Sulfonic Acid-Functionalized Molecular Sieve as a Solid Acid Catalyst for Transformation of Agricultural Residues to Furfural

Catalytic transformation of agricultural residues to furfural is a potential source of income for those who have biomass residues to be disposed because furfural derivatives are platform molecules for the preparation of various chemicals, additives, and pharmaceutical precursors. In this work, a modified KIT-6 molecular sieve catalyst with dual acid sites of Lewis acid and Brønsted acid is prepared by grafting sulfonic acid groups on Sn4+-doped KIT-6. Characterizations are applied to reveal the generation of Lewis acid and Brønsted acid by the doped Sn4+ and grafted sulfonic acid groups. The dual acid on the catalyst synergistically contributes to the satisfying catalytic transformation of xylose to furfural. In addition, the one-step and two-step transformations of agricultural residues to furfural and 5-hydroxymethylfurfural were studied. The prepared catalyst shows satisfying stability, and the reason for the slight decline of the catalytic performance was revealed.