Study On Monolithic Catalyst For Total Oxidation Of Carbon Monoxide

Monolithic catalyst is advantageous for total oxidation of carbon monoxide. In this work, two kinds of monolithic catalyst were prepared. They are single transition metal oxide and composite oxide monolithic catalysts. First, Taguchi method is used to investigate the effects of different washcoatings, active components and their loading methods in the preparation process of the single transition metal oxide monolithic catalysts in order to achieve the optimal combination of the preparation conditions. Then, the best catalyst is doped with noble metals to improve its catalytic activity. Cobalt-Alumina composite oxides deposited on monoliths were prepared by sol/precursors coating and sol-gel coating methods. Different preparation methods are discussed thoroughly in this thesis. The physical-chemical properties of the catalysts were characterized with SEM, XRD, TPR and TEM techniques.Using CO total oxidation as probe reaction, the transition metal oxides CuOx, MnOx, CoOx monolithic catalysts prepared by impregnation and deposit-precipitation were tested in monolithic reactor. Cobalt-Alumina composite oxides deposited on the monoliths prepared by sol/precursors coating and sol-gel coating methods were also investigated for CO total oxidation. The catalyst screening results showed that CoOx/SiO2(acid) was the most promising system in the single transition metal oxides monolithic catalysts. Doping noble metals has no significant effect on the activity of the CoOx/SiO2(acid). As the composite oxides were concerned, the monolithic catalyst that was prepared from Feitknecht compound precursors showed the highest activity in the total oxidation of CO. The catalytic activity was obviously promoted compared to single transition metal oxides. In this work, different preparation methods and the activities of the catalysts are related in order to investigate the correlations of the catalyst' s structure with its activity. Meantime, the coating mechanisms are also discussed in this thesis. Finally, the monolithic catalyst is compared with the particle catalyst by testing for the CO total oxidation. The results indicate that monolithic catalyst used for catalytic oxidation is much more advantageous than particle catalyst.