Ionic Liquid-Encapsulated Zeolite Catalysts for the Conversion of Glucose to 5-Hydroxymethylfurfural

Ionic Liquid (1-Butyl-3-methylimidazolium Bromide ([BMIM]Br) or Choline Chloride (ChCl)) encapsulated zeolites (HY and H-MOR) have been synthesized by ship-in-a-bottle strategy and tested for selective conversion of glucose to 5-Hydroxymethylfurfural (HMF). Nitrogen sorption analysis showed that the surface area and total pore volume decreased and average pore size increased significantly when the zeolites are encapsulated with ionic liquids. The major effect was found to be on the microporosity whereas the mesoporosity is affected only marginally. From Thermogravimetric Analysis it is observed that the decomposition temperature of ionic liquids increased when encapsulated in the zeolite. The catalytic tests were carried out in presence of NaCl and an extraction phase to remove the formed HMF. The test results of BMIMBr-H-MOR indicate that even though there is a significant decrease in the surface area with encapsulation, the yield and selectivity are higher with this catalyst as compared to its bare zeolite counterpart. The effect of the addition of NaCl and extraction phase and reaction conditions such as reaction time and temperature on activity and yield of HMF are evaluated on the best catalyst. In catalyst stability study, the reasons for deactivation of catalyst are identified by post-reaction catalyst characterizations.