Effect of synthesis conditions on zeolite Beta properties and its performance in vacuum gas oil hydrocracking activity

摘要

The influence of synthesis conditions such as crystallization time, temperature and gel composition on crystallization of zeolite Beta was studied. Optimal temperature for the synthesis was 170 degrees C. A crystallization time from 24 to 36 h and 25 and 70 SiO2/Al2O3 ratio in the synthesis gel were used. In this way, three pure zeolite Beta samples were obtained under hydrothermal conditions. Change of these conditions led to zeolites with different Si/Al ratio, with one composition with low SiO2/Al2O3 ratio (20 < Si/Al < 15) in the final product. The materials were characterized by X ray diffraction, elemental analysis, thermal analysis, N-2 physisorption, Al-27 solid-state NMR, ammonia temperature programmed desorption, and infrared spectroscopy of adsorbed pyridine. Al-27 MAS-NMR measurements showed no significant differences in the proportion of tetrahedral and octahedral aluminum. Hydrocracking catalysts were prepared from the calcined zeolites. The evaluation of these catalysts in vacuum gasoil hydro cracking showed that textural properties such as mesopore volume and effects of solvatiori in zeolite voids have an impact on selectivity towards gasoline and middle distillates. (C) 2016 Elsevier Inc. All rights reserved.