摘要
制备了300 ℃、350 ℃、400 ℃和500 ℃不同水热处理温度下的Zn/HZSM-5催化剂,并用于FCC汽油馏分的芳构化反应.考察了水热处理温度对芳构化反应性能的影响,并与吡啶吸附红外光谱(FT-IR)相关联,研究了水热处理温度对催化剂表面酸性的影响.结果表明,水热处理Zn/HZSM-5的芳构化活性稳定性得以改善, 与未经水热处理的催化剂相比,400 ℃水热处理的Zn(2%)/HZSM-5催化剂芳构化反应36 h时,芳烃质量分数仍高达74.25%.随着水热处理温度的升高, B酸酸中心数在300～400 ℃变化不大,500 ℃显著减少,L酸酸中心数升高,400 ℃达到最大值后呈降低趋势,烯烃转化率、烷烃转化率和产品芳烃含量升高,水热处理400 ℃时均达到最大值,分别为83.62%、95.44%和92.23%,表明此时B酸中心和L酸中心比例协调性最佳.
Zn/HZSM-5 catalysts for aromatization of FCC gasoline fraction were prepared by hydrothermal treatment at different temperature （from 300 ℃ to 500 ℃ ）. Influence of hydrothermal treatment temperature on aromatization behavior of the catalyst was investigated. Influence of hydrothermal treatment temperature on surface acidity of the catalyst was studied using FT-IR. The results showed that stability of the aromatization activity was enhanced by hydrothermal treatment. For Zn （2%）/HZSM-5 catalyst treated at 400 ℃, aromatics mass fraction in the product of 74.25% was attainable after reacting for 36 h. The quantity of Broensted acid sites changed little in 300-400 ℃, but decreased significantly at 500 ℃. The quantity of Lewis acid sites increased with treatment temperature, but declined after 400 ℃. Optimum amomatization results were attained over the catalyst treated at 400 ℃, with olefins conversion, alkenes conversion and mass fraction of aromatics in the product of 83.62 %, 95.44 % and 92.23 %, respectively, which means that best coordination between of Broensted and Lewis acid sites was attained at this treatment temperature.
出处
《工业催化》
CAS
2005年第11期22-25,共4页
Industrial Catalysis
