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Access to High-Molecular-Weight Polyethylenes through High Temperature Ethylene Polymerization Catalysed by Ethylene-Bridged ansa-(3-R-Cyclopentadienyl)(Fluorenyl) Zirconocene Complexes

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Chinese Journal of Polymer Science 2024年第1期42卷 42-51,I0007页

作者： Bo Li Haiyan Ma Jiling Huang Shanghai Key Laboratory of Functional Materials Chemistry and Laboratory of Organometallic Chemistry School of Chemistry and Molecular EngineeringEast China University of Science and TechnologyShanghai 200237China

A series of C1-symmetric ethylene-bridged ansa-(3-R-cyclopentadienyl)(fluorenyl) metallocene complexes(Zr: 1-5;Hf: 6) have been synthesized, characterized and investigated as catalyst precursors for the high temperature ethylene polymerization. Using methylaluminoxane(MAO) as the cocatalyst, zirconium complexes 1-5 bearing a bulky substituent on the 3-position of the cyclopendienyl ring showed high catalytic activities up to 1.48×10^(7) g PE·mol_(Zr)^(-1)·h^(-1) toward the polymerization of ethylene and afforded polyethylenes with high molecular weights(1.49×10^(5)-6.31×10^(5) g/mol), meanwhile exhibting great thermal stability at high temperatures up to 120 ℃ together with a long catalytic life time up to 2 h. By adopting low Al/Zr ratios, such as 125, polyethylenes with ultra high molecular weights up to 2.86×106 g/mol were obtained. It is worthy of noting that zirconium complexes 1-4 bearing a substituent with an aryl pendant showed temperature-dependent activities, which increased rapidly with the increase of polymerization temperature, thus weak interaction of the pendent aryl group with the cationic active center is proposed to account for the very low activities displayed at low temperatures. In contrast to zirconocene complexes 1-5, hafnocene complex 6 only displayed very low catalytic activities toward the polymerization of ethylene and afforded polyethylenes with molecular weights ten times smaller than those obtained by zirconocene complexes 1-5. Zirconocene complexes 1-5 were also able to catalyse the polymerization of propylene at high temperatures, but only afforded waxes with low molecular weights.

关键词： ansa-Metallocene Ethylene propylene Polymerization High temperature

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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 neutrality.The 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 sites.Furthermore,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 reaction.An effective catalyst should selectively activate the C–H bond but suppress the C–C cleavage.However,to prepare such a catalyst remains challenging.Chromium-based catalysts are always applied in industrial application of DHP;however,their toxic properties are harmful to the environment.In this aspect,exploring environment-friendly and sustainable catalytic systems with Cr-free is an important issue.In 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 reaction.We also present perspectives for future progress in the CO_(2)-ODHP.

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

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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 industry.Here,we reported two natural C4linkers based metal–organic frameworks(MIP-202 and MIP-203)for C_(3)H_(6)/C_(3)H_(8)separation.Adsorption isotherms and selectivity calculations were performed to study the adsorption performance for C_(3)H_(6)/C_(3)H_(8)separation.Results 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 to50.0.The 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 characterization.The 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,respectively.The 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 simulation.The cost of organic ligands for MIP-202 and MIP-203 was lower than that of organic ligands for those top-performance MOFs.Our 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

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Liquid-phase epoxidation of propylene with molecular oxygen by chloride manganese meso-tetraphenylporphyrins

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Chinese Journal of Chemical Engineering 2022年第8期35卷 61-65页

作者： Xian-Tai Zhou Ling-Ling Wang Yang Li Hong-Bing Ji Fine Chemical Industry Research Institute School of Chemical Engineering and TechnologySun Yat-sen UniversityZhuhai 519082China Fine Chemical Industry Research Institute School of ChemistrySun Yat-sen UniversityGuangzhou 510275China School of Chemical Engineering Guangdong University of Petrochemical TechnologyMaoming 525000China

propylene molecule owns two active sites,the direct epoxidation of propylene by dioxygen is still a challenge due to the limitation of selectivity.In this work,the direct liquid-phase propylene aerobic epoxidation protocol by chloride manganese meso-tetraphenylporphyrin(MnTPPCl)was developed.The conversion of propylene was 12.7%,and the selectivity towards PO(propylene oxide)reached up to 80.5%.The formation of PO was attributed to the mechanism via high-valent Mn species,which was confirmed by means of in situ UV–vis spectrum.

关键词： propylene Epoxidation Dioxygen Manganese porphyrins Liquid phase

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Manganese porphyrin-mediated aerobic epoxidation of propylene with isoprene: A new strategy for simultaneously preparing propylene epoxide and isoprene monoxide

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Chinese Chemical Letters 2023年第3期34卷 236-239页

作者： Xian-Tai Zhou Hai-Yang Yu Yang Li Hai-Bo Wu Hong-Bing Ji Fine Chemical Industry Research Institute School of Chemical Engineering and TechnologySun Yat-sen UniversityZhuhai 519082China Fine Chemical Industry Research Institute School of ChemistrySun Yat-sen UniversityGuangzhou 510275China Huizhou Research Institute Sun Yat-sen UniversityHuizhou 516081China Advanced Energy Science and Technology Guangdong Laboratory Huizhou 516003China

The direct epoxidation of propylene by O_(2) is a significant and challenging topic. The key factor for this homogeneous aerobic epoxidation is the activation of molecular oxygen under mild conditions. In this work,the aerobic epoxidation of propylene catalyzed by manganese porphyrins was achieved in the presence of isoprene. Isoprene contains an allyl methyl group, and the α-H can be easily removed to achieve the activation of molecular oxygen. The conversion of propylene was 38% and the selectivity toward propylene oxide(PO) was up to 87%. The role of isoprene was demonstrated, and a plausible mechanism was proposed. The protocol reported herein is expected to provide a strategy for the simultaneous preparation of propylene oxide and isoprene monoxide.

关键词： propylene Epoxidation Dioxygen Isoprene Metalloporphyrins

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A dual-bed catalyst for producing ethylene and propylene from syngas

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Journal of Energy Chemistry 2022年第3期31卷 190-194,I0006页

作者： Youming Ni Zhaopeng Liu Peng Tian Zhiyang Chen Yi Fu Wenliang Zhu Zhongmin Liu National Engineering Laboratory for Methanol to Olefins Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023LiaoningChina Dalian National Laboratory for Clean Energy Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023LiaoningChina University of Chinese Academy of Sciences Beijing 100049China

Ethylene and propylene(C_(2)^(–)3=)are the two most demanded olefin products,which are mainly produced by thermal and catalytic cracking of petroleum-derived hydrocarbons now[1].With the depletion of petroleum resour... 详细信息

关键词： Syngas Dual-bed Ethylene propylene SAPO-34

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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

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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

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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

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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 catalyst.The 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

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