文献类型：期刊文献

英文题名：Hierarchical Silicoaluminophosphate Catalysts with Enhanced Hydroisomerization Selectivity by Directing the Orientated Assembly of Premanufactured Building Blocks

作者：Jin, Dongliang[1];Ye, Guanghua[3];Zheng, Jingwei[1];Yang, Weimin[2];Zhu, Kake[1];Coppens, Marc-Olivier[3];Zhou, Xinggui[1]

机构：[1]East China Univ Sci & Technol, Sch Chem Engn, State Key Lab Chem Engn, UNILAB, Shanghai 200237, Peoples R China;[2]SINOPEC, Shanghai Res Inst Petrochem Technol, Shanghai 201208, Peoples R China;[3]UCL, Dept Chem Engn, London WC1E 7JE, England

年份：2017

卷号：7

期号：9

起止页码：5887

外文期刊名：ACS CATALYSIS

收录：;EI(收录号：20173704157566);WOS:【SCI-EXPANDED(收录号:WOS:000410005700037)】；

基金：K.Z. is grateful for the financial support from National Natural Science Foundation of China (No. 21576082). X.Z. is sponsored by the National Natural Science Foundation of China (No. U1162112), Fundamental Research Funds for the Central Universities (No. WB 222201718003) and Financial Support from Sinopec Group (Contract No. 415063). M.-O.C. is supported by the EPSRC "Frontier Engineering" Centre for Nature Inspired Engineering (No. EP/K038656/1) and the UK Catalysis Hub (No. EP/K014706/1).

语种：英文

外文关键词：orientated assembly; hierarchical porosity; hydroisomerization; n-heptane; diffusion; silicoaluminophosphate; zeolite

摘要：The ability to generate nanoscale zeolites and direct their assembly into hierarchical structures offers a promising way to maximize their diffusion-dependent catalytic performance. Herein, we report an orientated assembly strategy to construct hierarchical architectures of silicoaluminophosphates (SAPOs) by using prefabricated nanocrystallites as a precursor. Such a synthesis is enabled by interrupting the dry gel conversion process to prepare nanocrystallites, as crystal growth is shown to proceed predominantly by particle attachment. The orientation of assembly can be controlled to form either a three-dimensional, spongelike morphology or a two-dimensional "house-of-cards" structure, by modifying the additives. Structures with a high degree of control over crystal size, shape, architecture, pore network, and acidic properties are achieved. This versatile technique avoids the more tedious and expensive templating routes that have been proposed previously. The catalytic performance for the hydroisomerization of n-heptane was evaluated for a series of Pt-supported catalysts, and a record isomer yield (79%) was attained for a catalyst with spongelike architecture. The hierarchical architecture influences isomer selectivity for two reasons: expanding the intrinsic reaction-controlled regime to be able to work at higher temperatures or conversion levels, and enhancing mass transport to reduce cracking of dibranched isomers. Such an acidity diffusivity interplay indicates that strong acidity favors isomerization operating at temperatures away from the diffusion-limited regime, while crystal size and pore connectivity are key factors for enhancing diffusion. The proposed materials offer tremendous opportunities to realize hierarchical catalyst designs that work under optimal operating conditions.