Property and performance of red mud-based catalysts for the complete oxidation of volatile organic compounds

Red mud (RM) was assessed as a catalyst for the complete oxidation of volatile organic compounds (VOCs). The catalytic activity of RM was influenced by an acid treatment and the calcination temperature. Acid-treated RM (HRM) catalysts with a platinum loading (Pt/HRM) were prepared using a conventional impregnation method. Platinum catalysts supported on γ-Al₂O₃ (Pt/Al) were prepared for comparison. The physicochemical properties of the RM, HRM and Pt/HRM catalysts were characterized by BET analysis, ICP-AES, H₂-TPD, XRD, FTIR, SEM, and FE-TEM. The acid treatment increased the BET surface area of the RM significantly, resulting in an increase in catalytic activity. Increasing the calcination temperature from 400°C to 600°C caused a decrease in its catalytic activity. Increasing the platinum loading on HRM(400) from 0.1wt.% to 1wt.% led to an increase in the toluene conversion, which was attributed to the better redox properties. The catalytic activities of the Pt/HRM(400) catalysts were superior to those of the Pt/Al catalysts. Benzene, toluene, o-xylene, and hexane were oxidized completely over the 1wt.% Pt/HRM(400) catalyst at reaction temperatures less than 280°C. The presence of water vapor in the feed had a negative effect on the activity of the 1wt.% Pt/HRM(400) catalyst.