The construction of a series of hierarchical MWW-type zeolites and their catalytic performances for bulky aldol condensation

Abstract

The construction of hierarchical pore systems from the post-synthesis modifications of lamellar zeolite catalysts have attracted wide interests to solve the diffusion limitations in the catalytic application of zeolite catalysts. Herein, the interlayer expanded MWW with different interlayer spacing were obtained, based on the post-synthesis modifications of a swollen multilamellar MWW precursor, in which the MWW layers were pillared by cetyltrimethylammonium bromide (CTAB) surfactant with 25 Å interlayer distance. The direct calcination and the post-synthesis modifications led to zeolite catalysts with more open pore structures (hierarchical, interlayer expanded and pillared), which were evidenced by a series of characterizations, such as PXRD, TEM, N2 adsorption-desorption etc. Moreover, the catalytic performances of the hierarchical MWW (H-MWW), interlayered expanded zeolite IEZ-MWW and Pillared-MWW catalysts were compared with 3D-MWW and ZSM-5 in the condensation of cyclohexanone with glycol or benzaldehyde with 1-pentanol. The catalysts prepared in this study show better catalytic activities than 3D-MWW and ZSM-5.