Preparation Of Cerium Manganese Modified Molecular Sieve And Its Catalytic Degradation Performance For Benzene

With the spanking development of the modern industrialized society,we have been paid attention to the problem of atmospheric benzene pollution.Catalytic oxidation technology is widely used in the treatment of benzene pollution.This article mainly prepares cerium-manganese modified molecular sieve catalysts with good catalytic performance,and explores the role of supported cerium-manganese metal.First,we prepared a series of Ce/ZSM-5,Mn/ZSM-5,Ce-Mn/ZSM-5 molecular sieve catalysts by ultrasonic-vacuum-assisted equal volume impregnation method.Investigate the effect of the difference of Ce and Mn loading on the catalytic activity of benzene degradation catalyst.The results show that when the transition metal Ce loading is 10%,the Ce/ZSM-5 catalyst surface is rich in oxygen adsorption,and the T₉₀of benzene degradation reaches is 273℃.When the loading of transition metal Mn is 15%,Mn exists in the valence states of Mn³⁺and Mn⁴⁺,which enhances the redox capacity of the catalyst and exhibits good degradation activity.Meanwhile catalyst weak acid acidity can enhance.It’s T₉₀is 258℃.The preparation of the two-component Ce-Mn/ZSM-5 molecular sieve catalyst is greatly affected by the Ce-Mn molar ratio.When the Ce-Mn molar ratio is0.40-0.45,the activity of the Ce-Mn/ZSM-5 catalyst is the best.It’s T₉₀can reach220℃-240℃,because the oxygen active center provided by Ce and the acidic center formed by Mn have obvious synergy,and the catalyst shows good catalytic oxidation performance.Then,the template method was used to prepare nanoparticulate MFI molecular sieve,and the two-component Ce-Mn metal was supported on the carrier.The effects of Ce-Mn loading and Ce-Mn molar ratio on the activity of benzene degradation by the catalyst were investigated.The results show that when the Ce-Mn loading is 7%,the Ce-Mn molar ratio is 0.45,and the Ce-Mn loading is 10%,the Ce-Mn molar ratio is 0.40,they are the best,and their T₉₀are 220℃.The reason is that the transition metal Mn has its own redox,the transition metal Ce supplements the adsorbed oxygen for the catalytic reaction,and is reduced by the active oxygen species on the surface of the catalyst,so that the entire reaction process continues.