Fuel Precursors Research Articles

Selective Synthesis of Renewable Diesel Fuel Precursors via C–C Condensation of Biomass-Derived Furans Using a Niobium Oxide Nanocatalyst

Selective Synthesis of Renewable Diesel Fuel Precursors via C–C Condensation of Biomass-Derived Furans Using a Niobium Oxide Nanocatalyst

Exploring Impurity Effects and Catalyst Surface Features in Furfural Electroreduction for Jet Fuel Precursor Production: Experimental and Molecular Dynamics Insights

Exploring Impurity Effects and Catalyst Surface Features in Furfural Electroreduction for Jet Fuel Precursor Production: Experimental and Molecular Dynamics Insights

Amine-Modified Polyacrylonitrile as Catalysts for the C–C Coupling of Furfural to High-Carbon Fuel Precursors

Amine-Modified Polyacrylonitrile as Catalysts for the C–C Coupling of Furfural to High-Carbon Fuel Precursors

Efficient Self-Condensation of Cyclohexanone into Biojet Fuel Precursors over Sulfonic Acid-Modified Silicas: Insights on the Effect of Pore Size and Structure.

Mesoporous silica materials with different pore structures and sizes have been used for supporting aryl sulfonic acid catalytic sites via a postsynthetic grafting approach. The synthesized materials have been evaluated in the solventless acid-catalyzed self-condensation of cyclohexanone (CHO) to obtain the corresponding C12 adducts. These compounds display great potential as oxygenated fuel precursors as they can be transformed into jet fuel range alkanes in a subsequent hydrodeoxygenation process. In this work, the synthesized catalysts have displayed high selectivity values toward monocondensed compounds (>95%), thus limiting the formation of undesired heavier condensation products, together with CHO conversion values in the range 20-40% after 2 h of reaction at 100 °C. The structural and textural properties of the supports play an important role in the catalytic performance. Moreover, the activity per acid center is correlated with the textural properties of the supports, indicating that a lower surface density of the anchored aryl sulfonic groups affords an improvement in their specific activity. Finally, the benefit of using supports with large pore sizes and open structures, which limit the fouling of the catalysts by organic deposits, is demonstrated in a stability and reusability test.

Plasma-Activated Solid Base Carbon Monolith Catalyst for Continuous Synthesis of High-Density Aviation Fuel Precursors

Plasma-Activated Solid Base Carbon Monolith Catalyst for Continuous Synthesis of High-Density Aviation Fuel Precursors

Electroreductive C–C Coupling of Furfural to Jet Fuel Precursors in Neutral Media via Synergistic Catalysis of the Polyoxotungstate and Cu Complex

Electroreductive C–C Coupling of Furfural to Jet Fuel Precursors in Neutral Media via Synergistic Catalysis of the Polyoxotungstate and Cu Complex

Co-pyrolytic drivers and volatiles of 3D printing waste and textile dyeing sludge and their multi-objective optimization

Textile dyeing sludge (TDS) disposal poses a critical environmental challenge due to its complex and hazardous nature. This study explored the co-pyrolysis of 3D printing waste (3DPW), comprising photosensitive resin waste (PRW) and polycaprolactone waste (PCLW), with TDS as a potential co-circularity strategy. Drivers, interactions, and resultant products of the co-pyrolysis were characterized through thermogravimetric experiments. Kinetically, the co-pyrolysis process followed a second-order reaction (F2) model. The co-pyrolysis with PRW enhanced the releases of ketones, aldehydes, and esters, with 2-pentene (26.70%) and 2-ethylacrolein (34.67%) as the primary products. Conversely, the co-pyrolysis with PCLW reduced CO emission and generated tetrahydrofuran (27.28%) and cyclopentanone (44.58%). The co-pyrolysis with 3DPW offers a promising approach for mitigating environmental pollution by transforming hazardous wastes into value-added valuable precursors for fuels and organic chemicals.

Catalytic Valorization of Sugarcane Bagasse to Chemicals and Aviation Fuel Precursors

Catalytic Valorization of Sugarcane Bagasse to Chemicals and Aviation Fuel Precursors

Semi-continuous hydrothermal processing of pine sawdust for integrated production of fuels precursors and platform chemicals

This research reports data for the integrated obtaining of fermentable sugars (FSs), bio-oil (BO), and hydro-char (HC) – all fuel precursors – as well as platform chemicals (PCs – acetic, formic, and levulinic acid, besides furfural, and hydroxymethylfurfural) through semi-continuous hydrothermal processing of sawdust from pine wood. The influence of temperature (260, 300, and 340 °C) and the water-to-biomass ratio (25 and 50 g H2O (g biomass)−1) were the parameters considered to evaluate the mass yields, kinetic profiles, and BO properties. For FSs (and PCs), a detailed analysis considering the kinetic profiles of obtaining cellobiose, glucose, xylose, and arabinose is presented. For the conditions evaluated, a distinct behavior concerning the process parameters was observed, where 7.11 and 9.28 g (100 g biomass)−1 of FSs and PCs were synergistically obtained, respectively, after 30 min, 20 MPa, 260 °C, and 50 g H2O (g biomass)−1. Contextually, 17.59 g (100 g biomass)−1 of BO was obtained at 340 °C and the same water/biomass ratio. FTIR analysis of the BO samples suggested the presence of aldehydes, carboxylic acids, ketones, hydrocarbons, ethers as well as aromatic, alcohols, and nitrogenous compounds. Similar HC yields were achieved among the conditions analyzed, where 24.68 g (100 g biomass)−1 were obtained at 340 °C and 50 g H2O (g biomass)−1 for a higher heating value of 29.14 MJ kg−1 (1.5 times higher than the in natura biomass).

Synthesis of Long Chain Oxygenates via Aldol Condensation of Furfural and Acetone over Metal-Organic Frameworks.

Enormous efforts have been made to convert biomass to liquid fuels and products catalytically. Long molecules with a suitable structure are ideal precursors for fuels and value-added products. Here, a C21 oxygenate was synthesized for the first time in one step through aldol condensation of furfural and acetone over the amine-functionalized zirconium-based metal-organic framework (MOF), UiO-66-NH2. Structural changes of UiO-66-NH2 were investigated to improve the yield and evaluate the role of the ligand, cluster node, defectiveness, modulator, surface area, and textural properties on the product distribution. We demonstrate the possibility of making long-chain oxygenates without using vegetable oil-derived fatty acids toward 100% waste biomass-derived renewable fuels, lubricants, and surfactants.

Novel Sulfonic Acid Functionalized Silica Supported Isonicotinic Acid Catalyst for Conversion of 2-Methylfuran to Diesel Fuel Precursors

Novel Sulfonic Acid Functionalized Silica Supported Isonicotinic Acid Catalyst for Conversion of 2-Methylfuran to Diesel Fuel Precursors

Assessing feasible H2–CO2 sources in the US as Feedstocks for Sustainable Aviation Fuel Precursors: Acetic Acid and Ethanol Production via Hydrogenotrophic Pathways

The environmental impact of carbon dioxide emissions is significant, and research is focused on mitigating these emissions and developing eco-friendly technologies in line with green chemistry principles. Waste-to-energy technologies play a crucial role in converting waste into renewable energy and valuable biofuels and bioproducts. This study specifically explores the utilization of waste gas emissions, particularly carbon dioxide, from various sources in the United States for the production of sustainable aviation fuel (SAF) precursors, such as ethanol and acetic acid. The study categorizes and quantifies the volumes of carbon dioxide emissions into three types: non-biogenic, biogenic, and biogenic emissions from ethanol production facilities. Stoichiometric calculations are applied to compare the amounts of carbon dioxide from each category with the available hydrogen production capacity, determining if sufficient hydrogen is present for converting carbon dioxide into SAF precursors. The study reveals two key findings. Firstly, there is a significant reserve of carbon dioxide, approximately 1648 million metric tons per year (MMTy), combining all three categories, which would require a substantial increase of approximately 35–40 times in the existing hydrogen production capacity of 4.988 MMTy. This increased hydrogen production has the potential to yield approximately 1067.82 MMTy of acetic acid and 189.19 MMTy of ethanol annually. Secondly, upon analyzing the quality and application of the three sources of carbon dioxide with the currently available hydrogen production capacity, it is found that biogenic carbon dioxide from ethanol plants is the most suitable choice for immediate production of SAF precursors. This would theoretically result in an annual production of 1.36 MMTy of ethanol and 1.772 MMTy of acetic acid. The other two sources of carbon dioxide can be considered potential reserves for future utilization when additional hydrogen production facilities are established.The study provides a foundation for assessing the aggregation potential required for acetic acid and ethanol production. By optimizing the use of waste gases as raw materials, the study not only enables the production of SAF precursors but also contributes to the passive reduction of greenhouse gas emissions.

Enhanced Upgrading of Crude Lignin Bio-Oil to Jet Fuel Precursors with a Moderate Organic Acid-Modified Copper Catalyst

Enhanced Upgrading of Crude Lignin Bio-Oil to Jet Fuel Precursors with a Moderate Organic Acid-Modified Copper Catalyst

Selective Synthesis of Renewable Bio-Jet Fuel Precursors from Furfural and 2-Butanone via Heterogeneously Catalyzed Aldol Condensation

This study aims to synthesize α,β-unsaturated carbonyl compounds with branched structures via aldol condensation of furfural and 2-butanone using magnesium–aluminum (MgAl) mixed oxides as heterogeneous acid–base catalysts. Regarding the molecular structure of 2-butanone, there are two possible enolate ions generated by subtracting the α-hydrogen atoms at the methyl or methylene groups of 2-butanone. The branched-chain C9 products, derived from the methylene enolate ion, can be applied as bio-jet fuel precursors. The most suitable catalyst, contributing the highest furfural conversion (63%) and selectivity of the branched-chain C9 products (77%), is LDO3, the mixed oxides with 3:1 Mg:Al atomic ratio, with a high surface area and a large number of medium basic sites. The suitable reaction conditions to produce the branched-chain C9 ketones are 1:5 furfural:2-butanone molar ratio, 5 wt.% catalyst loading, 120 °C reaction temperature, and 8 h reaction time. Additionally, this study investigates the adsorption of 2-butanone onto a mixed oxide using in situ Fourier transform infrared spectroscopy; the results of which suggest that the methylene enolate of 2-butanone is the likely dominant surface intermediate at elevated temperatures. Accordingly, the calculation, based on density functional theory, indicates that the methylene enolate ion of 2-butanone is the kinetically favorable intermediate on an MgO(100) as a model oxide surface.

Rapid Synthesis of Diesel Precursors from Biomass-Derived Furanics Over Aluminum-Doped Mesoporous Silica Sphere Catalysts.

The condensation of biomass-derived molecules has been increasingly utilized as a sustainable strategy for the preparation of high-carbon precursors for high-density fuels, thus stimulating the demand for more efficient catalysts. This study concerns the synthesis of an aluminum-doped mesoporous silica sphere (Al-MSS) catalyst for the conversion of biobased furfural and 2-methylfuran into a C15 diesel precursor through a hydroxyalkylation/alkylation (HAA) reaction. A series of Al-MSS catalysts with different Si/Al ratios and calcination temperatures is prepared and extensively characterized, among which Al-MSS20-450 (Si/Al=20 : 1, calcined at 450 °C) exhibits unprecedentedly high reaction efficiency in catalyzing HAA reaction, offering a 94 % product yield at 140 °C in 20 min. The catalyst also gives high product yields across a broad temperature range from 80 °C to 140 °C with varied reaction time. Reaction kinetics reveal that both competitive substrate adsorption and temperature-dependent system viscosity affect the reaction efficiencies. Correlations between the catalytic activity and surface acid sites disclose that moderate and strong acid sites are primarily responsible for catalysis. Brønsted and Lewis acid sites are found by poisoning assays to work synergistically to catalyze the reaction, with the former being the primary sites. Finally, the catalyst displays good recycling performance, which further highlights its potential for industrial application.

Electrochemical Hydrodimerization of Furfural in Organic Media as an Efficient Route to Jet Fuel Precursor

AbstractUpgrading biomass‐derived compounds to value‐added products, especially fuels, represents a green route alternative to fossil fuels energy sources. Here, we report an efficient electrosynthesis of a jet fuel precursor hydrofuroin from furfural, which is one of the most valuable compounds derived from biomass. Despite the high value of this process, few studies have been focused on the development of synthetic strategies for electrocatalytic hydrodimerization of furfural to hydrofuroin. In this work, we systematically examine how operating parameters, including the electrolyte, applied potential, furfural concentration, and catalyst nature affect the efficiency of hydrofuroin electrosynthesis in organic media. We show that under the optimized conditions, the electrosynthesis can be carried out in a simple undivided cell with a high faradaic efficiency (up to 74 %) and an excellent hydrofuroin yield (up to 100 %).

Cover Feature: Electrochemical Hydrodimerization of Furfural in Organic Media as an Efficient Route to Jet Fuel Precursor (ChemElectroChem 2/2023)

The Cover Feature illustrates that biomass-derived furfural can be electrochemically converted to a jet fuel precursor. More information can be found in the Research Article by M. Temnikova et al.

Anodic Cross-Coupling of Biomass Platform Chemicals to Sustainable Biojet Fuel Precursors

Electrocatalytic conversion of biomass platform chemicals to jet fuel precursors is a promising approach to alleviate the energy crisis caused by the excessive exploitation and consumption of non-renewable fossil fuels. However, an aqueous electrolyte has been rarely studied. In this study, we demonstrate an anodic electrocatalysis route for producing jet fuel precursors from biomass platform chemicals on Ni-based electrocatalysts in an aqueous electrolyte at room temperature and atmosphere pressure. The desired product exhibited high selectivity for the jet fuel precursor (95.4%) and an excellent coulombic efficiency of 210%. A series of in situ characterizations demonstrated that Ni2+ species were the active sites for the coupling process. In addition, the coupling reaction could be achieved by generating radical cations and inhibiting the side reaction. First, the electrochemical process could activate the furfural (FF) molecule and generate radical cations, resulting in an average of 2.0 times chain propagation. The levulinic acid (LA) molecules played a vital role in the coupling reaction. The adsorption strength of LA on Ni3N was higher than that of FF, which could inhibit the side reaction (the oxidation of FF) and achieve high selectivity. Meanwhile, the LA molecules were adsorbed on the Ni3N surface and then disrupted the formation of Ni3+ species, thus favoring the coupling reaction. This work demonstrates an efficient route to produce jet fuel precursors directly from biomass platform chemicals and provides a comprehensive understanding of the anodic coupling process.

Catalytic Hydrogenolysis of Lignin into Phenolics by Internal Hydrogen over Ru Catalyst

AbstractLignin is a by‐product of biorefineries and pulp and paper manufacturers. Lignin is a renewable source of phenolic precursors for fuels and chemicals. Hydrogenolysis of lignin cleaves the abundant β‐O‐4 bonds and releases phenolics. However, selective hydrogenolysis of lignin's β‐O‐4 bonds is challenging because it requires high‐pressure H2. Here we show efficient hydrogenolysis of lignin model compounds and technical lignin by Ru/C catalyst and internal hydrogen. The aliphatic hydroxyl groups (Cα−OH) in lignin enabled Ru‐catalyzed dehydrogenation of internal hydrogen and the formation of reactive keto intermediate, which facilitated the β‐O‐4 cleavage into phenolic monomers. Furthermore, solvents that had a high donor number (Lewis basicity) enhanced the yield of phenolic monomers, equal to 27.9 wt.% from technical lignin. These findings offer a novel approach for biorefineries to design lignin isolation processes and/or solvent systems to maximize phenolic monomers and to control product selectivity/stability.

Highly Selective Conversion of CO2 or CO into Precursors for Kerosene-Based Aviation Fuel via an Aldol–Aromatic Mechanism

The extensive emission of CO2 into the atmosphere due to the burning of fossil fuels has urged many countries to move toward decarbonized energy. Based on the concept of carbon neutrality, the European Union Emissions Trading System implemented the aviation carbon tax (ACT), which stimulated the rapid transformation in aviation fuels. To cope with the ACT and mitigate the CO2 emissions from the aviation industry, here, we present a promising route for the synthesis of precursors such as aromatics, alkyl benzenes, and naphthenes, which account for 40–50 vol % fraction of the kerosene-based aviation fuel, from waste CO2 or biomass-derived syngas. The ultra-high selectivity of single-ring aromatics (precursors for the kerosene-based aviation fuel) with a selective range of carbon chain numbers (C8–C12) was achieved (>80% in hydrocarbons at a reaction temperature of 275 °C) via the catalytic hydrogenation of CO2 or CO over a bifunctional catalyst (nano-sized ZnCr2O4/Sbx-H-ZSM-5). In situ diffuse reflectance infrared Fourier transform spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, gas chromatography–mass spectrometry, and reaction analysis revealed that the product distribution was controlled by thermodynamics and the formation of the aromatics followed an “aldol–aromatic” mechanism. The high selectivity of aromatics at the low reaction temperature (i.e., 275 °C) was attributed to the catalyst topology, the closed carbon chain aromatization reaction, and the presence of highly active oxygenated species in the hydrocarbon pool. For the first time, an asymmetric desorption behavior between the active oxygenate species and aromatic hydrocarbons over the ZnCr2O4/Sbx-H-ZSM-5 catalyst is reported with the help of integrated differential phase contrast scanning transmission electron microscopy, which made the reaction highly selective toward aromatics. This strategy gives a carbon-neutral route for the synthesis of kerosene-based aviation fuel precursors and will reduce the burden of the carbon tax on the aviation industry.