Preparation Of Homogeneous Mixed Oxide Catalysts And Its Catalytic Oxidation Performance

How to uniformly disperse the metal ions in the oxide structure has always been a problem in the preparation of the catalyst for binary or multicomponent composite metal oxide catalysts.Unfortunately,traditional technologies(such as solid phase,coprecipitation,dipping and sol-gel)do not precisely regulate the intermetallic ratio.Then it is not possible to gain insight into the intrinsic active phase and reaction of multicomponent composite metal oxides mechanism.In this paper,1,3-propanediamine is used as a ligand to complex the transition metal and the rare earth metal to form bimetallic complexes,and then the ligand is decomposed by the program heating method to obtain the homogeneous composite oxide catalyst exploring it?s catalyst properties.The main results in this paper are as follows:1.1,3-propanediamine and o-vanillin as raw materials to form 1,3-propanediamine o-vanillin Schiff base ligand,and synthesized a series of transition metal and rare earth metal bimetallic complex.And IR,UV and single crystal diffraction are used to investigate the synthesis of bimetallic complexes and the dispersibility of metal ions in the complexes.The results show that the Schiff base ligand can simultaneously complex the transition metal and the rare earth metal,and the transition metal and the rare earth metal were surrounded by Schiff base ligand molecules,nitrate ions,ethanol molecules and water and the metal ions are highly dispersed in the precursor.2.The homogeneous perovskite type composite oxide catalyst LaMO3(M=Ni,Co,Mn)was prepared by the programmed temperature method of L-M-La complex as precursor.And the catalytic combustion of methane is investigated.The texture and redox properties of the composite oxide catalysts are discussed by XRD,SEM,BET,HRTEM and H2-TPR.The results showed that the metal ion migration can be well restricted by slowly slowing the program.And the composite oxide perovskite nanocrystals with uniform and uniform size of particles were obtained.This perovskite nanocrystalline was the active site of the perovskite composite oxide catalyst while providing a large amount of high temperature reactive oxygen species,exhibiting excellent methane catalytic combustion characteristics.3.Similarly,a highly dispersed cerium-based composite oxide catalysts were constructed by Schiff base complex method.It was found that the highly dispersed oxide nanocrystals were constructed by the complexation method,but the homogeneous catalyst did not show more excellent catalytic properties than the solid catalyst prepared by the solid phase method.This indicated that the active component of the catalyst was a transition metal oxide in the cerium-based oxide system.Cerium oxide could provide a large amount of reactive oxygen species.The homogeneous cerium-based composite oxide enhanced the interaction between the transition metal M(M=Mn,Cu)and Ce,but the high dispersion of the active component of the catalyst resulted in a decrease in catalyst activity.Therefore,for the different composite oxide catalyst and oxidation reaction,the active oxygen and surface active sites were important factors affecting the reaction.