Consolidation of lignin solvolysis and hydrodeoxygenation

Abstract

Described herein are systems and methods for the conversion of biomass, including lignin, into compounds useful as sustainable aviation fuel (SAF). Advantageously, the provided systems and methods remove the need for reductive catalytic fractionization and the use bioderived solvents rather than expensive exogenous solvents to increase energy efficiency and reduce processing costs. Instead, the described processes utilize flow through solvolysis and hydrodeoxygenation (HDO) as a single, flow-through process to convert biomass into useful fuels.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority from U.S. Provisional Patent Application No. 63 / 665,527, filed on Jun. 28, 2024, the contents of which are incorporated herein by reference in their entirety.CONTRACTUAL ORIGIN

[0002] This invention was made with government support under Contract No. DE-AC36-08GO28308 awarded by the Department of Energy. The government has certain rights in the invention.BACKGROUND

[0003] A significant contribution to greenhouse emissions is the burning of fossil fuels in the aviation industry. Accordingly, the generation of economically viable sustainable aviation fuel (SAF) from non-petroleum based sources, including biomass, is essential to reduce carbon emissions. A key component of sustainable aviation fuel is jet-range cycloalkanes and aromatics. Currently routes to SAF at scale today mostly focus on bio-based linear and isoalkanes. For example, current ethanol upgrading undergoes dehydration, oligomerization, and isomerization to linear and branched alkanes, but there is a need for a substantial amount of cycloalkanes in SAF, which technologies at scale today cannot meet.SUMMARY

[0004] Described herein are systems and methods for the conversion of biomass, including lignin, into compounds useful as sustainable aviation fuel (SAF). Advantageously, the provided systems and methods remove the need for reductive catalytic fractionization and the use bioderived solvents rather than expensive exogenous solvents to increase energy efficiency and reduce processing costs. Instead, the described processes utilize flow through solvolysis and hydrodeoxygenation (HDO) as a single, flow-through process to convert biomass into useful fuels.

[0005] The described invention incorporates HDO. The steps, process methods and reaction conditions for RCF are further described in International Patent Publication No. WO 2024 / 030611 titled “Continuous hydrodeoxygenation of lignin to jet-range aromatic hydrocarbons” and published Feb. 8, 2024, which is hereby incorporated by reference in its entirety.

[0006] In an aspect, provided is a method comprising: reacting biomass via solvolysis in the presence of water, a biomass-derived solvent, and a catalyst, thereby generating an intermediate; and reacting the intermediate via hydrodeoxygenation (HDO) thereby generating a fuel, for example, deoxygenated aromatic and / or cycloalkane hydrocarbons.

[0007] The fuel may comprises sustainable aviation fuel (SAF). The step of reacting biomass may be performed in a flow through reactor and the step of reacting the intermediate may be performed in a second reactor and the flow through reactor and the second reactor are a single process unit. By single process unit, the two reactors may be in series with no intermediate steps, for example, in a single location or reactor system. Additionally, the reactors may be configured that the two process occur concurrently.

[0008] The biomass may comprise lignin, for example, lignin derived from poplar, pine, birch or a combination thereof. The biomass-derived solvent may be derived from lignin and may comprise, for example, 4-ethyl guaiacol.

[0009] The catalysts may comprise Mo2C, Ru / C or a combination thereof. For example, the Mo2C may be present for the RCF step and the Ru / C may be present for the HDO step.

[0010] The method may be performed as a single flow-based process. The method may be performed to convert biomass into SAF without the use of RCF.

[0011] In an aspect, provided is a system comprising: a flow through reactor configured to perform solvolysis; and a second reactor directly connected to the flow through reactor configured to perform HDO. The system may be configured to convert biomass into fuel, including SAF.BRIEF DESCRIPTION OF DRAWINGS

[0012] Some embodiments are illustrated in referenced figures of the drawings. It is intended that the embodiments and figures disclosed herein are to be considered illustrative rather than limiting.

[0013] FIG. 1 illustrates the experimental setup utilizing 4-EG and water as a co-solvent system for biomass solvolysis in the first reactor bed with whole poplar biomass. The resulting lignin-rich stream in the water and 4-EG mixture flows to the second reactor, where extracted lignin undergoes depolymerization and HDO (along with 4-EG) over a Mo2C catalyst in the presence of H2 gas.

[0014] FIGS. 2A-2B show the monomer selectivity from HDO experiments using 4-EG as a feedstock over a packed bed of in situ carburized Mo2C in a trickle bed reactor at 325° C. under 65 bar with 180 mLN / min H2 flow (WHSV: 2.43 h−1): (FIG. 2A) 4-EG feed only (0.2 mL / min) and (FIG. 2B) 4-EG: H2O feed (3:1 vol ratio, 0.2 mL / min total).

[0015] FIG. 3 shows the monomer selectivity from tandem experiment using 4-ethyl guaiacol and water (3:1 vol ratio, 0.2 mL / min total) as solvent to extract lignin from poplar (1 g) at 200° C. under 65 bar and react over a packed bed of in situ carburized Mo2C in a trickle bed reactor at 325° C. under 65 bar with 180 mLN / min H2 flow (WHSV: 2.43 h−1).

[0016] FIG. 4 describes propyl benzene selectivity comparison from tandem experiments using 4-ethyl guaiacol and water (3:1 vol ratio, 0.2 mL / min total) as solvent to extract lignin from poplar (1 g) at 200° C. under 65 bar and react over a packed bed of in situ carburized Mo2C in a trickle bed reactor at 325° C. under 65 bar with 180 mLN / min H2 flow (WHSV: 2.43 h−1). In the control experiment, the first reactor was filled with quartz seeds only.

[0017] FIG. 5 shows the monomer selectivity from tandem experiment using 4-ethyl guaiacol and water (3:1 vol ratio, 0.2 mL / min total) as solvent to extract lignin from C13-labeled poplar (0.586 gram) at 200° C. under 65 bar and react over a packed bed of in-situ carburized Mo2C in a trickle bed reactor at 325° C. under 65 bar with 180 mLN / min H2 flow (weight hourly liquid space velocity: 2.43 h−1). ECH: ethyl cyclohexane, ECH-OH: ethyl cyclohexanol, ET: ethyl toluene, EB: ethyl benzene, EA: ethyl anisole, EP: ethyl phenol, EG: ethyl guaiacol.

[0018] FIG. 6A describes PB selectivity 12C-PB vs 13C-PB and FIG. 6B describes 13C-PCH and 13C-PT from tandem experiments using 4-ethyl guaiacol and water (3:1 vol ratio, 0.2 mL / min total) as solvent to extract lignin from 13C-labeled poplar (0.586 gram) at 200° C. under 65 bar and react over a packed bed of in-situ carburized Mo2C in a trickle bed reactor at 325° C. under 65 bar with 180 mLN / min H2 flow (WHSV: 2.43 h−1).DETAILED DESCRIPTION

[0019] The embodiments described herein should not necessarily be construed as limited to addressing any of the particular problems or deficiencies discussed herein. References in the specification to “one embodiment”, “an embodiment”, “an example embodiment”, “some embodiments”, etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

[0020] As used herein the term “substantially” is used to indicate that exact values are not necessarily attainable. By way of example, one of ordinary skill in the art will understand that in some chemical reactions 100% conversion of a reactant is possible, yet unlikely. Most of a reactant may be converted to a product and conversion of the reactant may asymptotically approach 100% conversion. So, although from a practical perspective 100% of the reactant is converted, from a technical perspective, a small and sometimes difficult to define amount remains. For this example of a chemical reactant, that amount may be relatively easily defined by the detection limits of the instrument used to test for it. However, in many cases, this amount may not be easily defined, hence the use of the term “substantially”. In some embodiments of the present invention, the term “substantially” is defined as approaching a specific numeric value or target to within 20%, 15%, 10%, 5%, or within 1% of the value or target. In further embodiments of the present invention, the term “substantially” is defined as approaching a specific numeric value or target to within 1%, 0.9%, 0.8%, 0.7%, 0.6%, 0.5%, 0.4%, 0.3%, 0.2%, or 0.1% of the value or target.

[0021] As used herein, the term “about” is used to indicate that exact values are not necessarily attainable. Therefore, the term “about” is used to indicate this uncertainty limit. In some embodiments of the present invention, the term “about” is used to indicate an uncertainty limit of less than or equal to +20%, +15%, +10%, +5%, or +1% of a specific numeric value or target. In some embodiments of the present invention, the term “about” is used to indicate an uncertainty limit of less than or equal to +1%, +0.9%, +0.8%, +0.7%, +0.6%, +0.5%, +0.4%, +0.3%, +0.2%, or +0.1% of a specific numeric value or target.

[0022] Described herein is a flow system that is able to use lignin-derived compounds and water as co-solvents to solubilize lignin and hemicellulose and conduct hydrodeoxygenation of the resulting solubilized intermediates to deoxygenated compounds, which could be useful in sustainable aviation fuel blendstocks. This represents a considerable process intensification advance, a breakthrough in the use of water and bio-derived oils as solvents, and a simplification in downstream processing through phase separation.

[0023] While it has been previously demonstrated that RCF can be used to produce stable lignin oils, which can then be used for hydrodeoxygenation chemistry to produce aromatics or cycloalkanes for sustainable aviation fuel blendstocks. However, RCF as a standalone process remains quite energy-intensive and expensive, and thus the described systems and methods represent a process intensification approach that enables 1) the use of no exogenous organic solvent, 2) the use of water as a co-solvent, 3) and direct solvolysis to hydrodeoxygenation, skipping the RCF step.Example 1—Lignin Solvolysis, Depolymerization, and Hydrodeoxygenation in Flow-Through Reactors

[0024] Reductive catalytic fractionation (RCF) selectively extracts lignin from biomass and cleaves aryl-ether bonds to generate oils that can undergo hydrodeoxygenation (HDO) to produce aromatic and cycloalkane for sustainable aviation fuel production. Conventional RCF uses exogenous organic solvents, which contribute to high costs and energy use in solvent recovery, and the need for separate unit operations for RCF and HDO increases process complexity. Described herein is an intensified process, wherein lignin solvolysis from intact biomass is conducted with water and a lignin-derivable aromatic solvent in a flow-through reactor, followed by consolidated lignin depolymerization and HDO in a second reactor over Mo2C. A 13C-labeled poplar substrate enabled tracking of biomass-derived lignin products, confirming lignin depolymerization and deoxygenation, while distinguishing the resulting aromatic compounds from solvent-derived species. Overall, this work highlights that lignin solvolysis, depolymerization, and HDO can be consolidated in a flow process, avoiding the need for exogenous organic solvent use and distinct unit operations for these steps.Introduction

[0025] New technologies to produce sustainable aviation fuel (SAF) are being pursued to decarbonize global aviation. Towards this goal, the conversion of ethanol and lipids are being scaled to produce SAF blendstocks, primarily for the n- and iso-alkane fractions of jet fuel. To achieve a wholly bio-based SAF, there is also demand for jet-range aromatic and cycloalkane compounds. Given its inherent aromatic structure and natural abundance, the plant biopolymer lignin offers the potential to supply the required global demand for bio-based aromatics and cycloalkanes for jet fuel blendstocks, and multiple studies have demonstrated hydrodeoxygenation (HDO) of lignin to cyclic hydrocarbons.

[0026] To convert lignin into SAF blendstocks, the polymer can be fractionated from polysaccharides, ideally depolymerized to maximize compounds in the jet-range (C8-C16), and, to meet jet fuel qualifications, fully deoxygenated. Given the inherent reactivity of lignin, processes used for extraction and depolymerization typically dictate the attainable yield of aromatic monomers for deoxygenation to jet-range hydrocarbons. To achieve high aromatic monomer yields, ‘lignin-first’ methods are being pursued, wherein lignin is extracted from intact biomass and stabilized through reactions that prevent lignin condensation, including in reductive catalytic fractionation (RCF), wherein a catalyst and hydrogen donor stabilize reactive intermediates generated during lignin extraction mediated by a polar protic solvent. RCF generates an oil rich in aromatic monomers and C-C-linked dimers and oligomers, which, after solvent removal, can undergo HDO to deoxygenated aromatics and cycloalkanes in carbon yields up to 93% of theoretical.

[0027] While tandem RCF-HDO processes can produce lignin-derived SAF blendstocks, the capital expense and energy intensity of RCF, along with the multiple unit operations required to extract, depolymerize, and deoxygenate lignin, motivate process intensification efforts. Fortunately, previous studies have shown that catalysts active for HDO of oxygenated aromatics, such as Mo2C, are also active for lignin depolymerization, suggesting that depolymerization and HDO could be consolidated. However, the temperatures typically applied for HDO (300-400° C.) and RCF (180-250° C.) differ, and HDO temperatures will depolymerize polysaccharides, thus reducing polysaccharide retention in the RCF process. With a goal of producing SAF blendstocks from lignin separate from polysaccharides, this suggests a process wherein lignin solvolysis is conducted in isolation, and depolymerization and HDO occur simultaneously in another reactor, similar to the flow-through reactors used for solvolysis and RCF. Moreover, lignin solvolysis would also be more economical and energy-efficient if a process reduced or, ideally, eliminated exogenous organic solvent use, and at HDO conditions, common RCF solvents like methanol would be deoxygenated to methane. This suggests the use of water, an effective RCF solvent, potentially with a partially recycled lignin oil stream could be a beneficial solvent for a tandem solvolysis-HDO process.

[0028] To this end, the present application is directed to a process in which lignin can be solvent-extracted from intact biomass and simultaneously depolymerized and hydrodeoxygenated using a dual-bed flow reactor. Specifically, lignin solvolysis is conducted in the first bed by flowing water and a lignin-derivable aromatic co-solvent over intact biomass, and in the second bed, both lignin depolymerization and HDO occur over Mo2C (FIG. 1). In RCF of poplar, aromatic monomers generated from aryl-ether cleavage typically exhibit a C3 side chain (i.e., propyl / propanol / propenyl) originating from the aromatic monolignols. So that our lignin-derivable aromatic co-solvent would not interfere with the detection of RCF-derived monomers, we used 4-ethyl guaiacol (4-EG) as the aromatic co-solvent with water. As a definitive demonstration of lignin extraction, depolymerization, and HDO, we used a 13C-labeled poplar substrate to track isotopically-labeled reaction products. These investigations demonstrated that utilizing a non-exogeneous solvent mixture for lignin extraction, while consolidating depolymerization and deoxygenation reactions within a single flow reactor, offers enhanced process efficiency in both design and operation. Furthermore, these findings suggest the feasibility of compact reactor designs and recycled lignin-derived solvent mixtures to optimize process configurations for jet range cyclic compounds from biomassResults

[0029] We conducted all flow-through experiments using a modified μPID flow reactor system. In the experiments that included both solvolysis and catalysis, the first reactor was loaded with ˜1 g of poplar chips, and operated at 200° C., 75 bar, and under solely liquid flow (0.2 mL / min). For experiments that included a catalyst, either alone or solvolysis followed by a catalysis step, we used a second reactor that contained an in situ carburized Mo2C catalyst at 325° C. and 65 bar with 180 mLN / min H2 flow, to achieve a weight hourly liquid space velocity (WHSV) of 2.43 h−1. The reaction effluent was fed to a high-pressure liquid / gas separator (dead volume <1 mL) equipped with a capacitive sensor and a micrometric servocontrolled valve to facilitate continuous liquid collection. The liquid samples typically phase-separated, and thus liquid samples were diluted with a known volume of methanol to obtain a single phase for GC-FID-MS analysis to quantify monomer yields (Equation 1) during time-on-stream (TOS) sampling. Further experimental details are provided in the SI.monomer⁢ recovery-TOS⁢ %=total⁢ monomer⁢ collected⁢ (moles)total⁢ 4-EG⁢fed(moles)×100(Eq. 1)deoxygenation⁢ conversion⁢ %=
total⁢ oxygen⁢ in⁢ 4-EG⁢ fed⁢ (moles)-total⁢ oxygen⁢ in⁢ products⁢ (moles)total⁢ oxygen⁢ in⁢ ⁢4-EG⁢ fed⁢ (moles)×1⁢0⁢0(Eq. 2)Effects of Water on 4-Ethyl Guaiacol HDO Over Mo2C

[0030] The use of water as a co-solvent for lignin solvolysis was deemed essential due to the substantial impact of water in achieving high lignin extraction extents, but the effect of water as a co-solvent on HDO over Mo2C was unknown. While previous studies with model compounds (e.g., anisole, m-cresol) demonstrated that the surface oxygen content of Mo2C is critical for catalyst deactivation and product selectivity, these studies primarily investigated catalyst pre-treatment with oxidizers, gas-phase reactant conditions, and in situ oxidation caused by substrates, conditions that all differ substantially from the systems and methods described herein.

[0031] When only 4-EG was fed to the reactor without water (FIG. 2A), conversion to deoxygenated products of ˜99.5 mol % was achieved. Notable deoxygenation activity was accompanied by selectivity of ˜78 mol % to ethyl benzene (EB) and ˜13 mol % to ethyl cyclohexane (ECH). Additionally, a high total monomer recovery (essentially 100% mass closure) indicated negligible 4-EG condensation in the reactor. These results suggest that the chosen reaction conditions are highly effective for achieving complete deoxygenation of 4-EG and hydrogenation of its aromatic ring.

[0032] When the same experiment (FIG. 2B) was performed with water co-feeding while keeping the total liquid flowrate constant (0.2 mL / min), a comparable conversion to deoxygenated products of ˜97.5 mol % was observed. The use of water modified the selectivity, including increasing the yield of partially deoxygenated products: ˜ 22 mol % ECH, ˜0.1 mol % ethyl anisole (EA), ˜1.0 mol % ethyl cyclohexanol (ECH-OH), and ˜1.5 mol % ethyl phenol (EP), while achieving a monomer recovery ˜104%. The increased selectivity of partially deoxygenated aromatics (EA, EP) can be attributed to the deactivation of catalytic sites responsible for direct deoxygenation (DDO) activity. This deactivation may result from reversible water binding to active sites, as suggested by García et al. Supporting this hypothesis, thermogravimetric analysis (TGA) performed on post-reaction catalysts (vide infra) showed no evidence of strong catalyst oxidation in the presence of water co-feeding. Notably, at the reaction conditions (325° C., 65 bar), water is expected to be in the vapor phase, making it a less potent oxidizer than liquid water for Mo2C, resulting in a reduced detrimental effect on the catalyst.

[0033] The observed increase in aromatic ring hydrogenation is noteworthy in the water co-feeding experiment. As the substrate amount was reduced to accommodate water co-feeding (FIG. 2B), the question arises if the effect of this change on ring hydrogenation activity. To address this, an additional water co-feeding experiment was conducted to maintain a constant 4-EG flow rate (˜0.2 mL / min). This setup resulted in a consistent trend in cyclohexane selectivity (˜15 mol % ECH and ˜3 mol % ECH-OH) indicating that water co-feeding enhances ring hydrogenation while moderately inhibiting DDO activity. This effect is particularly evident in the production rates of 4-ECH-OH, where the supplemental experiment (H2O: 4-EG=0.20:0.07 mL / min) yielded approximately 0.035 mmol / min of 4-ECH-OH, compared to 0.01 mmol / min in the original water co-feeding setup (H2O: 4-EG=0.15:0.05 mL / min).

[0034] Additionally, in both cases, trace amounts of propyl benzene (PB selectivity <0.1 mol %) were detected, even though the 4-EG substrate was purified a priori via distillation, with analytical results obtained via liquid chromatography confirming the removal of C3-chained aromatic impurities (e.g., 4-propyl guaiacol). This observation indicates that minor side-chain alkylation reactions may occur, potentially involving methoxy groups reacting directly on the catalyst surface. For example, it has been observed styrene formation during HDO of anisole to benzene on Mo2C catalyst at all conversion levels.Tandem Solvolysis and Catalysis

[0035] Following confirmation that water co-feeding does not have a detrimental effect on Mo2C HDO activity with 4-EG, we next evaluated the tandem operation configuration depicted in FIG. 1. In this case, extracted biomass components, including lignin, soluble extractives, and carbohydrate-derived components, were expected to be solubilized and react over the catalyst along with 4-EG. Additionally, the first reactor, pressurized with two immiscible liquids (4-EG and water), offered an opportunity to explore operational dynamics and assess the efficiency of lignin extraction under these conditions.

[0036] The initial water co-feeding tandem experiment revealed a transition in product distribution over time, as expected (FIG. 3). In the early stages of the process (4-5 hours), the selectivity for ethyl benzene (EB) showed a volcano trend before stabilizing at a steady state of 70 mol %. Additionally, the total selectivity for ethyl cyclohexanol (ECH-OH), ethyl anisole (EA), and ethyl phenol (EP) increased from approximately 0.57 mol % at 0.5 hours to about 1.71 mol % at 9 hours. These trends can be attributed to the immiscibility of liquids and the communication between the two reactors. When the same experiment was performed using only 4-EG as a feedstock, the product distribution remained stable throughout.

[0037] Notably, the steady-state product distribution in the tandem process was very similar to that observed in direct HDO experiments under water co-feeding conditions (FIG. 2B). This observation suggests that extracted biomass components reacting over the catalyst bed do not adversely affect overall activity. Furthermore, like the HDO-only experiments, a high monomer recovery (˜101%) was achieved, highlighting the high achievable mass closure.

[0038] To track the extracted lignin components during catalysis, we focused on the formation of PB, as the use of 4-EG was intended to differentiate C3-chained aromatics derived from biomass and solvent. As demonstrated in FIG. 4, the PB data from the tandem operation experiment exhibited a volcano trend, indicative of simultaneous lignin depolymerization and deoxygenation. To verify this observation, a control experiment was conducted under identical conditions but without poplar in the first reactor (FIG. 4). The difference in PB trends between the two experiments strongly supports the hypothesis that lignin components were effectively extracted, depolymerized, and subsequently deoxygenated during the tandem operation. Additionally, replicate experiments with varying total time-on-stream (TOS) durations consistently exhibited similar PB volcano trends, further corroborating the results.

[0039] As shown in FIG. 4, propyl benzene formation resulting from extracted biomass ceases after approximately 5 hours, suggesting the extraction process in the first reactor is completed within this timeframe. Compositional analyses of biomass residues collected after different total TOS durations (e.g., 4.5 h, 7 h, and 9 h) supports this interpretation. Specifically, delignification, xylan retention and glucan retention do not change significantly after 4.5 hours. Delignification, for instance, reaches 88 wt. % by 4.5 hours and only marginally increases to 90 wt. % by 9 hours, a variation within the range of statistical significance. At 4.5 hours, glucan retention is approximately 83 wt %, and xylan retention is around 7 wt %, influenced by the water co-feeding process. Based on PB trends in FIG. 3, the PB generated from extracted lignin during the first 5 hours was estimated at 5.27 mg, corresponding to a lignin monomer yield of 2.02 wt. %.

[0040] In addition to tandem experiments, a solvolysis experiment was conducted using the same solvent mixture while bypassing the second reactor. The solvolysis liquid contained lignin-related compounds, such as 4-hydroxybenzoic acid, phenol, and 2-methoxy-4-vinylphenol, yielding an estimated aromatic monomer recovery of 4.78 wt. %. This solvolysis liquor was further treated under batch RCF conditions (20 mL liquid, 200 mg Pd / C catalyst, 225° C., 30 bar H2 at room temperature, 3-h at reaction temperature) to estimate lignin monomer yields, with control experiments conducted using 4-EG and 4-EG+H2O under identical conditions Analysis revealed the formation of 4-propanol guaiacol and 4-propanol syringol, resulting in a lignin monomer yield of 8.67 wt. %. Assuming all C3-chained monomers were converted into PB, the lignin monomer yield would be approximately 4.97 wt. %, which exceeds the PB-based yield (2.02 wt. %) observed during tandem operations. This difference indicates that there might be condensation reactions during the tandem experiments, which is consistent with the elevated catalysis reactor temperature (325° C.). Similarly, our previous study demonstrated lignin condensation at temperatures above 300° C. during HDO reactions of stabilized lignin oil.

[0041] In tandem experiments (with and without biomass), propyl cyclohexane (PCH) was also detected. However, unlike PB, PCH did not exhibit a volcano trend in the presence of biomass, making it challenging to draw conclusions about ring hydrogenation of extracted lignin monomers. To address this and further investigate, an additional tandem experiment was conducted using 13C-labeled biomass substrates to further explore the reaction pathways and product distributions.Tandem Operation Process with 13C-Labeled Poplar

[0042] Following the same conditions established in the previous section, we conducted a tandem operation experiment using 13C-labeled poplar biomass (ca. 586 mg). Similar to the trend observed in FIG. 3, EB selectivity followed a volcano pattern before stabilizing at a steady state (FIG. 5). A high monomer balance (˜ 98%) was achieved, consistent with previous experiments.

[0043] The most notable finding from this experiment was the distinct trends of 12C-PB and 13C-PB (FIG. 6A). While 12C-PB, likely resulted from side-chain alkylation reactions, remained stable (˜0.02 mol %) throughout the reaction, 13C-PB exhibited a volcano trend, as expected. This distinction further validates the differences observed in FIG. 4. Since PB formation from lignin and side-chain alkylation was distinguished, the continued presence of small amounts of 13C-PB beyond 5 hours suggests that the previous PB-based lignin monomer yield estimation (2.02 wt. %) may have been an underestimation.

[0044] In addition to 13C-PB, trace amounts of 13C-propyl cyclohexane (13C-PCH) and 13C-propyl toluene (13C-PT) were detected, both exhibiting a volcano trend (FIG. 6B). These findings indicate that extracted lignin undergoes not only depolymerization and deoxygenation but also ring-hydrogenation and ring-alkylation reactions. However, accurately tracking these species remained challenging due to dilution effects and the higher concentration in the previous section with standard 12C poplar.CONCLUSION

[0045] This Example reveals that tandem operation proposed and designed here effectively enables lignin extraction, depolymerization, and deoxygenation under flow conditions. The use of a decoupled reactor design not only facilitates independent evaluation of solvolysis and catalytic performance but also provides a platform for detailed mechanistic studies, catalyst stability assessments, and potential process optimizations. The results further suggest that water co-feeding, while enhancing lignin extraction (ca. 90 wt. %) from biomass substrates, does not exhibit a detrimental effect on catalytic activity of Mo2C, instead promoting ring hydrogenation while partially inhibiting direct deoxygenation of 4-EG. The tandem operation with standard poplar confirms that extracted lignin components undergo simultaneous depolymerization and deoxygenation without significantly altering the overall reaction performance. The use of 13C-labeled biomass further validates the formation of biomass-derived lignin monomers and reveals that side-chain alkylation reactions contribute to minor byproduct formation. Notably, the comparison between PB-based lignin monomer yield estimations and batch RCF conditions suggests that condensation reactions may reduce overall monomer recovery under continuous processing at elevated temperatures.

[0046] The described invention may be further understood from the following non-limiting examples:

[0047] Example 1. A method comprising:

[0048] reacting biomass via solvolysis in the presence of water, a biomass-derived solvent, and a catalyst, thereby generating an intermediate; and

[0049] reacting the intermediate via hydrodeoxygenation (HDO) thereby generating a fuel.

[0050] Example 2. The method of example 1, wherein the fuel comprises deoxygenated aromatic and / or cycloalkane hydrocarbons.

[0051] Example 3. The method of example 1 or 2, wherein the step of reacting biomass is performed in a flow through reactor and the step of reacting the intermediate is performed in a second reactor; and the flow through reactor and the second reactor are a single process unit.

[0052] Example 4. The method of any of examples 1-3, wherein there is no additional processing between the reacting biomass step and the reacting the intermediate step.

[0053] Example 5. The method of any of examples 1-4, wherein the biomass comprises lignin.

[0054] Example 6. The method of example 5, wherein the lignin is derived from pine, poplar, birch or a combination thereof.

[0055] Example 7. The method of any examples 1-6, wherein the biomass-derived solvent is derived from lignin.

[0056] Example 8. The method of any of examples 1-7, wherein the biomass-derived solvent comprises 4-ethyl guaiacol.

[0057] Example 9. The method of any of examples 1-8, wherein the catalyst comprises Mo2C.

[0058] Example 10. The method of any of examples 1-9, wherein the catalyst comprises Ru / C.

[0059] Example 11. The method of any of examples 1-10, wherein the method is performed as a single flow-based process.

[0060] Example 12. The method of any of examples 1-11, wherein the method converts biomass into SAF with the proviso that reductive catalytic fractionation is not performed.

[0061] Example 13. A system comprising:

[0062] a flow through reactor configured to perform solvolysis;

[0063] a second reactor directly connected to the flow through reactor configured to perform HDO.

[0064] Example 14. The system of example 13, wherein the flow through reactor, the second reactor or both comprise a catalyst.

[0065] Example 15. The system of example 14, wherein the catalyst comprises Mo2C.

[0066] Example 16. The system of example 13 or 14, wherein the catalyst comprises Ru / C.

[0067] Example 17. The system of any of examples 13-16, wherein the system is configured to convert biomass into fuel.

[0068] Example 18. The system of example 17, wherein the fuel comprises deoxygenated aromatic and / or cycloalkane hydrocarbons.

[0069] Example 19. The system of example 17 or 18, wherein the biomass comprises lignin.

[0070] The provided discussion and examples have been presented for purposes of illustration and description. The foregoing is not intended to limit the aspects, embodiments, or configurations to the form or forms disclosed herein. In the foregoing Detailed Description for example, various features of the aspects, embodiments, or configurations are grouped together in one or more embodiments, configurations, or aspects for the purpose of streamlining the disclosure. The features of the aspects, embodiments, or configurations, may be combined in alternate aspects, embodiments, or configurations other than those discussed above. This method of disclosure is not to be interpreted as reflecting an intention that the aspects, embodiments, or configurations require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment, configuration, or aspect. While certain aspects of conventional technology have been discussed to facilitate disclosure of some embodiments of the present invention, the Applicants in no way disclaim these technical aspects, and it is contemplated that the claimed invention may encompass one or more of the conventional technical aspects discussed herein. Thus, the following claims are hereby incorporated into this Detailed Description, with each claim standing on its own as a separate aspect, embodiment, or configuration.

[0071] The terms and expressions which have been employed herein are used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed. Thus, it should be understood that although the present invention has been specifically disclosed by preferred embodiments, exemplary embodiments and optional features, modification and variation of the concepts herein disclosed may be resorted to by those skilled in the art, and that such modifications and variations are considered to be within the scope of this invention as defined by the appended claims. The specific embodiments provided herein are examples of useful embodiments of the present invention and it will be apparent to one skilled in the art that the present invention may be carried out using a large number of variations of the devices, device components, methods steps set forth in the present description. As will be obvious to one of skill in the art, methods and devices useful for the present methods can include a large number of optional composition and processing elements and steps.

[0072] As used herein and in the appended claims, the singular forms “a”, “an”, and “the” include plural reference unless the context clearly dictates otherwise. Thus, for example, reference to “a cell” includes a plurality of such cells and equivalents thereof known to those skilled in the art. As well, the terms “a” (or “an”), “one or more” and “at least one” can be used interchangeably herein. It is also to be noted that the terms “comprising”, “including”, and “having” can be used interchangeably. The expression “of any of claims XX-YY” (wherein XX and YY refer to claim numbers) is intended to provide a multiple dependent claim in the alternative form, and in some embodiments is interchangeable with the expression “as in any one of claims XX-YY.”

[0073] When a group of substituents is disclosed herein, it is understood that all individual members of that group and all subgroups, are disclosed separately. When a Markush group or other grouping is used herein, all individual members of the group and all combinations and subcombinations possible of the group are intended to be individually included in the disclosure. For example, when a device is set forth disclosing a range of materials, device components, and / or device configurations, the description is intended to include specific reference of each combination and / or variation corresponding to the disclosed range.

[0074] Every formulation or combination of components described or exemplified herein can be used to practice the invention, unless otherwise stated.

[0075] Whenever a range is given in the specification, for example, a density range, a number range, a temperature range, a time range, or a composition or concentration range, all intermediate ranges and subranges, as well as all individual values included in the ranges given are intended to be included in the disclosure. It will be understood that any subranges or individual values in a range or subrange that are included in the description herein can be excluded from the claims herein.

[0076] All patents and publications mentioned in the specification are indicative of the levels of skill of those skilled in the art to which the invention pertains. References cited herein are incorporated by reference herein in their entirety to indicate the state of the art as of their publication or filing date and it is intended that this information can be employed herein, if needed, to exclude specific embodiments that are in the prior art. For example, when composition of matter is claimed, it should be understood that compounds known and available in the art prior to Applicant's invention, including compounds for which an enabling disclosure is provided in the references cited herein, are not intended to be included in the composition of matter claims herein.

[0077] As used herein, “comprising” is synonymous with “including,”“containing,” or “characterized by,” and is inclusive or open-ended and does not exclude additional, unrecited elements or method steps. As used herein, “consisting of” excludes any element, step, or ingredient not specified in the claim element. As used herein, “consisting essentially of” does not exclude materials or steps that do not materially affect the basic and novel characteristics of the claim. In each instance herein any of the terms “comprising”, “consisting essentially of” and “consisting of” may be replaced with either of the other two terms. The invention illustratively described herein suitably may be practiced in the absence of any element or elements, limitation or limitations which is not specifically disclosed herein.

[0078] All art-known functional equivalents, of any such materials and methods are intended to be included in this invention. The terms and expressions which have been employed are used as terms of description and not of limitation, and there is no intention that in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed. Thus, it should be understood that although the present invention has been specifically disclosed by preferred embodiments and optional features, modification and variation of the concepts herein disclosed may be resorted to by those skilled in the art, and that such modifications and variations are considered to be within the scope of this invention as defined by the appended claims.

Examples

example 1

Lignin Solvolysis, Depolymerization, and Hydrodeoxygenation in Flow-Through Reactors

[0024]Reductive catalytic fractionation (RCF) selectively extracts lignin from biomass and cleaves aryl-ether bonds to generate oils that can undergo hydrodeoxygenation (HDO) to produce aromatic and cycloalkane for sustainable aviation fuel production. Conventional RCF uses exogenous organic solvents, which contribute to high costs and energy use in solvent recovery, and the need for separate unit operations for RCF and HDO increases process complexity. Described herein is an intensified process, wherein lignin solvolysis from intact biomass is conducted with water and a lignin-derivable aromatic solvent in a flow-through reactor, followed by consolidated lignin depolymerization and HDO in a second reactor over Mo2C. A 13C-labeled poplar substrate enabled tracking of biomass-derived lignin products, confirming lignin depolymerization and deoxygenation, while distinguishing the resulting aromatic comp...

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority from U.S. Provisional Patent Application No. 63 / 665,527, filed on Jun. 28, 2024, the contents of which are incorporated herein by reference in their entirety.CONTRACTUAL ORIGIN

[0002] This invention was made with government support under Contract No. DE-AC36-08GO28308 awarded by the Department of Energy. The government has certain rights in the invention.BACKGROUND

[0003] A significant contribution to greenhouse emissions is the burning of fossil fuels in the aviation industry. Accordingly, the generation of economically viable sustainable aviation fuel (SAF) from non-petroleum based sources, including biomass, is essential to reduce carbon emissions. A key component of sustainable aviation fuel is jet-range cycloalkanes and aromatics. Currently routes to SAF at scale today mostly focus on bio-based linear and isoalkanes. For example, current ethanol upgrading undergoes dehydration, oligomerization, and isomerization to linear and branched alkanes, but there is a need for a substantial amount of cycloalkanes in SAF, which technologies at scale today cannot meet.SUMMARY

[0004] Described herein are systems and methods for the conversion of biomass, including lignin, into compounds useful as sustainable aviation fuel (SAF). Advantageously, the provided systems and methods remove the need for reductive catalytic fractionization and the use bioderived solvents rather than expensive exogenous solvents to increase energy efficiency and reduce processing costs. Instead, the described processes utilize flow through solvolysis and hydrodeoxygenation (HDO) as a single, flow-through process to convert biomass into useful fuels.

[0005] The described invention incorporates HDO. The steps, process methods and reaction conditions for RCF are further described in International Patent Publication No. WO 2024 / 030611 titled “Continuous hydrodeoxygenation of lignin to jet-range aromatic hydrocarbons” and published Feb. 8, 2024, which is hereby incorporated by reference in its entirety.

[0006] In an aspect, provided is a method comprising: reacting biomass via solvolysis in the presence of water, a biomass-derived solvent, and a catalyst, thereby generating an intermediate; and reacting the intermediate via hydrodeoxygenation (HDO) thereby generating a fuel, for example, deoxygenated aromatic and / or cycloalkane hydrocarbons.

[0007] The fuel may comprises sustainable aviation fuel (SAF). The step of reacting biomass may be performed in a flow through reactor and the step of reacting the intermediate may be performed in a second reactor and the flow through reactor and the second reactor are a single process unit. By single process unit, the two reactors may be in series with no intermediate steps, for example, in a single location or reactor system. Additionally, the reactors may be configured that the two process occur concurrently.

[0008] The biomass may comprise lignin, for example, lignin derived from poplar, pine, birch or a combination thereof. The biomass-derived solvent may be derived from lignin and may comprise, for example, 4-ethyl guaiacol.

[0009] The catalysts may comprise Mo2C, Ru / C or a combination thereof. For example, the Mo2C may be present for the RCF step and the Ru / C may be present for the HDO step.

[0010] The method may be performed as a single flow-based process. The method may be performed to convert biomass into SAF without the use of RCF.

[0011] In an aspect, provided is a system comprising: a flow through reactor configured to perform solvolysis; and a second reactor directly connected to the flow through reactor configured to perform HDO. The system may be configured to convert biomass into fuel, including SAF.BRIEF DESCRIPTION OF DRAWINGS

[0012] Some embodiments are illustrated in referenced figures of the drawings. It is intended that the embodiments and figures disclosed herein are to be considered illustrative rather than limiting.

[0013] FIG. 1 illustrates the experimental setup utilizing 4-EG and water as a co-solvent system for biomass solvolysis in the first reactor bed with whole poplar biomass. The resulting lignin-rich stream in the water and 4-EG mixture flows to the second reactor, where extracted lignin undergoes depolymerization and HDO (along with 4-EG) over a Mo2C catalyst in the presence of H2 gas.

[0014] FIGS. 2A-2B show the monomer selectivity from HDO experiments using 4-EG as a feedstock over a packed bed of in situ carburized Mo2C in a trickle bed reactor at 325° C. under 65 bar with 180 mLN / min H2 flow (WHSV: 2.43 h−1): (FIG. 2A) 4-EG feed only (0.2 mL / min) and (FIG. 2B) 4-EG: H2O feed (3:1 vol ratio, 0.2 mL / min total).

[0015] FIG. 3 shows the monomer selectivity from tandem experiment using 4-ethyl guaiacol and water (3:1 vol ratio, 0.2 mL / min total) as solvent to extract lignin from poplar (1 g) at 200° C. under 65 bar and react over a packed bed of in situ carburized Mo2C in a trickle bed reactor at 325° C. under 65 bar with 180 mLN / min H2 flow (WHSV: 2.43 h−1).

[0016] FIG. 4 describes propyl benzene selectivity comparison from tandem experiments using 4-ethyl guaiacol and water (3:1 vol ratio, 0.2 mL / min total) as solvent to extract lignin from poplar (1 g) at 200° C. under 65 bar and react over a packed bed of in situ carburized Mo2C in a trickle bed reactor at 325° C. under 65 bar with 180 mLN / min H2 flow (WHSV: 2.43 h−1). In the control experiment, the first reactor was filled with quartz seeds only.

[0017] FIG. 5 shows the monomer selectivity from tandem experiment using 4-ethyl guaiacol and water (3:1 vol ratio, 0.2 mL / min total) as solvent to extract lignin from C13-labeled poplar (0.586 gram) at 200° C. under 65 bar and react over a packed bed of in-situ carburized Mo2C in a trickle bed reactor at 325° C. under 65 bar with 180 mLN / min H2 flow (weight hourly liquid space velocity: 2.43 h−1). ECH: ethyl cyclohexane, ECH-OH: ethyl cyclohexanol, ET: ethyl toluene, EB: ethyl benzene, EA: ethyl anisole, EP: ethyl phenol, EG: ethyl guaiacol.

[0018] FIG. 6A describes PB selectivity 12C-PB vs 13C-PB and FIG. 6B describes 13C-PCH and 13C-PT from tandem experiments using 4-ethyl guaiacol and water (3:1 vol ratio, 0.2 mL / min total) as solvent to extract lignin from 13C-labeled poplar (0.586 gram) at 200° C. under 65 bar and react over a packed bed of in-situ carburized Mo2C in a trickle bed reactor at 325° C. under 65 bar with 180 mLN / min H2 flow (WHSV: 2.43 h−1).DETAILED DESCRIPTION

[0019] The embodiments described herein should not necessarily be construed as limited to addressing any of the particular problems or deficiencies discussed herein. References in the specification to “one embodiment”, “an embodiment”, “an example embodiment”, “some embodiments”, etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

[0020] As used herein the term “substantially” is used to indicate that exact values are not necessarily attainable. By way of example, one of ordinary skill in the art will understand that in some chemical reactions 100% conversion of a reactant is possible, yet unlikely. Most of a reactant may be converted to a product and conversion of the reactant may asymptotically approach 100% conversion. So, although from a practical perspective 100% of the reactant is converted, from a technical perspective, a small and sometimes difficult to define amount remains. For this example of a chemical reactant, that amount may be relatively easily defined by the detection limits of the instrument used to test for it. However, in many cases, this amount may not be easily defined, hence the use of the term “substantially”. In some embodiments of the present invention, the term “substantially” is defined as approaching a specific numeric value or target to within 20%, 15%, 10%, 5%, or within 1% of the value or target. In further embodiments of the present invention, the term “substantially” is defined as approaching a specific numeric value or target to within 1%, 0.9%, 0.8%, 0.7%, 0.6%, 0.5%, 0.4%, 0.3%, 0.2%, or 0.1% of the value or target.

[0021] As used herein, the term “about” is used to indicate that exact values are not necessarily attainable. Therefore, the term “about” is used to indicate this uncertainty limit. In some embodiments of the present invention, the term “about” is used to indicate an uncertainty limit of less than or equal to +20%, +15%, +10%, +5%, or +1% of a specific numeric value or target. In some embodiments of the present invention, the term “about” is used to indicate an uncertainty limit of less than or equal to +1%, +0.9%, +0.8%, +0.7%, +0.6%, +0.5%, +0.4%, +0.3%, +0.2%, or +0.1% of a specific numeric value or target.

[0022] Described herein is a flow system that is able to use lignin-derived compounds and water as co-solvents to solubilize lignin and hemicellulose and conduct hydrodeoxygenation of the resulting solubilized intermediates to deoxygenated compounds, which could be useful in sustainable aviation fuel blendstocks. This represents a considerable process intensification advance, a breakthrough in the use of water and bio-derived oils as solvents, and a simplification in downstream processing through phase separation.

[0023] While it has been previously demonstrated that RCF can be used to produce stable lignin oils, which can then be used for hydrodeoxygenation chemistry to produce aromatics or cycloalkanes for sustainable aviation fuel blendstocks. However, RCF as a standalone process remains quite energy-intensive and expensive, and thus the described systems and methods represent a process intensification approach that enables 1) the use of no exogenous organic solvent, 2) the use of water as a co-solvent, 3) and direct solvolysis to hydrodeoxygenation, skipping the RCF step.Example 1—Lignin Solvolysis, Depolymerization, and Hydrodeoxygenation in Flow-Through Reactors

[0024] Reductive catalytic fractionation (RCF) selectively extracts lignin from biomass and cleaves aryl-ether bonds to generate oils that can undergo hydrodeoxygenation (HDO) to produce aromatic and cycloalkane for sustainable aviation fuel production. Conventional RCF uses exogenous organic solvents, which contribute to high costs and energy use in solvent recovery, and the need for separate unit operations for RCF and HDO increases process complexity. Described herein is an intensified process, wherein lignin solvolysis from intact biomass is conducted with water and a lignin-derivable aromatic solvent in a flow-through reactor, followed by consolidated lignin depolymerization and HDO in a second reactor over Mo2C. A 13C-labeled poplar substrate enabled tracking of biomass-derived lignin products, confirming lignin depolymerization and deoxygenation, while distinguishing the resulting aromatic compounds from solvent-derived species. Overall, this work highlights that lignin solvolysis, depolymerization, and HDO can be consolidated in a flow process, avoiding the need for exogenous organic solvent use and distinct unit operations for these steps.Introduction

[0025] New technologies to produce sustainable aviation fuel (SAF) are being pursued to decarbonize global aviation. Towards this goal, the conversion of ethanol and lipids are being scaled to produce SAF blendstocks, primarily for the n- and iso-alkane fractions of jet fuel. To achieve a wholly bio-based SAF, there is also demand for jet-range aromatic and cycloalkane compounds. Given its inherent aromatic structure and natural abundance, the plant biopolymer lignin offers the potential to supply the required global demand for bio-based aromatics and cycloalkanes for jet fuel blendstocks, and multiple studies have demonstrated hydrodeoxygenation (HDO) of lignin to cyclic hydrocarbons.

[0026] To convert lignin into SAF blendstocks, the polymer can be fractionated from polysaccharides, ideally depolymerized to maximize compounds in the jet-range (C8-C16), and, to meet jet fuel qualifications, fully deoxygenated. Given the inherent reactivity of lignin, processes used for extraction and depolymerization typically dictate the attainable yield of aromatic monomers for deoxygenation to jet-range hydrocarbons. To achieve high aromatic monomer yields, ‘lignin-first’ methods are being pursued, wherein lignin is extracted from intact biomass and stabilized through reactions that prevent lignin condensation, including in reductive catalytic fractionation (RCF), wherein a catalyst and hydrogen donor stabilize reactive intermediates generated during lignin extraction mediated by a polar protic solvent. RCF generates an oil rich in aromatic monomers and C-C-linked dimers and oligomers, which, after solvent removal, can undergo HDO to deoxygenated aromatics and cycloalkanes in carbon yields up to 93% of theoretical.

[0027] While tandem RCF-HDO processes can produce lignin-derived SAF blendstocks, the capital expense and energy intensity of RCF, along with the multiple unit operations required to extract, depolymerize, and deoxygenate lignin, motivate process intensification efforts. Fortunately, previous studies have shown that catalysts active for HDO of oxygenated aromatics, such as Mo2C, are also active for lignin depolymerization, suggesting that depolymerization and HDO could be consolidated. However, the temperatures typically applied for HDO (300-400° C.) and RCF (180-250° C.) differ, and HDO temperatures will depolymerize polysaccharides, thus reducing polysaccharide retention in the RCF process. With a goal of producing SAF blendstocks from lignin separate from polysaccharides, this suggests a process wherein lignin solvolysis is conducted in isolation, and depolymerization and HDO occur simultaneously in another reactor, similar to the flow-through reactors used for solvolysis and RCF. Moreover, lignin solvolysis would also be more economical and energy-efficient if a process reduced or, ideally, eliminated exogenous organic solvent use, and at HDO conditions, common RCF solvents like methanol would be deoxygenated to methane. This suggests the use of water, an effective RCF solvent, potentially with a partially recycled lignin oil stream could be a beneficial solvent for a tandem solvolysis-HDO process.

[0028] To this end, the present application is directed to a process in which lignin can be solvent-extracted from intact biomass and simultaneously depolymerized and hydrodeoxygenated using a dual-bed flow reactor. Specifically, lignin solvolysis is conducted in the first bed by flowing water and a lignin-derivable aromatic co-solvent over intact biomass, and in the second bed, both lignin depolymerization and HDO occur over Mo2C (FIG. 1). In RCF of poplar, aromatic monomers generated from aryl-ether cleavage typically exhibit a C3 side chain (i.e., propyl / propanol / propenyl) originating from the aromatic monolignols. So that our lignin-derivable aromatic co-solvent would not interfere with the detection of RCF-derived monomers, we used 4-ethyl guaiacol (4-EG) as the aromatic co-solvent with water. As a definitive demonstration of lignin extraction, depolymerization, and HDO, we used a 13C-labeled poplar substrate to track isotopically-labeled reaction products. These investigations demonstrated that utilizing a non-exogeneous solvent mixture for lignin extraction, while consolidating depolymerization and deoxygenation reactions within a single flow reactor, offers enhanced process efficiency in both design and operation. Furthermore, these findings suggest the feasibility of compact reactor designs and recycled lignin-derived solvent mixtures to optimize process configurations for jet range cyclic compounds from biomassResults

[0029] We conducted all flow-through experiments using a modified μPID flow reactor system. In the experiments that included both solvolysis and catalysis, the first reactor was loaded with ˜1 g of poplar chips, and operated at 200° C., 75 bar, and under solely liquid flow (0.2 mL / min). For experiments that included a catalyst, either alone or solvolysis followed by a catalysis step, we used a second reactor that contained an in situ carburized Mo2C catalyst at 325° C. and 65 bar with 180 mLN / min H2 flow, to achieve a weight hourly liquid space velocity (WHSV) of 2.43 h−1. The reaction effluent was fed to a high-pressure liquid / gas separator (dead volume <1 mL) equipped with a capacitive sensor and a micrometric servocontrolled valve to facilitate continuous liquid collection. The liquid samples typically phase-separated, and thus liquid samples were diluted with a known volume of methanol to obtain a single phase for GC-FID-MS analysis to quantify monomer yields (Equation 1) during time-on-stream (TOS) sampling. Further experimental details are provided in the SI.monomer⁢ recovery-TOS⁢ %=total⁢ monomer⁢ collected⁢ (moles)total⁢ 4-EG⁢fed(moles)×100(Eq. 1)deoxygenation⁢ conversion⁢ %=
total⁢ oxygen⁢ in⁢ 4-EG⁢ fed⁢ (moles)-total⁢ oxygen⁢ in⁢ products⁢ (moles)total⁢ oxygen⁢ in⁢ ⁢4-EG⁢ fed⁢ (moles)×1⁢0⁢0(Eq. 2)Effects of Water on 4-Ethyl Guaiacol HDO Over Mo2C

[0030] The use of water as a co-solvent for lignin solvolysis was deemed essential due to the substantial impact of water in achieving high lignin extraction extents, but the effect of water as a co-solvent on HDO over Mo2C was unknown. While previous studies with model compounds (e.g., anisole, m-cresol) demonstrated that the surface oxygen content of Mo2C is critical for catalyst deactivation and product selectivity, these studies primarily investigated catalyst pre-treatment with oxidizers, gas-phase reactant conditions, and in situ oxidation caused by substrates, conditions that all differ substantially from the systems and methods described herein.

[0031] When only 4-EG was fed to the reactor without water (FIG. 2A), conversion to deoxygenated products of ˜99.5 mol % was achieved. Notable deoxygenation activity was accompanied by selectivity of ˜78 mol % to ethyl benzene (EB) and ˜13 mol % to ethyl cyclohexane (ECH). Additionally, a high total monomer recovery (essentially 100% mass closure) indicated negligible 4-EG condensation in the reactor. These results suggest that the chosen reaction conditions are highly effective for achieving complete deoxygenation of 4-EG and hydrogenation of its aromatic ring.

[0032] When the same experiment (FIG. 2B) was performed with water co-feeding while keeping the total liquid flowrate constant (0.2 mL / min), a comparable conversion to deoxygenated products of ˜97.5 mol % was observed. The use of water modified the selectivity, including increasing the yield of partially deoxygenated products: ˜ 22 mol % ECH, ˜0.1 mol % ethyl anisole (EA), ˜1.0 mol % ethyl cyclohexanol (ECH-OH), and ˜1.5 mol % ethyl phenol (EP), while achieving a monomer recovery ˜104%. The increased selectivity of partially deoxygenated aromatics (EA, EP) can be attributed to the deactivation of catalytic sites responsible for direct deoxygenation (DDO) activity. This deactivation may result from reversible water binding to active sites, as suggested by García et al. Supporting this hypothesis, thermogravimetric analysis (TGA) performed on post-reaction catalysts (vide infra) showed no evidence of strong catalyst oxidation in the presence of water co-feeding. Notably, at the reaction conditions (325° C., 65 bar), water is expected to be in the vapor phase, making it a less potent oxidizer than liquid water for Mo2C, resulting in a reduced detrimental effect on the catalyst.

[0033] The observed increase in aromatic ring hydrogenation is noteworthy in the water co-feeding experiment. As the substrate amount was reduced to accommodate water co-feeding (FIG. 2B), the question arises if the effect of this change on ring hydrogenation activity. To address this, an additional water co-feeding experiment was conducted to maintain a constant 4-EG flow rate (˜0.2 mL / min). This setup resulted in a consistent trend in cyclohexane selectivity (˜15 mol % ECH and ˜3 mol % ECH-OH) indicating that water co-feeding enhances ring hydrogenation while moderately inhibiting DDO activity. This effect is particularly evident in the production rates of 4-ECH-OH, where the supplemental experiment (H2O: 4-EG=0.20:0.07 mL / min) yielded approximately 0.035 mmol / min of 4-ECH-OH, compared to 0.01 mmol / min in the original water co-feeding setup (H2O: 4-EG=0.15:0.05 mL / min).

[0034] Additionally, in both cases, trace amounts of propyl benzene (PB selectivity <0.1 mol %) were detected, even though the 4-EG substrate was purified a priori via distillation, with analytical results obtained via liquid chromatography confirming the removal of C3-chained aromatic impurities (e.g., 4-propyl guaiacol). This observation indicates that minor side-chain alkylation reactions may occur, potentially involving methoxy groups reacting directly on the catalyst surface. For example, it has been observed styrene formation during HDO of anisole to benzene on Mo2C catalyst at all conversion levels.Tandem Solvolysis and Catalysis

[0035] Following confirmation that water co-feeding does not have a detrimental effect on Mo2C HDO activity with 4-EG, we next evaluated the tandem operation configuration depicted in FIG. 1. In this case, extracted biomass components, including lignin, soluble extractives, and carbohydrate-derived components, were expected to be solubilized and react over the catalyst along with 4-EG. Additionally, the first reactor, pressurized with two immiscible liquids (4-EG and water), offered an opportunity to explore operational dynamics and assess the efficiency of lignin extraction under these conditions.

[0036] The initial water co-feeding tandem experiment revealed a transition in product distribution over time, as expected (FIG. 3). In the early stages of the process (4-5 hours), the selectivity for ethyl benzene (EB) showed a volcano trend before stabilizing at a steady state of 70 mol %. Additionally, the total selectivity for ethyl cyclohexanol (ECH-OH), ethyl anisole (EA), and ethyl phenol (EP) increased from approximately 0.57 mol % at 0.5 hours to about 1.71 mol % at 9 hours. These trends can be attributed to the immiscibility of liquids and the communication between the two reactors. When the same experiment was performed using only 4-EG as a feedstock, the product distribution remained stable throughout.

[0037] Notably, the steady-state product distribution in the tandem process was very similar to that observed in direct HDO experiments under water co-feeding conditions (FIG. 2B). This observation suggests that extracted biomass components reacting over the catalyst bed do not adversely affect overall activity. Furthermore, like the HDO-only experiments, a high monomer recovery (˜101%) was achieved, highlighting the high achievable mass closure.

[0038] To track the extracted lignin components during catalysis, we focused on the formation of PB, as the use of 4-EG was intended to differentiate C3-chained aromatics derived from biomass and solvent. As demonstrated in FIG. 4, the PB data from the tandem operation experiment exhibited a volcano trend, indicative of simultaneous lignin depolymerization and deoxygenation. To verify this observation, a control experiment was conducted under identical conditions but without poplar in the first reactor (FIG. 4). The difference in PB trends between the two experiments strongly supports the hypothesis that lignin components were effectively extracted, depolymerized, and subsequently deoxygenated during the tandem operation. Additionally, replicate experiments with varying total time-on-stream (TOS) durations consistently exhibited similar PB volcano trends, further corroborating the results.

[0039] As shown in FIG. 4, propyl benzene formation resulting from extracted biomass ceases after approximately 5 hours, suggesting the extraction process in the first reactor is completed within this timeframe. Compositional analyses of biomass residues collected after different total TOS durations (e.g., 4.5 h, 7 h, and 9 h) supports this interpretation. Specifically, delignification, xylan retention and glucan retention do not change significantly after 4.5 hours. Delignification, for instance, reaches 88 wt. % by 4.5 hours and only marginally increases to 90 wt. % by 9 hours, a variation within the range of statistical significance. At 4.5 hours, glucan retention is approximately 83 wt %, and xylan retention is around 7 wt %, influenced by the water co-feeding process. Based on PB trends in FIG. 3, the PB generated from extracted lignin during the first 5 hours was estimated at 5.27 mg, corresponding to a lignin monomer yield of 2.02 wt. %.

[0040] In addition to tandem experiments, a solvolysis experiment was conducted using the same solvent mixture while bypassing the second reactor. The solvolysis liquid contained lignin-related compounds, such as 4-hydroxybenzoic acid, phenol, and 2-methoxy-4-vinylphenol, yielding an estimated aromatic monomer recovery of 4.78 wt. %. This solvolysis liquor was further treated under batch RCF conditions (20 mL liquid, 200 mg Pd / C catalyst, 225° C., 30 bar H2 at room temperature, 3-h at reaction temperature) to estimate lignin monomer yields, with control experiments conducted using 4-EG and 4-EG+H2O under identical conditions Analysis revealed the formation of 4-propanol guaiacol and 4-propanol syringol, resulting in a lignin monomer yield of 8.67 wt. %. Assuming all C3-chained monomers were converted into PB, the lignin monomer yield would be approximately 4.97 wt. %, which exceeds the PB-based yield (2.02 wt. %) observed during tandem operations. This difference indicates that there might be condensation reactions during the tandem experiments, which is consistent with the elevated catalysis reactor temperature (325° C.). Similarly, our previous study demonstrated lignin condensation at temperatures above 300° C. during HDO reactions of stabilized lignin oil.

[0041] In tandem experiments (with and without biomass), propyl cyclohexane (PCH) was also detected. However, unlike PB, PCH did not exhibit a volcano trend in the presence of biomass, making it challenging to draw conclusions about ring hydrogenation of extracted lignin monomers. To address this and further investigate, an additional tandem experiment was conducted using 13C-labeled biomass substrates to further explore the reaction pathways and product distributions.Tandem Operation Process with 13C-Labeled Poplar

[0042] Following the same conditions established in the previous section, we conducted a tandem operation experiment using 13C-labeled poplar biomass (ca. 586 mg). Similar to the trend observed in FIG. 3, EB selectivity followed a volcano pattern before stabilizing at a steady state (FIG. 5). A high monomer balance (˜ 98%) was achieved, consistent with previous experiments.

[0043] The most notable finding from this experiment was the distinct trends of 12C-PB and 13C-PB (FIG. 6A). While 12C-PB, likely resulted from side-chain alkylation reactions, remained stable (˜0.02 mol %) throughout the reaction, 13C-PB exhibited a volcano trend, as expected. This distinction further validates the differences observed in FIG. 4. Since PB formation from lignin and side-chain alkylation was distinguished, the continued presence of small amounts of 13C-PB beyond 5 hours suggests that the previous PB-based lignin monomer yield estimation (2.02 wt. %) may have been an underestimation.

[0044] In addition to 13C-PB, trace amounts of 13C-propyl cyclohexane (13C-PCH) and 13C-propyl toluene (13C-PT) were detected, both exhibiting a volcano trend (FIG. 6B). These findings indicate that extracted lignin undergoes not only depolymerization and deoxygenation but also ring-hydrogenation and ring-alkylation reactions. However, accurately tracking these species remained challenging due to dilution effects and the higher concentration in the previous section with standard 12C poplar.CONCLUSION

[0045] This Example reveals that tandem operation proposed and designed here effectively enables lignin extraction, depolymerization, and deoxygenation under flow conditions. The use of a decoupled reactor design not only facilitates independent evaluation of solvolysis and catalytic performance but also provides a platform for detailed mechanistic studies, catalyst stability assessments, and potential process optimizations. The results further suggest that water co-feeding, while enhancing lignin extraction (ca. 90 wt. %) from biomass substrates, does not exhibit a detrimental effect on catalytic activity of Mo2C, instead promoting ring hydrogenation while partially inhibiting direct deoxygenation of 4-EG. The tandem operation with standard poplar confirms that extracted lignin components undergo simultaneous depolymerization and deoxygenation without significantly altering the overall reaction performance. The use of 13C-labeled biomass further validates the formation of biomass-derived lignin monomers and reveals that side-chain alkylation reactions contribute to minor byproduct formation. Notably, the comparison between PB-based lignin monomer yield estimations and batch RCF conditions suggests that condensation reactions may reduce overall monomer recovery under continuous processing at elevated temperatures.

[0046] The described invention may be further understood from the following non-limiting examples:

[0047] Example 1. A method comprising:

[0048] reacting biomass via solvolysis in the presence of water, a biomass-derived solvent, and a catalyst, thereby generating an intermediate; and

[0049] reacting the intermediate via hydrodeoxygenation (HDO) thereby generating a fuel.

[0050] Example 2. The method of example 1, wherein the fuel comprises deoxygenated aromatic and / or cycloalkane hydrocarbons.

[0051] Example 3. The method of example 1 or 2, wherein the step of reacting biomass is performed in a flow through reactor and the step of reacting the intermediate is performed in a second reactor; and the flow through reactor and the second reactor are a single process unit.

[0052] Example 4. The method of any of examples 1-3, wherein there is no additional processing between the reacting biomass step and the reacting the intermediate step.

[0053] Example 5. The method of any of examples 1-4, wherein the biomass comprises lignin.

[0054] Example 6. The method of example 5, wherein the lignin is derived from pine, poplar, birch or a combination thereof.

[0055] Example 7. The method of any examples 1-6, wherein the biomass-derived solvent is derived from lignin.

[0056] Example 8. The method of any of examples 1-7, wherein the biomass-derived solvent comprises 4-ethyl guaiacol.

[0057] Example 9. The method of any of examples 1-8, wherein the catalyst comprises Mo2C.

[0058] Example 10. The method of any of examples 1-9, wherein the catalyst comprises Ru / C.

[0059] Example 11. The method of any of examples 1-10, wherein the method is performed as a single flow-based process.

[0060] Example 12. The method of any of examples 1-11, wherein the method converts biomass into SAF with the proviso that reductive catalytic fractionation is not performed.

[0061] Example 13. A system comprising:

[0062] a flow through reactor configured to perform solvolysis;

[0063] a second reactor directly connected to the flow through reactor configured to perform HDO.

[0064] Example 14. The system of example 13, wherein the flow through reactor, the second reactor or both comprise a catalyst.

[0065] Example 15. The system of example 14, wherein the catalyst comprises Mo2C.

[0066] Example 16. The system of example 13 or 14, wherein the catalyst comprises Ru / C.

[0067] Example 17. The system of any of examples 13-16, wherein the system is configured to convert biomass into fuel.

[0068] Example 18. The system of example 17, wherein the fuel comprises deoxygenated aromatic and / or cycloalkane hydrocarbons.

[0069] Example 19. The system of example 17 or 18, wherein the biomass comprises lignin.

[0070] The provided discussion and examples have been presented for purposes of illustration and description. The foregoing is not intended to limit the aspects, embodiments, or configurations to the form or forms disclosed herein. In the foregoing Detailed Description for example, various features of the aspects, embodiments, or configurations are grouped together in one or more embodiments, configurations, or aspects for the purpose of streamlining the disclosure. The features of the aspects, embodiments, or configurations, may be combined in alternate aspects, embodiments, or configurations other than those discussed above. This method of disclosure is not to be interpreted as reflecting an intention that the aspects, embodiments, or configurations require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment, configuration, or aspect. While certain aspects of conventional technology have been discussed to facilitate disclosure of some embodiments of the present invention, the Applicants in no way disclaim these technical aspects, and it is contemplated that the claimed invention may encompass one or more of the conventional technical aspects discussed herein. Thus, the following claims are hereby incorporated into this Detailed Description, with each claim standing on its own as a separate aspect, embodiment, or configuration.

[0071] The terms and expressions which have been employed herein are used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed. Thus, it should be understood that although the present invention has been specifically disclosed by preferred embodiments, exemplary embodiments and optional features, modification and variation of the concepts herein disclosed may be resorted to by those skilled in the art, and that such modifications and variations are considered to be within the scope of this invention as defined by the appended claims. The specific embodiments provided herein are examples of useful embodiments of the present invention and it will be apparent to one skilled in the art that the present invention may be carried out using a large number of variations of the devices, device components, methods steps set forth in the present description. As will be obvious to one of skill in the art, methods and devices useful for the present methods can include a large number of optional composition and processing elements and steps.

[0072] As used herein and in the appended claims, the singular forms “a”, “an”, and “the” include plural reference unless the context clearly dictates otherwise. Thus, for example, reference to “a cell” includes a plurality of such cells and equivalents thereof known to those skilled in the art. As well, the terms “a” (or “an”), “one or more” and “at least one” can be used interchangeably herein. It is also to be noted that the terms “comprising”, “including”, and “having” can be used interchangeably. The expression “of any of claims XX-YY” (wherein XX and YY refer to claim numbers) is intended to provide a multiple dependent claim in the alternative form, and in some embodiments is interchangeable with the expression “as in any one of claims XX-YY.”

[0073] When a group of substituents is disclosed herein, it is understood that all individual members of that group and all subgroups, are disclosed separately. When a Markush group or other grouping is used herein, all individual members of the group and all combinations and subcombinations possible of the group are intended to be individually included in the disclosure. For example, when a device is set forth disclosing a range of materials, device components, and / or device configurations, the description is intended to include specific reference of each combination and / or variation corresponding to the disclosed range.

[0074] Every formulation or combination of components described or exemplified herein can be used to practice the invention, unless otherwise stated.

[0075] Whenever a range is given in the specification, for example, a density range, a number range, a temperature range, a time range, or a composition or concentration range, all intermediate ranges and subranges, as well as all individual values included in the ranges given are intended to be included in the disclosure. It will be understood that any subranges or individual values in a range or subrange that are included in the description herein can be excluded from the claims herein.

[0076] All patents and publications mentioned in the specification are indicative of the levels of skill of those skilled in the art to which the invention pertains. References cited herein are incorporated by reference herein in their entirety to indicate the state of the art as of their publication or filing date and it is intended that this information can be employed herein, if needed, to exclude specific embodiments that are in the prior art. For example, when composition of matter is claimed, it should be understood that compounds known and available in the art prior to Applicant's invention, including compounds for which an enabling disclosure is provided in the references cited herein, are not intended to be included in the composition of matter claims herein.

[0077] As used herein, “comprising” is synonymous with “including,”“containing,” or “characterized by,” and is inclusive or open-ended and does not exclude additional, unrecited elements or method steps. As used herein, “consisting of” excludes any element, step, or ingredient not specified in the claim element. As used herein, “consisting essentially of” does not exclude materials or steps that do not materially affect the basic and novel characteristics of the claim. In each instance herein any of the terms “comprising”, “consisting essentially of” and “consisting of” may be replaced with either of the other two terms. The invention illustratively described herein suitably may be practiced in the absence of any element or elements, limitation or limitations which is not specifically disclosed herein.

[0078] All art-known functional equivalents, of any such materials and methods are intended to be included in this invention. The terms and expressions which have been employed are used as terms of description and not of limitation, and there is no intention that in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed. Thus, it should be understood that although the present invention has been specifically disclosed by preferred embodiments and optional features, modification and variation of the concepts herein disclosed may be resorted to by those skilled in the art, and that such modifications and variations are considered to be within the scope of this invention as defined by the appended claims.

Examples

example 1

Lignin Solvolysis, Depolymerization, and Hydrodeoxygenation in Flow-Through Reactors

[0024]Reductive catalytic fractionation (RCF) selectively extracts lignin from biomass and cleaves aryl-ether bonds to generate oils that can undergo hydrodeoxygenation (HDO) to produce aromatic and cycloalkane for sustainable aviation fuel production. Conventional RCF uses exogenous organic solvents, which contribute to high costs and energy use in solvent recovery, and the need for separate unit operations for RCF and HDO increases process complexity. Described herein is an intensified process, wherein lignin solvolysis from intact biomass is conducted with water and a lignin-derivable aromatic solvent in a flow-through reactor, followed by consolidated lignin depolymerization and HDO in a second reactor over Mo2C. A 13C-labeled poplar substrate enabled tracking of biomass-derived lignin products, confirming lignin depolymerization and deoxygenation, while distinguishing the resulting aromatic comp...

Claims

1. A method comprising:reacting biomass via solvolysis in the presence of water, a biomass-derived solvent, and a catalyst, thereby generating an intermediate; andreacting the intermediate via hydrodeoxygenation (HDO) thereby generating a fuel.

2. The method of claim 1, wherein the fuel comprises deoxygenated aromatic or cycloalkane hydrocarbons.

3. The method of claim 1, wherein the step of reacting biomass is performed in a flow through reactor and the step of reacting the intermediate is performed in a second reactor; andthe flow through reactor and the second reactor are a single process unit.

4. The method of claim 1, wherein there is no additional processing between the reacting biomass step and the reacting the intermediate step.

5. The method of claim 1, wherein the biomass comprises lignin.

6. The method of claim 5, wherein the lignin is derived from pine, poplar, birch or a combination thereof.

7. The method of claim 1, wherein the biomass-derived solvent is derived from lignin.

8. The method of claim 1, wherein the biomass-derived solvent comprises 4-ethyl guaiacol.

9. The method of claim 1, wherein the catalyst comprises Mo2C.

10. The method of claim 1, wherein the catalyst comprises Ru / C.

11. The method of claim 1, wherein the method is performed as a single flow-based process.

12. The method of claim 1, wherein the method converts biomass into SAF with the proviso that reductive catalytic fractionation is not performed.

13. A system comprising:a flow through reactor configured to perform solvolysis;a second reactor directly connected to the flow through reactor configured to perform HDO.

14. The system of claim 13, wherein the flow through reactor, the second reactor or both comprise a catalyst.

15. The system of claim 14, wherein the catalyst comprises Mo2C.

16. The system of claim 14, wherein the catalyst comprises Ru / C.

17. The system of claim 13, wherein the system is configured to convert biomass into fuel.

18. The system of claim 17, wherein the fuel comprises deoxygenated aromatic or cycloalkane hydrocarbons.

19. The system of claim 17, wherein the biomass comprises lignin.

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