含氧化铝Zn/HZSM-5催化剂芳构化反应性能的研究

考察了在含氧化铝载体条件下,不同Zn负载量改性后HZSM-5催化剂的MTA反应性能。采用BET、XRD、PyFTIR、NH3-TPD和H2-TPR等分析手段对催化剂进行表征。实验结果表明,氧化铝载体的加入使得HZSM-5催化剂产生了介孔并且增强了Zn物种在催化剂表面的稳定性;Zn物种的加入破坏了HZSM-5分子筛的骨架结构、改变了催化剂表面酸性;此外,Zn物种的加入可以促进MTA过程脱氢反应的进行,中间产物烯烃的后续芳构化过程受到抑制;在实验的考察范围内,当Zn负载量为0.5%(质量分数)时,芳烃(C6~11)收率存在最大值21.0%(质量分数);甲醇的芳构化能力会受到生焦的抑制,然而,再生后的催化剂呈现更高的芳烃收率。

Study on the reaction per formance of methanol to aromatics over Zn/HZSM-5 catalysts with alumina

The present paper investigated the effect of Zn modified HZSM-5 catalysts on the reaction performance of methanol to aromatics with the presence of alumina. The catalysts were characterized by BET, XRD, Py-FTIR, NH₃-TPD, and H₂-TPR techniques, respectively. The experimental result demonstrated that the introduction of alumina produced mesopores in the HZSM-5 catalyst and strengthened the stability of Zn species on the surface of the catalyst. The introduction of Zn species broke the structure of HZSM-5 zeolite and changed the surface acidity of the catalyst. In addition, Zn species might contribute to the dehydrogenation reaction of MTA. Meanwhile, the subsequent aromatization process of olefins was impressed. Within the scope of this study, the maximum value of aromatic yield (C_6~11) reached 21.0% when the loading of Zn was 0.5%. The aromatization of methanol is at the control of coke on the catalyst. However, the regenerated catalyst exhibited a higher aromatic yield.