One-pot hydrolytic hydrogenation of carbohydrates to hexitols catalyzed by Ru loaded P and Si-containing hierarchical porous biochars with excellent catalytic efficiency

Abstract

The one-pot hydrolytic hydrogenation of carbohydrates to sugar alcohols is one of the important value-added transformations of biomass, but the hydrolysis efficiency of carbohydrates in this one-pot conversion is still limited by the high cleavage energy of their β-1,4-glycosidic bonds and the concomitant serious side-reactions. Therefore, it is necessary to develop the new acidic carriers to improve the key first-step hydrolysis. This paper discloses that a forestry processing waste bamboo powder can be converted into the P and Si-containing porous biochar (PSBC) via inserting silica sol, impregnating concentrated phosphoric acid (H3PO4) and heating carbonization. Due to the improved porosity and strong acidity of PSBC and its affinity to β-1,4-glycosidic bonds, this new acid carrier exhibits an outstanding catalysis performance for the hydrolysis of cellulose, cellobiose, especially sucrose and inulin, affording ca. 76.2% glucose yield in cellulose hydrolysis at 150 °C. More importantly, PSBC can efficiently and uniformly load Ru nanometer particles (average size of 1.5 nm) to fabricate 1%Ru/PSBC as an excellent bifunctional catalyst for the one-pot conversion of these carbohydrates to hexitols, affording ca. 85.2% hexitols with 51.7 h−1 turnover frequency in the one-pot conversion of cellulose under 150 °C and 3 MPa H2 pressure. This work not only provides an effective strategy for the preparation of biomass-derived bifunctional catalysts, but also it opens up new voyages for the development of efficient bio-refining.Graphical abstractRu-loaded P and Si-containing porous biochar (1% Ru/PSBC) is an excellent bifunctional catalyst for the hydrolytic hydrogenation of carbohydrates under relatively mild conditions, affording ca. 85.2% hexitols with 51.7 h−1 TOF in the one-pot conversion of cellulose.