Research On In-situ Coating And Co-precipitation Preparation Of Catalyst For Catalytic Combustion Of VOCs

Volatile organic compounds?VOCs?have become one type of main airpollutions.Catalytic combustion is a simple,efficient and environment-friendly VOCs contol technology.Ceramic honeycomb Pd catalyst is one of the most common precious metal catalysts.However,the high-cost equipment of catalytic combustion due to expensive precious metal catalyst prevents this technology from wide application.Therefore,reducing the amount of precious metals or developing the metal oxides catalysts is a hot topic in this research field.In this dissertation,a series oflow loading of preciousmetal catalysts and Cu-Mn-Ce composite oxide catalysts were prepared by in-situcoating and co-precipitation method,the catalytic performance of catalysts were investigated on catalytic combustion of toluene,the catalysts were also characterized by BET,XRD,H₂-TPR,NH₃-TPD and Raman,the relationship between the structure and performance is discussed.?1?The monolithic carrier with Ce/Zr,Ce/Y coating were prepared by in-situcoating method,and then precious metal Pd are loaded onto the coating of Ce/Zr and Ce/Y by electrostatic adsorption technique.The catalytic activities of catalysts were investigated in the model reaction of tolunen combustion.Results show that Ce/Zr and Ce/Y coatings have high rate for the Pd ions adsorption.For example,Pd ion in the 0.15g/l H₂PdCl₄ solution could be completely adsorbed on to the coating within 10minutes.The higher ratio of Ce/Zr and Ce/Y coating will result in the faster adsorption of Pd ions.XRD,SEM and ultrasonic vibration characterizations show that coating layer of Ce-Zr and Ce-Y firmly and uniformly dispersed on the surface of cordierite.The catalysts of Pd/Ce-Zr and Pd/Ce-Y with 0.01%Pd all show good catalytic activity and thermal stability,indicating they are promised catalytic materials for industrial application.?2?Cu-Mn-Ce?CMC?ternary mixed oxides were prepared by co-precipitation method with different precipitants,and evaluated in the catalytic combustion of toluene.The results show the catalyst prepared with NaOH?CMC-NaOH?exhibits the highest catalytic activity,followed by the catalyst prepared with NH₃·H₂O,K₂CO₃,Na₂C₂O₄.The precursors of hydroxide derived from NaOH have strong interaction,and Cu,Mn ions are more easily enter the lattice of CeO₂ fluorite structure to form CeO₂ solid solution during calcinations.As a result,the structure containing with Cu-Mn mixed oxides and CeO₂ solid solution firmly enhance the mobility of active oxygen,owing to abundant defective sites on the surface,which has much benefit for catalytic combustion of toluene.