Three-dimensional spherical ordered mesoporous Al-MCM-48 solid acid catalysts for the rapid conversion of biomass-derived GVL to butene

The catalytic production of butene from biomass-derived γ-valerolactone (GVL) plays a crucial role in advancing sustainable energy development. In this paper, MCM-48 featuring a large surface area and ordered three-dimensional mesoporous structure, was prepared using a hydrothermal method with CTAB as the template agent. The final solid acid x wt%Al-MCM-48 catalysts were then synthesized via a simple impregnation method, using AlCl 3 as the aluminum source and ethanol as the solvent. It was found that aluminum species exist on the surface of MCM-48 in tetra-, quintu-, and hexa -coordinated forms, which leads to the formation of a substantial number of weak Brønsted and Lewis acid sites. Although the introduction of Al species further reduces the specific surface area of the catalyst, the optimal 9wt%Al-MCM-48 catalyst still maintains a high value of 651 m 2 ·g −1 , with the largest number of weak acid sites, amounting to 0.60 mmol·g −1 . The ordered three-dimensional mesoporous structure, large number of surface weak acid sites, and suitable ratio of Brønsted to Lewis acid endow the 9wt%Al-MCM-48 catalyst with high catalytic activity for the conversion GVL to butene. Upon optimization of the reaction parameters, the 9wt%Al-MCM-48 catalyst achieves a butene yield of over 90% within a 90 min reaction period at 300 °C. Further evaluation of the catalyst’s cycling stability revealed that it maintains 74% of butene yield following five consecutive cycles.