Acrolein oxidation to acrylic acid over the MoVO_x material. Insights from DFT modeling

MoVO_x-type catalysts are very active and very selective in the commercially important oxidation of acrolein to acrylic acid. To contribute to unravelling the thus far poorly understood mechanism, we carried out hybrid DFT calculations on embedded cluster models, focusing on the so-called pentameric unit as active site. In the absence of water, we calculated a large energy span, 169 kJ mol^–1, for this transformation. After addressing the hydrolysis of the surface, we examined four scenarios of the acrolein conversion to explore the effect of water. The most favorable variant has a notably lower energy span, 146 kJ mol^–1, in line with experimental observations that indicate a strong acceleration of the catalytic transformation in the presence of water.