Table of Content

    30 December 2021, Volume 23 Issue 4
    Scientific Research
    Carbon Encapsulated Nickel Nanocomposites for the Cathode in Advanced Lithium Sulfur Batteries
    Yang Yuxiang, Xie Jingxin, Wu Genghuang, Zhu Na, Li Huan, Rong Junfeng
    2021, 23(4):  1-6. 
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    Lithium sulfur (Li-S) batteries are poised to be the next generation of high-density energy storage devices. In recent years, the concept of “electrocatalysis” has been introduced into the field of Li-S batteries, and some transition metals have been proved to catalyze the electrochemical conversion reaction of sulfur species. In this study, carbon encapsulated nickel nanoparticles (Ni@C) with a specific surface area of 146 m2/g are shown to play a definitive electrocatalytic role for the sulfur cathode. With Ni@C incorporated, the Ni@C/G-S electrode achieved a better electrochemical performance than the G-S electrode. Moreover, the reversible capacity and cycle stability were further improved through chemical modifications of the carbon shell. The influence of doping with different elements on the Li-S battery performance was also investigated in detail. Higher specific capacities of 1229 mAh/g, 927 mAh/g, and 830 mAh/g were achieved at 0.2 C, 0.5 C, and 1.0 C for the N-Ni@C-G/S electrode. Besides, the B-Ni@C-G/S electrode possessed a best cycle stability.
    MnxCo3-xO4 microtubules with enhanced catalytic activity towards toluene combustion:effects of redox property and oxygen species
    Zhang Hanyu Hu yue Zhang Xiaohan Sun Mengyao Liu Rui Jin Quan Qi Jian
    2021, 23(4):  7-17. 
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    Redox property and oxygen species play important role in the catalytic oxidation of volatile organic compounds (VOCs). In this paper, a series of MnxCo3-xO4 catalysts with tubular structure were synthesized and applied for the catalytic combustion of toluene. Various characterization technologies were employed to reveal the relationship between the catalytic performance of the MnxCo3-xO4 catalysts and Mn doping. The results of XRD, SEM and N2 adsorption-desorption showed that the Mn doping had significant effects on the structure and morphology of the MnxCo3-xO4 catalysts. The H2-TPR, O2-TPD and XPS results proved that the strong interaction between Co and Mn resulted in the enhanced Olatt mobility, richer active oxygen species, and enhanced redox property in comparison with the pure Co3O4 sample, which were crucial to the improvement of the catalytic activity of Co-Mn catalysts. The best catalyst, Co5-Mn5 sample, exhibited a good and stable activity to catalytically oxidize toluene at low temperatures even in the presence of water vapor, indicating that it is a potential material for the practically catalytic industrialization for the abatement of toluene.
    Dechlorination of Crude Oil by Phase Transfer Catalyst in Nucleophilic Substitution Reaction
    Gu Jin, Han Xin†, Liu Jichang, Huang Zihao, Xing Biao
    2021, 23(4):  18-28. 
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    Dechlorination of crude oil is an effective way to alleviate corrosion in refinery units, and the critical process is the removal of organochlorine which can be efficiently removed through nucleophilic substitution reaction catalyzed by phase transfer. Herein, seven typical chlorinated alkanes were selected as model compounds to study the mechanism of dechlorination of crude oil by phase transfer catalyst in the nucleophilic substitution method, and a new dechlorination reagent using hexamethyl quaternary ammonium hydroxide with two quaternary ammonium groups as phase transfer catalyst, ethylenediamine as nucleophile and ethanol as solvent was developed. The results show that the dechlorinating performances of the dechlorination reagent on the model compounds are as follows: epichlorohydrin > 1,2-dichlorobutane > 1,2-dichloroethane > 1,3-dichloropropane > 2-chloropropane > 1-chlorobutane > chloroisobutane, and the results of the reaction kinetics show that epichlorohydrin with epoxy structure has the lowest activation energy in the process of nucleophilic substitution reaction by the phase transfer catalyst which makes it easier to be removed by the dechlorination reagent. The removal rate of epichlorohydrin can reach up to 99.4%. The optimal dechlorination reagent used ethylenediamine as nucleophile, ethanol as solvent and hexamethyl quaternary ammonium hydroxide as phase transfer catalyst. The dechlorinating rate of the Iranian crude oil reached 71.6 % at the reaction temperature of 95°C, the reaction time of 90 minutes, the dechlorination reagent dosage of 1000 mg/kg and the 6:1 molar ratio of phase transfer reagent and nucleophile. In addition, the mechanism of phase transfer in nucleophilic substitution reaction of chloroalkanes is investigated in the paper.
    Study on Spray Characteristics of Dimethyl carbonate Blended Fuel in IC Engines
    Fu Wei, Zhou Kun, Liu Junya, Xie Hongxi, Li Yayun, Lu Lei, Bao Jihu, Cheng Yunlang
    2021, 23(4):  29-36. 
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    In this study, the spray characteristics of the blended fuel of biodiesel and Dimethyl carbonate were compared with those of biodiesel and diesel. The macroscopic spray characteristics parameters including spray tip penetration, maximum spray width, average spray cone angle and peak tip velocity were used to evaluate the spray characteristics of the blended fuel. The results showed that the spray tip penetration of blended fuel was lower than that of biodiesel, while the spray cone angle and maximum spray width of blended fuel were both larger than that of biodiesel. On the basis of Hiroyasu and Arai mathematical model, combined with the actual working conditions of this experiment, including the viscosity and density of the fuel physical parameters, a correct model of spray penetration was established, and the experimental results were compared.
    Influence of adding compatibilizer to SBS polymer-modified asphalt on compatibility and rheological behavior
    Dong Fuqiang, Hao Yunzhe, Yu Xin, Shi Jingtao, Chen Bei, Qin Chenglin
    2021, 23(4):  37-46. 
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    Adding compatibilizer to polymer-modified asphalt (PMA) is an effective method to improve material compatibility and performance. However, only a few studies have systematically focused on how compatibilizer can affect the performance of styrene-butadiene-styrene (SBS) polymer-modified asphalt (PMA). In this study, six compatibilizers with different compositions were used to prepare SBS PMA samples. Conventional performance, viscosity-temperature characteristics, viscoelastic behavior, creep properties, and morphology were investigated. The results show that adding compatibilizer to SBS PMA has a great effect on performance. High aromatics content in compatibilizers improve the high-temperature performance of SBS PMA, while a high saturates content increases low-temperature performance. Additionally, a high aromatics compatibilizer increases temperature sensitivity. While the aromatics content improves the compatibility of SBS PMA to some extent, adding compatibilizer to SBS PMA has few effects on microstructure. From our results, we can conclude that the optimum aromatics content for adding compatibilizer to SBS PMA is from 33.21 wt% to 54.22 wt%.
    Biochar Supported Nanoscale Zero-valent Iron Composites for The Removal of Petroleum
    Qin Feifei, Xu Wenfei, Hao Boyu, Yin Linghao, Song Jiayu, Zhang Xiuxia
    2021, 23(4):  47-57. 
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    In the process of oilfield exploitation, the extensive use of chemical agents leads to serious crude oil emulsification, which makes the produced liquid contain a large amount of crude oil that is difficult to remove. In order to treat oily wastewater efficiently, quickly and without secondary pollution, nanoscale zero-valent iron (nZVI) was supported on biochar prepared from spent mushroom substrate (SMS) to prepare a novel iron-carbon composite (SMS-nZVI), and its ability to treat high concentration of oily wastewater was comprehensively evaluated. The results of the indoor simulated removal of petroleum experiment show that, compared with SMS and nZVI, SMS-nZVI can remove petroleum quickly and effectively. Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) nitrogen-adsorption and Fourier transform infrared (FTIR) were used to characterize the morphology, structure and properties of the composite. The results showed that SMS biochar can effectively prevent the agglomeration of nZVI, increase the overall specific surface area and enhance the adsorption capacity of the composite. Comparing with other biochar substrates, it was found that the iron-carbon composits prepared by spent mushroom substrate has a better petroleum removal effect than the traditional wheat straw biochar. By optimizing the experimental conditions, an operation process with the best petroleum removal effect was obtained: when the mass ratio of nZVI to biochar was 1:5, pH was 4, and the initial concentration of petroleum was 1000mg·L-1, the petroleum removal rate could reach 95% at 5h. After exposing SMS-nZVI to air for 30 days for natural aging treatment, SMS-nZVI can still maintain an oil removal rate of more than 62%, which indicates that the composite has good stability.
    Effects of dispersed Mo-Fe catalysts on catalytic hydrothermal conversion of residue
    Tao Mengying, Hou Huandi, Dong Ming, Xu Ke
    2021, 23(4):  58-64. 
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    Replacement of precious single metal catalysts with cost-effective, highly-dispersed composite catalysts for catalytic hydrothermal conversion of residue holds tremendous promise for the residue upgrading technologies. Organic metals were added to the feed as the oil-soluble precursors, and transformed into the catalytic active phases in this work. Physical properties and structures of the composite catalysts had been investigated by X-ray fluorescence spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscope and transmission electron microscopy. The composite catalysts were found to be highly efficient in the catalytic hydrothermal conversion of both model compound and residue. Increased metal dispersion and synergistic effects of two metals played indispensable roles in such catalytic system. Results showed that under the test conditions in the article, the catalyst had the best catalytic performance when the mass ratio of molybdenum to iron was 1.5.
    Synthesis of Allyl Ethers from Allyl Chloride with Alcohols Catalyzed by Copper-Zirconium Oxide supported PdO
    Yuan Enxian, Sang Ruishi, Jian Panming
    2021, 23(4):  65-74. 
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    A series of copper-zirconium oxides with the Cu/Zr ratio ranging from 2/8 to 9/1 was synthesized by the co-precipitation method. PdO/CumZrn catalysts were prepared and applied to synthesize allyl ethers via the etherification reactions of allyl chloride with alcohols. The characterization results demonstrated that the presence of ZrO2 phase not only can facilitate the high dispersion of Pd2+, but can also favor the formation of Cu+ via the interaction between CuO and ZrO2. The catalytic performance initially increases and then falls off with the progressive increase in the Cu/Zr ratio. The superior performance with a conversion of 53.2% and a selectivity of 60.3% was achieved over the resulting PdO/Cu7Zr3 catalyst with the highest surface molar proportion of Cu+. Good catalytic activity was obtained, because the Cu+-Oα- pairs could enhance the dissociative activation of the -O-H bond in alcohols compared with Cu2+-O2- pairs, subsequently promoting the etherification reactions.
    Selective Hydrogenation of Maleic Anhydride to Succinic Anhydride over Nickel Catalyst Supported on Carbon Microspheres
    Zhou Yafen Chen Qilin Wang Qing Song Yu Zhou Limei
    2021, 23(4):  75-82. 
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    The colloidal carbon microspheres (CMS) were prepared by hydrothermal method. The nickel catalysts supported on carbon microspheres (Ni/CMS) were further prepared and were characterized by fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM) and N2 adsorption. The selective hydrogenation of maleic anhydride (MA) to succinic anhydride (SA) over the Ni/CMS catalysts was investigated. The results indicated that the Ni/CMS catalyst prepared with glucose as carbon source and calcined at 500 ○C exhibited the best performance. The hydrogen pressure, reaction temperature, and reaction time significantly influenced on the conversion of maleic anhydride in the hydrogenation. 98.4% conversion of MA and 100% selectivity to SA were achieved over the Ni/CMS catalyst in acetic anhydride solvent under the mild conditions of 90 ○C, 1.0 MPa of H2 pressure, and reaction time of 3 h.
    Lubrication Research
    Synthesis and Tribological Properties of Sodium-Ion-Exchanged α-Zirconium Phosphate
    Tian Chengguang Zhang Xiaosheng Xu Hong Dong Jinxiang
    2021, 23(4):  83-94. 
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    Sodium-ion-exchanged α-zirconium phosphate (Na-α-ZrP) was synthesized by using disodium hydrogen phosphate as sodium source, which was an efficient ion exchange way. The tribological properties of Na-α-ZrP as an additive in lithium grease were investigated by a four-ball tester and a SRV tester, respectively. The synergistic effect of Na-α-ZrP with ZDDP also be studied. Results indicate that Na-α-ZrP can effectively improve the antiwear and friction-reducing properties of lithium grease. Combined with ZDDP, grease demonstrated excellent anti-wear performance, especially under high loads. The possible wear mechanism was discussed by observing the worn surface under 3D optical profiler, scanning electron microscope (SEM), energy-dispersive spectrometry (EDS) and X-ray photoelectron spectroscopy (XPS). The simple synthetic method and superior tribological performance make the Na-α-ZrP become a potential choice for lubricant additives.
    Physicochemical and Tribological Properties of Anti-seize Thread Lubricant
    Wang Zhimin Xiang Shuo Liu Xiaoqiang Bao Yichen Shi Xiuqiang He Yan
    2021, 23(4):  95-104. 
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    Di-aromatics base oil and graphite powder, adding with viscosity index improver and anti-oxidant and rheological additive, were used to prepare a kind of anti-seize thread lubricant. Its physical chemistry properties, such as water resistance, thermal oxidation and aging properties, tribological performance were evaluated and compared with those of some commercial product. The results show that the overall the overall performance of the anti-seize thread lubricant met the level of some commercial product, and some properties such as thermal stability, anti-wear and anti-friction properties were better. It is more suitable for high temperature conditions.
    Molecular simulation of chain initiation mechanism in the oxidation of lubricant base stock
    Xia Lei Li Yan Zhang Hongmei Jiang Zhengyi Long Jun
    2021, 23(4):  105-112. 
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    Chain initiation reactions in the oxidation process of lubricant base stock molecules were studied by molecular simulations. Two ways to initiate lubricant oxidation were investigated. They were the dissociation of chemical bonds in base stock molecules and the reaction between base stock molecules and oxygen (O2), respectively. Reaction activation energies of above methods were calculated. The results show that C—C bonds are more likely to break than C—H bonds to generate free radicals by the pyrolysis of chemical bonds. The C—C bonds with tertiary carbon atoms are preferential positions to crack. However, bond dissociation energies of them are above 360 kJ/mol, which are difficult to occur under lubricant working conditions. The chain initiation is more likely to occur by the way that O2 attacks the two atoms in C—H bonds at the same time, and embeds into the C—H bond to produce hydrocarbon peroxides. And then, the O—O bond is cracked to form hydroxyl radicals and alkoxy radicals. The C—H bonds with tertiary carbon atoms are the preferential reaction sites, whose reaction activation energy is about 190.11 kJ/mol.
    Process Research
    Reaction Process of Heavy Hydrocarbon in Ebullated Bed Hydrogenation
    Wang Jianjun Tong Yujun Tao Yang Ge Hailong Meng Zhaohui
    2021, 23(4):  113-120. 
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    The properties and structural changes of unconverted oil (UCO) in ebullated bed residue hydrogenation at different conversion rates were analyzed to clarify the reaction process of heavy components. Meanwhile, the processing routes of UCO, delay coking and solvent deasphalting, were investigated. The results showed that with the increase of conversion, the impurity removal rate increased; meanwhile the contents of sulfur and metal in UCO decreased, while the contents of nitrogen and residual carbon increased, and the colloidal stability of UCO became worse. The structural parameters of UCO indicated that the change of heavy oil molecular structure was mainly opening of cycloalkanes ring, hydrogenation saturation of aromatic rings and dealkylation reaction during the ebullated bed hydrogenation; the aromatic structure was basically unchanged at high conversion, mainly due to the ring opening of cycloalkanes and the fracture reaction of alkyl side chains. The coking route of UCO showed that low sulfur petroleum coke with different grades could be prepared by adjusting ebullated bed conversion to produce UCOs with different properties. The coke generating coefficient and sulfur transfer coefficient in UCO coking process were higher than those in residue coking. The properties of deasphalt oil (DAO) of UCO was significantly improved and could be used as FCC or hydrocracking feedstock. The DAO yield of UCO feedstock at high conversion was higher, and its sulfur content was lower and residual carbon value was higher.
    A Simple and Effective Method to Fabricate Separation Membranes for Dehydration of Natural Gas#br#
    2021, 23(4):  121-129. 
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    PBT/PEG1000 composite membranes were prepared by the phase inversion method and were used to dehydrate natural gas. In this study, evaporation time, coagulation bath concentration, and additives in casting solution were investigated, respectively, on the selectivity and permeability of separation membranes, and optimal conditions were found to include an evaporation time of 30 sec, an 100% PEG400-containing coagulation bath and 2% of PVA used as the additive. The H2O/CH4 selectivity reached over 3600, which is about 20 times more selective than the original membrane. It provides a simple and effective preparation method to fabricate membranes for dehydration of methane gas.
    Simulation and Optimization
    Numerical simulation of dilute phase transportation in pulse riser
    An Xiaoxi Yang Ze Qiao Yingyun Tian Yuanyu
    2021, 23(4):  130-140. 
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    To study the hydrodynamic characteristics of gas–solid-phase flow in a pulse riser, a dense discrete particle model considering particle collisions and solid volume fraction is used. The core-annular flow in the enlarged-diameter section of the pulse riser is described, which can be destroyed with a high superficial gas velocity. The particle trajectory crossing effect and particle–particle and particle–wall collisions in the reduced-diameter section of the pulse riser can also destroy the core-annular flow and enhance the gas–solid interaction. The solid volume fraction exhibits an S-type distribution at different solid mass rates. The distributions of axial velocity, radial velocity, and relative slip velocity are investigated by analyzing the simulated results at different pulse riser diameter ratios. A suitable pulse riser diameter ratio can improve the performance of the pulse riser.
    2021, 23(4):  0. 
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