Removal Of CO And HCHO At Room Temperature Over Au Nanocatalysts Loaded On TiO₂ Powder And Foam

In recent years, indoor air pollution is more and more serious. And the problem is widely concerned. Of all the technology to remove indoor air, chemical method has mild reaction condition and economic characteristic. And it also won’t cause secondary pollution. It’s a common used method. In this work, in order to remove indoor air pollutant CO and HCHO, first, we prepared TiO2 powder and foam, which were as the support to load Au. Their catalytic and photocatalytic activity were investigated. The main results are as follows:1. TiO2 powder was prepared by chemical vapor deposition. Then, the TiO2 powder was used as the support to prepare Au/TiO2. Both deposition-precipitation and modified incipient wetness impregnation method were used. The catalyst is used to remove CO. As the calcination temperature increases, the hydroxyl content of TiO2 powder prepared by chemical vapor deposition decreases. And the specific surface area has the similar law. When the calcination temperature is 450 ℃, anatase phase appears.Au/TiO2 was prepared by deposition-precipitation method with Na2CO3 as the precipitant. Both the calcination temperature of TiO2 and treatment temperature of the catalyst were investigated. The Au loading amount of Au/TiO2 catalysts decreases as the calcination temperature of the support increases. The Au loading rate of TiO2 powder without calcination is almost 100%. And it has the highest activity for CO oxidation. The optimal activation temperature of Au/TiO2 is 250℃.When Au/TiO2 was prepared by modified incipient wetness impregnation method, the calcination temperature of TiO2 was investigated. The catalyst has high Au loading rate. And it is almost 100%. At the same time, Au loading rate has little change as the calcination temperature of TiO2 increases. Although its high Au loading rate, the catalyst has lower CO oxidation activity.2. TiO2 foam was prepared by a templating approach. And Au/TiO2 foam was also prepared. HCHO oxidation activity was investigated.Calcination temperature 650℃ of TiO2 foam was selected firstly to investigate lighting condition and residence time in removal of HCHO under UV irradiation. The results showed that HCHO conversion with two side irradiation is 10% higher than that with one side irradiation. When the gas flow changes from 200 mL/min to 120 mL/min, HCHO conversion increases from 82.36% to 90.31%.Au/TiO2 foam was prepared by modified impregnation procedure. And it was used to remove HCHO under visible light. Finally, under the visible light irradiation with two sides, 80 mL/min of the gas flow and RH=12%(T=20℃), HCHO conversion is nearly 50%.