Preparation of isosorbide by dehydration of sorbitol on hierarchical Beta zeolites under solvent-free conditions

A series of hierarchical Beta zeolites (Q-beta) were synthesized using the silanization template method. The characterization results suggested that the pore structure and acidity of the catalysts were influenced by varying the Si/Al molar ratio in the precursor. For the reaction of dehydration of sorbitol to isosorbide, the Q-beta-46(8) catalyst exhibited significantly improved catalytic performance with a yield of up to 83 % after 12 h of reaction at moderate temperature (170 degree celsius), higher than any other zeolite catalysts. The catalyst maintained good catalytic performance after five cycles. The unique activity might be attributed to its excellent secondary porosity (77.66 %), higher Bronsted acidic site concentration (63.18 mu mol/g) and BAC/LAC ratio (0.172).