Biomass-derived Chemicals Research Articles

Trace Ru Incorporation Boosted Co2P Nanorods for Superior Water Electrolysis and Substrate-Paired Electrolysis Toward Value-Added Chemicals in Alkaline Medium.

Electro-valorization of biomass-derived chemicals has ensured sustainable production of value-added products, an effective approach for reducing carbon footprint, through renewable energy. Electrochemical oxidation and reduction reactions in aqueous media using H2O as a potential source for active hydrogenated and oxygenated species fulfill the purpose. In this study, Ru─Co2P nanorods are explored as a bifunctional electrocatalyst toward valorization of Organics at basic media. The in-situ electrogenerated Co3+ and Co4+ species act as active oxidants toward product selectivity. An overpotential of 68mV is found for hydrogen evolution reaction (1m NaOH) with Ru─Co2P. Further, used as cathode, Ru─Co2P effectively reduces furfuraldehyde to furfuryl alcohol and p-nitrophenol to p-aminophenol. Ru doping enables ease of formation of active species both for reduction and oxidation, faster charge transfer between catalyst to absorbates. Density Functional Theory calculation establishes Ru incorporation in Co2P surface results in enhanced adsorption of substrates. Ru doping modulates the electronic structure of Co2P which changes the density of states resulting in faster water dissociation and water splitting. To reach 10mAcm-2 current density only 1.6V is required for water electrolysis, whereas 1.4V is enough for substrate-paired electrolysis with simultaneous oxidation of benzyl alcohol and reduction of p-nitro phenol.

Photocatalytic β-O-4 bond cleavage in lignin models and native lignin through CdS integration on titanium oxide photocatalyst under visible light irradiation

Converting lignin, a key sustainable biopolymer, into valuable oxygen-containing compounds is a significant challenge. To address such a challenge, photocatalytic self-transfer hydrogenolysis strategy is employed utilizing a CdS(x%)/TiO2 heterojunction photocatalyst, with minimal CdS loading on TiO2. The CdS(3 %)/TiO2 catalyst, under blue light, dehydrogenates HCα–OH groups, transferring hydrogen to Cβ–O bonds, cleaving β-O-4 ether bonds in lignin model compounds yielding over 95 % phenols and acetophenones. It utilizes glyceryl moieties as a hydrogen source, yielding ∼ 24 % of diverse lignin monomer derivatives from teak lignin. Improved charge separation in the CdS(3 %)/TiO2 catalyst is revealed by electrochemical and spectral analyses and exhibits delayed charge carrier recombination. Scavenging studies confirm a type II charge transfer mechanism and support visible-light-driven lignin fragmentation. The present photocatalytic process offers a promising, cost-effective approach for converting lignin into valuable aromatic compounds, advancing renewable biomass-derived chemicals.

Synergistic effects of La loading on furfural hydrogenation using wrinkled silica-supported Pd catalysts: Role of partially oxidized Pd and base sites

The catalytic hydrogenation of furfural (FF) to tetrahydrofurfuryl alcohol (THFAL) is complicated by competing hydrogenation reactions involving the carbonyl group and furan ring. To address this challenge, we developed Pd/xLa@wrinkled silica (Pd/xLa@KCC) catalysts exhibiting excellent efficiency via the optimization of La/Si molar ratios, improved Pd dispersion, and stabilization of partially oxidized Pd particles (Pdδ+). These catalysts were designed for the selective hydrogenation of FF to THFAL. Pd/0.2La@KCC, characterized by a high level of oxygen defects, good basicity, and abundant Pdδ+ species, achieved complete conversion and 91.2 % THFAL selectivity at 45 °C within 6 h. Pd/0.2La@KCC exhibited a THFAL formation rate of 100.9 mmol/g/h, 10.8 times higher than that of Pd/0.02La@KCC. Improved Pd dispersion increased the available metallic surface area for H2 dissociations, whereas abundant Lewis-base sites and Pdδ+ species served as adsorption sites for the carbonyl group and furan ring, respectively. The catalyst facilitated the activation and conversion of the furan ring and carbonyl group to THFAL owing to the parallel adsorption geometry of FF. This approach highlights the importance of the surface characteristics of the catalyst for achieving exceptional selectivity and efficiency. Our findings provide valuable insights into the development of advanced catalysts exhibiting excellent selectivity for biomass-derived chemicals.

Production of Jet Fuel Range Aromatics by Alkylation of Benzene with Olefins over Bifunctional Ga/ZSM-5 Catalyst.

Aromatic components of C8-C15 are playing indispensable roles in multi-functional properties of jet fuel. Here, we reported the controllable alkylation of benzene with mixed olefins of ethylene and propylene toward C8-C15 aromatic hydrocarbons for jet fuels over the bifunctional Ga/ZSM-5 catalyst. The resultant 2Ga/ZSM-5 exhibited a superior selectivity of 86.4% (yield of 55.5%) to C8-C15 range aromatics, at benzene conversion of 40.3%, ethylene and propylene conversion of 99.5% and 99.2%, respectively. The incorporation of Ga species could effectively weaken the strong acid sites of ZSM-5 and endow 2Ga/ZSM-5 catalyst with appropriate acidity, therefore facilitating the benzene alkylation process and suppressing the undesired hydrogen transfer or aromatization side reactions as well, thus improving the yield of desired C8-C15aromatics for jet fuels. This work provided insight into the development of promising bifunctional catalyst for the oriented transformation of biomass-derived chemicals to aviation fuels.

Degradation effect on oxidation of 5-hydroxymethyl-2-furaldehyde over cobalt-iron electrocatalysts in alkaline condition

Nowadays, the excessive utilization of fossil-based chemicals has caused serious environmental problems, especially due to the negative carbon footprints. Addressing this issue by substituting fossil resources with environmentally friendly biomass is imperative. This study focuses on the electrooxidation of 5-hydroxymethyl-2-furaldehyde (HMF), a biomass-derived chemical, into 2,5-furandicarboxylic acid (FDCA) in alkaline solutions, a crucial feedstock, for the chemical industry. Given the acknowledged instability of HMF in an alkaline environment, this research investigated the kinetic approximation of HMF degradation under varying concentrations of KOH solutions (0.1 M and 1 M KOH) over 12 hours. Then, the electrooxidation of HMF to FDCA over cobalt-iron-based catalysts was investigated. As a result, the FDCA was successfully produced in 0.1 M KOH solution with a remarkable yield of up to 94 %, while a higher concentration (1 M KOH solution) accelerated the electrooxidation process. However, the yield and Faradaic efficiency could be greatly dropped after 12 hours of storing time due to the effects of HMF degradation reactions (Cannizaro and polymerization reactions). Therefore, this degradation phenomenon should be considered on an industrial scale, particularly when HMF may be stored for an extended period before utilization.

Renewable biomass based jet fuel: Aldol condensation of furfural with 3-pentanone over calcium zirconium mixed oxide catalyst

Furfural is a biomass-derived chemical that can be converted into different valuable chemicals using green processes. The current study deals with a highly efficient, robust, and selective solid catalyst for the aldol condensation of furfural and 3-pentanone to synthesize 1-furan-2-yl-2-methylpent-1-en-3-one under environmentally benign conditions. CaZr (different molar ratios of Ca and Zr) mixed oxide (MO) catalysts along with reference CaO and ZrO2 catalysts were prepared by the hydrothermal technique and investigated for the current reaction. Among all, CaZr (1:2) MO catalyst was found to be the best for the conversion of furfural due to its desirable basic strength with good surface area and reusability characteristics. Furfural conversion and 1-furan-2-yl-2-methylpent-1-en-3-one selectivity were found to be 94 % and 98 %, respectively, under optimized reaction conditions. Effect of various reaction parameters was studied carefully to achieve the maximum yield of the required product. Reaction mechanism and kinetics were developed. The reaction aligns with the LHHW mechanism, and the activation energy was determined to be 10.40 kcal/mol.

Preparation of Value-added Chemicals via Chemical Looping Pyrolysis of Corn Straws with Ca-Fe Composite Oxygen Carrier

Biomass chemical looping pyrolysis (BCLPy), which utilizes either reduced or oxidized oxygen carriers for biomass pyrolysis, enables the simultaneous production of high-quality bio-oils and clean syngas. In this study, CLPy of corn straws with a Ca-Fe composite oxygen carrier was investigated to produce value-added chemicals by optimizing both temperature and the mass ratio of oxygen carrier to biomass (OC/B). It has been demonstrated that the reduced Ca-Fe oxygen carrier (Re-OC) promotes hydrocarbon formation and facilitates removal of oxygenated compounds from bio-oils. Under optimal conditions (Re-OC/B = 4:3, T = 650 °C), the relative percentage of benzene, toluene and xylene (BTX) in the bio-oil reaches 27.0 area%, while that of 2-pentenone accounts for 38.0 area% at 550 °C with a Re-OC/B mass ratio of 1:3. The maximum yield based on corn straws approaches 4.7 wt.%. Regarding the oxidized Ca-Fe oxygen carrier (Ox-OC), the relative percentage of 2,3-dihydrobenzofuran (2,3-DHB) reaches a maximum value of 11.6 area% at 600 °C with an Ox-OC/B mass ratio of 2:3. Under catalytic ketonization of Ca2Fe2O5 oxygen carrier, a maximum value of 28.0 area% is achieved with an Ox-OC/B mass ratio of 4:3 at 450 °C. In summary, BCLPy provides a completely new strategy for producing biomass-derived chemicals with added value.

Efficient Glucose Isomerization to Fructose using Photoregenerable MgSnO3 Catalyst with Cooperative Acid-Base Sites.

The isomerization of glucose to fructose plays a crucial role in the food industry and the production of biomass-derived chemicals in biorefineries. However, the catalyst used in this reaction suffers from low selectivity and catalyst deactivation due to carbon or by-product deposition. In this study, MgSnO3 catalyst, synthesized via a facile two-step process involving hydrothermal treatment and calcination, was used for glucose isomerization to fructose. The catalyst demonstrated outstanding catalytic performance, achieving a fructose equilibrium yield of 29.8 % with a selectivity exceeding 90 % under mild conditions owing to its acid-base interaction. Notably, spent catalysts can be regenerated by photoirradiation to remove surface carbon, thereby avoiding the changes in properties and subsequent loss of activity associated with conventional calcination regeneration method. This novel approach eliminates the energy consumption and potential structural aggregation associated with traditional calcination regeneration methods. The acid-base active sites of the catalyst, along with their corresponding catalytic reaction mechanism and photoregeneration mechanism were investigated. This study presents a demonstration of the comprehensive utilization of catalytic material properties, i. e., acid-base and photocatalytic functionalities, for the development of a green and sustainable biomass thermochemical conversion system.

Development of sustainable sugarcane bagasse biorefinery using a greener deep eutectic solvent from hemicellulose-derived acids

Acid-based deep eutectic solvents (ADES) have recently been tested as an emerging technology in biomass deconstruction. In particular, the use of hemicellulose-derived carboxylic acids has attracted great interest as this type of ADES can enable a sustainable closed-loop biorefinery, due to their efficiency and recyclability. Therefore, this study proposed the pretreatment of sugarcane bagasse (SCB) with acetic acid, as a biomass-derived chemical, and choline chloride [ChCl]:AA to perform a complete biomass fractionation to enhance enzymatic digestibility. Thus, this work analyzed the effect of different temperatures and reaction time during pretreatment, studying the impact on biomass composition and digestibility during enzymatic hydrolysis. In addition, the reuse of ADES to produce an environmentally friendly and low-cost SCB biorefinery was explored by studying the physicochemical modifications in polysaccharide-rich material (PRM) and lignin-rich material (LRM) by ATR-FTIR and SEM photography. Furthermore, the ADES content was also characterized by HPLC after each recycling cycle. The results demonstrated efficient polysaccharide conversion, promoting an enrichment in glucan (>60%) and xylan (>20%) content under mild operating conditions (130°C and 90 min) supported by ATR-FTIR and SEM. Furthermore, SCB pretreated under these selected conditions achieved higher digestibility, increasing by 89% for glucan and 73% for xylan, using a simple and competitive process. In contrast, increasing the temperature above 130°C did not improve the enzymatic digestibility of SCB. Thus, ChCl:AA could be recycled and reused. Therefore, this study demonstrated the potential of AA in DES pretreatments as an environmentally friendly and efficient method for the valorization of SCB components.

Synergy of metallic Co and oxygen vacancy sites in Co/Ce-MOF catalysts for efficiently promoting lignin derived phenols and macromolecular lignin hydrodeoxygenation

The enhanced utilization of biomass-derived chemicals for the generation of high value aromatics through an advanced catalytic strategy has captured considerable attention within the realm of eco-friendly manufacturing. This work presented four innovative three-dimensional rod-shaped mesoporous Ce-based MOF materials, which were coupled with a H-donor solvent to facilitate vanillin hydrodeoxygenation and macromolecular lignin. Under the optimized conditions (30 mg CoCe@C catalyst, 2 MPa N2 pressure, 15 mL isopropanol, 190 °C, and 5 h), the CoCe@C catalyst achieved nearly complete conversion of vanillin and demonstrated 87.8 % selectivity in the hydrogen-donor solvent. The characterization findings suggested that the synergy between metallic Co and oxygen vacancy sites enabled the effective activation of CHO group in vanillin, leading to formation of reactive product MMP. In addition, the optimal CoCe@C catalyst could also achieve macromolecular lignin hydrodeoxygenation to obtain high yield of lignin oil products with narrower molecular weight distribution. This study presented a viable approach for the concurrent utilization of lignin derivatives in the generation of high value fuels and chemicals.

Heteropolyacid promoted lignin-MOF derived spherical catalyst for catalytic hydrogen transfer of 5-hydroxymethylfurfural

Catalytic conversion of biomass-derived value-added chemicals was of great significance for the utilization of renewable biomass resources to instead of fossil chemicals. Biomass-derived lignin was regarded as an important support and 5-hydroxymethylfurfural (HMF) was a vital platform chemical derived from cellulose. Herein, a series of lignin-MOF hybrid catalysts were prepared and modified with different heteropolyacids (HPAs), which were then successfully introduced into the selective conversion of HMF to 5-hydroxymethylfurfuryl alcohol (MFA). The effect of different HPA, calcination temperature, etc. were all studied, and all catalysts were well characterized. It was confirmed that silicotungstic acid modified catalyst (Ni3Co-MOF-LS@HSiW) exhibited the best catalytic performance, while the highest conversion of HMF was up to 100%, with the best MFA yield of 86.5%. The finding in this study could provide novel insights for the utilization of lignin and preparation of value-added biomass-derived chemicals.

Reduction of 5-Hydroxymethylfurfural to 2,5-Bis(hydroxymethyl)Furan at High Current Density using a Ga-Doped AgCu:Cationomer Hybrid Electrocatalyst.

Hydrogenation of biomass-derived chemicals is of interest for the production of biofuels and valorized chemicals. Thermochemical processes for biomass reduction typically employ hydrogen as the reductant at elevated temperatures and pressures. Here, the authors investigate the direct electrified reduction of 5-hydroxymethylfurfural (HMF) to a precursor to bio-polymers, 2,5-bis(hydroxymethyl)furan (BHMF). Noting a limited current density in prior reports of this transformation, a hybrid catalyst consisting of ternary metal nanodendrites mixed with a cationic ionomer, the latter purposed to increase local pH and facilitate surface proton diffusion, is investigated. This approach, when implemented using Ga-doped Ag-Cu electrocatalysts designed for p-d orbital hybridization, steered selectivity to BHMF, achieving a faradaic efficiency (FE) of 58% at 100mAcm-2 and a production rate of 1mmolcm-2h-1, the latter a doubling in rate compared to the best prior reports.

Solvation enhanced long-range proton transfer in aqueous phase for glycolaldehyde hydrogenation over Ru/C catalyst.

The catalytic hydrogenation of biomass-derived chemicals is essential in chemical industry due to the growing demand for sustainable and renewable energy sources. In this study, we present a comprehensive theoretical investigation regarding the hydrogenation of glycolaldehyde to ethylene glycol over a Ru/C catalyst by employing density functional theory and abinitio molecular dynamics simulations. With inclusion of explicit solvation, we have demonstrated that the glycolaldehyde hydrogenation is significantly improved due to the fast proton transfer through the hydrogen bond network. The enhanced activity could be attributed to the participation of the solvent water as the hydrogen source and the highly positively charged state of a Ru cluster in an aqueous phase, which are critical for the activation of aldehyde groups and proton-assisted hydrogenation. Overall, our findings provide valuable insights into glycolaldehyde hydrogenation over Ru/C catalysts in the aqueous phase, highlighting the importance of solvation effects in the biomass conversion.

Integration of theory prediction and experimental electrooxidation of glycerol on NiCo2O4 nanosheets

Electrocatalytic refinery of low-value biomass-based glycerol into value-added chemicals formic acid (FA) is an attractive alternative to traditional thermochemical refineries. However, constructing non-precious catalysts with abundant active hydroxyl (OH*) is the main obstacle to the electrocatalytic glycerol oxidation reaction (EGOR). Herein, we combine density functional theory (DFT) and experiments to investigate EGOR over the finely constructed NiCo2O4 nanosheets. DFT results firstly indicate that the NiCo2O4 nanosheets exhibit the highly hydroxylated (311)-OH* surface with the lowest Gibbs free energy, which significantly improves the electrochemical reaction kinetics and can achieve desirable FA yield by adjusting the adsorption energy of the adsorption intermediate. Following the theoretical prediction, ultrathin NiCo2O4 nanosheets (~1.70 nm) are fabricated by a facile electrodeposition method with sufficient OH* on the surface. The charge-transfer resistance of NiCo2O4 nanosheets in EGOR is only 0.94 Ω and the anode power consumption can be reduced by up to 320 mV at 10 mA cm−2, keeping the high glycerol conversion (89%) and FA selectivity (70%) during the 120-h stability test. DFT calculations and experimental tools (e.g., multi-potential step experiments, operational electrochemical impedance spectroscopy) confirm that OH* in-situ generated on the thin nanosheets structure is essential in facilitating charge transfer between catalysts and adsorbed molecules to enhance C–C bond cleavage. This work offers a guideline for the rational design of robust catalysts for the selective upgrading of biomass-derived chemicals.

Ultrafine Ru nanoparticles deposited on lignin-derived nitrogen-doped carbon nanolayer for the efficient conversion of levulinic acid to γ-valerolactone

Carbon-supported Ru-based catalysts have shown great potential in the hydrodeoxygenation of biomass-derived chemicals but still suffer from the uneven/unstable metal loading owing to the weak affinity between the metal and the carbon-based support. Herein, novel ultrafine Ru nanoparticles supported on lignin-derived nitrogen-doped carbon layers (Ru/LNC) were prepared through a facile pyrolysis of lignin-Ru complex mixed with melamine and further subjected to the hydrodeoxygenation of levulinic acid (LA) into γ-valerolactone (GVL) using formic acid (FA) as the H-donor. The formation of lignin-Ru complexes and abundant N-anchoring sites collaboratively improve the dispersion of metals, thus forming the ultrafine Ru nanoparticles (∼3 nm). Meanwhile, the base site generated by nitrogen -doping promotes the adsorption of acidic reactants (FA and LA) to improve the catalytic performance. Therefore, Ru/LNC catalyst exhibited outstanding catalytic performance (99.5 % of LA conversion and 98.4 % of GVL yield), which was significantly higher than Ru/LC (without N doping) and Ru/C (fabricated through convention impregnation method). Owing to the strong interaction of N species and Ru nanoparticles, Ru/LNC also exhibited improved reusability. Consequently, this work proposes a novel route to fabricate ultrafine Ru nanoparticles embedded on lignin-derived nitrogen-doping carbon nanolayer and further demonstrates its superior applicability in LA hydrodeoxygenation.

CNSL-based plasticizers, a promising sustainable alternative to phthalates, a review.

With growing environmental concerns and the depletion of petrochemical resources, biomass-derived chemicals have garnered significant attention. Biomass-derived plasticizers have been widely studied as alternatives to toxic petroleum-based plasticizers. However, many...

Electrochemical Production of Methyltetrahydrofuran, a Biofuel for Diesel Engines

Methyltetrahydrofuran (MTHF) can be derived from non-edible biomass and used to replace diesel fuel. MTHF can be produced through the hydrogenation of furfural using hydrogen sourced from methane. Electrochemical hydrogenation (ECH) offers a method to source hydrogen from water, while bypassing the challenges associated with H2 handling and storage. Thus, if furfural were converted into MTHF through ECH, clean liquid fuels could be formed for internal combustion engines. The challenge is that ECH has not been proven to produce MTHF in meaningful yields due to solubility and thermodynamic constraints. We report here the successful electrochemically-driven hydrogenation of furfural to MTHF using a membrane reactor. This membrane reactor is able to produce MTHF production because the site of water electrolysis is separated from the site of hydrogenation so that hydrogenation can occur in organic media at high current densities. We show how the membrane reactor favors MTHF production at a selectivity of >75% at 200 mA/cm2, compared to conventional ECH using a single cell that operates at lower selectivities (<35%) and current densities (50 mA/cm2). We mapped out the reaction pathways to show that MTHF is produced from the deoxygenation of a furfuryl alcohol intermediate, a pathway that does not occur in single-cell ECH. This work shows the power of using the membrane reactor for producing liquid fuel alternative from a biomass-derived chemical, water, and electricity.

Conversion of Biomass-Derived Molecules into Alkyl Levulinates Using Heterogeneous Catalysts

Alkyl levulinates are promising and versatile biomass-derived chemicals, which are utilized as fuel additives, flavoring agents, fragrances, solvents, and precursors for synthesizing valuable γ-valerolactone. A method for synthesizing alkyl levulinates involves the esterification of levulinic acid with the corresponding alkyl alcohols in the presence of solid acid catalysts that have abundant Brønsted acid sites. Alkyl levulinates can also be synthesized from other biomass-derived molecules such as furfuryl alcohol and furfural via alcoholysis and one-pot conversion, respectively. Thus far, various heterogeneous catalysts have been developed for the conversion of the biomass-derived molecules (levulinic acid, furfuryl alcohol, and furfural) into alkyl levulinates. To obtain the target products in high yields, numerous strategies have been employed including increasing Brønsted acidity, dispersing and incorporating Brønsted acid sites, inducing the formation of mesopores, and inducing a synergistic effect of metal–Brønsted acid sites that are present on a catalyst surface. Here, we summarily reviewed the performances of the heterogeneous catalysts in the conversions, describing the design and development of the heterogeneous catalysts that ensured the excellent yield of alkyl levulinates.

Current Status and Challenges for Metal-Organic-Framework-Assisted Conversion of Biomass into Value-Added Chemicals.

Owing to the abundance of availability, low cost, and environmental-friendliness, biomass waste could serve as a prospective renewable source for value-added chemicals. Nevertheless, biomass conversion into chemicals is quite challenging due to the heterogeneous nature of biomass waste. Biomass-derived chemicals are appealing sustainable solutions that can reduce the dependency on existing petroleum-based production. Metal-organic frameworks (MOFs)-based catalysts and their composite materials have attracted considerable amounts of interest in biomass conversion applications recently because of their interesting physical and chemical characteristics. Due to their tunability, the catalytic activity and selectivity of MOF-based catalyst/composite materials can be tailored by functionalizing them with a variety of functional groups to enhance biomass conversion efficiency. This review focuses on the catalytic transformation of lignocellulosic biomass into value-added chemicals by employing MOF-based catalyst/composite materials. The main focus is given to the production of the platform chemicals HMF and Furfural from the corresponding (hemi)cellulosic biomass, due to their versatility as intermediates for the production of various biobased chemicals and fuels. The effects of different experimental parameters on the conversion of biomass by MOF-based catalysts are also included. Finally, current challenges and perspectives of biomass conversion into chemicals by MOF-based catalysts are highlighted.

Pd-Catalyzed Activation of Carbon-Carbon Bonds in Hydroxymethylfurfural Derivatives.

Palladium-catalyzed activation of C-C bonds in organic molecules is a powerful tool for the synthesis of value-added compounds. 5-Hydroxymethylfurfural (HMF) derivatives are a promising class of biomass-derived chemicals that have received considerable attention due to their potential applications in the synthesis of biologically active molecules and materials. However, the selective activation of unstrained C-C bonds is a challenging task, mainly due to their relatively high bond dissociation energies. Herein, we report a palladium-catalyzed method for the efficient C-C bond activation of HMF derivatives, enabling their arylation with iodobenzenes. Mechanistic studies, including reaction-profile analysis, competition experiments and head-space IR spectroscopy suggest a decarboxylative mechanism.