Liquefaction Of Lignin Research Articles

Research Status of Lignin-Based Polyurethane and Its Application in Flexible Electronics.

Polyurethanes (PU) have drawn great attention due to their excellent mechanical properties and self-healing and recyclable abilities. Lignin is a natural and renewable raw material in nature, composed of a large number of hydroxyl groups, and has a great potential to replace petroleum polyols in PU synthesis. This review summarizes the recent advances in modification methods such as the liquefaction, alkylation, and demethylation of lignin, and a systematic analysis of how to improve the reactivity and monomer substitution of lignin during polyurethane synthesis for the green manufacturing of high-performance polyurethanes was conducted. Polyurethane can be used in the form of films, foams, and elastomers instead of conventional materials as a dielectric or substrate material to improve the reliability and durability of flexible sensors; this review summarizes the green synthesis of polyurethanes and their applications in flexible electronics, which are expected to provide inspiration for the wearable electronics sector.

Hydrogen peroxide assisted oxidative liquefaction of alkaline lignin over cobalt-nickel loaded zirconia catalysts

Research toward the oxidative fractionation of lignin is gaining attention due to the selective breaking of a sub-aromatic unit of lignin's complex structure into monomeric phenolic. This study aims to investigate the liquefaction tendency of alkaline lignin by screening the synergistic effect of Co and Ni loaded on synthesized (syn) ZrO2 catalyst under the applied mild oxidative reaction conditions of molecular oxygen and hydrogen peroxide. Compared to the non-catalytic reaction (38.1 wt%), a significant improvement in the bio-oil yield (53.7 wt%) was obtained with the 5Co–5Ni/ZrO2-syn catalyst under the oxidative condition of molecular oxygen. However, only 44.3 wt% bio-oil was observed with commercial (com) 5Co–5Ni/ZrO2-com catalyst. The synergistic study of Co and Ni metal exhibited a diverse impact on the fractionation of lignin into respective product yields (bio-oil, gas, and char). Notably, adding a catalytic amount of hydrogen peroxide showed a remarkable improvement in liquefaction. The maximum bio-oil yield (72.1 wt%), and a maximum conversion (77.9%) were noticed with 0.5 mL H2O2 at 120 °C/30 min under the atmospheric molecular oxygen. The GC-MS analysis of bio-oil (5Co–5Ni/ZrO2-syn-HP) attributed to a high quantity of guaiacyl phenolic with a maximum proportion of benzaldehyde-3-hydroxy-4-methoxy (65.3%). The 5Co–5Ni/ZrO2-syn catalyst was also examined for the three catalytic cycles, which did not show any significant loss in product yield.

Yield and distribution of products of lignin liquefaction catalyzed by molybdenum-vanadium-phosphorus heteropolyacids

ABSTRACT This paper focuses on the performance of Molybdenum-vanadium-phosphorus heteropolyacids (PMo12-xVx) with different V-doped amounts in catalyzing the conversion of lignin to bio-oil, and the distribution of liquefied products. Molybdenum-vanadium-phosphorus heteropolyacids (PMo11V1, PMo10V2, PMo9V3) with different amount (0, 2.5, 5, 10 wt%) were used to catalyze lignin liquefaction. The experimental results showed that PMo12-xVx could effectively catalyze the depolymerization of lignin to bio-oil, and the doping amount of the V atom in PMo12-xVx affects the distribution of lignin depolymerization products. The highest bio-oil yield (53.62wt%) and conversion (57.83wt%) could be obtained from lignin liquefaction at 2.5 wt% PMo9V3. With the increase of PMo12-xVx V-atom doped amount, the content of aliphatic hydrocarbons increased from 3.14% to 40.58%, the content of vanillin increased from none to 8.9%. Based on the analysis of bio-oil, FT-IR data, and DFT simulation results, it was found that the selective cleavage of the Cα-Cβ bond and the ring-opening of the carbon at the methyl end of lignin were the main reasons for the high yield of vanillin and aliphatic hydrocarbons during the depolymerization of lignin catalyzed by PMo12-xVx. Finally, a possible reaction pathway for the PMo12-xVx-catalyzed depolymerization of lignin to vanillin and aliphatic hydrocarbons was proposed.

Role of oxophilic metal ions (Mo, Zr, Ti) impregnated Ni/γ-Al2O3 catalysts for hydrothermal liquefaction of kraft lignin

In this study, the effect of oxophilic metal ions (Mo, Zr, and Ti) loaded Ni/γ-Al2O3 (Al) catalysts was explored for the first time for the hydrothermal liquefaction of kraft lignin using IPA for 30 min/280 °C. The liquefaction of lignin was noticed to be 65.4 wt% with 10 wt% loaded Ni/Al with an 81.3% total conversion. The performance of Ni/Al was enhanced remarkably by using the oxophilic metal ions as promoters owing to an increase in the Lewis character of the catalyst's surface. The bio-oil yield was a maximum of 72 wt% with a 91.5% conversion using 3 wt% loaded Ti–10Ni/Al. The different alcoholic solvents such as methanol, ethanol, and IPA were also examined for the same. However, the best liquefaction was noticed with IPA owing to better H-donor tendency. Additionally, a series of IPA-water co-solvent examinations attributed to a significant improvement in the liquefaction to 74.8 wt% (50:50) IPA-water system. The optimum catalyst 10Ni–3Ti/Al was tested for four catalytic cycles, which indicated a slight loss in the catalytic activity because of blockage of the catalytic active site by char deposition. The GC-MS investigation of optimum catalytic bio-oil showed the highest selectivity of acetosyringone (68.5%) and 2-methoxy-phenol (22.8%), which was observed to be only 30.1 and 5.1% for non-catalytic bio-oil. The 1H NMR and FT-IR investigation of raw lignin and bio-oil proved the breakage of lignin's 3D structure into respective G-and S-type monomeric compounds. Additionally, catalysts were characterized using the XRD, BET, and XPS analysis.

Copper and zinc-impregnated mesoporous gamma-alumina catalyst for hydrothermal liquefaction of alkali lignin

The complete utilization of lignocellulose is a sustainable key for bio-refineries, where the utilization of evitable lignin is a great challenge owing to its structural complexity. Here, the effect of Cu and Zn-loaded mesoporous γ-Al2O3 catalysts was examined for the first time for the hydrothermal liquefaction of alkali lignin in an ethanol/water solvent system. It showed excellent performance towards the liquefaction as compared to that of (commercial) com-5Cu/γ-Al2O3 catalyst. Here, the bio-oil yield was observed to be 47.7 wt% for com-5Cu/Al catalyst which was increased to 59.1% for syn-5Cu/Al. It was increased substantially to 65.4 wt% for syn-10Cu/Al. However, only a 40 wt% bio-oil yield was found for the non-catalytic (NC) reaction. Additionally, a further significant improvement to 74.7 wt% was noticed for Zn (5 wt%) modified syn-10Cu/Al catalyst. Here, the screening of the water-ethanol mixture, and reaction parameters were also evaluated which showed a small increase in bio-oil yield to 77.4 wt% for ethanol/water (75/25, v/v). The GC-MS analysis of bio-oil exhibited the high specificity of vanillin (69.3%) for syn-10Cu-5Zn/Al. The 1H NMR and FT-IR investigation also validate the diverse functionality of bio-oils. The reusability of the optimum catalyst (syn-10Cu-5Zn/Al) was also tested for three successive catalytic cycles that exhibited the good performance of the catalyst up to the second cycle.

Acid-catalyzed Kraft lignin liquefaction for producing polyols and polyurethane foams

This study investigates the use of acid-catalyzed lignin liquefaction for the production of polyols and polyurethane foams. The liquefaction process was carried out using a kraft lignin powder following a process similar to the Lignoboost® method, based on a previous study, with catalyst (sulfuric acid) weight contents of 0, 3 and 6 wt.% in relation to the lignin. The PU foams were prepared by the free expansion method and analyzed by Fourier transform infrared spectroscopy (FT–IR), thermogravimetry (TG), differential scanning calorimetry (DSC), dynamic-mechanical analysis (DMA), as well as contact angle and apparent density evaluations. The effect of the catalyst concentration on yield, moisture content and molecular weight of the resulting polyols was assessed, and the optimal conditions were obtained for 6 wt.%. FT–IR analysis indicated a suitable foam polymerization. The incorporation of an acid catalyst led to a more hydrophilic foam and a rigid cell structure, with thinner and more uniformly sized cells, as well as higher thermal stability and glass transition temperature.

Tungstoborate heteropolyacid-catalyzed lignin liquefaction: Product yield and component distribution

Tungstoborate heteropolyacid catalysts have good catalytic degradation performance, especially for selective cleavage of C–C bonds in biomass. In this paper, the product yield and component distribution of tungstoborate heteropolyacid (BW12)-catalyzed lignin liquefaction were investigated at different parameters, including temperatures (120, 140, 160, 180, and 200 °C), catalyst amount (0, 2.5, 5, 10, and 20 wt. %), and reaction time (0, 30, 60, 90, and 120 min). It was found that a higher conversion (72.16 wt. %) and bio-oil yield (68.41 wt. %) could be obtained under suitable reaction conditions (180 °C, 60 min, 5 wt. %). Bio-oil analysis showed that the BW12 catalyst had a significant effect on the distribution of bio-oil fractions, in which mono-aromatic components increased from 32.96% to 47.56% compared to those without the catalyst. In particular, carbonyl substances in the mono-aromatic components increased from 18.66% to 26.97%. Spectroscopic analysis (FT-IR) found that the absorption peaks of C–O and C–C bonds in the liquefied residue catalyzed by BW12 decreased compared to the raw lignin. Moreover, the mechanism of BW12-catalyzed lignin depolymerization was investigated by DFT simulations. The simulation results demonstrated that the shortening of Cα–O bond, the breaking of Cβ–Cγ and Cα–Cβ bonds in lignin promoted the formation of vanillin and benzaldehyde, 3-hydroxy-4-methoxy. Finally, based on the experimental data and simulation results, a possible reaction pathway for the BW12-catalyzed liquefaction of lignin into mono-aromatic substances was proposed.

Production of phenolic monomers from lignin in hydrothermal medium: Effect of rapid heating and short residence time

This study investigates the influence of heating rate and short residence time (1–15 min) on the hydrothermal liquefaction (HTL) of alkali lignin, as a function of reaction temperature (280–320 °C). A novel induction-heating reactor system (IHRS) was designed and was used for rapid heating rate (∼100 °C/min), while a resistive-heating reactor system (RHRS) was used for slow heating rate (∼5.3 °C/min). The experiment using IHRS with a short residence time (1 min) resulted in the highest yield of carbon recovery in biocrude (52.2 ± 0.63 wt%) at 320 °C under autogenous pressure. In contrast, the experiments using RHRS or longer residence time (8–15 min) with IHRS showed lower biocrude yield due to the promotion of gasification and undesired secondary reactions. The detailed characterization of biocrude revealed that rapid heating rate improves the selectivity of compound in biocrude, such as phenol, while slow heating rate produced a broader distribution of compounds, including anisole and alkyl phenols at 320 °C for 1 min residence time. Furthermore, the usefulness of phenol as capping agent during IHRS of lignin was demonstrated in suppressing char formation and increasing biocrude yield.

Life Cycle Assessment of Polyol Production from Lignin via Organosolv and Liquefaction Treatments

This study aimed to conduct a comprehensive Life Cycle Assessment (LCA) of lignin-based polyol production through organosolv fractionation of cardoon stalks and subsequent lignin liquefaction. The LCA employed a cradle-to-gate approach, encompassing cardoon cultivation and all processing steps leading to polyol production. The research involved laboratory-scale optimization of the organosolv and liquefaction processes, followed by industrial-scale implementation. The analysis revealed that all stages of the production chain, including crop cultivation, organosolv, and liquefaction, significantly influenced overall environmental impacts. Specific materials and processes played pivotal roles, such as harvesting machinery and fertilizers in crop production, γ-Valerolactone (GVL) as the primary contributor (72–100%) to environmental impacts in the organosolv phase, and materials like polyethylene glycol 400 (PEG 400) and glycerin in the liquefaction phase, accounting for the majority (96–100%) of environmental impacts in this stage. When considering endpoint damage categories, it became evident that this production chain had a notable impact on human health, primarily due to emissions in air, water, and soil from agricultural processes. Lignin-based polyols demonstrated a moderate improvement compared to their petroleum-based counterparts, with an approximate reduction of 3–16% in environmental impact.

The bifunctional active sites on carbon supported Fe-Mo bimetallic catalyst to improve Kraft lignin liquefaction

Carbon-supported Fe-Mo bimetallic catalysts were synthesized for the thermal catalytic ethanolysis of lignin to liquid fuels composed of aromatic monomers. A yield of 40.7 wt % of lignin oil, consisting of 38.8 wt % phenol monomers and 39.3 wt % benzeneacetaldehyde monomers, was obtained in the presence of Fe-Mo-P catalysts (1:0.5) at 290 °C for 4 h in the supercritical ethanol solvent (6.5 MPa). The catalysts exhibited a rich distribution of α-MoC nanoparticles, Fe0 nanoclusters, surface oxygen defects, and active species of Mo6+ and phosphoric acid on the graphitized microporous carbon substrate. The synergistic effects of these active components were crucial for enhancing lignin liquefaction efficiency. The ethanolysis of the lignin model compound revealed that the Fe-Mo bimetallic catalyst can facilitate double cracking of C-C/C-O bonds under supercritical ethanol conditions. In situ Raman and FT-IR characterization were performed to monitor the transformation of the Fe-Mo bimetallic catalyst from the precursor to the carbon material, including the dehydration and carbonization of the organic precursor.

Hydrothermal liquefaction of pinecone kraft lignin into selective phenolic: Optimization of Ni and Mo impregnation on ceria

Pine is an abundant forestry waste and is a main cause of forest fires in China's mountain area owing to its flammable nature. Therefore, its utilization for the production of valuable phenolics can contribute a small to fix it. This study examined Ni-impregnated ZrO2, CeO2, and MgO catalysts for hydrothermal liquefaction of pinecone lignin, which was extracted by applying the kraft process. The 5 wt%-Ni/CeO2 catalyst was found to be efficient with a 59.2 wt% bio-oil yield corresponding to 77.6% of total conversion in ethanol. This bio-oil yield was enhanced significantly to 65.7 wt% on applying the 3 wt% Mo along with 5Ni/CeO2. The effect of diverse solvents e.g., water, ethanol, methanol, IPA, and co-solvent mixture was also explored to achieve the greatest liquefaction of this PC kraft lignin. Amongst all, methanol/water (1:1) was highly compatible with the maximum liquefaction of kraft lignin (77.8%) at optimum 280 °C/30 reaction conditions. The GCMS analysis of optimum bio-oil attributes the higher selectivity of vanillin (67.4%) and validates the presence of guaiacyl sub-aromatic units in the lignin. The elemental analysis of cat-M-W bio-oil exhibits a considerable improvement in calorific value (38.4 MJ/kg) compared to that of raw lignin (28.1 MJ/kg). Additionally, the reusability test of the 5Ni–3Mo/CeO2 catalyst attributes the best performance of the catalyst up to two cycles without applying any kind of regeneration. Additionally, XRD and BET analysis of catalysts showed the impregnation of both metals (Ni & Mo) at the CeO2 surface in the oxide form.

Slurry co-hydroprocessing of Kraft lignin and pyrolysis oil over unsupported NiMoS catalyst: A strategy for char suppression

Pyrolysis oil (PO) assisted Kraft lignin (KL) liquefaction over an unsupported NiMoS catalyst in a paraffin solvent was explored in this work. A paraffin solvent was used to represent hydrogenated vegetable oil (HVO) which is a biofuel. We have for the first time showed that when co-processing Kraft lignin with pyrolysis oil in a paraffin solvent the char formation could be completely suppressed. The complex composition of PO, containing various compounds with different functional groups, was able to aid the depolymerization pathways of lignin by obstructing the condensation path of reactive lignin derivatives. To further understand the role of different functional groups present in pyrolysis oil during lignin liquefaction, we investigate the co-hydroprocessing of Kraft lignin with various oxygenate monomers using unsupported NiMoS. 4-propylguaiacol (PG) was found to be the most efficient monomer for stabilizing the reactive lignin intermediates, resulting in a low char yield (3.7%), which was 4 times lower than the char production from Kraft lignin hydrotreatment alone. The suppressed rate of lignin fragment repolymerization can be attributed to the synergistic effect of functional groups like hydroxyl (-OH), methoxy (-OCH3), and propyl (-C3H7) groups present in PG. These groups were found to be able to stabilize the lignin depolymerized fragments and blocked the repolymerization routes enabling efficient lignin depolymerization. It was found that the presence of a co-reactant like PG during the heating period of the reactor acted as a blocking agent facilitating further depolymerization routes. Finally, a reaction network is proposed describing multiple routes of lignin hydroconversion to solid char, lignin-derived monomers, dimers, and oligomers, explaining why the co-processing of pyrolysis oil and Kraft lignin completely suppressed the solid char formation.

A tandem strategy of mild preoxidation-hydrogenolysis for efficient depolymerization of lignin

A tandem strategy of “mild preoxidation-hydrogenolysis” was proposed for the efficient depolymerization of lignin. Firstly, a mild oxidation system was constructed with H2O2 as the green oxidant and NaOH/Fe2(SO4)3/CuO as the catalyst to pretreat lignin; then NiMoS catalyst was used for the further hydrogenolysis of the pretreated lignin. The reaction results showed that the strategy could achieve efficient lignin depolymerization. Under optimal conditions, the lignin liquefaction degree reached 91.1 wt.% and the monomer yield reached 20.6 wt.%. The structural analysis of the recovered lignin showed that the mild oxidation pretreatment could initially break the linkage bonds within the lignin molecule and get some large fragment molecules. Meanwhile, it also made the hydroxyl group in the Cα position of the β-O-4 bond oxidized to carbonyl group, thus reducing the dissociation energy of the β-O-4 bond.

Catalytic hydrothermal liquefaction of alkali lignin for monophenols production over homologous biochar-supported copper catalysts in water

Constructing an advanced catalytic system for the purposeful liquefaction of lignin into chemicals has presented a significant prospect for sustainable development. In this work, the catalytic process of mesoporous homologous biochar (HBC) derived from alkali lignin supported copper catalysts (Cu/HBC) was reported for catalytic liquefaction of alkali lignin to monophenols. The characterization results revealed HBC promoted the formation of metal-support strong interaction and the generation of oxygen vacancies, enhancing the acid sites of Cu/HBC. Under the optimal conditions (0.2 g alkali lignin, 280 °C, 0.05 g Cu/HBC, 6 h, 18 mL water), the monophenol yield reached 75.01 ± 0.76 mg/g, and the bio-oil yield was 57.98 ± 1.76%. The copious mesopores, high surface area, and rich acidic sites were responsible for the high activity of Cu/HBC, which significantly outperformed the controlled catalysts, such as HBC, commercial activated carbon (AC), and reported Ni/AC, Ni/MCM-41, etc. In four consecutive runs, the catalytic performance of Cu/HBC was only reduced by 3.65% per cycle. Interestingly, catechol was selectively produced with Cu/HBC, which provided an effective strategy for the conversion of G/S-type lignin to catechyl phenolics (C-type). These findings indicate that the Cu/HBC will be a promising substitution of noble metal-supported catalysts for conversion biomass into high value-added phenolics.

Red mud catalysts for hydrothermal liquefaction of alkali lignin: Optimization of reaction parameters

The aromatic enrichment structure of lignin shows its great potential for valuable chemicals, which could be a substitution for petrochemical raw materials. However, the selective breaking of its macromolecular structure is a key challenge in lignin valorization. This study examined hydrothermal liquefaction of alkali lignin with Zr, Mo, and Ce-impregnated red mud catalysts to achieve the maximum liquefaction and break down the sub-aromatic units into selective phenolics. 10 wt% Mo and 10 wt% Ce/RM exhibited the effective liquefaction tendency in ethanol solvent. With a C/F ratio of 1:5, the maximum bio-oil yield (81.8 wt%) was obtained with (5 wt%) Mo–Ce/RM catalyst, and maximum conversion (91.6%) was achieved with a 1:2 C/F ratio in 50E: 50W co-solvent. However, the C/F (1: 10) was found to be efficient towards the selective breaking of alkali lignin into guaiacol compounds with 65.4 area% selectivity of vanillin. The FTIR and 1H NMR analysis showed the actual breaking of lignin sub-aromatic structure into monomeric compounds. The results of GPC analysis validate the cleavage of lignin's structure with a significant reduction in the molecular weight of lignin from ∼28400 gm/mol to ∼485 gm/mol. The catalyst was highly recyclable as it maintained remarkable activity up to two successive catalytic cycles.

Solvothermal Liquefaction of Industrial Soda Lignin into Functional Chemicals

AbstractLignin is one of the most abundant and versatile biomass components, which can be used as a resource for bio‐based chemical production. This study investigates the liquefaction of soda lignin with water and ethanol in the temperature range of 220–280 °C during a reaction time of 15–45 min. The maximum bio‐oil yields of 59 and 57 wt % were observed in ethanol and water at 280 °C after 30 and 15 min of reaction time, respectively. It was observed that both solvents were suitable for depolymerizing lignin into methoxyphenols and acetosyringone. However, the area percent values of methoxyphenols (54.2) and acetosyringone (48.3) were higher in water than in ethanol. Ethanol was a more effective solvent with regard to a lower char yield, which was constant (37–41 wt %) in the temperature and reaction time ranges.

Optimisation of lignin liquefaction with polyethylene glycol/ glycerol through response surface methodology modelling

In order to diminish the dependence on oil lignin, which is the most abundant biopolymer of phenolic origin on Earth and can be utilised in different industrial endeavours, such as, the production of polyurethanes. In this study, hardwood (Eucalyptus globulus) and softwood (Pinus radiata) organosolv lignins were employed to produce bio-polyols trough microwave-assisted liquefaction. The resulting bio-polyols possessed specific properties to be employed in the synthesis of rigid and elastic polyurethanes. The values of the reaction parameter were optimized using response surface methodology to determine the most effective conditions for producing bio-polyols from both types of lignins for the purpose of rigid and elastic polyurethane formulation. The effect of catalyst concentration (%wt.), temperature (ºC) and Polyethylene glycol/Glycerol weight ratio on the molecular weight (Mw) and hydroxyl number (IOH) of bio-polyols was evaluated. The optimum reaction conditions of bio-polyols production for rigid polyurethanes were virtually equal for the two lignins, 159–161 ºC, Polyethylene glycol/Glycerol ratio of 3 without catalyst. On the contrary, the bio-polyols for elastic polyurethanes required different reaction parameters depending on the lignin used. For hardwood lignin the optimised conditions were 180 ºC, 7.57 (Polyethylene glycol/Glycerol ratio) and 5.00% of catalyst while for softwood lignin were 160 ºC, 7.34 (Polyethylene glycol/Glycerol) and 3.85% of catalyst. Additionally, the bio-polyols obtained at optimised conditions were fully characterised and acid number, polydispersity index, functionality and the rheological behaviour was studied.

On the understanding of bio-oil formation from the hydrothermal liquefaction of organosolv lignin isolated from softwood and hardwood sawdust

Organosolv fractionation of hard- and softwood is applied to obtain lignin substrates utilized for bio-oil production through hydrothermal liquefaction. The resulting bio-oil properties reflect the stemming lignin chemistries.

Bimetallic NiCo catalyzed enzymatic hydrolysis lignin hydrogenolysis to produce aromatic monomers

Bimetallic catalyst gets increasing attention for the lignin valorization due to its outstanding catalytic activity. Herein, the non-noble bimetallic catalyst NiCo/C was proposed to conduct the hydrogenolysis of enzymatic hydrolysis lignin. 20.8 wt% yield of monomer products and 94.6% lignin liquefaction degree were obtained at the temperature of 260 °C, which was superior to the catalytic performances of Ni/C and Co/C catalysts. A series of catalyst characterizations were conducted to reveal the mechanism of bimetallic catalysis, including BET, XRD, SEM, TEM, XPS and H2-TPD methods. Results showed that the synergistic effect between Ni and Co species was the main reason for its high catalytic activity, which resulted in a superior hydrogen transformation ability and hydrogenolysis activity. GC–MS, GPC, elemental analysis and FT-IR measurements were also used to investigate the hydrogenolysis products and the results also confirmed the superiority of bimetallic NiCo catalyst resulted from synergistic effect of Ni and Co.

Efficient liquefaction of Kraft lignin over N-doped carbon supported size-controlled MoC nanoparticles in supercritical ethanol

It is a great challenge to cleave CO bonds in lignin during liquefaction of Kraft lignin into fuels as the bond is characterized by high energy, and the complex composition of lignin oil makes it difficult to separate and purify monomers. Hence, there is an urgent need for highly selective catalysts that can help in the cleavage of these high-energy bonds. We aimed to develop effective and inexpensive catalysts for the synthesis of guaiacol compounds. Liquefaction of Kraft lignin was achieved by using a novel N-doped carbon-supported MoC nanoparticle catalyst (MoC-x@NC, x = 0.5, 1, and 1.5). 77.58 wt% of guaiacol compounds was present in 41.5 wt% of lignin oil after liquefaction of lignin. 2-phenoxy-1-phenylethanol was used as model compound to confirm the efficient CO bond-breaking properties of MoC-x@NC. Additionally, it was observed that high-valence molybdenum and metal phosphate on the surface of catalysts promoted the conversion of benzene alcohols to phenols which further enhanced the content of the guaiacol compounds. N-doped graphitic carbon substrate helps in the alkylation of guaiacol into 4-alkyl guaiacol in the presence of alkyl fragments in ethanol.