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

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 D 2 O‐SSITKA and temperature‐programmed desorption, a detailed reaction mechanism for acrolein oxidation is proposed.