Disordered HMWW Zeolite Nanosheets Catalyzing Fructose to 5-Hydroxymethylfurfural.

5-Hydroxymethylfurfural (HMF) is a high value-added platform compound, converted into bio-based polyesters and biofuels etc. In this paper, we used two commercially available hexamethylenimine and cetyltrimethylammonium bromide (CTAB) as the structure-directing agents to synthesize HMWW zeolite nanosheets via one step. A series of HMWW zeolite nanosheets with different disorder index (DI) were controllably prepared by adjusting the amount of CTAB, operating also as an in situ exfoliating agent, converting fructose into HMF in the tetrahydrofuran/NaCl-H2O biphasic solvent with low boiling point. Successful construction of disordered HMWW zeolite nanosheets was verified by PXRD. Further characterizations by BET, SEM and TEM etc. show that HMWW4.0 with the optimum DI of 0.67 has a disordered network-like arrangement of layers with the external surface area of 224 m2/g and the mesoporous size of 3.5 nm. Catalytic evaluations showed that HMF selectivity was closely related to DI of the catalysts. Under the optimized DI, fructose molecules are readily accessible to acidic sites on the external surface while larger external surface area is exposed. The HMWW4.0 zeolite catalyzed fructose dehydration in the biphasic solvent, producing 90% HMF selectivity with 93% fructose conversion at 140 °C for 6 h. In the reuses of the HMWW4.0 catalyst, HMF selectivity was around 90% with fructose conversion decreasing by ca. 10% after six runs, indicating that it possesses the promising stability. [ABSTRACT FROM AUTHOR]