Study On Low Temperature Oxidation Activity And Sulfur Resistance Activity Of Non-precious Metal CDPF Catalysts Of Soot Catalytic Oxidation

CDPF-Catalytic diesel particulate capture and regeneration technology can effectively and stably remove soot particles from the exhaust gas of mobile diesel engine.The widely used precious metal CDPF catalysts such as Pt and Pd have excellent effect but high cost,and are prone to sulfur poisoning.Therefore,it is necessary to develop a low-cost non-precious metal catalyst with excellent low-temperature oxidation activity and sulfur resistance to replace precious metal catalysts.A series of CuCeZrO_2-?catalysts were prepared by loading different molar ratios of Cu on CeO₂-ZrO₂ catalyst substrates.The best catalyst was Cu_0.9Ce_0.05Zr_0.05O_2-?by activity test.The maximum oxidation rate temperatures of carbon particles of the catalyst and commercial Pt catalyst were 374 and 506?respectively,which indicated that the catalyst could replace precious metal catalysts in the exhaust temperature range of 150-400?.Carbon soot particles were efficiently oxidized by chemicals.The results show that the maximum soot particle oxidation rate temperature of CuCeZrO_2-?series catalysts and commercial Pt catalysts increases by 50 and 100?on average,so the sulfur resistance of CuCeZrO_2-?series catalysts is better than that of commercial Pt catalysts.Partial substitution of transition metal La for Cu was used to further improve the sulfur resistance of the catalyst.It was found that the activity of the catalyst after pre-sulfurization and sulfur-containing conditions was almost no attenuation compared with that of the fresh catalyst.The catalyst formulated as La_0.1Cu_0.8Ce_0.05Zr_0.05O_2-?had comprehensive optimal sulfur resistance and low temperature smoke oxidation activity.XPS,XRD,TEM and in situ diffuse reflectance infrared spectroscopy were used to study the physicochemical properties of the catalyst and the reaction process on the surface of the catalyst.It was found that CuCeZrO_2-?catalyst had high specific surface area and good grain dispersion.It mainly relied on the strong oxidation of copper to promote the oxidation of NO and produce NO₂ to oxidize soot.The main element affected by sulfur poisoning is copper.Under sulfur-containing conditions,the addition of La can inhibit the sulfur poisoning of copper in the catalyst,so that there are still more active sites on the catalyst surface.