Characterization and catalytic performance of modified nano-scale ZSM-5 for the acetone-to-olefins reaction
•Acidity modification of ZSM-5 zeolite was examined.•Phenyl silane and tri-phenyl silane were used as new deactivators.•Catalytic properties of ZSM-5 zeolites can be controlled.•Modified ZSM-5 was effective in acetone-to-olefins reaction.
In the acetone to olefins (ATO) reaction using ZSM-5 zeolites, isobutylene is initially produced via decomposition of an acetone dimer, followed by dimerization of the isobutylene and its cracking to form ethylene and propylene. Nano-scale ZSM-5 zeolite exhibited stable activity during the ATO reaction compared with that of macro-scale ZSM-5. In order to further improve the catalytic stability of the nano-scale ZSM-5, control of the acidity of nano-scale ZSM-5 zeolites through SiO2 unit formation was examined using phenyl silane and triphenyl silane as new deactivators. This modification led to an increase in the olefins yield and an improvement in the catalyst lifetime. In particular, the regioselective deactivation of acid sites located on the external surface of the zeolite inhibits the formation of aromatics. Moreover, the acidity control within the pores significantly improved the catalyst lifetime. Notably, the modified nano-scale ZSM-5 zeolite exhibited a stable olefins yield above 55 C-mol% for 180 h.
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Journal: Applied Catalysis A: General - Volume 475, 5 April 2014, Pages 127–133