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Influence of Nanoscale Intimacy and Zeolite Micropore Size on the Performance of Bifunctional Catalysts for n-Heptane Hydroisomerization
ACS Catalysis ( IF 12.9 ) Pub Date : 2020-11-21 , DOI: 10.1021/acscatal.0c03138
Jogchum Oenema 1 , Justine Harmel 1 , Roxana Pérez Vélez 1 , Mark J. Meijerink 1 , Willem Eijsvogel 1 , Ali Poursaeidesfahani 2 , Thijs J.H. Vlugt 2 , Jovana Zečević 1 , Krijn P. de Jong 1
Affiliation  

In this study, Pt nanoparticles on zeolite/γ-Al2O3 composites (50/50 wt) were located either in the zeolite or on the γ-Al2O3 binder, hereby varying the average distance (intimacy) between zeolite acid sites and metal sites from “closest” to “nanoscale”. The catalytic performance of these catalysts was compared to physical mixtures of zeolite and Pt/γ-Al2O3 powders, which provide a “microscale” distance between sites. Several beneficial effects on catalytic activity and selectivity for n-heptane hydroisomerization were observed when Pt nanoparticles are located on the γ-Al2O3 binder in nanoscale proximity with zeolite acid sites, as opposed to Pt nanoparticles located inside zeolite crystals. On ZSM-5-based catalysts, mostly monobranched isomers were produced, and the isomer selectivity of these catalysts was almost unaffected with an intimacy ranging from closest to microscale, which can be attributed to the high diffusional barriers of branched isomers within ZSM-5 micropores. For composite catalysts based on large-pore zeolites (zeolite Beta and zeolite Y), the activity and selectivity benefitted from the nanoscale intimacy with Pt, compared to both the closest and microscale intimacies. Intracrystalline gradients of heptenes as reaction intermediates are likely contributors to differences in activity and selectivity. This paper aims to provide insights into the influence of the metal–acid intimacy in bifunctional catalysts based on zeolites with different framework topologies.

中文翻译:

纳米亲和力和沸石微孔尺寸对庚烷加氢异构化双功能催化剂性能的影响

在这项研究中,铂纳米粒子上的沸石/γ-Al系2 ö 3种复合物(50/50重量)的任一位于沸石或的γ-Al系2 ö 3粘合剂,特此改变沸石酸之间的平均距离(亲密度)站点和金属站点,从“最近”到“纳米”。这些催化剂的催化性能与沸石和Pt /γ-Al系的物理混合物2 ö 3个粉末,其提供位点之间的“微尺度”距离。对催化活性和选择性的若干有益效果Ñ观察庚烷加氢异构化时的Pt纳米颗粒位于所述的γ-Al 2 ö3与沸石酸位点在纳米尺度上接近的粘合剂,与位于沸石晶体内部的Pt纳米粒子相反。在基于ZSM-5的催化剂上,大多数生产单支链的异构体,并且这些催化剂的异构体选择性几乎不受影响,亲密度范围从最接近微尺度,这可以归因于ZSM-5微孔中支链异构体的高扩散势垒。 。对于基于大孔沸石(β型和Y型沸石)的复合催化剂,与最接近的和微米级亲密性相比,活性和选择性得益于Pt的纳米亲密性。庚烯作为反应中间体的晶内梯度可能是造成活性和选择性差异的原因。
更新日期:2020-12-04
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