(A) study on the one-pot synthesis of metal oxides associated with mesoporous silica and their application to environmental catalytic reactions

Abstract

Environmental catalyst has been larger in terms of the proportion of the worldwide catalyst market over decades to meet the increasingly stringent emissions regulations. The traditional area of environmental catalysis includes the treatment of gaseous emissions from vehicles and plants. The production of clean energy is also a crucial point, and one of the most promising solutions is based on the concept of catalysis. In the environmental catalysis area, transition metal oxides have been widely used and examined as an alternative of novel metals. Mesoporous silica has been widely used as good supports for metals or metal oxides due to their excellent pore structures. One-pot synthesis method associated with mesoporous silica is the one among the new approaches for synthesis of metal oxide catalysts with high surface area, which has the advantage to simplify the preparation steps. The effect of one-pot synthesis on the properties of metal oxide catalysts and their application to environmental catalysis was investigated for this purpose. One-pot synthesis methods associated with mesoporous silica and metal species, SBA route and MCM route successfully produced the copper oxide catalysts with high surface area from the formation of the mesoporous structure and the copper oxide. The surface area of the prepared copper oxides was larger than that by conventional methods (precipitation and post-impregnation). The use of the Cu citrate sol and the SBA route was the most effective to increase the surface area (121 m2/g) and reduce the crystallite size (4.4 nm) of the copper oxide, in which its crystallite size can be controlled with the pore size of the mesoporous structure. In the SBA route with Cu citrate sol, the thick wall and wide pore size of the mesoporous structure seem to inhibit the crystal growth and the acidic environment decreased the crystal growth rate. The catalytic activity of the copper oxides for toluene oxidation showed a good correlation with the...