Improvement of low temperature carbon combustion catalyst characteristic caused by mixing Bi₂O₃ with Tl₂O₃

This study investigated the addition of various oxides to further improve the catalytic characteristics of Tl₂O₃, which offers a high carbon combustion catalytic capacity to lower the carbon combustion temperature of 660 °C by ~ 300 °C. Mixtures of carbon (2 wt%) with composite catalysts comprising 20 wt% Tl₂O₃-80wt% added oxide were analyzed using DSC. Bi₂O₃ offered the best improvement, where the exothermic peak temperatures for carbon combustion of carbon with various Tl₂O₃-x wt% Bi₂O₃ composites were lower than that of carbon with pure Tl₂O₃. Isothermal TG measurements were performed using a mixture of carbon and the Tl₂O₃‒95 wt% Bi₂O₃ composite catalyst, where a 2 wt% weight loss (i.e. removal of all carbon) was achieved above 230 °C. A porous alumina filter was coated with the composite catalyst and carbon was deposited on the filter surface. The filter was held at constant temperatures under air flow, which confirmed that carbon was completely removed at 230 °C. This study demonstrated the potential for using these composite catalysts in self-cleaning particulate filters to decompose and eliminate fine particulate matter and diesel particulate matter generated from steelworks, thermal power plants, and diesel vehicles simply using the heat of the exhaust gas in a factory flue-gas stack or vehicle muffler.