Preparation and investigation of Pd doped Cu catalysts for selective hydrogenation of acetylene
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RESEARCH ARTICLE
Preparation and investigation of Pd doped Cu catalysts for selective hydrogenation of acetylene Xinxiang Cao1,2,3, Tengteng Lyu1, Wentao Xie1, Arash Mirjalili1, Adelaide Bradicich1, Ricky Huitema1, Ben W.-L. Jang (✉)1, Jong K. Keum4, Karren More4, Changjun Liu3, Xiaoliang Yan5
1 Department of Chemistry, Texas A&M University-Commerce, Commerce, TX 75429-3011, USA 2 Laboratory for Development & Application of Cold Plasma Technology, College of Chemistry and Chemical Engineering, Luoyang Normal University, Luoyang 471022, China 3 Collaborative Innovation Center of Chemical Science and Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China 4 Center for Nanophase Materials Sciences and Chemical Science Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA 5 College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024, China
© Higher Education Press and Springer-Verlag GmbH Germany, part of Springer Nature 2019
Abstract A series of PdCu bimetallic catalysts with low Cu and Pd loadings and different Cu: Pd atomic ratios were prepared by conventionally sequential impregnation (CSI) and modified sequential impregnation (MSI) of Cu and Pd for selective hydrogenation of acetylene. Characterization indicates that the supported copper (II) nitrate in the PdCu bimetallic catalysts prepared by MSI can be directly reduced to Cu metal particles due to the hydrogen spillover from Pd to Cu(NO3)2 crystals. In addition, for the catalysts prepared by MSI, Pd atoms can form PdCu alloy on the surface of metal particles, however, for the catalysts prepared by CSI, Pd tends to migrate and exist below the surface layer of Cu. Reaction results indicate that compared with CSI, the MSI method enables samples to possess preferable stability as well as comparable reaction activity. This should be due to the MSI method in favor of the formation of PdCu alloy on the surface of metal particles. Moreover, even Pd loading is super low, < 0.045 wt-% in this study, by through adjusting Cu loading to an appropriate value, attractive reactivity and selectivity still can be achieved. Keywords copper, palladium, catalysts, acetylene, selective hydrogenation
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Introduction
Ethylene as the feedstock of polyethylene production is Received October 8, 2018; accepted January 30, 2019 E-mail: [email protected]
usually obtained from steam thermal cracking of naphtha, during which acetylene is inevitably produced. Since trace amount of acetylene, even ppm level, can stoichiometrically poison the polymerization catalyst, the selective hydrogenation of acetylene to ethylene in excess ethylene is a crucial industrial process of the polyethylene industry [1‒3]. Up to now, supported palladium is still the preferred catalyst used for selective hydrogenation of acetylene to ethylene owning to its high catalytic activity. However, Pd does not inherently offer good ethylene selectivity due to Pd ensemble size and the role of carbide/hydride phases [4]. To ov
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