酸碱改性HZSM-5分子筛上甲醇制取均四甲苯的研究

Synthesis of durene from methanol over alkali and acid modified HZSM-5

摘要: 对HZSM-5分子筛进行"酸碱两步改性",制备得到了H(0.2)-Na-ZSM-5、H(0.5)-Na-ZSM-5、H(0.2)-K-ZSM-5和H(0.5)-K-ZSM-5四种催化剂。通过XRD、NH₃-TPD、ICP、FT-IR与Py-IR方法对催化剂进行表征,并在连续流动固定床反应装置上对催化剂进行评价。实验结果表明,H(0.2)-K-ZSM-5催化剂由于其孔径变大、弱的B酸量增多,从而提高了均四甲苯的选择性。

Abstract: Alkali and acid modified HZSM-5 molecular sieves were prepared through treating with different alkali solutions together with nitric acid of different concentrations; four catalysts, i.e. H(0.2)-Na-ZSM-5, H(0.5)-Na-ZSM-5, H(0.2)-K-ZSM-5 and H(0.5)-K-ZSM-5 were obtained. These catalysts were characterized by means of XRD, NH₃-TPD, ICP, FT-IR and Py-IR; their performance in the synthesis of durene from methanol was investigated in a fixed-bed down-flow reactor. The results showed that the highest selectivity to durene for methanol aromatization is achieved over the H(0.2)-K-ZSM-5 catalyst, which should be ascribed to its large pore size and abundant weak B acid sites arising from the alkali and acid modification.