Liquefaction Products Research Articles

Periodic hygrothermal properties of Salix liquefaction products / isocyanate rigid foam materials

Under specific circumstances, the liquefaction product of biomass polyol can be converted into hard polyurethane foam. In this study, the rigid foam material (RPUF) was created by reacting the liquefaction product of Salix psammophila with isocyanate. The mechanical properties, chemical structure, cell structure, and thermal stability of RPUF were characterized by mechanical properties tests, Fourier transform infrared (FTIR), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The impact strength, compressive strength, and flexural strength of RPUF after hygrothermal treatment showed a downward trend. FTIR showed that the change of temperature and humidity did not affect the chemical structure of RPUF. SEM showed that the destruction of cell structure of RPUF was increased with the extension of time. TGA showed that the initial decomposition temperature of RPUF was reduced by periodic hydrothermal treatment, and the residual carbon rate decreased with the extension of treatment time.

The effect of chlorella hydrothermal products on the heavy oil upgrading process

In-situ upgrading can improve the scale of heavy oil development, but the efficiency of in-situ hydrothermal hydrogen supply is limited. In this paper, the combination of algae hydrothermal liquefaction and heavy oil upgrading and viscosity reduction process is proposed. The liquefaction products of hydrothermal liquefaction are used to supply hydrogen to the heavy oil upgrading and viscosity reduction process, thereby enriching the supply path of active hydrogen. The effects of hydrothermal liquefaction temperature of Chlorella and the addition of 5% Fe/HZSM-5 catalyst on the liquefaction rate and product distribution of Chlorella were investigated, and the upgrading and viscosity reduction process of heavy oil with the participation of hydrothermal liquefaction products was discussed. The results show that when the temperature of upgraded heavy oil is 280 °C and 5 wt% of hydrothermal liquefaction products are added and reacted for 24 h can make the viscosity reduction rate of heavy oil reach 84.32%, and 31.2% of resin in heavy oil was converted into aromatic hydrocarbon. Elemental analysis showed that the upgraded heavy oil H/C ratio increased, and GC–MS analysis showed that the distribution of algae hydrothermal liquefaction products could be adjusted by the catalyst, and more aromatics were produced after the addition of the catalyst, which confirmed that the aromatics in hydrothermal liquefaction products had a significant effect on the quality improvement and viscosity reduction of heavy oil. Its molecular weight was also found to be reduced from 853 to 326 in the average molecular weight test (GPC). The efficient carbon sequestration of algae is combined with the demand for carbon dioxide emission reduction in oilfields to realize the recycling of carbon resources.

Low-Calorie Coal Liquefaction Products as an Alternative Fuel Oil

Liquefaction of low-rank coal has been done to optimize the utilization of low-rank coal, which is less economical for obtaining alternative fuel oil. Coal samples were taken from the Bukit Pinang coal mine, Samarinda Ulu, East Kalimantan. Coal was liquefied using the NEDOL procedure at PUSPITEK, Serpong, South Tangerang, Indonesia. This Bukit Pinang coal liquefaction produces five fractions consisting of Naphta, Light Oil (LO), Middle Oil (MO), Heavy Oil (HO), and Coal Liquid Bottom (CLB) fractions. The liquefaction yield was dominated by the HO and CLB fractions (> 50% by weight). The naphtha, MO and LO fractions were fractionated using SiO2 GF254 Thin Layer Chromatography (TLC) plate. It produced aliphatic and aromatic hydrocarbon fractions. Aliphatic hydrocarbon fractions were analyzed using a Gas Chromatography-Mass Spectrometer (GC-MS), while the aromatic hydrocarbon fractions were not analyzed. Mass spectrum studies showed that the components consisted of n-alkanes, isoalkanes (branched alkanes), cycloalkanes and alkyl cycloalkanes. The aliphatic hydrocarbon components resulting from the liquefaction of low-rank coal showed its equivalence with the components that make up fuel oil. Therefore, this coal liquefaction can be suggested as an optimization for low-rank coal, which is less economical.

Study on oxygen species in the products of co-liquefaction of coal and petroleum residues

From the view of atom economy, it is important to know the form and apportion of oxygen in products, especially the apportion of oxygen in CO2 during direct coal liquefaction (DCL) and co-liquefaction of coal and petroleum residues (CCPR). Herein, co-liquefaction of Naomaohu lignite with Tahe petroleum residue (THPR) was conducted and the O distribution in liquefaction products including gas, n-hexane soluble (HS), asphaltene and pre-asphaltene (AP), and residue (Res) were analyzed by elemental analyzer, GC, GC-MS, FT-IR and APCI-MS. The results showed that CCPR did not change the oxygen speciation but the O distribution in products. O-containing radicals generated from coal pyrolysis would bind to the alkyl radicals from petroleum residue decomposition during CCPR, resulting in remarked increase in the content of O-containing alkanes. Compared with DCL, the apportion of organic oxygen (HS and AP) was increased by 25.94% during CCPR, and the inorganic oxygen (CO, CO2, H2O, and Res) was decreased by 7.10%, wherein, CO2 content in inorganic oxygen was reduced by 2.13%. This implies that the CCPR not only significantly enhances the utilization of organic oxygen in coal but also inhibits CO2 generation, which is vital for realizing the goal of carbon peak and neutrality.

Transition metal load HZSM-5 catalyst assisted hydrothermal conversion of sewage sludge: Nitrogen transformation mechanism and denitrification effectiveness ofbio-oil

Sewage sludge is not only a kind of hazardous waste, but also biomass resources that rich in organic matter. Hydrothermal liquefaction (HTL) is an effective way of converting sewage sludge (SS) into fuels and chemicals. In this study, the HTL of SS was performed with the aid of transition metal supported HZSM-5 catalyst at 340 °C, conducted with methanol-water as the solvent. The existing forms of nitrogen in the full-component products were tested and analyzed, and the possible migration and transformation paths of nitrogen in the catalytic liquefaction process were proposed. The addition of catalyst has an effect on the physicochemical properties and yield of the liquefaction products. The highest bio-oil yield (28.55%, 26.16%) was achieved at 340 °C with the inclusion of 0.5%Co/HZSM-5 and 1%Ni/HZSM-5, which improved the bio-oil yield by 30% compared with the non-catalyzed group. Ni and Co modified HZSM-5 showed a similar trend of nitrogen transfer, the bio-oil obtained by using metal-loaded HZSM-5 catalysts has higher hydrogen content and lower nitrogen and oxygen content. Catalytic-liquefaction promoted the distribution of nitrogen to solid residues and aqueous. Furthermore, the addition of catalyst promoted the ring opening reaction of the polycyclic compounds and the conversion of the polycyclic nitrogen compounds to amines and amides. The content of monocyclic nitrogen compounds in bio-oil increased while polycyclic nitrogen compounds decreased.

Relevance between Cassava Starch Liquefied by Phenol and Modification of Phenol-Formaldehyde Resin Wood Adhesive.

A novel type of phenol-formaldehyde (PF) resin was prepared by utilizing the liquefaction products liquefied by phenol under acidic conditions and then reacted with formaldehyde under alkaline conditions. The relationship between the liquefaction behavior of cassava starch and the properties of modified PF resin wood adhesive was studied. The effects of the liquid–solid ratio of phenol to cassava starch, sulfuric acid usage, and liquefaction time on the liquefaction residue rate and relative crystallinity of cassava starch were determined. The results showed that the bonding strength of modified PF resin decreased gradually with the decrease of the liquid–solid ratio. It was a great surprise that bonding strength still met the requirement of the national standard of 0.7 MPa when the liquid–solid ratio was 1.0. The detailed contents were analyzed through FT-IR, SEM, and XRD. In terms of the utilization of bio-materials for liquefaction to synthesize wood adhesive, cassava starch may be superior to the others.

Machine learning predicts and optimizes hydrothermal liquefaction of biomass

The hydrothermal liquefaction process has recently attracted more attention in biorefinery design and implementation because of its capability of handling various wet biomass feedstocks. However, measuring the quantitative and qualitative characteristics of hydrothermal liquefaction (by)products is challenging because of the need for time-consuming and cost-intensive experiments. Machine learning technology can cope with this issue thanks to its ability to learn from past datasets and mechanisms. Hence, machine learning was applied herein to quantitatively and qualitatively characterize hydrothermal liquefaction (by)products based on biomass composition and reaction conditions. The data patterns compiled from the published literature were used to develop a universal machine learning model applicable to a wide range of biomass feedstocks and reaction conditions. The collected data were statistically analyzed and mechanistically discussed. Among the four machine learning models considered, Gaussian process regression could provide the highest accuracy, with a correlation coefficient higher than 0.926 and a mean absolute error lower than 0.031. An effort was also made to maximize biocrude oil quantity and quality and minimize byproducts quantity using the objective functions developed by the selected model. The optimal biocrude oil yield (48.7–53.5%) was obtained when the carbon, hydrogen, nitrogen, oxygen, sulfur, and ash contents of biomass were in the range of 40.9–48.3%, 9.72–9.80%, 11.9–13.6%, 15.2–15.6%, 0.0–0.94%, and 0.0–2.92%, respectively. The optimal operating conditions were: operating dry matter = 31.4–33.0%, temperature = 394–400 °C, reaction time = 5–9 min, and pressure = 30.0–35.6 MPa. An easy-to-use software package was developed based on the selected machine learning model to pave the way for bypassing unnecessary lengthy and costly experiments without requiring extensive machine learning knowledge. The present study highlights the vast potential of machine learning for modeling biomass hydrothermal liquefaction.

Thermochemical liquefaction of wheat straw in sub- and supercritical tetralin

The present work investigates the thermochemical conversion of wheat straw biomass in a suband supercritical tetralin medium. The experiment was carried out in a batch reactor at 285, 330, 380, 420 and 460 °C for 10 minutes. The process of straw liquefaction in subcritical tetralin was characterised by relatively high efficiency. At 420 °C, the biomass conversion rate amounted to 98.2% a.d.m. The maximum yield of liquid products during liquefaction (81.6% a.d.m.) was obtained at 380 °C. The liquid products were fractionated by successive extraction with hexane, water and ethanol. According to GC-MS data, the liquefaction products soluble in hexane comprised a mixture of low-molecular weight degradation products of straw components and tetralin derivatives, including methyl esters of fatty acids, aromatic compounds, alkanes and minor alcohols and ketones. When the process temperature increased, the content of esters diminished, followed by an increment in the proportion of aromatic compounds up to 50% rel. No esters and phenolic compounds were present in the liquefaction products soluble in hexane obtained at 460 °C. Dehydrogenation, alkylation and isomerisation of tetralin with the formation of naphthalene, 1,4-dihydronaphthalene and alkyl derivatives of tetralin, naphthalene and indane occurred under the given conditions. The conducted comparative analysis of infrared spectra for straw and solid products of liquefaction suggested that, at temperatures of up to 330 °C, the process of polysaccharide fragmentation is more pronounced in the straw biomass, while, at higher temperatures, the process of lignin fragmentation prevails. As a result, the IR-spectrum of the solid product obtained at 380 °C revealed weakly pronounced absorption bands of alkylaromatic structural fragments. At the same time, only the absorption bands of mineral components in straw ash and adsorbed water were observed in the IR-spectrum of the solid product obtained at 420 °C.

Instant catapult steam explosion pretreatment of wheat straw liquefied polyols to prolong the slow-release longevity of bio-based polyurethane-coated fertilizers

The direct liquefaction product of crop straws for bio-based polyurethane-coated fertilizers (BPCFs) has low hydroxyl values and complicated composition types, resulting in poor crosslinking degree, high hydrophilicity, and short release longevity. This study created an efficient physicochemical instant catapult steam explosion pretreatment wheat straw (SEWS) technology to remove small molecular hemicellulose and difficult-to-film-forming ions, improve straw liquefied polyol quality, and extend the release longevity of BPCFs. The results revealed that the steam explosion process (2.0 MPa for 5 min) broken the straw cell wall, hydrolyzed hemicellulose, and significantly decreased the difficult-to-film-forming ions (K+, Ca2+, and Mg2+). The SEWS liquefied residue rate dropped 38.1% to 5.5%, while the hydroxyl value increased 36.51% to 125.32 mg KOH g−1. The liquid polyol of SEWS and diphenyl-methane-diisocyanate formed a tightly cross-linked, homogenous bio-based membrane with no visible holes. Under the condition of 3% weight of the core fertilizer, the release longevity of SEWS increased from 14 to 32 days. The use of instant catapult steam explosion technology for high-efficiency pretreatment of biomass materials is conducive to improving the quality of bio-based polyols and the industrial production of bio-based controlled-release fertilizers. Furthermore, the pretreatment technology promotes the use of biomass for sustainable agriculture.

The Effect of Dichloromethane on Product Separation during Continuous Hydrothermal Liquefaction of Chlorella vulgaris and Aqueous Product Recycling for Algae Cultivation

Dichloromethane (DCM) is a solvent commonly used in laboratories for microalgae hydrothermal liquefaction (HTL) product separation. The addition of DCM would lead to an “overestimation effect” of biocrude yield and diminish biocrude quality. However, it is currently not clear to what extent this overestimation effect will impact a continuous HTL process. In this study, Chlorella vulgaris microalgae was processed in a continuous stirred tank reactor at different temperatures (300, 325, 350, 375, and 400 °C) at 24 MPa for 15 min holding time. Two separation methods were applied to investigate the effect of using DCM in a cHTL product separation procedure in terms of product yield, biocrude elemental content, and aqueous product (AP) composition. Subsequently, the feasibility of reusing AP for algae cultivation has been evaluated. Results suggest that 350 °C is the optimal temperature for cHTL operation, leading to the highest biocrude yield, and an average increase in biocrude yield of 9 wt % was achieved when using DCM in cHTL product separation. Within the temperature range investigated, an average biocrude yield estimation can be proposed by yieldnon-DCM ≈ 0.818 × yieldDCM. The AP has been characterized by total organic carbon and total nitrogen, high-performance liquid chromatography, and inductively coupled plasma optical emission spectroscopy. Results show that at 350–375 °C more nitrogen and other ions were directed into the AP, which could be advantageous in nutrient recovery. With the help of optical density testing, algae was shown to exhibit a better growth using AP with activated carbon absorption purification treatment as compared to the standard medium. The recovery of water and nutrients from the HTL-AP could improve the economics of a microalgae biorefinery process.

Study on Oxygen Speciation in the Products of Direct Coal Liquefaction and Co-Liquefaction of Coal and Petroleum Residues

Study on Oxygen Speciation in the Products of Direct Coal Liquefaction and Co-Liquefaction of Coal and Petroleum Residues

Investigation of the liquefaction possibility of Ermenek lignite as an alternative clean energy source

Coal liquefaction; can be defined as the transformation of coal into products that have a high energy density, can be easily stored and transported and do not create environmental pollution, to meet both fuel and chemical raw material requirements.
 This study was carried out to determine the yields of the products formed as a result of the liquefaction of Konya-Ermenek lignite in the N2 atmosphere and under non-catalytic conditions. Proximate and ultimate analysis of the obtained solid and liquid products was made. The composition of the oil product was determined by GC-MS. As a result of liquefaction, the char yield was 71.37%, the preasphaltene yield was 12.24%, the asphaltene yield was 2.23% and the oil + gas yield was 14.16%. It was determined that the higher heating value of 4199 kcal/kg in raw lignite is twice as high in liquefaction products. It was determined that the sulfur content of 3.94% in raw lignite decreased to 1.54%, 0.85% and 0.44% in char, preasphaltene and oil, respectively.

Potential Use of Plant Biomass from Treatment Wetland Systems for Producing Biofuels through a Biocrude Green-Biorefining Platform

The potential of using the biomass of four wetland plant species (Iris pseudacorus, Juncus effusus, Phragmites australis and Typha latifolia) grown in treatment wetland systems and under natural conditions were tested to produce high-value materials using hydro-thermal liquefaction (HTL). The results show that the wetland plants biomass is suitable for biocrude and biochar production regardless of the origin. The hydrothermal liquefaction products’ (biocrude, biochar, aqueous and gaseous phase) yields vary according with the specific biomass composition of the species. Furthermore, the results show that the biomass composition can be affected by the growing condition (treatment wetland or natural unpolluted conditions) of the plants. None of the single components seems to have a determinant effect on the biocrude yields, which reached around 30% for all the analyzed plants. On the contrary, the biochar yields seem to be affected by the composition of the biomass, obtaining different yields for the different plant species, with biochar yields values from around 12% to 22%, being that Phragmites australis is the one with the highest average yield. The obtained aqueous phase from the different plant species produces homogeneous compounds for each plant species and each growing environment. The study shows that biomass from treatment wetlands is suitable for biocrude production. The environmental value of this biomass lies on the fact that it is considered a residual product with no aggregated value. The treatment wetland biomass is a potential sustainable source for biofuel production since these plants do not need extra land or nutrients for growing, and the biomass does not compete with other uses, offering new sources for enhancing the bioeconomy concepts.

Polyvinyl alcohol based bio‐composite films reinforced by liquefaction products and cellulose nanofibrils from coconut coir

AbstractIn this study, coconut coir was chemically converted to coir‐polyols (CP) via atmospheric liquefaction under microwave assistance, during which a combination of polyethylene glycol 400 and glycerol, and 98% sulfuric acid were applied as the liquefaction solvents and catalyst, respectively. The obtained CP was then analyzed in terms of its molecular weight distribution, hydroxyl values, and functional groups. Later, CP/polyvinyl alcohol (PVA) bio‐composite films reinforced without and with coir cellulose nanofibrils (CCNF) were prepared. After comprehensive characterization, the CP/PVA films exhibited higher stability in medium‐temperature range, while the CCNF/CP/PVA films on the other hand possessed higher properties of tensile strength, elongation at break, and water resistance. The proper dosage of reinforcing agents for preparing PVA‐based ternary blend films were proposed at 3% of CCNF and 10% of CP (based on film dry weight), which exhibited the best balance of properties in the critical parameters such as tensile strength and elongation at break.

Investigation of the improvement of Sivas-Kangal lignites liquefaction product yields

In recent years, converting and using coal into the most suitable product according to its properties has emerged as a modern approach. Among the main processes applied to coal are low and high-temperature carbonization, gasification and liquefaction. In coal liquefaction, coal is broken down into free radicals using hydrogen donor solvent and catalyst under high temperature and pressure conditions. Later, these radicals can be used in the production of both liquid fuel and chemical raw materials by being saturated with hydrogen. This study aims to improve the yields of Sivas-Kangal lignite liquefaction products (char, preasphaltene, asphaltene, oil-gas). For this purpose, firstly raw coal, then spiral enriched clean coal liquefaction experiments were carried out. The chemical characterizations of the obtained products were determined by proximate and ultimate analysis. The composition of the oil was identified by GC-MS. As a result of the enrichment, the char yield decreased by 16.5% whereas the oil+gas yield increased by 14.64%. Total conversion increased from 31.74% to 48.24%. It has been concluded that the enrichment process has a positive effect on the liquefaction yields.

High-Strength and Low-Cost Biobased Polyurethane Foam Composites Enhanced by Poplar Wood Powder Liquefaction.

An environmentally friendly liquefaction of wood powder was prepared by atmospheric pressure liquefaction technology to replace the non-renewable petroleum polyols in the preparation of polyurethane foam composites. The liquefaction time varied from 0 min to 140 min. The composition of liquefied products and the effects of liquefaction time on the morphology, apparent density and mechanical properties of polyurethane foam composites were investigated. The results showed that the optimal process time for the preparation of wood powder liquefaction products, which could replace traditional petroleum polyols, was 110 min. At this time, polyether polyols are the main liquefaction products, with an average molecular weight in Mn reaching 237 and average molecular weight in Mw reaching 246. The functional group of the liquefied product consisted mainly of hydroxyl, with the highest content of 1042 mg KOH/g and the lowest acid number of 1.6 mg KOH/g. In addition, the surface of the polyurethane foam based on poplar wood is dominated by closed cell foam; thus its foam has good heat insulation and heat preservation properties. At 110 min liquefaction time, the apparent density of polyurethane foam is 0.164 g/cm3 and the compression strength is 850 kPa, which is higher than that of traditional polyurethane foam (768 kPa), which is without wood powder modification. Replacing petroleum polyol with renewable wood powder liquefaction products to prepare biomass-based polyurethane foam composite materials, researching complex chemical changes in different liquefaction stages, and finding the best liquefaction conditions are of great significance to optimize the performance of polyurethane, address the shortage of resources and reduce environmental pollution.

Study on the transformation characteristic of heteroatoms during liquefaction of Naomaohu coal

In this work, Naomaohu coal was used for direct liquefaction. The conversion and oil yield as a function of hydrogenating temperature were investigated, and the transformation characteristics of heteroatoms in raw coal and liquefaction products were clarified. The results showed that Naomaohu coal presented high liquefaction performance even under lower initial pressure of 2 MPa. The conversion and oil yield could reach 69.6% and 55.3%, respectively, at a pressure of 2 MPa and 400°C. Gas chromatography-mass spectrometry and gas chromatography-atomic emission spectrometry were combined to analyze the products. It was found that the weak bond structure containing heteroatoms was easier hydrogenated to fracture and removed in the form of H2S, NH3, H2O, etc. The sulfur-containing compounds in liquefied products were mainly thiophene and thiophene homologues. The content of nitrogen-containing compounds was trace and mainly consisted of nitrogen heterocyclic compounds. The oxygen-containing compounds in liquefied oil were dominantly phenols and their homologues. The heteroatoms in the aromatic structure would generate more stable heteroatom-containing compounds in the liquefaction residue via the free radical polycondensation reaction.

Influence of soaking temperature time on the ability prepared liquefaction of wood from cashew nut shell waste

Liquefied wood is one of the phenolic resin. However, unlike commercial phenolic resins that are normally synthesized by the chemical reaction between phenol and formaldehyde, liquefied wood is usually produced by reacting phenol with wood-derived materials, and catalyst at 120-180◦C. Depending on whether the catalyst is a base or a acid, the formed resin is a thermoset or a thermoplastic. In this study, wood liquefaction was prepared from a cashew nut shell waste (CNSW), phenol, and sulfuric acid catalyst. The cashew nut shell waste is taken from Binh Phuoc province - Vietnam and crushed to a size of less than 500 mm. Phenol and sulfuric acid catalyst are chemical experiments. The powder of cashew nut shell waste, phenol, and sulfuric acid were mixed and reacted at 150oC for different soaking times. An optimal soaking temperature time was determined through a cashew nut shell waste residue content in wood liquefaction products. The wood liquefaction products also were determined by a number average molecular weight (Mn) and a weight average molecular weight (Mw) by Gel permeation chromatography method (GPC); the function groups by Fourier Transform Infrared method (FT-IR). The results showed that the formed resin is thermoplastic and the optimal soaking time to prepared liquefied wood is 180 minutes. This sample has a residual cashew nut shell waste ratio of 9.44%, a number average molecular weight of 7552, and a weight average molecular weight of 10640. The liquefied wood from cashew nut shell waste can be used as a binder in the manufacture of the medium density fiberboard (MDF) or as a material to promote the sintered process in the production of woodceramic materials. In addition, the liquefied wood can also be pyrolyzed to form carbon fiber. Carbon fiber can be applied as reinforcing materials for ceramic products.

Fine structure impacts highly concentrated starch liquefaction process and product performance

Designing a highly concentrated (45 %, w/w) starch liquefaction process is a green method to enhance the productivity of starch syrup and related fermentation products. Previous studies mainly focused on handling highly concentrated normal corn starch slurries, but the production efficiency and product performance cannot perfectly match the conventional liquefaction process (30 %, w/w). In the present research, four starches from various botanical sources were selected with an objective to accelerate highly concentrated starch liquefaction process. The results demonstrated that with potato starch or tapioca starch as a substrate, liquefaction process was more feasible as observed from the obvious reduction in paste viscosity and acceleration in amylolysis. To clarify the mechanism of these differences, changes in the fine structure during liquefaction were further characterized. The long external chains (16.2 glucose units on average) in potato starch and long internal chains (5.1 glucose units on average) in tapioca starch, which indicated high proportion of consecutive α-1,4 linkages, seemed more susceptible to enzymatic attack under highly concentrated substrate condition. This caused rapid degradation of starch molecules. The liquefied products were suitable for glucose syrup production. By comparison, normal corn starch and waxy corn starch, which contain relatively shorter linear fragments, were less accessible to α-amylase. This suppressed liquefaction process led to the survival of large molecules, thereby being unsuitable for subsequent saccharification process. The results suggest that selecting an appropriate substrate is an effective strategy to accelerate highly concentrated starch liquefaction and improve product performance.

Microwave-assisted lignin liquefaction in hydrazine and ethylene glycol: Reaction pathways via response surface methodology

Microwave assisted liquefaction (MAL) of alkali lignin in ethylene glycol (EG) in the presence of hydrazine was carried out using response surface methodology. Dielectric properties of mixtures of lignin/EG at different hydrazine concentrations were determined to enhance the understanding of the MAL process. MAL parameters were hydrazine concentration (1–3%), temperature (100-180 °C), time (5-45 min) with the maximum microwave heating power limited to 750 W. Lignin/EG ratio was fixed at 1 g:10 ml. Dielectric properties were significantly influenced by hydrazine concentration and temperature. Major products from the liquefaction process (as % of peak areas) were grouped into guaiacol and derivatives (17–42%), Nitrogen compounds (0–27%), and Hydroxylated products (8–22%), and their yields were modelled with polynomial equations. Product yields were significantly influenced by process parameters. Optimum parameters for maximizing yields of guaiacol and nitrogen containing compounds were 0.5%, 180 °C, 25 min and 2.5%, 130, 25 min for hydrazine concentration, temperature, and time, respectively. Low hydrazine concentration increases guaiacol yield at higher temperatures, indicating that at high temperatures hydrazine behaves as a hydrogen donor for lignin liquefaction. The yield of nitrogen containing compounds increases at relatively low temperatures and high concentration of hydrazine. Apart from playing the respective roles of liquefaction solvent and hydrogen donor, EG and hydrazine also take part in the reaction thereby significantly modifying the composition of reaction products. A mechanistic reaction mechanism was proposed to explain the formation of the liquefaction products.