文献类型：期刊文献

英文题名：Effects of zeolite particle size and internal grain boundaries on Pt/Beta catalyzed isomerization of n-pentane

作者：Ye, Guanghua[1];Sun, Yuanyuan[1];Guo, Zhongyuan[1];Zhu, Kake[1];Liu, Honglai[1];Zhou, Xinggui[1];Coppens, Marc-Olivier[2]

机构：[1]East China Univ Sci & Technol, State Key Lab Chem Engn, Shanghai 200237, Peoples R China;[2]UCL, Dept Chem Engn, London WC1E 7JE, England

年份：2018

卷号：360

起止页码：152

外文期刊名：JOURNAL OF CATALYSIS

收录：;EI(收录号：20180804820956);WOS:【SCI-EXPANDED(收录号:WOS:000428823600017)】；

基金：This work was supported by the National Natural Science Foundation of China (21706067 and 91434117), the China Postdoctoral Science Foundation (2016M600289) and the Fundamental Research Funds for the Central Universities (222201714004 and 222201718003). M.-O.C is supported by the EPSRC "Frontier Engineering" Centre for Nature Inspired Engineering (EP/K038656/1) and the UK Catalysis Hub (EP/K014706/1).

语种：英文

外文关键词：Pt/Beta; n-pentane isomerization; Zeolite particle size; Internal grain boundaries; Polycrystalline zeolite; Single-crystalline zeolite

摘要：The impact of particle size and internal grain boundaries of Beta zeolites was investigated in n-pentane isomerization over bifunctional Pt/Beta catalysts, by comparing the catalytic performance of four as synthesized Pt/Beta samples that possess an identical Pt loading (0.5 wt%), but use four distinct Beta zeolites. Three of them contain polycrystalline zeolites, consisting of nano-sized crystals with a similar size of 9-13 nm, but having different average particle sizes (i.e., 1340, 830, and 250 nm) and numerous internal grain boundaries, as found via high-resolution transmission electron microscopy. The last catalyst contains single-crystalline zeolite, with an average particle size of 225 nm, and no observed internal grain boundaries. At low reaction temperature (<578 K), the particle size and internal grain boundaries do not change the apparent activity, because activity is controlled by reaction on the acid sites of the zeolite. At high reaction temperature (>614 K), a large particle size and the presence of internal grain boundaries significantly reduce the apparent activity, because of the extended diffusion path and additional diffusion barriers, which are probably caused by a mismatch in micropore alignment and gas-zeolite interfaces at these grain boundaries. Due to the small particle size and absence of internal grain boundaries, the observed activity for single-crystalline Beta can be 60-212% higher than for polycrystalline counterparts, even though it possesses a much weaker intrinsic acidity. This shows, remarkably, that single-crystalline zeolites with less internal grain boundaries can achieve a much higher catalytic activity. (C) 2018 The Authors. Published by Elsevier Inc.