The Preparation Of Palladium/nickel Loaded Cerium Oxide Materials And Its Research To Purify The Automobile Exhaust

Automobiles have become indispensable to people for walking tools,the exhaust gas CO,NOx,CH from car moving process causes great damage human survival and sustainable development of environment.Traditional automobile exhaust catalyst uses precious metals such as Pt,Pd and Rh,but because of its limited resources and expensive prices,so we want to reduce the amount of precious metals or to look for non-noble metal catalysts with good catalytic performance.Ceria has excellent oxygen storage capacity and thermal stability.And it can be also used as alternative materials of exhaust catalyst,so to modify cerium dioxide by means of doping or loading other metal becomes a research hotspot.Based on the above study,We use the cerium oxide materials as the supporter,then we load palladium or nickel on the supporter to get automobile exhaust catalyst by the method of precipitation deposit.We use CO+O2?CO+NO?CO+NO+CH as the main catalytic model to do our research,the main contents are as follows:(1)The preparation of palladium-ceria catalyst and their catalytic performance in CO reactionWith cerium nitrate as cerium source,polyvinylpyrrolidone K30 as dispersant,hexamethylenetetramine as precipitant,we use one-step hydrothermal method to synthesize ceria nanoparticles with the diameter of about 20 nm.And by changing the addition of PVP,HMT amount and reaction temperature,we get cerium dioxide carrier with good dispersion and good crystalline.Then by the method of deposition precipitation,we load nanoscale Pd particle on the CeO2 nanoparticles.Thereinto,CeO2 nanoparticles achieve the complete transformation of CO in 270 ?,and after loading Pd,Pd-CeO2 nanoparticles achieve the complete transformation of CO in 120?.In consequenc,the supported nano-catalyst show better low temperature activity in CO oxidation reaction.(2)The preparation of palladium/ceria-zirconia composite catalyst and their catalytic performance in CO+NO reactionWe use urea,ammonia,sodium carbonate as precipitant to prepare the ceria-zirconia composite,and through the characterization and analysis of XRD?TEM.Raman.BET,we finally chose the Ce0.5Zr0.5O2 solid solution by the preparation of ammonia as the carrier.Then,we adopt deposition precipitation method to prepare the loaded nanometer catalyst Pd/Ce0.5Zr0.5O2,and discuss the effect of different palladium load on catalytic performance.We also explore the effect of Pd in CO+NO catalytic reaction.Results show that the 2%wt load of palladium show the best catalytic effec,it achieves the 96%transformation of CO in 380 ? and the 100%transformation of NO in 380?.(3)The preparation of cordierite automobile exhaust catalyst and their study of three-way catalytic performanceWe synthesize cerium dioxide nanorods by hydrothermal method and load NiO on the surface of nanorods by deposition precipitation method.Then,we choose cordierite honeycomb ceramics as a skeleton of automobile exhaust catalyst,and coate modified ?-Al2O3 collosol on the surface of cordierite honeycomb ceramics.Then,we load the NiO ceria active component on the cordierite honeycomb ceramics and eventually made cordierite automobile exhaust catalyst.We simulate the car tail gas(CO+NO+C2H6)catalytic performance testing.The cordierite automobile exhaust catalyst can achieve the complete transformation of CO and NO,and it can also achieve the 95%transformation of C2H6.We think the monoblock automobile exhaust catalyst can keep the good catalytic activity of the active component,and it also has a good application prospect in the field of automobile tail gas treatment.