摘要
采用一步离子交换法用稀土Ce3+(La3+)对Cu-ZSM-5分子筛改性,并在固定床反应器中进行了催化剂分解NO活性和耐氧性的实验研究.结果表明,离子交换主要发生在分子筛铝羟基和桥联羟基上,其中交换后的铝羟基为活性中心.Ce3+更易于交换到桥联羟基上,使铜离子占据活性中心,较低的交换温度和浓度有利于制备高催化活性催化剂.改性Cu-ZSM-5分子筛催化剂可以显著降低活性反应温度和提高空速,在310~390℃的温度范围内,La-Cu-ZSM-5催化剂上NO转化率均在80%以上,表现出良好的活性和较宽的反应温度范围.在O2体积含量低于9%时,Ce3+掺杂Cu-ZSM-5表现出良好的氧稳定性,NO转化率基本保持在84%.
Cu-ZSM-5 zeolites was modified by rare earth Ce^3＋（La^3＋）, adopting one-step ion exchange technique, The catalyst decomposing NO activity and oxygen resistance property were tested and studied in fixed bed reactor. The results of infrared absorption spectrum showed that the ion exchange happened mainly on the element sieve of aluminium hydroxy and bridge-hydroxy groups, in which the exchanged aluminium hydroxy group was the active center. The Ce^3＋ ion was exchanged more easily into the bridge hydroxy group so copper ion occupied the active center; and the lower exchange temperature and concentration were beneficial for preparing the catalysts of higher activity. Modification of Cu-ZSM-5 by Ce^3＋ element sieve catalyst could decrease markedly the active reaction temperature and increase space velocity. But also the NO conversion rate all approached above 80% in the temperature range of 310～390℃ on the catalyst of La-Cu-ZSM-5, showing good activity and wider reaction temperature range. The Cu-ZSM-5 mixed with Ce^3＋ showed good oxygen stability and the NO conversion rate remained basically at 84% when the volume content of oxygen was lower than 9%.
出处
《中国环境科学》
EI
CAS
CSCD
北大核心
2006年第4期395-399,共5页
China Environmental Science
基金
国家自然科学基金资助项目(50478069)
南京理工大学科研发展基金资助项目(SKF05015)
