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Enhanced stability of Pt/Al_(2)O_(3) modified by zn promoter for catalytic dehydrogenation of ethane

Journal of Energy Chemistry 2020年第12期29卷 14-20页

作者： Xiaoyu Li Yanliang Zhou Botao Qiao Xiaoli Pan Chaojie Wang Liru Cao Lin Li Jian Lin Xiaodong Wang CAS Key Laboratory of Science and Technology on Applied Catalysis Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023LiaoningChina University of Chinese Academy of Sciences Beijing 100049China

Catalytic ethane dehydrogenation(EDH) to ethylene over Pt-based catalysts has received increasing interests in recent years as it is a potential alternative route to conventional steam cracking. However, the catalysts used in this reaction often suffer from rapid deactivation due to serious coke deposition and metal sintering. Herein, we reported the effects of zn modification on the stability of Pt/Al2 O3 for *** zn-modified sample(Ptzn2/Al2 O3) exhibits stable ethane conversion(20%) with over 95% ethylene selectivity. More importantly, it exhibits a significantly low deactivation rate of only 0.003 h-1 at 600 °C for70 h, which surpasses most of previously reported catalysts. Detailed characterizations including in situ FT-IR, ethylene adsorption microcalorimetry, and HAADF-STEM etc. reveal that zn modifier reduces the number of Lewis acid sites on the catalyst surface. Moreover, it could modify Pt sites and preferentially cover the step sites, which decrease surface energy and retard the sintering of Pt particle, then prohibiting the further dehydrogenation of ethylene to ethylidyne. Consequently, the good stability is realized due to anti-sintering and the decrease of coke formation on the Pt zn2/Al2 O3 catalyst.

关键词： Catalytic dehydrogenation of ethane Stability Ptzn/Al2O3 zn promoter Coke

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Effects of zinc on χ-Fe_(5)C_(2) for carbon dioxide hydrogenation to olefins:Insights from experimental and density function theory calculations

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Chinese Journal of Chemical Engineering 2023年第2期54卷 206-214页

作者： Xianglin Liu Minjie Xu Chenxi Cao Zixu Yang Jing Xu State Key Laboratory of Chemical Engineering East China University of Science and TechnologyShanghai 200237China Maoming Branch R&D Institute SINOPECMaoming 525000China Key Laboratory of Smart Manufacturing in Energy Chemical Process Ministry of EducationEast China University of Science and TechnologyShanghai 200237China

Production of light olefins from CO_(2), the primary greenhouse gases, is of great importance to mitigate the adverse effects of CO_(2) emission on environment and to supply the value-added products from nonpetroleum resource. However, development of robust catalyst with controllable selectivity and stability remains a challenge. Herein, we report that zn-promoted Fe catalyst can boost the stable and selective production of light olefins from CO_(2). Specifically, the zn-promoted Fe exhibits a highly stable activity and olefin selectivity over 200 h time-on-stream compared to the unpromoted Fe catalyst, primarily owing to the preservation of active χ-Fe_(5)C_(2) phase. Structural characterizations of the spent catalysts suggest that zn substantially regulates the content of iron carbide on the surface and suppresses the reoxidation of bulk iron carbide during the reaction. DFT calculations confirm that adsorption of surface carbon atoms and graphene-like carbonaceous species are not thermochemically favored on zn-promoted Fe catalyst. Carbon deposition by CAC coupling reactions of two surface carbon atoms and dehydrogenation of CH intermediate are also inhibited. Furthermore, the effects of zn on antioxidation of iron carbide were also investigated. zn favored the hydrogenation of surface adsorbed oxygen atoms to H_(2)O and the desorption of H_(2)O, which reduces the possibility of surface carbide being oxidized by the chemisorbed oxygen.

关键词： Reaction engineering χ-Fe_(5)C_(2) zn promoter Carbon dioxide Hydrogenation Density function theory

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Effects of zinc on Fe-based catalysts during the synthesis of light olefins from the Fischer-Tropsch process

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Chinese Journal of Catalysis 2016年第4期37卷 510-516页

作者：高新华张建利陈宁马清祥范素兵赵天生椿范立宁夏大学省部共建天然气转化国家重点实验室培育基地宁夏银川750021 日本富山大学工学部应用化学系

Fe‐based catalysts for the production of light olefins via the Fischer‐Tropsch synthesis were modi‐fied by adding a zn promoter using both microwave‐hydrothermal and impregnation methods. The physicochemical properties of the resulting catalysts were determined by scanning electron mi‐croscopy, the Brunauer‐Emmett‐Teller method, X‐ray diffraction, H2 temperature‐programed re‐duction and X‐ray photoelectron spectroscopy. The results demonstrate that the addition of a zn promoter improves both the light olefin selectivity over the catalyst and the catalyst stability. The catalysts prepared via the impregnation method, which contain greater quantities of surface znO, exhibit severe carbon deposition following activity trials. In contrast, those materials synthesized using the microwave‐hydrothermal approach show improved dispersion of zn and Fe phases and decreased carbon deposition, and so exhibit better CO conversion and stability.

关键词： zn promoter Fe-based catalyst Light olefin Fischer-Tropsch synthesis Microwave-hydrothermal method

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