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Volume 188, 2016
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The curious case of zeolite–clay/binder interactions and their consequences for catalyst preparation

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Abstract

Zeolite-based catalyst bodies are commonly employed in a range of important industrial processes. Depending on the binder and shaping method chosen, vast differences in the reactivity, selectivity and stability are obtained. Here, three highly complementary micro-spectroscopic techniques were employed to study zeolite ZSM-5–binder interactions in SiO2-, Al2O3-, SiO2 : Al2O3- (2 : 1 mix) and kaolinite-bound catalyst pellets. We establish how their preparation influences the zeolite–clay/binder interactions. Using thiophene as an acid-catalyzed staining reaction, light absorbing oligomers produced in each sample were followed. To our surprise, kaolinite decreased the overall reactivity of the sample due to the phase change of the binder, creating a hard impenetrable outer layer. Aluminum migration to the zeolite was observed when Al2O3 was selected as a binder, creating additional Brønsted acid sites, which favored the formation of ring-opened thiophene oligomers compared to the larger oligomer species produced when SiO2 was used as a binder. In the latter case, the interaction of the Si–OH groups in the binder with thiophene was revealed to have a large impact in creating such large oligomer species. Furthermore, the combination of a SiO2 : Al2O3 mix as a binder enhanced the reactivity, possibly due to the creation of additional Brønsted acid sites between the two binder components during pellet preparation. It is evident that, independent of the shaping method, the intimate contact between the zeolite and binder heavily impacts the reactivity and product selectivity, with the type of binder playing a vital role.

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Publication details

The article was received on 30 Nov 2015, accepted on 02 Dec 2015 and first published on 02 Dec 2015


Article type: Paper
DOI: 10.1039/C5FD00200A
Citation: Faraday Discuss., 2016,188, 369-386
  • Open access: Creative Commons BY-NC license
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    The curious case of zeolite–clay/binder interactions and their consequences for catalyst preparation

    G. T. Whiting, A. D. Chowdhury, R. Oord, P. Paalanen and B. M. Weckhuysen, Faraday Discuss., 2016, 188, 369
    DOI: 10.1039/C5FD00200A

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