Use of electrocatalytic membrane reactor for synthesis of sorbitol

Electrocatalytic Hydrogenation and Deoxygenation of Glucose on Solid Metal Electrodes

“…(2)] due to the generation of OH À , which led to a deviation of the interfacial pH from the pH of the bulk solution (0.1 m Na 2 SO 4 ). In addition, the absence of mannitol, an isomer of sorbitol, in the product spectra supports the model of deoxygenation from glucose since the chiral carbon (the ketone C in fructose) is hydrogenated into two isomeric alcohols with a similar ratio (sorbitol 40 % and mannitol 60 %), as demonstrated by Owobi-Andely et al [9] We also emphasize that the formation of 2-de-oxysorbitol, was an electrocatalytic reaction that occurred only on sp metals, for reasons that remain to be understood. The effect of the high pH near the electrode surface was that the cyclic (inactive) form of glucose easily underwent mutarotation to the linear (electroactive) form, which is considered as a rate-determining step.…”

“…These aspects were also emphasized recently for the electrochemical oxidation of hydroxymethylfurfural. [9,20] Unsurprisingly, we observed a trace of fructose at high cathodic current in all experiments, even though the collected samples ranging in pH from 7 to 10 were immediately neutralized by adding 10 mm phosphate buffer solution. (1)] and especially during hydrogen evolution [Eq.…”

“…[1,2] Glucose, as the monomer of cellulose, plays a central role in biomass conversion. [4][5][6]9] Controlling the pH and temperature during the hydrogenation process is important for obtaining a high yield of sorbitol because strongly acidic conditions lead to H 2 formation only, also, alkaline conditions and high temperatures cause mutarotation of glucose resulting in the formation of by-products. Sorbitol is a promising platform polyol used as an additive in foods, drugs, cosmetics, and various chemicals including vitamin C. [3] Using electrochemical approaches, sorbitol has been produced from aqueous glucose solution by applying a certain current or potential on large-surface-area catalysts such as Raney-Ni, [4,5] or poor metals at moderate pH (3)(4)(5)(6)(7)(8)(9)(10)(11) [4,[6][7][8] and temperature (<60 8C), [4][5][6][7][8] in a flow reactor.…”

“…In particular, hydrogenation of glucose to sorbitol is a very important reaction from synthetic and hydrogen-storage points of view. Sorbitol is a promising platform polyol used as an additive in foods, drugs, cosmetics, and various chemicals including vitamin C. [3] Using electrochemical approaches, sorbitol has been produced from aqueous glucose solution by applying a certain current or potential on large-surface-area catalysts such as Raney-Ni, [4,5] or poor metals at moderate pH (3)(4)(5)(6)(7)(8)(9)(10)(11) [4,[6][7][8] and temperature (<60 8C), [4][5][6][7][8] in a flow reactor. [4][5][6]9] Controlling the pH and temperature during the hydrogenation process is important for obtaining a high yield of sorbitol because strongly acidic conditions lead to H 2 formation only, also, alkaline conditions and high temperatures cause mutarotation of glucose resulting in the formation of by-products.…”

“…Although electrocatalytic glucose hydrogenation to sorbitol has been applied on an industrial scale, [10] a fundamental understanding of the reactions linking catalysts and voltammetry has not been reported, mainly due to existing technical limitations regarding the online analysis of products. For instance, conventional bulk electrolysis requires a long operating time to find the optimum potential or current to produce a high yield of sorbitol, [6][7][8][9] moreover, such studies give little insight into the mechanistic aspects of the reaction. This lack of insight hampers the application of electrochemical methods in the conversion of sugar compounds, and a detailed study, such as reported herein, is warranted.…”