Mechanistic Study on the Selective Oxidation of Acrolein to Acrylic Acid: Identification of the Rate‐Limiting Step via Perdeuterated Acrolein

Abstract

Gas phase oxidation of acrolein to acrylic acid on hydrothermally prepared Mo/V/W mixed oxides was investigated by isotopic labeling of acrolein. In this context, perdeuterated acrolein was synthesized for the first time and subsequently used for mechanistic studies. A clear kinetic isotopic effect (KIE) is observed referring to the α‐hydrogen‐abstraction as the rate‐determining step in the selective acrolein oxidation. Furthermore, no change in the selectivity patterns is observed due to the perdeuteration, which confirms that the α‐hydrogen‐abstraction also acts as the rate‐limiting step in the total oxidation of acrolein. Based on these KIE studies combined with additional experiments including D2O‐SSITKA and temperature‐programmed desorption, a detailed reaction mechanism for acrolein oxidation is proposed.