Haoran Li,Qisong Yi,Yuanchao Shao,Haimei Xu,Zichun Wang,Yuanshuai Liu
The sustainable transformation of renewable biomass into value-added chemicals is essential to addressing global environmental and energy challenges. Among these, the production of 5-hydroxymethylfurfural (HMF) from biomass-derived glucose is of considerable interest for both scientific and industrial applications. In this study, mesoporous aluminium incorporated MCM-41 catalysts (Al-MCM-41) were synthesized using an ultrasonic-assisted method at room temperature. Their ordered mesoporous structure was preserved even with high concentrations of Al. The catalysts' acidity was finely tuned by varying the Si/Al ratio, enabling the development of an optimal catalyst to enhance the glucose-to-HMF conversion via Brønsted and Lewis acid catalysis. Characterization techniques, including XRD, TEM, N 2 adsorption-desorption, NH 3 -TPD, Py-FTIR, 29 Si and 27 Al MAS NMR, were employed to evaluate the catalysts’ structure and acidity. The results revealed that ultrasonic-assisted synthesis strategy improves Al dispersion, optimizes acid site density, and significantly enhances HMF yield and selectivity. The best-performing Al-MCM-41-10 catalyst can afford ∼90 % glucose conversion with ∼60 % HMF selectivity at 160 °C, and displays excellent reusability under the applied reaction conditions. This study provides valuable insights into designing efficient catalysts for biomass conversion and underscores the broad applicability of the ultrasonic-assisted synthesis method for other heteroatom-doped mesoporous materials, such as Sn-MCM-41.
Hao Runming,Du An,Zhu Qingling,Wu Xue,Liu Sijia,Wang Ke,Wang Yang
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-H 2 O 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 HMWW 4.0 with the optimum DI of 0.67 has a disordered network-like arrangement of layers with the external surface area of 224 m 2 /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 HMWW 4.0 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 HMWW 4.0 catalyst, HMF selectivity was around 90% with fructose conversion decreasing by ca. 10% after six runs, indicating that it possesses the promising stability. Graphical Abstract
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