A Study On Composite Metallic Oxides Catalyst Controlling Organic Pollutant Emission By Catalytic Combustion

People have paid much more attention to the research of catalyst of catalytic combustion for two reasons, protecting the environment and improving the efficiency of using energy. Catalytic combustion can convert the contaminated organic gas to carbon dioxide and water in relatively low temperature (mostly between 250℃to 400℃), the efficiency of eliminating can be over 95% and has been introduced to a widely applications. In this paper a series of catalysts of metallic oxides were prepared and characterized with XRD and BET.We prepared single and composite metallic oxides (included zirconium, cerium, lanthanum, cobalt, manganese, iron) by co-precipitation and hydrothermal method. The catalytic reaction activity, which varied with the active component and calcination temperature, were investigated. The results show that the catalytic activity improved when the catalysts were some kind of composite components. The activity of the catalyst is higher with lower calcination temperature. The best sample of single component catalyst is ferric oxide, which T_99% is 579℃. The optimum sample of two component is cobalt/ manganese, which T_99% is 556℃. Perovskite type catalyst show little catalytic activity. The activity of LaMnOa or LaCoOa improved when the catalyst was loaded on ZrO₂, but the activity of LaFeOa reduced after being loaded on ZrO₂. The crystal construction and surface characteristics of the catalyst were also studied with XRD and BET.The reaction conditions of hydrothermal method were studied through Orthogonal experiment, the results show that the catalyst prepared with the following process may promise higher catalytic activity. The water solution of reaction is nitrate cobalt and urea. The mol-quantity of the urea is 4.5 times than the stoichiometric amount. After reaction for 4 hours at 160℃, the deposition was washed and calcinated at 500℃for 3 hours. The experiment designed with orthogonal method show that the activity of catalyst improves significantly, which the T_10% and T_99% is 271℃and 447℃. The activity of catalyst increased with the increase hydrothermal reaction temperature and urea concentration in the experimental range. The activity of two components catalyst prepared with hydrothermal method is lower than single component catalyst prepared with the same method. No solid solution is formed through the experiment of XRD and BET.