The Design Of Micron Spherical Metal Oxide Supported Metal Catalyst And Its CO Catalytic Oxidation Performance

The CO oxidation is one of the most extensively investigated reactions in the field of heterogeneous catalysis because of its importance in both environmental protection and fundamental studies.It is produced from the incomplete burning or partial oxidation of various fuels like coal,gasoline and natural gas.It is necessary to remove CO from sealing systems,CO2 lasers,CO protective mask,proton exchange membrane fuel cells and etc.CO is exactly a frequently used probe molecule for studying the catalyst structure,adsorption/desorption and reaction mechanism.The catalysts for the oxidation reaction mainly include supported noble metal catalysts and non-noble metal catalysts.The supported noble metal catalysts have attracted extensive attention due to their excellent catalytic activity,but the catalytic activity is unstable,and it is easy to agglomerate during the catalytic process,resulting in catalyst deactivation.Therefore,in recent years,scientists have focused on the modification of catalyst performance.By the structure and composition of the modified catalyst,the activity and stability of the catalyst are simultaneously improved.In this paper,the noble metal catalysts are modified by using microsphere-based metal oxides with nanosheets as the support.The main research contents are as follows:1.Using diethylenetriamine as a structure-directing agent,a titanium dioxide microsphere with a regular surface of about 23.2 nm was synthesized by a one-step solvent hydrothermal template method.A series of Pd/TiO2 catalysts with embedded structure were prepared by initial impregnation method to load uniform Pd nanoparticles and calcination at different temperatures.The experimental results show that the calcined TiO2 microsphere-supported Pd nanoparticles at 350 ? can completely convert the CO conversion rate to 100%at 80 ?,and the unique embedded structure can improve the stability of the catalyst at 80 ?.The conversion rate of 100%is maintained for 22 h,and after 168 h,the conversion rate can be maintained at about 50%.Compared with the supported Pd nanocatalyst with ordinary TiO2 as a support,the catalyst has a surface structure which is more favorable for the reaction activity.2.On the titanium dioxide microspheres synthesized above,the Pd/TiO2 catalyst is modified by the initial wet impregnation method and the trace amount of ZnO is loaded,and the ZnO promoter can greatly improve the catalytic activity of the catalyst.When the loading is 0.5%,catalytic activity is optimized to folly catalyze CO oxidation at 80 ?.As a catalytic promoter,ZnO can not only improve the dispersion of Pd particles,but also form ZnTiO3 on the surface of Ti02 to improve oxygen deficiency and interact with Pd metal and TiO2 at the same time,and ternary synergy,thereby improving the catalytic activity.