Electrochemical Oxidation of Glycerol to Dihydroxyacetone in Borate Buffer: Enhancing Activity and Selectivity by Borate–Polyol Coordination Chemistry

Abstract

Selective electrochemical oxidation of glycerol, the major byproduct during the biodiesel production process, can not only make biodiesel production more environmentally benign and economically feasible but also generate value-added C3 chemicals that are important for medicinal and cosmetics applications. However, severe C–C bond breakage often occurs, which would lead to low C3 selectivity, especially on earth-abundant, low-cost transition metal electrocatalysts. In this study, by exploiting the coordination ability of borate ions with polyol molecules, we report enhanced and selective electrochemical oxidation of glycerol to ∼85% C3 chemicals (67% for dihydroxyacetone in detected liquid products, with an average production rate of 90 mmol m–2 h–1), using cobalt borate as the electrocatalyst in borate buffer electrolyte. The improved electrochemical activity and selectivity at different borate buffer concentrations and solution pH values have been explicitly correlated with the coordination ability of borate with glycerol under different circumstances, as revealed by 11B NMR spectroscopy studies. The strategy presented herein can be potentially extended to the selective upgrading of a broad scope of biomass-derived sugars and polyols, for producing value-added chemicals on low-cost non-noble metal electrocatalysts.

Predictive control of selective secondary alcohol oxidation of glycerol on NiOOH

“…We note that in addition to a pH difference, our pH 12 solution contains borate while our pH 13 solution does not. Previously, it has been reported that the presence of borate, which is known to form coordination complexes with polyols 42 , can help suppress C–C cleavage during glycerol electrooxidation 30 . Thus, we additionally carried out electrolysis at pH 13 in the presence of the same amount of borate present at pH 12 (Supplementary Fig.…”

“…The majority of previous studies of electrochemical glycerol oxidation have used precious metal (e.g., Pt, Pd, Ag, or Au)-based catalysts 5,6,9,10 , of which only a few have selectively produced DHA (e.g., Bi or Sb modified Pt catalysts) [11][12][13][14][15][16] . As for non-noble metal-containing electrocatalysts, Nibased ones have been the most extensively investigated [17][18][19][20][21][22][23][24][25][26][27][28][29][30] . The active catalyst layer for most of these Ni-based electrocatalysts is NiOOH, which is known for its ability to oxidize primary alcohols to the corresponding carboxylic acids [31][32][33] .…”

Selective Electrooxidation of Biomass‐Derived Alcohols to Aldehydes in a Neutral Medium: Promoted Water Dissociation over a Nickel‐Oxide‐Supported Ruthenium Single‐Atom Catalyst

“…Currently, alkaline electrolyte is the most used medium for the BDAORs, as non‐noble metal‐based catalysts are generally active and durable in such electrolyte. Nevertheless, selective oxidation of biomass‐based alcohols to aldehydes remains less‐explored [17–20] …”

“…Nevertheless, selective oxidation of biomass-based alcohols to aldehydes remains less-explored. [17][18][19][20] The use of alkaline media severely hinders aldehyde synthesis. On one hand, aldehydes suffer from basecatalyzed dimerization or aldol condensation reactions at high pH value.…”

Recovery and utilization of crude glycerol, a biodiesel byproduct

“…ATR can be performed with a variety of feed combinations for effective thermal management. In order to maintain a self- They utilized Gluconobacter oxydans ATCC 621 as the biocatalyst to convert glycerol into dihydroxyacetone Ripoll et al 74 Agar-immobilized Gluconobacter oxydans NBRC 14819 (Gox) was the best heterogeneous biocatalyst, reaching a quantitative production of 50 g L −1 of DHA from glycerol solely in the presence of water Jain et al 75 Using genetic engineering techniques to modify genes in Escherichia coli (E. coli) aimed at increasing DHA production, achieving a maximum theoretical yield of 6.60 g L −1 DHA Oxidation of glycerol to DHA catalyzed by the PtAuPdAg catalyst in alkaline solution; the HPLC results show that the DHA selectivity was 79.6% Huang et al 77 Cobalt borate was used as a catalyst to increase the yield of glycerol oxidation to C3 chemicals, resulting in 67% DHA in the liquid product and an average yield of 90 mmol m −2 h −1 Tran et al 78 Manganese oxide (MnO 2 ) was utilized as a catalyst for the electrocatalytic glycerol oxidation, which reached the selectivity of 46% for DHA Liu et al 79 They developed a photoelectrochemical system based on nanoporous BiVO4, producing 56 mmol gcatalyst per h of DHA at a potential of 1.2 V vs. RHE under AM 1.5 illumination (100 mW cm −2 )…”