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Table of Content
28 September 2021, Volume 37 Issue 9
    Machine learning of materials design and state prediction for lithium ion batteries
    Jiale Mao, Jiazhi Miao, Yingying Lu, Zheming Tong
    2021, 37(9):  1-11.  doi:10.1016/j.cjche.2021.04.009
    Abstract ( )   PDF (1626KB) ( )  
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    With the widespread use of lithium ion batteries in portable electronics and electric vehicles, further improvements in the performance of lithium ion battery materials and accurate prediction of battery state are of increasing interest to battery researchers. Machine learning, one of the core technologies of artificial intelligence, is rapidly changing many fields with its ability to learn from historical data and solve complex tasks, and it has emerged as a new technique for solving current research problems in the field of lithium ion batteries. This review begins with the introduction of the conceptual framework of machine learning and the general process of its application, then reviews some of the progress made by machine learning in both improving battery materials design and accurate prediction of battery state, and finally points out the current application problems of machine learning and future research directions. It is believed that the use of machine learning will further promote the large-scale application and improvement of lithium-ion batteries.
    Recent advances in cardiovascular stent for treatment of in-stent restenosis: Mechanisms and strategies
    Hang Yao, Yuwei He, Jinrong Ma, Lang Jiang, Jingan Li, Jin Wang, Nan Huang
    2021, 37(9):  12-29.  doi:10.1016/j.cjche.2020.11.025
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    Treatments of atherogenesis, one of the most common cardiovascular diseases (CVD), are continuously being made thanks to innovation and an increasingly in-depth knowledge of percutaneous transluminal coronary angioplasty (PTCA), the most revolutionary medical procedure used for vascular restoration. Combined with an expanding balloon, vascular stents used at stricture sites enable the long-time restoration of vascular permeability. However, complication after stenting, in-stent restenosis (ISR), hinders the advancement of vascular stents and are associated with high medical costs for patients for decades years. Thus, the development of a high biocompatibility stent with improved safety and efficiency is urgently needed. This review provides an overview of current advances and potential technologies for the modification of stents for better treatment and prevention of ISR. In particular, the mechanisms of in-stent restenosis are investigated and summarized with the aim to comprehensively understanding the pathogenesis of stent complications. Then, according to different therapeutic functions, the current stent modification strategies are reviewed, including polymeric drug eluting stents, biological friendly stents, prohealing stents, and gene stents. Finally, the review provides an outlook of the challenges in the design of stents with optimal properties. Therefore, this review is a valuable and practical guideline for the development of cardiovascular stents.
    Separation Science and Engineering
    NO removal performance of CO in carbonation stage of calcium looping for CO2 capture
    Wan Zhang, Yingjie Li, Yuqi Qian, Boyu Li, Jianli Zhao, Zeyan Wang
    2021, 37(9):  30-38.  doi:10.1016/j.cjche.2021.03.051
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    Calcium looping realizes CO2 capture via the cyclic calcination/carbonation of CaO. The combustion of fuel supplies energy for the calciner. It is unavoidable that some unburned char in the calciner flows into the carbonator, generating CO due to the hypoxic atmosphere in the carbonator. CO can reduce NO in the flue gases from coal-fired power plants. In this work, NO removal performance of CO in the carbonation stage of calcium looping for CO2 capture was investigated in a bubbling fluidized bed reactor. The effects of carbonation temperature, CO concentration, CO2 capture, type of CaO, number of CO2 capture cycles and presence of char on NO removal by CO in carbonation stage of calcium looping were discussed. CaO possesses an efficient catalytic effect on NO removal by CO. High temperature and high CO concentration lead to high NO removal efficiency of CO in the presence of CaO. Taking account of better NO removal and CO2 capture, the optimal carbonation temperature is 650℃. The carbonation of CaO reduces the catalytic activity of CaO for NO removal by CO due to the formation of CaCO3. Besides, the catalytic performance of CaO on NO removal by CO gradually decreases with the number of CO2 capture cycles. This is because the sintering of CaO leads to the fusion of CaO grains and blockage of pores in CaO, hindering the diffusion of NO and CO. The high CaO content and porous structure of calcium-based sorbents are beneficial for NO removal by CO. The presence of char promotes NO removal by CO in the carbonator. CO2/NO removal efficiencies can reach above 90%. The efficient simultaneous NO and CO2 removal by CO and CaO in the carbonation step of the calcium looping seems promising.
    Ethylene glycol purification by melt crystallization: Removal of 2-methoxyethanol impurity
    Tiefeng Wang, Jinxiang Dong
    2021, 37(9):  39-45.  doi:10.1016/j.cjche.2020.12.003
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    The coal (syngas)-to-ethylene glycol (CTEG), is contaminated with the naughty impurity 2-Methoxyethanol (ME) generated during the hydrogenation stage, which affect the quality of EG for fiber-grade polyester production. Distillation, is the employed separation process in industrial, which makes production complicated because of the heat sensitivity of the impurities system. Melt crystallization has been regarded as an effective technology to obtain high-purity organic compounds based on the melting points difference, which could avoid the problems by heating. In this work, we have explored the feasibility of the static melt crystallization on the separation of EG/ME in a jacketed crystallization tube. The experimental parameters were investigated, which covers crystallization and sweating stage in each step. The results showed that the purity of EG could reach ≥ 99.8% from the binary system studied via the quaternary separation process.
    Superior performance porous carbon nitride nanosheets for helium separation from natural gas: Insights from MD and DFT simulations
    Zilong Liu, Ge Zhao, Xiao Zhang, Lei Gao, Junqing Chen, Weichao Sun, Guanggang Zhou, Guiwu Lu
    2021, 37(9):  46-53.  doi:10.1016/j.cjche.2021.05.001
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    Increasing helium (He) demand in fundamental research, medical, and industrial processes necessitates efficient He purification from natural gas. However, most theoretically available membranes focus on the separation of two or three kinds of gas molecules with He and the underlying separation mechanism is not yet well understood. Using molecular dynamic (MD) and first-principle density function theory (DFT) simulations, we systematically demonstrated a novel porous carbon nitride membrane (g-C9N7) with superior performance for He separation from natural gas. The structure of g-C9N7 monolayer was optimized first, and the calculated cohesive energy confirmed its structural stability. Increasing temperature from 200 to 500 K, the g-C9N7 membrane revealed high He permeability, as high as 1.48×107 GPU (gas permeation unit, 1 GPU=3.35×10-10 mol·s-1·Pa-1·m-2) at 298 K, and also exhibited high selectivity for He over other gases (Ar, N2, CO2, CH4, and H2S). Then, the selectivity of He over Ne was found to decrease with increasing the total number of He and Ne molecules, and to increase with increasing He to Ne ratio. More interestingly, a tunable He separation performance can be achieved by introducing strain during membrane separation. Under the condition of 7.5% compressive strain, the g-C9N7 membrane reached the highest He over Ne selectivity of 9.41×102. It can be attributed to the low energy barrier for He, but increased energy barrier for other gases passing through the membrane, which was subject to a compressive strain. These results offer important insights into He purification using g-C9N7 membrane and opened a promising avenue for the screening of industrial grade gas separation with strain engineering.
    Catalysis, Kinetics and Reaction Engineering
    Reactivity study and kinetic evaluation of CuO-based oxygen carriers modified by three different ores in chemical looping with oxygen uncoupling (CLOU) process
    Cao Kuang, Shuzhong Wang, Ming Luo, Jun Zhao
    2021, 37(9):  54-63.  doi:10.1016/j.cjche.2020.12.027
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    In the chemical looping with oxygen uncoupling (CLOU) process, CuO is a promising material due to the high oxygen carrier capacity and exothermic reaction in fuel reactor but limited by the low melting point. The combustion rate of carbon is faster than the decoupling rate of oxygen carrier (OC). Hence, high temperature tolerance and rapid oxygen release rate of CuO modified by three different ores were investigated in this study. The kinetics analysis of oxygen decoupling with Cu-based oxygen carriers was also evaluated. Results showed that CuO modified by chrysolite had faster oxygen release rate than that of CuO. Limestone showed obvious positive effect on the oxidization process. The selected OCs could keep stable in at least 20 cycles, for about 1200 min. Shrinking core model (SCM) fitted well for the decoupling process in the temperature range of 1123-1223 K. Reduction rate kinetic information may aid in the development of chemical looping with oxygen uncoupling (CLOU) technologies during reactor design and process modeling. Ternary doped copper oxide with chrysolite and limestone could improve the reactivity of CuO in decoupling and coupling process and also improve the high temperature tolerance.
    Shape-selective alkylation of benzene with ethylene over a core-shell ZSM-5@MCM-41 composite material
    Zhenhao Shen, Chongwei Ma, Darui Wang, Junlin He, Hongmin Sun, Zhirong Zhu, Weimin Yang
    2021, 37(9):  64-71.  doi:10.1016/j.cjche.2021.05.030
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    A series of ZSM-5@MCM-41 core-shell composite materials prepared via a multi-cycle-sol-gel coating strategy is investigated as the catalyst for benzene alkylation with ethylene, in which both ethylbenzene and para-diethylbenzene (p-DEB) are aimed as the target products. With multi-cycle-sol-gel coating, the external acid sites on the samples are gradually passivated by the inert MCM-41 shell. As a result, the shape selectivity to p-DEB is greatly enhanced. Nevertheless, the coating of mesoporous MCM-41 shell on ZSM-5 accelerates deactivation of the catalyst only due to the dilution effect of ZSM-5 content in the catalyst at the same space velocity, which is a reason that core-shell ZSM-5@MCM-41 will potentially be a practical catalyst in shape selective alkylation of benzene. In order to enhance the yield of p-DEB on ZSM-5@MCM-41, the reaction conditions at the fixed bed reactor including temperature, the molar rate of benzene to ethylene and GHSV, are also optimized.
    Chemical Engineering Thermodynamics
    Theoretical insights on the hydration of quinones as catholytes in aqueous redox flow batteries
    Jipeng Li, Huan Xu, Jingqi Wang, Yujun Wang, Diannan Lu, Jichang Liu, Jianzhong Wu
    2021, 37(9):  72-78.  doi:10.1016/j.cjche.2021.06.016
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    Quinones have been widely studied as a potential catholyte in water-based redox flow batteries (RFBs) due to their ability to carry both electrons and protons in aqueous solutions. The wide variety of quinones and derivatives offers exciting opportunities to optimize the device performance while poses theoretical challenges to quantify their electrochemical behavior as required for molecular design. Computational screening of target quinones with high performance is far from satisfactory. While solvation of quinones affects their potential application in RFBs in terms of both electrochemical windows, stability, and charge transport, experimental data for the solvation structure and solvation free energies are rarely available if not incomplete. Besides, conventional thermodynamic models are mostly unreliable to estimate the properties of direct interest for electrochemical applications. Here, we analyze the hydration free energies of more than 1,400 quinones by combining the first-principles calculations and the classical density functional theory. In order to attain chemical insights and possible trends, special attention is placed on the effects of "backbones" and functional groups on the solvation behavior. The theoretical results provide a thermodynamic basis for the design, synthesis, and screening of high-performance catholytes for electrical energy storage.
    Liquid chemical looping gasification of biomass: Thermodynamic analysis on cellulose
    Wei Guo, Bo Zhang, Jie Zhang, Zhiqiang Wu, Yaowu Li, Bolun Yang
    2021, 37(9):  79-88.  doi:10.1016/j.cjche.2020.11.024
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    Liquid chemical looping technology is an innovation of chemical looping conversion technology. Using liquid metal oxide as the oxygen carrier during gasification process could prolong the service life of oxygen carrier and improve the process efficiency. In this paper, based on Gibbs minimum free energy method, the thermodynamic characteristics of biomass liquid chemical looping gasification were studied. Cellulose and lignin, the main components of biomass, were taken as the research objects. Bismuth oxide and antimony oxide were selected as liquid oxygen carriers. The results showed that when the temperature increased from 600℃ to 900℃, the output of H2 and CO in the products of cellulose gasification increased from 0.5 and 0.3 kmol to 1.3 and 2.6 kmol respectively. Different ratios of oxygen carriers to gasification raw materials had the best molar ratio. The addition of steam in the system was beneficial to the increase of H2 content and the increase of H2/CO molar ratio. Bi2O3 and Sb2O3 with different mass ratios were used as mixed oxygen carriers. The simulation results showed that the gasification temperature of biomass with different mixed oxygen carriers had the same equilibrium trend products. It could be seen from the results of product distribution that the influence of the mixing ratio of Bi2O3 and Sb2O3 on gas product distribution could be neglected. These results could provide simulation reference and data basis for subsequent research on liquid chemical looping gasification.
    Experimental and mechanistic study on chemical looping combustion of caking coal
    Xiuli Zhang, Zhengdong Gao, Yongzhuo Liu, Yuanhao Hou, Xiaoqing Sun, Qingjie Guo
    2021, 37(9):  89-96.  doi:10.1016/j.cjche.2021.01.013
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    Under high-temperature batch fluidized bed conditions and by employing Juye coal as the raw material, the present study determined the effects of the bed material, temperature, OC/C ratio, steam flow and oxygen carrier cycle on the chemical looping combustion of coal. In addition, the variations taking place in the surface functional groups of coal under different reaction times were investigated, and the variations achieved by the gas released under the pyrolysis and combustion of Juye coal were analyzed. As revealed from the results, the carbon conversion ratio and rate were elevated significantly, and the volume fraction of the outlet CO2 remained more than 92% under the oxygen carriers. The optimized reaction conditions to achieve the chemical looping combustion of Juye coal consisted of a temperature of 900℃, an OC/C ratio of 2, as well as a steam flow rate of 0.5 g·min-1. When the coal was undergoing the chemical looping combustion, volatiles primarily originated from the pyrolysis of aliphatic CH3 and CH2, and CO and H2 were largely generated from the gasification of aromatic carbon. In the CLC process, H2O and CO2 began to separate out at 270℃, CH4 and tar began to precipitate at 370℃, and the amount of CO2 was continuously elevated with the rise of the temperature.
    Biotechnology and Bioengineering
    Green synthesis of multifunctional carbon dots for anti-cancer and anti-fungal applications
    Shaojing Zhao, Li Huang, Yong Xie, Bin Wang, Feng Wang, Minhuan Lan
    2021, 37(9):  97-104.  doi:10.1016/j.cjche.2021.03.008
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    Carbon dots (CDs) have become popular nanomaterials in biomedical and agricultural fields. Herein we synthesized multifunctional CDs which showed anti-cancer and anti-fungal activities. The low cytotoxicity, stable fluorescence and high photothermal conversion efficiency enable the CDs with imaging-guided photothermal therapy. The CDs also exhibited intrinsic anti-fungal activity even at a low concentration, i.e., 40 mg·L-1 of CDs induced 20% mortality in cucumber downy mildew. Moreover, the large π-conjugated nanostructure and the richness of amino and hydroxyl groups make them a powerful delivery platform for flumorph (a fungicide) with a high loading efficiency of 47.18%. Meanwhile, the heat converted from the light can accelerate the release of flumorph from CDs, and thus efficiently kill fungus.
    3D Prussian blue/Pt decorated carbon nanofibers based screen-printed microchips for the ultrasensitive hydroquinone biosensing
    Tao Liu, Ying Xie, Lei Shi, Yu Liu, Zhenyu Chu, Wanqin Jin
    2021, 37(9):  105-113.  doi:10.1016/j.cjche.2021.02.017
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    Nowadays, water pollution has become more serious, greatly affecting human life and healthy. Electrochemical biosensor, a novel and rapid detection technique, plays an important role in the real-time and trace detection of water pollutants. However, the stability and sensitivity of electrochemical biosensors remain a great challenge for practical detections in real samples to the strong interferences derived from complex components and coagulation effects. In this work, we reported a novel three-dimensional architecture of Prussian blue nanoparticles (PBNPs)/Pt nanoparticles (PtNPs) composite film, using 3D interweaved carbon nanofibers as a supporting matrix, for the construction of screen-printed microchips-based biosensor. PtNPs with diameters of ~2.5 nm was highly dispersed on the carbon nanofibers (CNFs) to build a 3D skeleton nanostructure through a solvothermal reduction. Subsequently, uniform PBNPs were in-situ self-assembled on this skeleton to construct a 3D architecture of PB/Pt-CNF composite film. Due to the synergistic effects derived from this special feature, the as-prepared hydroquinone (HQ) biosensor chips can synchronously promote both surface area and conductivity to greatly enhance the electrocatalysis from enzymatic reaction. This biosensor has exhibited a high sensitivity of 220.28 μA·L·mmol-1·cm-2 with an ultrawide linear range from 2.5 μmol·L-1 to 1.45 mmol·L-1 at a low potential of 0.15 V, as well as the satisfactory reproducibility and usage stability. Besides, its accuracy was also verified in the assays of real water samples. It is highly expected that the 3D PB/Pt-CNF based screen-printed microchips will have wide applications in dynamic monitoring and early warning of analytes in the various practical fields.
    Characterization of wet microalgal cells pretreated with steam for lipid extraction
    Wenlu Song, Rui Huang, Hao Guo, Chunguang Yin, Chuanling Wang, Jun Cheng, Weijuan Yang
    2021, 37(9):  114-120.  doi:10.1016/j.cjche.2020.09.028
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    Steam pretreatment was employed to disrupt microalgal cells for lipids extraction. Effects of steam pretreatment on microstructure of microalgal cells were investigated through scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Effect of treatment on lipid extraction was also studied. Microalgal cell walls were distorted after steam pretreatment due to the hydrolysis of organic macromolecules contained in cell wall. Maximum curvature was increased from 1.88×10-6 m-1 to 1.43×10-7 m-1 after treatment with the steam at 130℃. The fractal dimension of microalgal cells increased from 1.25 to 1.30 after pretreatment for 15 min, and further increased to 1.47 when the pretreatment time was increased to 60 min. Increased steam pretreatment temperature and time enhanced the hydrolysis of organic macromolecules, and finally destroyed microalgal cell walls at pretreatment temperature of 130℃ and pretreatment time of 60 min. Lipid extracted from wet microalgal was significantly increased (2.1-fold) after pretreatment.
    A combo technology of autotrophic and heterotrophic denitrification processes for groundwater treatment
    Cemile Şeyma Arzum Yapıcı, Dilan Toprak, Müjgan Yıldız, Sinan Uyanık, Yakup Karaaslan, Deniz Uçar
    2021, 37(9):  121-127.  doi:10.1016/j.cjche.2020.10.015
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    In this study, a sequential process (heterotrophic up-flow column and completely mixed membrane bioreactors) was proposed combining advantages of the both processes. The system was operated for 249 days with simulated and real groundwater for nitrate removal at concentrations varying from 25 to 145 mg·L-1 NO3--N. The contribution of heterotrophic process to total nitrate removal in the system was controlled by dozing the ethanol considering the nitrate concentration. By this way, sulfur based autotrophic denitrification rate was decreased and the effluent sulfate concentrations were controlled. The alkalinity requirement in the autotrophic process was produced in the heterotrophic reactor, and the system was operated without alkalinity supplementation. Throughout the study, the chemical oxygen demand in the heterotrophic reactor effluent was (23.7±22) mg·L-1 and it was further decreased to (7.5±7.2) mg·L-1 in the system effluent, corresponding to a 70% reduction. In the last period of the study, the real groundwater containing 145 mg·L-1 NO3--N was completely removed. Membrane was operated without chemical washing in the first 114 days. Between days 115-249 weekly chemical washing was required.
    Covalent immobilization and characterization of Rhizopus oryzae lipase on core-shell cobalt ferrite nanoparticles for biodiesel production
    Saboura Ashkevarian, Jalil Badraghi, Fatemeh Mamashli, Behdad Delavari, Ali Akbar Saboury
    2021, 37(9):  128-136.  doi:10.1016/j.cjche.2020.11.003
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    Rhizopus oryzae lipase (ROL) was immobilized on the surface of silica coated amino modified CoFe2O4 nanoparticles and applied for biodiesel production. The results indicated more affinity of the ROL toward its substrate upon immobilization, as revealed by a lower Km value for the immobilized ROL compared to its free counterpart. Intrinsic fluorescence spectroscopy indicated a lower intensity for ROL immobilized on CoFe2O4 nanoparticles. Besides, immobilized ROL steady state anisotropy measurements presented lower values, which implied assembly of ROL molecules on magnetic nanoparticles upon immobilization as well as their restricted rotation upon covalent attachment. Thermal stability analysis revealed improved activity at higher temperatures for the immobilized enzyme compared to its free counterpart. Accordingly, Pace analysis to determine protein thermal stability revealed preservation of the protein conformation in the presence of increasing temperatures upon immobilization on nanoparticles. Finally, ROL immobilized on CoFe2O4 nanoparticles exhibited improved efficiency of biodiesel production in agreement with thermal activity profile. Therefore, the authors suggest application of the lipase molecules immobilized on CoFe2O4 nanoparticles for more efficient biodiesel production.
    The dynamic evolution of aggregated lithium dendrites in lithium metal batteries
    Xin Shen, Rui Zhang, Shuhao Wang, Xiang Chen, Chuan Zhao, Elena Kuzmina, Elena Karaseva, Vladimir Kolosnitsyn, Qiang Zhang
    2021, 37(9):  137-143.  doi:10.1016/j.cjche.2021.05.008
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    Lithium (Li) metal anodes promise an ultrahigh theoretical energy density and low redox potential, thus being the critical energy material for next-generation batteries. Unfortunately, the formation of Li dendrites in Li metal anodes remarkably hinders the practical applications of Li metal anodes. Herein, the dynamic evolution of discrete Li dendrites and aggregated Li dendrites with increasing current densities is visualized by in-situ optical microscopy in conjunction with ex-situ scanning electron microscopy. As revealed by the phase field simulations, the formation of aggregated Li dendrites under high current density is attributed to the locally concentrated electric field rather than the depletion of Li ions. More specifically, the locally concentrated electric field stems from the spatial inhomogeneity on the Li metal surface and will be further enhanced with increasing current densities. Adjusting the above two factors with the help of the constructed phase field model is able to regulate the electrodeposited morphology from aggregated Li dendrites to discrete Li dendrites, and ultimately columnar Li morphology. The methodology and mechanistic understanding established herein give a significant step toward the practical applications of Li metal anodes.
    Tungsten and phosphate polyanion co-doping of Ni-ultrahigh cathodes greatly enhancing crystal structure and interface stability
    Huawei Zhu, Haifeng Yu, Zhaofeng Yang, Hao Jiang, Chunzhong Li
    2021, 37(9):  144-151.  doi:10.1016/j.cjche.2021.04.001
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    The Ni-ultrahigh cathode material is one of the best choices for further increasing energy-density of lithium-ion batteries (LIBs), but they generally suffer from the poor structure stability and rapid capacity fade. Herein, the tungsten and phosphate polyanion co-doped LiNi0.9Co0.1O2 cathode materials are successfully fabricated in terms of Li(Ni0.9Co0.1)1-xWxO2-4y(PO4)y by the precursor modification and subsequent annealing. The higher bonding energy of W-O (672 kJ·mol-1) can extremely stabilize the lattice oxygen of Ni-rich oxides compared with Ni-O (391.6 kJ·mol-1) and Co-O (368 kJ·mol-1). Meanwhile, the stronger bonding of Ni-(PO43-) vs. Ni-O could fix Ni cations in the transition metal layer, and hence suppressing the Li/Ni disorder during the charge/discharge process. Therefore, the optimized Li(Ni0.9Co0.1)0.99W0.01O1.96(PO4)0.01 delivers a remarkably extended cycling life with 95.1% retention of its initial capacity of 207.4 mA·h·g-1 at 0.2 C after 200 cycles. Meantime, the heteroatoms doping does not sacrifice the specific capacity even at different rates.
    Stable interfaces constructed by concentrated ether electrolytes to render robust lithium metal batteries
    He Liu, Tao Li, Xiangqun Xu, Peng Shi, Xueqiang Zhang, Rui Xu, Xinbing Cheng, Jiaqi Huang
    2021, 37(9):  152-158.  doi:10.1016/j.cjche.2021.03.021
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    Lithium metal batteries (LMBs) are highly considered as promising candidates for next-generation energy storage systems. However, routine electrolytes cannot tolerate the high potential at cathodes and low potential at anodes simultaneously, leading to severe interfacial reactions. Herein, a highly concentrated electrolyte (HCE) region trapped in porous carbon coating layer is adopted to form a stable and highly conductive solid electrolyte interphase (SEI) on Li metal surface. The protected Li metal anode can potentially match the high-voltage cathode in ester electrolytes. Synergistically, this ingenious design promises high-voltage-resistant interfaces at cathodes and stable SEI with abundance of inorganic components at anodes simultaneously in high-voltage LMBs. The feasibility of this interface-regulation strategy is demonstrated in Li|LiFePO4 batteries, realizing a lifespan twice as long as the routine cells, with a huge capacity retention enhancement from 46.4% to 88.7% after 100 cycles. This contribution proof-of-concepts the emerging principles on the formation and regulation of stable electrode/electrolyte interfaces in the cathode and anode simultaneously towards the next-generation high-energy-density batteries.
    Glutamic acid-assisted hydrothermal recrystallization to configure bamboo-like carbon nanotubes for improved triiodide reduction
    Chun Yao, Jiangwei Chang, Yiwang Ding, Chang Yu, Jieshan Qiu
    2021, 37(9):  159-167.  doi:10.1016/j.cjche.2021.05.029
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    Carbon nanotubes (CNTs) have been far and wide employed as the counter electrodes (CEs) in dye-sensitized solar cells because of their individual physical and chemical properties. However, the techniques available now, such as chemical vapor deposition, arc discharge and laser ablation for synthesizing CNTs, commonly suffer from rigorous operations and complicated steps, which make the process difficult to be controlled. Herein, we present a simple and facile glutamic acid-assisted hydrothermal recrystallization strategy to construct bamboo-like CNTs (GHP-BC-x). Generally, the conventional organic dye 3,4,9,10-perylene tetracarboxylic dianhydride (PTCDA) is used as a precursor and glutamic acid efficiently promotes the recrystallization of the perylene cores' planar π-conjugated system in PTCDA under hydrothermal conditions and then self-assembles into one-dimensional nanorods with improved crystallization degree, finally resulting in the morphology of bamboo-like CNTs after carbonization. When applied as the counter electrodes, the GHP-BC-3 displays a remarkable power conversion efficiency of 8.25%, benefiting from the superb electrical conductivity and mass transfer dynamics, superior to that of Pt CE (7.62%).
    Effect of supports on the redox performance of pyrite cinder in chemical looping combustion
    Zhong Ma, Chuan Yuan, Shuai Zhang, Yonggang Lu, Junhui Xiong
    2021, 37(9):  168-174.  doi:10.1016/j.cjche.2020.11.034
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    Chemical looping combustion (CLC) is a clean and efficient flame-free combustion technology, which combust the fuels by lattice oxygen from a solid oxygen carrier with inherent CO2 capture. The development of oxygen carriers with low cost and high redox performance is crucial to the whole efficiency of CLC process. As the solid by-product from the sulfuric acid production, pyrite cinder presented excellent redox performance as an oxygen carrier in CLC process. The main components in pyrite cinder are Fe2O3, CaSO4, Al2O3 and SiO2 in which Fe2O3 is the active component to provide lattice oxygen. In order to systematic investigate the functions of supports (CaSO4, Al2O3 and SiO2) in pyrite cinder, three oxygen carriers (Fe2O3-CaSO4, Fe2O3-Al2O3 and Fe2O3-SiO2) were prepared and evaluated in this study. The results showed that Fe2O3-CaSO4 displayed high redox activity and cycling stability in the multiple redox cycles. However, both Fe2O3-Al2O3 and Fe2O3-SiO2 experienced serious deactivation during redox reactions. It indicated that the inert Fe-Si solid solution (Fe2SiO4) was formed in the spent Fe2O3-SiO2 sample, which decreased the oxygen carrying capacity of this sample. The XPS results showed that the oxygen species on the surface of Fe2O3-CaSO4 could be fully recovered after the 20 redox cycles. It can be concluded that CaSO4 is the key to the high redox activity and cycling stability of pyrite cinder.
    Theoretical study of reduction mechanism of Fe2O3 by H2 during chemical looping combustion
    Feng Liu, Jing Liu, Yu Li, Ruixue Fang
    2021, 37(9):  175-183.  doi:10.1016/j.cjche.2021.02.006
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    An atomic-level insight into the H2 adsorption and oxidation on the Fe2O3 surface during chemical-looping combustion was provided on the basis of density functional theory calculations in this study. The results indicated that H2 molecule most likely chemisorbs on the Fe2O3 surface in a dissociative mode. The decomposed H atoms then could adsorb on the Fe and O atoms or on the two neighboring O atoms of the surface. In particular, the H2 molecule adsorbed on an O top site could directly form H2O precursor on the O3-terminated surface. Further, the newly formed H-O bond was activated, and the H atom could migrate from one O site to another, consequently forming the H2O precursor. In the H2 oxidation process, the decomposition of H2 molecule was the rate-determining step for the O3-terminated surface with an activation energy of 1.53 eV. However, the formation of H2O was the rate-determining step for the Fe-terminated surface with an activation energy of 1.64 eV. The Fe-terminated surface is less energetically favorable for H2 oxidation than that the O3-terminated surface owing to the steric hindrance of Fe atom. These results provide a fundamental understanding about the reaction mechanism of Fe2O3 with H2, which is helpful for the rational design of Fe-based oxygen carrier and the usage of green energy resource such as H2.
    Mechanism analysis and simulation of methyl methacrylate production coupled chemical looping gasification system
    Wende Tian, Haoran Zhang, Zhe Cui, Xiude Hu
    2021, 37(9):  184-196.  doi:10.1016/j.cjche.2021.02.024
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    Nowadays, the efficient and cleaner utilization of coal have attracted wide attention due to the rich coal and rare oil/gas resources structure in China. Coal chemical looping gasification (CCLG) is a promising coal utilization technology to achieve energy conservation and emission reduction targets for highly pure synthesis gas. As a downstream product of synthesis gas, methyl methacrylate (MMA), is widely used as raw material for synthesizing polymethyl methacrylate and resin products with excellent properties. So this paper proposes a novel system integrating MMA production and CCLG (CCLG-MMA) processes aiming at "energy saving and low emission", in which the synthesis gas produced by CCLG and purified by dry methane reforming (DMR) reaction and Rectisol process reacts with ethylene for synthesizing MMA. Firstly, the reaction mechanism of CCLG is investigated by using Reactive force field (ReaxFF) MD simulation based on atomic models of char and oxygen carrier (Fe2O3) for obtaining optimum reaction temperature of fuel reactor (FR). Secondly, the steady-state simulation of CCLG-MMA system is carried out to verify the feasibility of MMA production. The amount of CO2 emitted by CCLG process and DMR reaction is 0.0028 (kg CO2)-1·(kg MMA)-1. The total energy consumption of the CCLG-MMA system is 45521 kJ·(kg MMA)-1, among which the consumption of MMA production part is 25293 kJ·(kg MMA)-1. The results show that the CCLG-MMA system meets CO2 emission standard and has lower energy consumption compared to conventional MMA production process. Finally, one control scheme is designed to verify the stability of CCLG-MMA system. The CCLG-MMA integration strategy aims to obtain highly pure MMA from multi-scale simulation perspectives, so this is an optimal design regarding all factors influencing cleaner MMA production.
    Experimental and numerical simulation of lignite chemical looping gasification with phosphogypsum as oxygen carrier in a fluidized bed
    Wang Du, Liping Ma, Jing Yang, Wei Zhang, Ran Ao
    2021, 37(9):  197-207.  doi:10.1016/j.cjche.2021.01.006
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    Phosphogypsum (PG) is a solid waste produced in the wet process of producing phosphoric acid. Lignite is a kind of promising chemical raw material. However, the high sulfur of lignite limits the utilization of lignite as a resource. Based on fluidized bed experiments, the optimal reaction conditions for the production syngas by lignite chemical looping gasification (CLG) with PG as oxygen carrier were studied. The study found that the optimal reaction temperature should not exceed 1123 K; the mole ratio of water vapor to lignite should be about 0.2; the mole ratio of PG oxygen carrier to lignite should be about 0.6. Meanwhile, commercial software Comsol was used to establish a fuel reaction kinetics model. Through computational fluid dynamics (CFD) numerical simulation, the process of reaction in fluidized bed were well captured. The model was based on a two-fluid model and coupled mass transfer, heat transfer and chemical reactions. This study showed that the fluidized bed presents a flow structure in which gas and solid coexist. There was a high temperature zone in the middle and lower parts of the fluidized bed. It could be seen from the results of the flow field simulated that the fluidized bed was beneficial to the progress of the gasification reaction.
    Design of core-shell nickel oxide/silicon carbide whiskers towards excellent microwave absorption property
    Jingpeng Chen, Ge Song, Zhuo Liu, Lijing Xie, Shoushun Zhang, Chengmeng Chen
    2021, 37(9):  208-216.  doi:10.1016/j.cjche.2021.03.047
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    Toward the increasingly serious problem of electromagnetic wave pollution, the development of absorbing material with the properties of the light, thin, wide, strong, and multiple applications scenarios is still a huge challenge. Herein, the core-shell nickel oxide/silicon carbide whiskers (NiO/SiCw) with variational NiO morphologies (tulle-, flower, and rod-like) were designed and fabricated via a facile pre-hydrothermal method and post-annealing process. For the NiO shell morphology, it can effectively be controlled by the proportion of Ni(NO3)2·6H2O, NH4Cl, and CO(NH2)2. The structure of NiO/SiCw samples was investigated by XRD, SEM, XPS, TEM, and N2 absorption-desorption. Compared to other morphologies of NiO, the flower-like NiO/SiCw possess a porous structure and large surface area that can benefit from the multiple reflections and attenuation of the microwave. As an absorber, the composite with the flower-like NiO/SiCw filler loading of 50% manifests a superior microwave attenuation capability due to its special porous structure, good impedance matching, and large dielectric loss induced from heterojunction interfacial polarization. The minimum reflection loss of flower-like NiO/SiCw is up to -56.8 dB with a thickness of 1.9 mm, and the maximum effective absorption bandwidth (EAB) reaches 5.17 GHz. The as-prepared flower-like NiO/SiCw with strong absorption, thin thickness, and width EAB can meet the potential requirements for microwave absorption materials under oxidation environments.
    Ultrafine tuning of the pore size in zeolite A for efficient propyne removal from propylene
    Chaohui He, Rajamani Krishna, Yang Chen, Jiangfeng Yang, Jinping Li, Libo Li
    2021, 37(9):  217-221.  doi:10.1016/j.cjche.2020.11.037
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    The removal of trace propyne (C3H4) from propyne/propylene (C3H4/C3H6) mixtures is a technical and challenging task during the production of polymer-grade propylene in view of their very similar size and physical properties. While some progress has been made, it is still very challenging to use some highly stable and commercially available porous materials via an energy-efficient adsorptive separation process. Herein, we report the ultrafine tuning of the pore apertures in type-A zeolites for the highly efficient removal of trace amounts of C3H4 from C3H4/C3H6 mixtures. The resulting ion-exchanged zeolite 5A exhibits a large C3H4 adsorption capacity (2.3 mmol g-1 under 10-4 MPa) and high C3H4/C3H6 selectivity at room temperature, which were mainly attributed to the ultrafine-tuned pore size that selectively blocks C3H6 molecules, while maintaining the strong adsorption of C3H4 at low pressure region. High purity of C3H6 (>99.9999%) can be directly obtained on this material under ambient conditions, as demonstrated by the experimental breakthrough curves obtained for both 1/99 and 0.1/99.9 (V/V) C3H4/C3H6 mixtures.
    An efficient corrosion inhibitor of cassava starch graft copolymer for aluminum in phosphoric acid
    Shuduan Deng, Xianghong Li, Guanben Du
    2021, 37(9):  222-231.  doi:10.1016/j.cjche.2020.08.013
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    Starch is one of the richest natural polymers with low-cost, non-toxic and biodegradable, but is seldom directly used as corrosion inhibitor due to its poor inhibitive ability and low water solubility. To solve this problem, cassava starch-acryl amide graft copolymer (CS-AAGC) was prepared through grafting acryl amide (AA) with cassava starch (CS), and it was firstly examined as an efficient inhibitor for 1060 aluminum in 1.0 mol·L-1 H3PO4 media. The adsorption behavior of CS-AAGC and its electrochemical mechanism were investigated by weight loss and electrochemical methods. Additionally, the inhibited aluminum surface was fully characterized by a series of SEM, AFM, contact angle measurements and XPS. Results confirm that CS-AAGC performs better inhibitive ability than CS, AA or CS/AA mixture, and the maximum inhibition efficiency of 1.0 g·L-1 CS-AAGC is 90.6% at 20℃. CS-AAGC acts as a mixed-type inhibitor while mainly retards the anodic reaction. EIS has three time constants, and the polarization resistance is significantly increased in the presence of CS-AAGC. The micrograph of inhibited aluminum surface is of hydrophobic nature with low surface roughness and little corrosion degree.