The Effect of Co-feeding Methyl Acetate on the H-ZSM5 Catalysed Methanol-to-Hydrocarbons Reaction

Abstract

The reactivity of methanol and methyl acetate mixtures over a HZSM-5 catalyst is studied over a period of 6 h at 350 °C, with small molecular weight olefins and aromatic compounds observed as reaction products. Post-reaction analysis of the catalyst shows the coke content to increase with methyl acetate content. Vibrational spectra (DRIFTS and inelastic neutron scattering, INS) indicate the major hydrocarbon species present in the coked catalysts to be methylated aromatic molecules, with INS spectra indicating a greater degree of methylation in the catalysts used with higher methyl acetate content. The greater extent of deactivation at higher methyl acetate concentrations is tentatively attributed to a diminishment of water in the zeolite cavity, which would otherwise facilitate re-generation of the active sites.

New Spectroscopic Insight into the Deactivation of a ZSM‐5 Methanol‐to‐Hydrocarbons Catalyst

“…To the best knowledge of the authors, this is the first time that vibrational spectra of this specification (energy range and resolution) for MTH catalysts operative over such a wide range of conditions have been reported. The spectra for the 300 (i) and 350 °C (ii) runs in Figure 4(a) are comparable and exhibit a similar pattern to previously reported ZSM‐5/MTH HCP INS spectra [47,56,57] . The general profile observed for both samples also closely resembles the spectrum of ZSM‐5 upon exposure to dimethyl ether at elevated temperatures [56] .…”

A Spectroscopic Paradox: The Interaction of Methanol with ZSM-5 at Room Temperature

“…To ensure consistency, the same ZSM-5 zeolite was used throughout the investigation. This particular ZSM-5 catalyst has been previously used for the MTH reaction with methanol [19], dimethyl ether [22] and methyl acetate [23] as feedstocks. As seen in the Electronic Supplementary Information (ESI) at 623 K with methanol it behaves as a conventional ZSM-5 catalyst with the products consisting of a range of methylated hydrocarbons, Figures S1-S3.…”

Neutron scattering studies of the methanol-to-hydrocarbons reaction

“…An INS study 97 explored the reactivity of methanol-MeOAc mixtures over an HZSM-5 catalyst at temperatures representative of that employed in MTH chemistry, with a focus on the effects of MeOAc on the catalyst lifetime. Fig.…”

“…The spectra are offset vertically for clarity. Reproduced from[97] under a Creative Commons Attribution 4.0 International License (CC-BY).…”