Production Of Renewable Fuels Research Articles

Dried distiller’s grains in the diets of feedlot lambs: implications for production, carcass characteristics and rumen morphometrics

Context The demand and production of renewable fuels are boosting the production of biofuels. Agricultural industries have been playing a role in the increase of ethanol production from corn and, consequently, their by-products. Dried distiller’s grain (DDG) is a by-product of corn ethanol and can be used as a source of protein and energy in the diet of feedlot lambs. Aims The objectives of this experiment were to evaluate the effects of including DDG in high-concentrate diets on performance, rumen morpho-histology, and carcass characteristics in feedlot lambs. Methods Forty-five Santa Inês × Dorper male lambs with an initial body weight of 21 ± 3.2 kg (mean ± s.d.) and 82 ± 12 days old (mean ± s.d.) were distributed in a randomised complete-block design (nine blocks and five treatments). The experimental diets contained 900 g/kg of concentrate and 100 g/kg of coastcross hay, and DDG was used in replacement of soybean meal and corn. Lambs were fed one of the following five diets for 112 days: control without DDG (0DDG), or diet with 150 (150DDG), 300 (300DDG), 450 (450DDG) and 600 (600DDG) g/kg DM of DDG. Key results The inclusion of DDG from 150 up to 600 g/kg DM in the diet of the lambs linearly decreased (P < 0.01) dry-matter intake (DMI), net energy of maintenance intake, net energy of gain, average daily gain, final body weight and feed efficiency (P < 0.01). The inclusion of DDG linearly decreased (P ≤ 0.04) hot carcass weight, cold carcass weight, hot carcass yield and cold carcass yield. For ruminal morpho-histology, there was a linear decrease in the area of papillae and absorptive surface area (P < 0.01) Conclusions An increase in the DDG level from 150 to 600 g/kg DM in the diet of lambs negatively affected feedlot performance, with detrimental effects on carcass traits and the development of rumen papillae. The lambs showed low acceptance of DDG, even at the lowest level of dietary inclusion (150g/kg DM) as DMI was impaired. Implications DDG should be used with caution in diets for finishing lambs. Dietary inclusion of DDG up to 150 g/kg DM is recommended. Higher inclusions levels may significantly affect performance and carcass weight and yield.

Influence of SnWO4, SnW3O9, and WO3 Phases in Tin Tungstate Films on Photoelectrochemical Water Oxidation.

An essential step toward enabling the production of renewable and cost-efficient fuels is an improved understanding of the performance of energy conversion materials. In recent years, there has been growing interest in ternary metal oxides. Particularly, α-SnWO4 exhibited promising properties for application to photoelectrochemical (PEC) water splitting. However, the number of corresponding studies remains limited, and a deeper understanding of the physical and chemical processes in α-SnWO4 is necessary. To date, charge-carrier generation, separation, and transfer have not been exhaustively studied for SnWO4-based photoelectrodes. All of these processes depend on the phase composition, not only α-SnWO4 but also on the related phases SnW3O9 and WO3, as well as on their spatial distributions resulting from the coating synthesis. In the present work, these processes in different phases of tin tungstate films were investigated by transient surface photovoltage (TSPV) spectroscopy to complement the analysis of the applicability of α-SnWO4 thin films for practical PEC oxygen evolution. Pure α-SnWO4 films exhibit higher photoactivities than those of films containing secondary SnW3O9 and WO3 phases due to the higher recombination of charge carriers when these phases are present.

The Development of Metal-Free Porous Organic Polymers for Sustainable Carbon Dioxide Photoreduction.

A viable tactic to effectively address the climate crisis is the production of renewable fuels via photocatalytic reactions using solar energy and available resources like carbon dioxide (CO2) and water. Organic polymer material-based photocatalytic materials are thought to be one way to convert solar energy into valuable chemicals and other solar fuels. The use of porous organic polymers (POPs) for CO2 fixation and capture and sequestration to produce beneficial compounds to reduce global warming is still receiving a lot of interest. Visible light-responsive organic photopolymers that are functionally designed and include a large number of heteroatoms and an extended π-conjugation allow for the generation of photogenerated charge carriers, improved absorption of visible light, increased charge separation, and decreased charge recombination during photocatalysis. Due to their rigid structure, high surface area, flexible pore size, permanent porosity, and adaptability of the backbone for the intended purpose, POPs have drawn more and more attention. These qualities have been shown to be highly advantageous for numerous sustainable applications. POPs may be broadly categorized as crystalline or amorphous according to how much long-range order they possess. In terms of performance, conducting POPs outperform inorganic semiconductors and typical organic dyes. They are light-harvesting materials with remarkable optical characteristics, photostability, cheap cost, and low cytotoxicity. Through cocatalyst loading and morphological tweaking, this review presents optimization options for POPs preparation techniques. We provide an analysis of the ways in which the preparative techniques will affect the materials' physicochemical characteristics and, consequently, their catalytic activity. An inventory of experimental methods is provided for characterizing POPs' optical, morphological, electrochemical, and catalytic characteristics. The focus of this review is to thoroughly investigate the photochemistry of these polymeric organic photocatalysts with an emphasis on understanding the processes of internal charge generation and transport within POPs. The review covers several types of amorphous POP materials, including those based on conjugated microporous polymers (CMPs), inherent microporosity polymers, hyper-crosslinked polymers, and porous aromatic frameworks. Additionally, common synthetic approaches for these materials are briefly discussed.

Electrocatalytic Conversion of Phenol to Cyclohexane Using Pt and Ru-Based Catalysts

The production of renewable fuels has become necessary as fossil fuels continue to deplete.1 Pyrolysis of biomass to liquid fuels has emerged as a promising solution due to the possibility of conversion of high carbon content feedstocks into fuel. Pyrolysis oils, however, struggle from low yields and increased heteroatom content.2 In order to solve this problem a second upgrading step is needed to increase the fuel’s hydrogen content and remove heteroatoms. Conventional oil upgrading through thermochemical processes is an option using high temperatures (>300 °C) and high-pressure hydrogen (10-20MPa).3 Electrochemical upgrading of bio-oils represents a novel avenue for the conversion of bio-oils to usable fuels or commodity chemicals under mild condition which requires milder temperatures (30-80 °C) and generates the hydrogen in situ through the water splitting reaction.3 Though initial results on electrocatalytic upgrading have been promising, few studies report appreciable yields of fully deoxygenated products and the efficiency remains low at high current densities.3 This work focuses on the upgrading of phenol as a bio-oil model compound. ECH of phenol was investigated in a custom electrochemical cell (H-Cell), with a solvent trap for the collection and quantification of volatile organic products. Efficient ECH conversion of phenol to cyclohexane was demonstrated and the primary factors impacting the selective production of cyclohexane were studied. Multiple variables, including catalyst type, electrolyte composition and concentration, and cathodic potential were investigated to determine their influence on ECH reaction rate, selectivity, and efficiency. The results obtained show that lab-synthesized, bi-metallic PtRu-C catalyst results in the highest specific ECH rate of 23.52 mol h-1 g-1 metal in comparison to 19.92 mol h-1 g-1 metal, 15.84 mol h-1 g-1 metal and 4.64 mol h-1 g-1 metal, measured with a commercial PtRu-C and mono-metallic Pt-C and Ru-C catalysts, respectively. In addition, the lab synthesized PtRu-C catalyst achieved > 30% selectivity towards cyclohexane, which is among the highest reported in literature to date. Constant potential experiments showed that the cyclohexane was 4.6% higher at -0.46 V vs Ag/AgCl than -0.28 V vs Ag/AgCl indicating cyclohexane selectivity is weakly dependent on cathodic potential. To improve the mechanistic understanding of phenol ECH, operando Raman spectroscopy was explored, finding strong evidence for cyclohexanone reaction intermediates.References(1) Zhang, X.; Lei, H.; Chen, S.; Wu, J. Catalytic Co-Pyrolysis of Lignocellulosic Biomass with Polymers: A Critical Review. Green Chemistry. 2016. https://doi.org/10.1039/c6gc00911e.(2) Zhang, B.; Zhong, Z.; Min, M.; Ding, K.; Xie, Q.; Ruan, R. Catalytic Fast Co-Pyrolysis of Biomass and Food Waste to Produce Aromatics: Analytical Py-GC/MS Study. Bioresour. Technol. 2015, 189. https://doi.org/10.1016/j.biortech.2015.03.092.(3) Chen, G.; Liang, L.; Li, N.; Lu, X.; Yan, B.; Cheng, Z. Upgrading of Bio-Oil Model Compounds and Bio-Crude into Biofuel by Electrocatalysis: A Review. ChemSusChem. 2021. https://doi.org/10.1002/cssc.202002063. Figure 1

Electrocatalytic Upgrading of Biomass-Derived Compounds for Biofuel Production

Biomass fast pyrolysis liquid (also known as bio-oil) is considered to be one of the most promising renewable carbon feedstocks. However, fresh pyrolyzed bio-oil is acidic and corrosive and contains large amounts of carbonyl and phenolic compounds produced by polymerization under acidic conditions. This work primarily utilizes an electrochemical conversion strategy using only earth-abundant metal catalysts to achieve the carbonyl hydrogenation process. The results show that upgrading this process produces biofuels with greater stability and higher specific energy. In addition to analyzing the chemical implications of this conversion strategy, this work will also discuss why electrocatalytic conversion is a promising technology path for biofuels and fine chemicals. Reference Huang, S., Lam, C. H.* et al. (2022). "The Structural Phase Effect of MoS2 in Controlling the Reaction Selectivity between Electrocatalytic Hydrogenation and Dimerization of Furfural." ACS Catalysis 12(18): 11340-11354.Huang, S., Lam, C. H.* et al. (2022). "MoS2-Catalyzed Selective Electrocatalytic Hydrogenation of Aromatic Aldehydes in an Aqueous Environment." Green Chemistry.Tu, Q., Lam, C. H.* et al. (2021). "Electrocatalysis for Chemical and Fuel Production: Investigating Climate Change Mitigation Potential and Economic Feasibility." Environmental Science & Technology 55(5): 3240-3249.Garedew, M., Lam, C. H.* et al. (2020). "Greener Routes to Biomass Waste Valorization: Lignin Transformation Through Electrocatalysis for Renewable Chemicals and Fuels Production." ChemSusChem 13(17): 4214-4237. Lam, C. H., et al. (2017). "Towards sustainable hydrocarbon fuels with biomass fast pyrolysis oil and electrocatalytic upgrading." Sustainable Energy & Fuels 1(2): 258-266. Figure 1

Aggregation of Homogeneous Porphyrin Catalysts in Organic Electrolyte Broadly Inhibits Electrochemical CO2 Reduction Performance

Metalloporphyrins are widely used as homogeneous electrocatalysts for the production of renewable fuels from abundant feedstocks and sustainable energy. The modularity of porphyrin catalysts has led to the establishment of structure‐function correlations that aid in predicting and optimizing catalytic activity. Although metalloporphyrins are widely known to aggregate due to their planar structure that promotes π–π stacking, it is surprising that the influence of metalloporphyrin aggregation on electrocatalytic performance has not been previously investigated. Herein, we will document the relative aggregation and electrocatalytic activity for CO2 reduction to CO with three structurally related iron meso-phenylporphyrins in commonly used N,N-dimethylformamide (DMF) electrolyte. An inverse dependence of kinetics on catalyst concentration is observed for all three porphyrins based on cyclic voltammetry data. Furthermore, this inhibition extends to bulk electrolysis performance, where up to 75% of the catalyst in a 1 mM solution is inactive compared to in a 0.25 mM solution. This talk will additionally discuss how aggregation is influenced by organic additives, axial ligands, redox state, metal identity, and porphyrin substituents. Overall, this work emphasizes that metalloporphyrins can aggregate severely (even in well-solubilizing organic electrolytes) and that aggregation effects must be considered for optimization of performance and for meaningful catalytic activity comparisons.

The Role of Surface Roughening in Improving the Selectivity of Copper for CO2 Electroreduction

Electroreduction of CO2 (eCO2RR) has emerged as a promising alternative for production of renewable fuels and important commodity chemicals such as ethylene and ethanol. Simultaneously, it opens an economically attractive path to mitigate point sources of CO2, a potent greenhouse gas. Despite decades of research efforts, Cu remains the only catalyst capable of producing significant amounts of desirable C2+ products, containing more than one carbon atom. However, further improvement is needed for industrial applications. It is known that roughened copper-based electrocatalysts surfaces exhibit enhanced selectivity towards C2+ products during electroreduction of CO2. This poses a challenge for modeling efforts aiming to find a rationale for the enhanced selectivity. In this work, we use an innovative modeling approach to investigate roughened copper surfaces derived from cuprous oxide on structures of 100x100 nm2 size with atomic resolution and accuracy compared to density functional theory (DFT). We combine semilocal DFT (RPBE) in VASP, effective medium theory (EMT), and linear scaling relationships via the recently proposed alpha parameter scheme to investigate the site-resolved catalytic selectivity of copper sites. Electrode potential-dependence is included via the use of the VASPsol implicit solvation and a grand canonical potential approach. The approach allows us to investigate the effect of varied macroscopic roughness on the intrinsic catalytic activity of copper by comparing surfaces exposed to simulated sputtering and electropolishing, respectively. The study highlights i) the challenge for designing improved copper catalysts for CO2RR with monodisperse active site selectivity, ii) the need for careful experimentation when comparing to theory, and iii) the limitations of macroscopic roughness in controlling atomic scale activity.

(Invited) Tailored Electrochemical Interfaces for Renewable Fuels Production

Tailoring the structure of the electrified interface and the electrocatalytically active sites at the atomic and molecular levels is key to elucidating the design principles to develop advanced materials for sustainable energy conversion and storage. This talk will focus on recent strategies to tune the structure-activity-selectivity relationships for oxygen, carbon dioxide/carbon monoxide and methane electrocatalysis to produce renewable fuels.First, I will present our work toward understanding and tuning the structure-property relations for oxygen evolution for the production of green hydrogen in proton exchange membrane water electrolysers. Then, I will show our model studies on well-defined Cu-based surfaces to understand structure-properties relations for the electrochemcial CO2 reduction reaction. We have investigated the effect of electrolyte, pH, and potential dependence for CO reduction on Cu single crystals as well as methods to evaluate the facet distribution on Cu-based catalysts. Finally, I will discuss some strategies for selective oxidation reactions such as partial oxidation of methane to produce liquid fuels such as methanol.

EU Regulatory Compliance of Renewable Fuels from Steel Mill Gases and Exhaust Gases

AbstractThe production of renewable and sustainable fuels must comply with the EU regulatory framework (Renewable Energy Directive (EU) 2023/2413, Commission Delegated Regulations (EU) 2023/1184, and (EU) 2023/1185) for the use of renewable energy in the transport sector. The utilization of steel mill gases (SMGs) and alternative CO2 sources (waste incineration plants (WIPs), lime industry) to produce renewable fuels of non‐biological origin (RFNBOs) and recycled carbon fuels (RCFs) are attractive options as a high share of RFNBOs can be achieved with a significant reduction in greenhouse gas (GHG) emissions compared to fossil fuel use.

Daniel Esposito.

"The most important future applications of my research are related to the production, use, and storage of renewable fuels… I advise my students to carry out 'Friday afternoon experiments' that may not be 100% aligned with their main project but are curiosity-driven experiments with potential to lead to something new…" Find out more about Daniel Esposito in his Introducing… Profile.

Green iron and syngas production via continuous solar-driven agricultural waste biomass gasification combined with iron(III) oxide reduction

The production of renewable synthetic fuels and chemicals from solar energy and agricultural waste biomass is considered. Solar thermochemical conversion processes offer a promising pathway to a sustainable fuel economy and green chemical industry. This study investigates the continuous solar-driven gasification of agricultural biomass (betel nut waste) combined with iron oxide (Fe2O3) reduction to produce carbon-neutral syngas and green metallic iron in a single process. A thermodynamic analysis of the system was initially conducted to predict the distribution of equilibrium products. Then, on-sun continuous processing was experimentally carried out under different operating conditions, including betel/Fe2O3 molar ratios (0.56–1.5) and temperatures (900–1200 °C) to evaluate the process feasibility and reliability. As a result, solar gasification of betel nut waste combined with Fe2O3 reduction performed exceptionally well with continuous reactant particles feeding, demonstrating a feasible pathway for producing green iron and high-quality syngas. The maximum syngas yield reached 63.3 mmol/gdry_betel, approaching its theoretical value, and high-purity Fe was simultaneously produced. The process demonstrated high efficiency, with maximum carbon conversion approaching 98 %, energy upgrade factor up to 1.26, and solar-to-fuel energy conversion efficiency up to 14.4 %, highlighting remarkable conversion performance of biomass and solar energy to chemicals.

Autotrophic adaptive laboratory evolution of the acetogen Clostridium autoethanogenum delivers the gas-fermenting strain LAbrini with superior growth, products, and robustness

Microbes able to convert gaseous one-carbon (C1) waste feedstocks are increasingly important to transition to the sustainable production of renewable chemicals and fuels. Acetogens are interesting biocatalysts since gas fermentation using Clostridium autoethanogenum has been commercialised. However, most acetogen strains need complex nutrients, display slow growth, and are not robust for bioreactor fermentations. In this work, we used three different and independent adaptive laboratory evolution (ALE) strategies to evolve the wild-type C. autoethanogenum to grow faster, without yeast extract and to be robust in operating continuous bioreactor cultures. Multiple evolved strains with improved phenotypes were isolated on minimal media with one strain, named “LAbrini”, exhibiting superior performance regarding the maximum specific growth rate, product profile, and robustness in continuous cultures. Whole-genome sequencing of the evolved strains identified 25 mutations. Of particular interest are two genes that acquired seven different mutations across the three ALE strategies, potentially as a result of convergent evolution. Reverse genetic engineering of mutations in potentially sporulation-related genes CLAU_3129 (spo0A) and CLAU_1957 recovered all three superior features of our ALE strains through triggering significant proteomic rearrangements. This work provides a robust C. autoethanogenum strain “LAbrini” to accelerate phenotyping and genetic engineering and to better understand acetogen metabolism.

Clocking out and letting go to unleash green biotech applications in a photosynthetic host

Cyanobacteria are photosynthetic bacteria whose gene expression patterns are globally regulated by their circadian (daily) clocks. Due to their ability to use sunlight as their energy source, they are also attractive hosts for "green" production of pharmaceuticals, renewable fuels, and chemicals. However, despite the application of traditional genetic tools such as the identification of strong promoters to enhance the expression of heterologous genes, cyanobacteria have lagged behind other microorganisms such as Escherichia coli and yeast as economically efficient cell factories. The previous approaches have ignored large-scale constraints within cyanobacterial metabolic networks on transcription, predominantly the pervasive control of gene expression by the circadian (daily) clock. Here, we show that reprogramming gene expression by releasing circadian repressor elements in the transcriptional regulatory pathways coupled with inactivation of the central oscillating mechanism enables a dramatic enhancement of expression in cyanobacteria of heterologous genes encoding both catalytically active enzymes and polypeptides of biomedical significance.

Multivariate Bayesian Optimization of CoO Nanoparticles for CO2 Hydrogenation Catalysis.

The hydrogenation of CO2 holds promise for transforming the production of renewable fuels and chemicals. However, the challenge lies in developing robust and selective catalysts for this process. Transition metal oxide catalysts, particularly cobalt oxide, have shown potential for CO2 hydrogenation, with performance heavily reliant on crystal phase and morphology. Achieving precise control over these catalyst attributes through colloidal nanoparticle synthesis could pave the way for catalyst and process advancement. Yet, navigating the complexities of colloidal nanoparticle syntheses, governed by numerous input variables, poses a significant challenge in systematically controlling resultant catalyst features. We present a multivariate Bayesian optimization, coupled with a data-driven classifier, to map the synthetic design space for colloidal CoO nanoparticles and simultaneously optimize them for multiple catalytically relevant features within a target crystalline phase. The optimized experimental conditions yielded small, phase-pure rock salt CoO nanoparticles of uniform size and shape. These optimized nanoparticles were then supported on SiO2 and assessed for thermocatalytic CO2 hydrogenation against larger, polydisperse CoO nanoparticles on SiO2 and a conventionally prepared catalyst. The optimized CoO/SiO2 catalyst consistently exhibited higher activity and CH4 selectivity (ca. 98%) across various pretreatment reduction temperatures as compared to the other catalysts. This remarkable performance was attributed to particle stability and consistent H* surface coverage, even after undergoing the highest temperature reduction, achieving a more stable catalytic species that resists sintering and carbon occlusion.

A design of solar-driven thermochemical reactor integrated with heat recovery for continuous production of renewable fuels

To cope with the increasingly serious energy crisis and environmental problems, the transformation from traditional energy to renewable energy is urgent. Solar-driven thermochemical conversion of CO2 and H2O into renewable fuels technology provides a favorable path for alternative energy. However, the temperature/pressure swing required for the reduction and oxidation steps during thermochemical process incurs irreversible energy losses and severe material stresses. Moreover, the two-step redox cycle mode cannot achieve a continuous fuel production in the reactor. To address these issues, this study proposes a novel design of thermochemical reactor integrated with heat recovery for continuous production of renewable fuels. In this design, an oxygen-conducting ceria membrane is employed to conduct oxygen ions, electrons and vacancies induced by the oxygen chemical potential gradient to achieve an isothermal and continuous splitting of CO2 and H2O. At the fuel production side, a counter-flow and tube-in-tube alumina reticulate porous ceramic filling heat exchange design is developed to recover the sensible heat of gas products and excessive reactants. In addition, a comprehensive model is developed by coupling the computational dynamics of flow, radiation, conduction and convection, and is solved by the Monte Carlo method coupled with ANSYS FLUENT software through User-defined Functions. Results indicate that the integrating membrane reactor/heat recovery design can not only realize continuous production of renewable fuels, but also recover sensible heat of gas products, which is beneficial for conversion of solar energy to chemical energy. Optimizing heat recovery design can help reactor achieve a solar-to-fuel efficiency of 10.58%. Moreover, if the theoretical CO2 conversion rate could be achieved, the solar-to-fuel efficiency of reactor can reach as high as 40.43%, which means that such a reactor design has a huge potential in conversion of solar energy into renewable fuels.

Photocatalytic CO2 Reduction Using an Osmium Complex as a Panchromatic Self‐Photosensitized Catalyst: Utilization of Blue, Green, and Red Light

AbstractThe photocatalytic reduction of carbon dioxide (CO2) represents an attractive approach for solar‐energy storage and leads to the production of renewable fuels and valuable chemicals. Although some osmium (Os) photosensitizers absorb long wavelengths in the visible‐light region, a self‐photosensitized, mononuclear Os catalyst for red‐light‐driven CO2 reduction has not yet been exploited. Here, we discovered that the introduction of an Os metal to a PNNP‐type tetradentate ligand resulted in the absorption of light with longer‐wavelength (350–700 nm) and that can be applied to a panchromatic self‐photosensitized catalyst for CO2 reduction to give mainly carbon monoxide (CO) with a total turnover number (TON) of 625 under photoirradiation (λ≥400 nm). CO2 photoreduction also proceeded under irradiation with blue (λ0=405 nm), green (λ0=525 nm), or red (λ0=630 nm) light to give CO with >90 % selectivity. The quantum efficiency using red light was determined to be 12 % for the generation of CO. A catalytic mechanism is proposed based on the detection of intermediates using various spectroscopic techniques, including transient absorption, electron paramagnetic resonance, and UV/Vis spectroscopy.

Photocatalytic CO2 Reduction Using an Osmium Complex as a Panchromatic Self-Photosensitized Catalyst: Utilization of Blue, Green, and Red Light.

The photocatalytic reduction of carbon dioxide (CO2) represents an attractive approach for solar-energy storage and leads to the production of renewable fuels and valuable chemicals. Although some osmium (Os) photosensitizers absorb long wavelengths in the visible-light region, a self-photosensitized, mononuclear Os catalyst for red-light-driven CO2 reduction has not yet been exploited. Here, we discovered that the introduction of an Os metal to a PNNP-type tetradentate ligand resulted in the absorption of light with longer-wavelength (350-700 nm) and that can be applied to a panchromatic self-photosensitized catalyst for CO2 reduction to give mainly carbon monoxide (CO) with a total turnover number (TON) of 625 under photoirradiation (λ≥400 nm). CO2 photoreduction also proceeded under irradiation with blue (λ0=405 nm), green (λ0=525 nm), or red (λ0=630 nm) light to give CO with >90 % selectivity. The quantum efficiency using red light was determined to be 12 % for the generation of CO. A catalytic mechanism is proposed based on the detection of intermediates using various spectroscopic techniques, including transient absorption, electron paramagnetic resonance, and UV/Vis spectroscopy.

Critical interplay between ruthenium oxide and water for the catalytic conversion of lignin to sustainable aviation fuel

The production of renewable drop-in fuels from lignocellulosic biomass is desirable for achieving net-zero carbon emissions in the transportation sector. However, the high irregularity of lignin and its resistance to complete ring saturation and deoxygenation hinder its conversion to sustainable aviation fuels (SAFs) such as C7–C16 isoparaffins and alkylated cycloalkanes. In this study, we achieve the direct production of SAFs from lignin-derived oil over a nonacidic Ru/C catalyst in water. Hydrogen atoms generated by H2 dissociation combine with neighboring water molecules to produce hydronium ions, which are then transferred via H-shuttling to attack the double bonds and cyclic –OH groups of adsorbed reactants and intermediates. Density functional theory calculations suggest that hydrodeoxygenation in water decreases the activation energy for the direct hydrogenolysis of cyclic –OH groups over oxygen-vacant ruthenium oxide sites. The critical interplay between oxygen-vacant ruthenium oxide and water results in the almost-complete conversion of lignin-derived monomers, dimers, and bio-oils to desirable SAF components.

Techno-economic analysis for the sunlight-powered reverse water gas shift process: Scenarios, costs, and comparative insights

The deployment of renewable chemicals and fuels production is directly connected to technical developments, political incentives and investments. The route towards market competitiveness of such chemicals and fuels requires significant cost reduction from state-of-the-art production and operation. In this manuscript, we estimate to what extent the expected technical improvements of the sunlight-powered reverse water gas shift process catalysed by a Au/TiO2 photocatalyst can improve its economic performance. Multiple factors and different scenarios are explored to identify the main dependencies that drive price reductions for this technology. Our projections indicate that the total capital investments required to deploy this green CO production route have the potential to decline from 325 million euros down to 51 million euros for an annual CO production of 100 kton based on the technical improvements. The levelized cost of CO could decrease from around 205 €/GJ CO to 53 €/GJ CO. These results indicate that sunlight-powered chemistry can become competitive when higher carbon taxes are applied to the production of fossil CO (75-200€/ton CO2).

Amorphous and crystalline heterostructure MoSe2/NiFe-LDH through p-n junction formation for electrochemical water splitting-synergistic back bonding effect

Designing a long-lasting, highly effective, non-noble metal-free electrocatalyst for both hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) is a strenuous task for water electrolysis. Here, in our study, an ordered NiFe-layer double hydroxide (LDH)/MoSe2 as p-n junction material was designed using facile two-step hydrothermal process for the overall water splitting reaction. Additionally, synthesized NiFe-LDH/MoSe2, electrode exhibits long-term durability in both acidic and alkaline medium for HER and OER, respectively. Mott-Schottky experiments provides the insights of interfacial electron transfer, where the electron is transported from n-type NiFe-LDH to p-type MoSe2, resulting in the generation of the p-n junction in MoSe2/NiFe-LDH. As the formation LDH and transition dichalcogenides p-n junction leads to activation of the catalysts towards the OH− adsorption that may enable the water electrolysis with a low overpotential. The XPS analysis supports the electron transfer from Fe to Mo resulting in the formation synergistic back bonding between the p-n heterojunction. This strategy opens up an alternative path to a highly effective, relatively low-price catalyst for the global production of renewable energy fuels.