A new role of supercritical ethanol in macroalgae liquefaction (<i>Saccharina japonica</i>): Understanding ethanol participation, yield, and energy efficiency

Zeb, Hassan,Choi, Jaeyeon,Kim, Yunje,Kim, Jaehoon Elsevier 2017 ENERGY Vol.118 No.-

<P><B>Abstract</B></P> <P>Liquefaction of macroalgae was performed in a stirred autoclave reactor using supercritical ethanol (scEtOH) as a solvent. There was a sharp transition in ethanol consumption during macroalgae liquefaction in scEtOH when the temperature was increased from 350 to 400 °C. At 350 °C, a small amount of ethanol (6 wt%) reacted with intermediates, while at 400 °C, 18 wt% of the ethanol was consumed. Taking into account this increased consumption of ethanol at 400 °C, the bio-oil yield decreased from 79.2 to 53.9 wt%, energy recovery from 202.5% to 72.2%, and energy efficiency from 111.6% to 62.7%. The produced bio-oil had a molecular weight of 398 g mol<SUP>−1</SUP>, a HHV of 36.49 MJ kg<SUP>−1</SUP>, an O/C ratio of 0.12, and a H/C ratio of 1.58. To confirm the unique role of scEtOH in biomass liquefaction, subcritical water (subH<SUB>2</SUB>O) and supercritical water (scH<SUB>2</SUB>O)-based liquefactions were carried out and the results compared with those obtained for scEtOH-based liquefaction. GC-MS results from the bio-oil produced with scH<SUB>2</SUB>O revealed the percentage area of compounds containing an ethoxy group to be as low as 20%, while this value reached 62% when using scEtOH.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Supercritical ethanol not only acts as a solvent but also as a reagent. </LI> <LI> Ethanol consumption during reaction was calculated by GC-MS ethanol calibration. </LI> <LI> Bio-oil yield, ER and EE were re-calculated considering consumed amount of ethanol. </LI> <LI> Decrease in bio-oil yield, ER and EE when consumed ethanol was taken into account. </LI> </UL> </P>

Liquefaction of major lignocellulosic biomass constituents in supercritical ethanol

Brand, Steffen,Kim, Jaehoon Elsevier 2015 ENERGY Vol.80 No.-

<P><B>Abstract</B></P> <P>Herein, α-cellulose, <SMALL>D</SMALL>-xylose, and lignin, which are major lignocellulosic biomass constituents, are subject to being liquefied in scEtOH (supercritical ethanol). Biomass conversion, biocrude yield, gas composition and energy content resulting from the liquefaction are analyzed. When cellulose is used, the biocrude yield increased significantly from 1.6 to 48.4 wt% with an increase in temperature from 265 to 350 °C, while the yields of biocrudes obtained from lignin (25.2–28.8 wt%) and xylose (32.1–42.0 wt%) do not change significantly with varying temperature. The chemical composition of the biocrudes obtained from the cellulose and xylose liquefaction in scEtOH significantly differ when compared to those of the biocrudes obtained from fast pyrolysis and hydrothermal liquefaction. The unique chemical species in the scEtOH-liquefied biocrude include long-chain esters/ethers (C5–C10), long-chain acids (C4–C9), and tetrahydrofurans, which could be due to the enhanced esterification and hydrogenation reactions in the scEtOH medium. Plausible reaction pathways of xylose liquefaction in scEtOH are proposed.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Cellulose, hydrolysis lignin, xylose are liquefied in supercritical ethanol. </LI> <LI> Increase in biocrude yield when cellulose is used. </LI> <LI> Biocrude yields are similar with temperature when lignin and xylose are used. </LI> <LI> Long-chain esters/ethers/acids (C5–C10) and tetrahydrofurans form. </LI> <LI> Esterification and hydrogenation are enhanced in supercritical ethanol. </LI> </UL> </P>

Enhancement of Supercritical CO2 Inactivation of Spores of Penicillium oxalicum by Ethanol Cosolvent

( Hyong Seok Park ),( Kyoung Heon Kim ) 한국미생물 · 생명공학회 2013 Journal of microbiology and biotechnology Vol.23 No.6

The inactivation of spores of Penicillium oxalicum by supercritical carbon dioxide (SC-CO2) was optimized by response surface methodology. The optimal inactivation conditions of 16.8 MPa, 49℃, and 20 min were determined using ridge analysis, at which the predicted and experimental log10 reductions were obtained as 5.74 and 6.12, respectively. The synergistic effect of a cosolvent (ethanol), which was used to modify SC-CO2, on the inactivation of the fungal spores was investigated. At less severe conditions of 10 MPa and 40℃, P. oxalicum spores of 107 CFU/ml were completely inactivated within 45 min by SC-CO2 modified with ethanol.

1P-469 Catalytic depolymerization of lignin over transition metal supported ZSM-5 in supercritical ethanol

양승도,정소연,김도희 한국공업화학회 2017 한국공업화학회 연구논문 초록집 Vol.2017 No.1

The depolymerization of Protobind lignin into monoaromatic compounds was conducted with a batch reactor over transition metals supported on ZSM-5 catalysts in supercritical ethanol supplying in-situ hydrogen. It was observed that the trend of yields according to the amount of transition metal loading formed the volcano shape curve and had the linear correlation between yield of monoaromatic compounds and acid density. In addition, it was found that Cu metal among transition metals plays an important role in promoting the depolymerization of lignin. Cu/ZSM-5, which was loaded 10 wt.% Cu and was Si/Al₂ ratio of 30, resulted in the highest yield of monoaromatic compounds; 98.2 wt%. Meanwhile, HSQC NMR analysis provided the evidence about the promotion of the depolymerization of Protobind lignin by hydrogenolysis and the alkylation of monoaromatic compounds by ethanol.

Excellent aging stability of upgraded fast pyrolysis bio-oil in supercritical ethanol

Jo, Heuntae,Verma, Deepak,Kim, Jaehoon Elsevier 2018 Fuel Vol.232 No.-

<P><B>Abstract</B></P> <P>The stabilities of low-boiling-fraction fast pyrolysis bio-oil (LBFBO) and upgraded bio-oil (UBO) produced using supercritical ethanol (scEtOH) were examined under accelerated aging conditions at 80 °C for up to 1 year. During the 3-month aging of LBFBO, a jelly-like non-flowable phase formed, and a hard, solid block formed after further aging for over 6 months. The viscosities and molecular weights of aged LBFBOs increased significantly. In contrast, the UBOs exhibited excellent stabilities after up to 6 months of aging with marginal increases in their viscosities and molecular weights. The condensation reaction during the aging of LBFBO led to the formation of water and reduced the oxygen content, while negligible changes were observed in the elemental contents of the aged UBOs. The excellent aging stability of UBO was attributed to its non- or less-reactive chemical species than those of LBFBO. Acetic acid, which acted as a catalyst for condensation and persisted for the 3-month aging of LBFBO, was converted into its corresponding ethyl ester during the scEtOH upgrading. The reactive pyrolytic lignin in LBFBO decomposed into its low-molecular-weight fractions. In addition, the other reactive species in LBFBO, such as aldehydes, furfural, and monoaromatics substituted with α,β-unsaturated aldehyde groups, were converted to less- or non-reactive species during the upgrading. Therefore, negligible compositional changes in the chemical structure of UBOs were achieved for up to 6 months of aging.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Accelerated aging for 1 year was tested before and after supercritical upgrading. </LI> <LI> Fast pyrolysis bio-oil (LBFBO) was upgraded in supercritical ethanol. </LI> <LI> Upgraded bio-oil (UBO) consisted of esters, alcohols, ethers and alkylated phenols. </LI> <LI> During the 3-month aging of LBFBO, a jelly-like non-flowable phase formed. </LI> <LI> Negligible compositional changes of UBO were achieved for up to 6 months of aging. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Effective depolymerization of concentrated acid hydrolysis lignin using a carbon-supported ruthenium catalyst in ethanol/formic acid media

Kristianto, Ivan,Limarta, Susan Olivia,Lee, Hyunjoo,Ha, Jeong-Myeong,Suh, Dong Jin,Jae, Jungho Elsevier 2017 Bioresource technology Vol.234 No.-

<P><B>Abstract</B></P> <P>Lignin isolated by two-step concentrated acid hydrolysis of empty fruit bunch (EFB) was effectively depolymerized into a high-quality bio-oil using formic acid (FA) as an <I>in-situ</I> hydrogen source and Ru/C as a catalyst in supercritical ethanol. A bio-oil yield of 66.3wt% with an average molecular weight of 822g/mol and an aromatic monomer content of 6.1wt% was achieved at 350°C and a FA-to-lignin mass ratio of 3 after a reaction time of 60min. The combination of Ru/C and FA also resulted in a significant reduction in the oxygen content of the bio-oil by ∼60% and a corresponding increase in the higher heating value (HHV) to 32.7MJ/kg due to the enhanced hydrodeoxygenation activity. An examination of the FA decomposition characteristics revealed that Ru/C provides a greater increase in the rate of hydrogen production from FA, explaining the efficient depolymerization of lignin in a combined system.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The depolymerization of concentrated acid hydrolysis lignin (CAHL) is studied. </LI> <LI> Solvothermolysis of CAHL in ethanol results in a low depolymerization efficiency. </LI> <LI> The addition of Ru/C and FA improves the extent of depolymerization significantly. </LI> <LI> The dehydrogenation of formic acid is significantly enhanced with the use of Ru/C. </LI> <LI> The process achieves a high bio-oil yield of ∼70wt% and HHV of 32.7MJ/kg. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Evaluation of Solubility of Ethanol, 2-propanol in Supercritical Carbon Dioxide for the Application of Soil Decontamination Process

Seungil Ha,Kwangheon Park,Jinhyun Sung 한국방사성폐기물학회 2022 한국방사성폐기물학회 학술논문요약집 Vol.20 No.2

Radioactive contamination of soil on the site of a nuclear facility has a characteristic that radioactive nuclides are adsorbed into the pores between soil particles, making it quite difficult to decontaminate. For this reason, research on the development of various decontamination processes is being actively conducted. In this study, among various decontamination studies, a soil decontamination process using supercritical carbon dioxide was presented. The decontamination process uses supercritical carbon dioxide as the main solvent, which has a higher penetration power than other materials. Therefore, the process consists of the process of desorbing and extracting the target radionuclides between particles of soil. However, since nuclides exist as ions in the soil, polar chelating ligand material was introduced as an additive to nonpolar supercritical carbon dioxide for smooth chemical reactions in the soil. Thereafter, from the viewpoint of improving process continuity and efficiency, an alcohol material was introduced as an auxiliary solvent for liquefaction of chelating ligand in a solid state. Through prior research on the selection of a solvent for liquefaction of chelating ligand, ethanol and 2-propanol were finally selected based on whether the chelating ligand was dissolved. However, if the auxiliary solvent in which the chelating ligand is dissolved is to be combined with radionuclides in the soil, it must first be well dissolved in supercritical carbon dioxide, the main solvent. Therefore, in this study, the solubility of ethanol and 2-propanol in supercritical carbon dioxide was measured and the suitability was evaluated. The temperature conditions were carried out at 40°C, the same as the previously designed decontamination process, and the measurement was conducted by adjusting the pressure and volume through a syringe pump and a variable volume device. In addition, solubility was measured based on the observation of the ‘cloud point’ in which the image becomes cloudy and then bright. As a result of the experiment, several solubility points were measured at a pressure of 150 bar or less. If the flow rate ratio of supercritical carbon dioxide and auxiliary solvent derived from the results is applied to the soil decontamination process, it is expected that the process efficiency will increase in the future.

Catalytic conversion of ethanol over mesoporous silica based catalyst under supercritical condition

이진혁,이인구,최혜영,이관영 한국공업화학회 2018 한국공업화학회 연구논문 초록집 Vol.2018 No.0

Ethanol is potentially a promising source for the production of valuable chemicals or advanced biofuels with increased availability. For example, the ethanol has been used as a sustainable replacement for petroleum gasoline, but ethanol has a lower energy density and it absorbed water, which leading to the separation in storage system. As a transportation fuel, higher alcohols such as 1-butanol has much higher properties and that can alleviate many of problems associated with ethanol when gasoline blended with 1-butanol. However, the production rate of butanol yield from fermentation is lower than that of ethanol produce from yeast fermentation process. Thus, ethanol is more available as a basic source for the utilization of valuable chemical products than fuel application. In this study, the catalytic conversion of ethanol to other valuable components investigated over mesoporous silica based catalysts under supercritical condition.

Improvement of lignin oil properties by combination of organic solvents and formic acid during supercritical depolymerization

Park, S.Y.,Hong, C.Y.,Jeong, H.S.,Lee, S.Y.,Choi, J.W.,Choi, I.G. Elsevier Scientific Pub. Co 2016 JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS Vol.121 No.-

Supercritical treatment of ethanol organosolv lignin was conducted to produce lignin-derived bio-oil. The reaction was performed at 350<SUP>o</SUP>C for 40min with 3MPa hydrogen gas pressure. To improve the yield of lignin oil and inhibit repolymerization during supercritical treatment, formic acid was added to the solvent. The effect of formic acid was examined by gas chromatography mass spectrometry (GC/MS), gel permeation chromatography (GPC), and elemental analysis. The maximum yield of lignin oils was shown to reach up to 70wt% with the addition of formic acid. When 7% formic acid was used, the resulting lignin oil exhibited the highest monomer content at approximately 56mg/g and the lowest oxygen/carbon molar ratio (O/C) of 0.26. The main degradation products in the lignin oil were syringol, 4-methylsyringol, and p-cresol. The lignin oil contained a larger proportion of syringyl unit monomers than guaiacyl because yellow poplar is hardwood, consisting primarily of syringyls. The molecular weight of lignin oils increased with the addition of formic acid since lignin-derived oligomers were also produced. Meanwhile, experiments were performed using methanol and isopropanol to investigate the relationship between the solvent type and lignin depolymerization. Isopropanol led to a higher yield of lignin oil compared to ethanol, but amounts of monomeric products were much lower. Therefore, supercritical ethanol treatment with 7% formic acid under pressure from hydrogen gas is considered to be more effective when compared to other conditions, and this procedure demonstrated the possibility for better production of lignin-derived products during thermal decomposition reactions.

Development of Integrated Decontamination Process Using Supercritical Carbon Dioxide and Ethanol for Soil Contaminated With Cs, Sr, U

Seungil Ha,Kwangheon Park,Jinhyun Sung 한국방사성폐기물학회 2022 한국방사성폐기물학회 학술논문요약집 Vol.20 No.2

Korea faces decommissioning the nation’s first commercial nuclear power plant, the Kori-1 and Wolseong-1 reactors. In addition, other nuclear power plants that will continue to operate will also face decommissioning over time, so it is essential to develop independent nuclear facility decommissioning and site remediation technologies. Among these various technologies, soil decontamination is an essential not only in the site remediation after the decommissioning of the highly radioactive nuclear facility, but also in the case of site contamination caused by an accident during operation of the nuclear facility. But the soil, which is a porous material, is difficult to decontaminate because radionuclides are adsorbed into the pores. Therefore, with the current decontamination technology, it is difficult to achieve the two goals of high decontamination efficiency and secondary waste reduction at the same time. In this study, a soil decontamination process with supercritical carbon dioxide as the main solvent was presented, which has better permeability than other solvents and is easy to maintain critical conditions and change physical properties. Through prior research, a polar chelating ligand was introduced as an additive for smooth extraction reaction between radionuclides present as ions in soil and nonpolar supercritical carbon dioxide. In addition, for the purpose of continuity of the process, a candidate group of auxiliary solvents capable of liquefying the ligand was selected. In this research evaluated the decontamination efficiency by adding the selected auxiliary solvent candidates to the supercritical carbon dioxide decontamination process, and ethanol with the best characteristics was selected as the final auxiliary solvent. In addition, based on the decontamination effect under a single condition of the auxiliary solvent found in the Blank Test process, the possibility of a pre-treatment leaching process using alcohol was tested in addition to the decontamination process using supercritical carbon dioxide. Finally, in addition to the existing Cs and Sr, the possibility of decontamination process was tested by adding U nuclides as a source of contamination. As a result of this research, it is expected that by minimizing secondary waste after the process, waste treatment cost could be reduced and the environmental aspect could be contributed, and a virtuous cycle structure could be established through reuse of the separated carbon dioxide solvent. In addition, adding its own extraction capacity of ethanol used for liquefaction of solid-phase ligands is expected to maximize decontamination efficiency in the process of increasing the size of the process in the future.