Influence of Zn species in HZSM-5 on ethylene aromatization

Zn-containing HZSM-5 zeolites with different Zn contents were prepared by ion exchange and physically mixing methods, and were characterized by X-ray diffraction, scanning electron microscope, N2 adsorption-desorption, NH3 temperature programmed desorption, pyridine adsorption infrared spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy and X-ray photoelectron spectroscopy. Zn species introduced into HZSM-5 were identified as ZnO crystals, ZnO clusters in the zeolite channel and Zn(OH)+ species formed from a solid state reaction between dispersed ZnO and the protons in the zeolite. The preparation method has a significant influence on the distribution of the Zn species. The catalytic behavior of Zn-containing HZSM-5 with different Zn contents showed that the Zn(OH)+ and ZnO species were responsible for aromatic formation from ethylene.

Graphical AbstractAn efficient Zn-containing HZSM-5 catalyst for ethylene aromatization was prepared by physically mixing. Both Zn(OH)+ and ZnO species facilitated the dehydrogenation of light alkanes, and promoted the formation of aromatics.Figure optionsDownload as PowerPoint slide