HZSM-5催化剂改性及其催化苯与低浓度乙烯反应的中试研究

Study on modification of HZSM-5 catalyst and its pilot catalytic performance for alkylation of benzene with dilute ethylene

苯与低浓度乙烯烷基化制乙苯是实现低浓度乙烯高附加值利用和增产乙苯的高效路线。通过水蒸气和柠檬酸后处理改性方法制备了改性的HZSM-5催化剂,对改性前后的HZSM-5催化剂样品进行了X射线衍射(XRD)、氮气物理吸附-脱附和氨气-程序升温脱附(NH3-TPD)表征分析,并考察了不同后处理方法改性HZSM-5催化剂的苯与低浓度乙烯烷基化反应的中试性能。结果表明,水蒸气和柠檬酸组合处理能调节催化剂的酸量和酸强度,增大催化剂的孔容和孔径,从而有效提高乙基苯选择性并抑制副反应的发生,降低二甲苯和重组分的生成;在模拟工业反应条件下,由水蒸气和柠檬酸处理改性的HZSM-5催化剂对乙基苯的选择性提高到99.0%,副产物二甲苯质量分数降低到7.7×10^(-5),具有工业化应用前景。

The alkylation of benzene with dilute ethylene to produce ethylbenzene is an efficient route to realize the value⁃added utilization of dilute ethylene and increase the production of ethylbenzene.The modified HZSM-5 catalysts were pre⁃pared by the steam and citric acid post⁃treatment.The HZSM-5 catalyst samples before and after post⁃treatment were char⁃acterized by X-ray diffraction(XRD),nitrogen physical adsorption desorption,and ammonia temperature programmed de⁃sorption(NH3-TPD).The pilot⁃scale catalytic performance for alkylation of benzene with dilute ethylene on HZSM-5 cata⁃lysts with different post⁃treatments was investigated.The results showed that the sequential steam and citric acid treatment significantly adjusted the acid amount and acid strength of the catalyst,and increased the pore volume and pore size of the catalyst,thereby effectively improving the ethyl benzene selectivity and suppressing the side reaction,and also reducing the production of xylene and heavy components.The obviously improved performance was obtained by sequential steam and cit⁃ric acid treatment on HZSM-5 catalyst,the selectivity of ethyl benzene was increased to 99.0%,and the by⁃product selectiv⁃ity of xylene was reduced to 7.7×10^(-5),which showed the prospect of industrial application.