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  • Potassium Ash Interactions with Oxygen Carriers Steel Converter Slag and Iron Mill Scale in Chemical-Looping Combustion of Biomass—Experimental Evaluation Using Model Compounds
    Energy Fuels (IF 3.021) Pub Date : 2020-01-21
    Felicia Störner; Fredrik Hildor; Henrik Leion; Maria Zevenhoven; Leena Hupa; Magnus Rydén

    Chemical-looping combustion (CLC) is a combustion technology in which a solid oxygen carrier is used to convert fuel. The oxygen carrier is oxidized in air and subsequently transferred to a separate reactor in which it reacts with the fuel. The produced CO2 is inherently separated from the air components, making CLC a promising technology for carbon capture and storage (CCS). CLC of biomass combined with CCS (bioenergy CCS; BECCS) is a way to generate negative CO2 emissions and thus interesting for climate change mitigation. Undesirable chemical reactions between ash and oxygen carriers are a challenge in BECCS because of the reactive nature of biomass ash. This article examines two low-cost steel industry byproducts that have shown desirable fuel conversion properties in CLC: iron mill scale (Glödskal B) and steel converter slag (LD-slag). Their interactions with potassium ash model compounds (KCl, K2CO3, K2SO4, and KH2PO4) in a reducing atmosphere have been investigated. Mixtures of oxygen carriers and potassium salt have been reduced for 6 h in CO and steam in a laboratory-scale fixed-bed reactor at 850 °C. The reduced samples have been analyzed with SEM/EDS and XRD. The reactivity of the mixtures during reduction and oxidation has also been examined by thermogravimetric analysis (TGA). K2CO3 increased the reaction rate for the reduction of Glödskal and inhibited the reactivity of LD-slag. KH2PO4 formed a K–P–Fe component with apparent low melting temperature with Glödskal, causing agglomeration, and decreased the reduction/oxidation rate in TGA. KH2PO4 formed a K–P–Ca component with apparent high melting temperature with LD-slag causing agglomeration but the reduction rate was not affected. The study suggests that the iron mill scale and LD-slag should not be rejected as oxygen carriers for CLC based on potassium ash interactions.

    更新日期:2020-01-22
  • Spinnable Mesophase Pitch Prepared via Co-carbonization of Fluid Catalytic Cracking Decant Oil and Synthetic Naphthalene Pitch
    Energy Fuels (IF 3.021) Pub Date : 2020-01-21
    Jianguang Guo; Hui Zhu; Huitao Xu; Aidan Westwood; Xuanke Li

    Using, as starting materials, fluid catalytic cracking decant oil (FDO), rich in short-chain alkyl groups, and synthetic naphthalene pitch (NP), with stable naphthenic structures, the synthesis of a spinnable mesophase pitch via a co-carbonization process was investigated. The effects of NP addition and the precursor molecular structure on properties of the resultant mesophase pitches and their carbon fiber derivatives were also discussed. With the increase of NP inclusion from 10 to 30 wt %, the solubility in toluene and quinoline and the optically anisotropic domain size of the synthesized pitches increase. However, the softening points of the resultant mesophase pitches decrease. In comparison to FDO, more naphthenic structures are retained in NP, and these show higher thermal stability during the preparation of mesophase pitch. The interaction of naphthenic structures in NP and short-chain alkyl groups in FDO promotes an increase in the molecular weight of the mesophase pitch prepared via co-carbonization and, in the present case, also increases the orientation and domain size in the resulting mesophase liquid crystal. The synthesized mesophase possesses a low softening point, good solubility, and 100 vol % mesophase content. Carbon fibers prepared from the co-carbonized mesophase pitch exhibit higher thermal conductivity than that of K-1100.

    更新日期:2020-01-22
  • Valorization of Vegetable Waste via Pyrolysis: Thermal Behavior, Volatiles Release, and Products Analysis from Its Extractives
    Energy Fuels (IF 3.021) Pub Date : 2020-01-21
    Yingyun Qiao; Fanfan Xu; Xue Ming; Shangwu Feng; Yaoyao Ji; Yuan Jiang; Jun Li; Bo Wang; Yuanyu Tian
    更新日期:2020-01-22
  • Hypergolic Ionic Liquid–Ethanol Mixtures for Lower Viscosity and Shorter Ignition Delay: Experimental and Molecular Dynamics Simulations
    Energy Fuels (IF 3.021) Pub Date : 2020-01-21
    Changgeng Sun; Shaokun Tang

    High viscosity and cost limit the performances and applications of hypergolic ionic liquids as propellant fuels. In this paper, several highly viscous hypergolic ionic liquids were prepared and mixed with low-cost ethanol in different proportions. These mixtures were tested by dropping them into an oxidizer, and their ignition delay time was obtained by a high-speed camera. The molecular dynamics simulations were applied to explore the microstructure and ionic interactions of mixtures. The results indicated that the viscosity was significantly reduced at a low mole fraction of ethanol (xethanol), and the maximum deviation was shown at xethanol = 0.3 for most ionic liquids. Molecular dynamics simulations suggested that ethanol destroyed and weakened original interactions between anions and cations and, therefore, enhanced their diffusivity and mobility in mixtures, which caused a significant decrease in viscosity. The ignition tests indicated that mixtures with a proper amount of ethanol usually showed a shorter ignition delay time than the pure ionic liquids, which confirmed the important role of viscosity on the ignition process. Our studies suggest that mixing with a proper amount of small-molecule liquid is a acceptable strategy for improving ionic mobility and ignition performances of hypergolic ionic liquids.

    更新日期:2020-01-22
  • Modeling and Optimization for Gas Distribution Patterns on Biomass Gasification Performance of Bubbling Spout Fluidized Bed
    Energy Fuels (IF 3.021) Pub Date : 2020-01-21
    Panxing Kang; Xiayi Eric Hu; Yujian Lu; Kuang Wang; Luchang Han; Haizhuan Yuan; Xiao Luo; Yefeng Jeffrey Zhou

    Gas distribution patterns exert a great impact on gas-solid flow, heat and mass transfer, reaction characteristics and thus affects significantly the thermal conversion efficiency inside the biomass gasifier. In this study, a 2-D biomass gasification model for bubbling spout fluidized-bed gasifiers (BSFBG) is established based on the kinetic theory of granular mixture (KTGM), and the prediction accuracy of the model is verified through a comparison between simulation values and experimental values. Furthermore, with the total mass flow rate of inlet gas set constant, the study has investigated how the ratio of inlet cross-sectional area to reactor area (Am/A) and the auxiliary gas velocity (Uf) affect the gas-solid flow, heat transfer and gasification performance in the BSFBG. As the results indicate, with Am/A increasing, the local particle flow structure becomes increasingly complex, particle volume fraction and temperature gets more evenly distributed, and the volume fraction of outlet key gas species (CO, H2 and CH4) as well as the lower heating value (LHV) is gradually rising. Besides, compared with the even gas distribution condition (Am/A=100%), the formation of overall and local counterclockwise particle circulation is facilitated by either a relatively high Uf with a low Am/A (≤50%), or a relatively low Uf with a high Am/A (≥75%). The circulation structure strengthens the gas-solid mixing in the pyrolysis zone and gasification zone in the middle-upper part of dense phase bed, which makes the volume fraction of outlet key gas species and LHV increase significantly. In the meanwhile, when Am/A =75% and Uf =1.0Umf, both the volume fraction and LHV reach the maximums, indicating the overall gasification performance achieves the optimal state. In conclusion, this study is of reference value for the investigation and intensification of gasification process, which helps to optimize BSFBG design and thus improve the biomass thermal conversion efficiency.

    更新日期:2020-01-22
  • Experimental and Kinetic Study on CaO-based CO2 Sorbent Pellets with Different Binders
    Energy Fuels (IF 3.021) Pub Date : 2020-01-21
    Yang Zhang; Xun Gong; Yang Peng; Erwei Leng; Yang Li; Xiaomin Li

    In this work, sorbent pellets were prepared based on six synthetic powdery sorbents. CO2 uptake tests and kinetic analysis were carried out to screen sorbent pellets. Experimental results showed that the CO2 capture capacity of sorbent pellets was lower than that of the powdery sorbents, which was mainly attributed to reduced BET specific surface area caused by pore structure damage during the pelletization process. However, the sorbent pellet CaSi75p containing 75 wt.% CaO and 25 wt.% Ca2SiO4 was less affected by pelletization than other sorbent pellets, which can be explained by formation of cracks and pores resulted from crystalline change of Ca2SiO4 during the calcination-carbonation cycles. Among all the sorbent pellets, CaSi75p showed the highest CO2 capture capacity of 0.531 g/g and 0.26 g/g in the first and 25th cycle. The performance of sorbent pellets was improved by adding cellulose as a pore-forming material. The reaction rate constants for all sorbents in each cycle were calculated. The experimental and kinetic data indicated that CaSi75p was an excellent sorbent even without adding cellulose.

    更新日期:2020-01-22
  • Technical Implications of Neglecting Compositional Grading Effects in Petroleum Reservoir simulation Models
    Energy Fuels (IF 3.021) Pub Date : 2020-01-21
    IKECHI IGWE; Jebraeel Gholinezhad; Mohamed G. Hassan Sayed; Frank Ogbuagu

    Most compositional reservoir simulation practices assumes that the compositions of various fluid components are the same at all locations within the reservoir system. This constant composition assumption is incorrect and unrealistic as it grossly ignores the occurrences of some less obvious physical processes in the reservoir. Gravitational force, temperature gradient and thermal diffusion, amongst other factors, contributes to distribution and gradation of hydrocarbon fluid compositions in the reservoir. Therefore, incorporating compositional grading models that adequately accounted for the individual and combined effects of gravity force, temperature gradient, and thermal diffusion is crucial when initializing reservoir simulation models. This research seeks to elucidate the technical implications of compositional grading on improved reserve estimation and reservoir performance prediction. The mathematical framework for the compositional grading modeling is based on one-dimensional zero-mass-flow stationary state assumption. The Computer Modelling Group’s equation of state multiphase equilibrium property simulator, WinProp, was used for the fluid modeling while Computer Modelling Group’s compositional reservoir simulator, GEM, was used for the reservoir modelling and simulation. In the absence of historical production data, Computer Modelling Group’s CMOST was used to perform uncertainty assessment for the validation of the initialized reservoir models. The research results show that initialized reservoir models that neglected or inadequately accounted for compositional grading effects, overestimated oil in-place and underestimated gas in-place. Constant composition (without compositional grading) initialized reservoir model overestimate ultimate cumulative oil production by 14.271 MMbbl more than the isothermal compositional grading model, and 24.088 MMbbl more than the Kempers thermal diffusion compositional grading initialized reservoir model. It underestimated ultimate cumulative gas production by 30.133 Bft3 less than the isothermal compositional grading, and 50.408 Bft3 less than the Kempers thermal diffusion compositional grading initialized reservoir model. These figures suggest that neglecting compositional grading or inadequate account of compositional grading effects in reservoir simulation initialization, has detrimental technical consequences.

    更新日期:2020-01-22
  • Fate of phosphorus in fluidized bed co-combustion of chicken litter with wheat straw and bark residues
    Energy Fuels (IF 3.021) Pub Date : 2020-01-21
    Gustav Häggström; Katharina Fürsatz; Matthias Kuba; Nils Skoglund; Marcus Öhman

    This study aims to determine the fate of P during fluidized bed co-combustion of chicken litter with K-rich fuels (e.g., wheat straw) and Ca-rich fuel (bark). The effect of fuel blending on phosphate speciation in the ash was investigated. This was performed by chemical characterization of ash fractions to determine which phosphate compounds that had formed and identify plausible ash transformation reactions for P. The ash fractions were produced in combustion experiments using chicken litter (CL) and fuel blends with 30% CL and wheat straw (WS) or bark (B) at 790-810 °C in a 5 kW laboratory-scale bubbling fluidized bed. Potassium feldspar was used as bed material. Bed ash particles, cyclone ash, and particulate matter (PM) were collected and subjected to chemical analysis with SEM-EDS and XRD. P was detected in coarse ash fractions only, i.e. the bed ash, cyclone ash, and coarse PM fraction (> 1 µm); no P could be detected in the fine PM fraction (< 1 µm). SEM-EDS analysis showed that P was mainly present in K-Ca-P-rich areas for pure CL as well as in in the ashes from fuel blends of CL with WS or B. In the WS blend, P was found together with Si in these areas. The crystalline compounds containing P was hydroxyapatite in all cases as well as whitlockite in the cases of pure CL and WS blend, of which the latter compound has been previously identified as a promising plant nutrient. Ash fractions from CL and bark blend only contained P in hydroxyapatite. Co-combustion of CL together with WS appears to be promising for P recovery and ashes with this composition could be further studied in plant growth experiments.

    更新日期:2020-01-22
  • Removal of NO by Using Sodium Persulfate Solution: Catalyzed by Different Nanostructured MnO2
    Energy Fuels (IF 3.021) Pub Date : 2020-01-21
    Yu-xuan Li; Rui-tang Guo; Zhong-yi Wang; Xu Shi; Wei-Guo Pan

    In this study, MnO2 nanotubes, nanowires, and nanoparticles were synthetized by a hydrothermal method, after which the NO removal process with sodium persulfate solution catalyzed by different-shaped MnO2 was studied and compared. It could be verified that MnO2 nanowires showed the best NO removal efficiency of 91.2% with the catalyst concentration of 0.06 mol/L. Illustrated from the XRD, SEM, TEM and XPS analysis results, the relatively higher activity of MnO2 nanowires could be attributed to its low crystallinity and the presence of more lattice oxygen. The reaction mechanism were further confirmed by using electron paramagnetic resonance (EPR) technique, which verified the promotional effect by capturing the signal of hydroxyl (·OH) and sulfate (SO4-·) radicals. Additionally, free radicals quenching experiments also verified the decisive impacts of these two radicals in the removal system, where sulfate (SO4-·) radicals played a major role.

    更新日期:2020-01-22
  • Ex-situ catalytic pyrolysis of algal biomass in a double microfixed-bed reactor: catalyst deactivation and its coking behavior
    Energy Fuels (IF 3.021) Pub Date : 2020-01-21
    Liangyuan Jia; Congcong Cao; Zhanjun Cheng; Jiahao Wang; Jiahui Huang; Jiuzhong Yang; Yang Pan; Minggao Xu; Yu Wang

    The catalytic fast pyrolysis (CFP) of algal biomass was conducted in a newly developed double microfixed-bed reactor (DFBR). Real-time measurements of catalytic vapors as a function of the cumulative biomass-to-catalyst ratio (BCR) could be achieved by mean of a single photoionization mass spectrometer (SPI-MS). The coked zeolites were characterized by various methods. During the catalytic conversion of algal biomass, products would tend to be classified into 3 different types based on their conversion (or formation) efficiency in CFP at the given BCR. More importantly, it was inferred that the “step-1”, which had been defined in the CFP of lignocellulosic biomass and would cause the catalyst coking, was lacked in the upgrading processes of algae-based pyrolysis vapors, probably due to the catalytic effect of minerals in algal biomass. This indicates a fact that algal biomass (especially for Sargasso) could be potentially an ideal feedstock to obtain valuable products via CFP. Furthermore, the mass per injection was proved to be an important factor to influence the accessibility of HZSM-5 catalyst due to the “traffic jam” when the primary volatiles enter the zeolite pores.

    更新日期:2020-01-22
  • Rational design of all-solid-state 0D/2D Mn0.2Cd0.8S/CeO2 direct Z-scheme for photocatalytic hydrogen evolution
    Energy Fuels (IF 3.021) Pub Date : 2020-01-21
    Yuanpeng Wang; Xuqiang Hao; Lijun Zhang; Yanbing Li; Zhiliang Jin

    Hydrogen production from photocatalytic water splitting has been considered as a promising way to convert solar energy into chemical energy. Herein, a novel photocatalyst was synthesized successfully by coupling two materials utilizing in-situ method. An all-solid-state 0D/2D contact direct Z-scheme heterojunction was constructed between Mn0.2Cd0.8S and CeO2, which formed an ideal photocatalytic system. It is proved that an efficient separation and enhanced redox ability of photoinduced charges can be obtained by constructing a direct Z-scheme composite photocatalyst. The maximum photocatalytic H2 generation rate of 8.73 mmol h−1 g−1 was obtained in the Na2S/Na2SO3 aqueous solution, which was 119 times greater than that of CeO2. The composition, microstructure, morphology, optical properties, behaviors of photoexcited electrons and electrochemical properties were studied utilizing a series of characterizations including XRD, SEM, TEM, mapping, Uv-vis, PL, photocurrent, etc. The results of XPS, XRD and SEM before and after the photocataytic hydrogen evolution indicated the composite is stable. Also, PL and photocurrent indicated the successful construction of direct Z-scheme. In addition, a Z-scheme mechanism for the photocatalytic hydrogen evolution was proposed and discussed. This work will provide new insights in designing and constructing novel Z-scheme heterojunction photocatalysts.

    更新日期:2020-01-22
  • Ultrafine Particle Formation in Pulverized Coal, Biomass, and Waste Combustion: Understanding the Relationship with Flame Synthesis Process
    Energy Fuels (IF 3.021) Pub Date : 2020-01-17
    Qian Huang; Peng Ma; Qi Gao; Shuiqing Li

    The adverse effect of ultrafine particulate matter (PM) from the combustion of solid fuels calls for fundamental insights to guide effective control strategies. In this work, we investigated the ultrafine PM formation from burning several solid fuel samples, with special emphasis on the relationship with an emerging field of flame synthesis. Diluted fly ash was sampled and characterized in a bench-scale flat-flame burner at the early stage (∼40 ms) and in a 25 kW quasi-one-dimensional combustor at the burnout stage (∼1.5 s). Then, the population balance model framework was transplanted from the community of flame aerosol synthesis to simulate the particle size distributions (PSDs). From the experiments, unimodal submicron PSDs were revealed for the combustion of coal, rice husk, and sewage sludge under 40 ms of residence time and a postflame ambience of 1500 K and 20 vol % O2. The compositional analysis reveals both the contributions from Na/K/P/S and from refractory species are important for ultrafine PM formation. This vaporization-nucleation mechanism highlights the similarity between solid fuel combustion and flame synthesis. However, the difference is raised by the medium and coarse mode PM that only appears in solid fuel combustion. The volatilized mineral and the ultrafine PM can be scavenged via coagulation, and the scavenged ratio takes ∼10–60% of the total volatilized minerals for different coal samples. This ratio is inversely correlated with the volatilized minerals on a basis of ash input.

    更新日期:2020-01-21
  • Understanding the Oxidation Behavior of Automotive Liquefied Petroleum Gas Fuels: Experimental and Kinetic Analyses
    Energy Fuels (IF 3.021) Pub Date : 2020-01-17
    Ajoy Kumar Ramalingam; Martin Krieck; Stefan Pischinger; Karl Alexander Heufer

    Liquefied petroleum gas (LPG) is a low-carbon fuel with an existing fuel supply infrastructure. As compared to petroleum-based gasoline, it features a higher octane rating. As compared to port fuel injection (PFI) systems, the direct injection (DI) of LPG engines reveals significant advantages in modern spark-ignition, such as higher efficiency. LPG primarily consists of C3 and C4 hydrocarbons, but the composition can drastically vary according to the current European LPG fuel standard EN 589. Several studies have focused already on understanding the oxidation process of its primary components. In this study, the focus will be on the autoignition behavior of different LPG compositions. Thereto, four different LPG fuels according to the current European LPG fuel standard EN 589 have been investigated. They cover a wide range of compositions and thus different autoignition behaviors. The fuels involve an LPG with a maximum propene/propane content, a typical winter-grade LPG with propane/n-butane/isobutane content, a high propane content, and high n-butane/isobutane content. These fuels also contain minor fragments of C2 and other C4 hydrocarbons. A rapid compression machine (RCM) has been used in this study to measure ignition delay times primarily in the low-to-intermediate temperature regime at stoichiometric conditions with a final compression pressure of 20 bar. Zero-dimensional simulations, including the facility effects of the RCM, have been performed with the help of detailed chemical kinetic mechanisms reported in the literature. The Aramco Mech 3.0 mechanism was chosen on the basis of its ability to represent the experimental data investigated in this study and additionally on the basis of the criteria that the major species in the mechanism are available and validated at application-relevant conditions. The mechanism is further used to understand the oxidation behavior of the fuel. Sensitivity analyses with the selected mechanism at application-relevant conditions were performed for the different LPG mixtures to reveal the most sensitive reactions, which affect the reactivity of the fuel. Similarly, to monitor the rate of production and consumption of species at experimental conditions of interest, flux analyses were performed at the point where 20% of the fuel is consumed. From the performed kinetic analyses, it is observed that the production of HȮ2 radicals by the subchemistry of the primary fuel component is consumed by propene subchemistry, leading to more ȮH radical production, which controls the global reactivity in the investigated regime.

    更新日期:2020-01-21
  • Compressibility of Supercritical Methane in Nanopores: a Molecular Simulations Study
    Energy Fuels (IF 3.021) Pub Date : 2020-01-20
    Nicholas Corrente; Christopher D. Dobrzanski; Gennady Y. Gor

    Unmineable coalbeds are a promising source of natural gas, and can act as a receptacle for CO2 sequestration. This is because they are composed of extensive nanoporous systems which allow for significant amounts of methane or CO2 to be trapped in the adsorbed state. The amount of fluid confined in the coal seams can be determined from seismic wave propagation using the Gassmann equation. However, in order to accurately apply the Gassmann theory to coalbed methane, the effects of confinement on methane in these nanoporous systems must be taken into account. In this work, we investigate these effects of confinement on supercritical methane in model carbon nanopores. Using Monte Carlo and molecular dynamics simulations, we calculated the isothermal elastic modulus of confined methane. We showed that the effects of confinement on the elastic modulus of supercritical methane are similar to the effects on subcritical fluids: (1) the elastic modulus of confined fluid is higher than in bulk; (2) for a given pore size, the modulus monotonically increases with pressure; and (3) at a given pressure, the modulus monotonically increases with the reciprocal pore size. However, these effects appeared much more pronounced than for subcritical fluids, showing up to seven-fold increases of the modulus in 2 nm pores. Such significant increase should be taken into account when predicting the wave propagation in methane-saturated porous media.

    更新日期:2020-01-21
  • The interaction of NH4HSO4 with Vanadium-Titanium Catalyst Modified by Molybdenum and Tungsten
    Energy Fuels (IF 3.021) Pub Date : 2020-01-20
    Jie Yu; esong zhang; lele wang; Zijian Song; fanhai kong; yunlong ma; Hong Zhao; Lushi Sun

    With the wide application of SCR (selective catalytic reduction) system in power plant for the control of NOx emission in China, serious problem of catalyst deactivation by blockage of NH4HSO4 (ABS) has drawn extensive attention. In this paper, a combined of experimental and simulation method was utilized to study the interaction between NH4HSO4 and vanadium-titanium-based catalyst. The results revealed that NH4HSO4 was thermally dissociated into NH4+ and SO42- on TiO2, with the electrons of S and Ti atom drawn to oxygen atoms in SO42-. The introduction of V2O5, WO3 and MoO3 can form a protective layer to inhibit the adsorption of NH4HSO4 onto TiO2, reduce the electron transfer of S atom, and promote the reaction of NH4+ with NO. The thermogravimetric analysis also revealed that the electron transfer of S atom inhibited the reduction of SO42- to SO2. On V-5Mo/TiO2 catalyst, about 78% of NH4+ in NH4HSO4 were attached onto Lewis acid site, which accelerated the reduction reaction of NO by NH4+, while the electron density of S atom in SO42- kept almost unchanged, thus SO42- can be comparatively easily decomposed at lower temperatures. The fixed bed experiments were conducted to compare the activities of studied catalysts and the effect of NH4HSO4 on their activities. It was proved that V-5Mo/TiO2 catalyst loaded with NH4HSO4 showed a better performance at low temperatures.

    更新日期:2020-01-21
  • Properties of Nano-fluids and Their Applications in Enhanced Oil Recovery: a Comprehensive Review
    Energy Fuels (IF 3.021) Pub Date : 2020-01-19
    Yongxiang Sun; donghai yang; Leicheng Shi; Huanyu Wu; Yun Cao; Yiming He; Tengteng Xie

    Nano-fluids are stable mixtures of nanoscale particles dispersed in base fluids with good prospects in Enhanced Oil Recovery (EOR) in the petroleum industry. In this review, the mechanisms and evaluation methods of stable nano-fluids were analyzed. The effects of nanoparticles on viscosity, electrical conductivity and surface/interfacial tension of base fluids were discussed. The results of laboratory research and field tests revealed that nano-fluids could improve the oil recovery through plugging and profile control, transformation of wettability of rock surface, change in oil–water interface properties and increase in viscosity ratio between fluids. On the other hand, nanoparticles might stabilize oil–water emulsions produced during the extraction stage, adversely affecting subsequent oil–water separation processes, especially the electrical dehydration. However, careful analysis suggested lack of in-depth studies regarding the impacts of nanoparticles on droplet coalescence inside electro-dehydration plants. The present analyses would hopefully assist future investigations in nano-fluidics.

    更新日期:2020-01-21
  • A novel polyether for efficient demulsification of interfacially active asphaltenes stabilized water-in-oil emulsions
    Energy Fuels (IF 3.021) Pub Date : 2020-01-19
    Xingang Li; Jun Ma; Renzhou Bian; Jing Cheng; Hong Sui; Lin He

    The interfacially active asphaltenes (IAA, 1.75wt% of the total asphaltenes) from the Indonesian asphalt rocks have been proved to be the major component in stabilizing the water-in-oil (W/O) emulsion (stable even over 1 year) than other fractions in asphalt (i.e., asphaltenes, maltenes (asphalt without asphaltenes), remaining asphaltenes (RA, asphaltenes without IAA)). The droplet size of the IAA-stabilized emulsion was determined to be in the range from 10 um to 20 um. To demulsify this extremely stable emulsion, we synthesized a novel polyether demulsifier (JMNP) with rich oxygen by simple esterification and polymerization. When applying the JMNP and commercial demulsifiers (polyethylene glycol (PEG8000), SP169, PE1951 and AP2050) in breaking this emulsions. Results showed that although all of them could demulsify the IAA-stabilized emulsions, the JMNP performs well in enhancing the demulsification of the IAA-stabilized emulsion, achieving complete dehydration of the emulsions in 30 min at 60 ℃ and 400 ppm. The types and number of the oxygen-containing groups (hydroxyl, ester group, polyethylene oxide segment, polypropylene oxide segment) in the demulsifiers are considered to play the key role in breaking of the IAA film and finally the coalescence of the water droplets. This primary test suggested that the JMNP would be potential candidate for the demulsification of water-in-heavy oil emulsions. Keywords: Interfacially active asphaltenes; Emulsions; Stability; Polyether; Demulsification

    更新日期:2020-01-21
  • Supercritical pyrolysis and coking of JP-10 in regenerative cooling channels
    Energy Fuels (IF 3.021) Pub Date : 2020-01-19
    Yu Pan; Haocui Zhang; Chunyu Zhang; Hongyan Wang; Kai Jing; Limin Wang; Xiangwen Zhang; Guozhu Liu

    JP-10 is a potential endothermic hydrocarbon fuel (EHF) with high energy density for the regenerative cooling technology of advanced aircrafts. In this work, pyrolysis and coking of JP-10 was experimentally studied using an electrically heated tube as a flowing reactor under the supercritical conditions (4.5 MPa, 550-735 oC). For the supercritical pyrolysis, dicyclopentadiene, exo-TCD4e and indane/indene was observed with relatively higher selectivity at low conversion, and the selectivities of typical products (ethene, propene, CPD, cyclopentene and benzene) were lower compared with that under atmosphere pressure, possible because of the enhanced bimolecular reactions. The heat sink of JP-10 was ca. 2.5 MJ/kg ascribed to the severe coke formation during the pyrolysis. Further characterizations on cokes indicated that the coke in the bulk fluid was about 70-170 times higher than that deposited on the wall, attributed to rapid formation of ploycyclic aromatic hydrocarbons (PAHs) of pyrolysis products rather than the wall catalysis.

    更新日期:2020-01-21
  • Cobalt carbide from Co-Mn layered double hydroxide: highly efficient catalyst for toluene pyrolysis
    Energy Fuels (IF 3.021) Pub Date : 2020-01-19
    Chunhao Wang; Xiang Xu; Yang Guo; Fan Zhou; Hongyu Chen; Haoyang Li; Zheng Zeng; Liqing Li

    The cobalt carbide (Co2C) innovatively prepared from Co-Mn layered double hydroxide (CoMn LDH) has been investigated and evaluated toward its alternative synthesis conditions and different catalytic performances. Along with various characterization techniques, the preparation basically contains four steps (synthesis of CoMn LDH, calcination, reduction and crystallization) that transforms CoMn LDH to CoMn spinel, then to Co2C. Catalyst evaluation toward toluene pyrolysis was conducted. The sample with Co2C exhibited almost 100 % conversion rate of toluene, where the resulting hydrogen yield (~ 1.8 %) is 6 times more than that of the blank test by using silica sand (~ 0.3 %), realizing the full transfer of hydrogen element from toluene to hydrogen molecule. Furthermore, based on the textural analysis and DFT-D calculation, which theoretically explained the easy accessibility of toluene to the crystal surface of Co2C (001) with a relatively high adsorption energy (about −280 kJ mol−1), it suggested that Co2C may expand more extensive applications in the field of catalyst.

    更新日期:2020-01-21
  • Limestone Attrition and Product Layer Development During Fluidized-Bed Sulfation
    Energy Fuels (IF 3.021) Pub Date : 2020-01-19
    Dongfang Li; Man Zhang; Minwoo Kim; Runxia Cai; Hairui Yang; Kyeong Choi; Seokgi Ahn; Chung-Hwan Jeon

    Limestone is widely used as a sorbent in fluidized bed combustors. The study of limestone attrition characteristics is significant for mass balance and desulfurization efficiency. The present study investigates the sulfation and attrition behavior of limestone in a bubbling fluidized bed reactor. The product distribution and the development of the product layer are analyzed by scanning electron microscopy. The experimental results show the attrition rate dropped dramatically at the initial kinetic-controlled regime of the sulfation reaction. The observations show the distribution of the product is not uniform, but primarily concentrated on the external surface of the particle. Meanwhile, the thickness of the product layer at the initial stage of the sulfation reaction reaches 0.7 μm, which is larger than that predicted by previous investigators, and it results in a dramatic decrease in the attrition rate. As sulfation continues, the thickness of the product layer increases and reaches 1.6 μm at the diffusion-controlled regime of the reaction, whereas the attrition rate decays to a steady state. A random pore model (RPM) is also used to analyze the development of the product layer thickness by counting in the whole reaction surface, but the results show much smaller value due to the lack of consideration of the unreacted core, which verifies the early pore blockage in the initial stage observed in the present study.

    更新日期:2020-01-21
  • Rheological behavior of heavy and extra-heavy crude oils at high pressure
    Energy Fuels (IF 3.021) Pub Date : 2020-01-17
    Patsy Verónica Ramírez-González; Sergio E. Ernando Quiñones-Cisneros

    The processing, production, and transport of heavy crude oils are big challenges for the petroleum industry. Central to this challenge is the fluid viscosity: the key variable responsible for the oil fluidity throughout the entire production process. From the reservoir to delivery conditions, oils undergo large variations in temperature and pressure, which may cause important phase behavior and physico-chemical changes, directly affecting the fluid thermophysical properties. In the case of heavy oils, such a broad change of conditions categorically results in several orders of magnitude viscosity-span, including possible Newtonian to non-Newtonian rheological behavior transitions. It is, therefore, of primary importance that heavy oils be rheologically well-characterized to ensure their production process success and viability. The viscosity of heavy and extra-heavy crude oils at extreme conditions (high pressure, high to low temperature, high to low shear-rate) is, however, difficult to fully directly measure for most service laboratories. Several lapses may occur when measuring the full range of required conditions with traditional rheometers; for example, for such viscous fluids, the development of laminar-flow structural anomalies (eddies) and magnetic decoupling in the high-pressure cell are common practical problems. In an attempt to pragmatically address these problems, in this work, a methodology that may allow for the rheological characterization of heavy and extra-heavy oils within the full field operational range but based on limited laboratory measurements is proposed. The proposed approach does not follow from a simple extrapolation but it is rather derived from the concept of control-variable shifting. For achieving this, the superposition principle is applied to shear-temperature and shear-pressure reliable measurements to construct master curves able to rheologically characterize the fluid within conditions that may be too severe for direct laboratory measurements. This methodology has been successfully applied to a database of twenty Mexican fluids, going from extra-heavy to light fluids. The rheology of the samples were originally studied using three different types of equipment: 1) a strain-controlled rheometer (for the measurement of the fluid rheology at ambient pressure and different temperatures) 2) a sliding piston viscometer for high-pressure and low shear-rate viscosity measurements and 3) a hybrid rheometer coupled with a pressure cell for the estimation of the fluids rheological behavior under pressure and high shear-rate. The rheological behavior of crude oils could then be obtained at conditions as severe as the equipment allowed (up to 1000 bar and, in some cases, shear-rate up to 1000 s-1. The master curves allowed, however, to extend the rheological characterization of the fluids within conditions that were beyond the laboratory capabilities.

    更新日期:2020-01-21
  • A New Detailed Ethanol Kinetic Mechanism at Engine-Relevant Conditions
    Energy Fuels (IF 3.021) Pub Date : 2020-01-17
    Shrabanti Roy; Omid Askari

    Ethanol is considered one of the most attractive renewable energy sources in the modern days. A chemical mechanism on ethanol is generated in this work to predict the performance of this fuel in engine relevant operating conditions. To build this mechanism, a reaction mechanism generator (RMG) is utilized. The generated mechanism is compared against experimental results to find its accuracy. Important reactions responsible for the results are selected through sensitivity and path flux analysis. Rate parameter of important reactions is further adjusted from available literature data. The final mechanism is named PCRL-Mech1 and consists of 67 species and 1016 reactions. This mechanism shows an excellent agreement with experimental results of laminar burning speed and ignition delay time (using shock tube and rapid compression machine). The mechanism is validated at temperatures, pressures and equivalence ratios of 300-650 K, 1-10 atm and 0.6-1.4 for laminar burning speed. For ignition delay time verification, temperatures of 820-1450 K, pressures of 3.3-80 atm, and equivalence ratios of 0.3-2 are considered. The new-developed mechanism is also validated for species concentration through a flow reactor, a jet stirred reactor and a partially premixed counter flow flame. Finally, the PCRL-Mech1 mechanism is compared with six-top mechanisms available in literature. A normalized ratio of accuracy and computational time for other mechanisms with respect to PCRL-Mech1 is generated. It is found that PCRL-Mech1 has better combination of accuracy and time throughout all the varied operating conditions.

    更新日期:2020-01-21
  • Preparation and characterization of coal pitch based needle coke (PartⅡ): The effects of β resin in refined coal pitch
    Energy Fuels (IF 3.021) Pub Date : 2020-01-17
    Yaming Zhu; Hu Chaoshuai; Xu Yunliang; Zhao Chunlei; Xitao Yin; Zhao Xuefei

    Refined coal pitch is a promising precursor to produce high-quality needle coke with its excellent physical-chemical properties. It was generally accepted that, the basic properties of refined coal pitch kept a key role on the quality of the derived needle coke during the delayed coking process. Our previous research showed that, refined coal pitch with fa of 0.95~0.98 was the perfectible precursor to produce high-quality needle coke. What’s more, we found the contents of β resin in refined pitch were also important to the properties (micro-structure, micro-strength, and true density) of the derived needle coke. In order to a detailed study of the affects of the contents of β resin on the properties of needle coke, 8 types of refined coal pitch (the fa range from 0.9621 to 0.9725) with varied contents of β resin were used as the raw materials to produce needle coke. Briefly, 1H-NMR and Gel permeation chromatography (GPC) were used to determine the fa and molecular weight of each refined coal pitch, respectively. Micro-structures (optical micro-structure and surface morphology) have been analyzed by polarizing microscope and scanning electron microscopy, separately. XRD, Raman spectrum, and curve-fitted methods have been used to quantitative examination microcrystalline structure. What’s more, micro-strength and true density of each needle coke have been also examined in this study. The results have shown that, the refined coal pitch with the contents of β resin of 13%~16% were the excellent precursors to produce high quality needle coke.

    更新日期:2020-01-21
  • Simulating the geological fate of terrestrial organic matter: Lignin vs Cellulose
    Energy Fuels (IF 3.021) Pub Date : 2020-01-17
    Lea Atmani; Pierre-Louis Valdenaire; Roland J.-M. Pellenq; Christophe Bichara; Henri Van Damme; Adri C.T. van Duin; Franz-Josef Ulm; Jean-Marc Leyssale

    While shale gas has become a major source of energy, a more sustainable recovery requires better understanding of the gas/kerogen matrix interactions. Here we use replica exchange molecular dynamics to investigate the geological conversion of two important classes of gas-forming organic matter: lignin and cellulose. In agreement with results from pyrolysis experiments, we show that lignin produces twice as much kerogen and five times more methane than cellulose. In addition, while ex-cellulose kerogen is relatively stiff and almost non porous, ex-lignin kerogen, despite having very similar composition and bonding, is an order of magnitude more compliant due to the presence of large micropores. The obtained results can potentially improve the nanoscale brick of bottom-up models of shale gas recovery.

    更新日期:2020-01-21
  • Asymmetric Probability Distribution Function-Based Distillation Curve Reconstruction and Feature Extraction for Industrial Oil-Refining Processes
    Energy Fuels (IF 3.021) Pub Date : 2020-01-17
    Yongfei Xue; Yalin Wang; Bei Sun

    A distillation curve is an essential property for petroleum. Its features are beneficial for the modeling and optimization of oil-refining processes. To capture these features with a small number of parameters, an asymmetric probability distribution function-based distillation curve reconstruction and feature extraction method is proposed for the industrial oil-refining process. In our research, the expressive power of several frequently used probability distribution functions are first tested with some available distillation data. According to the statistics, the Kumaraswamy distribution function, one of the asymmetric probability distribution functions with four parameters, is identified as the best. Because not all distillation data are directly obtainable in the industry, the total probability theory-based data synthesis technique is adopted to estimate the key distillation points of unsampled streams, especially for the unmeasurable intermediate products at the outlet of a reaction system. Along with the distillation curve reconstruction, features of the synthetic distillation data are extracted by optimizing the parameters of the Kumaraswamy distribution function using the state transition algorithm. Industrial experiments were carried out to demonstrate the effectiveness of our proposal.

    更新日期:2020-01-17
  • Study on the Co-gasification Reactivity and Interaction Mechanism of Coal with Different Components of Daily Food Waste
    Energy Fuels (IF 3.021) Pub Date : 2020-01-16
    Xiaopeng Zou; Lu Ding; Xin Gong

    Food waste is a global challenge for the environment but also an available fuel with complex components. In this paper, rice, lettuce, and fish residue (contained meat and bone) were selected as typical components of daily food waste. The co-gasification reactivity of three food wastes with Shenfu coal was tested via thermogravimetric analysis. The interaction mechanism was further studied via scanning electron microscopy–energy-dispersive X-ray spectroscopy, heating stage microscope, and Fourier transform (FT)-Raman techniques. The lettuce/fish waste char presented great synergy with coal char during co-gasification, whereas no synergy was observed during co-gasification of rice char and coal char. During co-gasification of lettuce/fish waste char and coal char, the ash from lettuce (rich in potassium) and fish residue (rich in calcium) migrated to the surface of coal char and further catalyzed the coal char gasification. The synergetic effect was further confirmed via a high-temperature stage microscope. In addition, The FT-Raman analysis showed that the lettuce and fish ash increased the reacting sites of Shenfu char and inhibited the degree of graphitization.

    更新日期:2020-01-17
  • Influence of Wax on Cyclopentane Clathrate Hydrate Cohesive Forces and Interfacial Properties
    Energy Fuels (IF 3.021) Pub Date : 2020-01-16
    Wei Wang; Qiyu Huang; Sijia Hu; Peng Zhang; Carolyn A. Koh
    更新日期:2020-01-17
  • Design Modification of Acid Gas Cleaning Units for an Enhanced Performance in Natural Gas Processing
    Energy Fuels (IF 3.021) Pub Date : 2020-01-16
    Amr Al-Amri; Umer Zahid

    Acid gas cleaning is one of the natural gas processing steps where the acid gases are removed to satisfy the quality of the sweet gas. Conventionally, this is achieved by processing the sour gas through an acid gas removal (AGR) unit to produce the desired sweet gas while concentrating the H2S gas in the acid gas enrichment unit. Together with achieving the required high heating value of 930 BTU/SCF in the sweet gas, it is also desired from the process that the acid gases must contain 30–55% H2S content before feeding to the sulfur recovery unit. In addition, the waste gases sent to the thermal oxidizer must not contain more than 2000 ppmv H2S. However, these requirements put a constraint on the process operational flexibility especially when the feed gas has a high CO2 content. In this study, a novel acid gas cleaning design has been proposed that can significantly reduce the energy requirement while maintaining all the streams’ design specifications. The proposed design recommends first producing acid gas with the required purity and then producing the sweet gas in another AGR unit. The results show that the proposed design requires 22% lower operational energy compared to the base design. The economic analysis reflects a saving of more than $7.25 million in total annual cost compared to the conventional design.

    更新日期:2020-01-17
  • Chemical Looping Reforming of Glycerol for Continuous H2 Production by Moving-Bed Reactors: Simulation and Experiment
    Energy Fuels (IF 3.021) Pub Date : 2020-01-16
    Bo Jiang; Lin Li; Qian Zhang; Jing Ma; Haotian Zhang; Jun Bai; Zhoufeng Bian; Binlin Dou; Sibudjing Kawi; Dawei Tang

    Chemical looping reforming of biomass is a promising avenue for hydrogen generation. Both the design of reactor configurations and the screening of oxygen carriers represent major challenges in chemical looping technologies. Here, we synthesize three oxygen carriers (referred to as Ni–Al, NiW–Al, and W–Al) by a continuous coprecipitation method and first test them in a fixed-bed reactor. The NiW–Al showed the highest coke resistance, reducibility, and glycerol conversion. We employ an Ellingham diagram to explain the superior performance of the NiW–Al and screen operational temperatures from the standpoint of thermodynamics. Then, using the NiW–Al oxygen carriers, we investigate the effect of Ni-to-glycerol ratio, fuel reactor temperature, and steam-to-glycerol ratio in moving-bed reactors. Establishing two sets of five-stage equilibrium models in Aspen Plus, we compare the experimental results with simulations, discovering good agreement with each other. An isothermal and coke-free operational window was optimized at a fuel reactor temperature of 650 °C, a Ni-to-glycerol ratio of 0.9, and a steam-to-glycerol ratio of 4.5, achieving an average H2 yield of 1.5 mol-H2/mol-C. This work highlights the promise of combining moving-bed reactors with oxygen carriers with high oxygen storage capacity to utilize biomass by chemical looping reforming for continuous H2 generation.

    更新日期:2020-01-17
  • Effect of Geological Depths on CH4 Adsorption, Diffusion, and Swelling in Kaolinite by Molecular Simulations
    Energy Fuels (IF 3.021) Pub Date : 2020-01-16
    Kai Wang; Bin Zhang; Tianhe Kang

    The demand for energy in the world has increased dramatically, leading to an increase in the geological depth of unconventional natural gas development such as shale gas. Comprehension adsorption and diffusion of CH4 at different geological depths is extremely significant, especially in the case of large depths. In this study, the molecular simulations were utilized to investigate the CH4 adsorption, diffusion, and swelling in kaolinite up to 6 km. The outcomes show that the adsorption amount of CH4 on kaolinite increases to the maximum at 2 MPa, while it decreases with increasing geological depth. This phenomenon is explained by the total interaction energy and adsorption isosteric heat between CH4 and kaolinite. The hydrogen and oxygen atoms in kaolinite molecules are the strongly adsorbed sites of CH4. Because of the wall effect, two strong adsorption layers of CH4 molecules were formed adjacent to the kaolinite surface. The CH4 coefficient, including that of self-diffusion and Fick diffusion, increased linearly with the geological depth, and the CH4 diffusion activation energy in kaolinite is about 1.61 kJ/mol at 1–6 km. The kaolinite volume increases first, then slightly decreases, and finally obviously increases with increasing geological depth. By considering the results of adsorption, diffusion, and expansion, we infer that the optimal kaolinite-bearing shale gas reservoir is buried at a depth of 3–4 km.

    更新日期:2020-01-17
  • Salt-Responsive Zwitterionic Polymer Brush Based on Modified Silica Nanoparticles as a Fluid-Loss Additive in Water-Based Drilling Fluids
    Energy Fuels (IF 3.021) Pub Date : 2020-01-16
    Jinsheng Sun; Xiaofeng Chang; Fan Zhang; Yingrui Bai; Kaihe Lv; Jintang Wang; Xinyu Zhou; Bo Wang

    Wellbore instability and formation collapse are crucial issues in the process of well excavation in the oil industry under extreme salinity and high-temperature conditions. This study demonstrates that a salt-responsive zwitterionic polymer brush (NS-DAD) based on modified nanosilica as a fluid-loss additive utilizing the anti-polyelectrolyte effect in water-based drilling fluids (WDFs) to overcome the wellbore instability caused by the failure of polyelectrolytes at extreme salinity and high temperature. Additionally, a nonionic polymer brush (NS-D), an anionic polymer brush (NS-DA), and a cationic brush (NS-DD) were also prepared for comparison. Compared with NS-D, NS-DA, and NS-DD, NS-DAD exhibited the anti-polyelectrolyte phenomenon, in which the sodium chloride electrolyte shields the electrostatic interaction in the molecular chain of the polyzwitterion and the molecular structure changes from a collapsed sphere to a more open helix. Macroscopically, NS-DAD exhibited a higher viscosity than NS-D, NS-DA, and NS-DD in saturated salt-based mud (SSBM). A typical “star-net” structure was observed between NS-DAD and the bentonite layer. Energy-dispersive spectroscopy (EDS) analysis of filter cakes showed that NS-DAD could significantly reduce the content of chloride and sodium ions in the bentonite layer. Therefore, compared with NS-D/SSBM, NS-DA/SSBM, and NS-DD/SSBM, NS-DAD/SSBM had excellent rheological properties, thermal stability, less fluid-loss volume, and thinner filter cake under extreme salinity and high-temperature conditions. The fluid-loss additive can be used to reduce the fluid-loss volume of WDFs in harsh reservoir conditions of high temperature and high salinity.

    更新日期:2020-01-17
  • Efficient catalytic conversion of waste peanut shells into liquid biofuel: an artificial intelligence approach
    Energy Fuels (IF 3.021) Pub Date : 2020-01-17
    Pan Li; Zeji Du; Chun Chang; Shiqiang Zhao; Guizhuan Xu; Chunbao (Charles) Xu

    Artificial intelligence approach can be used to solve complicated process problems. A hybrid methodology comprising artificial neural network (ANN) and genetic algorithms (GA) was utilized to model and optimize the methanolysis process of waste peanut shells. Acid catalytic methanolysis of waste peanut shells into liquid biofuel-methyl levulinate (ML) was investigated. The combination of sulfuric acid with extremely low concentration and Al2(SO4)3 was identified as the efficient mixed acid catalytic system. The ML yield under the optimal conditions optimized by response surface methodology (RSM) was 16.49%, while the ML yield optimized by ANN-GA was 17.61%.The results showed that the ANN-GA had a higher optimizing ability than that of RSM model. Meanwhile, the methanolysis kinetics provided the insights into the reaction routes for the ML production. Moreover, Al2(SO4)3 can be recycled and reused five times without much decrease of the ML yield. This study suggested that the waste peanut shells can be used as the potential raw materials for the ML production, and the ANN-GA can serve as a powerful tool for the biofuel processing technology.

    更新日期:2020-01-17
  • Deformation of Shale and Coal Organic Carbon Slit Micropores Induced by CO2 Enhanced Gas Recovery: A Monte Carlo Simulation Study
    Energy Fuels (IF 3.021) Pub Date : 2020-01-17
    Hongyang Zhang; Rui Diao; Hing Hao Chan; Masood Mostofi; Brian Evans

    The swelling of shale and coal induced by the CO2 enhanced gas recovery (CO2-EGR) has proved to reduce the reservoir permeability and the CH4 production. In this work, we have studied the adsorption-induced deformation of the organic carbon slit micropores during the displacement of CH4 by the injected CO2 using grand canonical Monte Carlo simulation. Particularly, we have investigated the effect of the injected CO2 ratio on the deformation strain for each pore width from 0.5 nm to 2.0 nm under a series of pressures and temperatures. The results showed that the pore deformation is distinct depending on the pore size and the injected CO2 ratio, which generally includes monotonic swelling and shrinkage followed by swelling with bulk pressure. The pores below 0.55 nm have no deformation, as these pores are too narrow for both CH4 and CO2. The maximum swelling in CO2-EGR occurs in the 0.55-0.59 nm pores, which contributes most in terms of the CO2 storage, but has no contribution to CH4 recovery. The maximum shrinkage happens in the 0.66 nm pore, which provides most to the CH4 recovery. Besides, the maximum swelling and shrinkage is generally not affected by the CO2 ratio except the deformation at low pressures, and even a small amount of CO2 injection could induce the maximum swelling for the corresponding pores in shale or coal. The bulk pressure has a more significant effect on the deformation of the 0.75-1.05 nm pores with the increase of CO2 ratio, and the pore width for the maximum swelling decreases with the increase of pressure. At 100 MPa, a second minor peak of swelling and shrinkage occurs in the 0.85-0.9 nm and 0.95-1.05 nm pores respectively. Furthermore, temperature has no effect on the maximum swelling at 100 MPa, but the overall deformation generally decreases with the increase of temperature including the maximum shrinkage. The 1.4-2.0 nm pores only have slight deformation regardless of the CO2 ratio, pressure and temperature. It is also found that the solvation pressure is the driving force for the deformation irrespective of the adsorbed gas species. However, the adsorbed CH4 and CO2 molecules exert different solvation pressures to the pores during the competitive adsorption. The local solvation pressure is heterogeneous across the pore space for both CH4 and CO2. The positive pressures are close to the pore walls which tend to swell the pores, but negative pressures are in the pore interior, which incline to contract the pore.

    更新日期:2020-01-17
  • Visual Experimental Analysis on the Residence Time of Flexible Biomass Particles in a Baffled-Rotating Cylindrical Tube
    Energy Fuels (IF 3.021) Pub Date : 2020-01-17
    Conghui Gu; Yujian Zhang; Danping Pan; Shouguang Yao; Kotkin Vladimir; Lei Guan; Kai Wu; Zhulin Yuan

    The drying of biomass or biofuels is a major issue during pretreatment because of high initial moisture content, which results in low energy efficiency, combustion temperature and high emission of hydrocarbons. As the motion behaviors of biomass fuels play an important role in the drying process, it is of great significance to investigate the motion of biomass. In this paper, visualization experiments on the motion of flexible non-spherical biomass particles in a baffled rotating cylindrical tube were performed. The residence time of biomass particles was obtained and analyzed by taking into account, gas velocity, mass flow rate of flexible biomass, initial moisture content of biomass particles, slope and rotational speed of the cylindrical tube and other parameters under several operational conditions. The results indicated that the mean residence time of flexible biomass increased with the increase of mass flow rate and initial moisture content, and decreased with the increase of the cylindrical tube’s rotational speed and slope, and the velocity of the gas phase. Despite of quite small sliding friction coefficient between the tube’s inner wall and biomass particles, larger slope could lead to stronger the sliding friction force in the axial direction when these biomass particles moved to the bottom of the tube. Mean residence time is observed to decrease significantly and gradually decrease with the increase of rotational speed from 6 r/min to 9 r/min, and from 9 r/min to 18 r/min, respectively. In addition, mean residence time increased from 78.5s to 99.4s when the inlet mass flow rate increased from 60 kg/h to 240 kg/h without gas phase, but it increased from 57.4s to 78.5s within the same range of inlet mass flow rate at the gas velocity of 0.3 m/s.

    更新日期:2020-01-17
  • Evaluation of Asphaltene Adsorption Free Energy at the Oil−Water Interface: Role of Heteroatoms
    Energy Fuels (IF 3.021) Pub Date : 2020-01-17
    Jo Mizuhara; Yunfeng Liang; Yoshihiro Masuda; Kazuya Kobayashi; Hiroki Iwama; Hideharu Yonebayashi

    In this study, we investigated the stability of asphaltene adsorption structures at the oil−water interface, focusing on the role of heteroatoms, by molecular dynamics simulations. We employed oil (1:1 mixture of heptane and toluene, by volume)-water system and used thirteen types of asphaltene molecules. Two sets of asphaltene models with the alkyl side chain at different locations were considered. For each set, six models were employed, which have essentially the same structures but with different heteroatoms (such as nitrogen, oxygen, and sulfur) on the aromatic ring (i.e. heteroaromatic ring). Besides twelve models, an additional asphaltene molecule with carboxyl group at the end of the alkyl side chain was included. We evaluated the asphaltene adsorption Gibbs free energy at the oil−water interface using potential of mean force calculations. It is found that the basic pyridine-type nitrogen-containing asphaltene presents the highest adsorption Gibbs free energy among six asphaltene molecules for both sets. The heteroatom of asphaltene molecule forms hydrogen bond with the water molecules so that it can stabilize asphaltene adsorption at the oil−water interface. The strength of the hydrogen bond depends on the negative charge of the heteroatom, with basic pyridine-type nitrogen being the highest, and the highest adsorption Gibbs free energy. Furthermore, it is found that the acidic pyrrole-type nitrogen-containing asphaltene has the most significant weak hydrogen bonding between the heteroaromatic ring and water molecules due to the charge of carbon atom in that ring being higher than others. The thiophene-type sulfur-containing asphaltene has the most significant van der Waals interaction, the adsorption Gibbs free energy shows a significant value for both sets. The carboxyl asphaltene molecule has the highest affinity to the oil−water interface among thirteen models because it has two heteroatoms. The detailed understanding of the asphaltene adsorption behavior presented in this study would be useful to solve the stability issue of oil−water emulsions in crude oil production.

    更新日期:2020-01-17
  • Synergistic effects of furfural and sulfuric acid on the decomposition of levulinic acid
    Energy Fuels (IF 3.021) Pub Date : 2020-01-17
    Wenbing Chen; Hanwen Hu; Qinjie Cai; Suping Zhang

    Decomposition of levulinic acid (LA) is a critical factor limiting the yield of LA produced by biomass hydrolysis. In this study, effect of influencing factors, especially furfural, on the decomposition of LA were investigated. Results show that furfural, as the hemicellulose hydrolysis product, led to an increase on LA decomposition, 25.3% of LA decomposed when furfural concentration was 0.3 mol/L at 200°C. Furthermore, sulfuric acid, as a hydrolysis catalyst, was found have a synergistic effect with furfural on LA decomposition, reaching a maximum promotion of 9.86% on LA decomposition compared with the effect acid or furfural alone. A kinetic model of LA decomposition considering the synergistic effect of furfural and acid concentration was established, and the activation energy of LA decomposition is 34.46 KJ/mol.

    更新日期:2020-01-17
  • Monoethanolamine Modified Attapulgite-based Amorphous Silica for the Selective Adsorption of CO2 from Simulated Biogas
    Energy Fuels (IF 3.021) Pub Date : 2020-01-17
    Qinglin Li; Hairong Zhang; Fen Peng; Can Wang; Hai-Long Li; Lian Xiong; Haijun Guo; Xin-De Chen

    Biogas upgrading technology is important for increasing the heating value of biogas through selective adsorption of CO2. In this work, a series of new monoethanolamine (MEA) modified attapulgite (ATP)-based amorphous silica (a-SiO2) sorbents with large surface area and oxygen vacancies were prepared by impregnation method for the selective adsorption of CO2 from simulated biogas. Fourier transform infrared spectroscopy (FTIR), Scanning electron microscope (SEM) and N2 adsorption/desorption results indicated that MEA with suitable loading was anchored onto the external surface of a-SiO2 which could improve the dispersion of rodlike fibers of ATP. MEA loading and reaction temperature optimization experiments showed that the 50MEA/a-SiO2 sorbent achieved the highest CO2 adsorption capacity of 2.14 mmol/g with amine efficiency of 5.22 mmol/g and 0.32 mol/mol at 60 °C. Furthermore, only a 6.3% and 4.7% reduction of CO2 adsorption capacity occurred after five adsorption-desorption cycles under simulated biogas at 30 °C and 60 °C adsorption, respectively, indicating the sorbent has good regenerability and thermal stability. The chemical adsorption was proved to be the CO2 adsorption mechanism of MEA modified ATP-based a-SiO2 sorbent by XRD and FTIR testing.

    更新日期:2020-01-17
  • Catalytic pyrolysis of centimeter-scale pine wood particles to produce hydrocarbon fuels: the effect of catalyst temperature and regeneration
    Energy Fuels (IF 3.021) Pub Date : 2020-01-17
    Yawei Chen; Kumar Aanjaneya; Arvind Atreya

    Pine wood particles were pyrolyzed in a vertical tube furnace at 500 °C followed by the upgradation of pyrolysis vapors using zeolite ZSM-5 at catalyst temperature from 400 °C to 600 °C. The catalyst was later regenerated to recover its acidity and activity. The bio-oil before catalysis was homogeneous and highly oxygenated and neither aromatic nor polycyclic aromatic hydrocarbons (PAH) were detected. The difference of water yield was very small for different catalytic pyrolysis cases and experimental results indicated that conversion of oxygen was mainly to CO and CO2 as the catalyst temperature increased. Chemical analysis of the bio-oil showed that aromatic hydrocarbons and PAH were formed in significant amounts upon catalytic treatment. Finally, the content of acids and ketones was reduced after catalysis, showing an improvement in the quality of bio-oil. The overall effect of the usage of regenerated catalyst on the pyrolysis products was not significant in the current study.

    更新日期:2020-01-17
  • NOx removal from flue gas using an ozone advanced oxidation process with injection of low concentration of ethanol: performance and mechanism
    Energy Fuels (IF 3.021) Pub Date : 2020-01-16
    Zhitao Han; Junming Wang; Tianyu Zou; Dongsheng Zhao; Cong Gao; Jingming Dong; Xin-Xiang Pan

    Effects of ethanol injection on NOx removal performance in an ozone advanced oxidation process were investigated based on a scale-up reaction system. Experimental results showed that the introduction of ethanol in simulated flue gas could enhance NOx removal performance greatly in O3-ethanol-NOx system. When initial NO concentration 400 ppm in flue gas at 150 ºC, the injection of 200 ppm O3 could oxidize approximately half of NO into NO2. When further introducing ~ 150 ppm ethanol vapor in flue gas, however, outlet NO concentration would drop sharply to ~ 68 ppm while outlet NO2 concentration drop down to ~ 165 ppm at the same time. This enhancement effect was ascribed to a synergistic reaction between O3, ethanol, and NOx in gas phase. The gas reaction products were analyzed by using GC-MS, and some kinds of nitro-compounds, such as nitroso methane, nitromethane, nitric acid methyl ester and nitric acid ethyl ester, had been found. It implied that some complex reactions might occur between ethanol and O3 at the presence of NOx, in which a large number of organic radicals and hydroxyl radicals had been produced. In addition, the effects of key operating parameters on NOx removal performance were investigated through comparing the changes in NOx concentration between O3-NOx and O3-ethanol-NOx systems, and the related reaction mechanism had also been discussed.

    更新日期:2020-01-17
  • Catalytic Pyrolysis of Poly(ethylene terephthalate) in the Presence of Metal Oxides for Aromatic Hydrocarbon Recovery Using Tandem μ-Reactor-GC/MS
    Energy Fuels (IF 3.021) Pub Date : 2020-01-15
    Shogo Kumagai; Ryota Yamasaki; Tomohito Kameda; Yuko Saito; Atsushi Watanabe; Chuichi Watanabe; Norio Teramae; Toshiaki Yoshioka
    更新日期:2020-01-16
  • Thermal Conductivity Enhancement and Shape Stabilization of Phase-Change Materials Using Three-Dimensional Graphene and Graphene Powder
    Energy Fuels (IF 3.021) Pub Date : 2020-01-15
    Wen Hao Li; S. Lai-Iskandar; Dunlin Tan; Luca Simonini; Jean-Paul Dudon; Fei Ni Leong; Roland Yingjie Tay; Siu Hon Tsang; Sunil C. Joshi; E. Hang Tong Teo

    The porous interconnected structure of three-dimensional graphene (3DC) combines the excellent thermal conductivity of graphene with an interconnected architecture, thereby creating a thermal network within composites infused with 3DC. In this study, improvements in thermal conductivity, latent heat of fusion (Hf), and shape stability of paraffin were compared between paraffin phase-change materials (PCMs) infused with 3DC and with discrete graphene flakes (GP) at the same filler loading to quantify the advantage of the interconnected structure. Paraffin infused with a 3DC of higher bulk density (3DCH) was also compared to identify the effects of increasing filler density. Thermal conductivity of the PCM composites was measured using the hot-disk method, and shape stabilization was compared through thermal cycling in an environment chamber. We found that the interconnected architecture of 3DC improved the properties of the paraffin matrix in multiple ways. 3DC improved the solidification process for paraffin with heterogeneous nucleation, helped retain the shape of the PCM composite over thermal cycling, reduced void formation within the PCM, and induced a large increase in thermal conductivity, which was 7.4 times and 5.2 times that of neat paraffin for composites infused with 3DCH and regular 3DC, respectively, with only a small trade-off in Hf.

    更新日期:2020-01-16
  • Influence of Cryogenic Liquid Nitrogen on Petro-Physical Characteristics of Mancos Shale: An Experimental Investigation
    Energy Fuels (IF 3.021) Pub Date : 2020-01-15
    Khalil Rehman Memon; Aftab Ahmed Mahesar; Muhammad Ali; Abdul Haque Tunio; Udit Surya Mohanty; Hamed Akhondzadeh; Faisal Ur Rahman Awan; Stefan Iglauer; Alireza Keshavarz

    The Mancos shale core sample investigated in the present research has been extracted from the late Cretaceous (upper cretaceous) geologic formation of USA. Shale gas is usually obtained by horizontal drilling which induces fractures to increase the flow ability of hydrocarbons. Therefore, it is important to understand the mechanical properties, heterogeneity, and their complexities associated with elastic properties of shale. An experimental study was conducted to examine the morphological characteristics of the Mancos shale core sample both pre- and post-treatment with cryogenic liquid nitrogen (LN2) for various immersion times, namely, 30, 60, and 90 min. The atomic force microscopy technique is used to understand the surface roughness, irregularities in core samples, and for more accuracy. Scanning electron microscopy (SEM) results were employed to visualize the formation of cracks caused by cryogenic liquid nitrogen. Results from SEM showed an increase in the fracture size from 2 to 25 μm with an increase in the aging time up to 90 min under the atmosphere of cryogenic LN2. Nano-indentation measurements revealed that the nano-indentation moduli of the Mancos samples subjected to applied forces of 50 and 200 mN underwent a decrease from 24.6 to 16.8 and 15.6 GPa, respectively, with an increase in cryogenic liquid nitrogen treatment time to 90 min. The permeability of the shale samples after LN2 treatment showed a significant increase, whereas increasing net confining stress from 1000 to 7000 psi for all untreated and treated rock samples exhibited a decrease in permeability, which is attributed to increased compaction between the pore spaces. Moreover, the porosity of the Mancos shale increased from 3.78 to 6.92% for pretreated and treated rock samples.

    更新日期:2020-01-16
  • Towards new descriptors of basic nitrogen compounds in middle distillates by 2D NMR
    Energy Fuels (IF 3.021) Pub Date : 2020-01-15
    David Proriol; Ludovic Chahen

    Basic nitrogen-compounds (N-compounds), present in middle distillates, can inhibit acidic catalysts used in hydrotreatment processes. A better knowledge of these compounds, especially the environment of the nitrogen atom, may be interesting to improve these processes. Herein, we propose a new promising methodology coupling the extraction of the basic N-compounds by flash chromatography with 2D NMR analysis. The NMR sequence Heteronuclear Single-Quantum Correlation (HSQC) allows to visualize specific C-H correlations and, with the help of the prediction software Advanced Chemistry Development/Laboratory (PS-ACDL), eleven areas of interest have been identified. The representativeness of these areas have been validated with data from literature and with a gas oil (GO) sample analysis. These areas are specific to C-H couples in pyridine, quinoline, isoquinoline and acridine derivatives and give a detailed fingerprint of basic N-compounds in the GO cut. Moreover, certain areas allow to describe the close environment of the nitrogen atom and allow, for example, to differentiate isoquinoline from quinoline derivatives.

    更新日期:2020-01-16
  • Time-resolved quantification of phenolic antioxidants and oxidation products in a model fuel by GC-EI-MS/MS
    Energy Fuels (IF 3.021) Pub Date : 2020-01-15
    Marcella Patricia Frauscher; Adam Agocs; Charlotte Besser; Alexandra Rögner; Günter Allmaier; Nicole Dörr

    Phenol-type components, amongst them butylated hydroxytoluene (BHT) are used as antioxidants (AO) to enhance thermo-oxidative stability in kerosene-type JET A-1 fuels. While the antioxidative effect of BHT is well known and often published, there is far less information regarding degradation products of BHT in fuel and their impact on the stability towards oxidation. In order to provide a time-resolved depletion of BHT in model kerosene, an artificial alteration method adapted for regular sampling was applied. Subsequently, the molecular structure of degradation products of BHT were identified by gas chromatography with electron impact ionisation mass spectrometry (GC-EI-MS). For the quantification of the residual BHT as well as two representatives of degradation products, namely 3,5-di-tert-butyl-4-hydroxybenzaldehyde (HBA) and 2,6-di-tert-butyl-p-benzoquinone (BQ) an analytical technique comprising a GC-EI triple quadrupole mass spectrometer run in the MS/MS mode was developed. BHT, BQ, and HBA were determined with a limit of detection and quantification (LOQ and LOD) below 1 ppb. The formation of BQ and HBA was observed shortly after the nascent degradation of BHT, while an increase of oxidation products deriving from the fuel ascended remarkably after full depletion of both, the initial AO BHT and the monitored oxidation products BQ and HBA. As the evolution of BQ and HBA followed a characteristic trend, the option is offered to use these compounds as markers to reliably predict the residual time until a total consumption or a predefined threshold of BHT is reached. This way, quality management of in-service or stored kerosene type fuels is enhanced.

    更新日期:2020-01-16
  • Properties and phase behavior of water-in-diesel microemulsion fuels stabilized by non-ionic surfactants in combination with aliphatic alcohol
    Energy Fuels (IF 3.021) Pub Date : 2020-01-15
    Alexander Ashikhmin; Maxim V. Piskunov; Vyacheslav A. Yanovsky; Wei-Mon Yan

    We investigate the properties and phase behavior of the water – diesel fuel – Neonol AF 9-6/2-ethylhexanol system, which is regarded as a promising microemulsion fuel. A pseudoternary diagram of the system has been obtained. In the diesel fuel/water (DF/W) ratio range from 98/2 to 50/50 and the emulsifier concentration 8-40 vol%, a region of microemulsions has been distinguished, generating particular interest as an alternative fuel. In the region under study, a reverse micellar phase L2 has existed predominantly. Fish-cut diagrams have been obtained for the DF/W ratios in the emulsifier concentration – temperature coordinates. An increase in the water fraction in microemulsions significantly has narrowed the range of their stability. The critical changes of microemulsion properties have been identified using the fish-cut diagrams. We have established the empirical relationship between the phase inversion temperature, the emulsifier concentration in the phase inversion point and the water fraction in microemulsions.

    更新日期:2020-01-16
  • Zeta Potential as a Measure of Asphalt Emulsion Stability
    Energy Fuels (IF 3.021) Pub Date : 2020-01-15
    Irvin Pinto; Ashley Buss

    Asphalt emulsions are oil-in-water emulsions widely used in pavement preservation treatments due to lower application temperatures and versatility for many pavement preservation applications. Asphalt emulsion stability is an important parameter to consider when choosing the type and formulation of an emulsion for a specific pavement preservation treatment. The stability of asphalt emulsions depend on the suspension of charged asphalt particles in an electrolyte solution. The particle size and the ionic stability play an important role and zeta potential provides a quantitative measure for tracking the stability of the emulsion. Zeta potential is the potential difference between the charged asphalt droplet surface in a dispersed phase and oppositely charged ions in a wateremulsifier solution which make up the continuous phase. A high positive or negative zeta potential indicates a stable emulsion, while zeta potential values approaching zero indicate flocculation. This study will consist of two phases. The first phase presents an experimental design to observe the effect of various formulation parameters on the zeta potential of quick-setting asphalt emulsions and create a statistical model of important effects. The second phase studies the influence aggregate fines of varying reactivity into the asphalt emulsion and determine the point of zero zeta potential for each formulation. This study aims to introduce the parameter of zeta potential into the design process of slurry-seal pavement preservation treatments and help improve the mixture design process and field performance of quick-setting asphalt emulsion mixtures.

    更新日期:2020-01-16
  • Effect of Using Rejuvenators on the Chemical, Thermal, and Rheological Properties of Asphalt Binders.
    Energy Fuels (IF 3.021) Pub Date : 2020-01-15
    Mohamed Elkashef; Michael D. Elwardany; Yanlong Liang; David Jones; John Harvey; Nicholas D. Bolton; Jean-Pascal Planche

    Rejuvenators are used to restore the properties of reclaimed asphalt pavement (RAP) binders through readjusting the balance between the asphaltenes and maltenes fractions. To properly understand the effect of rejuvenators, it is important to analyze the chemical changes in the rejuvenated binders and to relate these changes to the rheological properties of the binders. In this study, RAP binders were blended with a bio-based and an aromatic extract petroleum-based rejuvenator additive. Chemical and thermal techniques such as differential scanning calorimetry (DSC), attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy and saturates, aromatics, resins, and Asphaltene Determinator (SAR-ADTM) were used to analyze the control and rejuvenated RAP binders. Glass transition temperatures were obtained using DSC and correlated with rheological measurements using a dynamic shear rheometer (DSR) and a 4-mm plate geometry. From FTIR results, the evolution of the carbonyl and sulfoxide indices with aging were determined and correlated with the complex shear modulus DSR measurements at different aging stages. The SAR-AD analysis was used to determine the changes in the asphalt fractions with the addition of the rejuvenators. Temperature-frequency DSR sweeps and bending beam rheometer (BBR) testing were conducted, and master curves were constructed for the different binders. From these master curves, the effect of the different rejuvenators on the cross-over temperature, glass-transition temperature, and the intermediate region temperature range (TIR) was determined.

    更新日期:2020-01-16
  • Simultaneous Removal of CO2 and H2S from Biogas by Blends Amine Absorbents: A performance Comparison Study
    Energy Fuels (IF 3.021) Pub Date : 2020-01-15
    Woo Yun Lee; Sung Youl Park; Ki Bong Lee; Sungchan Nam

    ABSTRACT: Greenhouse gas treatment is urgently needed due to the impact of climate change caused by greenhouse gas emissions after global economic growth. In this study, post-combustion capture was carried out to screen absorbents for simultaneous absorption and regeneration of CO2 and H2S by-products of biogas, using MDEA (N-Methyldiethanolamine)-based additives. Twelve different absorbents were selected and compared according to the types of amine group and alcohol group. The mixture gas of 35 vol% CH4, 15 vol% CO2, and 50 ppm H2S balanced by N2 was used for absorption and regeneration. Absorption and regeneration were carried out at 35 °C and 80 °C, respectively. The absorbent concentration was fixed at 4.5 wt% for MDEA and 0.5 wt% for additives. In the continuous absorption and regeneration experiments, rich loading, lean loading, cyclic loading, absorption rate, and desorption rate were measured according to the loading values of CO2 and H2S using MDEA/additive mixed absorbent. CO2 rich loading was excellent in MDEA/DETA (diethylenetriamine) and CO2 cyclic capacity was excellent in MDEA/APA (bis(3-aminopropyl)amine). H2S rich loading was superior in MDEA/APA and H2S cyclic capacity was superior in MDEA/DETA. The CO2 absorption and regeneration rates were excellent in MDEA/PZ (piperazine), and the H2S absorption and regeneration rates were excellent in MDEA/AMP (2-amino-2-methyl-1-propanol). MDEA-based blending absorbent showed better absorption and regeneration performance than MDEA, and MDEA/PZ showed good performance for CO2 but very low performance for H2S. It was confirmed that MDEA/APA was superior for gas composition in the simultaneous absorption and regeneration of CO2 and H2S.

    更新日期:2020-01-15
  • DFT Study of Steam Effect on SeO2 Capture by CaO Adsorbents
    Energy Fuels (IF 3.021) Pub Date : 2020-01-15
    Yaming Fan; Yiran Fan; Yu Lou; Songtao Dong; Yuqun Zhuo; Shizhe Liu; Qiyu Weng; Pengbo Hu

    Emission of volatile and hazardous trace elements, including selenium emission from fossil fuel combustion, has become a major environmental concern. CaO adsorbent has proved highly effective in SeO2 capture. Steam is an important component in flue gas, which has been fully confirmed to be able to promote the adsorption of CO2 using CaO adsorbent. Due to the similar structure of SeO2 and CO2 molecule, the promotion effect provided by H2O for CO2 adsorption is expected to behave in a similar way to promote SeO2 adsorption by CaO. In this study, the promotion effect of steam on SeO2 adsorption was investigated and confirmed by density functional theory (DFT) calculation. The superficial OH formed during decomposition of H2O greatly promotes SeO2 adsorption.

    更新日期:2020-01-15
  • Modification of Microscopic Properties of Shale by Carbonic Acid Treatment: Implications for CO2-based Fracturing in Shale Formations
    Energy Fuels (IF 3.021) Pub Date : 2020-01-15
    Shouceng Tian; Panpan zhang; Mao Sheng; Tianyu Wang; Jizhou Tang; Lizhi Xiao

    Recent research has demonstrated that CO2, working as a fracturing fluid, possesses unique advantages during shale reservoirs development. Since water may exist in formations or be introduced into formations during drilling, carbonic acid would form after CO2’s dissolution into water. In this study, modification of microscopic surface properties of shale induced by carbonic acid treatment is comprehensively studied. Based on scanning electron microscope (SEM) imaging and energy dispersive spectrometer (EDS) mapping, the elemental evolution in the same position illustrates a certain correlation between the microstructure change and the dissolution of calcite and dolomite. Adhesion properties of the shale surface are revealed by atomic force microscopy (AFM). Adhesion force keeps relatively stable for the quartz regions and it shows an irregular increase in the non-quartz regions after carbonic acid treatment. Stereo images obtained by a confocal microscope show that the surface becomes smoother after carbonic acid treatment despite the formation of dissolution cavities. According to nanoindentation tests, Young's modulus and hardness are significantly reduced and the shale sample becomes more ductile after acid treatment. These findings provide a deep insight into the microscale alterations in shale surface induced by carbonic acid treatment, which contributes to the further assessment of CO2-based fracturing and CO2 sequestration.

    更新日期:2020-01-15
  • Re-recognition of MILD combustion regime by initial conditions of Tin and XO2 for methane in a non-adiabatic well-stirred reactor
    Energy Fuels (IF 3.021) Pub Date : 2020-01-15
    Congcong Luan; Shunta Xu; Bing Shi; Yaojie Tu; Hao Liu; Pengfei Li; Zhaohui Liu

    A more straightforward combustion map for identifying moderate or intense low-oxygen dilution (MILD) combustion regime in a well-stirred reactor (WSR) using initial inlet temperature (Tin) and oxygen mole fraction (XO2) has been proposed based on previous mathematical criteria provided by Cavaliere and Joannon 1. Furthermore, the detailed evolution of different combustion regimes under non-adiabatic condition has been comprehensively examined. Results show that there exists a critical XO2 (XO2*), below which MILD combustion can be established unconditionally as long as Tin exceeds the self-ignition point (Tsi), and beyond which Tin needs to be remarkably promoted to fulfill the mathematical criteria of MILD combustion. Thus, the two regions are termed unconditional MILD combustion (UMC) and conditional MILD combustion (CMC), respectively. For adiabatic condition XO2* is calculated to be 9.7%, indicating MILD combustion will be more easily achieved with oxygen-diluted oxidizer than oxygen-enriched counterpart. Interestingly, XO2* is found to climb as the heat loss ratio (HLR) increases, suggesting that enhancing the HLR of the WSR would help to expand the UMC region, namely more readily establishing of MILD combustion. In addition, high temperature combustion (HTC) can shift to CMC or even UMC by just enlarging HLR, providing a potential solution to realize MILD combustion in practical applications. However, the combustion regime would further shift to unsteady combustion (USC) or even no reaction (NR) regions once the heat is over-extracted. Hence, it would be a challenge for MILD combustion application in intense heat extraction scenarios, such as boilers. Interestingly, higher Tin and lower XO2 are found able to widen the UMC region under larger HLR conditions. Moreover, CO2 or H2O dilution would result in a wider UMC region compared to N2 dilution, while it is more pronounced for CO2 due to its highest XO2*. Besides, the shifting of combustion regime from HTC to MILD combustion by heat extraction would be more effective with CO2 dilution than either N2 or H2O dilution.

    更新日期:2020-01-15
  • HgCl2 Reduction under Low Temperature Selective Catalytic Reduction Atmosphere
    Energy Fuels (IF 3.021) Pub Date : 2020-01-15
    Shaojian Jiang; Liangfeng Cai; Jianping Yang; Haoyi Peng; Hui Liu; Hailong Li

    Mercury chloride (HgCl2) was considered as the dominant form of mercury in coal combustion flue gas. Abundant studies were conducted to investigate how to stimulate the oxidation of elemental mercury (Hg0) to form HgCl2 over selective catalytic reduction (SCR) catalysts, which could be easily removed in wet flue gas desulfurization system. However, as the reverse reaction of Hg0 oxidation, the reduction of HgCl2 was rarely studied. In this work, the entire mercury conversion process containing both Hg0 oxidation and HgCl2 reduction was investigated over a low temperature SCR catalyst. Nitric oxide (NO) alone did not inhibit Hg0 oxidation to HgCl2. However, NO with the assistance of ammonia (NH3) gas unexpectedly inhibited Hg0 conversion, even with the existence of hydrogen chloride (HCl) that was generally recognized to be able to greatly promote Hg0 oxidation. The co-existence of NO and NH3 induced a reduction of HgCl2, which partly counteracted the forward Hg0 oxidation reaction, thus led to a lower observed Hg0 oxidation efficiency. HgCl2 could not directly react with NO and NH3 to generate Hg0 at low temperature, while could react with reduced species such as hydroxy on the catalyst surface to produce Hg0. Such knowledge is of fundamental importance in accurate predicting Hg0 conversion efficiency over SCR catalysts and developing efficient Hg0 oxidation technologies.

    更新日期:2020-01-15
  • Sulfonated poly(ether ether ketone) hybrid membranes with amphoteric graphene oxide nanosheets as interfacial reinforcement for vanadium redox flow battery
    Energy Fuels (IF 3.021) Pub Date : 2020-01-14
    Bo Liu; Yunhu Jiang; Haixia Wang; Jing Ge; Haifeng Shi

    Sulfonated poly(ether ether ketone) (SPEEK) hybrid membranes are prepared by incorporating 2, 2'-benzidinedisulfonic acid-functionalized amphoteric graphene oxide (GO-BDSA) nanosheets. The optimized membrane permeability and ion selectivity greatly regulate the vanadium flow redox battery (VRFB) performance in terms of the formed interfacial action. At a 1wt% loading of GO-BDSA nanosheets, proton conductivity and ion selectivity of SPEEK/GO-BDSA-1 reach a maximum value such as 30.7 mS cm-1 and 43.3×103 S min cm-3, respectively. As compared with the self-discharge time of SPEEK (38 h) and Nafion 117 (33.5 h), SPEEK/GO-BDSA-1 hybrid membrane shows a longer one, 95.3 h. In the meantime, higher voltage efficiency (VE, 92 %) and energy efficiency (EE, 85 %) than SPEEK (VE, 87 % and EE, 82 %) and Nafion 117 (VE, 89 % and EE, 84 %) are confirmed at 50 mA·cm-2. The structure stability and durability of SPEEK/GO-BDSA-1 hybrid membrane is supposed after 250-time charge-discharge test., which is ascribed to the interaction from GO-BDSA nanosheets and SPEEK matrix. So, SPEEK/GO-BDSA hybrid membranes demonstrate a promising prospect for VRFB as the proton exchange membrane.

    更新日期:2020-01-15
  • Extending the Modified Regular Solution Model To Predict Component Partitioning to the Asphaltene-Rich Phase
    Energy Fuels (IF 3.021) Pub Date : 2020-01-14
    F. Ramos-Pallares; H. W. Yarranton

    The modified regular solution (MRS) model is an activity coefficient approach previously developed to predict the onset and amount of asphaltene precipitation from n-paraffin-diluted crude oils. The activity coefficients in this model are determined from an enthalpic contribution based on the regular solution theory and a Flory–Huggins (configurational) entropic contribution. The inputs are the molar volume and solubility parameter of the crude oil pseudo-components, which are defined on the basis of the saturate, aromatic, resin, and asphaltene (SARA) fractions; however, only asphaltenes and resins are free to partition between the two phases. Hence, the model cannot predict the amount and composition of the heavy asphaltene-rich phase. In this study, the MRS model was updated to account for the partitioning of all components based on phase equilibrium data from a Western Canada bitumen mixed with n-pentane and n-heptane at ambient conditions. To match the measured phase compositions, the entropic contribution in the solvent-rich phase was set to the Flory–Huggins term and the contribution from the asphaltene-rich phase was set to zero. An approach to predict the solubility parameters and density of the pseudo-components at other temperatures and pressures was also proposed. The model was tested on a data set containing phase mass and phase compositions of a Western Canada bitumen mixed with n-heptane, n-pentane, n-butane, and propane at temperatures from 20 to 250 °C and pressures up to 13 MPa. The average absolute deviations in the phase mass and compositions were 7 and 12 wt %, respectively. The maximum deviations were found for the asphaltene-rich phase compositions. The model was also tested on a data set of asphaltene yields from oils from different disparate geographical locations at temperatures from 0 to 50 °C at 0.1 MPa. The average absolute deviation was 1 wt %.

    更新日期:2020-01-15
  • Formation of Soluble Furanic and Carbocyclic Oxy-Organics during the Hydrothermal Carbonization of Glucose
    Energy Fuels (IF 3.021) Pub Date : 2020-01-14
    Ning Shi; Qiying Liu; Ying Liu; Lijun Chen; Ni Chen; Jiayu Peng; Longlong Ma
    更新日期:2020-01-15
  • 更新日期:2020-01-15
  • Solvent Synergists for Improved Kinetic Hydrate Inhibitor Performance of Poly(N-vinylcaprolactam)
    Energy Fuels (IF 3.021) Pub Date : 2020-01-14
    Malcolm A. Kelland; Erik G. Dirdal; Lilian H. S. Ree

    The synergetic effect of a range of different solvents on the kinetic hydrate inhibitor (KHI) performance of poly(N-vinylcaprolactam) (PVCap) has been investigated. The equipment used was a high-pressure (76 bar) rocking cell apparatus using slow constant cooling (approximately 1 °C/h from 20.5 °C) and a synthetic natural gas mixture forming structure II hydrate. The synergetic effect was investigated by adding 5000 ppm of a range of alcohols, glycol ethers, and ketones to a solution of 2500 ppm of PVCap (Mw = 10 000 g/mol). For many of the additives, the ranking of the synergetic effect can be explained with reference to the size, shape, and hydrophobicity of the main alkyl group (“tail”) in the molecule as well as the presence of a glycol ether group. Among all of the solvents investigated, the best synergetic effect was achieved by 4-methyl-1-pentanol. When 5000 ppm of 4-methyl-1-pentanol was added to 2500 ppm of PVCap, no hydrate formation occurred down to the minimum test temperature of 3 °C (subcooling at ca. 16.3 °C) in 15 parallel experiments compared to 10.4 °C for pure PVCap. Predictions for improved glycol ether synergists are given.

    更新日期:2020-01-15
  • Catalytic hydroconversion of a high-temperature coal tar over two attapulgite powder-supported nickel catalysts
    Energy Fuels (IF 3.021) Pub Date : 2020-01-14
    Yang-Yang Zhang; Xian-Yong Wei; Jing-Hui Lv; Zhi-Min Zong

    Abstract: Two attapulgite powder (AP)-supported nickel catalysts were prepared by thermally decomposing nickel tetracarbonyl onto AP in laboratory (L-Ni/AP) and factory (F-Ni/AP), respectively. The Ni nanoparticles are successfully dispersed on AP without evident agglomeration and mainly exist on the surface of AP in crystalline form with a small part entering into the mesopores. The soluble portion from non-catalytic hydroconversion (SPNCHC) and catalytic hydroconversion (SPCHC) of a high-temperature coal tar (HTCT) in cyclohexane over L-Ni/AP (SPCHC-L) and F-Ni/AP (SPCHC-F) were analyzed with a gas chromatograph/mass spectrometer and quadrupole exactive orbitrap mass spectrometer with APCI source operating in positive-ion model. The results show that the distribution of group components detected in SPNCHC are obviously different from that in either SPCHC-L or SPCHC-F. The relative content of non-substituted condensed arenes in SPCHC is ca. 75.0%, while the non-substituted polycyclanes and non-substituted hydroarenes are dominant in SPCHC-L and SPCHC-F. The relative abundances (RAs) of N3Ox (x =0-2) class species in SPNCHC are predominant in SPNCHC, while the RAs of hydrocarbons, N1Ox, and Ox (x =1,2) class species in SPCHC-L and SPCHC-F are the most abundant. Both catalysts are active for removing heteroatoms from the HTCT and hydrogenating aromatics in the HTCT, while L-Ni/AP is more effective for catalyzing the hydrogenation of the aromatics.

    更新日期:2020-01-15
  • Cleaning potential of selected coals in Shanxi Province, China. Part 1. Evaluation of geological factors affecting the cleaning potential
    Energy Fuels (IF 3.021) Pub Date : 2020-01-14
    Yuegang Tang; Xiaoshuai Wang; Harold H. Schobert; Cortland F. Eble; Chengwei Yang; Yufei Su; Kai Ye; Qingshun Cao; Guohua Liu

    The effects of geological factors on the cleaning potential of Chinese bituminous coals from Anping, Xizhuang, and Yitang exploration areas were studied. The cleaning potential was evaluated in terms of coal quality and cleanability. Distribution maps of resources with different cleaning potentials were prepared using mapping and geographical information software. To identify the geological factors responsible for the cleaning potentials of coal resources, the distribution of coal resources with different cleaning potentials were summarized with regard to the geological setting of the three exploration areas. The results are as follows. The depositional environment may have a large role in affecting the cleanabilities of coals, but it may not be the only factor. Coal which formed in an environment prone to producing pyrite can have a better cleanability than coal formed in a depositional environment that is more prone to producing organic sulfur. In contrast to the effects of depositional environment, the local structures (e.g., folds, faults, and collapse columns), where present, are generally considered to have little, if any, effect on the distribution of the coal with different cleaning potential characteristics.

    更新日期:2020-01-15
  • Experiments and Kinetic Modelling of Diffusion Flame Extinction of 2-Methylfuran, 2,5-Dimethylfuran and Binary Mixtures with Isooctane
    Energy Fuels (IF 3.021) Pub Date : 2020-01-14
    Amrit B Sahu; Saurabh Markendaya; Pabitra Badhuk; R.V. Ravikrishna

    This work presents an experimental and numerical study of extinction properties of 2,5-Dimethylfuran (DMF), 2-Methylfuran (MF) in counterflow diffusion flames at atmospheric pressure. The impact of addition of isooctane to the fuels is presented with two degrees of blends 25:75 and 50:50. The analysis was carried out for different levels of fuel loading ranging from 0.10 to 0.25 (volumetric) with the rest of the component being N2 as carrier gas. Extinction limits are observed to increase with increase in fuel loading and the resistance to extinction follows the order MF > Isooctane > DMF. Numerical predictions using the Tianjin mechanism are within 10% of the measurements for MF cases, while the Galway mechanism tends to underpredict at higher fuel loading conditions. For DMF flames, both the mechanisms perform relatively well at XF ≤ 0.14, however underpredict as the fuel loading is increased. Addition of isooctane to DMF led to an increase in the extinction limits at low fuel loading conditions but the impact of blending diminished at higher fuel loading conditions. On the other hand, addition of isooctane had minimum impact on MF flame’s extinction limit at low fuel loading conditions, while it led to a reduction in the resistance to extinction at higher fuel loadings. Numerical simulations by a mechanism proposed for isooctane-DMF-MF blend predict similar effects of blending, however, consistently tend to underpredict at higher fuel loading conditions. Quantitative reaction path diagrams show that the H-abstraction step is the dominant fuel consumption route for near-extinction MF and DMF flames. With increase in fuel loading, the role of C5H5 in the H-abstraction process increases in DMF/air flames. Reaction sensitivity analysis shows an increase in the importance of C5H5 kinetics in XF = 0.24 DMF flames as compared to XF = 0.14 along with the ring-opening step converting DMF to 3,4-hexadiene-2-one. In MF/air flames, the degree of change in sensitivities with fuel loading was found to be significantly low as compared to the DMF/air flames. Finally, reaction rate analysis was carried out to reveal that the slower consumption of MF causes the underprediction of the extinction strain rate by the Galway mechanism as compared to the Tianjin mechanism.

    更新日期:2020-01-15
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