Study On The Construction And Catalytic Performance Of Highly Efficient Catalysts For Toluene Degradation

Toluene is a typical volatile organic compound(VOCs)and an important organic chemical raw material.It is not only the key precursor of haze and ozone formation,but also has high toxicity and carcinogenicity,which seriously harms human health and ecological environment.Therefore,it is urgent to develop efficient technology to eliminate toluene.Catalytic oxidation has the advantages of high efficiency,energy saving,environmental protection and no secondary pollution,so it has become one of the most promising removal technologies.Catalyst is the core of the technology,including transition metal oxide catalyst and supported noble metal catalyst.Among them,transition metal oxide catalyst has low cost,good thermal stability,but the reaction temperature is high and the catalytic efficiency is low.Noble metal catalyst has high catalytic efficiency,but expensive price,poor stability,and esdy grow up under high temperature conditions.Therefore,in order to construct a low-cost,highly active and highly stable catalyst for degradation of toluene,the following two works were carried out:(1)Study on catalytic performance of zirconium based catalyst for degradation of toluene by atomic interfaceThe catalytic degradation of toluene was realized by constructing atomic interface with abundant defects.Zirconium-based catalysts with rich atomic interfaces were prepared by introducing cerium atoms into zirconia lattice by a simple coprecipitate method.The formation of rich Ce-O-Zr atomic interface and oxygen vacancy defect is induced.The defect atomic interface can significantly improve the catalytic performance and the migration of surface oxygen species.The theoretical calculation of DFT shows that the adsorption energy of molecular oxygen on the defective tetragonal Zr O2(011)crystal surface is very low,as well as the O-O bond length on the surface is obviously elongated,which induces the formation of highly active and highly reactive oxygen species.Compared with the undoped zirconia and the impregnated samples,the doped catalyst with rich defect interface not only has excellent catalytic activity,high specific surface reaction rate and low activation energy,but also has excellent durability,water resistance and sulfur resistance.In situ DRIFTS spectroscopy shows that the defective atomic interface can effectively improve the ring-opening ability of toluene and accelerate the reaction process,thus significantly improving the catalytic performance of toluene.(2)Study on the catalytic performance of toluene degradation by the synergistic structure of manganese and palladiumThe utilization rate of noble metal atoms and catalytic degradation efficiency of toluene were improved by constructing manganese and palladium synergistic integrated structure.Abundant defect sites were introduced on the surface of manganese oxide supported by Al2O3 nanocrystals with hydrogen reduction pretreatment.These defects can be localized anchored to the noble metal Pd to form manganese palladium synergistic monolithic catalysts.Compared with the untreated hydrogen samples,metal Pd presents highly dispersed and ultra-small cluster structure in Pd/Mn Al-H samples,and tends to anchor on manganese oxide nanoparticles,thus forming a Mn-Pd synergistic overall structure.The synergic overall structure not only induces more surface reactive oxygen species,but also has higher absorption and desorption capacity of toluene,which is conducive to catalytic degradation of toluene.The catalytic performance of toluene showed that the synergistic monolithic catalyst showed high TOF value,low surface reaction rate and low activation energy,besides had good stability and water resistance.