2018 Vol. 3, No. 3

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Short Review
Ionic liquids: Functionalization and absorption of SO2
Shuhang Ren, Yucui Hou, Kai Zhang, Weize Wu
2018, 3(3): 179-190. doi: 10.1016/j.gee.2017.11.003
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Room-temperature ionic liquids (ILs), which have excellent properties, such as high gas absorption abilities, extremely low volatility and tunable structures, are regarded as environmentally-friendly absorbents and widely used in SO2 absorption and separation. As a result, a large number of ILs have been synthesized to capture SO2 from flue gas or simulated gas, but a part of them just have physical interaction with SO2 and can hardly absorb SO2 when the content of SO2 is very low. Hence, functional ILs, which can chemically absorb a large amount of SO2 with low contents, have been designed and synthesized for SO2 capture. Up to now, many kinds of functional ILs were investigated for SO2 absorption from flue gas. In this review, the functional ILs are classified into guanidinium based ILs, hydroxyl ammonium based ILs, imidazolium/pyridinium based ILs, quaternary ammonium based ILs, phosphonium based ILs, and other kinds of ILs according to their cations. The capacities of SO2 absorption in these ILs, the mechanism of the absorption, and the ways to enhance the absorption are briefly introduced. The prospect of functional ILs for their application in SO2 removal is presented. The present problems and the further studies are also discussed.
Review article
Applications of metal–organic frameworks for green energy and environment: New advances in adsorptive gas separation, storage and removal
Bin Wang, Lin-Hua Xie, Xiaoqing Wang, Xiao-Min Liu, Jinping Li, Jian-Rong Li
2018, 3(3): 191-228. doi: 10.1016/j.gee.2018.03.001
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The separation of gas molecules with similar physicochemical properties is of high importance but practically entails a substantial energy penalty in chemical industry. Meanwhile, clean energy gases such as H2 and CH4 are considered as promising candidates for the replacement of traditional fossil fuels. However, the technologies for the storage of these gases are still immature. In addition, the release of anthropogenic toxic gases into the atmosphere is a worldwide threat of growing concern. Both in academia and industry, considerable research efforts have been devoted to developing advanced porous materials for the effective and energy-efficient separation, storage, or capture of the related gases. In contrast to conventional inorganic porous materials such as zeolites and activated carbons, metal–organic frameworks (MOFs) are considered as a type of promising materials for gas separation and storage. In this contribution, we review the recent research advance of MOFs in some relevant applications, including CO2 capture, O2 purification, separation of light hydrocarbons, separation of noble gases, storage of gases (CH4, H2, and C2H2) for energy, and removal of some gaseous air pollutants (NH3, NO2, and SO2). Finally, an outlook regarding the challenges of the future research of MOFs in these directions is given.
Research paper
Designing all-solid-state Z-Scheme 2D g-C3N4/Bi2WO6 for improved photocatalysis and photocatalytic mechanism insight
Mao Mao, Shuowei Zhao, Zhigang Chen, Xiaojie She, Jianjian Yi, Kaixiang Xia, Hui Xu, Minqiang He, Huaming Li
2018, 3(3): 229-238. doi: 10.1016/j.gee.2017.11.001
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Bi2WO6 was modified by two-dimensional g-C3N4 (2D g-C3N4) via a hydrothermal method. The structure, morphology, optical and electronic properties were investigated by multiple techniques, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy spectra (XPS), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Ultraviolet-visible diffuse reflection spectroscopy (DRS), photocurrent and electrochemical impedance spectroscopy (EIS), electron spin resonance (ESR), respectively. Rhodamine B (RhB) was used as the target organic pollutant to research the photocatalytic performance of as-prepared composites. The Bi2WO6/2D g-C3N4 exhibited a remarkable improvement compared with the pure Bi2WO6. The enhanced photocatalytic activity was because the photogenerated electrons and holes can quickly separate by Z-Scheme passageway in composites. The photocatalytic mechanism was also researched in detail through ESR analysis.
Fabrication of CuOx thin-film photocathodes by magnetron reactive sputtering for photoelectrochemical water reduction
Tian Xie, Tao Zheng, Ruiling Wang, Yuyu Bu, Jin-Ping Ao
2018, 3(3): 239-246. doi: 10.1016/j.gee.2018.01.003
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The CuOx thin film photocathodes were deposited on F-doped SnO2 (FTO) transparent conducting glasses by alternating current (AC) magnetron reactive sputtering under different Ar:O2 ratios. The advantage of this deposited method is that it can deposit a CuOx thin film uniformly and rapidly with large scale. From the photoelectrochemical (PEC) properties of these CuOx photocathodes, it can be found that the CuOx photocathode with Ar/O2 30:7 provide a photocurrent density of −3.2 mA cm−2 under a bias potential −0.5 V (vs. Ag/AgCl), which was found to be twice higher than that of Ar/O2 with 30:5. A detailed characterization on the structure, morphology and electrochemical properties of these CuOx thin film photocathodes was carried out, and it is found that the improved PEC performance of CuOx semiconductor photocathode with Ar/O2 30:7 attributed to the less defects in it, indicating that this Ar/O2 30:7 is an optimized condition for excellent CuOx semiconductor photocathode fabrication.
Parameterization of COSMO-RS model for ionic liquids
Jingli Han, Chengna Dai, Gangqiang Yu, Zhigang Lei
2018, 3(3): 247-265. doi: 10.1016/j.gee.2018.01.001
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The adjustable parameters in the popular conductor-like screening model for real solvents (COSMO-RS) within the Amsterdam density functional (ADF) framework have been re-optimized to fit for the systems containing ionic liquids (ILs). To get the optimal values of misfit energy constant a′, hydrogen bond coefficient chb and effective contact surface area of a segment aeff, 2283 activity coefficient data points at infinite dilution and 1433 CO2 solubility data points exhaustively collected from references were used as training set. The average relative deviations (ARDs) of activity coefficients at infinite dilution and CO2 solubility between experimental data and predicted values are 32.22% and 17.61%, respectively, both of which are significantly lower than the original COSMO-RS versions. Predictions for other activity coefficients of solutes in ILs, solubility data of CO2 in pure ILs and the binary mixtures of ILs at either high or low temperatures, and vapor–liquid equilibrium (VLE) for binary systems involving ILs have also been performed to demonstrate the validity of the parameterization of COSMO-RS model for ILs. The results showed that the predicted results by COSMO-RS model with the new optimized parameters are in much better agreement with experimental data than those by the original versions over a wide temperature and pressure range. The COSMO-RS model for ILs presented in this work improves the prediction accuracy of thermodynamic properties for the systems containing ILs, which is always highly desirable for general chemical engineers.
Vehicle fuel from biogas with carbon membranes; a comparison between simulation predictions and actual field demonstration
Shamim Haider, Arne Lindbråthen, Jon Arvid Lie, Petter Vattekar Carstensen, Thorbjørn Johannessen, May-Britt Hägg
2018, 3(3): 266-276. doi: 10.1016/j.gee.2018.03.003
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The energy contents of biogas could be significantly enhanced by upgrading it to vehicle fuel quality. A pilot-scale separation plant based on carbon hollow fiber membranes for upgrading biogas to vehicle fuel quality was constructed and operated at the biogas plant, Glør IKS, Lillehammer Norway. Vehicle fuel quality according to Swedish legislation was successfully achieved in a single stage separation process. The raw biogas from anaerobic digestion of food waste contained 64 ± 3 mol% CH4, 30–35 mol% CO2 and less than one percent of N2 and a minor amount of other impurities. The raw biogas was available at 1.03 bar with a maximum flow rate of 60 Nm3 h−1. Pre-treatment of biogas was performed to remove bulk H2O and H2S contents up to the required limits in the vehicle fuel before entering to membrane system. The membrane separation plant was designed to process 60 Nm3 h−1 of raw biogas at pressure up to 21 bar. The initial tests were, however, performed for the feed flow rate of 10 Nm3 h−1 at 21 bar. The successful operation of the pilot plant separation was continuously run for 192 h (8 days). The CH4 purity of 96% and maximum CH4 recovery of 98% was reached in a short-term test of 5 h. The permeate stream contained over 20 mol% CH4 which could be used for the heating application. Aspen Hysys® was integrated with ChemBrane (in-house developed membrane model) to run the simulations for estimation of membrane area and energy requirement of the pilot plant. Cost estimation was performed based on simulation data and later compared with actual field results.
Carbon coated ultrasmall anatase TiO2 nanocrystal anchored on N,S-RGO as high-performance anode for sodium ion batteries
Lingfei Zhao, Tong Tang, Weihua Chen, Xiangming Feng, Liwei Mi
2018, 3(3): 277-285. doi: 10.1016/j.gee.2018.01.004
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Anatase TiO2 has been investigated as one of the most promising anode materials for sodium ion batteries (SIBs) with low cost and high theoretical capacity. Herein, a composite material of TiO2/N,S-RGO@C with carbon coated ultrasmall anatase TiO2 anchored on nitrogen and sulfur co-doped RGO matrix was successfully prepared by a rational designed process. The composite structure exhibited ultrasmall crystal size, rich porous structure, homogeneous heteroatoms doping and thin carbon coating, which synergistically resulted in elevated electron and ion transfer. The anode exhibited high rate capacities with good reversibility under high rate cycling. The carbon coating was investigated to be effective to prevent active material falling and lead to long term cycling performance with a high capacity retention of 181 mAh g−1 after 2000 cycles at 2 C. Kinetic studies were carried out and the results revealed that the superior performance of the composite material were derived from the decreased charge transfer resistance and elevated ion diffusion. Results suggested that the TiO2/N,S-RGO@C composite is a promising anode material for sodium ion batteries.
FCC coprocessing oil sands heavy gas oil and canola oil. 2. Gasoline hydrocarbon type analysis
Siauw H. Ng, Nicole E. Heshka, Cecile Lay, Edward Little, Ying Zheng, Qiang Wei, Fuchen Ding
2018, 3(3): 286-301. doi: 10.1016/j.gee.2018.03.002
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This study set out to gain a deeper understanding of a fluid catalytic cracking (FCC) coprocessing approach using canola oil mixed with bitumen-derived heavy gas oil (HGO), for the production of partially-renewable gasoline, with respect to its composition and quality. The FCC coprocessing approach may provide an alternative solution to reducing the carbon footprint and to meet government regulatory demands for renewable transportation fuels. In this study, a mixture of 15 v% canola oil in HGO was catalytically cracked with a commercial equilibrium catalyst under typical FCC conditions. Cracking experiments were performed using a bench-scale Advanced Cracking Evaluation (ACE) unit at a fixed weight hourly space velocity of 8 h−1, 490–530 °C, and catalyst/oil ratios of 4–12 g/g. The total liquid product samples were injected via an automatic sampler and a prefractionator (to remove +254 °C) into a gas chromatographic system containing a series of columns, traps, and valves designed to separate each of the hydrocarbon types. The analyzer gives detailed hydrocarbon types of −200 °C gasoline, classified into paraffins, iso-paraffins, olefins, naphthenes, and aromatics by carbon number up to C11 (C10 for aromatics). For a feed cracked at a given temperature, the gasoline aromatics show the highest selectivity in terms of weight percent conversion, followed by saturated iso-paraffins, saturated naphthenes, unsaturated iso-paraffins, unsaturated naphthenes, unsaturated normal paraffins, and saturated normal paraffins. As conversion increases, both aromatics and saturated iso-paraffins increase monotonically at the expense of other components. Hydrocarbon type analysis and octane numbers with variation in feed type, process severity (temperature and catalyst/oil ratio), and conversion are also presented and discussed.
Evaluating the effectiveness of using ClO2 bleaching as substitution of traditional Cl2 on PCDD/F reduction in a non-wood pulp and paper mill using reeds as raw materials
Lili Yang, Liping Fang, Linyan Huang, Yuyang Zhao, Guorui Liu
2018, 3(3): 302-308. doi: 10.1016/j.gee.2017.07.002
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The effectiveness of ClO2 bleaching as a replacement for conventional Cl2 bleaching, which is intensively practiced in developing countries, to reduce polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in non-wood pulp and paper mills has not been field tested. The first field study was performed to investigate PCDD/F variations when ClO2 bleaching was used as a substitute for conventional Cl2 bleaching in a non-wood pulp and paper mill. It was found that the PCDD/F toxic equivalents (TEQs) in solid and effluent samples were approximately 1.3–14.9 times lower when ClO2 bleaching was used instead of the conventional Cl2 bleaching. 2,3,7,8-Substituted tetrachlorinated dibenzofurans (2,3,7,8-TCDF) were the dominant contributors to total PCDD/F TEQs in samples from the investigated mill when using conventional Cl2 bleaching. The formation amounts of 2,3,7,8-TCDF were reduced from 1.56–2.76 pg TEQ/g to 0.02–0.32 pg TEQ/g in solid samples when ClO2 bleaching was used instead of the conventional Cl2 bleaching. The replacement of Cl2 with ClO2 might decrease the chlorination reactions of dibenzofuran as potential precursors, and thus reduce the formation amounts of 2,3,7,8-TCDF. The results could provide important knowledge for suggesting the best available technique for PCDD/F reduction for non-wood pulp and paper mills in developing countries.

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