Effect of dealumination of HZSM-5 by acid treatment on catalytic properties in non-hydrocracking of diesel

A series of modified HZSM-5 zeolites with different types of acid and different HCl concentrations treatments were synthesized, respectively. The crystal morphology, textural property and acidic property of the catalysts were characterized by XRD, N-2 adsorption-desorption, NH3-TPD, Py-IR and Al-27 MAS NMR spectroscopy. The influences of acid treated types and acid solution concentrations in the pore structure, acidity and non-hydrocracking activity were investigated. The results showed that mesopores were successfully induced to HZSM-5 zeolites after dealumination by HCl and H3PO4 treatment and the acid sites were redistributed. The acidic analysis revealed that the increase of LAS/BAS value was conducive to improving the non-hydrocracking cracking activity and gasoline yield of the samples. It was also observed that an appropriate amount of HC1 treatment can not only play the role of dredge the channel of the zeolites, also introduce some new mesoporous. The hydrochloric acid treated sample (HZ-1.0HA) showed the best diesel non-hydrocracking cracking activity and gasoline yield.