Selective catalytic reduction of NO_x with NH_3 over iron-cerium mixed oxide catalyst: Catalytic performance and characterization

摘要

BACKGROUND: Selective catalytic reduction (SCR) of NO with NH_3 has been proved to reduce nitric oxides in exhaust flue gas from coal-fired power plants. The commercial V_2O_5 -WO_3 (MoO_3)/TiO_2 catalyst has the disadvantages of high reaction temperature (573-673 K), high conversion of SO_2 to SO_3 and toxicity of vanadium pent-oxide to the environment and human health. Therefore, it is of some urgency to develop SCR catalyst, which works effectively in medium and low temperature ranges. In this study, a series of cerium-iron mixed oxide catalyst were prepared through a co-precipitation method and showed strong low-temperature SCR activity. RESULTS: The SCR activity over iron oxide was improved significantly by adding a small amount of cerium, especially the low-temperature activity. Cerium sharply increased the BET surface area and the pore volume of iron oxide, and also enhanced its oxidation activity of NO to NO_2. The NO_x conversion was improved when partial NO_2 was introduced into the flue gas. Iron oxide in catalyst was amorphous phase after adding a small amount of cerium. CONCLUSION: The SCR activity over iron oxide was improved by substituting partial Fe with Ce, and the optimized conditions for SCR with iron-cerium mixed oxide catalyst were validated in this study.