摘要
采用溶胶-凝胶法和浸渍法制备了Pd/CeZr/TiO2/Al2O3蜂窝状金属丝网催化剂,并将其应用于在富氧条件下以丙烯选择催化还原NOx的研究.利用扫描电镜（SEM）分析了钛酸四丁酯的含量以及涂敷次数对TiO2涂层的影响,系统地考察了Pd含量、氧气浓度和空速对蜂窝状金属丝网催化剂催化性能的影响.实验结果表明,采用钛酸四丁酯的含量为20.0%的溶胶,涂敷2次,可以在金属丝网载体上氧化铝涂层表面获得均匀、无皲裂的TiO2涂层;Pd含量在0.23%-1.06%的范围内,NOx的转化率随Pd含量的增加而减小,Pd含量为0.23%时,NOx表现最高的NOx转化率;反应气体中氧气浓度从1.5%增加到6.0%,NOx的转化率随氧气浓度的增加而增大,当氧气浓度高于6.0%,NOx的转化率则随氧气浓度的增加而迅速减小;NOx的转化率随着空速的增加而降低,在高温条件下空速对转化率的影响要大于在低温条件下.
Pd/CeZr/TiO2/Al2O3 wire-mesh honeycomb catalyst was prepared by sol-gel and impregnation.Furthermore,selective catalytic reduction of NOx over Pd/CeZr/TiO2/Al2O3 wire-mesh honeycomb catalyst with propylene under lean burn condition was studied.The effects of the concentration of tetra-n-butyl titanate and dipcoat cycles on TiO2 washcoat were studied by SEM,and the effects of Pd concentration,O2 concentration and gas velocity on catalytic activity were investigated.The experimental results showed that the TiO2 washcoat on wire-mesh support is even and crack-free when the support is impregnated in 20.0% tetra-n-butyl titanate sol for 2 cycles.The NOx conversion decreases with Pd concentration increase.When Pd concentration is 0.23%,NOx conversion is highest.NOx conversion increases with oxygen concentration increase in the range of 1.5%-6.0%.However,when oxygen concentration is higher than 6.0%,NOx conversion decreases with increasing oxygen concentration.The NOx conversion decreases with gasvelocity increase and its effect is severer at high temperature than low temperature.
出处
《环境科学》
EI
CAS
CSCD
北大核心
2008年第6期1743-1748,共6页
Environmental Science
