Ethylene Carbonylation to 3-Pentanone with In Situ Hydrogen via a Water-Gas Shift Reaction on Rh/CeO2

Alkene carbonylation, in which hydrogenation plays pivotal roles, is one of the most efficient method for the production of oxygenated chemicals like aldehydes, amides, and esters, among others. In this work, using in situ produced hydrogen via a water- gas shift (WGS) reaction, selective ethylene carbonylation to 3-pentanone was achieved instead of hydroformylation to propionaldehyde with gaseous H2 on a defective ceria-supported Rh catalyst. The interface of Rh/CeO2, which consists of oxygen vacancies and positively charged Rh, activates water, CO, and ethylene and the subsequent reactions, including the WGS reaction and ethylene carbonylation. The lean hydrogen circumstance created by the WGS reaction suppresses the hydrogenation of the propionyl group and promotes its ethylation to 3-pentanone. A redox pathway was proposed for the WGS reaction based on the in situ FTIR results, and the origin of hydrogen for ethylene carbonylation is water, as confirmed by a mass spectrometry (MS) study using d2-water as one of the reactants. This work provides a promising method for heavier ketone synthesis.