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The use of chemical and energy intensive delignification processes in industrial pulping generates cellulosic fibres that are hydrophilic, hygroscopic and functionally restricted to paper and cardboard applications. Here, we propose a bio-based alternative to chemical pulping utilising herbivores to harvest and grind lignocellulosic materials followed by natural fungal growth to delignify and hybridise them to generate hierarchical composite papers with altered, water-repelling surface properties. These papers comprise cellulose and fungal biopolymers produced by cultivation of T. versicolor and P. ostreatus on elephant manure. Papers with considerably more hydrophobic surfaces were obtained at glucosamine contents as low as 0.1 wt%. Paper tensile strengths and elastic moduli were improved with longer fungal growth periods, spanning several weeks, resulting in comprehensive interfacing of cellulose microfibrils through tough nanoscale fungal chitin-β-glucan networks within the papers. Papers produced from lignocellulosic material colonised with P. ostreatus for 16 weeks exhibited the highest tensile strengths and more hydrophobic surfaces than T. versicolor. Hybridisation of lignocellulose with fungal biopolymers resulting in improved surface and mechanical properties highlights the extended opportunities of fungal delignification bioprocessing and demonstrates the considerable potential of the fungal biorefinery as an economical, and as of yet underexploited technology. [ABSTRACT FROM AUTHOR]

The document is a contents list for the journal "Green Chemistry," published by The Royal Society of Chemistry. It highlights the articles and research papers included in the issue, covering topics such as sustainable water treatment, lignocellulose pretreatment, and biomass valorization. The journal aims to promote cutting-edge research for a greener and more sustainable future. [Extracted from the article]

This study shows a functional deep eutectic solvent (DES) employing choline chloride (ChCl) and glyoxylic acid (GA) for lignocellulose fractionation. This DES exhibited a higher pretreatment efficiency (92.15%) than that composed of ChCl and lactic acid (10.36%). Molecular dynamic (MD) simulations indicated that the ChCl : GA DES showed a higher total binding energy (ΔE) with lignin than the ChCl : LA DES, resulting in a higher dissolution of lignin. GA prevented lignin condensation during pretreatment. The stabilized lignin containing 69.39% β-O-4 linkages can be used for phenolic monomer production with a bio-oil yield of 59.60% and lignin-based sunscreen preparation with a SPF of 58.46. The cellulose residues with a mild pretreatment severity exhibited a high enzymatic saccharification yield of 91.99%. Meanwhile, an esterification reaction occurred between cellulose and GA during pretreatment. The inhibition of enzymatic hydrolysis and microbial growth enables the use of functional cellulose to produce antibacterial paper. Furthermore, 96.80% of the DES could be easily recycled and reused for biorefinery purposes. [ABSTRACT FROM AUTHOR]

Sustainable production of 1,4-pentanediol (1,4-PDO) from biomass is of great importance because 1,4-PDO is a monomer of degradable polyesters and plastics. This paper reviews the conversion of biomass-derived levulinic acid (LA) and furfural as well as their derivatives alkyl levulinate, γ-valerolactone (GVL) and furfuryl alcohol (FAL) into 1,4-PDO. MoOx or ReOx modified noble metal catalysts and non-noble metal catalysts with core–shell and alloy structures show a high 1,4-PDO yield and stability in LA hydrogenation under severe hydrothermal conditions. The conversion of furfural to 1,4-PDO involves the initial C＝O bond hydrogenation to form FAL, the consecutive acid-catalyzed ring-opening and the final hydrogenation. Therefore, it needs a bifunctional catalyst composed of metallic species and acid sites to improve the 1,4-PDO yield. Efforts are made here to highlight the employed catalysts, structure–performance relationship, reaction pathway and reaction mechanism in detail. The current challenges for large-scale applications of conversion of LA and furfural to 1,4-PDO have been proposed, including process development, catalyst cost, solvent and active site distribution. We believe that this review will provide new opportunities and expand the options for the production of 1,4-PDO via biorefining processes. [ABSTRACT FROM AUTHOR]

Pure subcritical water autohydrolysis is an economical and green biorefinery method and potentially applicable technology. Elucidating and regulating the energy input effects on the structural dissociation and chemical depolymerization of lignocellulosic biomass will progress the industrialization of pure subcritical water autohydrolysis biorefineries. In this work, a method for determining the degree of tissue dissociation was invented. Combined with the analysis of the microstructure, ultrastructure, chemical composition, and aggregation state, this paper reveals the process and mechanism of the P-factor effect as an energy input measurement on the bio-structural dissociation and chemical depolymerization during naked oat stem autohydrolysis. A method of using the P-factor to regulate the biostructural dissociation and chemical depolymerization was developed. For the first time, a critical point for the autohydrolysis of naked oat stem in pure subcritical water between 170–210 °C was found to be at a P-factor = 233, around which an essential change in biostructural dissociation and chemical depolymerization occurred. The findings indicate that the control of naked oat-stem tissue and cell dissociation, ultrastructure, and chemical depolymerization can be accomplished using the P-factor as an energy input measurement for autohydrolysis. The revealed mechanism and method created in this study enable the stepwise separation of gramineae tissues, cells, and major chemical components, enabling a full-composition multi-purpose biorefinery of lignocellulose. [ABSTRACT FROM AUTHOR]

Pretreatment facilitates cost-effective operations on lignocellulosic biomass ranging from densification to deconstruction and bioproduct development. However, determining molecular-level mechanisms behind pretreatment and their effects has remained elusive. Here, we combine computational simulation and experiment to investigate the effects on wheat straw agricultural residue densification of an emerging pretreatment solvent, namely, a deep eutectic solvent (DES) consisting of choline chloride (ChCl) and oxalic acid (OA). Ab initio molecular dynamics indicates that dissociation of lignin from cellulose in lignin–carbohydrate complexes, which does not occur to a significant extent in aqueous solution, is favorable in the DES and occurs via cleavage of the guaiacyl : xylose ether bond linkage by OA. The ensuing hemicellulose removal exposes lignin to the DES which, molecular dynamics simulation indicates, leads to lignin expansion. The resulting changes in wheat straw fiber structure, lignin distribution, and functional group modifications upon DES treatment by scanning electron and fluorescence microscopy along with Fourier-transform infrared spectroscopy. The molecular expansion of lignin enhances inter-particle binding in wheat straw, leading to denser structures under pelletization. The resulting high mechanical stability and combustion properties make the wheat straw a suitable precursor of high-quality densified solids (e.g., solid biofuel). Overall, we shed light on the molecular-level mechanisms involved in DES pretreatment for biomass densification, demonstrated here in the development of a solid biofuel. The approach here illuminates the rational design from first chemical principles of methods to convert lignocellulosic resources into advanced materials. [ABSTRACT FROM AUTHOR]

Cellulose in particular and phytomass in general are at the heart of our food system. They are also a central energy vector and a vital source of materials. In this article, a multiscale approach to the complex issue of lignocellulose sustainability is developed. Global thermodynamic concepts help to place current biomass exploitation in a global energetic context. In particular, the notion of entropy appears pivotal to understand energy and material fluxes at the scale of the planet and the limits of biomass production. Entropy is, however, best described at the microscopic scale, despite its large-scale consequences. Recent advances in entropy-driven colloid assembly parallel nature's choices and lignocellulose assembly at the nanometric scale. The functional concept of exergy is then developed and a few examples of its concrete use in photosynthesis and biorefinery research are given. In a subsequent part, an evaluation of the relative importance of biomass is performed with respect to non-renewable materials. This discussion helps to explain the interdependence of resources, including ores and fossil fuels. This interdependence has important consequences for current and future biomass uses. Some of these dependences are then quantitatively discussed using life cycle analysis (LCA) results from the literature. These results are of importance to different technological fields such as paper, biobased insulation, construction wood, information and communication technologies, and biobased textiles. A conclusion is then drawn that exposes the research tracks that are the most likely to be sustainable, including self-assembly, exergetically favourable options and low tech solutions. [ABSTRACT FROM AUTHOR]

When attempting to obtain light-color lignin from lignocellulosic biomass or industrial lignin, the available options based on chemical or morphological modification suffer from low yield, high cost, and lack of availability at the required scales. In this study, we adopted a polyhydric-alcohol-based deep eutectic solvent (PA-DES) to directly extract light-color lignin from natural biomass, which is even whiter than native cellulolytic enzyme lignin (CEL). The isolated lignin possessed a high recovery yield (97.36%), regular micro-spherical morphology, enriched β-ether linkage of 58/100Ar, low phenolic hydroxyl content of 1.25 mmol g−1, minimal carbonyl content of 0.70 mmol g−1, and less condensed structures, thus yielding a lower content of chromophores. This lignin showed excellent sunscreen effects, which could enhance the SPF of a commercial sunscreen from 15 to 40 with only 5 wt% addition. This study can provide essential guidance for the scale-up production of light-color lignin and obtaining near-complete digestible cellulose for further saccharification. [ABSTRACT FROM AUTHOR]

Derived from lignocellulosic biomass, sustainable hard carbon has emerged as a promising low-cost anode material for sodium-ion batteries (SIBs). However, the intricate formation process of the hard carbon microstructure remains unclear. This study investigates the structural differences and pyrolysis behaviors of pine lignin and its graded variants obtained through a lignin molecular sieving engineering strategy. Moreover, it delves into the relationship between the microstructure of lignin-derived hard carbon and its sodium-ion storage characteristics. Pristine pine lignin, along with ethanol-isolated lignin, acetone-isolated lignin, and residual lignin, serves as a precursor for synthesizing hard carbon materials. Quantitative analysis via31P NMR spectroscopy reveals the highest content of polar functional groups in ethanol-isolated lignin. Interestingly, hard carbon derived from ethanol-isolated lignin exhibits the smallest closed pore volume, leading to the lowest plateau capacity of sodium-ion storage. Conversely, hard carbon derived from acetone-dissolved lignin displays the highest plateau capacity owing to its largest closed pore volume formed in the carbonization process. The origin of open and closed pore structures of hard carbons is thoroughly analyzed. [ABSTRACT FROM AUTHOR]

Enhancing the production of biochemicals from lignocellulosic biomass is one potential way to decrease society's dependence on fossil fuels. Aromatic compounds obtained from plant biomass can be used as substrates for microbial production of dicarboxylic acids such as 2-pyrone-4,6-dicarboxylic acid (PDC) and cis,cis-muconic acid, which are building blocks for the manufacturing of polymer-based fibers and materials. In this study, we used an engineered strain of the bacterium Novosphingobium aromaticivorans to investigate how to increase PDC productivity in flow-through bioreactors receiving aqueous solutions of aromatics. At the best operational conditions tested, we achieved stable PDC production rates of 0.77 gPDC L−1 h−1 with p-hydroxybenzoic acid, 1.93 gPDC L−1 h−1 with syringic acid, and 1.53 gPDC L−1 h−1 with the products from alkaline pretreated poplar biomass. PDC titers in these reactors ranged from 7.7 to 15 g L−1 (42 to 80 mM) and were limited by aromatic solubility in the case of syringic acid, or by accumulation of protocatechuic acid from p-hydroxybenzoic acid when high aromatic loading rates were used. The use of high aromatic loading rates, hollow-fiber membranes to concentrate the microbial cells, and NH4OH for pH control were factors that contributed to this study achieving the highest PDC productivities reported to date. Overall, our findings demonstrate strategies that can be used to increase bioreactor productivity when aromatic substrates are delivered in aqueous form. These findings may also provide useful insight for production of other biochemicals from aromatic streams using N. aromaticivorans or other microbial chassis. [ABSTRACT FROM AUTHOR]

Lignin, a crucial component of lignocellulosic biomass, holds immense promise for advancing biorefineries and producing sustainable energy alternatives. This study engineered a CN/rGO/BMO (2 : 1) heterojunction photocatalyst with varying Pd NP loading to selectively target the hydrogenolysis of challenging C–O ether bonds in lignin model compounds. Specific focus was on β-O-4, α-O-4, and the formidable 4-O-5 linkages. The 4-O-5 linkage, due to its high dissociation energy, poses a significant challenge. Electrochemical and spectral analyses unveiled improvements in charge separation, leading to delayed recombination of charge carriers in the heterojunction photocatalyst. Decorating the heterojunction with Pd NPs exhibited an elevated work function and a low Fermi energy level, facilitating the accommodation of photogenerated electrons and enabling efficient H2 dissociation. Such enhancement facilitated the cleavage of all three linkages, including the resistant 4-O-5 bonds under ambient conditions. The photocatalyst exhibited effective cleavage, yielding aromatic (toluene, phenol, ethylbenzene) and aliphatic (cyclohexane, ethylcyclohexane) products. Selectivity modulation was achieved by adjusting the time, hydrogen pressure, and Pd loading. Furthermore, this photocatalytic approach successfully transformed simulated lignin bio-oil containing all three linkages into valuable monomers. The alcoholic solvents efficiently harnessed photogenerated holes and prevented electron–hole recombination. The photocatalyst also demonstrated the capability to produce monomers from the native lignin extracted from teak wood sawdust. Emphasizing the focus on the reaction pathway and mechanism, scavenging studies and analyses were conducted, including UPS and VBXPS, to establish the Z-scheme charge transfer mechanism within the heterojunction. These findings provide a sustainable and efficient pathway for lignin valorisation in biorefineries, significantly contributing to the advancement of green fuels and aligning with the principles of green chemistry. [ABSTRACT FROM AUTHOR]

Recently, the ambient drying method for the preparation of xerogels has attracted great attention due to its low cost and high drying efficiency. However, the strong capillary forces existing during ambient drying cause severe shrinkage or even collapse of the aerogels (called xerogels). Although chemical crosslinking or displacement of water by organic solvents have been tried to solve the problem, extensive usage of chemicals and time-consuming displacement processes seem to be environmentally unfriendly and complex. Herein, we reported a green and efficient method for the preparation of a lignocellulosic xerogel. The xerogel was fabricated by alkali freezing of unbleached eucalyptus fibers followed by water washing and ambient drying. The alkali freezing promoted fiber swelling and enhanced the hydrogen bonds among the fibers, resulting in the gelation of lignocellulosic fibers. In particular, the residual lignin in the fibers reduced the capillary force during the drying process. The resulting lignocellulosic xerogel achieved a low shrinkage rate (27.50%), low density (0.039 g cm−3 ), high porosity (97.57%), and excellent mechanical strength (782.23 kPa) as well as environmental stability, and low thermal conductivity (44.76 mW m−1 K−1 ). Similarly structured xerogels could be generated using recycled NaOH solution. This technique was suitable for production using various kinds of plant fibers, which shows its great scalable production prospects. [ABSTRACT FROM AUTHOR]

Lignocellulose biorefining has great potential to replace the use of petrochemical resources in the production of fuels and chemicals. However, the full use of lignocellulose, which is depolymerized to yield mainly glucose, xylose, and lignin-derived phenolics, remains challenging. Here, we developed a glucose–xylose–phenolics (GXP) system to fully use lignocellulose for the production of L-tyrosine and its analogues in minimal medium. First, we engineered an Escherichia coli–Escherichia coli consortium carrying a CRISPR/dCas9 interference system to simultaneously use glucose and xylose to support cell growth and produce pyruvate, obtaining 34.3 g L−1 pyruvate with a yield of 0.68 g g−1 sugar. Then, we introduced tyrosine phenol lyase and other biocatalytic enzymes into this consortium to generate the GXP system, which could convert pyruvate and lignin-derived phenolics to L-tyrosine and its analogues. Using this GXP system, 20.8 g L−1L-tyrosine was produced from 12.5 g L−1 phenol with a yield of 86.4%. Using the hydrolysate of the raw material sorghum pith, 0.94 g L−1L-tyrosine was produced from 0.96 g L−1p-coumaric acid with a yield of 88.7%, and 8.1 g L−1 pyruvate remained, corresponding to an overall yield of 0.163 g product g−1 sorghum pith. The development of this GXP system illustrates a strategy for fully utilizing lignocellulosic biomass for the synthesis of value-added chemicals. [ABSTRACT FROM AUTHOR]

The fabrication of lignocellulose-based hydrogels typically involves complex modification or dissolution processes using a single component of lignocellulose. However, these processes often have a significant environmental impact, posing challenges to achieving green production of these hydrogels. In this study, we present a non-dissolving strategy to convert whole components of corn stover directly into hydrogel. The central step in this strategy is to expose more functional groups in the corn stover through steam explosion. The exposure of functional groups allowed the steam-exploded corn stover to strengthen the mechanical properties of poly(vinyl alcohol) (PVA) hydrogel by forming more hydrogen bonds with PVA molecules. The tensile strength of the prepared lignocellulose-based hydrogel reached 329.75 kPa, which was 432.69% higher compared to the pure PVA hydrogel. Furthermore, this hydrogel exhibited the advantageous properties of lignin, such as antioxidant and UV resistance capabilities, and was shown to be useful as a sand-fixing agent for large-scale applications. Finally, we verified the universal applicability of the non-solubilizing strategy by preparing similarly shaped hydrogel products from wheat bran and poplar wood flour as well. In summary, our non-dissolving strategy provides a simpler and more cost-effective method than the intricate process of creating lignocellulose-based hydrogels. This simplification helps convert abundant lignocellulosic materials into valuable products. [ABSTRACT FROM AUTHOR]

Sweet cherry pomace waste (CPW) obtained after juice production still contains high amounts of dietary fiber and added value compounds such as polyphenols. For this reason, it can be employed as renewable feedstock to produce novel commodities, bioactive compounds and bio-functional materials. In this study, a sustainable biorefinery approach has been developed combining the use of natural deep eutectic solvents (NADESs) for the recovery of polyphenolic compounds and bio-based ionic liquids (bio-ILs) for the treatment and conversion of the remaining lignocellulosic residue into an ionogel. The extraction efficiency and selectivity of different classes of (NA)DESs were evaluated varying both the hydrogen bond acceptor, HBA (choline chloride (ChCl), betaine (Bet) and L -proline (Pro)) and the hydrogen bond donor, HBD (carboxylic acids and polyols). The extracted phenolic compounds were qualitatively and quantitatively analyzed by UHPLC-HR-ESI-MS leading to the identification of more than 25 compounds, classifiable into four main subclasses (phenolic acids, flavonoid glycosides, flavonoid aglycones, and anthocyanins). The majority of ChCl-based DESs improved the total phenol extraction compared to classical solvents (up to twice). ChCl : ethylene glycol 1 : 2 was identified as the best performing system in terms of total phenolic content (total phenol 759 ± 85 μg g−1 of dried CPW) and was employed as the extraction medium for further optimization of the operative conditions and recycling study. The solvent was quantitatively recovered for three cycles with retention of the extraction efficiency towards all the identified subclasses of phenols. Finally, cholinium arginate (ChArg) allowed for obtaining cellulose enriched material (35 wt% of dried biomass) that was subsequently dissolved at 2 wt% in cholinium levulinate (ChLev) to prepare a weak physical ionogel, a functional biomaterial potentially useful in medical and pharmaceutical sectors. [ABSTRACT FROM AUTHOR]

Deep eutectic solvents (DESs) and ionic liquids (ILs) are potential solvents for lignocellulosic biomass fractionation. In this study, the rice straw pretreatment efficiency of four cholinium-based solvents (DESs and ILs) prepared from the same sources (lactic acid and lysine) were comparatively investigated at 110 °C for 4 h. The lignin removal rate correlated well with the saccharification efficiency of the pulps. Quantum chemical (QC) calculations and molecular dynamics (MD) simulations focused on the microscopic structure and non-covalent interactions of the solvents and lignin model molecules (guaiacylglycerol-β-guaiacyl ether, GG) were carried out, and the results indicate that anions of the solvent systems play a leading role (through strong hydrogen bonds or electrostatic interactions) in establishing interactions with GG, supported by cations (via van der Waals interactions). There were clear positive relationships between the total interaction energies (IEs) and lignin removal, cellulose digestibility and glucose yields. In particular, [Ch][Lys] with a low self-interaction energy is able to free some active sites to form strong hydrogen bonds and electrostatic interactions with lignin, thus resulting in lignin dissolution and excellent delignification. For cholinium cations, an ideal partner system provides low self-IEs for solvent molecules and strong IEs between solvents and lignin, which are determined by the type and number of functional groups and the alkyl chain length of the partner components. This work provides ideas about tailoring suitable partner systems for cholinium cations to build solvents for efficient biomass deconstruction. [ABSTRACT FROM AUTHOR]

In the context of promoting a circular bioeconomy, the development of green and efficient lignocellulosic biomass pretreatment technologies so as to realize high value-added biomass utilization is of intense interest. We demonstrated the potential of the bio-based green solvent dimethyl isosorbide (DMI) for the fractionation of Eucalyptus biomass with excellent performance. Here, to investigate the mechanisms involved in biomass fractionation, microimaging and microspectroscopic techniques were employed together with molecular dynamics (MD) simulation and COSMO-RS quantum chemical calculations to derive multiscale information. Both the microstructure and regional chemistry of the cell wall vary significantly with the volume ratio of DMI/H2O. The strongest effects were found at DMI/H2O = 9 : 1 and showed visible cell wall tearing cracks and cell wall deformation and collapse as well as the lowest values of cell wall thickness and circularity. From the MD simulations, lignin exhibits collapsed-like structure in pure H2O with low solvent accessibility surface area (SASA) and radius of gyration (Rg). In contrast, lignin in DMI/H2O shows extended structure with high SASA and solvent interactions dominated by van der Waals forces, with maximal contact in the 9 : 1 (v/v) system. Further, the COSMO-RS calculated sigma (σ-) potential suggests the intermolecular interactions in DMI and DMI/H2O co-solvent are weak, leading to stronger interaction with lignin and correspondingly higher lignin dissolution. The radial distribution functions and σ-potential all show that again DMI/H2O at 9 : 1 is an optimal volume ratio for high lignin dissolution. This study provides a solvent-ratio dependent mechanism for the action of polar aprotic solvents in the deconstruction of biomass. [ABSTRACT FROM AUTHOR]

Renewable hemicellulose with a unique structure exhibits a wide range of potential applications. However, it has been a formidable challenge to isolate hemicellulose with an intact structure from lignocellulosic materials. In this study, LiBr·3H2O (LBTH) was used as a green solvent for the effective fractionation of hemicellulose from bleached hardwood kraft pulp (BHKP) under mild conditions (25–85 °C). It was found that hemicellulose in BHKP can be dissolved in LBTH with ease and high selectivity owing to the breaking of hydrogen bonds between hemicellulose and cellulose, and the dissolved hemicellulose can be regenerated with a high degree of polymerization (DP) in the range of 240–264 using ethanol precipitation. The highest removal rate of hemicellulose from BHKP was as high as 95.2%, and the corresponding yield of pure hemicellulose reached 84.3%. Moreover, simultaneously obtained undissolved cellulose pulp through LBTH treatment had a high content of α-cellulose (96.7%), high DP (880), and trace levels of Fe (2 ppm), which met the standard requirement for dissolving pulp for the production of lyocell. In addition, LBTH can be easily recycled to guarantee a green and sustainable process. This work provides a new approach for highly selective fractionation of hemicellulose and cellulose from commercial BHKP based on an efficient and environmentally friendly LBTH treatment, which could be very promising for better valorization of hemicellulose and cellulose in many advanced applications. [ABSTRACT FROM AUTHOR]

Glucose oxidase (GOx) catalyzes the oxidation of D -glucose to D -glucono-1,5-lactone and has a wide range of applications in various industries. However, the strict substrate specificity of GOx hampers its application in the conversion of other abundant sugars such as D -xylose. In this study, the substrate preference of GOx from Aspergillus niger (AnGOx) was engineered using a semi-rational design approach. The mutant T110V/F414L exhibited a 5.7-fold increase in D -xylose oxidation activity compared to that of the wild-type enzyme, which was attributed to its enhanced affinity for the substrate. Molecular dynamics simulations indicated that the T110V and F414L mutations may mitigate the non-productive binding of D -xylose at the entrance of the substrate-binding pocket, and therefore, are beneficial for providing access of its C1 hydroxyl group to the catalytic residues. Moreover, the mutant simultaneously oxidized D -xylose and D -glucose in the corncob hydrolysate to the corresponding aldonic acids when coupled with catalase. These findings provide new insights into substrate recognition by GOx and offer a new method for the utilization of D -xylose from lignocellulosic feedstocks. [ABSTRACT FROM AUTHOR]

Deep eutectic solvents (DESs) are widely used as recyclable green solvents for the separation of lignin from lignocellulosic biomass. However, the poor permeability of DES solution limits the green advancement of separation systems. In addition, lignin fragment molecules are susceptible to repolymerization reactions during separation, resulting in reduced lignin reactivity. In this study, a DES consisting of choline chloride (ChCl) as a hydrogen acceptor, 5-sulfosalicylic acid (5Saa) as a hydrogen donor, and a certain amount of γ-valerolactone (GVL) as an additive was designed. The system not only efficiently fractionated lignin from poplar (71.35%), but also selectively retained almost complete cellulose (retention 92.87%) under the optimal fractionation (ChCl/5Saa/GVL molar ratio 1/4/15, temperature 120 °C, time 3.0 h). Pre-crushing processing of raw materials was avoided as the new DES solution has stronger permeability compared to the previous DES solution. Selective deconstruction of lignocellulose was achieved due to a strong hydrogen network structure. The lignin fragments were effectively dissolved. The results showed that the stability of the carbo-positive active intermediates was enhanced by ChCl–5Saa/GVL. Lignin with a low molecular weight (2305 g mol−1), high purity (98.77%) and high total phenolic hydroxyl content (6.92 mmol g−1) was obtained. Homogeneous lignin nanoparticles (LNPs) were prepared with an average particle size of 23 nm. LNPs had high dispersion stability and excellent UV shielding properties. The green advancement of the new DES has been significantly improved and the efficient fractionation of high-value lignin was realized. [ABSTRACT FROM AUTHOR]

High-density fuel additives are important for heavy transportation. Production of high-density fuel additives from renewable resources has been receiving increasing attention in recent years. Despite the progress in the depolymerization of lignin, cellulose, and hemicelluloses, there are limited studies on integrating lignin and carbohydrates to make value-added products. Here we design a route to synthesize high-density fuel additives with lignin-derived monophenolics and carbohydrate-derived furanics. We performed Brønsted base-catalyzed C-C coupling of phenolics and furanics followed by hydrodeoxygenation catalyzed by a synthesized Ir-ReOx/SiO2 catalyst. Under optimized reaction conditions, the coupling product of phenolics and furanics, bicyclic furyl phenyl precursors, reached a yield of over 90%, and was further hydrodeoxygenated to bicyclohexyl alkanes with a yield of over 98%. The current twostep strategy demonstrates high-selectivity of preparing high-density hydrocarbon fuels from lignocelluloses and provides a possible way to utilize all components of lignocellulosic biomass in an integrated upgrading pathway. [ABSTRACT FROM AUTHOR]

Biomass-derived solvents have been proposed as a novel pathway in biorefining for the realization of biofuels and bioproducts derived from lignocellulosic biomass. Cyrene derived from cellulose has recently been shown to have a high potential as a green organic solvent for pretreating poplar biomass. However, due to its high dynamic viscosity nature, high Cyrene concentration could cause negative effects on the sugar release of the pretreated biomass as well as driving up the operational cost of the lignin recovery. In this study, we combine experimental and computational approaches to examine the impact of Cyrene pretreatment with reduced Cyrene concentration under mild conditions on switchgrass lignin. Our experimental studies indicated correlation between pretreatment condition and recovery and structure modification of lignin. Switchgrass lignin extracted by Cyrene pretreatment possessed high preservation of β-O-4 ether inter-unit linkage, which could provide versatility in the integration of downstream lignin valorization into the modern biorefinery industries. Molecular modeling examining the solvation of switchgrass lignin polymer and the disaggregation of low-molecular weight lignin aggregates under pretreatment conditions indicated that a preferential interaction exists between Cyrene and lignin, which likely drives lignin release, and that the disruption of inter-lignin contacts can be modulated as a non-monotonic function of Cyrene : water ratio. Further, while Cyrene–lignin interactions permit the solubilization of lignin, simulations with proxy reactive-species reveal that changes to the diffusion of these reactive proxies and their localization near linkage sites under Cyrene conditions may inhibit chemical processes. The results indicated that loss of pretreatment efficacy caused by low Cyrene concentration could be compensated by prolonged pretreatment time and high catalyst dosage. [ABSTRACT FROM AUTHOR]

Extraction of native-like lignin from lignocellulose is crucial for maximizing the value of all three major components of biomass. In this study, molecular dynamics was employed to reveal the essence of lignin condensation during the pretreatment of biomass with a promising acidic hydrotropic solution (AHS) at the molecular level. Diols were discovered to effectively suppress the excessive acidity of p-toluenesulfonic acid (pTsOH) in AHS while maintaining its solubilizing effect below a minimal hydrotropic concentration (MHC). The experimental results confirmed that the combined use of 1,4-butanediol and pTsOH can extract native-like lignin under mild conditions. The retention of lignin's β-O-4 linkages can exceed 90%, and the lignin extraction rate was over 80%. The obtained lignin can enhance the efficacy of chemical sunscreens, doubling the sun protection factor (SPF). Simultaneously, the residual cellulose was readily hydrolyzed into glucose by cellulase. This strategy demonstrates excellent adaptability to various biomass sources, including herbaceous species, hardwoods, and highly recalcitrant softwoods. The work lays the theoretical foundation for the precise control of biomass component separation using AHS, contributing to the development of mild and efficient component separation technologies in the future. [ABSTRACT FROM AUTHOR]

Fast-growing plants with a high carbon fixation capability are promising candidates for mitigating climate change and serving as a renewable resource to replace fossil fuels. Nonetheless, their short lifespan and extensive use lead to the significant accumulation of underutilized waste. While conventional thermal energy extraction remains dominant in biomass utilization, the lack of appropriate carbon capture and storage techniques results in unavoidable CO2 emissions. In contrast, the fine reforming of lignocellulosic biomass offers the potential to reduce CO2 emissions. However, the polymeric, complex and rigid structure of lignocellulosic biomass poses challenges, necessitating energy-intensive pretreatment, where the balance between wood particle size reduction (and thus energy consumption) and pretreatment duration is often overlooked. Herein, we developed a facile energy-saving microwave-hydrothermal method to advance the utilization of fast-growing Paulownia. The optimized sugars (xylose and glucose) after pretreatment can be further converted to formate via a hybrid electrolysis process with the cogeneration of green hydrogen. Both xylose and glucose can be readily converted to formate with high yield and selectivity. This process can be directly powered by PV panel without the safety concerns of hydrogen crossover because oxygen evolution is greatly suppressed. This solar-driven hybrid electrolysis of pretreated Paulownia suggests a pathway to cogenerate green chemicals and green fuels from fast-growing woods while also storing energy from renewable sources in chemical bonds. Overall, this novel synthesis process for green chemicals contributes to the decarbonization efforts and sustainable development initiatives. [ABSTRACT FROM AUTHOR]

It is of great technical interest but still challenging to develop a cost-effective and eco-friendly method to extract high-aspect-ratio elementary nanofibrils with native-state microstructure from recalcitrant lignocellulosic biomass because established chemical/biological/mechanical approaches inevitably give rise to the breakage of cellulose chains during the nanofibrillation of lignocellulose. Nature has designed hierarchical and heterogeneous lignocellulose structures, among which hemicellulose significantly affects interfibrillar interactions due to its unique molecular structure and micro-distribution pattern. Inspired by this fact, we amplify the hemicellulose stimulation effect on nanofibrillation using an on-demand regulated ionic liquid/water cosolvent and dissociate ultrahigh aspect ratio (2213) elementary fibrils (diameter = 4.7 nm) comprising approaching native-state structural carbohydrates from mildly delignified lignocellulose fibers (i.e. holocellulose) by a low-energy blender. We elucidated the mechanism for the exceptional disassembly behavior of holocellulose fibers: the high-level swelling of the amorphous and negatively charged hemicellulose phase weakens fibril–fibril interactions. The high-aspect-ratio morphology, well-preserved cellulose molecular structure, and hemicellulose-rich surface chemistry of the as-prepared nanofibrils significantly affect their self-assembly behavior and contribute to the extraordinary mechanical and optical performances of the corresponding nanopaper that conventional cellulose nano-papers/composites retain unsurpassed, e.g., overcome general conflicts between strength (310 MPa) and toughness (53 MJ m−3) and between transparency (86%) and haze (77%). This work provides a scale-up, ecologically and economically efficient lignocellulose nanostructure-engineered strategy for manufacturing high-performance structural nanomaterials towards a high-tech and carbon-neutral future. [ABSTRACT FROM AUTHOR]

Olefins are important feedstocks in the production of fuels and many useful chemicals. Herein, cobalt molybdate (CoMoO4) was first synthesized by an environmentally friendly evaporation method and it exhibited excellent catalytic performance for the production of olefins by the selective hydrodeoxygenation (HDO) of ketones that can be derived from lignocellulose. On the basis of the characterization results, the excellent catalytic performance of CoMoO4 was attributed to its larger specific surface area, better pore structure, higher oxygen vacancy (or Mo5+ species) concentration, higher acid strength and higher concentration of acid sites. Under the optimized reaction conditions, 4-heptanone was almost completely converted to heptene, and a high carbon yield of heptene (96%) was achieved over a CoMoO4 catalyst with a Co/Mo atomic ratio of 0.8 (denoted as CoMoO4-0.8). The CoMoO4 catalyst is also active for the selective HDO of other lignocellulosic ketones (such as acetone, butanone, 2-pentanone, 3-pentanone, cyclopentanone, cyclohexanone, 5-nonanone and acetophenone) to their corresponding olefins. [ABSTRACT FROM AUTHOR]

The simultaneous upcycling of all components in lignocellulosic biomass and the greenhouse gas CO2 presents an attractive opportunity to synthesise sustainable and valuable chemicals. However, this approach is challenging to realise due to the difficulty of implementing a solution process to convert a robust and complex solid (lignocellulose) together with a barely soluble and stable gas (CO2). Herein, we present the complete oxidative valorisation of lignocellulose coupled to the reduction of low concentration CO2 through a three-stage fractionation–photocatalysis–electrolysis process. Lignocellulose from white birch wood was first pre-treated using an acidic solution to generate predominantly cellulosic- and lignin-based fractions. The solid cellulosic-based fraction was solubilised using cellulase (a cellulose depolymerising enzyme), followed by photocatalytic oxidation to formate with concomitant reduction of CO2 to syngas (a gas mixture of CO and H2) using a phosphonate-containing cobalt(II) bis(terpyridine) catalyst immobilised onto TiO2 nanoparticles. Photocatalysis generated 27.9 ± 2.0 μmolCO gTiO2−1 (TONCO = 2.8 ± 0.2; 16% CO selectivity) and 147.7 ± 12.0 μmolformate gTiO2−1 after 24 h solar light irradiation under 20 vol% CO2 in N2. The soluble lignin-based fraction was oxidised in an electrolyser to the value-added chemicals vanillin (0.62 g kglignin−1) and syringaldehyde (1.65 g kglignin−1) at the anode, while diluted CO2 (20 vol%) was converted to CO (20.5 ± 0.2 μmolCO cm−2 in 4 h) at a Co(II) porphyrin catalyst modified cathode (TONCO = 707 ± 7; 78% CO selectivity) at an applied voltage of −3 V. We thus demonstrate the complete valorisation of solid and a gaseous waste stream in a liquid phase process by combining fractioning, photo- and electrocatalysis using molecular hybrid nanomaterials assembled from earth abundant elements. [ABSTRACT FROM AUTHOR]

Condensation, dark color and low extraction yield of lignin have hindered the full valorization of biomass during lignocellulosic fractionation. Herein, we introduce a novel biomass fractionation concept that addresses the issue of lignin's spatial confinement. Building upon this concept, we have devised an environmentally friendly and straightforward strategy. This approach involves a combination of selective carboxylation at the Cγ-OH position using citric acid and etherification at the Cα-OH position using butanol. The objective is to mitigate the spatial confinement of lignin and stabilize its active intermediates for lignin extraction. Consequently, up to 91.4 ± 0.2% lignin with a light color can be separated from the recalcitrant softwoods, as a UV blocker to improve the performance of sunscreen cream. The cellulosic residue can be enzymatically digested to glucose with a yield of 80%. The initiated biomass fractionation theory and strategy in this study provide a new concept for the isolation of lignin and full valorization of lignocellulose, promoting the development of a sustainable economy. [ABSTRACT FROM AUTHOR]

Fast pyrolysis of lignocellulosic biomass is a promising approach for producing biofuels and renewable chemicals, but the resultant bio-oil quality and diverse product distributions limit its widespread adaptation. Concurrently, the accumulation of waste plastics in the environment, particularly polyolefin thermoplastics, is becoming a growing threat. Co-pyrolysis of biomass with hydrogen-rich thermoplastics has shown promise for producing high-quality bio-oils, presenting an attractive solution to waste management. However, a molecular-level understanding of the synergy of the two components in the molten phase during co-pyrolysis is still lacking. In this work, we report the discovery of catalytic and inhibitory effects on cellulose fast pyrolysis caused by noncovalent interactions (NCIs) induced by molten plastics. Our microreactor experiments demonstrated that selectivity toward cellulose-derived anhydrosugars, small oxygenates, or furans increased due to the presence of polyketone, polyethylene glycol, or polystyrene, respectively, which are three thermoplastics with distinct functional groups. Density functional theory calculations reveal that key cellulose pyrolysis pathways leading to major products are catalyzed or inhibited due to perturbations of transition state geometries and partial charges caused by the NCIs induced by plastic functional groups. This discovery offers insights and opportunities for tuning cellulose fast pyrolysis via NCIs using a new family of unconventional molten plastic catalysts or inhibitors. [ABSTRACT FROM AUTHOR]

The conventional fractionation of lignocellulose into cellulose, hemicellulose, and lignin was generally carried out at high temperatures and under highly acidic conditions owing to the rigid matrix of lignocellulose and crystallinity of cellulose, causing the degradation of carbohydrates and condensation of lignin, thus hindering their value-added utilization. In this study, a stepwise fractionation method was proposed in which microwave-assisted fractionation of hemicellulose under mild conditions contributed to 81.9% of xylose yield; then, the cellulose part solid was rapidly dissolved in LiBr molten salt hydrate (LiBr-MSH) solution, followed by a filtration process to isolate lignin solid. It was found that the removal of hemicellulose provided more pores for the next dissolution of cellulose, and LiBr-MSH caused the cleavage of the hydrogen bonds of cellulose. Consequently, the cellulose part solid was rapidly dissolved in LiBr-MSH. The results showed that under the optimal fractionation conditions, 78.0% yield of glucan oligomers and 89.7% purity of noncondensed lignin were obtained from cellulose fractionation and filtration, respectively. A high β-O-4 bond content close to 87.3% of the theoretical maximum yield was detected in the obtained lignin, indicating that most β-O-4 bond structure of lignin was well preserved. Additionally, the isolated lignin can be selectively depolymerized into aromatic monomers with a high yield of 20.4%, which is 74.2% of the theoretical maximum yield. [ABSTRACT FROM AUTHOR]

Deep eutectic solvents (DESs) are intriguing for biomass fractionation, but high DES dosage and low biomass loading make them challenging to be used in industry. In this study, a DES was integrated into a novel pretreatment technology, namely "Densifying Lignocellulosic biomass with Chemicals followed by Autoclave (DLCA)", to realize lignocellulose fractionation and valorization with low DES dosage and high fractionation efficiency. Remarkably, a total DES dosage of 2 g g−1 biomass, which is substantially low compared to traditional DES pretreatments, achieved a high delignification ratio of 75% with over 95% cellulose preserved at 50% solid loading. Moreover, DLCA(DES)-CS exhibited superior bioconversion efficiency even at high solid loadings, with the maximum total fermentable sugar concentration exceeding 300 g L−1 and the ethanol concentration as high as 110 g L−1. Comprehensive characterization methods such as SEM, XRD, FTIR and Simons' staining were used to disclose the properties of cellulose-rich solids, and the chemical structure of the extracted lignin was characterized by GPC and 2D-HSQC NMR spectroscopy, revealing that DLCA(DES) pretreatment not only ensured complete exposure of cellulose, but also remarkably protected the native structures of lignin. Without recondensation, lignin extracted by DLCA(DES) preserved more than 98% of native β-O-4 linkages. In brief, this study demonstrates great potential for lignocellulose valorization initiated by DLCA(DES) pretreatment, including polysaccharide conversion to bioethanol and selective lignin depolymerization to aromatic monomers. [ABSTRACT FROM AUTHOR]

The development of novel catalysts to regulate product selectivity and insight into the mechanism of lignin hydrogenolysis are important for the comprehensive utilization of lignocellulose. Herein, we present a non-precious bimetallic catalyst Ni5Fe5/Al2O3 with improved catalytic performance relative to commercial Pd/C and Ni10/Al2O3 for hydrogenolysis of woody sawdust. In particular, the selectivity of propylguaiacol and propylsyringol is 79.1%. We developed kinetic experimental studies on β-O-4 model compounds and directly monitored the coniferyl alcohol or sinapyl alcohol intermediates in the reaction system for the first time. This directly demonstrates the lignin hydrolysis reaction pathway with simultaneous breakage of Cα-OH and Cβ-O. In the catalytic system, the reason for the difference in selectivity between Ni5Fe5/Al2O3 and other catalysts is their different hydrogenation pathways for intermediates coniferyl alcohol or sinapyl alcohol. Our work provides both an efficient catalyst and insight into understanding and regulating the mechanism of lignin hydrogenolysis. [ABSTRACT FROM AUTHOR]

When we look for a poster child of green chemistry 'in action', we do not need to look further than the deconstruction of lignocellulose using ionic liquids (IL) to valorize this renewable resource into useful chemicals. However, there is a caveat: successful development of new chemistries cannot be achieved without systems-based design tools that consider performance in conjunction with potential toxicity. Here, we show that a combination of computational approaches, based on quantum mechanics (QM) calculations and Monte Carlo (MC) simulations, can be leveraged to construct a useful framework for screening existing and designing new ILs capable of safe and selective dissolution of lignocellulosic biomass. With the overwhelming number of IL cation–anion combinations, in silico methods are uniquely suited for this challenge so long as they retain mechanistic relevance to the underlying processes. Our computational approach ensures this criterion by relying on well-correlated linear models of interaction energetics between IL and key biomass building blocks. Functional considerations are supplemented with frontier molecular orbital calculations to determine safety toward aquatic species based on previously established and broadly validated guidelines. [ABSTRACT FROM AUTHOR]

Dilute acid (DA) pretreatment of biomass generates multiple inhibitory compounds within the pretreated hydrolysates. These compounds subsequently contribute to the formation of pseudo-lignin on the surface of the substrate, consequently impeding the efficiency of enzymatic digestibility. To detoxify the DA pretreated hydrolysates, post-incubation with non-catalytic proteins (amaranth protein, AP; soy protein, SP; bovine serum albumin, BSA) was performed in the present study. The enzymatic digestibility of DA-pretreated substrates was increased from 40.0% (without non-catalytic proteins) to 64.9, 53.8, and 56.4%, respectively, in the presence of AP (50 mg g−1), SP (65 mg g−1), and BSA (50 mg g−1). The post-incubation of pretreated substrates with non-catalytic proteins led to high hydrophobicity, contact angle, and accessibility, likely due to less formation of pseudo-lignin. Furthermore, gas chromatography/mass spectrometry analysis revealed that AP, SP, and BSA could lower the inhibitor concentrations in the pretreated hydrolysates by 39–100%, 5–100%, and 3–100%, respectively. The detoxification of the pretreated hydrolysates by AP demonstrated superior effectiveness compared to SP and BSA. To assess the affinity between inhibitors and non-catalytic proteins, surface plasmon resonance analysis was conducted, revealing the following affinity rates: AP (18.65 nM) > SP (17.04 nM) > BSA (16.87 nM). Additionally, molecular docking analysis revealed numerous molecular binding sites (i.e., hydrogen, polar, acidic, basic, and greasy contacts) with strong binding affinity ranging from −36.17 to −76.98 kcal mol−1 between the inhibitors and the amino acids of AP. Thus, this study highlights the potential application of AP as a cost-effective strategy for achieving a viable biorefinery. Also, the findings provide valuable insights that can be utilized to advance the development of (hemi)cellulases that exhibit enhanced resistance to lignin and inhibitors. [ABSTRACT FROM AUTHOR]

Various kinds of functional amines have been well synthesized by the reductive amination of carbonyl compounds for high-value pharmaceuticals, but they often suffer from complicated processes and low efficiency. In this study, we developed a facile strategy to achieve product diversity using iron-based nanoparticles, whose catalytic selectivity can be particularly controlled via specific combinations of active metals and carbonaceous matrixes in a simple way; over these catalysts, the main products completely switched from primary amines (>91.2%) to secondary imines (>92.3%) in a one-pot process, in accordance with the observed changes in chemical states (Fe0 to FexOy), particle size (9.3 to 63.2 nm), surface acidity (42.4 to 195.7 μmol g−1), and porosity (388.5 to 14.4 m2 g−1). By further analyzing the differences in reaction routes, the dehydration of nucleophilic amines with excess aldehydes was found to be the crucial step, accelerating the chemical equilibrium turned towards secondary imines. In addition, a wide range of substrates (>15 examples) were well tolerated by the prepared catalysts resulting in good to excellent yields (67.7–96.3%), and the catalytic stability was proven to be standard satisfactorily even after reusing up to five times, which was superior to commercial catalysts with noble or transition metals. More surprisingly, the magnetic properties exhibited by the iron cores allowed easy separation from aqueous systems. Overall, this strategy provides an applicable approach for the preparation of simple but highly efficient catalysts for switchable amination, which fills the knowledge gap on catalytic selectivity and exerts a positive impact on the industrial application. [ABSTRACT FROM AUTHOR]

DLC pretreatment is a novel and efficient pretreatment method for lignocellulosic biomass, but its mechanism of action has not been illustrated yet. In this study, a systematic investigation was conducted to find that the synergy of acidic chemical and mechanical actions during DLC pretreatment played an important role to ensure excellent performance. Mechanical actions likely exposed the internal polysaccharides of biomass by disrupting the cell wall structure, and the exposed polysaccharides reacted with concentrated acid until they were partially deconstructed, thereby significantly reducing the severity of subsequent dilute acid treatment. This synergism increased the accessible breakpoints of crystalline cellulose to cellulase by reducing the cellulose crystallinity and polymerization degree, as well as by digesting amorphous cellulose. Additionally, the large removal (about 60%) of hemicellulose increased biomass porosity. The native lignin structure was well preserved without the generation of pseudo-lignin and large amounts of toxic degradation products. These properties contribute to the high sugar recovery (97.2%), great digestibility (83.4% total yield of monosaccharides), and outstanding fermentability of DLC biomass; these results are not achievable for traditional dilute acid pretreatment. Simultaneous saccharification and co-fermentation of DLC-pretreated rice straw resulted in an ethanol titer as high as 82.9 g L−1 without detoxification. Detailed structural analysis revealed that the well-preserved inter-unit linkages (>80%) and non-condensed subunits remained in the DLC lignin. This study revealed the mechanism of DLC technology in promoting biomass conversion, and thus, provides guidance to potentially realize efficient and economical biorefinery. [ABSTRACT FROM AUTHOR]

Dissolution of lignocellulose is of significant importance for its utilization and transformation. However, it remains a great challenge to efficiently and rapidly dissolve lignocellulose under mild conditions owing to the significant lack of efficient solvents for lignocellulose dissolution. Herein, robust solvent systems were designed by a combination of ionic liquids (ILs), ethanolamine (EA), and organic superbases for the dissolution of lignocellulose. It was observed that the prepared solvents (denoted as the IL/EA-superbase) could efficiently dissolve lignocellulose at mild temperatures (below 100 °C). In particular, the EmimOAc/EA-DBN system showed the best performance, and the solubility values of Populus tomentosa, sugarcane bagasse and Miscanthus giganteus at 90 °C could reach up to 3.8%, 9.5% and 20% (g per 100 g solvent), respectively. It was revealed that EA-superbase effectively participated in the interaction between ILs and lignocellulose, thus promoting the dissolution process. A systematic study revealed that the good performance of the developed solvents toward lignocellulose dissolution resulted from the synergistic effect of the three constructed components to make the solvent have a suitable capacity for the formation of hydrogen-bonding and an appropriate microstructure. [ABSTRACT FROM AUTHOR]

The synthesis of a new biobased aromatic diisocyanate derived from lignocellulosic raw material, namely guaiacol and vanillyl alcohol, through phosgene-free route offers the prospect of greener approaches for isocyanate production and the polyurethane industry. Indeed, bisguaiacol F diisocyanate (BGI) was obtained via a three-step process from readily available bisguaiacol F (BGF), involving conversion of aromatic amine into aromatic isocyanate. The unusual transition-metal-free conversion of BGF to bisguaiacol F diamine (BGA) was performed by a two-step approach: (a) the Williamson-type alkylation of BGF and then (b) the base-promoted Smiles rearrangement of bis O-alkylated BGF. In order to improve the sustainability of this process, the first step was realized under solvent-free mechanochemical conditions, and the second step was performed using two different activating methods: thermal and microwave. The thermal process provided an isolated BGA yield of ca. 70%. Microwave activation proved to be an interesting alternative, although a lower yield (32%) of the desired BGA was achieved. Finally, the diisocyanate synthesis was performed via a phosgene-free/room temperature protocol using di-tert-butyl dicarbonate in the presence of a catalytic amount of 4-dimethylaminopyridine (DMAP). Two polyurethane thermosets were designed and synthesized using the aromatic diisocyanates, biobased BGI and petrochemical-based methylene diphenyl diisocyanate (MDI), by a solvent-free two-step polymerization. Their thermo-chemical properties as well as their reactivities for polymer synthesis were evaluated. These preliminary results suggest that BGI could be potentially used as a nearly fully biobased surrogate for MDI. [ABSTRACT FROM AUTHOR]

Neo acids are highly branched carboxylic acids currently produced from fossil fuels. In this work, we produce renewable neo acids from lignocellulosic biomass-derived furan and keto acids via C–C coupling through hydroxyalkylation/alkylation (HAA), followed by ring-opening of furans through hydrodeoxygenation (HDO). We show effective C–C coupling over acid catalysts. Catalyst screening and multi-parameter optimization using machine learning optimize the yield and elucidate the correlation between variables and outcomes. We demonstrate selective furan ring-opening without affecting the carboxylic acid to make neo acids using a co-catalyst involving Pd supported on carbon and metal triflate. [ABSTRACT FROM AUTHOR]

The efficient and selective cleavage of the β-O-4 linkage under mild conditions represents a promising strategy to convert lignocellulose to value-added aromatic chemicals. In this work, a recoverable polyoxometalate-ionic liquid (POM-IL) catalyst has been successfully constructed by reacting H5PMo10V2O40 (HPMoV) polyoxoacids with 1-methyl-3-(4-sulfobutyl)-1H-imidazolium (BMIM-SO3) zwitterions. Such a POM-IL catalyst can selectively and effectively convert various β-O-4 lignin models into aromatic acids and phenols under mild homogeneous conditions. Addition of ethyl acetate to the homogeneous post-reaction solution allows the easy recovery of the POM-IL catalyst for successive five recycling tests with high robustness. The dominant catalytic pathway was elucidated by a series of mechanistic studies. [ABSTRACT FROM AUTHOR]

Consolidated bioprocessing (CBP) is a promising approach to directly convert lignocellulose feedstocks into targeted biochemicals and biofuels, and is commonly executed by single engineered microorganisms. Alternatively, the complex metabolic functions can be compartmentalized into different specialized microorganisms by using microbial consortia. In this study, a simplified microbial consortium was reassembled consisting of the lignocellulose degrader Trichoderma asperellum and lactic acid (LA) producer Lactobacillus paracasei, which were derived from the same native microbial consortium. The novel strategy of "learning from nature" combined with "simplifying the native microbial consortium" successfully increased cellulosic LA production from 7.36 g L-1 (native microbial consortium) to 57.57 g L-1 owing to the members' co-operation. Especially, over 80% carbon flux flowed from Avicel into LA synthesis with a yield of 0.92 g g-1. Furthermore, these two members can co-exist after compartmentalization into different spatial structures based on an aggregated granule of hydrogel-embedded L. paracasei and the formed biofilm of T. asperellum, leading to a 29.41% increase of LA productivity. This successfully constructed microbial consortium creates individual ecological niches to meet different oxygen demands, which enables more efficient co-operative performance in LA production from lignocellulose biomass. The analysis of interactions between these two members also provides insights on synthetic microbial consortium construction for the synthesis of other chemicals. [ABSTRACT FROM AUTHOR]

This study investigated a high-solid diol deep eutectic solvent (DES) pretreatment using a wet substrate as the starting material. This pretreatment led to a remarkable glucan saccharification of 94.8% with efficient lignin and xylan removal (as high as 63.1% and 73.0%, respectively). The chemical structures of the substrates were analyzed comprehensively to reveal the impact of the pretreatment. In addition, over 90% of the removed lignin was recovered from the pretreated liquid, which exhibited a well-preserved β-O-4 structure (46–56/100Ar). The protection mechanism of our DES was investigated by 2D HSQC NMR, GPC, and 31P NMR analysis. This study emphasized that diol-based DES pretreatment of undried lignocellulosic biomass at a high-solid loading can significantly utilize both carbohydrates and lignin fractions with high saccharification yields and high-quality lignin as a co-product. [ABSTRACT FROM AUTHOR]

Levoglucosan is a renewable chemical obtained in high yields from pyrolysis of cellulosic biomass, which offers rich functionality for synthetic modification and crosslinking. Here, we report the facile and scalable synthesis of a family of biobased networks from triallyl levoglucosan and multifunctional thiols via UV-initiated thiol–ene click chemistry. The multifunctional thiols utilized in this study can also be sourced from renewable feedstocks, leading to overall high bio-based content of the synthesized levoglucosan networks. The thermomechanical and hydrolytic degradation properties of the resultant networks are tailored based on the type and stoichiometric ratio of thiol crosslinker employed. The Young's modulus and glass transition temperature of levoglucosan-based networks are tunable over the wide ranges of 3.3 MPa to 14.5 MPa and −19.4 °C to 6.9 °C, respectively. The levoglucosan-based thermosets exhibit excellent thermal stability with Td,10% > 305 °C for all networks. The suitability of these resin formulations for extrusion-based 3D printing was illustrated using a UV-assisted direct ink write (DIW) system creating 3D printed parts with excellent fidelity. Hydrolytic degradation of these 3D printed parts via ester hydrolysis demonstrated that levoglucosan-based resins are excellent candidates for sustainable rapid prototyping and mass production applications. Overall, this work displays the utility of levoglucosan as a renewable platform chemical that enables access to tailored thermosets important in applications ranging from 3D printing to biomaterials. [ABSTRACT FROM AUTHOR]

Selective hydrodeoxygenation (HDO) of lignocellulose-derived ketones to olefins is a promising method for upgrading lignocellulosic biomass-derived molecules. Herein, zinc molybdate (ZnMoO4–E) with a disordered layered stacking structure was first prepared using a facile and environmentally friendly evaporation method and it exhibited outstanding catalytic performance for the selective HDO of lignocellulose-derived ketones to olefins. Using it, 4-heptanone, a representative of lignocellulose-derived ketones, was totally converted, and a high carbon yield of heptene (90%) was achieved at 673 K. On the basis of the characterization results, the outstanding catalytic performance of ZnMoO4–E was attributed to its porous structure, higher oxygen vacancy (or the Mo5+ species) concentration and higher acidity. Analogously, ZnMoO4–E also exhibited good catalytic performances for the selective HDO of other lignocellulose-derived ketones (such as acetone, butanone, 2-pentanone, 3-pentanone, cyclohexanone, acetophenone and 5-nonanone) to their corresponding olefins. [ABSTRACT FROM AUTHOR]

Herein, based on the studies on intermolecular weak interactions, we propose a novel perspective on the design of a biphasic system from a polar aprotic solvent (PAS) and saline water, which plays a vital role in the efficient production of furans from a lignocellulosic biomass. Interestingly, molecular dynamics simulation reveals the formation mechanism of the biphasic system from the original miscible PAS and water. The stronger interaction of Na+ and Cl− with water is proven to be responsible for the dissociation of water from water-miscible γ-valerolactone (GVL) to form the biphasic system. Similarly, the outstanding effect on the extraction and stabilization of furfural (FAL) could also be attributed to the better interaction of PAS with FAL. As a result, a remarkable FAL yield of 80.5 mol% could be obtained in the biphasic system of GVL/NaCl aqueous solution (aq.) with 0.3 mmol AlCl3 at 150 °C for 1 h. Moreover, the synergistic catalytic effect between NaCl and AlCl3 was confirmed by blank experiments and in situ23Na NMR spectroscopy. Besides, this process enables the GVL/NaCl aq. biphasic system and AlCl3 catalyst to exhibit excellent recovery with no significant FAL loss after three times of recycling. This work provides a feasible strategy for efficient biorefinery in biphasic systems. [ABSTRACT FROM AUTHOR]

Rapid population growth and industrialization have pressed the search for alternative sources to synthesize biomaterials. In this venture, this manuscript deals with process development for the synthesis of a lignin hydrogel (LH) which has biomedical applications viz., wound healing, etc. Two different synthesis strategies have been studied: single and two-step processes and likely categorized as grade A and B LHs, respectively. These strategies have been considered to study the role of the raw material (native vs. methacrylated lignin) on the overall technoeconomic analysis (TEA) and life-cycle assessment (LCA) of the process. The minimum selling price (MSP) of LH grades A and B has been estimated to be 2774 US$ per ton and 4489 US$ per ton, respectively, and have been observed to corroborate with the market price range of wound dressing gels. A "hydrogel production" sub-system has been observed to be the major contributor towards the MSP of LH due to the use of costly monomers in polymerization. Sensitivity analysis was conducted to find out parameters having a significant influence on MSP. Uncertainty analysis was also carried out to study the influence of market uncertainties on the MSP of LH. From the LCA study, it was estimated that the grade A hydrogel production process is comparatively cleaner than that of grade B. Overall, the proposed strategy of lignin upgradation can be integrated within the lignocellulosic biorefinery in future studies for the development of eco-friendly processes. [ABSTRACT FROM AUTHOR]

Clean and efficient biofuels sourced from lignocellulosic biomass can play a significant role in achieving carbon neutrality. Enzymatic hydrolysis is regarded as a vital step in this process. In this study, inspired by the digestion process of termites, a two-stage microreactor system loaded with enzymes was proposed, for the first time, to hydrolyze wheat straw into monosaccharides efficiently. The two-stage microreactor system is composed of sections loaded with xylanase and cellulase sequentially. When 2.5% (w/w) wheat straw was reacted in the first stage for 24 h, hemicellulose was degraded by 16.8%, leading to an increase in cellulose accessibility by 8.1%. During this process, the specific surface area and porosity of wheat straw also increased, which enabled the cellulase in the second stage to degrade cellulose more efficiently, thereby increasing the glucose production by 89.7% in the second stage within 6 h as compared with the control. The total sugar yield obtained at a total hydrolysis time of 36 h in the two-stage microreactor was 3.0 times that obtained using the microreactor loaded with cellulase only. Therefore, the two-stage microreactor system loaded with enzymes was demonstrated as an effective means for enhancing lignocellulosic conversion under mild conditions. [ABSTRACT FROM AUTHOR]

Engineered lignocellulose valorization enables the formation of superior energy and environmental materials which are developed to achieve the aim of sustainable carbon-neutral technologies. In this work, sequential manufacture under the trigger of hydrothermal fractionation is proposed for the "two-in-one" valorization of wheat straw into highly dispersed Fe, N-codoped carbon spheres (Fe–N–C) and Co nanoclusters anchored on biochar (Co–N–C) via using synchronous pyrolysis/activation. Taking advantage of the ordered ion-diffusion shortcut, suitable geometric/nanosized porous structure, ultrahigh surface area, well-developed packing architecture, and multiple redox possibilities (i.e., Fe species and N functional groups), the durable, conductive Fe–N–C microspheres can function as supercapacitor electrodes, exhibiting superior specific capacitance, rate-performance, and long-cycling lifespan. Benefitting from well-exposed Co nanoclusters and N coordination, the recyclable Co–N–C catalysts enabling efficient persulfate activation are conducive to expediting tetracycline removal with a working pH from 3 to 9, and a concomitant mechanism involving reactive oxygen species and interface electron shuttling is revealed via radical trapping, direct charge-transfer, and theoretical simulation. Hence this work provides multifaceted insights into a coupling strategy for lignocellulose conversion that involves matching the brand-new "biomass–energy–water" interplay with improved biorefining value. [ABSTRACT FROM AUTHOR]

The sustainability and profitability of biorefineries are based on efficient utilization of all components of lignocellulosic biomass. However, the resistance of the lignocellulosic structure and the differences in the physicochemical properties of its main components are typical challenges for most lignocellulosic fractionation approaches. Here, we demonstrate a fractionation strategy that is able to efficiently fractionate the whole lignocellulosic component and convert it into a range of valuable products. The aim of our method is to maintain the quality of lignin components by adding isopropanol, while formic acid and molten salt hydrate (LiCl·3H2O) promote the dissolution of hemicellulose and lignin. Subsequently, the as-obtained cellulose is readily saccharified due to the invasion of the dense crystal structure, and enzymatic hydrolysis yields 728.3 mg g−1 glucose. After simple separation, 75.6 mol% furfural was produced from hemicellulose in the LiCl·H2O/γ-valerolactone (GVL) biphasic system and 75.7 wt% phenolic mono-/oligomers were produced from lignin hydrolyzed in formic acid/isopropanol(aq.). Attributed to this rational design, the techno-economic analysis predicts a revenue of 122.66 USD by processing 100 kg of waste bamboo using the above developed approach. In this process, all solvents participate in both fractionation and catalytic conversion and are allowed to be recycled, which is in line with the principles of green chemistry. [ABSTRACT FROM AUTHOR]