Exceptionally Efficient and Recyclable Heterogeneous Metal–Organic Framework Catalyst for Glucose Isomerization in Water

Abstract

Heterogeneous catalysts are desired for the conversion of glucose, the most abundant sugar in renewable biomass, but presently their synthesis requires highly toxic chemicals with long synthesis times. We report the conversion of glucose into fructose and 5‐hydroxymethylfurfural on a heterogeneous catalyst that is stable and selective and operates in the most environmentally benign solvent, water. We used a bifunctional solid with Lewis and Brønsted acid sites by partially replacing the organic linker of the zirconium organic framework UiO‐66 with 2‐monosulfo‐benzene‐1,4‐dicarboxylate. This catalyst showed high product selectivity (90 %) to 5‐hydroxymethylfurfural and fructose at 140 °C in water after a reaction time of 3 h. It was recyclable and showed only a minor loss in activity after the third recycle, offering a realistic solution for the bottleneck glucose isomerization reaction for scale‐up and industrial application of biomass utilization.

Glucose Isomerization and Epimerization over Metal‐Organic Frameworks with Single‐Site Active Centers

“…On the other hand, the relative content of C, H, N and metal (Cr and Zr), as well as weight of MOFs before and after the reaction are almost unchanged (Table S1). In addition, only trace amounts of metal are present in the reaction solution (Table S2), which is an indicative of negligible metal leaching, as reported previously by Degirmenci . As indicated from the N 2 adsorption/desorption isotherms of MOFs after exposure to the reaction mixture (Figure S2), the amount of N 2 adsorbed along with textural properties (Table S1) decrease for Cr‐MIL‐101 and NH 2 ‐Zr‐UiO‐66, whereas are negligible for Zr‐UiO‐66.…”

Selective Glucose‐to‐Fructose Isomerization over Modified Zirconium UiO‐66 in Alcohol Media

“… Glucose isomerization profiles for UiO‐66‐Fm in (a) MeOH, (b) EtOH, (c) 1‐PrOH (open symbols refer to UiO‐66‐Id), and (d) performance comparison of UiO‐66‐Fm in 1‐PrOH (black), Sn‐SPP in EtOH (red), Sn‐SPP in 1‐PrOH (red circle, open), NU‐1000 in EtOH (blue), and UiO‐66‐SO 3 H in water (black square, open). Reaction conditions: 0.007 g of catalyst, 5 mL of solvent, 0.04 g of d ‐glucose, 90 °C, 600 rpm.…”

“…A maximum of 56 % fructose yield at 82 % glucose conversion was achieved for the reaction in 1‐propanol. UiO‐66‐Fm shows a fructose selectivity and yield comparable to the one previously reported for Sn‐SPP in ethanol (and 1‐propanol, in this work), higher than that obtained for another zirconium MOF, NU‐1000, and similar to the recently reported for UiO‐66‐SO 3 H in water (Figure d).…”

“…The Zr clusters can act as Lewis acid sites, as it was observed for the cyclization of benzaldehyde and aldol condensation . A modified UiO‐66 with Brønsted acid sites has been studied for glucose isomerization to fructose in water, achieving high selectivity at 48 % glucose conversion . A similar synthesis procedure was used to make an active catalyst for fructose dehydration to HMF, showing high activity and stability at reaction conditions …”

A Chromium Hydroxide/MIL‐101(Cr) MOF Composite Catalyst and Its Use for the Selective Isomerization of Glucose to Fructose

“…MOF catalysts have been explored for glucose isomerization in water and recently their performance has approached that of the best zeolite catalysts (Sn-Beta). [31][32][33] Although aM OF-derived catalyst has been explored for glucose isomerization in alcohol, its performance was below that obtained by zeolite catalysts,s uch as Sn-SPP. [34] Herein, we demonstrate that achromium hydroxide/MIL-101 catalyst can isomerize glucose to fructose at glucose conversion and fructose yield comparable to those obtained by optimized zeolite catalysts.W ea lso show that the isomerization mechanism is predominantly by proton-transfer as in basecatalyzed isomerization, possibly due to chromium hydroxide, while the ketalization reaction is catalyzed by MIL-101.…”