Dehydration of glycerol to acrolein using H-ZSM5 zeolite modified by alkali treatment with NaOH

DECOLATTI, H.P.; DALLA COSTA, B.O.; QUERINI, C.A.

MICROPOROUS AND MESOPOROUS MATERIALS

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2015 vol. 204 p. 180 - 189

1387-1811

The dehydration of glycerol to acrolein has been studied using H-ZSM5 zeolite treated in alkaline mediumin order to develop mesoporosity by desilication. Treatment of H-ZSM5 zeolite (Si/Al: 15) in NaOH solutionsleads to mesoporosity development due to the preferential extraction of Si from the zeolite framework(desilication) without significant modification of the intrinsic zeolite properties. The samples werestudied by powder X-ray diffraction (XRD), N2 adsorption, pyridine-temperature programmed desorption(Py-TPD) and FTIR of adsorbed pyridine. The coke deposits were analyzed by temperature programmedoxidation (TPO). The alkaline treatment conditions led to an increase in the mesopore surface area from254 m2 g1 for the calcined zeolite to 325 m2 g1 for the alkaline-treated material, while the microporevolume was only slightly decreased (from 0.136 to 0.130 ml g1). Besides substantial mesoporosity development,the zeolite maintained Brønsted acidic properties, which are highly attractive in order to promoteacid-catalyzed reactions like glycerol dehydration. Catalytic testing of the modified solidsshowed an improved performance in dehydration of glycerol to acrolein, due to the unique interplaybetween improved physical transport in the shortened micropores and the preserved high density of acidsites. The catalyst stability was improved upon desilication due to an increase in coke tolerance. A treatmentof both solids in air at 773 K led to a partial regeneration of acid sites for glycerol dehydration.