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

In this study, Kx-Mn-Ce catalysts prepared by sol–gel method were investigated for toluene oxidation. Compared with Mn–Ce, the catalytic performance of Kx-Mn-Ce was further improved. X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM) and Raman analyses demonstrate that K ions enter the lattice of CeO2 and disperse uniformly. The results of X-ray photoelectron spectroscopy (XPS), H2-temperature programmed reduction (H2-TPR), and O2-temperature programmed desorption (O2-TPD) analyses 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 CeO2, which leads to more oxygen vacancies due to the generation of more Ce3+. Toluene-TPD shows that K-doping enhances the activation ability of toluene. Among all catalysts, K0.1-Mn-Ce shows the highest concentration of Mn4+, Ce3+, Osur, and redox ability, resulting in higher low-temperature catalytic activity. Additionally, the results of stability and water resistance also prove that K0.1-Mn-Ce catalyst possesses excellent stability and water resistance.