Zn/HZSM-5丙烷芳构化催化剂反应与再生过程的稳定性

Stability of Zn/HZSM-5 catalysts in reaction regeneration process of propane aromatization

对分别用离子交换法和浸渍法制备的 Zn/ HZSM- 5丙烷芳构化催化剂 ,进行了反应与再生过程的稳定性研究。在固定床连续流动反应器上考察了催化剂的结焦行为 ,用NH3- TPD和 TG对结焦催化剂作了酸性、结焦量的测定 ,并进行了 TEM形貌表征 ,表明催化剂上的结焦是造成失活的主要原因。 5 2 0℃下的空气烧炭并不能使催化剂恢复到初始水平 ,但催化剂的芳烃选择性有所提高 ,而失活速率明显降低 ;二次再生的催化剂同一次再生的基本保持了相同的活性和选择性。对经历了 3次反应与再生后的催化剂进行了锌含量测定 ,表明锌的流失相当缓慢。

The stability of Zn/HZSM 5 prepared by ion exchange and impregnation techniques was investigated. The catalyst reactivity for converting propane to aromatics was tested with different times on stream. The acidity and the amount of coke of the catalysts after aromatization reaction were determined by NH3 TPD and TG, and the patterns of the coking catalysts were observed by TEM. The results show the catalyst deactivation is mainly due to coke deposition. The regeneration process was carried out in air at 520℃. The activity and selectivity of the regenerated catalysts were tested after several cycles of deactivation regeneration. It was found that after the first cycle, the activity decreased, but selectivity increased a little and the rate of deactivation clearly decreased. After the second cycle, the activity, selectivity and rate of deactivation of the catalyst remained almost unchanged. The experiments also show that the catalysts zinc content decreased very little over three cycles of deactivation regeneration.