Issue 12, 2022

Rhodium promoted heteropolyacid catalysts for low temperature methanol carbonylation

Abstract

Acetic acid is a valuable industrial chemical obtained by the halide-free carbonylation of methanol, for which lower cost and more durable heterogeneous noble metal catalysts are desirable. Here, we report the use of a simple and cost-effective Rh acetate (Rh(OAc)2) precursor, either alone or in combination with phosphotungstic acid (HPW), to prepare silica supported monofunctional (Rh(OAc)2/SiO2) and bifunctional (Rh(OAc)2/HPW/SiO2) catalysts for methanol carbonylation. In isolation, Rh(OAc)2 is inactive for methanol carbonylation, only exhibiting stoichiometric acetic acid production from ligand release, and a low activity at 250 °C when combined with HPW in bulk form (acidity being required to protonate methanol). However, bifunctional Rh(OAc)2/HPW/SiO2 exhibits promising catalytic performance, with a TON of 70 and >90% acetic acid selectivity for 8 h on-stream without significant deactivation. In situ XAS and in situ DRIFTS measurements indicate that CO binding is activated by water loss from the acetate dimer, with geminal dicarbonyl bonding mode stabilising Rh(OAc)2 against reductive decomposition to Rh metal during the catalytic cycle. Temperatures ≥300 °C, or high methanol concentrations trigger irreversible loss of acetate ligands and rapid deactivation through Rh reduction.

Graphical abstract: Rhodium promoted heteropolyacid catalysts for low temperature methanol carbonylation

Supplementary files

Article information

Article type
Paper
Submitted
06 رجب 1443
Accepted
22 رمضان 1443
First published
25 رمضان 1443

Catal. Sci. Technol., 2022,12, 3886-3897

Rhodium promoted heteropolyacid catalysts for low temperature methanol carbonylation

A. D. Newman, Y. Wang, S. A. Orr, K. Wilson and A. F. Lee, Catal. Sci. Technol., 2022, 12, 3886 DOI: 10.1039/D2CY00254J

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements