ZnO-Ga_2O_3/HZSM-5分子筛催化剂对C_(3～4)烷烃芳构化反应的催化作用

Catalysis of ZnO-Ga2O3 / HZSM-5 Zeolite in Aromatization of C3～4-Hydrocarbons

用浸渍法将 Ga、 Zn以氧化物的形式负载于 HZSM- 5上 ,并研究了其对 C3～ 4烷烃芳构化的催化活性 .结果表明 ,分别加入 2 % Ga和 2 % Zn后 ,当温度为 5 2 0℃、空速为 0 .76 h- 1时 ,具有较高的催化活性和芳烃选择性 ;反应进行 10 0 h后 ,催化活性无明显降低 ,显示出对 C3～ 4烷烃芳构化良好的稳定性 .用 TPD和正丁胺 Hamm ett酸性滴定法 ,测定了催化剂的表面酸性 ,发现加入 Ga、Zn等组分后 ,催化剂的总酸量变化不大 ,而酸强度却有所增加 ;加入 Zn组分后 ,催化剂的孔径变小 ,对二甲苯选择性增加 .

The activity of HZSM\|5 with loaded oxides of Ge and Zn prepared by impregnation has been studied. The experimental results show that the catalysts have high activity and selectivity for aromatization hydrocarbons of C 3~4 \| hydrocarbons after the addition of 2% Ge and 2% Zn under the following conditions: the reaction temperature is 520 ℃ and space rate is 0.76 h -1 . The activity of the catalyst does not decrease evidently after reaction for 100 h. Thus, the catalysts show high stabilization for aromatization. The acidity of the catalyst has been characterized by temperature programmed desorption of NH 3(NH 3\|TPD) and Hammett acidity titration with butyric amine. The results show that the total acidity of the catalysts does not chang after the addition of Zn and Ga, but the acid strength increases a slightly. At the same time, it is found that the aperture of the catalyst decreases and the selectivity to p \|xylene increases after the addtion of Zn.