铜基SAPO-34催化剂原位合成及台架性能研究

In-Situ Preparation and Bench Performance of Copper-Based SAPO-34 Catalyst

使用磷酸三乙胺为结构引导剂与磷源,原位制备Cu/SAPO-34-z催化剂,考察其经800℃-10%-24 h条件处理前后的催化活性,结合XRD,SEM,TG,BET等表征手段分析理化特性,并进一步验证其发动机台架性能。结果表明:磷酸三乙胺制备的SAPO-34分子筛结晶度更高,比表面积达到了682 m^(2)/g,粒径集中分布在1~3μm;焙烧过程中,由于铜铵络合物分解,致使350~450℃区间内失重加剧;高温水热处理对Cu/SAPO-34-z催化剂低温活性影响较小,温度窗口由173~515℃劣化至173~445℃。台架性能测试结果显示:自制SCR样件200℃时NO_(x)转化率超过90%,220~450℃接近100%,即使空速增至60000 h^(-1),NO_(x)转化率仍超过98%;温度对氨存储量的影响远大于空速,3种空速下温升导致的降幅分别是86%,86%,57.5%;氨存储率越高,NO_(x)转化率越高,且变动幅度受温度与空速影响越低;空速越高,氨逃逸量越高;温度越高,尿素停喷前后氨逃逸量差值越小。

The Cu/SAPO-34-z catalyst was prepared in situ by using triethylamine phosphate as the structure director and phosphorus source.The catalytic activity was investigated before and after 800℃-10%-24 h treatment.The physicochemical properties were analyzed by XRD,SEM,TG and BET,and the engine bench performance was further verified.The results showed that SAPO-34 prepared with triethylamine phosphate had higher crystallinity,the specific surface area was 682 m^(2)/g,and the particle size was concentrated in 1-3μm.In the roasting process,the weight loss at 350-450℃becomes serious due to the decomposition of copper-ammonium complex.High-temperature hydrothermal treatment had little effect on the low-temperature activity of Cu/SAPO-34-z catalyst and the activity window degraded from 173-515℃to 173-445℃.The bench performance test results showed that the NO_(x) conversion of self-developed SCR samples exceeded 90%at 200℃and approached 100%at 220-450℃.Even if the space velocity increased to 60000 h^(-1),the NO_(x) conversion still exceeded 98%.The effect of temperature on ammonia storage was much greater than space velocity.The decreases caused by temperature were 86%,86%and 57.5%respectively under the three space velocities.The higher the ammonia storage,the higher the NO_(x) conversion,and the lower the influence of fluctuation range on temperature and space velocity.The higher the space velocity,the higher the ammonia escape.The higher the temperature,the smaller the difference of ammonia escape before and after stopping the urea injection.