HZSM-11分子筛的催化性能及酸性质的研究

用脉冲微反方法研究了不同温度下不同硅铝比的HZSM-11分子筛上邻二甲苯异构化活性和选择性。结果表明,硅铝比增加,二甲苯异构化活性变化不大。用TPD技术研究了不同硅铝比的HZSM-11的酸性质,测得了NH₂在HZSM-11上的程脱谱。结果表明,在HZSM-11表面上有两种强度的酸中心。硅铝比增加,弱酸中心数减少,强酸中心数基本不变。

Studies on Catalytic Activity and Acidic Properties of HZSM-11 Zeolites

The catalytic activity and the catalytic selectivity for p-xylenc in the o-xylene isomerization reaction at different temperatures over HZSM-11 with different SiO₂/Al₂O₃ ratios were measured by means of the pulse technique. The results show that the catalytic activity changes a little with the increase of the SiO₂/Al₂O₃ ratio.TPDchromatograms of ammonia adsorbed on HZSM-11 were obtained. The results show that the weak acid sites of HZSM-11 decrease with increasing the SiO₂/Al₂O₃ ratio of HZSM-11 but that the strong acid sites do not change obviously, Jn addition, we also obtained the distribution of acidic strength, and the lowest acidic strength at which the o-xylene isomerization reaction takes placc.