Comparison of the coupling of ethylene with acetate species and ethylene dehydrogenation on Pd–Au(100): a density functional study

Abstract

In this work, two key reactions in vinyl acetate monomer (VAM) synthesis, i.e., the coupling of ethylene with acetate species and ethylene dehydrogenation, on three different Pd–Au(100) surface configurations – the second nearest neighbors (denoted as PdsnAu), the first nearest neighbors (denoted as PdfnAu), and the fourth nearest-neighbor palladium island (denoted as PdislAu) – were studied. The energy barriers of the transition state of ethylene dehydrogenation to vinyl and the coupling of ethylene with acetate species on three different Pd–Au (100) surfaces were calculated. The influence of the surface properties of Pd–Au(100) on the reaction performance was analyzed and discussed at the microscopic level. The results reveal that on PdsnAu and PdfnAu surfaces where the coverage of the surface Pd atoms is relatively low, it is more likely for the coupling of ethylene with acetate species to occur, while on the PdislAu surface where the coverage of the surface Pd atoms is relatively high, it is more likely for ethylene dehydrogenation to happen. This work will improve the comprehension of the catalytic mechanism of Pd–Au(100) at the molecular and electronic levels and provide theoretical guidance for further application and development of efficient commercial catalysts, and the control of the reaction.