The conversion of CO2 and CH4 to acetic acid over the Au-exchanged ZSM-5 catalyst: a density functional theory study

Wasinee Panjan; Jakkapan Sirijaraensre; Chompunuch Warakulwit; Piboon Pantu; Jumras Limtrakul

doi:10.1039/c2cp42066j

The conversion of CO2 and CH4 to acetic acid over the Au-exchanged ZSM-5 catalyst: a density functional theory study

Phys Chem Chem Phys. 2012 Dec 28;14(48):16588-94. doi: 10.1039/c2cp42066j. Epub 2012 Aug 20.

Authors

Wasinee Panjan¹, Jakkapan Sirijaraensre, Chompunuch Warakulwit, Piboon Pantu, Jumras Limtrakul

Affiliation

¹ Center for Petroleum, Petrochemicals, and Advanced Materials and Department of Chemistry, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand.

PMID: 22903398
DOI: 10.1039/c2cp42066j

Abstract

The direct conversion of methane and carbon dioxide to acetic acid is one of the most challenging research topics. Using the density functional theory (M06-L) the study reveals the catalytic activity of the Au(I)-ZSM-5 zeolite in this reaction. The Au(I)-ZSM-5 is represented by a 34T quantum cluster model. The activation of the C-H bond over the Au-ZSM-5 zeolite would readily take place via the homolytic σ-bond activation with an energy barrier of 10.5 kcal mol(-1), and subsequent proton transfer from the Au cation to the zeolitic oxygen, yielding the stable methyl-gold complex adsorbed on the zeolite Brønsted acid. The conversion of CO(2) on this bi-functional catalyst involves the Brønsted acid site playing a role in the protonation of CO(2) and the methyl-gold complex acting as a methylating agent. The activation energy of 52.9 kcal mol(-1) is predicted.