Promoted metal utilization capacity of alkali-treated zeolite: Preparation of Zn/ZSM-5 and its application in 1-hexene aromatization
Promoted metal utilization capacity of ZSM-5 zeolite has been achieved via the intracrystalline mesopores created by alkali treatment. The untreated and alkali-treated Zn/ZSM-5 catalysts were prepared by the conventional liquid ion exchange and impregnation methods. These catalysts were investigated by several techniques: N2 adsorption–desorption, transmission electron microscopy, X-ray photoelectron spectroscopy, ammonia temperature-programmed desorption, and Fourier transform infrared spectroscopy. Compared with the untreated catalysts, the alkali-treated catalysts exhibited higher Zn-loading in liquid ion exchange, better metal distribution and more Lewis acid sites in impregnation, owing to the location of Zn species in the created intracrystalline mesopores. The alkali-treated Zn/ZSM-5 catalysts displayed dramatically improved catalytic stability in 1-hexene aromatization. These findings show new potential for developing some advanced bifunctional metal-zeolite catalysts by a facile and low-cost method.
Graphical abstractThe metal utilization capacity of ZSM-5 zeolite was promoted via the intracrystalline mesopores created by alkali treatment. Parts of the metal species were located in the mesopores and consequently the synergy effect between metal species and Brønsted acid sites was enhanced. The 1-hexene aromatization was used as a model reaction to demonstrate the predominance of the alkali-treated metal-zeolite bifunctional catalysts.Figure optionsDownload full-size imageDownload as PowerPoint slide
Journal: Applied Catalysis A: General - Volume 360, Issue 1, 31 May 2009, Pages 8–16