Highly efficient aerobic oxidation of benzyl alcohol to benzaldehyde over Mn-Ni-O catalysts

Benzaldehyde is an important intermediate in industrial production and is widely used in the fields of foods, medicines, pesticides, etc. The production of benzaldehyde via chlorination-hydrolysis or direct oxidation of toluene suffers from severe equipment corrosion and chlorine-containing by-products. Using heterogeneous transition metal oxides as catalysts, the oxidation of benzyl alcohol to benzaldehyde with molecular oxygen is favorable because of mild reaction conditions, high production efficiency, and chlorine-free products. Herein, Mn-Ni bimetallic catalysts were fabricated by a specific co-precipitation method, and the influence of catalyst composition and calcination temperature on the oxidative performance of benzyl alcohol was investigated. Under the optimized reaction conditions, the conversion of benzyl alcohol reached 65.6%, with a selectivity for 100% to the target benzaldehyde. Recycling tests showed that the prepared Mn-Ni bimetallic catalyst maintained constant activity, with no significant changes in the composition, morphology, phase, and chemical state of the elements upon catalyst recovery, demonstrating reliable stability. The synthesis of Mn-Ni bimetallic catalysts and their performance in the oxidation of benzyl alcohol can provide valuable insights for the industrial production of chloro-free benzaldehyde via the aerobic oxidation of benzyl alcohol.