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• A mixed-linker method is used for creating defects in MIL-53(Al)-NH 2. • The presence of defects can finely tailor the acidity of catalyst. • A high glucose conversion of 98.3 % with a 5-HMF yield of 59.3 % is obtained. • The defective catalyst presents excellent recyclability and reusability. • The synergy of Lewis and Brønsted acid contributes to the superb performance. Developing functional catalysts with both Lewis and Brønsted acid sites is an essential task for achieving the direct conversion of glucose to 5-hydroxymethylfurfural (5-HMF), a process that is crucial for the sustainable production of renewable fuels and chemicals. In this work, a mixed-linker strategy is proposed to prepare defective MIL-53(Al)-NH 2 by introducing trifluoroacetic acid into the MIL-53(Al)-NH 2 synthesis process. The creation of defects facilitates the exposure and accessibility of Al3+ centers, as well as changes the coordination environment within the MIL-53(Al)-NH 2 skeleton. Both the number of Lewis and Brønsted acid sites are boosted, which is beneficial for glucose activation and 5-HMF generation. Through optimizing the reaction conditions, a glucose conversion of 98.3 % with a 5-HMF yield of 59.3 % was achieved by using defective 6d-MIL-53(Al)-NH 2 in a biphasic tetrahydrofuran/H 2 O NaCl system. Moreover, the 6d-MIL-53(Al)-NH 2 catalyst showed excellent recyclability and reusability, with its catalytic efficiency maintained almost unchanged for consecutive 10 cycles. The catalytic mechanism was elucidated and the acidity of the Lewis and Brønsted acid was modulated by defect engineering to achieve exceptional performance. [Display omitted] [ABSTRACT FROM AUTHOR]

Interest in production and utilization of 5-hydroxymethylfurfural (5-HMF) has risen greatly as 5-HMF is considered as an extremely important platform compound. It remains a huge challenge to develop efficient and low-cost solid catalysts with suitable acid properties for sustainable production of 5-HMF from glucose. Herein, a bifunctional Sn-modified SBA-15 (Sn–OH/SBA-15) catalyst containing both Lewis and Brønsted acid sites was fabricated. Dimethyldichlorostannane was grafted onto mesoporous SBA-15, and the methyl groups were then converted to hydroxyl groups by calcination. The synergistic effects of Lewis and Brønsted acid significantly boosted the synthesis of 5-HMF from glucose adopting the one-pot method. By optimizing the reaction conditions, the Sn–OH/SBA-15 sample was able to achieve a glucose conversion of 96.9% with a 5-HMF yield of 70.6% (180 °C, 5 h). Moreover, the catalyst demonstrated superior recyclability and reusability. This work would enlighten the exploitation and preparation of highly efficient catalysts for the transformation of carbohydrates into value-added chemicals. [Display omitted] • Solid catalyst is used for transformation of glucose to 5-HMF. • Mesoporous structure and appropriate acid sites favor the production of 5-HMF. • A high 5-HMF yield of 70.6% is achieved by adding Sn–OH/SBA-15. [ABSTRACT FROM AUTHOR]