Low-cost and efficient Mn/CeO2 catalyst for photocatalytic VOCs degradation via scalable colloidal solution combustion synthesis method

Abstract

· Mesoporous Mn/CeO 2 was fabricated via a low cost and scalable method. · Toluene and ozone were efficiently degraded over Mn/CeO 2 catalyst. · The mechanism and pathway of photocatalytic toluene degradation were explored. · Ce 3+ , Mn 2+ and Mn 3+ species play key roles in toluene oxidation and ozone removal. Colloidal solution combustion synthesis (CSCS) is a simple and easy method for mass-production of crystalline nanomaterials with tunable pore structure. In this work, mesoporous Mn/CeO 2 catalysts were fabricated via CSCS method coupled with a dip-coating process and used for photocatalytic oxidation (PCO) of toluene. Under vacuum ultraviolet (VUV) irradiation, a high toluene removal efficiency of about 92% was achieved with a toluene reaction rate of about 118 μmol/g/h in a continuous flow reactor. A possible degradation pathway was proposed based on the analysis of intermediates by Fourier transform infrared photoluminescence spectra (FTIR) and GC-Mass. Hydrogen temperature-programmed reduction (H 2 -TPR), Brunauer-Emmett-Teller (BET) surface areas, photoluminescence spectra (PL) spectra and X-ray photoelectron spectroscopy (XPS) were carried out to analyze physical and chemical properties of the catalysts. Compared with Mn x Ce 1- x O 2 catalysts synthesized by one step CSCS method, Mn/CeO 2 has a higher photocatalytic activity, which is attributed to the presence of higher contents of Ce 3+ , Mn 2+ and Mn 3+ species. The presence of higher contents of these species plays a key role in the activity enhancement of toluene oxidation and ozone decomposition. This method is facile, efficient and scalable, and it may become a promising industrial application technology for catalyst synthesis in the near future.