CO from vehicle exhaust emission and incomplete combustion of fossil fuels brings out environmental concerns. Meanwhile, CO in the feed gas of fuel cells is poisonous to Pt electrode, and need to be removed. CO oxidation at low temperature is an important technology for removal of CO. Co based catalysts have long been extensively studied for its high activity in CO oxidation, while factors of prepared methods, promoters and structures are main variables to improve the activity.A formic acid modified catalyst, Co3O4-CeO2, was prepared and applied in CO oxidation tests. The Co3O4-CeO2-0.5 catalyst, treated by formic acid at 0.5 mol/L, performed better in CO oxidation with T50 obtained at 69.5 oC and T100 obtained at 150 oC, respectively. The characterization results indicate that the Co3O4-CeO2 catalysts have small particle size and after treating with formic acid, there is a more porous structure; meanwhile, despite of the slightly decreased content of Co, there are more adsorption sites exposed by acid treatment, as suggested by CO-TPD and H2-TPD, which explains the improvement of catalytic performance.To improve the catalytic activity of Co3O4, Co3O4-Fe3O4/In2O3 catalysts were prepared with doping of Fe3O4 and In2O3, and then tested in CO oxidation. The result shows that with molar ratio of Co3O4-Fe3O4:In2O3 at 12:4, T50 and T100 were obtained at 114 oC and 215 oC, respectively. Characterization results indicate that the pore size and the pore volume were increased with addition of In2O3, while adsorption capacity of CO was enhanced as well. |