期刊
CATALYSIS TODAY
卷 390, 期 -, 页码 176-184出版社
ELSEVIER
DOI: 10.1016/j.cattod.2021.11.036
关键词
Core-Shell; Surface passivation; Surface acidity; Sil-1@ZSM-5; Alcohol dehydration
资金
- Ministero degli Affari Esteri e della Cooperazione Internazionale, Direzione Generale per la Promozione e la Cooperazione Culturale of Italy
- Ministry of Foreign Affairs and Intentational Cohoperation (Italy)
- Ministry of Science and Technology (China)
This paper presents a modified technique of epitaxial growth to produce core-shell catalysts coating microporous ZSM-5 with a layer of Silicalite-1. The aim is to passivate the surface acidity of ZSM-5 zeolite and improve its stability in methanol dehydration reaction to DME. The core-shell catalysts, synthetized using an as-made form core, exhibited interesting performances, resulting from a more controlled growth of the passivating layer.
A modified technique of epitaxial growth employed to produce core-shell catalysts coating microporous ZSM-5 with a layer of Silicalite-1 is presented in this paper. The aim was to passivate surface acidity of a ZSM-5 zeolite, in the view of potential limitation of surface effect generally responsible for coke formation. Core-shell catalysts have been synthesized starting from a ZSM-5 core with Si/Al = 25. Two different hydrothermal Silicalite-1 synthesis were performed: one using the ZSM-5 as made-form and the second using the ZSM-5H(+)-form as core. This allowed to investigate the effect of the organic template, filling the pores of the core, on the shell growth mechanism. Coating procedure lasted 24 h and it was repeated twice to increase Silicalite-1 thickness. All catalysts were tested for the reaction of methanol dehydration to DME in an atmospheric system at 180-240 degrees and time on stream tests were carried out to analyse the stability of the samples. Considering the catalytic performances in terms of methanol conversion, DME selectivity and deactivation, core-shell catalysts, synthetized using an as-made form core, exhibited interesting performances, resulting from a more controlled growth of the passivating layer. These materials could constitute valid option for hybrid (Metal-Zeolite) catalyst, where the reduction of surface acidity could better stabilize the metallic function.
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