Liquefaction Solvent Research Articles

Comparative study on lignocellulose liquefaction in water, ethanol, and water/ethanol mixture: Roles of ethanol and water

This study aimed to investigate the roles of ethanol and water in the water/ethanol mixed solvent in liquefaction of lignocellulose biomass. To this end, an organosolv lignin, cellulose, cellulose/lignin (50:50, w/w) mixture and an acetone extracted white birch bark (EWBB) were comparatively liquefied in pure water, water/ethanol mixture (50:50, v/v) and pure ethanol at fixed condition (300 °C and 15 min). It was demonstrated that biomass liquefaction efficiency in three reaction media with respect to the bi-crude yield followed the order of water/ethanol mixed solvent » pure water > pure ethanol regardless of the feedstocks. Cellulose derived bio-crudes mainly contained esters, furfurals and furfurals derivatives, and carboxylic acid substantially existed in the bio-crude from cellulose liquefaction in water, while lignin derived bio-crude mainly contained aromatics, as expected. It was found that hot-compress water accelerated biomass depolymerization by hydrolyzing cellulose/hemi-cellulose, while on the other hand ethanol promoted lignin degradation by dissolving the de-polymerized lignin products and hence prevented the repolymerization of the reaction intermediates. In addition, the mixed ethanol-water solvent increased the permeation of the solvent into the lignocellulose biomass structure, and increased the solubility of liquefaction intermediates, hence contributing to a higher bio-crude yield in liquefaction of lignocellulose biomass.

Techno-economic analysis of the thermal liquefaction of sugarcane bagasse in ethanol to produce liquid fuels

A plant converting sugarcane bagasse to liquid fuels through thermal liquefaction in an Australian setting was modelled in ASPEN Plus. Ethanol was investigated as a liquefaction solvent due to its effect of higher yields and higher biocrude heating value compared to water (i.e. hydrothermal liquefaction). The plant produced 0.67 kg biocrude per kg dry feed, which was further processed to 0.46 kg liquid fuels per kg of dry feed for a total of 25.8 million L/y of biofuel product. Ethanol losses incurred the highest share in operating costs, although there are opportunities for cost reduction around lower solvent to biomass ratio. Over the plant life and with a corporate tax rate of 30%, it was determined that the minimum selling price for the fuel products is US$ 0.99/L, which was comparable to other liquefaction studies using water as solvent. It was demonstrated that continuous operation mode was economically more advantageous than semi-batch production. Product price, hydrodeoxygenation conversion efficiency and plant capacity were determined to be the factors to which NPV is most sensitive, while biocrude yield and hydrodeoxygenation conversion efficiency were the key factors in decreasing the minimum selling price of the product to a level that can be competitive.

Rational Design of Hydrogen-Donor Solvents for Direct Coal Liquefaction

Facing the challenge of processes in direct coal liquefaction (DCL), it is vital to develop optimal hydrogen-donor solvent (H-donor) to dramatically moderate coal liquefaction conditions. Here, we propose an approach for rational design of optimal H-donor candidates based on density functional theory (DFT) calculations combining reverse searching algorithm. First, the mechanism of hydrogen transfer from H-donor to coal radical was investigated by using common model compounds. DFT calculations show that the concerted hydrogen transfer route promoted by coal radicals is the dominant pathway. The C–H bond dissociation enthalpies (BDEs) show strong correlation with intrinsic reaction barriers and rate constants (in log scale), which allow us to define a cheap metric for comparing the hydrogen-donation ability of different H-donors. Then the framework for rational design of H-donor candidates is established to seek molecules with low C–H BDEs based on inverse molecular design strategy. In the searching procedu...

Unexplored Areas of Direct Solvolytic Liquefaction of Lignocellulosic Biomass

AbstractMost research on direct solvolytic liquefaction (DSL) focuses on hydrothermal liquefaction or organic model solvents and is dominated by catalytic processes. This review highlights the much less understood aspects of non‐catalytic DSL including the solvent recycling required for continuous processing. Results from earlier studies indicate both the feasibility of recycling and the non‐catalytic suppression of char formation. However, a proof of continuous operation under steady state with a stationary solvent composition and an extensive investigation of process parameters are missing to date.

Preparation and characteristics of polyurethane made with polyhydric alcohol‐liquefied rice husk

ABSTRACTThe limited availability of fossil resource is causing the urgent need to get renewable chemicals. Solvent liquefaction can convert rice husk into bio‐based chemicals. Rice husk was liquefied in polyhydric alcohol catalyzed by sulfuric acid under atmospheric pressure. The viscosity, residue content, and weight average molecular weight (Mw) of liquefied rice husk were 3089 cps, 23.6% and 4100, respectively. Prolonging the liquefaction time decreased the residue content and increased the average molecular weight. Polyurethane (PU) foams were successfully prepared from the liquefied rice husk with different molar ratios of NCO to OH (NCO/OH). The mechanical properties of PU foams showed that the compressive strength in the vertical direction is higher than that in the horizontal direction. With Increase of the NCO/OH molar ratio from 1.0 to 2.0, compressive strength in the vertical direction of PU foams increased from 70.6 to 114.7 kPa at 10% strain. Thermal analysis results showed that thermal stability of liquefied rice husk‐based PU resins was better than that of fossil‐ and liquefied wood‐ based PU resins. Increasing the NCO/OH molar ratio and inorganic residue of rice husk can help to increase thermal stability. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45910.

Continuous solvent liquefaction of biomass in a hydrocarbon solvent

Solvent liquefaction (SL) of biomass is a promising technology for the conversion of biomass to renewable fuels and chemicals. Liquid-phase thermal deconstruction of biomass in the presence of hydrocarbon-based hydrogen-donating solvents can result in bio-oils with low moisture and low oxygen content. These oils are thermally stable and highly miscible with hydrocarbon streams, which make them a promising biorenewable blendstock for petroleum refineries. We have developed a 1kghr−1 continuous SL pilot plant to evaluate the performance of SL of southern yellow pine in a hydrocarbon solvent. The process development unit (PDU) was also designed to evaluate several unit operations critical to large-scale operations. Online solids removal was conducted with inline wire mesh barrier filters with separation efficiency of over 99%. Acetone injection was used to aid in solids removal, and an online recovery system was demonstrated with greater than 97% acetone recovery. Continuous online bio-oil fractionation was also demonstrated using a distillation column to separate approximately 93wt% of the initial solvent from the biomass-derived products.

Thermal properties of biopolyol from oil palm fruit fibre (OPFF) using solvolysis liquefaction technique

Liquefaction is known to be an effective method for converting biomass into a biopolyol. The biomass liquefaction of oil palm fruit waste (PFW) in the presence of liquefaction solvent/polyhydric alcohol (PA): polyethylene glycol 400 (PEG400) using sulfuric acid as catalyst was studied. For all experiments, the liquefaction was conducted at 150°C and atmospheric pressure. The mass ratio of OPFW to liquefaction solvents used in all the experiments was, 1/3. Thermogravimetric analyses (TGA) were used to analyze their biopolyol and residue behaviors. It was found that thermal stability of oil palm mesocarp fibre (PM), oil palm shell (PS) and oil palm kernel (PK) fibre exhibited the first degradation of hard segment at (232, 104, 230°C) and the second degradation of soft segment at (314, 226, 412°C) as compared to PM, PS and PK residue which (229, 102, 227°C) of hard segment and (310, 219, 299°C) of segment, respectively. This behavior of thermal degradation of the hard segment and soft segment of biopolyol was changes after undergo solvolysis liquefaction process. The result analysis showed that the resulting biopolyol and its residue was suitable monomer for polyurethane (PU) synthesis for the production of PU foams.

Preparation of Biopolyol by Solvolysis Liquefaction of Oil Palm Mesocarp Fibre using Polyhydric Alchohol

Liquefied oil palm mesocarp fibre (LOPMF) is a promising natural material that can be used as biopolyol of polyurethane foam. The aim of this study was to utilizing solvolysis liquefaction conversion technology of oil palm mesocarp fibre (OPMF) for polyurethane (PU) foam. LOPMF was obtained with liquefaction of fibre in polyhydric alchohol (PA) such as ethylene glycol (EG), polyethylene glycol (PEG) and glycerol (GLY) as liquefaction solvent and sulphuric acid (H2SO4) in three different OPMF/PA ratio (1/2, 1/3 and 1/4) in conventional glass reactor. During the liquefaction, cellulose, semi-cellulose and lignin are decomposed, which results in changes of acid value and hydroxyl value. Liquefied OPMF and residues were characterized by Fourier transform infrared (FT-IR) spectroscopy. The results revealed that almost 50% of the OPMF converted into biopolyol product within 2 hours with OPMF/PA ratio of 1/4. Biopolyol produced under different condition showed viscosities from 210 to 450 Pa.s. The hydroxyl and acid values of the liquefied OPMF varied with the liquefied conditions. It was observed that with an increase in the liquefaction solvent (PA) amount in the mixture resulted in a high acid value and hydroxyl value for the OPMF. High reaction temperature combining with low OPMF material to solvent ratio resulted low hydroxyl number of LOPMF. The result in this study showed that biopolyol was suitable monomer for polyurethane synthesis.

Production and Characterization of Biopolyols from Crude Glycerol Based Liquefaction Process

The feasibility of using palm kernel cake and crude glycerol in liquefaction process to produce bio polyol was investigated in this study. The identiied parameters for liquefaction conditions were reaction temperature, reaction time, biomass loading and acid loading. The optimal liquefaction conditions for bio polyol production were determined to be 10%(w/w) biomass loading, 1%(w/w) acid loading, and reaction temperature at 160°C for 90min. The optimal condition yielded 83 % biomass conversion with hydroxyl and acid numbers of 552 mg KOH/g and 0.56 mg KOH/g respectively. Result shows that palm kernel cake and crude glycerol can be used as an alternative raw material and liquefaction solvent to the production of bio polyol.

Isotope analysis for understanding the hydrogen transfer mechanism in direct liquefaction of Bulianta coal

Direct coal liquefaction (DCL) was investigated using a deuterium tracer method which makes it possible to determine which structural positions in the coal react with H2 or hydrogen-donor solvents, i.e. hydrogen-transfer mechanism. D2 and/or 1,2,3,4-d4-tetralin (tetralin-d4) were used in DCL of Bulianta coal at 7.0MPa (initial charge pressure) and 445°C for 0 or 60min in a tubing-bomb microreactor. 2H NMR and isotope ratio mass spectrometry (IRMS) were used to determine the distribution of deuterium in liquefaction solvent and products qualitatively and quantitatively. The 2H NMR of solvents after DCL under a variety of conditions showed that the α-radical of tetralin is an important intermediate in hydrogen transfer to and exchange with coal, and the de/re-hydrogenation cycle of tetralin is not a dominating approach of hydrogen transfer in DCL. The distribution of deuterium in each structural position and the D/1H in preasphaltenes and asphaltenes (PAA) under a variety of conditions showed that both hydrogen atoms in tetralin and H2 could enter alkyl groups remote from aromatic nucleus of PAA in preference to aromatic nucleus and α to aromatic groups of PAA. The hydrogen atoms in tetralin are more easily to stabilize radicals from coal cracking to form PAA than those in H2 during the heating-up stage of DCL. Both the kinetic isotope effect and electrophilic aromatic substitution reaction in DCL, indicating the existence of ionic reaction process besides a radical reaction process in DCL.

Preparation of Biopolyol from Empty Fruit Bunch Saccharification Residue Using Glycerol and PEG#300-Mediated Liquefaction for Application to Bio-Polyester and Bio-Polyurethane Production

Utilization of empty fruit bunch (EFB), a by-product of the palm oil production, needs to be developed because of the expanding palm oil production scale. EFB saccharification residue was obtained as a by-product of the enzymatic preparation of sugar from EFB. The liquefaction of EFB saccharification residue was performed using a mixture of polyethylene glycol (PEG) #300 and glycerol as a solvent and sulfuric acid as a catalyst. The liquefaction conditions such as liquefaction solvent ratio, liquefaction temperature, catalyst loading, and liquefaction time were optimized, and up to 90% of biomass conversion of the EFB saccharification residue was obtained. The biopolyol with approximately 890 mg KOH/g hydroxyl number was used for the synthesis of bio-polyurethane and bio-polyester, and the polymerized products were confirmed using Fourier Transform Infrared spectroscopy analysis. Basic thermal characteristics such as glass transition temperature and thermal decomposition temperature were determined to be 93.6 and 200°C using thermogravimetric analysis and differential scanning calorimetry, respectively.

Microwave-Driven Sugar Beet Pulp Liquefaction in Polyhydric Alcohols

Abstract Liquefaction of sugar beet pulp (SBP) was carried out using microwave irradiation as the heating source, ethylene glycol/glycerol at a ratio of 80/20 (w/w) as the liquefaction solvent and sulfuric acid as the catalyst at 160 °C. The effects of different liquefaction conditions, including two particle size ranges of SBP, liquefying solvent-to-SBP solids (LS/S) ratio and reaction time on the liquefaction yield, viscosity of the liquefaction products, chemical characteristics and morphology of residues were studied using viscometry, Fourier transform infrared (FTIR), X-ray diffraction (XRD), scanning electronic microscopy (SEM). The efficiency of liquefaction of SBP was found to depend on its particle size of SBP raw material and the LS/S ratio. The smaller SBP particles improved liquefaction efficiency and reduced the amount of solvent required. The crystallinity index of liquefaction residues indicated that crystalline cellulose was no longer the rate limiting factor of liquefaction process when the particle size of SBP was small (75–177 μm). A rugged and deformed surface of the liquefaction residue (observed through SEM) indicated that severe damage in the native fiber structure occurred during the liquefaction.

Mechanism of hydrogen transfer and role of solvent during heating-up stage of direct coal liquefaction

In this paper, the liquefaction of a Bulianta coal, from China Shenhua Group, was carried out in a hydrogen donor solvent, tetralin, or a non-hydrogen donor solvent, 1-methylnaphthalene, with or without catalyst to clarify the mechanism of hydrogen transfer. And roles of solvent and a nano-size iron catalyst from Shenhua Group in the heating-up stage of DCL were also investigated by using mixed solvent of decalin, phenanthrene, pyrene or fluoranthene and tetralin. The results show that tetralin inhibits the reaction of coal macromolecule to oil and the transfer of H2. The major transfer approach of H2 may be directly from H2 to coal rather than via the hydrogen donor solvents in the presence of the nano-sized iron catalyst. In the heating-up stage of DCL, the major role of solvent is to provide activated hydrogen for coal. High dissolving capability of the liquefaction solvent that has high enough hydrogen donor capacity is beneficial for improving liquefaction performance. The dominant function of the catalyst is to promote the activation of H2, which can improve coal liquefaction performance in the heating-up stage of DCL.

Wood Liquefaction: Role of Solvent

The liquefaction of lignocellulose is strongly affected by the choice of the liquefaction solvent. This effect was studied by processing pinewood at 310 °C in various organic solvents, including some refinery streams. The impact on yields of char, biocrude, and gas was determined. The resulting biocrude was analyzed with GPC and GC-MS, the solid residue with FTIR and HR-SEM, and the gas with GC. The solvents appeared to influence the liquefaction through interaction with early carbohydrate degradation products rather than interaction with the final biocrude. Indeed, biocrude is soluble in all solvents, and char is not formed by degradation of biocrude but rather by degradation of early carbohydrate intermediates. Effective solvents show a good affinity with the biomass, e.g., as expressed by Hildebrand values of 25–40 MPa1/2 or small Hansen distances (Ra) to cellulose and lignin. Protic solvents further slowed the liquefaction reaction.

Preparation and Characterization of Biopolyol from Liquefied Oil Palm Fruit Waste: Part 2

Oil palm fruit waste (OPFW) was conducted using polyhydric alcohol (PA) as liquefaction solvent with H2SO4 in three different OPFW/PA ratio (1/2, 1/3 and 1/4). During the liquefaction, cellulose, semi-cellulose and lignin are decomposed, which results in changes of acid value and hydroxyl value. The liquefied OPFW were characterized by Fourier Transform infrared (FT-IR) spectroscopy. The hydroxyl and acid values of the liquefied oil palm fruit waste (OPFW) varied with the liquefied conditions. It was observed that with an increase in the liquefaction solvent (PA) amount in the mixture resulted in a high acid value and hydroxyl value for the OPFW. FT-IR spectroscopy analysis showed that the resulting biopolyol was suitable monomer for polyurethane (PU) synthesis for the production of PU foams.

Dynamic Dielectric Properties of a Wood Liquefaction System Using Polyethylene Glycol and Glycerol

Microwave-assisted liquefaction has shown potential for rapid thermal processing of lignocellulosic biomass. The efficiency of microwave heating depends largely on the dielectric properties of the materials being heated. The objective of this study was to investigate the dynamic interactions between microwave energy and the reaction system during the liquefaction of a woody biomass sample. The dielectric properties of poplar wood particles, model compounds representing the three main chemical components of wood, and individual liquefaction solvent components, along with their mixtures, were measured to evaluate their abilities to convert microwave energy to heat at different frequencies. Dry samples of wood particles, cellulose, xylan, and lignin were all poor microwave energy absorbers as indicated by their low dielectric values relative to the liquefaction solvent components and their mixtures; among the two solvents, polyethylene glycol had lower dielectric values than glycerol, likely due to its large...

Understanding the effect of biomass-to-solvent ratio on macroalgae (Saccharina japonica) liquefaction in supercritical ethanol

Studies on bio-oil production by thermochemical liquefaction are usually focused on the optimization of temperature, particle size, and residence time to obtain high yields, and the effects of these process parameters on biomass liquefaction are relatively well understood. However, there is a lack of agreement in previous studies on the effect of biomass-to-solvent (BS) ratio, and contradictory results have been reported. In this study, the effect of BS ratio was examined in detail using macroalgae (Saccharina japonica) as the biomass and supercritical ethanol as the liquefaction solvent at 400°C under N2 environment. The BS ratio was varied by changing the amount of either the biomass or the solvent, and the yields of the liquefaction products (i.e., bio-oil, gas, and solid residue) and the bio-oil quality were compared. When the BS ratio was increased from 0.10 to 0.17 by changing the amount of ethanol, the bio-oil yield decreased significantly from 79.5 to 37.8wt%, whereas for the same increase in BS ratio effected by changing the amount of biomass, the bio-oil yield decreased less significantly from 79.5 to 60.0wt%. This was attributed to the combined effect of BS ratio and reaction pressure on the liquefaction reaction.

Preparation of bio-polyols by liquefaction of hardwood residue and their application in the modification of polyurethane foams

Hardwood residue (HR), a byproduct of paper industry, was liquefied by using polyethylene glycol 400 (PEG400) and ethylene carbonate (EC) as the liquefaction solvents, and concentrated sulfuric acid as the catalyst to produce bio-polyols (HRLP), which were used to synthesize polyurethane (PU) foams. The effects of conditions on the properties of HRLP and modified PU foams were investigated and the mechanism of biomass liquefaction was discussed. The optimum conditions of liquefaction were obtained as follows: reaction temperature of 160 °C, reaction time of 60 min, ratio of PEG400/EC of 8:2 (w/w), and ratio of liquid/solid of 5:1 (w/w). The characterization of HRLP modified PU foams suggested that HRLP could partially replace the petroleum polyols to synthesize PU foams. With the increase of the replacement percentage of HRLP, the apparent density and compressive strength of the foams increased firstly, and then decreased. Meanwhile, the thermal stability was improved slightly.

Crude glycerol-mediated liquefaction of saccharification residues of sunflower stalks for production of lignin biopolyols

Biopolyol was produced by the liquefaction of the sunflower stalk saccharification residues using a biodiesel-derived crude glycerol as a liquefaction solvent. Biopolyol was produced under the optimal conditions of 10% (w/w) biomass loading, 4% (w/w) sulfuric acid loading at 150°C and for 60min. Biomass conversion was 59%, and the hydroxyl and acid number numbers were 1460 and 11mgKOH/g biopolyol, respectively. The bio-PU was synthesized from the biopolyol and methylene diphenyl diisocyanate (MDI). Fourier transform infrared spectroscopy (FTIR) showed that bio-PU was successfully synthesized from biopolyols and MDI.

Liquefaction of Lignocellulose in Light Cycle Oil: A Process Concept Study

Lignocellulosic biocrude can be produced by direct liquefaction of lignocellulosic biomass, which can be further upgraded into biofuels in an oil refinery. Refinery streams, namely vacuum gas oil (VGO) and light cycle oil (LCO), were found suitable liquefaction solvents in our previous study. This paper reports a process concept based on the liquefaction of wood in LCO followed by recovery and recycling of the LCO. The LCO is recovered from the reactor effluent by spontaneous liquid–liquid phase split upon cooling. The feasibility of this process concept was demonstrated experimentally by conducting a series of refill experiments with LCO recovery and recycling. This series shows a steady-state liquefaction of pine wood with constant product yields (liquid yield ∼ 57 C%) and constant oil qualities over eight recycles. Most of the ash present in the wood was concentrated in the char. A techno-economic assessment estimated that the biocrude could be produced at 13.9 $/GJ, which corresponds to an energy-equi...