Zn助剂对WC/HZSM-5催化正己烷芳构化性能影响

Effect of zinc additive on n-hexane aromatization over WC/HZSM-5 catalysts

以WC/HZSM-5为前驱体制备了一系列不同Zn含量的Zn-WC/HZSM-5催化剂,采用X射线衍射、扫描电子显微镜、N2物理吸附、傅里叶变换红外光谱和热重分析等手段对Zn-WC/HZSM-5的晶相、形貌、比表面积、酸性质、积炭量等进行了表征,并研究了正己烷芳构化的催化性能,探究了助剂Zn与WC在反应过程中的作用。结果表明,Zn的引入可以提高催化剂的芳烃选择性和芳烃收率。当Zn负载量为1.5%(质量分数)时,所制备的Zn-WC/HZSM-5催化剂芳构化活性最佳,芳烃收率达到36.18%。Zn的引入不仅改变了WC/HZSM-5表面的酸性分布,而且可以减少WC/HZSM-5催化剂的积炭量。

A series of Zn-WC/HZSM-5 catalysts with different amounts of Zn additive were prepared based on the precursor WC/HZSM-5. The samples were characterized with X-ray diffraction, scanning electron microscopy, N2adsorption-desorption, Fourier transform infrared spectroscopy and thermogravimetric analyzer. Aromatization of n-hexane was evaluated over the Zn-WC/HZSM-5 catalysts in a fixed-bed micro reactor. The role of metal components and the reaction mechanism were studied. Both aromatic selectivity and yield increased with Zn-WC/HZSM-5. Yield increased to 36.18% when the Zn-WC/HZSM-5 displayed the best activity with the concentration of Zn 1.5%（mass）. Introduction of Zn into WC/HZSM-5 led to redistribution of acid sites on the surface of catalyst and also caused decrease of coke deposition.