Lewis-acid catalyzed depolymerization of Protobind lignin in supercritical water and ethanol

Improving the production efficiency and sustainability of lignin-alcohol fuel processed at ambient temperature

Lignin represents a promising source of renewable energy. The development of CLEO (Cold processed Lignin Ethanol Oil) fuel introduces a novel lignin valorization approach, proposing its potential as maritime biofuel. However, its industrial success depends on enhancing fractionation yields and reducing solvent evaporation, which necessitates a detailed analysis of lignin properties, solvent types, and process parameters. By using novel combinations of biobased solvents, yields improved from 34 wt% to 49-53 wt% by using 30 wt% water or 40 wt% glycerol in ethanol, where Hildebrand Solubility Parameters emerged as indicative tool for increasing yields. Experiments on solid-to-liquid (S:L) ratios revealed a good balance between yield and lignin dispersion concentration at an S:L of 1:2.5. Producing CLEO with an improved solvent composition and S:L ratio resulted in 89 wt% yield while eliminating solvent evaporation requirements. This study highlights the potential for enhancing CLEO production efficiency and advancing it to industrial scale.

Elucidating the Reaction Pathways of Veratrylglycero-β-Guaiacyl Ether Degradation over Metal-Free Solid Acid Catalyst with Hydrogen

Efficient cleavage of β-O-4 bonds in lignin to high-yield aromatic compounds for the potential production of fuels and chemicals is vital for the economics of the modern biorefinery industry. This work is distinct in that a detailed mechanistic analysis of the reaction pathways of veratrylglycero-β-guaiacyl ether (VGE) catalyzed by transition-metal-free solid acid zeolite in aqueous conditions at high hydrogen pressure has been performed. VGE degradation produced high monomers yields (≈87 %), including guaiacol (48.2 %), 1-(3,4-dimethoxyphenyl)ethanol (10.3 %), 1-(3,4-dimethoxyphenyl)-2-propanol (6.1 %), 3,4-dimethoxyphenylpropanol (4.7 %), 3,4-dimethoxycinnamyl alcohol (4.1 %), and 1,2-dimethoxy-4-propylbenzene (2 %). The products were identified and confirmed by the in situ solid-state magic angle spinning (MAS) ¹³ C NMR spectroscopy in real-time conditions and the two-dimensional gas chromatography (GC×GC). A variety of products reveal the crucial role of hydrogen, water, and acid sites for heterolytic cleavage of the β-O-4 bond in VGE. Decarbonylation, hydrogenolysis, hydrogenation, and dehydration reaction pathways are proposed and further validated using first-principles calculations.

Optimization and Potentials of Kraft Lignin Hydrolysates Obtained by Subcritical Water at Moderate Temperatures

Kraft lignin was treated with subcritical water at moderate temperatures (120–220 °C) in different gas atmospheres, with the goal of optimizing its depolymerization under mild conditions. Lignin depolymerization was observed and compared using different homogeneous and heterogeneous catalysts in both nitrogen and carbon dioxide atmospheres. The most important treatment parameters for maximum lignin depolymerization and the highest yields of phenolic and other aromatic monomers were optimized. The influence of the process temperature, pressure, and time in both gas atmospheres was defined and optimized for maximum liberation of monomers into the aqueous phase. The yields of total phenols and other aromatics in the nitrogen atmosphere were the highest at 150 °C, whereas treatment in the carbon dioxide atmosphere required higher temperatures (200 °C) for a comparable efficiency. The effects of phenol addition as a capping agent in lignin depolymerization were observed and defined for both gas atmospheres. Phenol addition caused a remarkable increase in the total phenols content in the aqueous phase; however, it did not significantly affect the contents of other aromatics. The antioxidant properties of lignin hydrolysates obtained at different temperatures in different gas atmospheres were compared, correlated with the total phenols contents, and discussed, showing the promising potential of lignin hydrolysates obtained under mild subcritical water conditions.

Endophytes in Lignin Valorization: A Novel Approach

Lignin, one of the essential components of lignocellulosic biomass, comprises an abundant renewable aromatic resource on the planet earth. Although 15%––40% of lignocellulose pertains to lignin, its annual valorization rate is less than 2% which raises the concern to harness and/or develop effective technologies for its valorization. The basic hindrance lies in the structural heterogeneity, complexity, and stability of lignin that collectively makes it difficult to depolymerize and yield common products. Recently, microbial delignification, an eco-friendly and cheaper technique, has attracted the attention due to the diverse metabolisms of microbes that can channelize multiple lignin-based products into specific target compounds. Also, endophytes, a fascinating group of microbes residing asymptomatically within the plant tissues, exhibit marvellous lignin deconstruction potential. Apart from novel sources for potent and stable ligninases, endophytes share immense ability of depolymerizing lignin into desired valuable products. Despite their efficacy, ligninolytic studies on endophytes are meagre with incomplete understanding of the pathways involved at the molecular level. In the recent years, improvement of thermochemical methods has received much attention, however, we lagged in exploring the novel microbial groups for their delignification efficiency and optimization of this ability. This review summarizes the currently available knowledge about endophytic delignification potential with special emphasis on underlying mechanism of biological funnelling for the production of valuable products. It also highlights the recent advancements in developing the most intriguing methods to depolymerize lignin. Comparative account of thermochemical and biological techniques is accentuated with special emphasis on biological/microbial degradation. Exploring potent biological agents for delignification and focussing on the basic challenges in enhancing lignin valorization and overcoming them could make this renewable resource a promising tool to accomplish Sustainable Development Goals (SDG’s) which are supposed to be achieved by 2030.

Production of oxalic acid from sawdust using coal fly ash as a catalyst

The production of oxalic acid from sawdust using a mixture of strong nitric acid and concentrated sulphuric acid with coal fly ash as a catalyst has been explored. Operating parameters affecting the reaction were determined to be temperature, mesh size and amount of fly ash catalyst, time and the $${\text{HNO}}_{3} :{\text{H}}_{2} {\text{SO}}_{4}$$ HNO 3 : H 2 SO 4 ratio. A maximum oxalic acid yield of 84% was obtained using a mixture of 60% $${\text{HNO}}_{3} {\text{ and }}40 \%{\text{ H}}_{2} {\text{SO}}_{4}$$ HNO 3 and 40 % H 2 SO 4 at 70 °C and a reaction time of 150 minutes. Coal fly ash with particle size of 50–100 μm proved to be a suitable and efficient catalyst, and the optimum quantity of catalyst employed was 5g of fly ash for every 100g of sawdust.

Product Distribution of Chemical Product Using Catalytic Depolymerization of Lignin

Lignin depolymerization is a very promising process which can generate value-added products from lignin raw materials. The main objective of lignin depolymerization is to convert the complex molecules of lignin into small molecules. Nevertheless, lignin is natural polymer which the molecules of lignin are extremely complicated due to their natural variability, and it will be a big challenge to depolymerize lignin, particularly high water yield. The various technology and methods are developed to depolymerize lignin into biofuels or bio chemical products including acid/base/metallic catalyzed lignin depolymerization, pyrolysis of lignin, hydroprocessing, and gasification. The distribution and yield of chemical products depend on the reaction operation condition, type of lignin and kind of catalyst. The reactor type, product distributions and specific chemicals (benzene, toluene, xylene, terephthalic acid) production of lignin depolymerization are intensive discussed in this review. Copyright © 2020 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0). 

A review on high catalytic efficiency of solid acid catalysts for lignin valorization

It is imminent to develop renewable resources to replace fossil-derived energies as fossil resources are on the brink of exhaustion. Lignin is one of the major components of lignocellulosic biomass, which is a natural amorphous three-dimensional polymer with abundant C-O bonds and aromatic structure. Hence, valorization of lignin into high value-added liquid fuels and chemicals is regarded as a promising strategy to mitigate fossil resource shortages. Solid acid catalysts are extensively studied due to environmentally friendly in terms of the ease of separation, recovery and reduced amount of wastes. Hence, this review focuses on summarizing the recent progress of catalytic valorization of lignin over different kinds of solid acid catalysts including zeolites, heteropolyacids, metal oxides, amorphous SiO₂-Al₂O₃, metal phosphates, and Lewis acid. Based on reviewing of current progress of lignin conversion, the challenges and future prospects are emphasized.

Effect of HCOOK/Ethanol on Fe/HUSY, Ni/HUSY, and Ni-Fe/HUSY Catalysts on Lignin Depolymerization to Benzyl Alcohols and Bioaromatics

We have investigated the production of benzyl alcohols and bioaromatics via the reductive lignin depolymerization process over Fe/H-style ultrastable Y (HUSY), Ni/HUSY, and Ni-Fe/HUSY catalysts using HCOOK/ETOH in air. Synergy effect between HCOOK and the catalysts improved the depolymerization process, resulting in a higher bio-oil recovery. HCOOK does not act solely as an in situ hydrogen source; it also interacts with lignin to enable its initial depolymerization via a base-catalyzed mechanism to low-molecular-weight fragments, and in tandem with the catalyst, the hydrogenolysis rate of the depolymerized lignin monomers was enhanced. Fe/HUSY displayed an excellent activity for the catalytic reductive step in contrast to Ni/HUSY and Ni-Fe/HUSY by facilitating methoxy group removal via hydrogenolysis, thereby contributing to the yield and stabilization of the low-molecular-weight aromatics [diethyl ether (DEE)-soluble products]. Fe/HUSY gave the highest DEE product yield of >99 wt % and a total benzyl alcohol yield of 16 wt % with a total selectivity of 47 wt % (60 wt % for aromatic alcohols). Fe/HUSY was reused for the lignin depolymerization reaction without much loss of its initial activity, giving 13 wt % yield of benzyl alcohols with a selectivity of 58 wt % (77 wt % for aromatic alcohols).

A Phosphotungstic Acid Catalyst for Depolymerization in Bulrush Lignin

Obtaining renewable fuels and chemicals from lignin is an important challenge in the use of biomass to achieve sustainability and energy goals. At present, acid-based catalysts for lignin depolymerization are considered to be a potential but challenging way to produce low-molecular-mass aromatic chemicals. The main concerns with the use of Lewis acids and zeolite catalysts are the corrosive nature of the acids, the possible formation of unwanted byproducts, and the possible formation of harsh reaction conditions. We achieved high-yield conversion using phosphotungstic acid (PTA) polyoxometalate catalysts in ethanol/water under different reaction conditions with little formation of bio-char. The monomeric products were mainly composed of various types of aromatic compounds. Our method does not require the use of precious metals and harsh reaction conditions—it only requires relatively mild reaction conditions and homogeneous catalysis—thereby greatly reducing operating costs and increasing the yields. Therefore, this PTA catalyst, which has excellent performance in bulrush lignin catalysis, would be a good alternative to the traditional catalysts used in lignin depolymerization and have wide application in biomass use.

Ethanol/1,4-dioxane/formic acid as synergistic solvents for the conversion of lignin into high-value added phenolic monomers

In this study, a mixture solvent of ethanol/1,4-dioxane/formic acid (FA) is firstly reported to efficaciously depolymerize industrial lignin to produce high-value added phenolic monomers, in which 1,4-dioxane acts as lignin solvent, ethanol acts as solvent, reactant and in situ hydrogen donor, and FA acts as acid catalyst and in situ hydrogen donor. The effects of solvent composition and reaction conditions on the lignin conversion and product yields were explored, resulting in a low residue yield of 6.57% and a high phenolic monomers yield of 22.4% at 300 °C for 2 h when Kraft lignin was depolymerized in the mixture solvent of ethanol/1,4-dioxane/FA (10:10:2, v/v). Moreover, possible reaction mechanism on lignin depolymerization in the mixture solvent was illustrated, suggesting a favorable synergistic effect among the three components of the mixture solvent. In addition, the satisfactory applicability of the mixture solvent was approved through the feedstock adaptability and recyclability experiments.

Two-Step Fractionation of a Model Technical Lignin by Combined Organic Solvent Extraction and Membrane Ultrafiltration

A fractionation method for technical lignin was developed, combining organic solvent extraction and membrane ultrafiltration of the solvent soluble component. This method was validated on a commercial wheat straw/Sarkanda grass lignin (Protobind 1000) using 2-butanone (MEK) as the solvent for both the extraction and the ultrafiltration operations. The parent lignin and the different obtained fractions were fully characterized in terms of chemical composition and physicochemical properties by gel permeation chromatography, gas chromatography/mass spectrometry (GC/MS), pyrolysis-GC/MS, total phenol contents, ³¹P nuclear magnetic resonance (³¹P NMR), thermogravimetric analysis, differential scanning calorimetry analysis, and Fourier-transform infrared spectroscopy. The results show that the proposed process allows a straightforward recovery of the different lignin fractions as well as a selective control over their molecular mass distribution and related dependent properties. Moreover, the operating flexibility of the Soxhlet/ultrafiltration process allows the treatment of lignins from different feedstocks using the same installation just by modulating the choice of the solvent and the membrane porosity with the best characteristics. This is one of the most important features of the proposed strategy, which represents a new fractionation approach with the potential to improve lignin valorization for materials science and preparative organic chemistry applications.

Catalytic Cleavage of Ether Bond in a Lignin Model Compound over Carbon-Supported Noble Metal Catalysts in Supercritical Ethanol

Decomposition of lignin-related model compound (benzyl phenyl ether, BPE) to phenol and toluene was performed over carbon-supported noble metal (Ru, Pd, and Pt) catalysts in supercritical ethanol without supply of hydrogen. Phenol and toluene as target products were produced by the hydrogenolysis of BPE. The conversion of BPE was higher than 95% over all carbon-supported noble metal catalysts at 270 ° for 4 h. The 5 wt% Pd/C demonstrated the highest yield (ca. 59.3%) of the target products and enhanced conversion rates and reactivity more significantly than other catalysts. In the case of Ru/C, BPE was significantly transformed to other unidentified byproducts, more so than other catalysts. The Pt/C catalyst produced the highest number of byproducts such as alkylated phenols and gas-phase products, indicating that the catalyst promotes secondary reactions during the decomposition of BPE. In addition, a model reaction using phenol as a reactant was conducted to check the secondary reactions of phenol such as alkylation or hydrogenation in supercritical ethanol. The product distribution when phenol was used as a reactant was mostly consistent with BPE as a reactant. Based on the results, plausible reaction pathways were proposed.

Catalytic Transfer Hydrogenolysis Reactions for Lignin Valorization to Fuels and Chemicals

Lignocellulosic biomass is an abundant renewable source of chemicals and fuels. Lignin, one of biomass main structural components being widely available as by-product in the pulp and paper industry and in the process of second generation bioethanol, can provide phenolic and aromatic compounds that can be utilized for the manufacture of a wide variety of polymers, fuels, and other high added value products. The effective depolymerisation of lignin into its primary building blocks remains a challenge with regard to conversion degree and monomers selectivity and stability. This review article focuses on the state of the art in the liquid phase reductive depolymerisation of lignin under relatively mild conditions via catalytic hydrogenolysis/hydrogenation reactions, discussing the effect of lignin type/origin, hydrogen donor solvents, and related transfer hydrogenation or reforming pathways, catalysts, and reaction conditions.

From lignin to valuable products-strategies, challenges, and prospects

The exploration of effective approaches for the valorization of lignin to valuable products attracts broad interests of a growing scientific community. By fully unlocking the potential of the world's most abundant resource of bio-aromatics, it could improve the profitability and carbon efficiency of the entire biorefinery process, thus accelerate the replacement of fossil resources with bioresources in our society. The successful realization of this goal depends on the development of technologies to overcome the following challenges, including: 1) efficient biomass pretreatment and lignin separation technologies that overcomes its diverse structure and complex chemistry challenges to obtain high purity lignin; 2) advanced chemical analysis for precise quantitative characterization of the lignin in chemical transformation processes; 3) novel approaches for conversion of biomass-derived lignin to valuable products. This review summarizes the latest cutting-edge innovations of lignin chemical valorization with the focus on the aforementioned three key aspects.

Phosphoric acid-activated wood biochar for catalytic conversion of starch-rich food waste into glucose and 5-hydroxymethylfurfural

The catalytic activity of engineered biochar was scrutinized for generation of glucose and hydroxymethylfurfural (HMF) from starch-rich food waste (bread, rice, and spaghetti). The biochar catalysts were synthesized by chemical activation of pinewood sawdust with phosphoric acid at 400-600 °C. Higher activation temperatures enhanced the development of porosity and acidity (characterized by COPO₃ and CPO₃ surface groups), which imparted higher catalytic activity of H₃PO₄-activated biochar towards starch hydrolysis and fructose dehydration. Positive correlations were observed between HMF selectivity and ratio of mesopore to micropore volume, and between fructose conversion and total acid density. High yields of glucose (86.5 Cmol% at 150 °C, 20 min) and HMF (30.2 Cmol% at 180 °C, 20 min) were produced from rice starch and bread waste, respectively, over H₃PO₄-activated biochar. These results highlighted the potential of biochar catalyst in biorefinery as an emerging application of engineered biochar.

Ethanol: A Promising Green Solvent for the Deconstruction of Lignocellulose

Growing energy demand, environmental impact, energy security issues, and rural economic development have encouraged the development of sustainable renewable fuels. Nonfood lignocellulosic biomass is a suitable source for sustainable energy because the biomass feedstocks are low cost, abundant, and carbon neutral. Recent thermochemical conversion studies are frequently directed at converting biomass into high-quality liquid fuel precursors or chemicals in a single step. Supercritical ethanol has been selected as a promising solvent medium to deconstruct lignocellulosic biomass because ethanol has extraordinary solubility towards lignocellulosic biomass and can be resourced from cellulosic ethanol facilities. This review provides a critical insight into both catalytic and noncatalytic strategies of lignocellulose deconstruction. In this context, the supercritical ethanol deconstruction pathways are thoroughly reviewed; GC-MS, 1D and 2D NMR spectroscopy, and elemental analysis strategies towards liquid biomass deconstruction products are also critically presented. This review aims to provide readers a broad and accurate roadmap of novel biomass to biofuel conversion techniques.

Catalytic Strategies Towards Lignin-Derived Chemicals

Lignin valorization represents a crucial, yet underexploited component in current lignocellulosic biorefineries. An alluring opportunity is the selective depolymerization of lignin towards chemicals. Although challenged by lignin's recalcitrant nature, several successful (catalytic) strategies have emerged. This review provides an overview of different approaches to cope with detrimental lignin structural alterations at an early stage of the biorefinery process, thus enabling effective routes towards lignin-derived chemicals. A first general strategy is to isolate lignin with a better preserved native-like structure and therefore an increased amenability towards depolymerization in a subsequent step. Both mild process conditions as well as active stabilization methods will be discussed. An alternative is the simultaneous depolymerization-stabilization of native lignin towards stable lignin monomers. This approach requires a fast and efficient stabilization of reactive lignin intermediates in order to minimize lignin repolymerization and maximize the envisioned production of chemicals. Finally, the obtained lignin-derived compounds can serve as a platform towards a broad range of bio-based products. Their implementation will improve the sustainability of the chemical industry, but equally important will generate opportunities towards product innovations based on unique biobased chemical structures.

Alternatives for Chemical and Biochemical Lignin Valorization: Hot Topics from a Bibliometric Analysis of the Research Published During the 2000–2016 Period

A complete bibliometric analysis of the Scopus database was performed to identify the research trends related to lignin valorization from 2000 to 2016. The results from this analysis revealed an exponentially increasing number of publications and a high relevance of interdisciplinary collaboration. The simultaneous valorization of the three main components of lignocellulosic biomass (cellulose, hemicellulose, and lignin) has been revealed as a key aspect and optimal pretreatment is required for the subsequent lignin valorization. Research covers the determination of the lignin structure, isolation, and characterization; depolymerization by thermal and thermochemical methods; chemical, biochemical and biological conversion of depolymerized lignin; and lignin applications. Most methods for lignin depolymerization are focused on the selective cleavage of the β-O-4 linkage. Although many depolymerization methods have been developed, depolymerization with sodium hydroxide is the dominant process at industrial scale. Oxidative conversion of lignin is the most used method for the chemical lignin upgrading. Lignin uses can be classified according to its structure into lignin-derived aromatic compounds, lignin-derived carbon materials and lignin-derived polymeric materials. There are many advances in all approaches, but lignin-derived polymeric materials appear as a promising option.

Chemicals from lignin: an interplay of lignocellulose fractionation, depolymerisation, and upgrading

In pursuit of more sustainable and competitive biorefineries, the effective valorisation of lignin is key. An alluring opportunity is the exploitation of lignin as a resource for chemicals. Three technological biorefinery aspects will determine the realisation of a successful lignin-to-chemicals valorisation chain, namely (i) lignocellulose fractionation, (ii) lignin depolymerisation, and (iii) upgrading towards targeted chemicals. This review provides a summary and perspective of the extensive research that has been devoted to each of these three interconnected biorefinery aspects, ranging from industrially well-established techniques to the latest cutting edge innovations. To navigate the reader through the overwhelming collection of literature on each topic, distinct strategies/topics were delineated and summarised in comprehensive overview figures. Upon closer inspection, conceptual principles arise that rationalise the success of certain methodologies, and more importantly, can guide future research to further expand the portfolio of promising technologies. When targeting chemicals, a key objective during the fractionation and depolymerisation stage is to minimise lignin condensation (i.e. formation of resistive carbon-carbon linkages). During fractionation, this can be achieved by either (i) preserving the (native) lignin structure or (ii) by tolerating depolymerisation of the lignin polymer but preventing condensation through chemical quenching or physical removal of reactive intermediates. The latter strategy is also commonly applied in the lignin depolymerisation stage, while an alternative approach is to augment the relative rate of depolymerisation vs. condensation by enhancing the reactivity of the lignin structure towards depolymerisation. Finally, because depolymerised lignins often consist of a complex mixture of various compounds, upgrading of the raw product mixture through convergent transformations embodies a promising approach to decrease the complexity. This particular upgrading approach is termed funneling, and includes both chemocatalytic and biological strategies.

Multi-site Cooperativity in Alkali-Metal-Exchanged Faujasites for the Production of Biomass-Derived Aromatics

The catalytic Diels-Alder cycloaddition-dehydration (DACD) reaction of furanics with ethylene is a promising route to bio-derived aromatics. The reaction can be catalyzed by alkali-metal-exchanged faujasites. Herein, the results of periodic DFT calculations based on accurate structural models of alkali-metal-exchanged zeolites are presented, revealing the fundamental roles that confinement and the nature of the exchangeable cations in zeolite micropores have in the performance of faujasite-based catalysts in the DACD reaction. Special attention is devoted to analyzing the effect of functional substituents on furanic substrates (furan, 2,5-dimethylfuran, 2,5-furandicarboxylic acid) on the catalyst behavior. It is demonstrated that the conventional reactivity theories of the Diels-Alder chemistry based on simplistic single-site Lewis acidity and substituent effects do not apply if catalytic processes in the multiple-site confined environment of zeolite nanopores are considered. The nature and cooperativity of the interactions between the multiple exchangeable cations and the substrates determine the reaction energetics of the elementary steps involved in the DACD process.

Effect of residence time on two-step liquefaction of rice straw in a CO2 atmosphere: Differences between subcritical water and supercritical ethanol

This study investigated the influence of temperature and residence time on liquefaction of rice straw in subcritical CO₂-subcritical water (subCO₂-subH₂O) and in subcritical CO₂-supercritical ethanol (subCO₂-scEtOH), considering the final reaction temperatures (270-345°C) and residence times (15 and 30min). Residence time was identified as a crucial parameter in the subCO₂-subH₂O liquefaction, whereas residence time had a marginal influence on subCO₂-scEtOH liquefaction. When reaction conditions were 320°C and 15min, solvents have weak impact on the quality of bio-oil, HHV 28.57MJ/kg and 28.62MJ/kg, respectively. There was an obvious difference between the subCO₂-subH₂O and subCO₂-scEtOH liquefaction mechanisms. In subCO₂-subH₂O, CO₂ promoted the carbonyl reaction. In subCO₂-scEtOH, supercritical ethanol have the function of donating hydrogen and promoting the reaction of hydroxyl-alkylation.

Lignin Depolymerisation and Lignocellulose Fractionation by Solvated Electrons in Liquid Ammonia

We explored the depolymerisation of several lignins in liquid ammonia at relatively high temperatures and pressures (120 °C and 88 bar). Five different lignins were tested: Indulin AT kraft, Protobind 1000 soda, wheat straw organosolv, poplar organosolv and elephant grass-milled wood lignin (EG MWL). In pure liquid ammonia, all lignins underwent slow incorporation of nitrogen into their structure, resulting in higher molecular weight and polydispersity index. Subsequently, we show a reductive depolymerisation by solvated electrons at room temperature by adding sodium metal to the liquid ammonia without any external hydrogen donor. The netto yields of bio-oil are low for technical lignins (10-23 %), but with higher yields of alkylphenols. In the case of native EG MWL, netto yields of 40 % bio-oil were achieved. Finally, when the room temperature method was applied to poplar wood fibre, we observe improved delignification upon the addition of sodium compared to poplar wood fractionation in pure liquid ammonia.