Valorization Of Glycerol Research Articles

Acceptorless Dehydrogenation of Glycerol Catalysed by Ir(III) Complexes with Carbohydrate‐Functionalised Ligands: A Sweet Pathway to Produce Hydrogen and Lactic Acid

AbstractGlycerol, a by‐product of biodiesel production, has gained prominence as a precious platform chemical. To enhance the economic viability of the biodiesel production process and address the surplus of glycerol production, it is essential to transform it into value‐added products. In this context, homogeneous catalysis offers a promising avenue for glycerol valorisation. In this study, we introduce a family of iridium complexes bearing picolineamidate ligands with glucose‐functionalised substituents as novel homogeneous catalysts for glycerol to hydrogen and lactic acid conversion. These complexes exhibit high activity (conversion up to 53.3 %) and 99 % selectivity after 24 hours of reaction (TOFMAX=159 h−1, TON24h=2498). Notably, the reaction occurs under ambient air and at milder temperature conditions (120 °C) compared to other catalysts. These efforts in glycerol valorisation contribute to reducing biodiesel production costs, increasing the competitiveness of biofuels against petroleum‐based liquid fuels, giving rise to H2, through a global process with negative carbon dioxide emission, and lactic acid utilizable, among other, as a monomer for the synthesis of biodegradable plastics.

Towards valorization of glycerol and molasses: Carbon-based catalysts from molasses for the synthesis of acetins

Towards valorization of glycerol and molasses: Carbon-based catalysts from molasses for the synthesis of acetins

Towards value-added chemicals: Technical and environmental life cycle assessment evaluation of different glycerol valorisation pathways

Biodiesel is acknowledged as the most appropriate biofuel to decarbonise the transport sector and combat climate change. The ever-increasing biodiesel production via transesterification results in large amount of glycerol (e.g., 10 kg of glycerol for every 100 kg of biodiesel). Converting glycerol into value-added goods is perceived to be a viable way to lower the high cost of producing biodiesel and expand its market share. The current study examines the technical and environmental aspects of bio-hydrogen, bio-syngas, acrolein, propylene glycol, epichlorohydrin, bio-methanol and bio-ethanol synthesis. CHEMCAD process simulation software was used to perform the modelling and simulation aspects considering a glycerol flowrate of 100 kg/h. The environmental study is based on primary and secondary data and is carried out using the Life Cycle Assessment methodology and the LCA for Experts software, using ReCiPe as the impact assessment method. The technical evaluation points towards glycerol conversion to propylene glycol and bio-methanol production as the best approaches given the relatively low energy requirements, increased purity (>97 wt%) and steadily growing product market. Bio-methanol exhibits the best environmental performance among all examined scenarios, providing the lowest impact in eight out of eleven categories studied while placing second in terms of FETP impact. Glycerol conversion towards propylene glycol seems as the second-best conversion route as it generates the lowest score in regards to GWP impact (0.31 kg CO2 eq./ kgproduct). Ultimately, the most effective methods for valorizing glycerol and improving the production of biodiesel by lowering the expenses related to its manufacturing are glycerol reforming toward bio-methanol and propylene glycol.

Valorization of biodiesel-derived crude glycerol for simultaneous biosynthesis of biodegradable polyhydroxybutyrate and exopolysaccharide by the newly isolated Burkholderia sp. SCN-KJ

This study demonstrated that Burkholderia sp. SCN-KJ is a promising novel species for the biovalorization of crude glycerol to polyhydroxybutyrate (PHB) and galactose-rich heteroexopolysaccharide (EPS). Whole-genome and genetic evolution analyses revealed separation of the different clades according to the ANIb and dDDH analyses, which confirmed that Burkholderia sp. SCN-KJ is a novel species. The highest PHB production from crude glycerol was 12.9 ± 0.4 g/L (72.9 ± 2.1 % w/w), with a productivity of 0.46 g/L/h and YP/S of 0.3 g/g at 28 h in a 10 L fermenter. The galactose-rich hetero-EPS began to be produced after nitrogen depletion, resulting in a concentration of 22.4 ± 0.2 g/L at 38 h. Examination of the carbon-to‑nitrogen ratio (C/N) showed that nitrogen-rich condition (C/N 20) was optimal for PHB production, whereas nitrogen-depleted condition promoted EPS production, showing two different extrema. The findings showed that Burkholderia sp. SCN-KJ has the potential to transform the landscape of biovalorization for sustainable production.

Hierarchically Structured CuNiP/CuOx‐VP Nanoarrays Construction by Heteroatom Doping Boosting Glycerol Valorization at Industrial‐Level Current Density

AbstractElectrocatalytic valorization of glycerol to formate is considered to be a promising sustainable approach; however, it holds great challenges to increase catalyst activity and deliver market‐demanded chemicals with high Faradaic efficiency (FE) and selectivity under industrial‐level current density. Herein, hierarchically structured phosphorus vacancy‐enriched nickel phosphide porous nanoarrays by copper doping, denoted as CuNiP/CuOx‐VP, are constructed via a facile glycol‐mediated solvothermal approach. The CuNiP/CuOx‐VP yields an industry‐level 1 A cm−2 at the ultralow potential of 1.75 V, while showing notable FE (96.94%) and selectivity (96.76%) to formate over a wide range of potentials. Impressively, a two‐electrode electrolyzer linked to H2 evolution possesses exceptional activity that merely requires a cell voltage of 1.45 V to deliver 40 mA cm−2, exhibiting a high FE (97.53%) for formate production and surpassing the vast majority of previously reported precious metal electrocatalysts. Microscopic and electrochemical characterizations manifest that the CuNiP/CuOx‐VP composed of porous NiP nanosheets attached to aggregated CuOx particles featuring superaerophobic‐hydrophilic morphology enables increased active sites, favorable electronic redistribution, and thus boosted electrocatalytic performance. This study demonstrates an effective nanoarrays electrode for catalyst discovery, going from facile catalyst synthesis to structure‐activity relationship and subsequently developing more highly active electrocatalysts for energy‐saving coproduction of valuable chemicals.

Earth-Abundant CuWO4 as a Versatile Platform for Photoelectrochemical Valorization of Soluble Biomass Under Benign Conditions.

Here, a nanosheet-structured CuWO4 (nanoCuWO4) is demonstrated as a selective and stable photoanode for biomass valorization in neutral and near-neutral solutions. nanoCuWO4 can be readily prepared by a solid phase reaction using nanosheet-structured WO3 as the template. Several substrates, including glucose, fructose and glycerol, are investigated to reveal the wide applicability of nanoCuWO4. The activity and product distribution trends in biomass valorization are investigated at different pH by taking advantage of the promising stability of nanoCuWO4 in a wide pH range. Product analyses confirm that formate production with a Faradaic efficiency (FE) of 76 ± 5% and glycolate production with an FE of 61 ± 8% can be achieved by glucose and fructose valorization at pH 10.2, respectively. On the other hand, glyceraldehyde and dihydroxyacetone (DHA)are the main products in the glycerol valorization, accounting for an FE of over 85% at pH 7. Notably, nanoCuWO4 has the highest FE of DHA in photoelectrochemical (PEC)glycerol valorization compared to WO3 and BiVO4 at neutral pH. The oxidation routes and mechanism of glycerol valorization on nanoCuWO4 are also under investigation. The co-production of H2 and value-added chemicals is finally demonstrated using a photovoltaic cell connected to a nanoCuWO4-based PEC glycerol valorization system.

Valorization of Biodiesel-Derived Crude Glycerol for Producing Yeast Oil as an Alternative Biodiesel Production Feedstock: Productivity Improvement in Batch and Repeated Batch Fermentation

Valorization of Biodiesel-Derived Crude Glycerol for Producing Yeast Oil as an Alternative Biodiesel Production Feedstock: Productivity Improvement in Batch and Repeated Batch Fermentation

Valorization of Glycerol to Glycerol Carbonate and Glycidol by Different Dialkyl Carbonates Utilizing Tricalcium Aluminate Hexahydrate as Transesterification Catalyst

AbstractIn this study, we report a base‐catalyzed transesterification reaction of glycerol, a waste product of the biodiesel industry, with various dialkyl carbonates, which act both as reactants and solvents, to convert glycerol carbonate into an industrially useful molecular building block. The catalyst, being used for the first time, is also a waste product from industry, present in bauxite residues and in the Portland cement, simply known as tricalcium aluminate. Despite being well‐known and readily available, this solid is only extremely poorly researched catalyst, nevertheless, using dimethyl and diethyl carbonate, glycerol conversion rates >80% and glycerol carbonate yields >60% could be achieved in just 1 h (under air atmosphere and reflux). In a comparison of the performance with other catalysts commonly researched today, as well as with other components of red mud and cements, the results showed that tricalcium aluminate is excellent, cheap, and largely environmentally friendly material for this purpose. Reusability studies of the catalysts have also shown that they provide high conversion and product yields even after repeated use, although different material characterization techniques showed intense glycerol‐catalyst surface interaction and intermediate product formation, the deactivating side effects of which could be avoided by catalyst regeneration steps.

Comparative Life Cycle Assessment of Glycerol Valorization Routes to 1,2- and 1,3-Propanediol Based on Process Modeling

Comparative Life Cycle Assessment of Glycerol Valorization Routes to 1,2- and 1,3-Propanediol Based on Process Modeling

N‐Heterocyclic Carbene–Based Catalysts for Glycerol Valorisation: Current State and Perspectives

ABSTRACTN‐Heterocyclic carbenes (NHCs) are molecules with exceptional catalytic properties in a wide range of reactions. Recently, there has been a growing interest in using them as catalysts for biomass conversion. In this review, we examine the current state of glycerol valorisation (GV) using several catalytic systems, including metallic complexes bearing NHCs as ligands, polymeric building blocks and organocatalysts. The study covers literature published in the last 15 years, detailing the catalyst scope, reaction conditions and products of GV. This analysis emphasises the importance of varying the steric and electronic properties of NHCs within the reviewed catalytic systems. Furthermore, a critical evaluation of the proposed mechanistic pathways complements these results. A comprehensive understanding of the challenges of using such catalytic systems will emerge by compiling literature on the use of NHCs for the studied reactions. Additionally, this will promote new opportunities for further research in both academic and industrial fields.

Application of Box-Behnken design in monoglycerides production via glycerolysis of palm oil using homogenizer reactor

The glycerolysis of triglycerides (TG) to produce monoglycerides (MG) is an important pathway for glycerol valorization. However, mass transfer resistance has significantly hindered the process efficiency because the reaction is a two-phase liquid-liquid reaction. In this study, a homogenizer was used as a high shear mixing reactor (HSM) to address such issue of mass transfer resistance, and was compared to a conventional mechanically stirred reactor (MS). The effects of the rotational speed, catalyst amount, molar ratio of Gly-to-TG, reaction temperature and reaction time on MG yield were investigated using NaOH as a homogeneous catalyst. Three reaction variables were investigated by statistical analysis using the Box-Behnken (BBK) experimental design, including Gly-to-TG molar ratio (2:1–4:1), catalyst loading (0.1–0.3 wt% TG), and reaction time (15–45 min). The results indicated that the predicted maximum MG yield of 63.4 % was achieved at a reaction time of 29 min, a Gly-to-TG molar ratio of 2.7:1, and a catalyst loading of 0.274 wt% of TG, which agreed with the experimental results. The yield efficiency of HSM was 1.27×10−4 g/J, which was 9.14-fold higher than that of MS at 1.39×10−5 g/J.

Synthesis of Solketal Catalyzed by Acid-Modified Pyrolytic Carbon Black from Waste Tires.

Solketal, a widely used glycerol-derived solvent, can be efficiently synthesized through heterogeneous catalysis, thus avoiding the significant product losses typically encountered with aqueous work-up in homogeneous catalysis. This study explores the catalytic synthesis of solketal using solid acid catalysts derived from recovered carbon blacks (rCBs), which are obtained through the pyrolysis of end-of-life tires. This was further converted into solid acid catalysts through the introduction of acidic functional groups using concentrated H2SO4 or 4-benzenediazonium sulfonate (BDS) as sulfonating agents. Additionally, post-pyrolytic rCB treated with glucose and subsequently sulfonated with sulfuric acid was also prepared. Comprehensive characterization of the initial and modified rCBs was performed using techniques such as elemental analysis, powder X-ray diffraction, thermogravimetric analysis, a back titration method, and both scanning and transmission electron microscopy, along with X-ray photoelectron spectroscopy. The catalytic performance of these samples was evaluated through the batch mode glycerol acetalization to produce solketal. The modified rCBs exhibited substantial catalytic activity, achieving high glycerol conversions (approximately 90%) and high solketal selectivity (around 95%) within 30 min at 40 °C. This notable activity was attributed to the presence of -SO3H groups on the surface of the functionalized rCBs. Reusability tests indicated that only rCBs modified with glucose demonstrated acceptable catalytic stability in subsequent acetalization cycles. The findings underscore the potential of utilizing end-of-life tires to produce effective acid catalysts for glycerol valorization processes.

Crystallization kinetics as a tool to fine-tune the catalytic activity of Na-LTA zeolite precursors in the transesterification of glycerol to glycerol carbonate

Glycerol carbonate is a versatile molecule used as a fuel additive and a chemical building block. It is a prominent route for glycerol valorization, improving the biodiesel production chain. This base-catalyzed reaction can be carried out using sodium-type zeolites if accessibility to the basic sites is ensured. Herein, we report a facile strategy to fine-tune the number and access to basic sites of Na-LTA zeolite precursors via monitoring the crystallization kinetics of the microporous material. It is demonstrated that an optimal glycerol to glycerol carbonate conversion is obtained when using the solid obtained at the beginning of the crystallization (90 min at 100 °C of hydrothermal step). Textural and spectroscopy characterization reveals that semicrystalline material presents many basic aluminate anions in a very open structure, allowing facile access to glycerol and propylene carbonate. Moreover, it is shown that this catalyst is stable in four successive reaction cycles and active in different reactions conditions

Transformation of by-product silicon tetrachloride to an efficient and stable heterogeneous base catalyst: Valorization of glycerol into valuable glycerol carbonate

The by-product silicon tetrachloride (SiCl4) from the polysilicon industry was recycled to fabricate a highly efficient and stable lithium silicate (LS) catalyst for upgrading of oversupplied biodiesel by-product glycerol to valuable glycerol carbonate (GC). The characteristics of the LS catalyst were systematically investigated by various experimental characterization techniques and density functional theory (DFT) calculations. The experimental results showed that the hydrolysis of SiCl4 in the lithium nitrate solution helping to the solid phase synthesis of the LS catalyst as lithium could be uniformly dispersed in the silica gel. The as-synthesized LS catalyst mainly consists of lithium orthosilicate with strong basic sties, favoring the catalytic conversion of glycerol. The LS catalyst exhibited an appreciably high catalytic efficiency (turnover frequency of 2.72 min−1) and glycerol conversion (99.8±1.8 %) compared to other reported solid base catalysts. The apparent activation energy (Ea) of this reaction was calculated to be 39.51 kJ/mol. Further, benefiting from the stable silicate structure, the LS catalyst showed an enhanced catalytic stability as the glycerol conversion declined less than 5 % after five times reuse without regeneration. The LS catalyst also revealed marked resistance to the solid base catalyst poisons like water and methanol compare to that of commercial calcium-based catalyst. The temperature-programmed desorption of CO2 (CO2-TPD) and DFT results affirmed that the low-coordination lattice oxygen of the isolated SiO4 tetrahedron on the surface of the LS catalyst acting as a strong basic electron donor promoted the transesterification reaction between DMC and glycerol. As a result, the SiCl4-derived LS catalyst possessed remarkable catalytic efficiency and reusability, which could be an ideal candidate to meet the requirements for industrial application and highlight the potential application of the by-product SiCl4.

Electrochemical Conversion of Low-Cost Glycerol to Valuable Products

Over the last years, biodiesel production, a renewable fuel derived from biomass, has significantly increased, reaching an output of 40 million tons annually. This surge in production has resulted in excessive glycerol production, as a byproduct, accounting for 10 wt.% of biodiesel production. By 2025, it is predicted that glycerol production will amount to 6.3 million tons.1 However, the low demand for glycerol not only causes high disposal costs for this waste byproduct but also poses a threat to the ecosystem. Consequently, the valorization of glycerol is crucial for enhancing the biodiesel industry's economic viability and environmental sustainability.Among all the techniques for the valorization of glycerol, such as catalytic oxidation, dehydration, and hydrogenolysis, the electrochemical oxidation of glycerol stands out for its cost-effectiveness, simplicity, and eco-friendliness. The glycerol electrooxidation reaction (GOR) can yield a wide range of valuable chemicals, such as C3 products (glyceraldehyde, lactic acid, glyceric acid, tartronic acid), C2 products (glycolic acid, oxalic acid, acetic acid), and C1 products (formic acid). Among all the products, C3 products have notably higher economic value compared to others. In particular, glyceric acid stood out by having a price of over 200 folds of glycerol and having the highest worldwide demand among all the GOR products.2 However, a significant technical challenge lies in developing a highly selective catalyst for C3 products showing high activity, and stability. Thus far, most of the catalyst developed for GOR includes noble metals or their alloys, which limits their usage in realistic systems due to their high cost and scarcity.3 Therefore, developing a cost-effective catalyst with high selectivity, activity, and stability is necessary to make the valorization of glycerol economically viable.In this work, we demonstrate a bimetallic catalyst that, despite its low noble metal content, achieves high selectivity towards glyceric acid, along with notable catalytic activity and stability. Our analysis focuses on the impact of noble metal amount on activity and stability, and parametric analysis to improve the selectivity of C3 products. Furthermore, we outline the reasons for the discrepancies in the quantification of GOR products, especially in applying H-NMR analysis, and discuss the methods to improve the precision in GOR product analysis.

Electrooxidation of Poly(methyl-methacrylate) and Poly(ethylene glycol): Hydrogen Production from Plastic Wastes Electrolysis

Introduction. Green H2 production by water electrolysis at low temperature has some bottlenecks mostly dealing with the anodic reaction, the oxygen evolution reaction (OER), given its thermodynamic and kinetic limitations [1]. One strategy to reduce the energy requirements for this H2 production route is the replacement of the conventional OER (with a thermodynamic potential of 1.23 V vs. Reversible Hydrogen Electrode (RHE)) by a less-energy intensive reaction like the electrooxidation of organic molecules (in some cases presenting a thermodynamic potential as low as c.a. 0 V vs RHE). This approach also addresses the possibility of converting organic wastes into value-added chemicals avoiding the CO2 emissions derived from conventional treatments (e.g., incineration) [2, 3]. Our research group is focused on the electrochemical valorization of several organic wastes like polyethylene glycol (PEG) or poly(methyl-methacrylate) (PMMA). Both are commonly found in urban and industrial water effluents and concern has been raised about the true fate of these polymers in the environment. Herein, the possibility of generating H2 and value-added organic molecules from these plastic wastes has been explored. Experimental. A binary solvent strategy was followed to dissolve the PMMA polymer, by using 1 M H2SO4 in 80% v/v 2-propanol/water electrolyte. Then the electrooxidation of PMMA was studied in a 2-electrode batch cell at 70ºC with different PMMA concentrations (0.1-2 wt.%). On the other hand, the electrooxidation of ethylene glycol (EG) and PEG with various molecular weights (from 200 to 4000 g mol-1), which are soluble in water, was carried out in aqueous solutions (PEG concentrations from 1 to 20 g/L) between 30 and 80 °C by using a Polymer Electrolyte Membrane (PEM) reactor. Pt/C electrodes were used in all cases. A commercial Pt cathode was employed and the anode material was prepared by the spray-deposition of a Pt(20 wt.%)/C catalyst powder onto a carbon paper gas-diffusion layer. The liquid products at the anodic compartment were analysed by size-exclusion chromatography (SEC) and nuclear magnetic resonance (NMR) spectroscopy while the production of hydrogen in the cathodic compartment was online monitored with a mass spectroscopy. Results and discussion. In the case of PMMA electrooxidation, despite the dissolution challenge, polymer macromolecules showed to partially block the accessibility of the Pt active sites on the electrode and strongly degraded its electrochemical performance [4]. In the case of PEG, it was much more easily electrooxidised, at low cell voltages, from around 0.4 V at 80°C (Figure 1a), near to values recorded with EG, suggesting a first step linked with the electrooxidation of the terminal groups of the macromolecules chain. Current densities larger than 100 mA.cm-2 at 0.8 V and 80°C were achieved for low molecular mass molecules (200 and 400 g/mol). A decrease of the PEG molecular weight in the anodic solution was demonstrated by SEC, confirming that the electro-oxidation process likely follows two main mechanisms, involving the consumption of terminal –OH or intermediate -C-O-C- bonds cleavage (Figure 1b), depending on the polymer molecular weight. This study demonstrates the proof-of-concept of the low-temperature electro-oxidation of polymers containing C-O bonds in their main chain. Conclusions. With a further macroporous electrode enegineering and catalyst development, the electrolysis of plastic wastes stands as a promising technology not only for the production of hydrogen from macromolecules by electrochemical means, but also as a potential pathway to depolymarize plastic wastes, thus increasing their degradability. References. [1]. Y. Cheng, S.P. Jiang, Advances in electrocatalysts for oxygen evolution reaction of water electrolysis-from metal oxides to carbon nanotubes, Prog. Nat. Sci.: Mater. 25 (2015) 545-553.[2]. M. Simões, S. Baranton, C. Coutanceau, Electrochemical valorisation of glycerol, ChemSusChem. 5 (2012) 2106–2124[3]. Y.X. Chen, A. Lavacchi, H.A. Miller, M. Bevilacqua, J. Filippi, M. Innocenti, et al. Nanotechnology makes biomass electrolysis more energy efficient than water electrolysis. Nat. Commun. 5 (2014) 1-6.[4]. N. Grimaldos-Osorio, F. Sordello, M. Passananti, J. González-Cobos, A. Bonhommé, P. Vernoux, A. Caravaca. From plastic-waste to H2: A first approach to the electrochemical reforming of dissolved Poly(methyl methacrylate) particles. Int. J. Hydrogen Energy. 48 (2023) 11899-11913. Acknowledgments The authors gratefully acknowledge the French institution “Ecole Urbaine de Lyon” (EUL - Institut de Convergences) for funding a PhD grant of Dr. N. Grimaldos-Osorio. Figure 1

Photoelectrochemical Oxidation of Glycerol over g-C3N4 Nanosheets Coupled with Metal-Assisted Hybrid Carbon Quantum Dots

Carbon quantum dots (CDs) are the most promising candidates of the carbon family with a size of less than 10nm. They owned superior properties such as high solubility in aqueous medium, low toxicity, biocompatibility, stable photoluminescence, spectral convertor, and act as electron reservoirs. These properties make CDs suitable for photo-electrochemical catalytic applications. Low quantum yield and activity in the visible light spectrum of CDs may restrict their applicability. To address this issue, doping and surface passivation of CDs is the only approach to improve their physicochemical characteristics, visible light absorption, and quantum yield by altering their size and structure. Metals are electron-efficient entities and act as electron donors. As a result, when metal ions are doped into CDs, the charge density and charge transition between the core of the CDs and the metal ions increases. This results in a greater improvement in the physicochemical properties of CDs as compared to non-metal doping[1]. Metal-assisted CDs i.e. hybrid CDs tend to modulate energy band positions, change the electronic structure, increase quantum yield, and generate new emissive traps in CDs. The photoluminescence property of CDs can be enhanced due to the surface plasmonic resonance (SPR) effects of metal nanoparticles (NPs). Hybrid CDs also show better catalytic performance as compared to the pristine CDs. It helps to enhance the active sites on the CDs surface to facilitate catalytic performance.By keeping these properties, the hybrid CDs were effectively utilized in the field of dye decolorization, degradation of water pollutants, storage materials, and as a sensor[2][3]. The photo-assisted electrochemical glycerol valorization is one of the prominent methods for producing value-added chemicals such as glycolic acid. However, it is a challenge to achieve high yield and selectivity of products. This research investigated the fabrication of heterojunction of g-C3N4 (CN) with CDs and Bi-assisted CDs (BiCD) as a sustainable photoactive material. The heterojunction was obtained by incorporating CDs and BiCD (5wt.% each) onto CN nanosheets by in-situ thermal polymerization treatment and named CDCN and BiCDCN. The prepared composite was analyzed by structural (XRD), functional (XPS) microscopic (FESEM, FETEM) spectroscopic (UV-Vis, PL, TRPL, EDS), and photoelectrochemical characterization techniques.The band gap of CN was obtained as 2.78 eV which was reduced to 2.69 eV for CDCN and 2.62eV for BiCDCN, increasing the absorbance in the visible light zone. The existence of CDs and BiCDs was confirmed by, FETEM investigation (Fig.1a). The XPS analysis of the composite revealed the presence of Bi 4f chemical state of bismuth metal. The calculated TRPL lifetime was 0.28ns for BiCDCN and 2.51 ns for CDCN which was lower than that of CN (9.31 ns) suggesting the rapid electron transfer ability of BiCDCN. In the presence of light and glycerol, the composite BiCDCN had the maximum photocurrent density of 12 mA/cm2, followed by CDCN (1.6 mA/cm2) and CN (1.3 mA/cm2) at 1.2 V. The photoelectrochemical oxidation of glycerol was performed at 0.8V for 3h. The detected products were glycolic acid, glyceric, glyoxylic acid, and oxalic acid. The addition of CD to CN increased the glycerol conversion and yield of glycolic acid & glyoxylic acid significantly. The composite exhibited 43% selectivity towards glycolic acid and 34% for glyoxylic acid. The glycerol conversion and yield of these two products were further enhanced by Bi doping. BiCDCN had a total glycerol conversion of 21%, followed by CDCN at 5.7% and CN at 3.8%. The BiCDCN had the highest yield of glycolic acid at 8.9 % and that for CDCN was 2.4 % and 1.2 % for CN (Fig.1b). The glyoxylic acid yield was 7.2%, 2.2%, and 0.8% for BiCDCN, CDCN, and CN, respectively. Figure 1

A red-light-powered silicon nanowire biophotochemical diode for simultaneous CO2 reduction and glycerol valorization

A red-light-powered silicon nanowire biophotochemical diode for simultaneous CO2 reduction and glycerol valorization

Metabolic versatility of anaerobic sludge towards platform chemical production from waste glycerol

Waste glycerol is produced in excess by several industries, such as during biodiesel production. In this work, the metabolic versatility of anaerobic sludge was explored towards waste glycerol valorization. By applying different environmental (methanogenic and sulfate-reducing) conditions, three distinct microbial cultures were obtained from the same inoculum (anaerobic granular sludge), with high microbial specialization, within three different phyla (Thermodesulfobacteriota, Euryarchaeota and Pseudomonadota). The cultures are capable of glycerol conversion through different pathways: (i) glycerol conversion to methane by a bacterium closely related to Solidesulfovibrio alcoholivorans (99.8% 16S rRNA gene identity), in syntrophic relationship with Methanofollis liminatans (98.8% identity), (ii) fermentation to propionate by Propionivibrio pelophilus strain asp66 (98.6% identity), with a propionate yield of 0.88 mmol mmol−1 (0.71 mg mg−1) and a propionate purity of 80–97% and (iii) acetate production coupled to sulfate reduction by Desulfolutivibrio sulfoxidireducens (98.3% identity). In conclusion, starting from the same inoculum, we could drive the metabolic and functional potential of the microbiota towards the formation of several valuable products that can be used in industrial applications or as energy carriers.Key pointsVersatility of anaerobic cultures was explored for waste glycerol valorizationDifferent environmental conditions lead to metabolic specializationBiocommodities such as propionate, acetate and methane were produced

Unveiling the catalytic potential of K2ZnF6 fluoroperovskite for glycerol oligomerization

AbstractThis study systematically evaluates fluorine‐containing materials with varying compositions of K, Al, Co, Cu, Mg, and Zn as catalysts for glycerol oligomerization. Comprehensive analyses were conducted for all of the catalysts, considering their structural, compositional, morphological characteristics, and basicity, to understand them in greater depth. Among these analyses, gas chromatography was employed to examine the composition of the reaction products. The investigation extended to a recycling study under optimized conditions. Thermogravimetric analysis and X‐ray photoelectron spectroscopy were used to characterize the spent catalysts. Catalytic activity was found to be influenced strongly by the fluorine content, demonstrating remarkable performance for the materials containing fluoroperovskites such as KMgF3 in the catalyst KMgAFC, and K2ZnF6 in KZAFC. Remarkably, KZAFC with 20% fluorine exhibited superior glycerol conversion (68%) and selectivity for diglycerol (27%). Comparative analysis with ZnAl‐layered double hydroxide highlighted the positive impact of fluorine on catalytic activity. Introducing a calcination step in the catalyst recovery process also demonstrated improved activity during recycling. Interestingly, KZAFC exhibited stability over four reaction cycles, presenting an economic advantage over homogeneous catalysts. The study also shed light on the potential fluorine loss at the surface and potassium leaching into reaction products, correlating these phenomena with the observed decline in activity. These comprehensive findings contribute significantly to advancing sustainable glycerol valorization through heterogeneous catalysis.