Selective Oxidation of p-Cymene over Mesoporous LaCoO3 by Introducing Oxygen Vacancies

Abstract

The liquid-phase catalytic oxidation of p-cymene to 4-methylacetophenone is an industrially significant reaction. However, the targeted oxidation of a specific C–H bond of p-cymene is extremely difficult due to there being many branched chains in p-cymene. In here, we designed a simple method to synthesize mesoporous LaCoO₃ catalysts with rich oxygen vacancy (O_ov) sites. The as-prepared mesoporous LaCoO₃ after 550 °C calcination (mLaCoO₃) exhibits remarkable catalytic activity for solvent-free oxidation of the p-cymene reaction, with a selectivity of over 80.1% selectivity for 4-methylacetophenone and a conversion of 50.2% for p-cymene (120 °C, 3 MPa). Besides, recycling studies have demonstrated that the mLaCoO₃ catalysts can be reused ten times in the aerobic oxidation of the p-cymene reaction without significant catalytic activity reduce. The experimental and characterization results indicated that the mesoporous structure of the catalyst is conducive to the generation of surface O_ov, which can properly facilitate ion spread during the catalytic process and afford enough O₂ for intermediate species, thus is beneficial for the generation of 4-methylacetophenone. This work demonstrates that the selectivity oxide p-cymene with an O₂ employing mLaCoO₃ catalyst is highly promising for chemical industrial applications.