Figure - available from: Energy Technology
This content is subject to copyright. Terms and conditions apply.
Source publication
Glycerol, as the major by‐product of biodiesel, can be oxidized into diverse value‐added chemical products via either traditional chemical methods or electrochemical route. Glycerol electrooxidation reaction (GOR) driven by renewable‐derived electricity (e.g., windy, solar) is a promising pathway for fine chemicals production. In an electrochemical...
Citations
... Using noble metal catalysts, the overpotential of glycerol oxidation can be lowered 7 , and the reaction can be performed even without C-C cleavage (that is, mainly C3 products can be obtained: Supplementary Note 6 and Supplementary Fig. 17). These catalysts, however, are quickly poisoned by the reaction intermediates (mainly by the adsorbed CO) 7 . To mitigate the poisoning effect of CO, the anode catalyst should either bind CO weakly but still oxidize glycerol, or it should oxidize the adsorbed CO at low potentials. ...
Photoelectrochemistry holds the promise of directly converting sunlight to valuable chemical products. Photoelectrochemical (PEC) methods, however, lag behind their electrochemical counterparts in terms of current density. In this work, we demonstrate that, by using concentrated sunlight, we can achieve current densities similar to electrochemical methods, but with lower energy input. Specifically, we combined the direct PEC oxidation of glycerol with the dark hydrogen evolution or CO2 reduction in a membrane-separated continuous-flow PEC cell. We achieved over 110 mA cm⁻² photocurrent density, which is at least an order of magnitude larger than those typically reported in the literature. We demonstrated that the product distribution of glycerol oxidation is notably different in PEC and electrochemical scenarios at the same current density, and the parasitic oxygen evolution reaction can be suppressed in the PEC case. This approach raises opportunities to drive complex electrochemical reactions in a more selective manner.
... Noble metals (e.g., Pt, Pd, and Au) exhibit excellent glycerol electro-oxidation reaction (GEOR) activity, such as a low onset potential, high selectivity for C3 products, and good corrosion resistance [16][17][18] . Among these, platinum is the most popular catalyst for glycerol oxidation owing to its strong catalytic activity in both acidic and alkaline environments 17 . ...
... Noble metals (e.g., Pt, Pd, and Au) exhibit excellent glycerol electro-oxidation reaction (GEOR) activity, such as a low onset potential, high selectivity for C3 products, and good corrosion resistance [16][17][18] . Among these, platinum is the most popular catalyst for glycerol oxidation owing to its strong catalytic activity in both acidic and alkaline environments 17 . However, applying an oxidation potential and prolonged electrolysis can result in PtO x formation, hindering the adsorption of OH adsorbate (OH ad ) and alcohol substrate 19,20 . ...
Preventing the deactivation of noble metal-based catalysts due to self-oxidation and poisonous adsorption is a significant challenge in organic electro-oxidation. In this study, we employ a pulsed potential electrolysis strategy for the selective electrocatalytic oxidation of glycerol to glyceric acid over a Pt-based catalyst. In situ Fourier-transform infrared spectroscopy, quasi-in situ X-ray photoelectron spectroscopy, and finite element simulations reveal that the pulsed potential could tailor the catalyst’s oxidation and surface micro-environment. This prevents the overaccumulation of poisoning intermediate species and frees up active sites for the re-adsorption of OH adsorbate and glycerol. The pulsed potential electrolysis strategy results in a higher glyceric acid selectivity (81.8%) than constant-potential electrocatalysis with 0.7 V RHE (37.8%). This work offers an efficient strategy to mitigate the deactivation of noble metal-based electrocatalysts.
... In this case, at low mass transport, the accessibility to Pt active sites is limited, leading to lower reactivity and glycerol conversion rate. Besides, low mass transport results in the dihydroxyactone and glyceraldehyde intermediates hard to desorb from the Pt surface, which on the one hand, limits the chemical dehydration of dihydroxyactone, [16] while on the other hand, promotes the over electrooxidation of the glyceraldehyde towards glyceric acid and other oxidation products [32][33][34]. ...
... Explanations for the effects of temperature on the electrochemical oxidation of glycerol have also been proposed in the literature. According to Fan et al, the glycerol oxidation reaction is much like thermal activation processes, meaning that higher temperatures have a positive effect on glycerol's reactivity in the reaction [33]. Lee et al provide insight on a molecular level, stating that higher temperatures improve glycerol oxidation performance by facilitating the adsorption of OH species onto the catalyst, and consequently the dissociation of O-H and C-H bonds [37]. ...
Among various electrochemical reactions to produce fuels and chemicals, glycerol electrolysis to co-produce hydrogen and lactic acid has received great attention. However, studies have shown the benchmark Pt based catalysts are insufficient in selectively catalysing the glycerol to lactic acid transformation, resulting in a low yield of lactic acid. Here we report a study on glycerol electrolysis with anion-exchange membrane electrode assembly electrolyser. The reaction conditions including mass transport, temperature, current density and KOH concentration were optimised, among which temperature played a significant role in facilitating the reaction rate and thermodynamics. With the optimised condition a multicomponent Pt/C-zeolite electrocatalyst system (Pt/C-CBV600) was developed and tested, which is capable to increase the lactic acid selectivity to 57.3% from the 33.8% with standalone Pt/C. Although the detailed mechanism required further investigation, it is hypothesised that the CBV600 zeolite with abundant Lewis acid surface sites can effectively bind the dihydroxyacetone intermediate, and drive the reaction towards pyruvaldehyde heterogeneously, the key step to form lactic acid.
... 甘油氧化反应(glycerol oxidation reaction, GOR)是一个多电子转移过程 [86] , 一 般分为两种反应路线, 如图7(a)所示: 一种是甘油通过 C-C键的裂解和醇通过质子耦合电子转移氧化为醛或 羧酸, 将羟基氧化成醛或羧酸; 另一种是甘油转化为甘 油醛和乙醇醛中间体后合成甲酸, 理论上FE可达到 100%. 然而, 由于其低的电氧化动力学和高破坏C-C 键的能垒, 甘油很难完全氧化, 实现高选择性催化合成 目标产物仍是巨大的挑战 [87] . He等人 [88] 报道了NiCo氢氧化物的GOR性能(图7(b)). ...
... Electrocatalysts are required for reducing the activation energy of glycerol electrooxidation. Several studies have described promising strategies for designing and constructing efficient electrocatalysts, in which the final concept combines the production of high-value chemicals with the production of hydrogen in electrolysis cells [2,[4][5][6][7][8][9]. These strategies suggest considering increasing the intrinsic activity of a catalyst's active site and increasing its number of active sites. ...
The electrocatalytic oxidation of glycerol by metal electrocatalysts is an effective method of low-energy-input hydrogen production in membrane reactors in alkaline conditions. The aim of the present study is to examine the proof of concept for the gamma-radiolysis-assisted direct growth of monometallic gold and bimetallic gold–silver nanostructured particles. We revised the gamma radiolysis procedure to generate free-standing Au and Au-Ag nano- and micro-structured particles onto a gas diffusion electrode by the immersion of the substrate in the reaction mixture. The metal particles were synthesized by radiolysis on a flat carbon paper in the presence of capping agents. We have integrated different methods (SEM, EDX, XPS, XRD, ICP-OES, CV, and EIS) to examine in detail the as-synthesized materials and interrogate their electrocatalytic efficiency for glycerol oxidation under baseline conditions to establish a structure–performance relationship. The developed strategy can be easily extended to the synthesis by radiolysis of other types of ready-to-use metal electrocatalysts as advanced electrode materials for heterogeneous catalysis.
... Catalytic glycerol oxidation is a promising method to produce a variety of valueadded products and can be performed by electrocatalysis, thermal catalysis, and biological catalysis [13]. Among the various methods of glycerol oxidation, electrocatalytic glycerol oxidation reaction (EGOR) technology is a promising way to generate valuable chemicalssuch as dihydroxyacetone (DHA), glyceraldehyde (GAD), glyceric acid (GLA), tartronic Figure 1a shows X-ray diffraction (XRD) patterns of 20 wt% Pt/C and PtCu/C catalysts. ...
... Figure 3b shows the high-resolution Cu 2p spectra that present the assigned Cu 2p 3/2 and Cu 2p 1/2 doublet as Cu 0 (932. 13 Cu 2+ species near the surface [49,50]. The high-resolution O 1s spectra consisting of three deconvoluted peaks assigned to O 2− (530.93 and 530.48 eV), C-O (532.38 and 532.18 eV), and C=O (533.71 and 533.58 eV) bonds did not show substantial differences between the Pt/C and PtCu/C catalysts in Figure 3c. ...
... Catalysts 2023, 13, 892 ...
In this work, we show that finding and controlling optimum pH environments with Pt-based alloy catalysts can create high catalytic performances for electrocatalytic glycerol oxidation reaction (EGOR). Compared to a Pt/C catalyst, the PtCu/C alloy catalyst has higher reaction rate and turnover frequency (TOF) values by increasing the pH. Specifically, the reaction rate and TOF of the PtCu/C catalyst at pH 13 were 2.93 and 6.65 times higher than those of Pt/C, respectively. The PtCu/C catalyst also showed lower onset potential value and higher mass and specific activities than the Pt/C by increasing the pH. This indicates that the Cu in the PtCu alloy improves the catalytic activity for the EGOR in an OH− group-rich environment. In the case of the PtCu/C catalyst at a high pH condition, the selectivities of tartronic acid and oxalic acid tended to increase as the selectivity of lactic acid decreased. This result means that the PtCu alloy follows primary alcohol oxidation pathways, which are more favorable in an OH− group-rich environment than with only Pt. This study proposes that it is critical to optimize and control the reaction conditions for developing efficient EGOR catalysts.
... Glycerol, a renewable, low-cost, and widely available compound, is a waste product from the transesterification of vegetable oils for biodiesel production-10% m/m of the products is glycerol [1][2][3][4]. Given that the rate of world biodiesel production is high, new applications for glycerol as a platform molecule for the chemical industry must be found [2][3][4][5]. The industrial demand for value-added products, including C3 compounds such as glyceric acid, tartronic acid, glyceraldehyde, dihydroxyacetone, hydroxypyruvic acid, and mesoxalic acid derived from glycerol oxidation, is high because these compounds have numerous commercial applications. ...
... The industrial demand for value-added products, including C3 compounds such as glyceric acid, tartronic acid, glyceraldehyde, dihydroxyacetone, hydroxypyruvic acid, and mesoxalic acid derived from glycerol oxidation, is high because these compounds have numerous commercial applications. They are mainly used in the manufacture of biodegradable polymers and as emulsifiers or raw materials for organic synthesis, so they have high market values [4,5]. In addition, glyceric acid can be used to prepare medicines to treat skin diseases, and it can be employed as an intermediate in serine amino acid synthesis and as an anionic monomer for packaging material, not to mention other medicinal applications [4][5][6]. ...
... They are mainly used in the manufacture of biodegradable polymers and as emulsifiers or raw materials for organic synthesis, so they have high market values [4,5]. In addition, glyceric acid can be used to prepare medicines to treat skin diseases, and it can be employed as an intermediate in serine amino acid synthesis and as an anionic monomer for packaging material, not to mention other medicinal applications [4][5][6]. ...
We have investigated platinum catalysts containing iron as a modifier to obtain catalysts with superior electrocatalytic activity toward glycerol electro-oxidation in an alkaline medium. The electrocatalysts, supported on carbon Vulcan, were synthesized by the polyol method. The physicochemical characterization data showed that the metals were well distributed on the carbon support and had small particle size (2 nm). The Pt:Fe metal ratio differed from the nominal composition, indicating that reducing iron with platinum was difficult, even though some parameters of the synthesis process were changed. Electrochemical analyses revealed that PtFe/C was more active and stable than commercial Pt/C was, and analysis of the electrolysis by-products showed that iron addition to Pt/C boosted the glycerol conversion and selectivity for glyceric acid formation.
... Various valuable products with one to three carbon atoms can be obtained by GOR, making GOR often referred to as a type of electroreforming, in which gaining control over reaction selectivity becomes critically important. [2,3] On non-noble metal-based electrocatalysts, glycerol usually undergoes CÀ C cleavage in an alkaline environment, which generates a mixture of C1, C2, and C3 products, with formic acid being the major product. [4][5][6][7][8][9][10][11] Although there are reports of the preparation of non-formic acid products based on nonnoble metal electrocatalysts, especially at near neutral pH, [12][13][14][15] the formation of high yields of C3 products in the alkaline electrolyte, remains challenging. ...
Abstract The glycerol oxidation reaction (GOR) has high potential in substituting the oxygen evolution reaction (OER) in electrochemical water splitting, enabling the synthesis of value‐added organic products. The Cu‐rich Cu−Co hydroxycarbonates show high activity in GOR and promote formate production but undergo severe Cu leaching in the presence of deprotonated glycerol. In this work, the electrooxidation of solketal (SOR), acetal‐protected glycerol, is explored over a series of Cu−Co hydroxycarbonates, to promote the formation of glycerol‐derived C3 products, such as glyceric acid, with faradaic efficiencies of around 70 %, and to limit the Cu leaching from the catalyst. The competition between OER and SOR was evaluated using rotating disk electrodes and differential electrochemical mass spectrometry. Insights into the solketal de‐acetalization as a function of potential are obtained using in situ spectroscopic methods. The solketal/OH− ratio influences the reaction selectivity, with oxalate production increasing when 7 m KOH is used instead of 1 m KOH.
... [22,23] However, glycerol can be partly oxidized to various value-added C 3 -products such as dihydroxyacetone and glyceric acid which offer interesting properties for biogenic monomers. [24][25][26] Hence, this work will focus on acidic conditions to preserve the CÀ C bonds and avoid side reactions of aldehydes and ketones lowering carbon retention in the products. ...
Glycerol electrooxidation is a promising alternative to oxygen evolution as an anodic reaction for efficient hydrogen production. However, the performance of electrocatalysts in this reaction is still limited by CO poisoning and products of lower value form due to C−C cleavage. In this study, PtCu/C catalysts with different metal ratios were investigated for glycerol electrooxidation in acidic media. The addition of Cu to the benchmark Pt/C catalyst increased the activity, productivity, as well as stability due to electronic and structural effects. The best performer Pt7Cu3/C showed an increase in mass activity of 56 %. Lower accumulation of intermediates was proven in electrolysis experiments, leading to an increased selectivity of 90 % to valuable C3‐products. The combined methodology of comprehensive electrochemical characterization and application in electrolysis experiments provides a practical approach for improving glycerol assisted hydrogen production addressing major challenges such as CO poisoning and stability. A bimetallic electrocatalyst: PtCu/C catalysts for glycerol electrooxidation coupled with hydrogen production in acidic media. Catalysts are synthesized by a microwave assisted polyol method, characterized physically and electrochemically, and applied to an electrolysis cell. The formation of a PtCu alloy enabled higher activity, productivity, and selectivity to valuable C3‐products.
... Glycerol can be oxidized into numerous valuable chemicals used in many different industries. The potential products include formic acid/formate, which can be utilized as a fuel in fuel cells, as an anti-icing agent and as a food or rubber additive [15,16]. The market price of formic acid (85 wt.%) was around 0.6-0.8 ...
A mixed Co and Ni boride precursor was synthesized via chemical reduction and subsequently annealed at 400 or 500 °C with or without prior addition of the monomer benzoxazine. The resulting mixed CoNiB materials were investigated as electrocatalysts for three alcohol oxidation reactions (AOR) in alkaline electrolyte: the oxidation of glycerol (GOR), ethylene glycol (EGOR) and ethanol (EOR). Comparison of the rotating disk electrode (RDE) cyclic voltammograms for the different catalysts revealed that CoNiB annealed at 500 °C without the addition of benzoxazine exhibited the lowest overpotentials in AORs at 10 mA cm–2, promoting GOR at 224 ± 6 mV lower potential compared to OER. When pyrolysis was conducted at 400 0 °C, the benzoxazine-containing catalyst showed a significant increase in the electrocatalytic activity for the AORs compared to the CoNiB catalyst only. The product selectivity on the different catalysts was investigated in a batch-type reactor with flow recirculation revealing formate as the main oxidation product during GOR and EGOR with faradaic efficiencies (FE) in a range of 60 – 80 %, while acetate was obtained during EOR (FE ~ 85 – 90 %). The electrode potential, electrolyte composition and the type of ionomer were explored with respect to their influence on the GOR selectivity. The use of different ionomers resulted in significant differences in the activity trends between RDE and the batch-type reactor with flow recirculation measurements, indicating a strong influence of the two different substrates used, namely glassy carbon and carbon paper on the catalyst formation and thus on the recorded electrochemical activity.
