关键词: 一氧化氮, 催化, 稳定性, 氧化锡, 锆, 活性

A series of Sn_xZr_(1-x)O_2 solid solution catalysts was prepared by co-current coprecipitation method using ammonia solution as precipitation agent and calcined at 500 ℃ for 4 h in air. Among them, the sample containing SnO_2 [w (WnO_2) = 60%] showed the highest NO conversion of 71% at 350 ℃, with 1.212 * 10~(-3) NO, 1.095 * 10~(-3) C_3H_6 and 2.09% O_2 in He at a space velocity of 17000 h~(-1). In comparison, the sample SZ160E2 comprising SnO_2 [w (SnO_2) = 60%] was prepared by urea-based homogeneous precipitation method, which showed a higher NO conversion of 74% at 350 ℃. Furthermore, the catalytic performance of SZ160E2 was examined thoroughly with different concentration of oxygen and propene, or at different temperature and space velocity, and the performance under steam was studied as well. The results illuminated that Sn_x Zr_(1-x)O_2 solid solution catalysts could sustain moderate activity after calcined at a temperature above 800 ℃, at a high space velocity of 50000 h~(-1), in the presence of excess O_2 content of 8.0% (lean-burn condition) or after steam treatment for 12 h. The best C_3H_6/NO molar ratio for SZ160E2 was from 1.24 to 1.65 and in this region about 80% NO could be reduced to the harmless N_2 at 350 ℃. It was shown that Sn_xZr_(1-x)O_2 solid solution catalysts had good thermal stability and hydrothermal stability, and could be used under lean-burn conditions and a high space velocity. According to the conversion of C_3H_6 to CO_2 in NO- SCR reaction, we conclude that the combustion activity of propene was restrained and the activity for NO reduction was enhanced at the same time due to the insertion of zirconium ions into the crystal lattice of tin dioxide.

Key words: NO, CATALYSIS, STABILITY, TIN OXIDE, ZIRCONIUM, ACTIVITY