Controlled Prepation Of Hydroxyapatite With Different Morphology And Study On CO Catalytic Oxidation Performance

The effect of supported Ag-based catalysts on catalytic activity of CO oxidation was studied.Ag/HAP supported catalyst was synthesized with hydroxyapatite?HAP?as carrier and Ag⁰as main active component.HAP carriers with different morphologies were prepared by using the controllable morphologies of HAP carriers.XRD,TEM,UV-vis,H₂-TPR and XPS were used to characterize the catalyst and analyze the results.The main conclusions of this paper are as follows:?1?A simple one-step hydrothermal method was used to prepare Ag/HAP catalyst by changing lysine concentration and synthesizing HAP nanowires of different sizes.Ag nanoparticles were dispersed on the surface of HAP carrier by the strong interaction between Ag and HAP,so that Ag nanoparticles had better catalytic activity.The activity test found that the Ag/HAP catalyst prepared had the best performance when the lysine concentration was 0.20mol·L^-1.Under the condition of air speed of 60000 mL·?g·h?^-1,the complete conversion temperature of CO was 190 ^oC.XRD and SEM characterization results showed that lysine concentration had great influence on the structure and properties of Ag/HAP catalyst.The results of UV-vis,H₂-TPR and XPS tests showed that the active component Ag mainly existed on the HAP carrier in the form of Ag⁰ and Ag⁺,of which Ag⁰ was the main catalytic activity center,making Ag/HAP catalysts maintain a high activity in CO oxidation reaction.?2?Using urea as precipitator,a long rod HAP support an aspect ratio of 10:1 was successfully prepared by one-step hydrothermal method by adjusting urea concentration and reaction pH value.According to the analysis of XRD characterization results,HAP with high purity and good crystallinity was prepared at a urea dosage of 5.6 mol.The long rod HAP was used as the carrier to support the Ag base as the catalyst and was applied to the CO catalytic oxidation reaction,showing good catalytic activity and good stability.?3?A series of Ag/H-Z catalysts were synthesized by constant volume impregnation and different treatment methods.The results showed that Ag/H-2,which was reduced by H₂ at 300^oC after roasting in a muff furnace at 400^oC,had a good activity.Under the condition of air speed of 60000 mL·?g·h?^-1,the complete conversion temperature of CO was 170 ^oC.Moreover,after three rounds of cyclic catalysis and three days of continuous catalysis,it can still maintain good stability.The results show that this treatment can enhance the strong interaction?SMSI?between the metal and the carrier,thus increasing the active component of CO oxidation.