Insight into the deactivation mode of methanol-to-olefins conversion over SAPO-34: Coke, diffusion, and acidic site accessibility
Insight into the deactivation mode of methanol-to-olefins conversion over SAPO-34: Coke, diffusion, and acidic site accessibility
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深入了解 SAPO-34 上甲醇转化为烯烃的失活模式：焦炭、扩散和酸性位点可及性
DOI：
10.1016/j.jcat.2018.09.010
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发表时间：
2018-11-01
影响因子：
7.3
通讯作者：
Liu, Zhongmin
中科院分区：
文献类型：
--
作者：
Gao, Shushu;Xu, Shutao;Liu, Zhongmin
用多种光谱技术研究了晶粒度为7~10 pm的SAPO-34催化剂上甲醇转化为烯烃(MTO)的反应全过程。甲醇转化的反应和失活与CHA纳米笼中生成的焦炭的数量、大小和位置密切相关。用超极化(HP)Xe-129核磁共振和共聚焦荧光显微镜(CFM)技术相结合的方法揭示了这些焦炭在SAPO-34单晶中的不均匀空间分布。结合催化剂的酸性和扩散性能，在晶体壳层形成的大块焦炭增加了晶内扩散阻力，降低了失活催化剂中的可及酸位。从焦炭的形成和位置、传质的变化以及SAPO-34催化剂中Bronsted酸中心的可及性等方面介绍了MTO反应催化剂的整体失活模式。(C)2018 Elsevier Inc.保留所有权利。
The whole reaction course of methanol-to-olefins (MTO) conversion over SAPO-34 catalyst with crystal size 7-10 pm has been investigated by multiple spectroscopic techniques. The reaction and deactivation of methanol conversion are closely correlated to the amount, size, and location of coke formed in the CHA nanocages. A nonuniform spatial distribution of these coke species in the individual SAPO-34 crystals is revealed by a combination of hyperpolarized (HP) Xe-129 NMR and confocal fluorescence microscopy (CFM) techniques. Combined with acidic properties and diffusion performance, the bulky coke species formed at the shell layer of the crystals led to an increase of intracrystalline diffusion resistance and a decrease in accessible acidic sites in the deactivated catalyst. The overall catalyst deactivation mode of the MTO reaction is presented in terms of coke formation and location, mass transport variation, and accessibility of Bronsted acid sites in the SAPO-34 catalyst. (C) 2018 Elsevier Inc. All rights reserved.