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Impact of the Spatial Organization of Bifunctional Metal–Zeolite Catalysts on the Hydroisomerization of Light Alkanes
Author(s) -
Cheng Kang,
Wal Lars I.,
Yoshida Hideto,
Oenema Jogchum,
Harmel Justine,
Zhang Zhaorong,
Sunley Glenn,
Zečević Jovana,
Jong Krijn P.
Publication year - 2020
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201915080
Subject(s) - bifunctional , zeolite , platinum , catalysis , bifunctional catalyst , materials science , mordenite , chemical engineering , metal , inorganic chemistry , chemistry , organic chemistry , metallurgy , engineering
Improving product selectivity by controlling the spatial organization of functional sites at the nanoscale is a critical challenge in bifunctional catalysis. We present a series of composite bifunctional catalysts consisting of one‐dimensional zeolites (ZSM‐22 and mordenite) and a γ‐alumina binder, with platinum particles controllably deposited either on the alumina binder or inside the zeolite crystals. The hydroisomerization of n ‐heptane demonstrates that the catalysts with platinum particles on the binder, which separates platinum and acid sites at the nanoscale, leads to a higher yield of desired isomers than catalysts with platinum particles inside the zeolite crystals. Platinum particles within the zeolite crystals impose pronounced diffusion limitations on reaction intermediates, which leads to secondary cracking reactions, especially for catalysts with narrow micropores or large zeolite crystals. These findings extend the understanding of the “intimacy criterion” for the rational design of bifunctional catalysts for the conversion of low‐molecular‐weight reactants.