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 (Oov) 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 Oov, 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.