蜂窝陶瓷表面预处理对催化剂性能的影响

EFFECTS OF MONOLITH HONEYCOMB'S SURFACEPRE-TREATMENT ON THE CATALYTIC PERFORMANCE

应用溶胶－凝胶技术对蜂窝陶瓷载体进行涂层,以ＣＯ氧化作反应模型,考察了浸渍次数、分散剂及Ｌａ,Ｃｅ,Ｚｒ,Ｙ,Ｃｏ等组分对催化剂活性的影响,同时考察了Ｌａ２Ｏ３对催化剂耐热性能的影响．实验表明:两次浸渍的催化剂活性较高,浸渍原液中加入分散剂提高了催化剂对ＣＯ的氧化活性,使最低完全转化温度降低了１３℃左右．在Ｌａ,Ｃｅ,Ｚｒ,Ｙ,Ｃｏ等组分中,Ｃｅ是最有效的活性助剂,当ＣｅＯ２含量占Ａｌ２Ｏ３涂层的１８%时,催化剂的活性最好．而Ｌａ和Ｚｒ的加入对催化剂活性无明显作用,Ｙ和ＣＯ的加入则降低了催化剂的活性．在７００℃下７ｈ的热老化实验表明:Ｌａ２Ｏ３的加入对催化剂热稳定性无明显影响,但是,１０５０℃温度下２４ｈ热老化后的活性评价表明:Ｌａ２Ｏ３的加入对催化剂热稳定性作用显著,与未加Ｌａ２Ｏ３的催化剂相比,最低完全转化温度降低了１５℃左右．

In this paper, monolith honeycombs were coated by the sol-gel technology. Effects of impreg-nation times, dispersant and various additives such as La, Ce, Zr, Y, Co on the catalytic activi-ty were investigated. Also, the influence of La2O3 addition on the thermal stability was examined. The experimental results showed that the catalyst prepared via twice impregnation corresponded to the higher activity. The presence of the dispersant promoted the catalytic activity. Among the pro-moters concerned in this work, Ce was the most effective one. The catalyst possessed the best ac-tivity when CeO2 occupied 18wt% of Al2O3 coat. Addition of La and Zr had no clear effect on the catalytic activity. Both Co and Y incorporation played a negative role. The aging test under the treatment at 700℃for 7 hours revealed that the La2O3 addition didn't affect the thermal stability. However, La2O3 had a pronounced function for the thermal stability after a treatment at 1050℃ for 24 hours. For example, the lowest complete conversion temperature ( T100%/℃) decreased by 15℃ .