Ultrasonic-assisted synthesis of acidic Al-MCM-41 for enhanced selective production of HMF from glucose

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 displayed 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 materials, such as Sn-MCM-41. (1) Ultrasonic irradiation facilitated rapid Al-MCM-41 synthesis at room temperature (2) The as-prepared Al-MCM-41 exhibited super activity in glucose-to-HMF conversions (3) Strong acidity and BAS-LAS synergy enhanced the catalytic activity of Al-MCM-41-10 (4) Ultrasonic-assisted method can be extended to the synthesis of Sn-MCM-41 materials