C50H102, and C54H110) were investigated by high pressure differential scanning calorimetry (HP-DSC). It turned out that only the exothermic peak of low-temperature oxidation (LTO) was observed during the oxidation process of these linear alkanes, which is different from the oxidation behavior of the crude oil. For the crude oil, two exothermic peaks were observed: LTO and high-temperature oxidation (HTO). It means that the linear alkanes barely contributed in the HTO reaction of crude oils. In addition, the exothermic peaks in the oxidation process of all these linear alkanes were overlapped each other. They showed almost the same oxidation behavior in terms of the temperature range of reaction as well as the onset and peak temperatures. It seems that the oxidation behavior of the tested linear alkanes was independent of their carbon number. It was also found that increasing pressure resulted in an increase of the heat release. The kinetics parameters of the oxidation reaction were estimated using three “model-free methods” known as Friedman, Ozawa-Flynn-Wall (OFW), and ASTM E698. The results showed that the activation energy of the LTO process of each linear alkane can be regarded as a constant average value in the range of conversion degree from 0.2 to 0.8, and all the tested linear alkanes had the similar activation energy values of 80 – 120 kJ/mol calculated by Friedman method and 90 – 110 kJ/mol calculated by OFW method. OFW method showed a lower error than Friedman method when being applied to the DSC data. The values of activation energy estimated using ASTM E698 method were 100.41, 95.61, 93.62, 100.55, and 92.47 90 – 110 kJ/mol for C20H42, C24H50, C30H62, C38H78, and C54H110, respectively, which are also in the same range of the values of the activation energy obtained by Friedman and OFW methods. Similar activation energy values of different linear alkanes partly explained why they showed almost the same oxidation behavior.

更新日期：2018-06-20
• Energy Fuels (IF 3.091) Pub Date : 2018-06-19
Chong Dai, Bo Wang, Ziyun Shu, Jianchun Mi

This study investigates the diluent-dependent diffusion flames of an axisymmetric methane jet in annular hot coflow (JHC) of oxidizer diluted by ‘inert’ N2, CO2 and H2O, respectively. The fuel jet issues at the exit Reynolds number  10,000 while the hot (1300K) coflow oxygen level (molar fraction) varies between 6% and 23%. To identify the chemical and physical factors, simulations of the diffusion flames diluted by fictitious gases XH2O and XCO2 are also conducted. Inspections and analyses to combustion radicals and heat-release-rates are made on the stoichiometric sheet. Results show that the stoichiometric length, temperature and volumetric heat-release-rate vary drastically with coflow oxygen level or dilution extent. The flame volume increases greatly when replacing the diluent N2 with CO2 but reduces substantially under the H2O dilution. Such discrepancies are found to stem mainly from specific physical properties of N2, CO2 and H2O. The CO2 and H2O dilutions show more chemical impact on the formations of key intermediate species. Besides, the dilution by CO2 weakens all the main reactions, thus producing the mildest flame, whereas that by H2O promotes the formations of radicals OH and H2, enhancing the heat-release-rate. At last, the global heat contributions of C-included and C-excluded (H2-O2) reactions are examined so as to understand the roles of the H2-O2 kinetics in the oxy-combustion.

更新日期：2018-06-20
• Energy Fuels (IF 3.091) Pub Date : 2018-06-19
Jamie Whelan, Marios S Katsiotis, Samuel Stephen, Gisha Elizabeth Luckachan, Anjana Tharalekshmy, Nicoleta-Doriana Banu, Juan-Carlos Idrobo, Sokrates T. Pantelides, Radu Valentin Vladea, Ionut BANU, Saeed M. Alhassan

Hydrodesulfurization (HDS) of crude oil plays a vital role in the refining of petroleum products. With ever-increasing regulations restricting the allowable concentrations of sulfur in fuel, further research is required to produce more efficient and effective catalysts. Herein we have synthesized carbon-nanotube (CNT)-supported cobalt-molybdenum (CoMo) catalysts for HDS of dibenzothiophene (DBT) via Co-first and Mo-first sequential impregnation as well as co-impregnation. Spectroscopic analysis shows the formation of a CoMo catalyst with no free sulfided Co phase present. Additionally, CoMo catalysts are found to be predominantly single-layered nanocatalysts layered on the CNT support. Temperature programmed reduction (TPR) measurements show differences in reducing temperature of the sulfided CoMo catalysts prepared by the different methods but catalyst activities for HDS of DBT did not fully align with the TPR-predicted order. Thus, provided the reaction temperature is high enough, reducibility may not always be an adequate gauge of catalytic activity. Conversion of DBT was highest in Mo-first sequential impregnation (81.5%), followed by co-impregnation (64%) and Co-first sequential impregnation (60%) on CNT support. While these results contrast with others regarding the order of impregnation, we propose that the preferred impregnation order is actually support-dependent, rather than an absolute quality.

更新日期：2018-06-20
• Energy Fuels (IF 3.091) Pub Date : 2018-06-18
Shweta Narayan, Davis B. Moravec, Brad G. Hauser, Andrew J. Dallas, Cari S. Dutcher
更新日期：2018-06-18
• Energy Fuels (IF 3.091) Pub Date : 2018-06-18
Xinyan Pei, Lingyun Hou, William L. Roberts

In the fuel cooling system of an engine, the heating of aviation kerosene causes it to exhibit complicated, unsteady physicochemical processes and forms undesirable coke deposition. To understand these processes better, we investigated the coupling relationship between turbulent flow, heat transfer, autoxidation, and deposition reactions of fuel in a cooling heat exchanger. The experiments were performed to investigate the whole process within 105 min, separated into five continuous phases of 20, 40, 60, 80, and 105 min, with a heat flux of 38.6 kW/m2. On the basis of the experimental results, we established a three-dimensional model to study the influence of kerosene’s heat-transfer process on oxidation deposition in a long, straight, horizontal pipe under supercritical pressure condition. A modified six-step, pseudo-detailed chemical kinetic and global deposition mechanism has been incorporated into the numerical model with particular attention to temperature variation. The model was validated based on the quantity of deposition and dissolved oxygen consumption rate under different experimental temperatures and heating times. We then analyzed the fluid dynamics profiles and physical parameters of density, specific heat, viscosity, and Reynolds number, species, and deposition rates along the reactor, micrographs, and surface elements of deposition at various temperatures to understand the coupling effect between heat transfer and coke deposition. The results indicated that supercritical characteristics of both the fuel and deposition affect the local heat-transfer characteristics, resulting in some instabilities in the wall temperature distribution. The fuel temperature determines the regime of the chemical reactions in the flow, and the flow conditions and wall temperature determine the deposition rate at the local position of the inner surface.

更新日期：2018-06-18
• Energy Fuels (IF 3.091) Pub Date : 2018-06-18
Kamilla Fellah, Shin Utsuzawa, Yi-Qiao Song, Ravinath Kausik

Petrophysical measurements of drill cuttings are vital for determining reservoir quality in organic mudstone plays, where the highly deviated (horizontal/lateral) production wells are rarely logged. We demonstrate a methodology to measure the porosity of irregularly shaped drill-cutting samples using multinuclear 1H–19F NMR measurements at medium frequencies (12 MHz). The methodology is successfully demonstrated on both core and irregularly shaped simulated cuttings from conventional and unconventional shale plays.

更新日期：2018-06-18
• Energy Fuels (IF 3.091) Pub Date : 2018-06-18
Zhi Xu Chen, Nguyen Anh Khoa Doan, Xiao Jing Lv, Nedunchezhian Swaminathan, Giuseppe Ceriello, Giancarlo Sorrentino, Antonio CAVALIERE

A cyclonic burner operating under moderate or intense low-oxygen dilution (MILD) conditions is simulated using a Perfectly Stirred Reactor (PSR) incorporated within a tabulated chemistry approach. A presumed joint probability density function (PDF) method is utilised with appropriate sub-models for the turbulence-chemistry interaction. Non-adiabatic effects are included in the PSR calculation to take into account the effects of non-negligible wall heat loss in the burner. {\color{black}Five different operating conditions are investigated and the computed mean temperatures agree well with measurements. A substantial improvement is observed when the non-adiabatic PSR is used highlighting the importance of heat transfer effects for burner configurations involving internal exhaust gas recirculation (EGR). Furthermore, enhanced reaction homogeneity is observed in this cyclonic configuration for the globally lean case, leading to a more spatially uniform temperature variation with MILD combustion.

更新日期：2018-06-18
• Energy Fuels (IF 3.091) Pub Date : 2018-06-18
Seyedeh Hosna Talebian, Muhammad sagir, Mudasser Mumtaz

Foam is used in CO2-EOR due to its potential high benefits in mitigating all three causes of CO2 poor sweep efficiency, as it provides a means to lower the effect of permeability heterogeneity, overcome viscous instability, and minimize the occurrence of gravity override. The conventional foaming surfactants are not suitable in contact with oil due to premature lamellae rupture, need of copious amount of water to generate foam, surfactant loss due to adsorption on the rock or partitioning between water and oil, and less tolerance against salinity, pressure and temperature. The surfactant blending and addition of CO2-philic functionalities in surfactant structure is suggested to mitigate the above problems, enhance foam stability, improve mobility control, and accelerate foam propagation. However, there is a lack of general guideline on the evaluation of CO2-philic surfactant properties and applications and the surfactant structure-performance analysis. An integrated methodology consisting of tailored laboratory tests and simulation analysis was conducted on CO2-philic surfactants with different structure and chain lengths in conditions close to a Malaysian reservoir case and in the presence of oil. The results from experiments combined with analytical analysis of foam flow parameters are used to provide comprehensive simulation model of CO2-philic surfactant alternating gas process. A meaningful correlation between the CO2-philic surfactant structure and the sensitivity of foam model to different parameters was observed. The model sensitivity analysis also defines that optimization of CO2-philic surfactant activity at gas-water (foam stability) and oil-water interfaces, can improve the system recovery through macroscopic and microscopic displacement.

更新日期：2018-06-18
• Energy Fuels (IF 3.091) Pub Date : 2018-06-18
shujun zhu, Qinggang Lyu, Jianguo Zhu, Huixing Wu, Guanglong Wu

This study reports an experimental investigation on the nitrogen oxides (NOx) emissions in pulverized fuel (coal and char) combustion through preheating with a circulating fluidized bed. The high-temperature preheated fuel particles obtained from the circulating fluidized bed would be burned in the down-fired combustor. The focus of research is the trend of NOx emissions with different air distribution through varying secondary air nozzle structures and air ratios as well as tertiary air positions along the down-fired combustor. Under the stable operation, the burning temperature was uniform and the combustion efficiency was high. When the fuel was pulverized coal, the NOx emissions with the secondary air center nozzle structure were almost twice of that with ring nozzle structure. Furthermore, the NOx emissions increased with the secondary air ratio increasing when the nozzle structure was center. However, there was a minimum NOx concentration when the nozzle structure was ring. And the lower NOx emissions were achieved through arranging the tertiary air distribution rationally. In addition, the trend in NO concentration along the down-fired combustor was almost the same irrespective of the fuel (coal or char). But the char combustion efficiency should be paid more attention when the tertiary air position was changed.

更新日期：2018-06-18
• Energy Fuels (IF 3.091) Pub Date : 2018-06-18
Jianping Yan, Shaolong Zhang, Jun Wang, Qinhong Hu, Min Wang, Jing Chao

The complexity of shale pore structure, which can be assessed by fractal dimension, will affect the percolation and reservoir capability of shale, thus, it is of great significance for shale reservoir evaluation. To investigate the pore structure and fractal characteristics of lacustrine shale, a combination of X-ray diffraction (XRD), total organic carbon (TOC), scanning electron microscope (SEM), mercury-injection capillary pressure (MICP), nuclear magnetic resonance (NMR) and Nano-CT experiments were performed on shale samples from the lower sub-member of the third member of the Eocene Shahejie Formation (Es3L) in Zhanhua depression, Bohai Bay Basin. Based on fractal theory, fractal dimensions of analyzed shale samples were determined by T2 spectrum from NMR experiment. The relationships between fractal dimension and mineral content, TOC and pore structure parameters were discussed. The results indicate that the pore structure of lacustrine shale in the study area is complex to exhibit a strong heterogeneity. Pore types mainly include intergranular pores, intragranular pores, as well as some dissolved pores and microfractures. Calcite and clay are the dominant minerals, ranging from 9% to 91% (averaged 52.23%) and from 1% to 48% (averaged 18. 63%), respectively. TOC contents are relatively high with values from 0.06% to 9.32%. Calculated fractal dimension (D) values are between 2.2544 and 2.439, which exhibit positive correlations with TOC content, quartz content and clay mineral content. In contrast, negative relationship occurs between fractal dimension and calcite content, indicating dissolved pores with large pore size developed in shale samples could reduce the heterogeneity of pore size distribution. Negative correlations are observed between T2 cutoff value, T2 geometric mean and porosity versus fractal dimension, while displacement pressure (Pd) and fractal dimension exhibits a positive correlation trend. The different relationships suggest that fractal dimension is closely related to pore structure, namely, shale samples have a better pore structure to show a smaller fractal dimension. Four typical samples were chosen to verify the relationship between fractal dimensions and pore structure in logging profile of Well L69. Prefect application results were obtained, suggesting that the fractal dimension can be used to indicate the effectiveness of reservoir in the study area.

更新日期：2018-06-18
• Energy Fuels (IF 3.091) Pub Date : 2018-06-17
Ahmed A. Abdelhafez, Medhat Ahmed Nemitallah, Sherif S. Rashwan, Mohamed A. M. Habib

Premixed oxygen-enriched air-methane flames (CH4/O2/N2) are compared to their oxy-methane counterparts (CH4/O2/CO2) in the same model gas-turbine combustor and under identical conditions of oxygen fraction (OF=21–70%vol.) and equivalence ratio (φ=0.2–1.0). The flow rates of non-preheated reactant gases were adjusted for each tested flame to sustain a common bulk velocity at burner throat throughout the whole study, in order to maintain similar flow conditions and turbulence intensities for all isothermal flow fields. The flashback and blowout limits were quantified to identify the combustor stability maps within the OF-φ space. The adiabatic flame temperature (Tad) was also mapped over the same test ranges for both N2 and CO2 flames. The effect of Tad on flame macrostructure and stabilization mode was studied in detail by imaging selected flames. The following novel findings were found to apply to both N2 and CO2 flames at common inlet bulk velocity: Their stable combustion zones can both be characterized by Tad only, although they have different Tad maps. Combustion is thus governed mainly by the reaction kinetics (especially near the flashback limits) under similar cold flow conditions. Both N2 and CO2 flames undergo the same changes in macrostructure and stabilization mode as Tad is increased from the blowout limits to the flashback ones. Stable flames of different φ and OF but the same Tad have identical shapes, which shows the direct dependence of flame macrostructure and stabilization mode on Tad under similar cold flow conditions. Both N2 and CO2 stability maps can be subdivided into sub-zones based on Tad only, where each zone has a single prevailing flame macrostructure irrespective of φ and OF. This is yet another proof that Tad is an excellent tool for predicting flame macrostructure at constant inlet bulk velocity. Based on these findings, this study recommends to design and operate future oxy-fuel gas-turbine combustors based on Tad (and not OF or φ), particularly at high and medium loads away from blowout, following the existing common practice among manufacturers of conventional lean-premixed air-fuel gas turbines to quantify combustor performance in terms of Tad.

更新日期：2018-06-18
• Energy Fuels (IF 3.091) Pub Date : 2018-06-17
Shanshan Cao, Changchun Zhou, Jin-he Pan, Cheng Liu, Mengcheng Tang, Wanshun Ji, Tingting Hu, Ningning Zhang

Rare earth elements (REEs) are very important strategic resources, but the traditional high-quality rare earth resources are becoming increasingly scarce. Coal fly ash (CFA) in some areas in the world has a high REEs content, which can be a potential supplement to the rare earth resources. CFA samples collected from the Panbei Power Plant in Guizhou Province of China, in which the REEs content is 489 ppm, was used as the research object in this study. Taking three REEs (Lanthanum (La), Cerium (Ce), and Neodymium (Nd)) with the highest content in this CFA sample as the representative and hydrochloric acid as the leaching reagent, the effects of various factors on the leaching efficiency of REEs from CFA were investigated systematically. Further, two unreacted core shrinkage models (chemically controlled model and diffusion controlled model) were used to study the leaching kinetics of REEs from CFA. The results showed that except for the small influence of stirring speed, the temperature, acid concentration, liquid-solid ratio, and reaction time all have a great influence on the leaching efficiency of REEs. Leaching efficiency of 71.9, 66.0, and 61.9% for La, Ce, and Nd, respectively, was obtained under the conditions of a stirring speed of 200 rpm, temperature of 60 °C, HCl concentration of 3 M, liquid-solid ratio of 10 (v/m), and leaching time of 120 min. The leaching mechanism of REEs from CFA tends to be more controlled by chemical reactions. In addition, La is more easily leached from CFA than Ce and Nd. This study can provide theoretical guidance for optimizing the leaching conditions of REEs from CFA at low temperature and atmospheric pressure, thereby provide theoretical support for the early industrial development and utilization of rare earth resources in CFA.

更新日期：2018-06-18
• Energy Fuels (IF 3.091) Pub Date : 2018-06-17
Hayder A. Alalwan, Sara E. Mason, Vicki H. Grassian, David M. Cwiertny

Through continuous flow reactor experiments, materials characterization and theoretical calculations, we provide new insights into the reduction of hematite (α-Fe2O3) nanoparticles by methane (CH4) during chemical looping combustion (CLC). Across CLC-relevant temperatures (500 to 800 ○C) and gas flowrates (2.5 to 250 h-1), decreasing α-Fe2O3 particle size (from 350 to 3 nm) increased the duration over which CH4 was completely converted to CO2 (i.e., 100% yield). We attribute this size-dependent performance trend to the greater availability of lattice oxygen atoms in the near-surface region of smaller particles with higher surface area-to-volume ratios. All particle sizes then exhibited a relatively rapid rate of reactivity loss that was size- and temperature-independent, reflecting a greater role for magnetite (Fe3O4), the primary α-Fe2O3 reduction product, in CH4 oxidation. Bulk (X-ray diffraction; XRD) and surface (X-ray photoelectron spectroscopy; XPS) analysis revealed that oxygen carrier reduction proceeds via a two-stage solid-state mechanism; α-Fe2O3 reduction to Fe3O4 followed the unreacted shrinking core model (USCM) while subsequent reduction of Fe3O4 to wüstite (FeO) and FeO to iron metal (Fe) followed the nucleation and nuclei growth model (NNGM). Atomistic thermodynamics modeling based on density functional theory supports that reduction initiates via the UCSM, as partially reduced α-Fe2O3 surfaces exhibited a wide range of stability relative to bulk Fe3O4. Reduction and reoxidation cycling experiments were also performed to explore more practical aspects related to the long-term performance of unsupported α-Fe2O3 nanoparticles as oxygen carriers for CLC.

更新日期：2018-06-18
• Energy Fuels (IF 3.091) Pub Date : 2018-06-15
Mehdi Sedighi, Majid Mohammadi, Mojtaba Sedighi, Mostafa Ghasemi

Asphaltene deposition is crucial for the production and refining of crude oil. Numerous studies have been carried out to prevent asphaltene deposition using inhibitors which not only show great effectiveness in suppressing asphaltene precipitation but are also environmentally friendly. In accordance with this objective, the effect of NiO/ZSM-5 nanocomposites as an innovative green adsorbent was experimentally tested to eliminate asphaltene from a model oil solution. This adsorbent is synthesized via an eco-friendly template. The morphological nanocomposite was detected using Fourier transform infrared analysis, X-ray diffraction, transmission electron microscopy, as well as Brunauer–Emmett–Teller analysis. The batch experiments were developed using central composite design (CCD), which can optimize the most important parameters to maximize the removal percentage. An R2 value of 0.95 was obtained from the regression analysis of the experiments, which showed close accordance between the experimental and the model data. On the basis of RSM, the removal efficiency of asphaltene was 90.35% with an predicted optimum of D/C = 0.072 [(g)adsorbent/(mg/L)initial], pH = 4.80, and temperature = 298 K. Isotherms were identified and verified using the factor RL. The double exponential model was employed to evaluate the kinetics process. Additionally, the importance of asphaltene removal and financial analysis is appraised in regard to stock returns of oil and petrochemical companies after asphaltene removal.

更新日期：2018-06-16
• Energy Fuels (IF 3.091) Pub Date : 2018-06-15
Nadia Sebbar, Thorsten Zirwes, Peter Habisreuther, Joseph William Bozzelli, Henning Bockhorn, Dimosthenis Trimis

The paper presents a study on the combustion (oxidation) of S2 over a wide range of air/fuel ratios using a sulfur oxygen mechanism and numerical flame calculations; reaction zone structures, as well as the corresponding laminar burning velocities are reported. The numerical simulations employed a detailed reaction mechanism derived from an H/O/S-combustion mechanism from literature after removing all reactions of hydrogen containing species. Using reaction rate coefficients from literature in the calculations brings about a very high burning velocity in the order of 300 cm s-1 at T0 = 373 K and under stoichiometric conditions. Sensitivity analysis of the computed results was used to evaluate which reaction rate has crucial influence on the burning velocity and flame structure. It turned out that the sensitivity coefficients of burning velocity with respect to the rate coefficient of reaction S + O2 → SO + O are by far the largest ones. Further investigations have been performed based on different rate constants of reaction S + O2 → SO + O taken from literature and from own calculations. The results show a high dependency of burning velocity and flame structure on the reaction rate coefficient of this reaction and the obtained significant changes in burning velocities as well as in species profiles provides more information on the importance of this reaction. This work constitutes a necessary first step towards a validated reaction mechanism for the combustion of sulfur.

更新日期：2018-06-16
• Energy Fuels (IF 3.091) Pub Date : 2018-06-15
Stephen Niksa

This paper introduces a FLASHCHAIN®-based reaction mechanism for oils production during tar hydroconversion with any coal for any hydrogasification conditions. Oils are generated by the hydrogenation of tar monomers in two stages. In the first stage, the tar monomers released as primary tars are rapidly hydrogenated into oils at the monomer hydrogenation rate. Since elevated pressures always shift primary tar molecular weight distributions toward lighter species, monomers constitute substantial fractions of primary tar, and as much as half the ultimate oils yield is produced soon after the onset of tar hydroconversion. In the second stage, additional tar monomers are gradually released by hydrocracking of larger tar molecules and then hydrogenated into oils, while control of the oils production rate shifts from monomer hydrogenation to hydrocracking. Oils yields are uniform with H2 pressures higher than 1 MPa because rates of monomer hydrogenation and hydrocracking accelerate for progressively higher H2 pressures to compensate for diminishing primary tar yields. Predicted oils yields grow for progressively hotter temperatures. The analysis shows that aliphatic tar components must be incorporated into oils along with their aromatic nuclei during monomer hydrogenation, and constitute half or more of the oils yield at the highest H2 pressures. Primary tar composition and, especially, their structural components determine the maximum oils yields from different coals. The sample-to-sample variability in primary tar yields is apparent in their associated oils yields. In combination, the mechanisms for hydropyrolysis, tar hydroconversion, and char hydrogasification accurately interpreted a database representing coals of rank from lignite to anthracite; heating rates from 1 to 104 °C/s; temperatures from 475 to 900 °C; coal contact times from 1 to 900 s; gas contact times from 2 to 42 s; and H2 pressures from 0.3 to 15 MPa.

更新日期：2018-06-16
• Energy Fuels (IF 3.091) Pub Date : 2018-06-15
Haichao Wang, Xuehai Fu, Xiaoyang Zhang, Qinghe Niu, Yanyan Ge, Jijun Tian, Xiaoqian Cheng, Ning Chen, Xiaolin Hou, Hua Du

Groundwater is one of the important factors controling the accumulation and exploitation of coal measures gas. In this work, a water source identification method based on hydrochemistry, stable isotope, 129I and 14C dating is first established; then, the source, age, and evolution of coal measures water in the Central-South Qinshui Basin are clarified. The results reveal that the hydrogeological environment of coal measures water in Carboniferous-Permian is between semiclosed and open, with free water exchanging. The coal measures water in the Guxian and Shizhuangnan blocks are Ca-HCO3 and Na-HCO3 types, respectively, while the closed coefficients are 1.77 and 322.75, respectively. Therefore, the water is attributed to river water or shallow groundwater in the Guxian block and deep groundwater in the Shizhuangnan block. The age of coal measures water is 1.51–20.61 Ma, which indicates that the water in coal measures at the present stage is a mixture of a little paleo sedimentary water and massive modern meteoric water and that the modern meteoric water recharge lasted until 1950. The above achievements deepen the understanding of the coal measures reservoir type and also guide the optimal selection and co-exploration and -exploitation of coal measures gas.

更新日期：2018-06-15
• Energy Fuels (IF 3.091) Pub Date : 2018-06-15
Ming Sun, Dan Zhang, Qiuxiang Yao, Yongqi Liu, Xiaoping Su, Charles Q Jia, Qingqing Hao, Xiaoxun Ma

Composition analysis of coal tar remains a challenging task because of its complex components. In this paper, the compositions of low temperature coal tar (LTCT) and the wash oil fraction of high temperature coal tar (HTCT) were studied. The thermogravimetric analyzer (TG) combined with gas chromatography-mass spectrometry (GC/MS) with the same temperature program was put forward to analyze the quantitative determination of the GC/MS analyzable part of coal tar, and the composition and distribution of the GC/MS unanalyzable part (300LTCT and 300HTCT obtained from TG at the final temperature of 300oC) was investigated by a pyrolysis gas chromatography-mass spectrometer (Py-GC/MS). Results reveal that light compositions can be more effectively extracted by petroleum ether (PE) than heavy compositions. PE soluble fractions of LTCT and HTCT cannot be totally gasified by GC/MS and the remaining parts at above 300 oC are 6.51 w% and 4.99 w%, respectively. GC/MS combined with TG can accurately analyze the composition of ≤300 oC fractions in coal tar. Four dehydrogenation reactions were presented in the fast pyrolysis process of coal tar. An intermolecular association occurs in 300HTCT. 300LTCT is mainly composed of phenols, aliphatics, and aromatics. The composition analysis of 300LTCT and 300HTCT by Py-GC/MS indicates that there are some bridge bonds in macromolecular structure of coal tar and they have broken down to produce small molecular weight of phenolic compounds and aromatic hydrocarbons during pyrolysis.

更新日期：2018-06-15
• Energy Fuels (IF 3.091) Pub Date : 2018-06-14
Yang Yue, James R. Kastner, Sudhagar Mani
更新日期：2018-06-15
• Energy Fuels (IF 3.091) Pub Date : 2018-06-14
Noémi A. Buczkó, Tamás Varga, István Gy. Zsély, Tamás Turányi

A re-evaluation of the flow reactor experiments of Abián et al. (Abián, M.; Alzueta, M. U.; Glarborg, P. Formation of NO from N2/O2 Mixtures in a Flow Reactor: Toward an Accurate Prediction of Thermal NO. Int. J. Chem. Kinet. 2015, 47, 518−532, DOI: 10.1002/kin.20929) is presented. In these experiments, nitrogen oxide formation was measured at atmospheric pressure in the temperature range of 1700–1810 K using several mixtures containing different ratios of oxygen, nitrogen, and water vapor. On the basis of the mechanism of Abián et al., the two most important reaction steps for NO formation (reaction R1, NO + N = N2 + O; reaction R2, N2O + O = 2 NO) were identified by local sensitivity analysis. For the optimization of the Arrhenius parameters of these reaction steps, 25 data points measured by Abián et al., two direct rate coefficient measurements (73 data points), and one theoretical calculation were used. The obtained mechanism with the optimized Arrhenius parameters (reaction R1, A = 1.176 × 1010 cm3 mol–1 s–1, n = 0.935, and E/R = −693.68 K; reaction R2, A = 1.748 × 1016 cm3 mol–1 s–1, n = −0.557, and E/R = 14 447 K) described the results of the flow reactor experiments, direct measurements, and theoretical calculations much better compared to the Abián et al. mechanism and also several recent NOx mechanisms. The rate coefficients of these elementary reactions were obtained with low uncertainty in the temperature range of 1600–2200 K.

更新日期：2018-06-15
• Energy Fuels (IF 3.091) Pub Date : 2018-06-14
Hong Xiao, Tie-Guan Wang, Meijun Li, Jian Fu, Youjun Tang, Shengbao Shi, Zhe Yang, Xiaolin Lu

Two unusual tricyclic terpanes (compounds X and Y) and four tetracyclic terpanes (compounds X1, Y1, Z, and Z1) have been detected in crude oils from the Pearl River Mouth, Beibuwan, and Liaohe basins in China. On the basis of their elution order, relative retention times in m/z 191 mass chromatograms, and their diagnostic ion fragments, we have identified two tricyclic terpanes (marked by peaks X and Y in previous literature) as C21 and C25 tricyclic terpanes and four tetracyclic terpanes (marked by peaks X1, Y1, Z, and Z1) as C24-des-A-lupane, C24-des-A-oleanane, C24-des-A-ursane, and C27 tetracyclic terpane, respectively. These six compounds have similar characteristics to oleanane, ursane, and lupane in their chemical structure and are considered likely to originate from alcohols or ketone precursors present in higher plants. The high abundance of these tri- and tetracyclic terpanes is probably related to the distinctive contribution of higher plant material in the organic matter content of source rocks. In addition, the redox conditions and water depth in the depositional environment significantly impact the distribution patterns of the compounds, and it is possible that they are readily formed under oxidation conditions. Because of their unique biological origin and prominent geochemical significance, they may have potential application in oil–source correlation and the classification of crude oil families.

更新日期：2018-06-15
• Energy Fuels (IF 3.091) Pub Date : 2018-06-14
Mario Morgalla, Leteng Lin, Michael Strand

This Article investigates the decomposition of benzene (as a model tar) over finely dispersed char particles continuously distributed into a packed bed. Fragmented char particles and benzene plus a gasification agent (H2O or CO2) were supplied into a ceramic reactor that was heated electrically. The supplied char particles were retained in the reactor by a bed of alumina grains. Woody char as well as iron-doped and potassium-doped woody char were used. The influence of the gasification agent, char concentration, char weight time (proportional to the instant char mass present in the bed), and bed temperature (600–1050 °C) was investigated. Increasing the char concentration and char weight time increased benzene conversions for all tested chars. At similar char weight times, the benzene conversion increased with temperature, whereas the iron- and potassium-doped char did not affect the specific conversion. At similar char concentrations, changing the gasification agent from CO2 to steam as well as using doped char led to decreased benzene conversions. This can be explained by accelerated char gasification reactions and thus a diminished char mass in the packed bed. Furthermore, benzene conversion rates were enhanced in the presence of CO2 as compared to steam. As the temperature was increased from 950 to 1050 °C, the benzene conversions were slightly reduced. This was interpreted as a combined effect of the enhanced benzene conversion rates and reduced char weight times. The highest benzene conversions achieved in the experiments were approximately 80% at 950–1000 °C using CO2 as gasification agent and supplying approximately 20–30 g N m–3 undoped woody char.

更新日期：2018-06-15
• Energy Fuels (IF 3.091) Pub Date : 2018-06-14
Mohammadhadi Nakhaei, Morten Nedergaard Pedersen, Hao Wu, Lars Skaarup Jensen, Peter Glarborg, Peter Arendt Jensen, Damien Grévain, Kim Dam-Johansen

Physical and aerodynamic characteristics of several refuse derived fuel (RDF) samples were studied. Each RDF sample was tested in a wind sieve to classify the particles into different fractions according to their terminal velocity. The individual particles from the wind sieve were then manually separated according to the material type and physically characterized by weight measurement and 2D photographing. For the tested samples, despite the overall weight distribution of the fractions from the wind sieve being similar, the material distribution of particles in each fraction was significantly different. It has been shown that, regardless of the particle material, for each group of particles from the wind sieve test, the ratio of particle maximum projected area to particle mass lies in a narrow range. A new approach based on the particle maximum projected area was proposed to predict the terminal velocity of particles and was tested for each group of particles from the wind sieve experiment. The maximum deviation of the mass-based averaged terminal velocity predicted from the drag model compared to the mid-point wind sieve velocity was smaller than 14%. A procedure was proposed for physical characterization of RDF particles based on the wind sieve test and 2D imaging of particles. This characterization can be used as an input for computational fluid dynamics (CFD) calculations of RDF-fired cement calciners and rotary kilns.

更新日期：2018-06-15
• Energy Fuels (IF 3.091) Pub Date : 2018-06-14
Xiaomeng Wang, YASAR DEMIREL

Sustainability metrics, cradle-to-gate life cycle assessment, and techno economic evaluation have been presented for an optimized entrained flow coal oxy-combustion plant with carbon capture producing power, and methanol. The aim of the study is to assess the feasibility of co-producing methanol in a coal-based power plant with entrained flow coal gasification system. Coal-based methanol economy, as an attractive liquid transportation fuel as well as an essential intermediate chemical feedstock, can fill a possible gap between declining fossil fuel supplies and movement toward the hydrogen economy. Within the plant, firstly, the coal is fed to a pyrolysis reactor, and the volatile matter is fed into an oxy-combustion reactor, while the char is gasified in an entrained flow gasifier. The remaining char is gasified. The heat is used to produce electricity, while the syngas is converted to methanol. The integral plant consisting of an air separation unit, oxy-combustion of coal, gasification of char, electric power production, carbon capture and conversion to methanol has been designed and optimized by using the Aspen Plus package. The optimization includes the design specification, process heat integration using energy analyzer toward a more efficient clean-coal technology with methanol production. The plant uses 500 MT/day Powder River Basin coal, 2231.03 MT/day of air and produces 40.11 MWh of electric power and 207.99 MT/day of methanol. The total amount of captured CO2 is 589.75 MT/day and 1309.33 MT/day of nitrogen are also produced. A multi-criteria decision matrix consisting of economic indicators as well as the sustainability metrics is developed to assess the feasibility of the extended plant. Methanol production beside the power production may improve the overall feasibility of coal- powered plants.

更新日期：2018-06-15
• Energy Fuels (IF 3.091) Pub Date : 2018-06-14
Nicola Bianco, Manosh C. Paul, George Brownbridge, Daniel Nurkowski, Ahmed M. M. Salem, Umesh Kumar, Amit N. Bhave, Markus Kraft

This article aims to combine physico-chemical modelling to statistical analysis algorithms to provide alternative advanced approach for the optimisation of biomass pyrolysis and gasification processes. The goal was to develop an automated flexible approach for the analyses and optimisation of these processes. The approach can also be directly extended to other biomass conversion processes, and in general to all those processes for which a parameterised model is available. A flexible physico-chemical model of the process is initially built. Within this model, a hierarchy of sensitive model parameters and input variables are identified, which are then automatically adjusted to calibrate the model and optimise the process. Through the mathematical model of the process we can understand how species concentration and reactor conditions evolve in the system under study. The flexibility given by the ability to control any parameter of the model is critical in providing the capacity to effectively control both the efficiency of the process and its emissions. It allows users to design and operate feedstock-flexible pyrolysis and gasification processes, accurately control product characteristics, and limit or prevent the formation of unwanted by-products (e.g. tar in biomass gasification processes).

更新日期：2018-06-15
• Energy Fuels (IF 3.091) Pub Date : 2018-06-14
Ashwin Kumar Yegya Raman, Clint Philip Aichele

Efficient phase separation of oil and water in emulsions is critical for water treatment processes and hydrocarbon processing. Our research aims at elucidating the separation of water-in-oil emulsions using silica nanoparticles (SNP’s). By probing the surfactant-nanoparticle interactions, we showed that surfactant stabilized emulsions can be destabilized depending on the nanoparticle wettability and the mode of nanoparticle addition. The efficiency of nanoparticles to demulsify surfactant stabilized emulsions depended on both the nanoparticle and surfactant concentration. Water-in-oil emulsions were destabilized when partially hydrophobic nanoparticles were added to the surfactant-stabilized emulsion after emulsion formation (post-mixing). Hydrophilic and partially hydrophobic nanoparticles adsorb the surfactants via hydrogen bonding that in turn leads to depletion of surfactants at the oil-water interface. Upon the addition of hydrophilic nanoparticles, the preferential distribution of nanoparticles in the water phase led to lower adsorption of surfactants from the oil phase resulting in inefficient destabilization as compared to partially hydrophobic nanoparticles. Water-in-oil emulsions were not destabilized upon post-mixing hydrophobic nanoparticles due to weak hydrophobic interactions between surfactants and hydrophobic nanoparticles. For a fixed concentration of nanoparticles of specific wettability, changing the mode of nanoparticle addition altered the flow behavior and the network strength of surfactant stabilized water-in-oil emulsions.

更新日期：2018-06-15
• Energy Fuels (IF 3.091) Pub Date : 2018-06-14
Shoutao Ma, Jinfang Li, Lumin Li, Xianyong Shang, Shikai Liu, Changyong Xue, Lanyi Sun

The separation of benzene and cyclohexane is considered as one of the most challenging processes in the petrochemical industry. In this paper, low transition temperature mixtures (LTTMs) were used as solvents for the separation of benzene and cyclohexane. The selected LTTMs were sulfolane - tetrabutylammonium bromide 5:1 and ethylene glycol - trimethylamine hydrochloride 5:1, and liquid-liquid equilibrium (LLE) data of benzene-cyclohexane-LTTMs were experimentally determined at 40oC under normal atmosphere. Moreover, the effects of the mole ratio of hydrogen bond donor (HBD) sulfolane and hydrogen bond acceptor (HBA) tetrabutylammonium bromide on extraction performance were also observed based on the LLE data. It is found that when the mole ratio of sulfolane to tetrabutylammonium bromide is 5:1, LTTM has the best extraction performance. In addition, the LLE data of benzene-cyclohexane-LTTMs ternary system were used to fit parameters of the NRTL activity coefficient model. Based on the NRTL model the continuous extraction process was simulated and the operating parameters were obtained, and high product purity (cyclohexane 0.997) and high recovery efficient (cyclohexane 93.28% and benzene 98.25%) can be achieved. In conclusion, the LTTM sulfolane - tetrabutylammonium bromide 5:1 is a promising solvent for the extractive separation of benzene-cyclohexane mixtures.

更新日期：2018-06-15
• Energy Fuels (IF 3.091) Pub Date : 2018-06-14
Venkat Pranesh, S. Balasubramanian, S. Mahalingam, S Ravikumar, T. Christo Michael, B. Kanimozhi

In this paper, we introduce a novel and unprecedented solid fuel known as benzoic resin, which is equivalent to coal. Here, we focus on the ignition behavior of benzoic resin, and for this purpose, we have employed an induction heating plate equipped with a liquefied petroleum gas flame ignitor. Additionally, an analytical model was also developed to estimate the ignition rate of this solid fuel. Experiments were carried out for various induction heating surface temperatures, such as 70, 100, 130, 160, 210, 240, and 270 °C. The Fourier transform infrared spectral studies of benzoic resin exhibited two sharp peaks at a lower wavenumber. The calorific value of benzoic resin is found to be 26 004.92 kJ/kg, which is higher than lignite and bituminous coal, except anthracite. The ignition and volatile initial release temperatures were found to be 70 and 90 °C, respectively, where these values are better than the other coal types. Also, the electrical conductivity of benzoic resin was measured to be 1620 μs/cm, which is quite higher than the low- and medium-rank coals. The main experimental results revealed a linear variation of the heat release rate for varying surface induction steel plate temperatures. A visible ignition was detected at the surface temperature of 70 °C and the highest heat release rate of 260 J/s, which was achieved at 270 °C surface temperature. Furthermore, a soaring heat release rate was accomplished for an increasing combustion time, and also, good emission characteristics were quantified. Additionally, the ignition and heat release rate results were compared to other standard ASTM methods using an electric Bunsen burner and Meker–Fisher burner, which showed close correlation.

更新日期：2018-06-14
• Energy Fuels (IF 3.091) Pub Date : 2018-06-13
Marfa Nazarova, Patrick Bouriat, Patrice Creux

Expanding the electrical double layer of minerals through low-salinity brine injection has been suggested as a possible enhanced oil recovery mechanism. To investigate this theory, we measured the ζ potential of different minerals, namely, sands from Fontainebleau, Ottawa, and Landes, a sample from a sandstone outcrop, and one crude oil. ζ-potential measurements can be used to quantify the surface charges of materials; therefore, experiments associated with this technique were performed to predict the behavior of repulsion or attraction between materials in different salinity and pH conditions. We showed that there is no significant difference between the ζ potentials of the tested materials. We did, however, observe that the different sands and sandstone have dissimilar adhesion behaviors. No correlation was found between the electrokinetic measurements performed on the minerals and their response to crude oil introduced into the system. The adhesion results obtained for the Landes and Ottawa sands were perfectly in line with what was expected from ζ-potential measurements, but the Fontainebleau sand and sandstone exhibited different behaviors. For the tested minerals, we showed that ζ-potential changes may not be only responsible for a low-salinity brine effect concerning a system oil/brine/rock systematically characterized in a coreflood with an observed additional recovery.

更新日期：2018-06-14
• Energy Fuels (IF 3.091) Pub Date : 2018-06-13
Helga Kovacs, Zsolt Dobo, Tamas Koos, Adrienn Gyimesi, Gabor Nagy

The influence of the flue gas temperature on the concentration of metals in fly ash and deposited ash during heavy-metal-contaminated woody biomass combustion was investigated. The biomass gathered from heavy-metal-contaminated soil was combusted in a 34 kWth boiler, and the metal flow was monitored through the metal content of solid residues for up to 30 elements. The flue gas temperature was controlled by the heat exchanger, and it was found that, by decreasing the temperature, more metals can be kept inside the combustion system, potentially lowering the environmental heavy metal pollution because more metal volatiles are being condensed on fly ash particles, which can be separated using known filtration techniques. The concentrations of Ag, Co, Cr, Cu, Fe, Ga, Mg, Mn, Ni, Pb, Si, Sn, Ti, V, and Zr were significantly higher in fly ash samples collected at 150 °C flue gas temperature compared to the 250 °C case, indicating a strong temperature dependence. A minor temperature dependence was observed in deposited ash samples for most elements. On the basis of the results, decreasing the flue gas temperature is a viable method for lowering metal emission during contaminated woody biomass combustion.

更新日期：2018-06-14
• Energy Fuels (IF 3.091) Pub Date : 2018-06-13
Zheng Zhong, Yitong Zhai, Xueyao Zhou, Beibei Feng, Chengcheng Ao, Lidong Zhang

2-Methyl-1-butanol (2M1B) is a favorable candidate of substitute fuels characterized with high energy density and low hygroscopicity. 2M1B radicals, which are the products of H-abstraction reactions of 2M1B, and their isomerization and decomposition reactions play a cardinal impact on the distribution of combustion products. In this work, the primary isomerization and decomposition reaction channels of 2M1B radicals were investigated by using QCISD(T)/CBS//M062x/cc-pVTZ and CBS-QB3 method, respectively. The accurate phenomenological temperature- and pressure-dependent rate constants covering temperatures of 250–2500 K and pressures from 1 × 10–3 to 1 × 103 bar along with high-pressure limit rate constants for these channels were computed by solving the RRKM/master equation. The calculations revealed that the isomerization reaction of RC2 → RC6 has the highest energy barrier among these reactions, while the decomposition reaction RC6 → CH3CH2CHCH3 + CH2O has the lowest energy barrier. Furthermore, the computed rate coefficients were also validated by using the previous pyrolysis experiment. The modeling results reproduce the experimental results satisfactorily. The current work not only provides reasonable kinetic data for the development of 2M1B combustion models but also lays a foundation to extend the kinetic mechanisms of alcohol with a longer chain.

更新日期：2018-06-14
• Energy Fuels (IF 3.091) Pub Date : 2018-06-13
Wattana Chaisoontornyotin, Jingzhou Zhang, Samson Ng, Michael P. Hoepfner

Inorganic solids are often present in real heavy oil systems, but are typically absent in asphaltene laboratory studies. For the first time, we investigate the influence of inorganic solids on the kinetic precipitation of asphaltenes. In contrast to potentially slow kinetics in homogeneous liquid petroleum mixtures, rapid kinetic precipitation of asphaltenes was observed when inorganic solids were present in the system. A combined homogeneous aggregation and diffusion-limited heterogeneous nucleation model was developed to quantify the rate of asphaltene precipitation under the explored experimental conditions. The rate of heterogeneous nucleation was generally observed to be faster than the rate of homogeneous aggregation; however, this trend was reversed as the solvent strength decreased and greater quantities of asphaltenes precipitated. The inorganic solids were characterized, and kaolinite clay was observed in the studied samples. This investigation leads to a clearer understanding of the complex asphaltene aggregation process that occurs in real and heterogeneous systems. The competing pathways of asphaltene precipitation provide novel insight into asphaltene precipitation and deposition, in addition to new experimental strategies to measure asphaltene solubility.

更新日期：2018-06-14
• Energy Fuels (IF 3.091) Pub Date : 2018-06-13
Jafar Azamat, Alireza Khataee
更新日期：2018-06-14
• Energy Fuels (IF 3.091) Pub Date : 2018-06-13
Fushui Liu, Yongli Gao, Han Wu, Zheng Zhang, Xu He, Xiangrong Li

Gasoline addition in diesel fuel could not only improve the overall energy efficiency, but also could reduce the soot emission on diesel engine. However, the influence of gasoline on the soot forming characteristics has not been revealed fundamentally. A liquid burner system, modified from a Gülder burner, was applied to create strict laminar diffusion flame to carry out the related study. And, optical diagnostics technologies including digital camera imaging and high speed two-dimension line-of-sight attenuation (2D-LOSA), were used to record the natural luminosity flame structure, smoke point, and soot volume fraction. During experiments, the diesel ratio was varied as 0%, 20% and 40% by volume, while fuel flow rate was varied from 6g/h to 9g/h. The results show that diffusion flames of blends can be distributed into typical three parts, soot free region, soot growth region, and soot oxidation region. With the fuel flow rate increasing more soot was generated and the flame height was lifted. With diesel ratio increasing in gasoline/diesel blends, the visible flame height decreased, flame luminosity intensity decreased, smoke point increased, and 2D soot volume fraction value reduced, which indicates that diesel is less likely to produce soot than gasoline in the laminar diffusion flame. The soot reducing effect of diesel is regarded because diesel can enhance the cool flame combustion in free soot region due to its more obvious NTC (Negative Temperature Coefficient) effect. It is also reasonable to expound that the soot emission reduces with addition of gasoline in diesel on engines is mostly because of its volatility rather than its chemical characteristics.

更新日期：2018-06-14
• Energy Fuels (IF 3.091) Pub Date : 2018-06-13
Bin Zhang, Anna Bogush, Jiangxiong Wei, Weiting Xu, Zhengxiang Zeng, Tongsheng Zhang, Qijun Yu, Julia Anna Stegemann

The fate of heavy metals during clinkerization is of crucial significance to the utilization of solid waste as fuels and raw materials in cement kiln producing clinker. A ternary system of clinker-heavy metal-chlorine was developed that is more coincident with the condition of co-processing of solid waste in cement kiln. The main goal of this study was to investigate the relationships among chlorine, volatilization and solidification of Cu/Pb, and mineral phases of the clinker during clinkirization. The AlCl3·6H2O (chlorine source) and PbO/CuO were mixed with cement raw meal in appropriate ratios to produce co-processed clinkers. The volatilization and solidification of Pb and Cu were investigated experimentally using a combination of atomic absorption spectrometry, electron probe micro-analysis, scanning electron microscopy with energy-dispersive X-ray spectroscopy, optical microscope, thermogravimetric and X-ray diffraction quantitative analyses. The volatilization ratios of Pb and Cu increased up to 46.18% and 34.04%, respectively, with increasing AlCl3·6H2O content up to 1.6%. comparing to the cement mixtures without AlCl3·6H2O addition (Pb and Cu volatilisation ratios are 49.90% and 27.21%, respectively). Pb and Cu oxides can be transformed into Pb and Cu chlorides, that are not stable and have high vapor pressure. Pb and Cu are mainly concentrated in the interstitial phases of the clinker. The addition of AlCl3·6H2O led to increase the crystal size of alite and belite. X-ray diffraction quantitative analyses proved that the content of silicate phase increased with the corresponding content of interstitial phases decreased during clinkerization with the addition of AlCl3·6H2O, that decreased the ability of clinker to solidify Pb and Cu in the produced clinkers. This research can help to promote understanding of the fate of heavy metals during the cement kiln co-processing of solid wastes and meaningfully for energy conservation and sustainable development.

更新日期：2018-06-13
• Energy Fuels (IF 3.091) Pub Date : 2018-06-12
C. M. Grottola, P. Giudicianni, J. B. Michel, R. Ragucci

Biomass for energy production has been extensively studied in the recent years. To overcome some constraints imposed by the chemical–physical properties of the biomass, several pretreatments have been proposed. Torrefaction is one of the most interesting pretreatments because torrefied biomass holds a wide range of advantages over raw biomass. The devolatilization of water and some oxygenated compounds influences the increase in the calorific value on both a mass and volumetric basis. The increase in the density reduces the transportation costs. Moreover, the decreased moisture content increases the resistance of biomass to biological degradation, thus facilitating its storage for long periods. Under torrefaction conditions, approximately 10–40 wt % of the initial biomass is converted into volatile matter, including liquid and non-condensable combustible gases. The energy efficiency of the process could greatly benefit the exploitation of the energy content of these products. Recent studies and technological solutions have demonstrated the possibility to realize polygeneration systems that integrate torrefaction/pyrolysis to a combustion process with the aim of obtaining torrefied material/biochar and/or energy from biomass. Some examples include Pyreg, Pyreg-Aactor GT, TorPlant, and Top Process. The identification of the main volatiles produced under the torrefaction regime is useful for the optimization of the operating conditions of the integrated system. The integrated process raises some concerns when biomass from phytoremediation and wood from demolition and construction activities are used as feedstock because they could contain potential toxic elements (PTEs). During the torrefaction treatment, the fate of PTEs should be controlled to avoid their release in the gas phase and to evaluate the extent of their concentration in the torrefied biomass. The present work aims at studying torrefaction as an eco-sustainable process for the combined production of a solid biofuel with improved characteristics with respect to the starting material and a combustible vapor phase, embedded in the gas carrier flow, to be directly burned for energy recovery. Herein, torrefaction tests on Populus nigra L. branches from phytoremediation and demolition wood were conducted at three temperatures, 250, 270, and 300 °C, at a holding time of 15 min. The energetic content of torrefied materials was determined. At the same time, the fate of the heavy metals (Cd, Pb, and Zn) in the raw biomass at different torrefaction temperatures was studied, and their mobility in the torrefied biomass was investigated and compared to the mobility in the raw biomass.

更新日期：2018-06-13
• Energy Fuels (IF 3.091) Pub Date : 2018-06-12
Gaojian Ma, Lingmei Dai, Dehua Liu, Wei Du

Fish oil, containing quite a large amount of PUFAs (polyunsaturated free fatty acids, is well recognized as a good source for biodiesel and health care products production. A two-step process involving free lipase NS81006-mediated methanolysis followed by the immobilized lipase Novozym435-catalyzed methanolysis was proposed for the utilization of fish oil in this paper. During lipase NS81006-catalzyed methanolysis process, the selectivity of lipase on different FFAs (free fatty acids) was studied systematically and it was found that the length of carbon chain and the numbers as well as the position of C-C double bond had varied influence on the selectivity of lipase. The reaction rate and biodiesel yield decrease with the increase of carbon chain length; higher conversion could be obtained with unsaturated FFAs (C18:1, C18:2, C18:3) compared to unsaturated FFA (C18:0), and among which FFA with three double bonds gave the highest conversion. Through the this two-step lipase-mediated catalysis, both the common FFAs and PUFAs could be converted to its corresponding FAME (fatty acid methyl ester) effectively and a FAME yield of over 90% was obtained. The studies provide a rational guidance for biodiesel production as well as the enrichment of PUFAs.

更新日期：2018-06-13
• Energy Fuels (IF 3.091) Pub Date : 2018-06-12
Chunyan Zhang, Jingkai Zhao, Cheng Sun, Sujing Li, Dongxiao Zhang, Tianjiao Guo, Wei Li

ABSTRACT: A novel chemical absorption-biological reduction (CABR) integrated process, employing Fe(II)EDTA as an enhanced absorbent, is a promising technology for nitrogen oxides removal. In this work, we developed a new two-stage CABR system applying a mixed cultivation model of denitrifying bacteria and iron-reducing bacteria, which consists of a sieve-plate tower and a bioreduction tower to separate the absorption and reduction processes. The start-up period of the two-stage system was shortened into 19 days, while that of the one-stage CABR system was 46 days. In addition, the two-stage CABR system featured a better oxygen-resistance ability and a higher NO removal loading. As efforts to optimize system operation, we compare different modes of system operation, and found that: (1) continuous addition of glucose was better than the batch-type addition; (2) The NO removal efficiency can maintain >90% while FeEDTA concentration was higher than 4 mmol/L, but reducing the initial concentration of ferric iron complex could inhibit the loss rate of Na2EDTA. Furthermore, 4 mmol/L initial Fe(III)EDTA, 0.6 mg/min Na2EDTA and 5 mg/min glucose was the optimized operating mode with a 2 L/min gas flow rate under a 400 ppm NO condition, while the NO removal efficiency was kept >90%; the corresponding operating cost in terms of glucose was 8.4 g glucose/g NO. The purpose of this work was to provide preliminary data to support future industrial application for NOx removal, as well as sufficient technological insights on the process configuration and reactor operation of the two-stage CABR system.

更新日期：2018-06-13
Some contents have been Reproduced with permission of the American Chemical Society.
Some contents have been Reproduced by permission of The Royal Society of Chemistry.