Abstract
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•Alanine successfully functionalized onto MCM-41 framework.•MCM-41-16Alanine had a medium (0.087 mmol g−1) and strong (0.587 mmol g−1) basic strengths.•Selective synthesis of dioxolane biofuel additive via MCM-41-16Alanine.•MCM-41-16Alanine showed excellent stability and reusability in acetalization of glycerol.
Highly active and selective acetalization catalyst, viz. alanine functionalized MCM-41 (MCM-41-16Alanine), synthesized using post-grafting method is reported. The mesoporous solid is first reacted with (3-chloropropyl)triethoxysilane (CPTES) before alanine is covalently bonded onto the hybrid support as confirmed by TGA/DTG, IR and UV-Raman spectroscopy analyses. Furthermore, the meso-ordered structure of MCM-41 is also retained after surface modification as revealed by the X-ray powder diffraction (XRD) and transmission electron microscopy (TEM) studies. The resulting bifunctional catalyst bearing both acidity and basicity exhibits good catalytic performance in the acetalization of glycerol with furfural reaction where 90% conversion with 78% selective to (2-(furan-2-yl)-1,3-dioxolan-4-yl)methanol-a valuable dioxolane biofuel additive-are achieved under optimized reaction conditions. Furthermore, the excellent catalytic performance of MCM-41-16Alanine is demonstrated when it is compared to other reported catalysts thanks to its large surface area, acid-base bifunctionality and mesopore confinement that induce synergistic effects. The catalyst also displays high catalyst reusability and no significant deterioration in catalytic activity is shown after six consecutive runs, thus offering a green pathway for synthesizing dioxolane biofuel additive with high selectivity.