Natural mineral bentonite as catalyst for efficient isomerization of biomass-derived glucose to fructose in water

The development of inexpensive and efficient heterogeneous catalyst for the conversion of biomass including food and winery processing waste to value-added products is crucial in biorefinery. Glucose could be obtained via the hydrolysis of waste cellulose or starch-rich material, and the isomerization of glucose to fructose using either Lewis acid or Bronsted base catalysts is an important route in biorefinery. As a natural clay mineral, bentonite (Bt) is widely used as adsorption material and catalyst support, but how its intrinsic acid-base properties can impact the biomass conversion chemistry is still rarely reported. In this study, we investigated the influence of the textural and acid-base properties of Bt on the glucose isomerization reaction. The reaction kinetics and mechanism, and the effect of Al3+-exchange were explored. The results showed that the activation energy of Bt-catalyzed glucose conversion was 59.0 kJ mol(-1), and the in-situ Fourier transform infrared spectrometer (FT-IR) characterization proved that Bronsted base was responsible for the isomerization. The highest fructose yield of 39.2% with 86.3% selectivity could be obtained at 110 degrees C for 60 min in water. Alkaline rinse and calcination can recover most of the catalytic activity of the spent catalyst. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

This study investigated the influence of the textural and acid-base properties of bentonite on glucose isomerization reaction, showing that Bromsted base was responsible for the isomerization. The highest fructose yield of 39.2% with 86.3% selectivity was achieved, and alkaline rinse and calcination were able to recover most of the spent catalyst's catalytic activity.