Preparation And Catalytic Performance Of Nanoporous LaMO₃?M=Co,Fe?catalysts For CO Oxidation

Carbon monoxide is a common harmful gas,which is harmful to humans and the environment.Low temperature catalytic oxidation is one of the most common methods used to eliminate CO in industry.Therefore,the development of efficient green CO low-temperature oxidation catalysts has great practical significance.In recent years,cheap transition metal oxide catalyst has been made the concern of the majority of scientific research workers,and made by the rare earth metal elements and transition metal-perovskite type ABO₃ composite oxide catalyst has also been an unprecedented concern.ABO₃ has excellent performance in catalyzing CO application,while the catalytic activity of ABO₃ has a great relationship with the redox capacity of its B position,its crystal phase parameters and lattice oxygen content.ABO₃ also has good catalytic stability and good oxygen storage capacity,but because of its own structure and pore capacity and other defects,limiting its application in practice.In this paper,nanoporous LaCoO₃ and LaFeO₃ were prepared by adding citric acid as a complexing agent,and the nanoporous LaMO₃ was prepared by means of modern characterization method.Finally,The catalytic activity of the nanoporous catalyst for CO and the catalytic stability at the corresponding conversion temperature were tested.The final results are as follows:?1?The nanoporous LaCoO₃ perovskite type oxide catalyst has a two-dimensional orthorhombic crystal structure.The average particle size of the catalyst particles is 13nm.Nitrogen adsorption desorption indicates that the catalyst belongs to the mesoporous material and its pore size exists in the 1.7-10nm,transmission and XRD results show that the sample crystallinity is high,and has high purity.The results of catalytic performance test show that the nanoporous LaCoO₃ catalyst prepared by 11.12g polystyrene microspheres as hard template has the best catalytic effect for CO.At 210?,the complete conversion of CO is realized.The stability test shows that the catalyst can maintain their own catalytic stability in a quite long time.?2?The nanoporous LaFeO₃ sample has the orthorhombic perovskite structure,and the size of the catalyst is uniform,and the particle size of the prepared nanoporous LaFeO₃sample is about 19nm by XRD.The XRD shows that the catalyst has high purity,and the TG test shows that the catalyst has high thermal stability.Within 100h of experimental condition the catalysts are still can keep the catalytic activity of CO.and the complete transformation temperature of CO of nanoporous La FeO₃ was 80°C lower than bulk LaFeO₃ in the same test conditions.