Highly Efficient 5‑Hydroxymethylfurfural Production from Glucose over Bifunctional SnO x /C catalyst

Catalytic conversion of glucose to 5-hydroxymethylfurfural (HMF) is a highly desirable routine for producing value-added chemicals. Herein, by using glucose as carbon source to fabricate porous carbon support, SnCl4 and citric acid were selected for forming Lewis acidic/basic SnO x and Brønsted −COOH over support, respectively, bifunctional solid acid tin oxide/carbon catalysts were prepared by a hydrothermal-pyrolysis strategy. It is found that the acid density of SnO x /C could be tuned by adjusting SnCl4 dosage and pyrolysis temperature. In a H2O-NaCl/THF biphasic system, 92.1% glucose conversion and 84.1% HMF yield were achieved over an optimized 3.0-SnO x /C-500 catalyst at 180 °C for 2 h. This catalyst demonstrates excellent recyclability in this reaction for five times and is also versatile for one-pot transformation of cellulose to HMF with 39.9% yield. The superior performance of 3.0-SnO x /C-500 could be ascribed to its highly dispersed SnO x nanoparticles, a suitable ratio of Brønsted to Lewis acids, as well as accessible pore-structure of the catalyst.