Efficient Conversion of Glucose to 5-Hydroxymethylfurfural Catalyzed by Phosphate-Modified SnO₂ Derived from Calcined Sn-MOFs

5-Hydroxymethylfurfural (5-HMF), a crucial biomass-based platform chemical, has significant potential for producing fuels, polymers, and other valuable products, thus advancing sustainable development. However, achieving efficient production remains challenging due to the absence of highly effective catalysts. To address this, SnO2 modified with phosphate was synthesized by calcining Sn-MOFs after the initial impregnation with ammonium dihydrogen phosphate (NH4H2PO4). The resulting material was characterized using various techniques to evaluate its crystal structure, morphology, and chemical composition and was then used to catalyze the conversion of glucose to 5-HMF in a methyl isobutyl ketone/H2O system. The modification did not alter the crystal structure of SnO2 but reduced its crystallinity, resulting in a coarser surface and increased surface area compared to that of pure SnO2. Moreover, reduced agglomeration was achieved through the template effect of MOFs. Phosphate was well-dispersed within the SnO2 framework, leading to a significant enhancement in both Brønsted and Lewis acidities. The introduction of phosphate improved the yield of 5-HMF from 13.6 to 43.2% compared to that of pure SnO2, with the highest yield of 49.8% achieved under optimized conditions. Additionally, the catalyst demonstrated excellent reusability, maintaining its catalytic performance after three cycles. This work presents a method for preparing phosphate-modified SnO2 catalysts with high dispersion, efficient catalytic performance, and reusability to produce 5-HMF through calcination of the corresponding MOFs.