Electroreforming of Glucose and Xylose in Alkaline Medium at Carbon Supported Alloyed Pd3Au7 Nanocatalysts: Effect of Aldose Concentration and Electrolysis Cell Voltage

Thibault Rafaïdeen,Neha Neha,Christophe Coutanceau,Stève Baranton,Bitty Roméo Serge Kouamé

doi:10.3390/cleantechnol2020013

Abstract

The effects of cell voltage and of concentration of sugars (glucose and xylose) on the performances of their electro-reforming have been evaluated at a Pd3Au7/C anode in 0.10 mol L−1 NaOH solution. The catalyst synthesized by a wet chemistry route is first comprehensively characterized by physicochemical and electrochemical techniques. The supported catalyst consists in alloyed Pd3Au7 nanoparticles of circa 6 nm mean diameter deposited on a Vulcan XC72 carbon support, with a metal loading close to 40 wt%. Six-hour chronoamperometry measurements are performed at 293 K in a 25 cm2 electrolysis cell for the electro-conversion of 0.10 mol L−1 and 0.50 mol L−1 glucose and xylose at cell voltages of +0.4 V, +0.6 V and +0.8 V. Reaction products are analyzed every hour by high performance liquid chromatography. The main products are gluconate and xylonate for glucose and xylose electro-reforming, respectively, but the faradaic yield, the selectivity and the formation rate of gluconate/xylonate decrease with the increase of aldose concentration, whereas lower faradaic yields and higher formation rates of gluconate/xylonate are observed at +0.8 V than at +0.4 V (higher chemical yields).

Highlights

With the perspective of moving from fossil to renewable resources to produce fine chemicals, the conversion of hexoses and pentoses into their corresponding carboxylic acid derivatives has recently received much attention
In a previous paper [24], we have studied the electrocatalytic oxidation of 0.10 mol L−1 glucose (18.0 g L−1) and 0.10 mol L−1 xylose (15.0 g L−1) at palladium/gold nano-alloys of different atomic ratios deposited on a high specific surface area carbon support (PdxAu10-x/C, x from 0 to 10) and we showed that the Pd3Au7 atomic composition allowed reaching both high activity and selectivity towards gluconate and xylonate, respectively, by avoiding the breaking of the C-C bonds at low anode potentials
In a previous work [24], we have shown that the electro-conversion of 0.10 mol L−1 glucose at a cell voltage of +0.4 V produced few amounts of xylonate and threonate

Summary

Introduction

With the perspective of moving from fossil to renewable resources to produce fine chemicals, the conversion of hexoses and pentoses into their corresponding carboxylic acid derivatives has recently received much attention. For example, are considered as very important value-added chemicals from biomass [1]. They can be used as such in the food and pharmaceutical industry, in cosmetics and as a concrete admixture or as building blocks in numerous industrial applications: syntheses of bio-sourced chemicals and polymers, chelating agents, etc. [2,3] For these reasons, different biotechnological and chemical methods for glucose and xylose oxidation into gluconic (gluconate) and xylonic (xylonate) acids have been developed

Results

Discussion

Conclusion