Solvent-free and efficiently selective oxidation of benzyl alcohol catalyzed by Pd/CeO2 materials under atmospheric oxygen

Abstract

Selective oxidation alcohol under solvent-free and atmosphere-pressure oxygen is a green and promising strategy for the synthesis of aldehydes and other carboxylic compounds. The design and preparation of efficient heterogeneous catalysts is a hot topic for the process. In this work, CeO2 materials were prepared through a convenient decomposition of Ce(NO3)3·6 H2O precursor, and then employed as supports to load Pd nanoparticles. The decomposition temperature had an important effect on the distributions of Pd0/Pd2+ and Ce3+/Ce4+ species, as well as the oxygen vacancy of Pd/CeO2 materials. In solvent-free and atmosphere-pressure conditions, Pd/CeO2 could smoothly convert benzyl alcohol (BZA) to benzaldehyde (BZL) with oxygen, and the catalytic activity was correlated with the percentage of Pd2+ and oxygen vacancy fractions. Under the reaction time of 4 h, temperature of 90 °C and 4 mL of benzyl alcohol, the conversion of BZA and selectivity to BZL were 72.6% and 96.3%, respectively. The catalyst could be reused at least five times without any significant loss in activity and had no leaching problem of catalytic sites.