HZSM-5分子筛改性对烃类裂解及芳构化性能的影响——Ⅱ.镍改性HZSM-5分子筛的研究

EFFECT OF MODIFICATION OF HZSM-5 ZEOLITE ON n-HEXANE CRACKING AND AROMATIZATION——Ⅱ.STUDY OF Ni-HZSM-5

本文以正己烷为反应物,在脉冲微反装置上,考察了镍改性HZSM-5分子筛的裂解性能和芳构化性能。发现其BTX(苯+甲苯+二甲苯)和低碳烯烃选择性与分子筛的镍浸渍量有关。在分子筛含镍量约为0.2m%时,其选择性为最佳。又进一步研究了水热处理对镍改性分子筛结构、酸性及反应性能的影响。通过实验,提出了用镍改性分子筛来提高烃类的芳构化性能和裂解性能。最后,初步研究了正己烷在镍改性分子筛上的反应机理,并探讨了金属离子镍在反应过程中所起的作用。

The cracking and aromatization performances of Ni-HZSM-5 zeolites have been inves- tigated by means of n-hexane pulse microreactor.The selectivity to aromatics and light olefins in the products varies with the Ni content in the zeolites.Best results are obtained with a Ni content about 0.2m%.The results of n-hexane cracking and aromatization are correlated with the acidic properties of modified zeolites.The effects of hydrothermal treat- ment on the properties and reaction performance are discussed.The experimental results indicate that Ni-HZSM-5 zeolites can improve the cracking and aromatization performance of hydrocarbons.A reaction mechanism for n-hexane over Ni-HZSM-5 are suggested with the role of Ni ions during the reaction being discussed.