Enhancing Glycerol Conversion and Selectivity toward Glycolic Acid via Precise Nanostructuring of Electrocatalysts

Abstract

The glycerol electro-oxidation reaction (GEOR) can economically convert glycerol, a byproduct of biodiesel production, to glycolic acid. Herein, nanostructured Au catalysts were fabricated on a Si substrate by the electrochemical reduction of anodic-treated (RA-treatment) Au films, which tuned the surface area from 1 to 16 cm2. Treatment of 0.1 M glycerol at 1.0 V (vs RHE) for 2 h in 1 M KOH solution afforded a glycerol conversion and glycolic acid selectivity of 50.9 and 47%, respectively. The RA-Au catalyst selectively afforded glycolic acid from glycerol due to the enhanced facet-dependent OH adsorption, especially at the (100) and (110) sites, as well as the increased surface area. RA treatment of a Au-coated Ni foam further enhanced the GEOR performance, affording 68.7% glycerol conversion and 41.2% glycolic acid selectivity at 1.0 V (vs RHE) within 2 h by providing more active sites.

Electrocatalytic Upcycling of Biomass and Plastic Wastes to Biodegradable Polymer Monomers and Hydrogen Fuel at High Current Densities

“…Considering the activity of Au for the selective electrooxidation of GLY/EG under lower potential (∼0.85 V vs RHE), , and the catalytic performance of Ni­(OH) 2 for formate production under high potential (∼1.4 V vs RHE) as reported previously, our initial design was to incorporate Au and Ni­(OH) 2 and obtain a bifunctional catalyst that can afford different product selectivities in the electrooxidation of GLY/EG at varied potentials. To this end, Au particles supported on the Ni­(OH) 2 nanosheet array were prepared as the electrocatalyst.…”

Advanced (photo)electrocatalytic approaches to substitute the use of fossil fuels in chemical production

“…No one addressed the tandem electrolyser with glycerol to GC on the anode side and oxalic acid to GC on the cathodic side. However, separate studies on these two reactions have been reported on glycerol to GC electro-oxidation, [184][185][186][187] and oxalic acid to GC electro-reduction. [188][189][190][191] It may be argued that in organic chemistry, the stable product of glycerol oxidation is glyceraldehyde, which quickly isomerises to dihydroxyacetone.…”

“…No one addressed the tandem electrolyser with glycerol to GC on the anode side and oxalic acid to GC on the cathodic side. However, separate studies on these two reactions have been reported on glycerol to GC electro-oxidation, 184–187 and oxalic acid to GC electro-reduction. 188–191…”

“…However, various authors demonstrate the feasibility of the electro-oxidation of glycerol to GC. [184][185][186][187] Kim et al 184 used nanostructured Au catalysts at the anode of an electrochemical cell, reporting a glycerol conversion of B51% and GC selectivity B47% at 1.0 V (vs. RHE). The selectivity to GC was attributed to the enhanced facet-dependent OH adsorption, especially at the ( 100) and (110) sites.…”

Recent advances in the utilization of glycerol for the production of lactic acid by catalysis

“…Meanwhile, using chemicals synthesized from bio‐based glycerol to substitute for fossil‐based chemicals will bring environmental benefits. Many feasible protocols, including oxidation, dehydration, acetylation, esterification, reforming, reduction, etherification, ammoxidation and acetalization, have been applied in glycerol conversion, 6–9 owing to its highly functionalized molecular structure containing three hydroxyl groups. Various useful and valuable chemicals such as lactic acid, citric acid, 1,3‐dihydroxyacetone, propanol, propanediols, glycerol esters, solketal, oligomers, acrolein, hydrogen, glyceric acid, acetin and ethanol can be produced from glycerol 10–13 .…”