铜基分子筛SCR催化剂活性及NH3存储特性

Research on Catalytic Activity and NH3 Storage Characteristics of Copper-Based Zeolite SCR Catalyst

对比反应温度对大孔Cu/beta和新型小孔Cu/SSZ-13催化剂新鲜和老化样的平均反应速率、NOx转化率、NH3存储量和NH3泄漏的影响;分析了NH3存储、释放过程以及NH3存储量与瞬时NOx转化率的关系;研究了Cu/SSZ-13在空速为3×104 h-1和5×104 h-1下NH3存储特性.结果表明:温度对催化还原反应速率影响显著,空速影响次之;温度升高,两种催化剂平均反应速率升高.两种Cu基催化剂显示出相似的NH3存储、释放过程.随着温度升高或者空速增加,催化剂的饱和NH3存储量变小、饱和NH3存储时间变短;标称NOx转化率随着温度的增加而增加,随着空速增加而降低.低温下瞬时NOx转化率随着NH3存储量的增加而增加;300℃时NH3存储量对NOx转化率影响减小.两种催化剂中Cu/SSZ-13对NH3存储量依赖度更低,且水热稳定性能更优.

The influence of reaction temperature on the nitrogen oxide(NOx)average reaction rate,NOx conversion efficiency,ammonia(NH3)storage and the ammonia leaking storage capacity had been researched on fresh and aged macro-porous Cu/beta and new micro-porous Cu/SSZ-13 catalyst samples.NH3 storage and release process was also analyzed.Additionally,the relationship between NH3 storage and instantaneous NOx conversion efficiency was also studied on Cu/SSZ-13 under space velocity of 3×104 h-1 and 5×104 h-1 respectively.Compared to space velocity,the temperature has a more significant influence on the catalytic reduction reaction rate.When temperature rises,the average reaction rates of both catalysts are higher.Two kinds of Cu-based catalysts show a similar NH3 storage and release process.With temperature rising or the space velocity increasing,the saturated NH3 storage value and storage time gets smaller and shorter respectively.Meanwhile,the nominal NOx conversion rate increases and reduces with the increase of temperature and space velocity respectively.At low temperature,the instantaneous NOx conversion increases with the increase of NH3 storage;at 300℃,the effect of NH3 storage on NOx conversion decreases.Compared to Cu/beta,Cu/SSZ-13 catalysts show less rely on NH3 storage capacity and a better hydrothermal stability.