Visible light promoted aerobic selective photo-oxidation of cyclohexene on LaCoxCu1−xO3 catalyst

Heterogeneously catalyzed liquid oxidation of olefins with O2 provides an alternative way for synthesizing high-value added chemicals. Herein, we report a straightforward urea-redox and sol-gel process for synthesizing LaCoxCu1−xO3 for aerobic photo-oxidation of cyclohexene. Our research highlights a marked increase in the proportions of Co2+ and Cu+ species in a low chemical state, as well as enhanced visible light absorption through this method. Mechanistic investigations suggest that the catalytic process, particularly with LaCo0.7Cu0.3O3, involves a radical pathway mediated by reactive oxygen species. The presence of Cu+/Co2+ species and surface oxygen vacancies is proposed to boost O2 adsorption and activation on the catalyst, facilitating the formation of 2-cyclohexene-1-hydroperoxides. Furthermore, Cu2+/Co3+ species are thought to aid in generating cyclohexene-derived radical species. The efficient aerobic oxidation of cyclohexene on LaCo0.7Cu0.3O3 catalyst relies on the formation of reactive oxygen species and carbon radicals, facilitated by its strong visible light illumination. It achieves a cyclohexene conversion of 89.4% and selectivity to cyclohex-2-ene-1-one of 72.2%, along with stable recyclability after six reuses. The creation of nano-structured LaCoxCu1−xO3 through the urea-redox and sol-gel process offers a promising avenue for the development of highly efficient catalysts for the aerobic photo-oxidation of cyclohexene to cyclohex-2-ene-1-one in the future.