Silverwood, IP; Arán, MA; González, IL; Kroner, A; Beale, AM; (2018) QENS study of methane diffusion in Mo/H-ZSM-5 used for the methane dehydroaromatisation reaction. In: Fernandez-Alonso,, Felix and Price,, David L. and Grzimek,, Veronika and Lohstroh,, Wiebke and Schneidewind, Astrid and Russina, Margarita, (eds.) Proceedings of the Joint Conference on Quasielastic Neutron Scattering and the Workshop on Inelastic Neutron Spectrometers Qens/Wins 2016: Probing Nanoscale Dynamics in Energy Related Materials. (pp. 030002-1-030002-9). AIP: Potsdam, Germany.

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Abstract

There is commercial interest in understanding the deactivation of Mo loaded H-ZSM-5 catalyst by coke fouling during the methane dehydroaromatization reaction (MDA). The effect of coke on methane diffusion inside the zeolite pores was studied by quasielastic neutron scattering (QENS) measurements on Mo/H-ZSM-5 samples reacted with methane for 0, 7, 25 and 60 min. Catalytic activity of the samples followed by mass spectrometry indicate that the induction period in which Mo species are carburized lasts for ∼9 min; after this period the material shows selectivity to aromatics. Characterization by TGA and N2physisorption suggest that practically no carbon is deposited during the induction period. The ∼2 wt % of coke formed after one hour of reaction has a negligible effect in the zeolite crystal structurebut a small effect on the micropore volume. The QENS studies show that the methane transport by jump diffusion is however not measurably affected by the accumulated coke in the samples.

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