Liquefaction In Ethanol Research Articles

The transformation of typical heavy metals during the process for magnetic harvesting and subsequent liquefaction in ethanol of microalgae

This study reports the transformation of three typical heavy metals (As(III), Hg(II), and Pb(II)) during the process for magnetic harvesting and subsequent liquefaction in ethanol of microalgae. The magnetic harvesting process of Chlorella Vulgaris (CV) was simulated using a co-precipitation method, achieving the highest magnetic harvesting ratio of 98.95 % at a pH of 8 and an iron-algae ratio of 0.4 g/g. Then the magnetically harvested CV was subjected to liquefaction in ethanol to explore the speciation and migration of As(III), Hg(II), and Pb(II). The environmental risk assessment of above three heavy metals in the bio-oil and biochar was assessed according to the Risk Assessment Code (RAC). Hg(II) and Pb(II) were found to be effectively stabilized and immobilized in the biochar, while As(III) exhibited a propensity to migrate into the bio-oil and existed mostly in the dangerous speciation such as fraction associated with Fe and Mn oxides and fraction bound to organic matter. It reflects a high environmental risk and necessitates a pre-removal treatment.

Effects of solvent phase recycling on microalgae liquefaction in ethanol: Bio-oil production and nitrogen transformation

Liquefaction of microalgae in ethanol offers an eco-friendly bio-oil alternative, but solvent recycling is crucial for sustainability due to extra costs. In this work, Chlorella vulgaris was liquefied in supercritical ethanol at 260 °C, and the solvent phase (SP) separated from bio-oil was recovered and reused. Five liquefaction cycles were performed at identical temperature and pressure conditions to investigate the effects on oil production and nitrogen transformation. The findings demonstrated a gradual increase in water content in recycled SP. Ethanol-water co-solvent as the reaction medium promoted the decomposition and re-polymerization of protein in raw material, thus increasing the bio-oil yield (76.84 %) and higher heating value (33.53 MJ/kg) to some extent. Simultaneously, the relative nitrogen content of bio-oil rose from 8.03 % to 8.52 %, predominantly in the form of nitrogen heterocycles. The potential pathway for nitrogen conversion was revealed, which establishes a theoretical basis for the subsequent denitrification of bio-oil.

Effect of alkali and alkaline earth metals on the liquefaction of lignocellulosic model compounds to prepare bio-oil in ethanol solvent

In this paper, glucose, xylan and lignin were selected as typical components of lignocellulosic biomass to conduct liquefaction experiments, and the effect of alkali and alkaline earth metals (AAEMs) on biomass liquefaction in ethanol was investigated. Alkaline earth metals (AEMs) had a positive catalytic effect on the yield and quality of xylan liquefied bio-oil, in particular, MgCl2 increased the yield of bio-oil from 26.6 wt% to 38.8 wt%. AAEMs inhibited the formation of glucose and lignin bio-oil, the yield of bio-oil was changed from lignin > glucose > xylan to lignin > xylan > glucose. AAEMs increased the content of ester compounds in bio-oil, inhibited the formation of long-chain aliphatic compounds, and promoted the transformation of macromolecular aromatic compounds into coke. The active catalytic sites of AAEMs were gradually covered by the adsorption of residues and carbon free radicals, blocking the active sites. The ability of carbon free radical to capture H source was weakened, and the transfer of active hydrogen to bio-oil was inhibited, which was not conducive to the improvement of higher heating value (HHV) of bio-oil.

Supercritical ethanol liquefaction of bamboo leaves using functionalized reduced graphene oxides for high quality bio-oil production

The study investigated the supercritical ethanol liquefaction of bamboo leaves using a functionalized reduced graphene oxide catalyst (GOr). The ZrO2–SrO/GOr catalyst consisted mostly of mesopores (95%) with only 5% micropores, which enhances the reactant's accessibility to active sites. The supercritical ethanol liquefaction was carried out in a 150 mL reactor and optimised for bio-oil production using an experimental central composite design (CCD). At optimum operating conditions (375 °C, a catalyst-to-biomass ratio of 1:2.5 (wt:wt) and a biomass-to-ethanol ratio of 1:10 (wt/vol), the bio-oil yield derived from bamboo leaves was 47%, which was higher than hydrothermal process (27%). A model was developed from analysis of variance (ANOVA) and validated using experimental data. The predicted and experimental data agreed well with an R2 of 0.99. The bio-oil had a higher heating value of 35.3 MJ/kg, consisting mainly of esters, phenolic and hydrocarbon compounds.

Microalgae liquefaction in ethanol to produce high-quality fuels: Effect of magnetic nanoparticles on nitrogen transformation

As the representative of the 3rd generation feedstock of biodiesel, microalgae show extraordinary advantages for energy demands. Magnetic separation is a proven and effective method for microalgae harvesting. This study aims to investigate the effect of unrecovered magnetite-based nanoparticles (Fe3O4 NPs) after microalgae harvesting on the bio-oil quality, especially nitrogen content in the subsequent production. Co-liquefaction of Chlorella Vulgaris mixed with three residual amounts (1 wt%, 5 wt%, and 10 wt% of microalgae addition) Fe3O4 NPs in ethanol at 220 and 260 °C were performed. Ethanol can provide hydrogen in situ during liquefaction, and the catalytic activity of Fe3O4 to hydrogenation reaction enhances the yield and quality of bio-oil. At 260 °C and 5 wt% NPs dosage, the bio-oil yield can reach up to 79.71%. The addition of NPs reduces the relative N content of bio-oil by more than 16.90%. GC/MS analysis shows that the nitrogen heterocyclic compounds are significantly reduced about 60%; instead, hydrocarbons are increased in the bio-oil. It implies that Fe3O4 NPs are beneficial to the denitrogenation of bio-oil during microalgae liquefaction in ethanol.

Supercritical ethanol liquefaction of rice husk to bio-fuel over modified graphene oxide

An increase in the energy system used promote new renewable source produced to improve human well-being quality. The objective of this work is to study the supercritical ethanol liquefaction reaction using rice husk as a feedstock and graphene oxide as catalyst. Characterization of the catalyst was conducted using thermal gravimetry analysis technique and N2 Sorption. Results revealed that graphene oxide treated with 1.5 M sulfuric acid solution gave the largest surface area of 110.5 m2/g. This research promised to optimize bio-fuel production using Box–Behnken method with 15 experimental data. The significant of the 3 parameters (catalyst amount, temperature and reaction time) was demonstrated using the ANOVA method. These statistical data were employed to illustrate contour data and response surface. A polynomial equation was also derived from the experimental data and used to valid with calculated data from the equation. Optimization was discussed in term of yield and operating cost. Optimum conditions were of 51.8% bio-fuel yield were derived from supercritical ethanol liquefaction at reaction time of 298 °C, 60 min reaction time, and 3.4 grams of SO4(1.5)/GO catalyst. Bio-fuel derived the optimum condition gave a high heating value as high as 30.15 MJ/kg, which is in the range of transportation fuel.

A comparison of the solvent liquefaction of lignin in ethanol and 1,4-butanediol

This study compares the depolymerization of soda lignin via solvent liquefaction in ethanol and 1,4-butanediol (BD). The commercial soda lignin was fractionated based on solubility in ethyl acetate and methanol providing three fractions (F1 – soluble in ethyl acetate and methanol, F2 - insoluble in ethyl acetate and soluble methanol, F3 – insoluble in either) which varied mostly based on their molecular weight ranges with the average molecular weight following the order F1 <F2 <F3. The whole lignin and its factions were subjected to solvent liquefaction in ethanol and BD at 300 °C, to test the use of a high boiling solvent (BD) to reduce the required reaction pressure. Use of neat BD resulted in a bio-oil similar to that produced via pyrolysis of lignin, and which had a higher average molecular weight and fewer remaining methoxy groups than those produced in ethanol. This may be attributable to differences in lignin solubility in the two solvents. The addition of formic acid was also examined in each solvent. Use of formic acid in combination with BD promoted crosslinking resulting in bio-oil with higher molecular weight. The use of lignin bio-oils from each solvent were compared as feedstocks for the production of bio-pitch, finding that those produced in BD provided a coking value closer to that required for many applications.

Influence of temperature, residence time, and solvent/feedstock mass ratio on overall product distribution and oil products quality in ethanol liquefaction of 230 polypropylene impact copolymer

This work examined liquefaction of polypropylene into liquid products in the presence of ethanol with particular attention to the effect of temperature (325–400 °C), residence time (1–6 h) and solvent/feedstock mass ratio (1/1–4/1) on the overall product distribution, and composition of the oil products. The oil products obtained under the optimal reaction condition contained mainly alkanes, alkenes, alcohols and aromatics, which accounted for 42.41%, 22.81%, 3.51%, 1.05%, respectively. Increasing temperature and retention time enhanced aromatization reaction leading to increased yields of aromatic hydrocarbons. The higher heating value of the oil product was 45.72 MJ/Kg, which is comparable to the higher heating value (HHV) of gasoline. Volatility analysis shows that 50–85 wt% of the oil composition had similar boiling point range as gasoline (35−185 °C). These characterization results suggest that the oil could be used as a raw material for gasoline blendstock or chemicals. The interaction of three reaction parameters on the oil formation was further evaluated by the response surface method. Through the Box–Behnken design, the R2, F-value and p-value of analysis of variance were 0.9917, 93.20, and < 0.0001, respectively, showed that the model fitted well with actual experimental value. It is suggested that the reaction temperature affect the oil yield more significantly, compared to other two parameters. The response surface analysis showed that under the temperature of 376.7 °C, residence time 3.8 h and solvent/feedstock mass ratio of 1/1, oil yield of 98.32 wt% can be achieved without adding catalyst or hydrogen. This predication was also verified by experiment.

Supercritical Ethanol Liquefaction of Bamboo Leaves Using Functionalized Reduced Graphene Oxides for High Quality Bio-Oil Production

Supercritical Ethanol Liquefaction of Bamboo Leaves Using Functionalized Reduced Graphene Oxides for High Quality Bio-Oil Production

Production of bio-fuel from alcohothermal liquefaction of rice straw over sulfated-graphene oxide

The objective of this research is to investigate the parameters for supercritical ethanol liquefaction of rice straw over sulfated graphene oxide. Graphene oxide was synthesized from thermal treatment of humic acid and then treated with different concentration of sulfuric acid using the wet impregnation technique. Results from liquefaction demonstrated that reaction temperature helped support the production of biofuel, but increase the formation of gas due to cracking reaction. An increase in sulfuric acid helped increase the amount of biofuel produced at first. However, as the sulfuric acid concentration increased higher than 6M, biofuel started to decrease because it is turned into gas and char products. Cracking and isomerization reactions are responsible for these products. The amount of catalyst also have an impact on the liquefaction reaction when it was increased from 5% to 10%. However, as the amount of catalyst increased further the liquefaction did not have a significant change in the ability to produce biofuel. The liquefaction reaction was optimized at 320 ºC, 6M sulfuric acid concentration and 10wt% catalyst producing 33.4% biofuel.

Enhanced production of hydrocarbons from lignin isolated from sugarcane bagasse using formic acid induced supercritical ethanol liquefaction followed by hydrodeoxygenation

This study involves the production of hydrocarbons from lignin extracted from sugarcane bagasse using Hydrothermal Liquefaction (HTL) followed by Hydrodeoxygenation (HDO). HTL of the lignin was studied under different solvents-methanol, ethanol and isopropanol in the presence of formic acid as an effective H-donor under varying lignin to solvent ratios (L:S = 1:15,1:30,1:40 g/mL), reaction temperatures (200 °C - 320 °C), reaction times (15, 30, 45,60 min) and ZnCl2 catalyst concentrations (30, 40, 50, 60 wt%). A maximum of 86% lignin derived phenolics was obtained when ethanol was used as solvent at 250 °C under L:S = 1:30 at 30 min reaction time with 60 wt% ZnCl2. The lignin-oil was upgraded by HDO process in the presence of Ni/Al2O3 catalyst and a maximum hydrocarbon yield of 73.5% was obtained with a HHV value of 48 MJ/kg. The hydrocarbons had excellent properties with a carbon range of C6–C12 with a purity of 51.2%.

Effect of solvent on hydro-solvothermal co liquefaction of sugarcane bagasse and polyethylene for bio-oil production in ethanol–water system

This study aims to investigate the role of water and ethanol in ethanol/water mixed solvent system, co-liquefaction of high-density polyethylene (HDPE) and sugarcane bagasse (SCB) to produce high quality bio-oil. It was revealed that various ethanol/water mixing ratios led to various reaction mechanisms, which indicates that there is a clear synergy effect between water and ethanol liquefaction process in three reaction media. The conversion and bio-oil yield approach were in the order of pure water < pure ethanol < water/ethanol mixed solvent regardless of the feedstock composition. Furthermore, detailed analysis of bio-oils was preformed such as CHNS/O analysis, chemical composition, 13C and 1H NMR analysis, higher heating value (HHV), TGA and FTIR analysis. The sugarcane bagasse-plastics derived bio-oil was found effective to enhance the qualitative properties of bio-oils compared from the pure sugarcane bagasse. The co-liquefaction of HDPE and SCB in mixed solvent was found more effective to enhance the qualitative and quantitative features of bio-oils compared to sole water and ethanol solvent.

Use of a Lewis acid, a Brønsted acid, and their binary mixtures for the liquefaction of lignocellulose by supercritical ethanol processing

The supercritical ethanol liquefaction of teak wood was carried out at 300 °C for 30 min without and with the use of Mg(ClO4)2, HClO4, and HClO4/Mg(ClO4)2 at various loadings (2–10 mmol).

One-step transformation of biomass to fuel precursors using a bi-functional combination of Pd/C and water tolerant Lewis acid

Direct one-pot transformation of lignocellulosic biomass has been developed as an effective and sustainable strategy to produce fuel blend stocks and high value chemical building blocks. In this wok, a bi-functional catalyst system consisting of palladium supported on carbon (Pd/C) and metal triflates (i.e., Sm(OTf)3, La(OTf)3, and Cu(OTf)2) were shown to promote the biomass liquefaction in both hot-compressed water and supercritical ethanol medium, converting fir wood into oxygenated compounds. The highest bio-oil yield from hydrothermal liquefaction (HTL) was 10.47 wt% over Pd/C whereas the highest bio-oil yield of 49.71 wt% was achieved from supercritical ethanol liquefaction (SCEL) over the bi-functional catalyst system of Pd/C and La(OTf)3. Higher heating values, carbon recovered values and boiling point distributions were further determined for elucidating the physical properties of the bio-oils. Gas chromatography mass spectrometry (GC–MS) analysis of the bio-oils revealed the chemical composition of the bio-oils. Substituted phenols and cyclopentenone/cyclopentanone type compounds consisted of more than 60 area% of the total products from HTL, whereas phenol and esters represented the major products from SCEL. The major reaction pathways are proposed based on the GC–MS results, which include depolymerizaton, isomerization, dehydration, condensation, and hydrogenation.

Production of high-quality biofuel via ethanol liquefaction of pretreated natural microalgae

The conversion of algal lipids to fatty acid alkyl esters is a promising way for the production of high-grade biofuel, due to the lower oxygen content of lipids than that of saccharides and proteins. Herein, a catalyst-free conversion process of natural microalgae cyanobacteria was developed for biodiesel production. The conversion involved two steps: (1) pretreatment of raw microalgae by Soxhlet extraction of lipids or hydrothermal treatment for extraction of saccharides and part of proteins at 200 °C; (2) liquefaction of raw and pretreated samples in sub/supercritical ethanol. In the first step, a maximum lipid yield of 6.5 wt% was extracted by Soxhlet extraction, while the hydrothermal treatment dissolved saccharides and a part of proteins. The composition of biocrude obtained from raw algae was complex, containing hydrocarbons, N-containing compounds, esters, fatty acids and other oxy-compounds. The biocrude from lipid extracted algae had a poor quality, from which the degradation of proteins was facilitated. Better yet, the extraction of saccharides and part of proteins by hydrothermal pretreatment simplified the composition (mainly fatty acid ethyl esters), reduced the nitrogen content (<4%) and improved the higher heating value (∼41 MJ kg−1) for biocrude.

Comparative investigation on bio-oil production from eucalyptus via liquefaction in subcritical water and supercritical ethanol

The present work addresses the liquefaction of eucalyptus for the production of bio-oil, examining the effects of solvent on the conversion process. The liquefaction was conducted at 260–320 °C in subcritical water and supercritical ethanol, and the bio-oil produced was analyzed by elemental components, higher heating value, GC–MS, and FTIR. Results showed that reaction medium and temperature exhibited notable influence on the process. The optimum condition for the preparation of bio-oil from eucalyptus should be conducted under water at 300 °C for 30 min, which can produce a high bio-oil yield of 30.1%. As the hydrothermal liquefaction temperature increased, the contents of aldehydes, phenols, and alkanes in the heavy oil decreased, while those of esters and ketones increased. After liquefaction in ethanol, the main substances in the heavy oil were esters, phenols, ketones, alcohols, alkanes and olefins. In light oil, esters, alcohols, phenols and ketones were the main substances. The properties of the bio-oil produced made it suitable to be applied as a promising precursor of bio-based aromatics and/or phenolic-rich antioxidant.

Cornstalk liquefaction in sub- and super-critical ethanol: Characterization of solid residue and the liquefaction mechanism

Cornstalk liquefaction in sub- and super-critical ethanol was carried out in an autoclave at various temperatures. The characteristics of solid residue were investigated by XRD and sugar analysis. Milled solid residue fraction was isolated from the solid residue, and its chemical characteristics were comparatively investigated with milled wood lignin of cornstalk by gel permeation chromatography, FT-IR, and 2D HSQC NMR. The results showed that the structure of xylan in cornstalk was not broken down completely under the reaction temperatures and those liquefaction conditions were unable to break effectively apart the inter/intra chain hydrogen bonding in cellulose fibrils. Characterization of milled solid residue showed that the de-polymerization of lignin was more dominant than the re-polymerization as reaction temperature increased from 180 to 300 °C. The β-O-4, ferulate, tricin substructures almost disappeared from the spectrum of milled solid residue, which indicated the re-polymerization or decomposition of those bonds in lignin during cornstalk liquefaction process. The result showed that characterization of solid residue fractions provided some new information of the mechanisms about cornstalk liquefaction in ethanol.

Effect of process parameters on solvolysis liquefaction of Chlorella pyrenoidosa in ethanol–water system and energy evaluation

In this work, Chlorella pyrenoidosa was converted into bio-oil via solvolysis liquefaction in sub/supercritical ethanol–water system. The influence of reaction temperature (220–300°C), retention time (0–120min), solid/liquid ratio (6.3/75–50.0/75g/mL) and ethanol content (0–100%) on bio-oil yield and property was investigated. The increase of reaction temperature and retention time both improved the bio-oil yield. The bio-oil yield increased firstly and then decreased when the solid/liquid ratio and ethanol content exceeded 18.8/75g/mL and 80%, respectively. As the reaction temperature <260°C and retention time <30min, a soft and unsticky product was insoluble in dichloromethane (DCM) during the extraction process. The chemical composition of the DCM-insoluble product was analyzed by FTIR (Fourier Transform Infrared Spectrometry). The change tendency of O/C and H/C atomic ratio of bio-oil indicated that the addition of ethanol contributed to deoxygenation and hydrogen-donating for bio-oil, due to the dehydration and decarboxylation reaction. 1H NMR (hydrogen-1 nuclear magnetic resonance) analysis indicated that the main chemical compositions of bio-oil were aliphatic functional groups and heteroatomic functionalities (80.00–83.58%). The addition of ethanol enhanced the transesterification to form more ester. The NER (net energy ratio, the ratio of energy output to energy consumption) of solvolysis liquefaction in ethanol–water system (NER<1) was less than that of hydrothermal liquefaction in sole water system (NER=1.29), but the NERs of 20% and 40% ethanol content (NER=0.91, 0.70 for 20% and 40% ethanol content) were larger than pyrolysis technology (NER=0.66). The high bio-oil yield, better bio-oil property and high NER were achieved at reaction temperature of 300°C, with retention time of 60min, solid/liquid ratio of 18.8/75g/mL and ethanol content of 40% (bio-oil yield=39.75%, HHV (higher heating value)=39.31MJ/kg and NER=0.70).

Characterization of Solid Residues Obtained from Supercritical Ethanol Liquefaction of Swine Manure

Animal wastes are considered as renewable energy resources, which contain a great energy potential. For this study, swine manure was treated with supercritical ethanol within the reaction temperature range of 240-360°C to produce bio-oil, resulting in a significant amount of solid residues. Solid residues were characterized by using Fourier Transform Infrared (FT-IR), Scanning Electron Microscopic (SEM), surface area, elemental and thermogravimetric (TG) analyses. Solid residues were mainly composed of carbon (26-29 wt%) and ash (35-45 wt%) and exhibited low surface areas (11-17 m2/g). The analyses indicated an incomplete conversion of lignocellulosic components and thermal chemical reactions including hydrolysis, dehydration, decarboxylation, aromatization and condensation. Supercritical ethanol liquefaction is considered as a feasible way to remove oxygen and utilize carbon and hydrogen in swine manure to produce carbonaceous materials and energy condensed bio-fuels.

FTIR as a simple tool to quantify unconverted lignin from chars in biomass liquefaction process: Application to SC ethanol liquefaction of pine wood

Lignin in solid residues produced from wood liquefaction can be quantified by FTIR analysis. This is applied to investigate pine wood liquefaction in supercritical ethanol in comparison with model lignin and cellulose in order to achieve a thorough description of wood liquefaction in SC ethanol. The proportions of lignin, hemicelluloses, cellulose and chars in the solid residue were quantified by compositional analysis based on acid hydrolysis combined to the quantitative FTIR analysis of the νCC vibration of lignin at 1514cm−1. It was shown that SC ethanol is an efficient medium for an easy liquefaction of lignin and hemicellulose from pine wood. Native cellulose in pine wood was only slightly attacked by contrast to microcrystalline cellulose. From pine wood, gas production is limited to 3wt.% and total yields in liquid products achieved 45wt.% but only one fourth of liquid products were eluted by GC–MS.