Towards efficient Pd/Mn3O4 catalyst with enhanced acidic sites and low temperature reducibility for Benzene abatement

Abstract

The activity of supported Pd catalyst as a result of metal oxide support (zinc, titanium, copper and manganese) is explored in the abatement of C6H6 in the gas-phase. The high-activity and cost-effective catalysts were synthesized utilizing impregnation assisted biosynthesis (IB) method. NH3-TPD, XRD, H2-TPR, TEM, XPS, O2 and Benzene-TPD, SEM and in situ DRIFT were done to probe their physicochemical characteristics and predict the plausible oxidation mechanism. Pd particle size and dispersion, and support active acid sites were the determining factors for activity. These factors markedly affected the catalyst ability to generate surface active O2 species from the metal oxides lattice station and controlled the benzene absorption/desorption rates. The as-synthesized Pd/Mn3O4-O with small crystallite size, good Pd dispersion, improved acid sites, and low activation energy (Ea = 45.3 kJ/mol) showed commendable O2 transportability and activity as low as 140 °C, GHSV of 120,000 mLg−1 h−1. Its T100 at 240 °C was similar to Pd supported on TiO2 but was 20, 40 and 60 °C better than Pd/Mn3O4-C, Pd/ZnO and Pd/CuO. In situ DRIFT studies showed that the main intermediate species benzoquinone are oxidized to CO2 and H2O through the alkoxide and acid sites. Moreover, it was stable and highly resistant to H2O vapor.