Unraveling the role of OH groups over CeO2 derived from methanol modification for enhancing toluene oxidation: Experimental and theoretical studies

Developing efficient catalysts for catalytic oxidation of toluene at low temperatures is challenging. Herein, the OH groups and oxygen vacancies are introduced into CeO2 by methanol modification and applied in catalytic oxidation of toluene. CeO2-T-M, one of the modified CeO2, displays the greatest catalytic activity for toluene oxidation with T90 of 235 oC. In situ characterizations and theoretical calculations show that abundant OH groups and oxygen vacancies on the CeO2-T-M are well correlated with the catalytic activity. The OH groups facilitate the adsorption and activation of gaseous oxygen into adsorbed active oxygen species (O22-) and lattice oxygen (O2-) over oxygen vacancies. And the toluene and key intermediates (benzyl alcohol, benzaldehyde, benzoate, and maleic anhydride) are more easily adsorbed and oxidized on CeO2-T-M. Meanwhile, the consumed OH groups will be regenerated with activated lattice oxygen by dehydrogenation, thus the catalytic activity and stability for toluene oxidation are enhanced over modified CeO2.

Automated summary

Developing efficient catalysts for low-temperature catalytic oxidation of toluene is challenging. In this study, CeO2 is modified with methanol to introduce OH groups and oxygen vacancies for catalytic oxidation of toluene. The modified CeO2, CeO2-T-M, shows the highest catalytic activity for toluene oxidation at a temperature of 235 oC. Abundant OH groups and oxygen vacancies on CeO2-T-M are found to be correlated with the catalytic activity, facilitating the adsorption and activation of gaseous oxygen and toluene, as well as the regeneration of consumed OH groups with activated lattice oxygen.