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Nature of active phase of VO_x catalysts supported on SiBeta for direct dehydrogenation of propane to propylene

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Chinese Journal of Catalysis 2020年第2期41卷 276-285页

作者： Chong Chen Minglei Sun Zhongpan Hu Yuping Liu Shoumin Zhang Zhong-Yong Yuan National Institute for Advanced Materials School of Materials Science and EngineeringNankai UniversityTianjin 300350China Key Laboratory of Advanced Energy Materials Chemistry(Ministry of Education) Collaborative Innovation Center of Chemical Science and Engineering(Tianjin)College of ChemistryNankai UniversityTianjin 300071China

The VOx catalysts supported on dealuminated Beta zeolite(Si Beta) with varying V loadings(from 0.5 to 10 wt%) are prepared and tested for their catalytic activities in the reaction of direct dehydrogenation of propane to propylene(PDH). It is characterized that the VSi Beta catalysts possess different kinds of vanadium species on the Si Beta support, including monomeric or isolated VOx species at a low V loading, and polynuclear VOx species in different polymerization degrees at higher V loadings. The 3 VSi Beta catalyst(V loading is 3 wt%), containing isolated VOx species in monolayer, shows around 40% of propane conversion with 90% of propylene selectivity(reaction conditions: 600 o C, 4000 m L g–1 h–1) which are comparable to VSi Beta catalysts with higher V loadings. The catalytic activity exhibits a good linear relationship with the amount of generated acidic sites, which are derived from the interaction sites between VOx species and Si Beta support, and keeps stable after several regeneration cycles. Thus, as the VOx species directly contact with Si Beta support via V–O–Si bonds, a reactivity enhancement can be achieved. While, the initial valence state of V does not seem to influence the catalytic performance. Moreover, the aggregation degree of VOx species determines the propylene selectivity and deactivation rate, both of which increase as raising the V loading amount.

关键词： Propane dehydrogenation propylene VOx species SiBeta support Active sites

Research progress of CO_(2)oxidative dehydrogenation of propane to propylene over Cr-free metal catalysts

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Rare Metals 2022年第7期41卷 2129-2152页

作者： Zhong-Yu Wang Zhen-Hong He Long-Yao Li Shao-Yan Yang Meng-Xin He Yong-Chang Sun Kuan Wang Jian-Gang Chen Zhao-Tie Liu Shaanxi Key Laboratory of Chemical Additives for Industry College of Chemistry and Chemical EngineeringShaanxi University of Science and TechnologyXi’an 710021China School of Chemistry and Chemical Engineering Shaanxi Normal UniversityXi’an 710119China

CO_(2)-assisted oxidative dehydrogenation of propane(CO_(2)-ODHP)is an attractive strategy to offset the demand gap of propylene due to its potentiality of reducing CO_(2)emissions,especially under the demands of peaking CO_(2)emissions and carbon *** introduction of CO_(2)as a soft oxidant into the reaction not only averts the over-oxidation of products,but also maintains the high oxidation state of the redox-active ***,the presence of CO_(2)increases the conversion of propane by coupling the dehydrogenation of propane(DHP)with the reverse water gas reaction(RWGS)and inhibits the coking formation to prolong the lifetime of catalysts via the reverse Boudouard *** effective catalyst should selectively activate the C–H bond but suppress the C–C ***,to prepare such a catalyst remains ***-based catalysts are always applied in industrial application of DHP;however,their toxic properties are harmful to the *** this aspect,exploring environment-friendly and sustainable catalytic systems with Cr-free is an important *** this review,we outline the development of the CO_(2)-ODHP especially in the last ten years,including the structural information,catalytic performances,and mechanisms of chromium-free metal-based catalyst systems,and the role of CO_(2)in the *** also present perspectives for future progress in the CO_(2)-ODHP.

关键词： Propane Dehydrogenation propylene CO_(2) Chromium-free metals Catalytic performance

Highly selective separation of propylene/propane mixture on cost-effectively four-carbon linkers based metal-organic frameworks

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Chinese Journal of Chemical Engineering 2022年第11期51卷 126-134页

作者： Daofei Lv Junhao Xu Pingjun Zhou Shi Tu Feng Xu Jian Yan Hongxia Xi Zewei Liu Wenbing Yuan Qiang Fu Xin Chen Qibin Xia School of Environmental and Chemical Engineering Foshan UniversityFoshan 528000China School of Chemistry and Chemical Engineering South China University of TechnologyGuangzhou 510641China Sichuan Jinyuansheng New Energy Technology Co. LtdMeishan 620010China

The separation of propylene and propane is an important but challenging process,primarily achieved through energy-intensive distillation technology in the petrochemical ***,we reported two natural C4linkers based metal–organic frameworks(MIP-202 and MIP-203)for C_(3)H_(6)/C_(3)H_(8)*** isotherms and selectivity calculations were performed to study the adsorption performance for C_(3)H_(6)/C_(3)H_(8)*** show that C_(3)H_(6)/C_(3)H_(8)uptake ratios(298 K,100 kPa)for MIP-202 and MIP-203 are 2.34 and 7.4,respectively.C_(3)H_(6)/C_(3)H_(8)uptake ratio(303 K,100 k Pa)for MIP-203 is up *** mechanism for enhanced separation performance of C_(3)H_(6)/C_(3)H_(8)on MIP-203 at higher temperature(303 K)was revealed by the in situ PXRD *** adsorption selectivities of C_(3)H_(6)/C_(3)H_(8)on MIP-202 and MIP-203(298 K,100 k Pa)are 8.8 and 551.4,*** mechanism for the preferential adsorption of C_(3)H_(6)over C_(3)H_(8)in MIP-202 and MIP-203 was revealed by the Monte Carlo *** cost of organic ligands for MIP-202 and MIP-203 was lower than that of organic ligands for those top-performance *** work sets a new benchmark for C_(3)H_(6)sorbents with high adsorption selectivities.

关键词： propylene Propane Separation Gas Adsorption Metal-organic frameworks

Effects of Temperature and Catalyst to Oil Weight Ratio on the Catalytic Conversion of Heavy Oil to propylene Using ZSM-5 and USY Catalysts

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Journal of Natural Gas Chemistry 2007年第1期16卷 92-99页

作者： Xiaohong Li Chunyi Li Jianfang Zhang Chaohe Yang Honghong Shan State Key Laboratory of Heavy Oil Processing China University of Petroleum （Huadong） Dongying 257061 Shandong China

It is useful for practical operation to study the rules of production of propylene by the catalytic conversion of heavy oil in FCC （fluid catalytic cracking）. The effects of temperature and C/O ratio （catalyst to oil weight ratio） on the distribution of the product and the yield of propylene were investigated on a micro reactor unit with two model catalysts, namely ZSM-5/Al2O3 and USY/Al2O3, and Fushun vacuum gas oil （VGO） was used as the feedstock. The conversion of heavy oil over ZSM-5 catalyst can be comparable to that of USY catalyst at high temperature and high C/O ratio. The rate of conversion of heavy oil using the ZSM-5 equilibrium catalyst is lower compared with the USY equilibrium catalyst under the general FCC conditions and this can be attributed to the poor steam ability of the ZSM-5 equilibrium catalyst. The difference in pore topologies of USY and ZSM-5 is the reason why the principal products for the above two catalysts is different, namely gasoline and liquid petroleum gas （LPG）, repspectively. So the LPG selectivity, especially the propylene selectivity, may decline if USY is added into the FCC catalyst for maximizing the production of propylene. Increasing the C/O ratio is the most economical method for the increase of LPG yield than the increase of the temperature of the two model catalysts, because the loss of light oil is less in the former case. There is an inverse correlation between HTC （hydrogen transfer coefficient） and the yield of propylene, and restricting the hydrogen transfer reaction is the more important measure in increasing the yield of propylene of the ZSM-5 catalyst. The ethylene yield of ZSM-5/A1203 is higher, but the gaseous side products with low value are not enhanced when ZSM-5 catalyst is used. Moreover, for LPG and the end products, dry gas and coke, their ranges of reaction conditions to which their yields are dependent are different, and that of end products is more severe than that of LPG. So it is clear that maximizin

关键词： fluid catalytic cracking heavy oil propylene temperature catalyst to oil weight ratio ZSM-5 USY

Selective propylene epoxidation in liquid phase using highly dispersed Nb catalysts incorporated in mesoporous silicates

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Chinese Journal of Chemical Engineering 2018年第6期26卷 1278-1284页

作者： Wenjuan Yan Yuhui Wu Xiang Feng Chaohe Yang Xin Jin Jian Shen State Key Laboratory of Heavy Oil Processing College of Chemical EngineeringChina University of Petroleum Department of Environmental Science and Engineering Xiangtan University

Selective propylene epoxidation to propylene oxide(PO) with hydrogen peroxide(H_2O_2) was carried out in a catalytic semi-batch *** propylene epoxidation activity(44 h^(-1)) was observed over Nb based mesoporous silicate materials Nb-TUD-1 under mild operating *** physical and chemical properties of the Nb based silicates characterized using BET,FTIR,TPD,TEM and UV–Vis revealed that the site isolation and surface acidity are crucial for PO *** synthesis methods were investigated for their effects on PO productivity,PO selectivity and H_2O_2 utilization *** is found that Nb-TUD-1 material synthesized by the sol–gel method is more active and selective than impregnated materials for liquid phase propylene *** characterization confirms that thus synthesized Nb-TUD-1 catalysts have more Lewis acidity and less Bronsted acidity compared to the catalysts by impregnation.

关键词： propylene Epoxidation propylene oxide TUD-1 Niobium mesoporous materials

Optimization of the separation unit of methanol to propylene(MTP)process and its application

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Chinese Journal of Chemical Engineering 2019年第5期27卷 1089-1093页

作者： Zizong Wang Hongqian Liu Jiming Wang East China University of Science and Technology Shanghai 200237China China Petrochemical Corporation Beijing 100029China SINOPEC Engineering Incorporation Beijing 100101China

Based on a typical gas composition from a methanol-to-propylene (MTP) reactor, and guided by a requirement to recover both propylene and ethylene, three separation strategies are studied and simulated by using PROI1 package. These strategies are sequential separation, front-end dethanization, and front-end depropanization. The process does not involve an ethylene refrigeration system, using the separated stream as absorbent, and absorbing further the medium-pressure demethanization, and a proprietary technology by combining intercooling oil absorption and throttle expansio n. In fluences of different process streams as absorbent are studied on energy consumptions, propylene and ethylene recovery percentages, and other key-performance indicators of the separation strategies. Based on a commercial MTP plant with a methanol capacity of 1700 kt·a^-1, the simulated results show that the front-end dethanization using the C4 mixture as absorbent is the optimal separation strategy, in which the standard fuel oil consumption (a key-performance in dicator of energy con sumption) is 18.97 kt·h^-1, the total power consumption of two compressors is 22.4 MW, the propylene recovery percentage is 99.70%, and the ethylene recovery percentage is 99.70%. For a further improvement, the pre-dethanization and thermal coupling methods are applied. By using front-end pre-dethanization (partial cutting) with debutanizeroverhead, i.e. the C4 mixture, as absorbent, the power consumption of the compressors decreases to 19.9 MW, an 11% reduction compared with the clear-cutting method. The energy consumption for the dual compressors for crude gaseous product mixture and main product propylene refrigeration is 16.69 MW, 16.55% lower than that of the present MTP industrial plant with the same scale, and a total energy consumption of 20 MW for the triple compressors including product gas mixture compression, and ethylene and propylene refrigeration.

关键词： Heat integration distillation Methanol to propylene Ethylene propylene

Self-healing Behavior of Ethylene propylene Diene Rubbers Based on Ionic Association

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Chinese Journal of Polymer Science 2019年第7期37卷 700-707页

作者： Zhi-Fei Zhang Kun Yang Shu-Gao Zhao Lai-Na Guo Key Laboratory of Rubber-plastics Ministry of Education/Shandong Provincial Key Laboratory of Rubber-PlasticsQingdao University of Science & TechnologyQingdao 266042China College of Chemical Engineering and Materials Science Tianjin University of Science & TechnologyTianjin 300457China Hutchinson research centerRue Gustave NourryChalette sur Loing45120France

To meet the increasing demand for safe, environmentally friendly and high-performance smart materials, self-healing rubbers are highly desired. Here, the self-healing performance of ethylene propylene diene monomer rubber (EPDM) is reported, which was designed by graft-polymerization of zinc dimethacrylate (ZDMA) onto rubber chains to form a reversible ionic cross-linked network. Single ionic cross-linked network and dual network, combining covalent and ionic cross-links, could be tuned by controlling vulcanization process to achieve tailorable mechanical and self-healing properties. It was found that ionic cross-linked EPDM showed a recovery of more than 95% of the original mechanical strength through a healing process of 1 h at 100 °C. The covalent cross-links could improve mechanical properties but block self-healing. Adding 50 wt% liquid rubber to “dry” EPDM could effectively enhance self-healing capability of the dual cross-linked network and the healed tensile strength could reach 0.9 MPa. A compromise between mechanical performance and healing capability could be potentially tailored by controlling vulcanization process and liquid rubber content.

关键词： Ionic bond Self-healing Ethylene propylene diene rubber Dual-network

Deactivation Effect Caused by Catalyst-Cocatalyst Pre-contact in propylene Polymerization with MgCl2-supported Ziegler-Natta Catalyst

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Chinese Journal of Polymer Science 2019年第10期37卷 1023-1030,I0005页

作者： Zhen Zhang Bai-Yu Jiang Biao Zhang Zhi-Sheng Fu Zhi-Qiang Fan Ministry of Education Key Laboratory of Macromolecular Synthesis and Functionalization Department of Polymer Science and Engineering Zhejiang University

propylene slurry polymerization with a MgCl2-supported Ziegler-Natta catalyst containing internal electron donor was conducted after different durations of pre-contact of the catalyst with triethylaluminum cocatalyst. The number of active centers([C*]/[Ti])was determined by quenching the polymerization with 2-thiophenecarbonyl chloride and measuring sulfur content in the polymer. The pre-contact treatment caused selective deactivation of a part of active centers with low stereoselectivity and much lower activity in the initial stage of polymerization as compared with the polymerization run without the pre-contact stage. The active center concentration and polymerization activity decreased with prolonging of the pre-contact stage. The proportion of stereoselective active centers was increased by prolonging the pre-contact stage, so the isotacticity of produced polypropylene was enhanced. Release of active centers through catalyst particle fragmentation was significantly retarded, and the polymerization rate curve changed from decay type to induction type by the precontact treatment. In the induction period both non-stereoselective and stereoselective active centers were released and activated, resulting in gradual reduction of the polymer’s isotacticity in the first 5-10 min of polymerization. Selective deactivation of non-stereoselective active centers also took place in propylene polymerization using the catalyst without pre-contacting with the cocatalyst. In this case, the polymerization rate decayed with time after a short induction period of 2-5 min. Over reduction of the active center precursors with low stereoselectivity by triethylaluminum was considered as the reason for their deactivation during the pre-contact or the polymerization processes.

关键词： propylene Polymerization Supported Ziegler-Natta catalyst Cocatalyst Pre-contact

Effect of Sr loading on oxydehydrogenation of propane to propylene over Al_2O_3-supported V-Mo catalysts

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Journal of Energy Chemistry 2013年第5期22卷 778-782页

作者： Meilana Dharma Putra Saeed M.Al-Zahrani Ahmed E.Abasaeed Department of Chemical Engineering College of Engineering King Saud University

Incorporation of strontium into V-Mo alumina-supported catalyst enhanced its performance (increased conversion and selectivity,decreased reducibility and improved stability) in propane oxydehydrogenation to propylene.12.5% Sr loading was shown to be the optimum content to the V-Mo *** results were supported by various characterization techniques,namely,BET,XRD,SEM,FTIR and TPD.

关键词： oxydehydrogenation strontium vanadium-molybdenum oxides catalysts propane propylene loading