Search Results (36)

This study presents an integrated catalytic system enabling the quantitative production of 2,5-diethoxymethylfuran from HMF through a hybrid sequence that combines Ru-PNP-catalyzed hydrogenation with heterogeneous acid-catalyzed etherification in ethanol. The approach provides complete selectivity under mild conditions and demonstrates the compatibility of homogeneous hydrogenation catalysts with solid acid co-catalysts in a single process environment. In addition, we report the first example of homogeneously catalyzed hydrogenative valorization of HMF employing a co-catalytic, potentially recyclable acid additive. This strategy expands the scope of HMF upgrading pathways and highlights the potential of hybrid catalytic systems for the efficient synthesis of stable, energy-dense furan derivatives relevant to biofuel and biobased chemical applications. Full article

Cellulose has received significant attention, given its high demand for the transition to sustainable fuels and renewable energy, addressing the environmental challenges of fossil fuels. Fast pyrolysis is a process that can transform cellulose into bio-oil. Although the bio-oils produced contain considerable amounts of oxygen and water, they are highly corrosive and highly viscous, which limits their utility as biofuels. Pyrolysis bio-oils require upgrading to remove oxygen and corrosive components, thereby enhancing their stability for use as biofuels and their environmental sustainability. This study investigates the catalytic pyrolysis of cellulose without a catalyst and with Ga/HZSM-5 catalysts with various gallium loadings (0.3, 3 and 9 wt%) and bulk Ga₂O₃ catalysts using pyrolysis/gas chromatography–mass spectrometry (Py/GC-MS). The catalytic influence of different gallium loadings on HZSM-5 in cellulose pyrolysis reactions is discussed using a range of characterisation techniques, including ICP, XRD, N₂ porosimetry, DRIFTS, and TPRS. The main production of oxygenated compounds (furan, sugar, ketone and phenol) and hydrocarbon products, including total aromatic and monocyclic and polycyclic aromatics, as well as benzene, toluene, xylene (BTX) and naphthalene compounds, using a family of Ga-doped HZSM-5 catalysts for cellulose pyrolysis is investigated for making sustainable cellulose-derived fuel. Ga(3)/HZSM-5 formed the highest amount of aromatics, displaying that aromatic yield depends on the Brønsted-to-Lewis acid balance (2.3 ratio) and total acidity (1.03 mmol·g⁻¹), rather than on gallium loading alone. Full article

With the advancement of new synthetic techniques, 5-Methyl-2-ethylfuran (5-MEF) has emerged as a promising renewable biofuel. In this study, the potential energy surfaces for the unimolecular dissociation reaction, H-addition reaction, and H-abstraction reaction of 5-MEF were mapped at the CBS-QB3 level. The temperature- and pressure-dependent rate constants for these reactions on the potential energy surfaces were determined by solving the master equation, using both transition state theory and Rice–Ramsperger–Kassel–Marcus theory. The results showed that the dissociation reaction of the C(6) site on the branched chain of 5-MEF has the largest rate constant and is the main decomposition pathway, while the dissociation reaction of the H atom on the furan ring has a lower rate constant and is not the main reaction pathway. In addition, the dissociation of H atoms on the branched chain and intramolecular H-transfer reactions also have high-rate constants and play an important role in the decomposition of 5-MEF. H-addition reactions mainly occur at the C(2) and C(5) sites, and the generation of the corresponding products through β-breakage becomes the main reaction pathway. With the increase in temperature, the H-addition reaction at the C(2) site gradually changes to a substitution reaction, dominating the formation of C₂H₅ and 2-methylfuran. Full article

Hydrothermal carbonization (HTC) is an efficient method for converting lignocellulosic biomass into biofuels. However, traditional Brønsted acid-catalyzed HTC processes face challenges such as high costs and limited catalytic efficiency. In this study, the catalytic carbonization mechanism was investigated within the temperature range of 180–220 °C by analyzing the evolution of functional groups in hydrochar under lanthanide (III)-catalyzed and non-catalyzed conditions. The results indicate that compared to acid catalysis, lanthanide (III) exhibits superior catalytic performance during the low-temperature HTC of cellulose. At 200 °C, lanthanide (III) accelerates the conversion of cellulose into char microparticles, while at 220 °C, it promotes the complete hydrolysis of cellulose into char microparticles enriched with furan structures. Characterization analyses revealed that lanthanide (III) enhances the formation of HMF (5-hydroxymethylfurfural), suppresses its conversion to LA (levulinic acid), promotes the polymerization of HMF into char microparticles, and indirectly accelerates the hydrolysis of cellulose into oligosaccharides. Full article

Brewer’s spent grains (BSG) are a by-product of the beer industry and can be used to produce biofuels. In this case, the objective of this study was to obtain reducing sugars from this biomass by subcritical water hydrolysis in a semi-continuous mode after steam explosion. Temperatures of 120–180 °C, reaction times of 1–5 min, and pressures of 15–25 MPa were used for the steam explosion without CO₂. Moistures of 10–50% (w/v), temperatures of 120–180 °C, reaction times of 1–5 min, and pressures of 15–25 MPa were used for the steam explosion with CO₂. Subcritical water hydrolysis of solid-exploded material was developed at 210 °C, 15 MPa, a solid/feed ratio of 16 g/g, and a flow rate of 20 mL/min. The characterization of BSG, reducing sugar yields, kinetic profiles, the composition of monosaccharides and furanic moieties, and the characterization of remaining solid by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) were performed. For steam explosion with CO₂, the significant variables were the temperature and moisture, and the optimized conditions were moisture of 50% (w/v), 120 °C, pretreatment for 1 min, and 15 MPa, with a reducing sugars yield of 18.41 ± 1.02 g/100 g BSG. For steam explosion without CO₂, the significant variables were the time and temperature, and the optimized conditions were 120 °C, pretreatment for 1 min, and 15 MPa, with a reducing sugars yield of 17.05 ± 0.48 g/100 g BSG. The process was successful because the steam explosion ruptured the lignocellulosic matrix, and the subsequent process of subcritical water hydrolysis could dissociate the polymers into low-chain saccharides. Full article

Furfural, an important biobased compound, can be synthesized through the chemocatalytic conversion of D-xylose and hemicelluloses from lignocellulose. It has widespread applications in the production of valuable furans, additives, resins, rubbers, synthetic fibers, polymers, plastics, biofuels, and pharmaceuticals. By using barley hulls (BHs) as biobased support, a heterogeneous biochar Sn-NUS-BH catalyst was created to transform corncob into furfural in cyclopentyl methyl ether–H₂O. Sn-NUS-BH had a fibrous structure with voids, a large comparative area, and a large pore volume, which resulted in more catalytic active sites. Through the characterization of the physical and chemical properties of Sn-NUS-BH, it was observed that the Sn-NUS-BH had tin dioxide (Lewis acid sites) and a sulfonic acid group (Brønsted acid sites). This chemocatalyst had good thermostability. At 170 °C for 20 min, Sn-NUS-BH (3.6 wt%) was applied to transform 75 g/L of corncob with ZnCl₂ (50 mM) to generate furfural (80.5% yield) in cyclopentyl methyl ether–H₂O (2:1, v/v). This sustainable catalytic process shows great promise in the transformation of lignocellulose to furfural using biochar-based chemical catalysts. Full article

As fossil-based resource depletion intensifies and the use of lignocellulosic biomass gains more and more momentum for the development of biorefineries, the production of furans has received a great deal of attention considering their outstanding synthetic possibilities. The production of 5-hydroxymethylfurfural (HMF) is quite established in the recent scientific literature, with a large number of studies having been published in the last few years. Lately, there has been a growing interest in the synthesis of 5-chloromethylfurfural (CMF) as a novel building block of similar molecular structure to that of HMF. CMF has some advantages, such as its production taking place at milder reaction conditions, a lower polarity that enables easier separation with the aid of organic media, and the presence of chlorine as a better leaving group in synthesis. Precisely the latter aspect has given rise to several interesting products to be obtained therefrom, including 2,5-dimethylfuran, 2,5-furandicarboxylic acid, and 5-methylfurfural, to name a few. This work covers the most relevant aspects related to the production of CMF and an array of synthetic possibilities. Through varied catalysts and reaction conditions, value-added products can be obtained from this chemical, thus highlighting the advances in the production and use of this chemical in recent years. Full article

Biomass-derived furanics play a pivotal role in chemical industries, with 2-methyltetrahydrofuran (2-MTHF), a hydrogenated product of levulinic acid (LA), being particularly significant. 2-MTHF finds valuable applications in the fuel, polymer, and chemical sectors, serving as a key component in P-series biofuel and acknowledged as a renewable solvent for various chemical processes. Numerous research groups have explored catalytic systems to efficiently and selectively convert LA to 2-MTHF, using diverse metal-supported catalysts in different solvents under batch or continuous process conditions. This comprehensive review delves into the impact of metal-supported catalysts, encompassing co-metals and co-catalysts, on the synthesis of 2-MTHF from LA. The article also elucidates the influence of different reaction parameters, such as temperature, type and quantity of hydrogen source, and time. Furthermore, the review provides insights into reaction mechanisms for all documented catalytic systems. Full article

Energy demands keep increasing in this modern world as the world population increases, which leads to a reduction in fossil fuels. To resolve these challenges, Pennisetum purpureum, an invasive grass in Brunei Darussalam, was examined as the feedstock for renewable energy through a catalytic pyrolysis process. The activated carbon was applied as the catalyst for a simple and economical solution. The catalytic pyrolysis was executed at 500 °C (the temperature for the highest biofuel yield) for both reactors to produce the highest amount of upgraded biofuels. The biochar produced from the non-catalytic and catalytic pyrolysis processes showed a consistent yield due to stable operating conditions, from which the activated carbon was generated and used as the catalyst in this work. A significant amount of improvement was found in the production of biofuels, especially bio-oil. It was found that for catalysts, the number of phenolic, alcohol, furans, and ketones was increased by reducing the amount of acidic, aldehyde, miscellaneous oxygenated, and nitrogenous composites in bio-oils. The highest amount of phenolic compounds was produced due to a number of functional groups (-C=O and -OH) in activated carbon. The regenerated activated carbons also showed promising outcomes as catalysts for upgrading the bio-oils. The overall performance of synthesized and regenerated activated carbon as a catalyst in catalytic pyrolysis was highly promising for improving the quality and stability of bio-oil. Full article

This work reports a straightforward and high-yielding synthesis of alkyl levulinates (ALs), a class of promising biofuel, renewable solvent, and chemical feedstock of renewable origin. ALs were prepared by the acid-catalyzed esterification of levulinic acid (LA) and by the alcoholysis of carbohydrate-derived chemical platforms, such as furfuryl alcohol (FAL) and α-angelica lactone (α-AGL). Phosphotungstic acid (PTA) was chosen as the solid acid catalyst for the transformation, which was heterogenized on humin-derived activated carbon (HAC) for superior recyclability. Using HAC as catalyst support expands the scope of valorizing humin, a complex furanic resin produced inevitably as a side product (often considered waste) during the acid-catalyzed hydrolysis/dehydration of sugars and polymeric carbohydrates. Under optimized conditions (150 °C, 7 h, 25 wt.% of 20%PTA/HAC-600 catalyst), ethyl levulinate (EL) was obtained in an 85% isolated yield starting from FAL. Using the general synthetic protocol, EL was isolated in 88% and 84% yields from LA and α-AGL, respectively. The 20%PTA/HAC-600 catalyst was successfully recovered from the reaction mixture and recycled for five cycles. A marginal loss in the yield of ALs was observed in consecutive catalytic cycles due to partial leaching of PTA from the HAC support. Full article

Levoglucosan is an anhydrosugar from biomass that has important applications as a platform for obtaining many value-added derivatives with high demand in the chemical industry and bioproducts by fermentation, including biofuels, among others. Thus, the experimental strategy was to intensify the levoglucosan production in the condensable fraction (bio-oil) from pyrolysis gases using different biomass pretreatments before fast pyrolysis according to the following conditions: (a) biomass washing with 10% acetic acid; (b) biomass washing with 0.1% HNO₃, followed by impregnation with 0.1% H₂SO₄; and (c) biomass impregnation with 0.1% H₂SO₄. The pyrolysis was carried out in a pyroprobe reactor, coupled to GC/MS to verify the progress of the chemicals formed at 400, 500, and 600 °C. Although levoglucosan was the main target, the programs showed more than 200 pyrolytic compounds of which more than 40 were identified, including organic acids, ketones, aldehydes, furans, and phenols. Then, principal component analysis (PCA) allowed for the discrimination of the simultaneous effect of biomass acid treatment and pyrolysis temperature on the formation of the pyrolytic products. All treated biomasses with acids resulted in a levoglucosan yield increase, but the best result was achieved with acetic acid at 500 °C which resulted from 7-fold higher levoglucosan production with changes in the profiles by-products formed concerning untreated biomass. This result was attributed to the alkali and alkaline earth metals reduction and partial removal of lignin content and extractives by acid washing, increasing the cellulose and hemicellulose relative content in the treated biomass. This hypothesis was also confirmed by scanning electron microscope (SEM) and Fourier transform infrared (FTIR) qualitative analysis. Thus, the results achieved in this work show the potential of this biomass for levoglucosan production and other pyrolytic products, thereby being able to mitigate the environmental impact of this agricultural residue and contribute to the development of the coffee agro-industrial chain and the production of bioenergy from lignocellulosic biomass. Full article

This study proposes a simple correlation for approximating hydrogen solubility in biomaterials as a function of pressure and temperature. The pre-exponential term of the proposed model linearly relates to the pressure, whereas the exponential term is merely a function of temperature. The differential evolution (DE) optimization algorithm helps adjust three unknown coefficients of the correlation. The proposed model estimates 134 literature data points for the hydrogen solubility in biomaterials with an excellent absolute average relative deviation (AARD) of 3.02% and a coefficient of determination (R) of 0.99815. Comparing analysis justifies that the developed correlation has higher accuracy than the multilayer perceptron artificial neural network (MLP-ANN) with the same number of adjustable parameters. Comparing analysis justifies that the Arrhenius-type correlation not only needs lower computational effort, it also has higher accuracy than the PR (Peng-Robinson), PC-SAFT (perturbed-chain statistical associating fluid theory), and SRK (Soave-Redlich-Kwong) equations of state. Modeling results show that hydrogen solubility in the studied biomaterials increases with increasing temperature and pressure. Furthermore, furan and furfuryl alcohol show the maximum and minimum hydrogen absorption capacities, respectively. Such a correlation helps in understanding the biochemical–hydrogen phase equilibria which are necessary to design, optimize, and control biofuel production plants. Full article

Being a lignocellulose-rich biomass, pineapple leaves waste (PL) could be a potential raw material for the production of biofuel, biochemicals, and other value-added products. The main aim of this study was to investigate the potential of pineapple leaves in the sustainable production of bioethanol via stepwise saccharification and fermentation. For this purpose, PL was subjected to hydrothermal pretreatment in a high-pressure reactor at 150 °C for 20 min without any catalyst, resulting in a maximum reducing sugar yield of 38.1 g/L in the liquid fraction after solid-liquid separation of the pretreated hydrolysate. Inhibitors (phenolics, furans) and oligomers production were also monitored during the pretreatment in the liquid fraction of pretreated PL. Enzymatic hydrolysis (EH) of both pretreated biomass slurry and cellulose-rich solid fraction maintained at a solid loading (dry basis) of 5% wt. was performed at 50 °C and 150 rpm using commercial cellulase at an enzyme dose of 10 FPU/gds. EH resulted in a glucose yield of 13.7 and 18.4 g/L from pretreated slurry and solid fractions, respectively. Fermentation of the sugar syrup obtained by EH of pretreated slurry and the solid fraction was performed at 30 °C for 72 h using Saccharomyces cerevisiae WLP300, resulting in significant ethanol production with more than 91% fermentation efficiency. This study reveals the potential of pineapple leaves waste for biorefinery application, and the role of inhibitors in the overall efficiency of the process when using whole biomass slurry as a substrate. Full article

Background: Bioenergy attracts much attention due to the global demand for renewable and sustainable energy resources. Waste biomass feedstocks—date pits, coffee waste, and cow dung—require efficient and environmentally friendly waste-management technologies such as pyrolysis. Fast pyrolysis occurs at fast heating rates (10–100 °C/s), generates high bio-oil yields, and is the most widely used process for biofuel generation. The aim of the study is to compare the effect of pyrolysis between single, binary, and ternary feeds on thermal degradation behavior and bio-oil composition. Methods: Thermogravimetric analysis (TGA) was conducted at 30 °C/min from room temperature to 850 °C to understand the thermal degradation behavior of the biomasses. A Pyroprobe^® reactor—a micro-scale pyrolyzer—was used to conduct the fast pyrolysis at 500 °C with a heating rate of 10 °C/s, and the volatile contents were quantified using a gas chromatograph–mass spectrometer (GC/MS). Results: The (TGA) showed three main stages of decomposition following dehydration, devolatilization, and char degradation for the different single and multiple feeds. According to the identified compounds, the bio-oil components are broadly identified as aldehydes, amines, aliphatic, aromatics, alcohols, furans, ketones, and acids. The three single-biomass pyrolysis products have four compounds in common, acetic acid and ketone groups (acetic acid, 2-propanone, 1-hydroxy-, benzyl methyl ketone, and 1,2-cyclopentanedione). Conclusion: The bio-oil generated from the feeds comprises great potential for volatiles, diesel, and gasoline production with carbon atoms ranging from C2–C33. Future studies should focus on understanding the effect of procedural parameters, including blending ratio, temperature, and heating rates, on bio-oil composition. Additional molecular techniques should be employed to understand biomass components’ reaction mechanisms to produce useful bio-oil products. Full article

As a versatile and valuable intermediate, furfuryl alcohol (FOL) has been widely used in manufacturing resins, vitamin C, perfumes, lubricants, plasticizers, fuel additives, biofuels, and other furan-based chemicals. This work developed an efficient hybrid strategy for the valorization of lignocellulosic biomass to FOL. Corncob (75 g/L) was catalyzed with heterogenous catalyst Sn-SSXR (2 wt%) to generate FAL (65.4% yield) in a deep eutectic solvent ChCl:LA–water system (30:70, v/v; 180 °C) after 15 min. Subsequently, the obtained FAL liquor containing FAL and formate could be biologically reduced to FOL by recombinant E. coli CF containing aldehyde reductase and formate dehydrogenase at pH 6.5 and 35 °C, achieving the FOL productivity of 0.66 g FOL/(g xylan in corncob). The formed formate could be used as a cosubstrate for the bioreduction of FAL into FOL. In addition, other biomasses (e.g., sugarcane bagasse and rice straw) could be converted into FOL at a high yield. Overall, this hybrid strategy that combines chemocatalysis and biocatalysis can be utilized to efficiently valorize lignocellulosic materials into valuable biofurans. Full article