Article Dans Une Revue Journal of Catalysis Année : 2022

Elucidation of the reaction mechanism of indirect oxidative carbonylation of methanol to dimethyl carbonate on Pd/NaY catalyst: Direct identification of reaction intermediates

Résumé

Gas-phase indirect oxidative carbonylation of methanol to dimethyl carbonate (DMC) has been industrialized, but the reaction mechanism is still ambiguous. In this work, the reaction mechanism of DMC synthesis using a NaY zeolite catalyst doped with 1.0 wt% Pd was revealed by combining in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) results with density functional theory (DFT) calculations. Two key reaction intermediates CO* (*, a surface site) and COOCH3* were identified through the adsorption of a probe molecule of methyl chloroformate (CH3OCOCl), and characterized by steady-state, dynamic-pulse and time-resolved transient DRIFTS experiments. The CO* intermediate is predominant on the catalyst surface when the reaction reached steady-state. The DFT results also showed that the inclusion of OCH3* into CO* had the highest energy barrier of 150.1 kJ mol−1. This verified that the formation of COOCH3* is the rate-determining step for the DMC synthesis. A Langmuir-Hinshelwood mechanism including the fast formation of CO*, and rate-determining insertion of OCH3* into CO* toward generation of COOCH3* to yield DMC was proposed.

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hal-03752230 , version 1 (22-11-2023)

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Chunzheng Wang, Bin Liu, Panyue Liu, Ke Huang, Ningkun Xu, et al.. Elucidation of the reaction mechanism of indirect oxidative carbonylation of methanol to dimethyl carbonate on Pd/NaY catalyst: Direct identification of reaction intermediates. Journal of Catalysis, 2022, 412, pp.30-41. ⟨10.1016/j.jcat.2022.06.002⟩. ⟨hal-03752230⟩
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