近临界下HZSM-5催化的甲苯歧化反应

用高压观测池通过可视观测确定了苯、甲苯和对二甲苯等二元系及三元系的临界性质以及甲苯歧化反应混合物临界性质随着反应进程的变化规律；在此基础上，分别研究了近临界区以及高温下以HZSM-5为催化剂的甲苯歧化反应。结果发现，在近临界区甲苯歧化反应的对二甲苯选择性最高，随温度的升高甲苯转化率明显增加，对二甲苯选择性下降。高温下压力对对二甲苯选择性没有影响，转化率随压力升高而提高。

Toluene disproportionation over HZSM-5 under near critical conditions

The critical properties of both binary and ternary mixtures involved in the toluene disproportionation were measured by using a high-pressure view cell with visual observation. Moreover, the critical properties of the ternary mixture were determined with the compositions representing reaction proceeding extent of toluene disproportionation. Based on that, toluene disproportionation over HZSM-5 catalysts under near critical and high temperature was comparatively studied. It was found that both the catalyst stability and the selectivity of para-xylene under near critical conditions in toluene disproportionation were higher than those under high temperature. The conversion of toluene increased with the temperature, but the selectivity of para-xylene decreased with the increase of temperature. The pressure has little effect on the selectivity of para-xylene at high temperature, but the conversion of toluene increased with the pressure.