MnOx dispersed on attapulgite derived Al-SBA-15: a promising catalyst for volatile organic compound combustion

Abstract

To improve the catalytic activity when utilizing metal oxides for the combustion of VOCs, Mn/Al-SBA-15 catalysts have been successfully synthesized through an emerging wetness impregnation technique involving Mn(NO₃)₂ on Al-SBA-15, which has been directly prepared from attapulgite by a hydrothermal method. Compared to Mn/SBA-15, which is prepared with TEOS as its silicon source, all the as-prepared Mn/Al-SBA-15 catalysts demonstrated enhanced catalytic performance in the oxidation of toluene. From this research, the 8% Mn/Al-SBA-15 catalyst presented the best catalytic performance, due to the high efficiency resulting from the high chemical valence of Mn⁴⁺. When the concentration of toluene was 2000 ppm, and the space velocity was 60 000 mL (g h)⁻¹, 8% Mn/Al-SBA-15 could effectively reduce the T₅₀ and T₉₀ values of toluene to 201 and 278 °C, respectively; while the 8% Mn/SBA-15 catalyst could reduce the T₅₀ and T₉₀ values of toluene to 223 and 298 °C, respectively. A systematic investigation has been conducted to reveal the synergistic effects of Al doping and manganese loading on the enhanced catalytic performance. The experiments showed impressive results, demonstrating that Al doping can not only increase the surface acidity of SBA-15, but it can also be beneficial for achieving a uniform dispersion of MnO_x on the surface and in the pores of Al-SBA-15, resulting in the enhancement of the catalytic performance.