Highly efficient K-doped Mn-Ce catalysts with strong K-Mn-Ce interaction for toluene oxidation

In this study, K x -Mn-Ce catalysts prepared by sol-gel method were investigated for toluene oxidation. Compared with Mn-Ce, the catalytic performance of K x -Mn-Ce was further improved. XRD, HRTEM and Raman demonstrate that K ions enter the lattice of CeO 2 and disperse uniformly. The results of XPS, H 2 -TPR, and O 2 -TPD indicate that there is a strong interaction between K, Mn and Ce; the charge compensation effect would be induced when K ions enter the lattice of CeO 2 , which leads to more oxygen vacancies due to the generation of more Ce 3+ . Toluene-TPD shows that K-doping enhances the activation ability of toluene. Among all catalysts, K 0.1 -Mn-Ce shows the highest concentration of Mn 4+ , Ce 3+ , O sur, and redox ability, resulting in higher low-temperature catalytic activity. Additionally, the results of stability and water resistance also prove that K 0.1 -Mn-Ce catalyst possesses excellent stability and water resistance. K-doping is beneficial to the formation of more oxygen vacancies on Mn-Ce catalyst, which enhances the redox performance and promotes the catalytic oxidation of toluene at low temperature. • The impact of K species on Mn-Ce catalysts for toluene oxidation was studied. • K-doping is beneficial to enhance the catalytic performance of Mn-Ce. • K-doping enhances the interaction between Mn and Ce (the redox cycle: Mn 3+ +Ce 4+ ↔ Mn 4+ +Ce 3+ ). • K-doping is more conducive to the formation of oxygen vacancies. • Oxygen adsorption activation and the adsorption-activation of toluene both enhance the catalytic performance.