Transformation of Glucose into Sorbitol on Raney Nickel Catalysts in the Absence of Molecular Hydrogen: Sugar Disproportionation vs Catalytic Hydrogen Transfer

Chemocatalytic value addition of glucose without carbon-carbon bond cleavage/formation reactions: an overview

As the monomeric unit of the abundant biopolymer cellulose, glucose is considered a sustainable feedstock for producing carbon-based transportation fuels, chemicals, and polymers. The chemocatalytic value addition of glucose can be broadly classified into those involving C-C bond cleavage/formation reactions and those without. The C6 products obtained from glucose are particularly satisfying because their syntheses enjoy a 100% carbon economy. Although multiple derivatives of glucose retaining all six carbon atoms in their moiety are well-documented, they are somewhat dispersed in the literature and never delineated coherently from the perspective of their carbon skeleton. The glucose-derived chemical intermediates discussed in this review include polyols like sorbitol and sorbitan, diols like isosorbide, furanic compounds like 5-(hydroxymethyl)furfural, and carboxylic acids like gluconic acid. Recent advances in producing the intermediates mentioned above from glucose following chemocatalytic routes have been elaborated, and their derivative chemistry highlighted. This review aims to comprehensively understand the prospects and challenges associated with the catalytic synthesis of C6 molecules from glucose.

Nano Ag/AgBr/g-C3N4 catalyzed the production of hydrogen and reduction of d-glucose to sorbitol under visible light irradiation

In this study, the polymeric graphitic carbon nitride (g-C3N4) was modified by anchoring Ag/AgBr to improve its charge separation efficiency.

Efficient Sorbitol Producing Process through Glucose Hydrogenation Catalyzed by Ru Supported Amino Poly (Styrene-co-Maleic) Polymer (ASMA) Encapsulated on γ-Al2O3

In this work, a core-shell-like sphere ruthenium catalyst, named as 5%Ru/γ-Al2O3@ASMA, has been successfully synthesized through impregnating the ruthenium nanoparticles (NPs) on the surface of the amino poly (styrene-co-maleic) polymer (ASMA) encapsulating γ-Al2O3 pellet support. The interaction between the Ru cations and the electro-donating polymer shell rich in hydroxyl and amino groups through the coordination bond would guarantee that the Ru NPs can be highly dispersed and firmly embedded on the surface of the support. In addition, the solid sphere γ-Al2O3 pellet could serve as the core to support the resulted catalysts applied in the flow process in a trickle bed reactor to promote the productivity. The resulted catalyst 5%Ru/γ-Al2O3@ASMA can be applied efficiently in the glucose hydrogenation and presents a steadfast sorbitol yield of almost 90% both in batch reactor and the trickle bed reactor, indicating the potential feasibility of the core-shell-like catalyst in the efficient production of sorbitol.

Production of Sorbitol via Catalytic Transfer Hydrogenation of Glucose

Sorbitol production from glucose was studied through catalytic transfer hydrogenation (CTH) over Raney nickel catalysts in alcohol media, used as solvents and hydrogen donors. It was found that alcohol sugars, sorbitol and mannitol, can be derived from two hydrogen transfer pathways, one produced involving the sacrificing alcohol as a hydrogen donor, and a second one involving glucose disproportionation. Comparison between short-chain alcohols evidenced that ethanol was able to reduce glucose in the presence of Raney nickel under neutral conditions. Side reactions include fructose and mannose production via glucose isomerization, which occur even in the absence of the catalyst. Blank reaction tests allowed evaluating the extension of the isomerization pathway. The influence of several operation parameters, like the temperature or the catalyst loading, as well as the use of metal promoters (Mo and Fe-Cr) over Raney nickel, was examined. This strategy opens new possibilities for the sustainable production of sugar alcohols.