Key Words:Zeolites; Phase-transfer catalysis; Catalytic hydrocracking; Template removal
Abstract:Templated hydrothermal is one of the most used modern methods for zeolites synthesis. Traditional template removal method, i.e. high temperature (> 723 K) combustion, usually results into zeolites structure damage as well as associates massive energy consumption. Herein, we report a catalytic hydrocracking (CHC) approach to remove templates at mild temperature (613 K). The methodology is shown in the synthesis of two model zeolites, beta (β) and titanium silicalite-1 (TS-1) zeolite. Active spillover hydrogen generating from the employed heterogeneous Pd/SiO2 catalyst is believed to be the critical species. Interphase spillover facilitates active atomic hydrogen transport, leading to templates cracking into small molecules and removal. The approach shows high efficiency on template removal while mild condition avoids structure damage and maintains local structure. The activated β-zeolite using this CHC approach demonstrate promoted catalytic performance in esterification reaction between ethanol and acetate acid with acetate acid conversion of 43%, even higher than that with conventional calcination (Cal) method (40%). It also exhibits potential application in methanol to olefin (MTO). In addition, CHC- and Cal- TS-1 zeolite demonstrate very similar performance in ammoximation. The approach can be applicable to other template-assisted porous materials, which indicates its great potentials in the future
Volume:
Issue:346
Translation or Not:no