Supercritical Fluid Extraction of Ethylene Oxide from Its Aqueous Solution

The mutual solubility of ethylene oxide and supercritical carbon dioxide was studied at T = 308 K in the pressure range P = 4.2–20 MPa, and the phase distribution of ethylene oxide in the water–ethylene oxide–supercritical carbon dioxide system was investigated at T = 308 and 323 K and P = 7.3–20.0 MPa.     

Cloud point behavior for poly(isodecyl methacrylate)+supercritical solvents+cosolvent and vapor-liquid behavior for CO<Subscript>2</Subscript>+isodecyl methacrylate systems at high pressure

Experimental cloud-point data of binary and ternary mixtures for poly(isodecyl methacrylate) [P(IDMA)] in supercritical carbon dioxide, dimethyl ether (DME), propane, propylene, butane and 1-butene have been studied experimentally using a high pressure variable volume view cell. These systems show the phase behavior at temperature of 308 K to 473 K and pressure up to 255 MPa. The cloud-point curves for the P(IDMA)+CO₂+isodecyl methacrylate (IDMA) are measured in changes of the pressure-temperature (P-T) slope, and with cosolvent concentrations of 0-60.1 wt%. Also, experimental data of phase behaviors for IDMA in supercritical carbon dioxide is obtained at temperature range of 313.2–393.2 K and pressure range of 5.8–22.03 MPa. The experimental results were modeled with the Peng-Robinson equation of state. The location of the P(IDMA)+CO₂ cloud-point curve shifts to lower temperatures and pressures when DME is added to P(IDMA)+CO₂ solution. The P(IDMA)+C₄ hydrocarbons cloud-point curves are ca. 16.0 MPa lower pressures than the P(IDMA)+C₃ hydrocarbons curves at constant temperature. This article is dedicated to Professor Chul Soo Lee in commemoration of his retirement from Department of Chemical and Biological Engineering of Korea University.     

超(近)临界流体中甲苯氧化成苯甲醛

分别研究了在超临界二氧化碳和近临界水中以过氧化氢为氧源、无催化剂条件下,甲苯氧化成苯甲醛的工艺优化及氧化反应动力学.研究结果表明,在超临界二氧化碳中的最佳工艺条件为：P=25 MPa,T=180 ℃,t=4 h,η=2.5.氧化反应呈现零级反应特征,反应活化能E_a=50.9 kJ&#8226;mol^-1.在近临界水中的最佳工艺条件为：P>P₀,T=350 ℃,t=1 h,η=3.5.氧化反应由两个一级反应组成连串反应,反应活化能分别为E_a1=89 kJ&#8226;mol^-1,E_a2=76 kJ&#8226;mol^-1.     

Study on elution ability of salicylic acid on ion exchange resins in supercritical carbon dioxide

The elution ability of salicylic acid on ion exchange resins in supercritical carbon dioxide has been studied. Some factors influencing elution recovery, including entrainer, temperature, pressure and the flow rate of supercritical fluid CO₂ are discussed in this work. The addition of a small amount of entrainer, such as ethanol, triethanolamine and their mixture to supercritical CO₂ can cause dramatic effects on the elution ability. The results show that the salicylic acid can be only slightly eluted from the resin with supercritical CO₂ alone with temperatures ranging from 307.15 to 323.15 K and pressures ranging from 10 to 30 MPa. Meanwhile, with the same T, P conditions, 40.58% and 73.08% salicylic acid can be eluted from the ion exchange resin with ethanol and ethanol + triethanolamine as the entrainer, respectively. An improved PR equation of state with VDW1 mixing rules is used to calculate the elution recovery of salicylic acid in supercritical CO₂ and the results agree well with the experimental data.     

Ternary phase equilibria of the iso-propanol+water+carbon dioxide system at high pressure

Ternary phase diagrams are presented for the system: iso-propanol(IPA)+water+carbon dioxide at temperatures from 15 to 70 °C and pressures from 7 to 17 MPa. The distribution coefficients of IPA between the dense phase carbon dioxide and water changed dramatically with temperature and pressure. In the vicinity of the critical point, distribution coefficients was low, yet at liquid-like densities carbon dioxide had a high affinity for IPA. Selectivity reversal was observed at differing pressures. High selectivity of CO₂ for IPA was achieved in the near-critical liquid and in supercritical carbon dioxide at high pressure.     

Extraction of essential oil from geranium (Pelargonium graveolens) with supercritical carbon dioxide

This study investigated the supercritical fluid extraction (SFE) of geranium essential oil from geranium (Pelargonium graveolens) using supercritical carbon dioxide solvent. The extraction yield was measured as a function of pressure, temperature and carbon dioxide flow rate. At low pressure (10 MPa) and high temperature (343 K), waxes were co‐extracted with the essential oil, resulting in artificially elevated essential oil extraction yields as no method was available with the SFE apparatus used to separate co‐extracted waxes and oil. At high pressure (30 MPa) and low temperature (313 K), the amount of wax co‐extracted decreased. Under these ‘optimum’ conditions, the extraction yield increased with decrease in flow rate giving a maximum extraction yield of 2.53%. All samples were analyzed by gas chromatography–mass spectrometry and the effect of pressure and extraction time on oil composition was studied. The percentage compositions of terpene hydrocarbons, terpenols, geraniol and geranyl esters were significantly affected by pressure and extraction time. The oil samples obtained by SFE were also compared with commercially obtained steam distilled samples. All major components of the commercially obtained oils were present in the SFE‐obtained oils; however, the percentage composition of the major components differed greatly between steam distilled and SFE oils. Copyright © 2005 Society of Chemical Industry     

Ruthenium(IV) dioxide-catalyzed reductive gasification of intractable biomass including cellulose, heterocyclic compounds, and sludge in supercritical water

Catalytic reduction gasification in the presence of ruthenium(IV) dioxide (RuO₂) in supercritical water was used to decompose intractable biomass. The gasification of model biomass samples (glucose, cellulose, and heterocyclic compounds), and low-purity biomass samples obtained from a paper-recycling facility (paper sludge) and from a sewage treatment plant (sewage sludge) were studied. In clear contrast to another catalysts, the RuO₂ catalyst completely gasified cellulose to produce mainly hydrogen, methane, and carbon dioxide under various conditions (e.g., 673 K at 30 MPa and 773 K at 50 MPa). As for heterocyclic compounds, nitrogen compounds did not deactivate the RuO₂ catalyst; the gasification of carbazole proceeded completely. Furthermore, paper sludge was almost completely decomposed in supercritical water with RuO₂ at 723 K.     

The Supercritical Fluid Extraction of Anthracene and Pyrene from a Model Soil: An Equilibrium Study

Abstract

Supercritical carbon dioxide (SC-CO₂) is used to extract two polycyclic aromatic hydrocarbons (PAHs), anthracene and pyrene, from a model soil at conditions ranging from 35 to 55 [ddot]C and 7.79 to 24.13 MPa. Equilibrium partition coefficients and Freundlich isotherm constants are determined for the two PAHs on white quartz sand and the model soil. The effect on equilibrium of additional water in the soil phase is also examined.     

Solubility of tri-iso-amyl phosphate in supercritical carbon dioxide and its application to selective extraction of uranium

The solubility of tri-iso-amyl phosphate (TiAP) in supercritical carbon dioxide (SCCO₂) was determined at 313–333 K with pressure ranging from 10 to 25 MPa. The solubility data of TiAP in SCCO₂ medium were correlated using four semi-empirical models. Selective extraction of uranium from simulated dissolver solution was demonstrated using SCCO₂ modified with TiAP. The extraction efficiency of uranium was found to be 95 ± 5%. The influence of temperature, pressure and acidity on the extraction of uranium was studied. An attempt was made to explain the plausible extraction mechanism.     

Hydrothermal reforming of bio-diesel plant waste: Products distribution and characterization

A viscous waste derived from a bio-diesel production plant, in the form of crude glycerol, was reacted under subcritical and supercritical water conditions and the product composition determined in relation to process conditions. Preliminary analysis of the original sample showed that the main constituent organic compounds were methanol (20.8 wt.%), glycerol (42.3 wt.%) and fatty acid methyl esters (33.1 wt.%). Uncatalyzed reforming experiments were carried out in a 75 ml Hastelloy-C batch reactor at temperatures between 300 °C and 450 °C and pressures between 8.5 MPa and 31 MPa. Oil/wax constituted more than 62 wt.% of the reactions products. At 300 °C, the main product was a waxy material containing mainly glycerol and fatty acid methyl esters. As the temperature increased to supercritical water conditions, low viscosity oils were produced and all of the glycerol was reacted. The oils contained mainly saturated and unsaturated fatty acid esters as well as their decomposition products. The gaseous products were carbon dioxide, hydrogen and methane and lower concentrations of carbon monoxide and C₂-C₄ hydrocarbons. No char formation was observed. However, during alkaline gasification with sodium hydroxide at 380 °C, the reaction products included a gaseous effluent containing up to 90% by volume of hydrogen, in addition to oil and significant amount of whitish solid residue (soap). Sodium hydroxide influenced the production of hydrogen via water-gas shift by the removal of carbon dioxide as sodium carbonate, but also decreased oil product possibly through saponification.     

A DRYING HEAT PUMP USING CARBON DIOXIDE AS WORKING FLUID

ABSTRACT

The application of carbon dioxide as working fluid in refrigeration and heat pump systems is regaining increasingly importance in view of the chlorofluorocarbon (CFC) substitution problem. It is both under ecological and economical aspects an attractive alternative to the hydrofluorocarbon (HFC) working fluids being in practical use. The thermophysical properties and characteristics of carbon dioxide are quite different from those of refrigerants used in conventional vapour compression cycles. Its application in conventional vapour compression refrigerating systems is limited by its critical parameters (t _c = 31.1°C and p _c = 73.8 bar). The possibility to use carbon dioxide also beyond these limits in high temperature processes, e.g., heat pumps, is given by the application of a trans-critical process. The design and construction of a commercial drying heat pump system (batch type cabinet dryer with 12 kW heating capacity and closed air circuit) using the natural working fluid carbon dioxide is shown and experimental results of investigations carried out are presented. Possible energy savings calculated theoretically are given for comparison.     

The selective thermal cis-trans isomerization of 1,2-diphenylsulfonyl ethylene in the presence of carbon dioxide

The selective isomerization of cis-1,2-diphenylsulfonyl ethylene to trans-1,2-diphenylsulfonyl ethylene proceeded in supercritical carbon dioxide above 393 K without an addition of catalyst. The product yield increased with increasing temperature and was almost constant against carbon dioxide density. The 73% of product yield was obtained at 493 K and 10 MPa of carbon dioxide pressure for 60 min. The product yield obtained in supercritical carbon dioxide was larger than those obtained in organic solvents. The supercritical carbon dioxide was a dilute solvent compared with organic solvent, which probably reduced the suppression of the reaction by dense solvent. Further, only cis-sulfonyl ethylenes isomerized among several cis-ethylene derivatives. The sulfonyl group played an important role for the isomerization.     

Enskog modulus,bρχ, for the gaseous and liquid states of carbon dioxide

The PVT behavior of carbon dioxide was used to establish a correlation for the Enskog modulus, bρχ in the dense gaseous and liquid regions. This modulus is presented for reduced temperatures ranging from T_R = 0.90 up to T_R = 3.5 and reduced pressures up to P_R = 40. The Enskog modulus finds use in the calculation of the effect of pressure on viscosity, thermal conductivity, and self-diffusivity. The value of the Enskog modulus for carbon dioxide at the critical point has been calculated to be (bρχ)_c = 0.885.     

High pressure measurements and molecular modeling of the water content of acid gas containing mixtures

Water content of three carbon dioxide containing natural gas mixtures in equilibrium with an aqueous phase was measured using a dynamic saturation method. Measurements were performed up to high temperatures (477.6 K = 400°F) and pressures (103.4 MPa = 15,000 psia). The perturbed chain form of the statistical associating fluid theory was applied to predict water content of pure carbon dioxide (CO₂), hydrogen sulfide (H₂S), nitrous oxide (N₂O), nitrogen (N₂), and argon (Ar) systems. The theory application was also extended to model water content of acid gas mixtures containing methane (CH₄). To model accurately the liquid‐liquid equilibrium at subcritical conditions, cross association between CO₂, H₂S, and water was included. The agreement between the model predictions and experimental data measured in this work was found to be good up to high temperatures and pressures. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3038–3052, 2015     

Supercritical carbon dioxide extraction of fatty and waxy material from rice bran

Waxy and fatty materials were removed from rice bran by supercritical carbon dioxide at pressures up to 28 MPa and temperatures between 40 and 70°C. The yields of the supercritical extraction were only 16–60% of those obtained by Soxhlet extraction with hexane. The highest yield was reached at the highest pressure and temperature used (28 MPa and 70°C), indicating that supercritical extraction of this lipid-bearing material could probably be improved at more severe extraction conditions. The supercritical extract obtained at operational conditions giving high yield was chromatographically characterized. Compared to the hexane extract, the supercritical extract was lighter in color and richer in wax content and long-chain fatty acids C₂₀−C₃₄. Triacontanol was the most abundant alcohol in both extracts. Tocopherol contents were similar.     

Desulfurization of Brown Coal in Water under Supercritical Conditions

A method for the desulfurization of brown coal by treatment in supercritical water (T = 673.15 K, P = 30 MPa) with the subsequent deposition of gaseous sulfur compounds on a copper substrate was proposed. The products were refined fuel with a low heat value of 24 MJ/kg and Cu₂S films with a thickness of 0.1 mm. The semiconductor Cu₂S films can be used for the preparation of thin-film photoelectric energy converters. The greatest degree of the removal of sulfur from the brown coal was observed after an hour. The main sulfur-containing gas formed upon the autoclave treatment of brown coal in supercritical water was H₂S.     

Supercritical fluid extraction of ethanol from aqueous solutions

The recovery of ethanol from aqueous solutions was studied by using supercritical carbon dioxide. At 333.2 K and 10.0 MPa, vapor–liquid equilibrium data of the mixture CO₂+ethanol+water were determined. No azeotrope was observed. Theoretical calculation of equilibrium stages was performed and compared with countercurrent column experiments. Separation of extract and solvent was optimized by multistage solvent distillation. The height of one theoretical stage was found to depend on the ethanol content of the liquid phase. Moreover, flooding point measurements were carried out with ethanol+water mixtures of different composition.     

Extraction of Furfural with Carbon Dioxide

Abstract

A new approach to separate furfural from aqueous waste has been investigated. Recovery of furfural and acetic acid from aqueous effluents of a paper mill has successfully been applied on an industrial scale since 1981.

The process is based on the extraction of furfural and acetic acid by the solvent trooctylphosphineoxide (TOPO). Common extraction of both substances may cause the formation of resin residues. Improvement was expected by selective extraction of furfural with chlorinated hydrocarbons, but ecological reasons stopped further development of this project.

The current investigation is centered in the evaluation of extraction of furfural by supercritical carbon dioxide. The influence of temperature and pressure on the extraction properties has been worked out. The investigation has considered the multi-component system furfural-acetic acid-water-carbon dioxide. Solubility of furfural in liquid and supercritical carbon dioxide has been measured, and equilibrium data for the ternary system furfural-water-CO₂ as well as for the quaternary system furfuralacetic acid-water-CO₂ have been determined. A high-pressure extraction column has been used for evaluation of mass transfer rates.     

Solubility of Jatropha and Aquilaria oils in supercritical carbon dioxide at elevated pressures

This study investigated experimental equilibrium solubilities of Jatropha curcas and Aquiliaria crassna oils dissolved in supercritical carbon dioxide at temperatures of 318-338 K and pressures of 20, 25, 30, 35 MPa. The highest solubility of J. curcas and A. crassna oil were 29.8 and 28.4 mg L⁻¹, respectively, at 338 K and 35 MPa. The oil solubilities and the concentration of triglycerides both increased with increasing temperature and pressure. Triglyceride molecules surrounded by carbon dioxide molecules may be proposed since solubilities increased with the flux of supercritical carbon dioxide. The solubility of these two oils linearly increased with the density of supercritical carbon dioxide. Experimental data of the oil solubility were successfully correlated by the Chrastil equation.     

Catalyst Preparation Using Supercritical Carbon Dioxide: Preparation of Rh/FSM-16 Catalysts and Their Catalytic Performances in Butane Hydrogenolysis Reaction

Supported Rh catalysts on FSM-16 were prepared by treating FSM-16, impregnated with [Rh(OAc)₂]₂ in supercritical carbon dioxide at 398 K and 30.3 MPa, followed by calcination and hydrogen reduction. The resulting Rh/FSM-16 catalysts were characterized by CO chemisorption, XRD, TEM, FTIR and EXAFS, and catalytic performances of the Rh/FSM-16 were tested in butane hydrogenolysis reaction. It is demonstrated that highly dispersed Rh particles are obtained by the supercritical CO₂ treatment. In the hydrogenolysis reactions, the supercritical CO₂-treated catalyst showed higher conversions and ethane formation.