Structure and Reactivity of the Mo/ZSM-5 Dehydroaromatization Catalyst

Structure and Reactivity of the Mo/ZSM-5 Dehydroaromatization Catalyst: An Operando Computational Study

Li, G. (TU Delft ChemE/Inorganic Systems Engineering; TU Delft ChemE/Catalysis Engineering)
Vollmer, I. (TU Delft ChemE/Catalysis Engineering)
Liu, C. (TU Delft ChemE/Inorganic Systems Engineering)
Gascon, Jorge (TU Delft ChemE/Catalysis Engineering; King Abdullah University of Science and Technology)
Pidko, E.A. (TU Delft ChemE/Inorganic Systems Engineering; TU Delft ChemE/Algemeen; ITMO University)

2019

Mo/ZSM-5 is one of the most studied and efficient catalysts for the dehydroaromatization of methane (MDA), but the mechanism of its operation remains controversial. Here, we combine an ab initio thermodynamic analysis with a comprehensive mechanistic density functional theory study to address Mo-speciation in the zeolite and identify the active sites under the reaction conditions. We show that the exposure of Mo/ZSM-5 to the MDA conditions yields a range of reduced sites including mono- and binuclear Mo-oxo and Mo-carbide complexes. These sites can catalyze the MDA reaction via two alternative reaction channels, namely, the C-C coupling (ethylene) and the hydrocarbon-pool propagation mechanisms. Our calculations point toward the binuclear Mo-carbide species operating through the hydrocarbon-pool mechanism to be the most catalytically potent species. Although all other Mo sites in the activated catalyst can promote C-H activation in methane, they fail to provide a successful path to the desirable low-molecular-weight products.

computational chemistry
cooperation
heterogeneous catalysis
methane dehydroaromatization
zeolite

http://resolver.tudelft.nl/uuid:d8a41ea5-de49-4c80-a704-2deeb0b54c2c

https://doi.org/10.1021/acscatal.9b02213

2155-5435

ACS Catalysis, 9 (9), 8731-8737

Institutional Repository

journal article

© 2019 G. Li, I. Vollmer, C. Liu, Jorge Gascon, E.A. Pidko