Supercritical Fluid Extraction Fractionation Research Articles

Viscosity Mixing Rule and Viscosity–Temperature Relationship Estimation for Oil Sand Bitumen Vacuum Residue and Fractions

Removing heavy components through solvent separation is a potential routine for the viscosity reduction of Canadian oil sand bitumen. The mixing rule for the viscosity of extracted fraction is the basis of process simulation and optimization. In this study, supercritical fluid extraction fractionation was applied to separate Canadian oil sand bitumen vacuum residue (VR) into various fractions. The viscosity blending behavior of extracted fractions was experimentally evaluated. Several available viscosity mixing rules were tested. To predict the viscosity–temperature profile of derived fractions at different blending ratio, we proposed a new mixing rule based on empirical equation parameters. We also correlated the viscosity–temperature parameters to conventional bulk property, providing a method for the rapid viscosity estimation for VR, extracted fractions, and their mixtures.

Enhancement of mesocarbon microbead (MCMB) preparation through supercritical fluid extraction and fractionation

Mesocarbon microbeads (MCMBs) are a valuable carbon material, and the production of this material highly depends on the reaction conditions and feedstock properties. In the present study, supercritical fluid extraction fractionation (SFEF) technology was used to separate coal tar pitch (CTP) into a series of fractions to enhance MCMB preparation. After SFEF separation, most of the toluene-insoluble (TI) components were concentrated into the unextracted residue. First, optimal carbonization conditions were obtained for CTP through systematic experimental evaluations. Then, the SFEF fractions were heat-treated under the optimal conditions to produce MCMBs, and the relationship between chemical composition and product quality was revealed. Compared with CTP products, MCMBs produced from extracted SFEF fractions showed better morphology, and only a bulk mesophase with poor texture was generated from the unextractable residue. Moreover, the TI fraction had a significant negative impact on MCMB production in carbonaceous mesophase development. The results indicate that supercritical fluid extraction can be used to improve the quality of produced MCMBs by removing undesirable components.

渣油超临界萃取窄馏分的催化裂化反应

渣油超临界萃取窄馏分的催化裂化反应

Chemical Characterization of Polar Species in Colombian Vacuum Residue and Its Supercritical Fluid Extraction Subfractions Using Electrospray Ionization Ft-icr Mass Spectrometry

Compositional changes of Colombian vacuum residue and its supercritical fluid extraction fractionation (SFEF) subfractions were analysed by positive- and negative mode electrospray (ESI) coupled with Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS). The results showed different distribution of compounds among the SFEF subfractions. The most dominant classes were the nitrogen compounds N1 and the SFEF end-cut showed to be enriched in multi-heteroatom species. Detailed analysis of double bond equivalent (DBE) distribution revealed that pyridine compounds were more aromatic than pyrrole ones. Planar limit indicated high condensation degree of carboxylic acids species. Therefore, this work evidenced the utility of SFEF fractionation and ESI FT-ICR MS in the detailed characterization of polar compounds in vacuum residua.

Transformation of Nitrogen Compounds through Hydrotreatment of Saudi Arabia Atmospheric Residue and Supercritical Fluid Extraction Subfractions

Atmospheric residue (AR) from Saudi Arabia (SZAR) was subjected to supercritical fluid extraction fractionation (SFEF) and four extractable subfractions (SFEF-1–4) and an unextractable end-cut were obtained. SZAR and SFEF-1–4 were subjected to hydrotreatment (HDT) in a continuous mini fixed-bed reactor. Three commercial catalysts were used to remove the impurity in the feedstock. The composition and structural transformation of nitrogen (N)-containing compounds were investigated. Electrospray ionization (ESI) Fourier transform–ion cyclotron resonance mass spectrometry (FT-ICR MS) was used for molecular characterization of N-containing compounds of SZAR, extractable SFEF subfractions, and HDT products. Results showed that N1 class species with high aromaticity and/or low carbon number exhibited higher catalytic hydrogenation reactivity. N1 class species with lower aromaticity were removed regardless of chain length.

Transformation of Sulfur Compounds in the Hydrotreatment of Supercritical Fluid Extraction Subfractions of Saudi Arabia Atmospheric Residua

Atmospheric residue from Saudi Arabia (SZAR) was subjected to supercritical fluid extraction fractionation (SFEF) experiments. Four extractable subfractions (SFEF 1–4) and an unextractable end-cut were obtained. SFEF 1–4 were subjected to a hydrotreating (HDT) test in a mini-tubular reactor packed with commercial hydrodemetallization (HDM) and hydrodesulfurization (HDS) catalysts in order to determine the structural composition transformation of sulfur-containing compounds. Experiments were undertaken at a temperature of 360 °C, a hydrogen pressure of 14.7 MPa, a liquid hour space velocity (LHSV) of 0.25 h–1, and a H2/feed ratio of 650:1 (m3/m3). The SFEF subfractions and their products were subjected to analysis of their sulfur and nitrogen contents, using an ANTEK 7000S analyzer, and their saturates, aromatics, resins, and asphaltenes (SARA) compositions were analyzed using open column liquid chromatography. The detailed molecular composition of sulfur heteroatom species was determined by methylation, f...

Molecular Weight and Aggregation of Heavy Petroleum Fractions Measured by Vapor Pressure Osmometry and a Hindered Stepwise Aggregation Model

The hindered stepwise aggregation (HSA) model was used to elucidate the molecular aggregation in heavy petroleum fractions which were derived from supercritical fluid extraction fractionation (SFEF) of Venezuela Orinoco vacuum residue (VR). The SFEF fractions consisted of multiple extractable narrow fractions and a nonextractable end-cut. The SFEF fractions were diluted with toluene, and their number-average molecular weights (MWs) were determined using vapor pressure osmometry (VPO). The initial molecular association constants (K1) and aggregation hindrance factors (H) of the HSA model for each SFEF fraction were calculated from the VPO MWs at various SFEF solution concentrations. The results showed that the HSA model fit well with VPO MW data and the parameters of the HSA model are physically significant. The values of MW and K1 increased as the SFEF fraction became heavier. The SFEF end-cut had the highest K1 and lowest H value, in which the aggregates were 2 to 8 monomers. Except for the initial fraction, all the SFEF fractions formed aggregates at solution concentrations higher than 30 g/L. The value of K1 was dependent on the number of aromatic rings, whereas H is dependent on the size of aromatic ring and side-chain length. The VPO MWs of light SFEF fractions were in agreement with those determined from electrospray ionization (ESI) mass spectrometry (MS) or gel permission chromatography (GPC). The VPO MWs of the highly aggregated SFEF fractions were higher than those of ESI MS due to low ionization efficiency but were much lower than those of GPC.

Solvent extraction and purification of rosmarinic acid from supercritical fluid extraction fractionation waste: Economic evaluation and scale-up

Industry is increasingly interested in natural food preservatives, antimicrobial, and antioxidants due to their beneficial effects. The use of plant waste also presented itself to be a great opportunity in recovered bioactive compounds remaining in the residue. In this work, bioactive compounds were obtained from Rosmarinus officinalis in two different ways: firstly the supercritical fractionated rosemary extract with different composition was obtained from the plant material, and secondly a potent antioxidant-rosmarinic acid (RA) – was successfully extracted from the plant waste. A purification process scale-up of RA was proposed using GRAS solvent, and an economic evaluation was made for the overall process. A complete process to obtain bioactive compounds, antimicrobial (supercritical fluid extraction and fractionation extraction) and antioxidant (solvent extraction) was developed.

Coking Reactivity of Laboratory-Scale Unit for Two Heavy Petroleum and Their Supercritical Fluid Extraction Subfractions

The building of a separation-reaction network for heavy feedstock requires an understanding of the reactivity for subfractions. This paper proposes a study on the coking reactivity for two heavy petroleum samples, vacuum residua (VR) from China Liaohe and Venezuela Orinoco crude oils, and their supercritical fluid extraction fractionation (SFEF) subfractions. The properties of feedstocks and their SFEF series were analyzed, including density, molecular weight, elemental content, Conradson carbon residue (CCR), SARA components (saturates, aromatics, resins and asphaltenes) and structure parameters by nuclear magnetic resonance (NMR). All the samples were subjected to a laboratory-scale batch reactor to investigate the coking reactivity. Coke yield increased as the SFEF subfraction became heavier; while the yields of naphtha, diesel, and gas oil all decreased. The results show that the classic linear correlation between coke yield and CCR are not appropriate for separated fractions of VR. Instead, a negative power function was observed. Furthermore, the coke yield shows a linear relationship with aromaticity for both SFEF series. To precisely estimate coking reactivity for feedstocks and subfractions, a new SARA component based prediction model was carried out, which reveals the contribution of each component.

Molecular Characterization of Polar Heteroatom Species in Venezuela Orinoco Petroleum Vacuum Residue and Its Supercritical Fluid Extraction Subfractions

A Venezuela Orinoco petroleum vacuum residue (VR) was subjected to supercritical fluid extraction fractionation (SFEF) and separated into 13 extractable fractions and an unextractable end-cut. Detailed molecular composition of polar heteroatom species in the SFEF subfractions were determined by electrospray ionization (ESI) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). The SFEF subfractions were also subjected to high-temperature gas chromatography (GC) for their simulated distillation analysis, gel permeation chromatography (GPC) for their molecular distributions, and open column liquid chromatography for their saturates, aromatics, resins, and asphaltenes (SARA) compositions. In ESI FT-ICR analysis, the mass spectra showed that the mass range and maximum peak of the SFEF subfraction increased as the SFEF subfraction became heavier. Multifunctional group compounds, such as N1S1, N1S2, N1O1, and N2, show high relative abundance in heavier subfractions. The double bond equivalence (DBE) values and carbon numbers of all class species increased steadily as the SFEF subfraction became heavier. This indicated that the molecules in various SFEF subfractions are separated by their aromaticity and molecular weight. The SFEF end-cut could not be thoroughly characterized by ESI because of its low intensity, while basic species detected by positive-ion ESI were suppressed by a strong response of metal porphyrin species. Results from GPC and SARA compositional analysis show that the end-cut enriches most of the asphaltene in feedstock and has the highest apparent molecular size.

Investigating differential binding of polychlorinated dibenzo-p-dioxins/dibenzofurans in soil and soil components using selective supercritical fluid extraction

Supercritical fluid extraction (SFE) with pure carbon dioxide was performed at increasingly strong conditions to investigate differential binding of polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) in two impacted soils, in their sieved size fractions, and in small (a few mg) samples of industry-related waste products separated from impacted soil. The binding strengths of PCDD/Fs were shown to be different in the two soils, and in their different soil particle size fractions. As might be expected based on surface area considerations, one soil showed the strongest binding in the smallest (<5μm) sieved fraction. However, the other soil showed the strongest binding in the larger sized fractions, possibly indicating that process-related particles could be controlling PCDD/F binding. Selective SFE of various types of particles including black carbon and charcoal (separated from soil), and from a suspected process anode residue did show different PCDD/F binding behavior ranging from quite weak binding (charcoal) to very strong binding (anode particles). Shifts to the stronger SFE fractions in the soils after activated carbon treatment agreed well with the decreases previously found in the uptake of PCDD/Fs by earthworms, as well as decreases in their freely-dissolved aqueous concentrations in soil/water slurries. These results show that, as previously demonstrated for PAHs and PCBs, selective SFE can be a useful tool to investigate differences in PCDD/F binding behaviors in impacted soils and sediments and their component parts, as well as a rapid tool for estimating the effectiveness of activated carbon treatments on decreasing the bioavailability of PCDD/Fs in soils and sediments.

Supercritical Carbon Dioxide Extraction of Compounds with Antimicrobial Activity from Origanum vulgare L.: Determination of Optimal Extraction Parameters

Oregano leaves were extracted using a pilot-scale supercritical fluid extraction plant under a wide range of extraction conditions, with the goal of determining the extraction and fractionation conditions to obtain extracts with optimal antimicrobial activity. In this investigation, the essential oil–rich fractions were selectively precipitated in the second separator, and their chemical composition and antimicrobial activity were investigated. Gas chromatography–mass spectrometry analysis of the various fractions resulted in the identification of 27 compounds of the essential oil. The main components of these fractions were carvacrol, trans-sabinene hydrate, cis-piperitol, borneol, terpinen-4-ol, and linalool. Antimicrobial activity was investigated by the disk diffusion and broth dilution methods against six different microbial species, including two gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis), two gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa), a yeast (Candida albicans), and a fungus (Aspergillus niger). All of the supercritical fluid extraction fractions obtained showed antimicrobial activity against all of the microorganisms tested, although the most active fraction was the one obtained in experiment 5 (fraction was obtained with 7% ethanol at 150 bar and 40°C). C. albicans was the most sensitive microorganism to the oregano extracts, whereas the least susceptible was A. niger. Carvacrol, sabinene hydrate, borneol, and linalool standards also showed antimicrobial activity against all of the microorganisms tested, with carvacrol being the most effective. Consequently, it was confirmed that essential oil from experiment 5, with the best antimicrobial activity, also presented the highest quantity of carvacrol.

Combined use of supercritical fluid extraction, micellar electrokinetic chromatography, and reverse phase high performance liquid chromatography for the analysis of antioxidants from rosemary (Rosmarinus officinalis L.).

Antioxidants from rosemary were determined by the combined use of supercritical fluid extraction (SFE) prior to reverse-phase high-performance liquid chromatography (RP-HPLC) or micellar electrokinetic chromatography (MEKC). The separation of antioxidants found in the SFE fractions was achieved by using a new MEKC method and a published HPLC procedure, both with diode array detection. The characterization of the different antioxidants was further done by HPLC-mass spectrometry. Advantages and drawbacks of HPLC and MEKC for analyzing the antioxidants found in the different extracts are discussed. From the results it is concluded that HPLC renders higher peak area and is better in its reproducibility than MEKC; both techniques provide similar analysis time reproducibility. The main advantage of MEKC is its much higher separation speed, which is demonstrated to be useful for the quick adjustment of SFE conditions, allowing rosemary fractions of higher antioxidative power to be obtained quickly. Moreover, the possibilities of this approach for following the degradation of antioxidants are discussed.

Study of the distribution of the polychlorinated biphenyls in the milk fat globule by supercritical fluid extraction

The distribution of polychlorinated biphenyls (PCBs) in the milk fat globule has been studied by sequential extraction of four different lipidic fractions from powdered full-fat milk with supercritical carbon dioxide. Extractions were carried out in the dynamic mode in the pressure range 13.6–23.3 MPa at a temperature of 50°C. The levels of PCBs and short-chain triglycerides (SCT), medium-chain triglycerides (MCT) and long-chain triglycerides (LCT), as well as the cholesterol in these four supercritical fluid extraction (SFE) fractions were determined. Extracts obtained at lower pressures were found to be enriched in PCBs, SCT, MCT and cholesterol, while the concentrations of all these analytes decreased for subsequent extractions. Satisfactory quadratic correlations were found between the PCB and SCT and MCT levels ( r 2 in the range 0.9–0.999), and between the PCB and cholesterol levels ( r 2 in the range 0.8–0.999, except for PCB 105) determined in the SFE fractions. These results suggested a similar distribution of the PCBs and the cholesterol in the milk fat globule. This conclusion was also supported by the comparison of the PCBs and the cholesterol chemical structures as well as by the total PCB levels determined by SFE to those obtained by using different extraction methods. The classical requirement for the analysis of this kind of lipophilic pollutants of an exhaustive extraction of the lipids of the matrix to ensure their quantitative recovery has been revised.

Coking of Hydroprocessing Catalyst by Residue Fractions of Bitumen

The deposition of organic material, or coke, on hydroprocessing catalyst was studied using Athabasca bitumen vacuum residue (ABVB) and narrow fractions of ABVB, prepared by supercritical fluid extraction (SCFE) with n-pentane. The feed materials were diluted in a low-sulfur gas oil and hydroprocessed over a commercial NiMo/γ-Al2O3 catalyst in a 1 L continuous-stirred tank reactor at 440 °C. The coked catalysts were Soxhlet extracted with methylene chloride; then, carbon content, surface area, pore volume, and pore size were measured. Hydrodesulfurization activity was then measured using bitumen and dibenzothiophene as reactants.The SCFE fractions that contained only saturates, aromatics, and resins gave a low yield of carbon on the catalyst (<7.5 wt %). The asphaltene-rich fraction gave higher coke yields, both on the catalyst and in the reactor, and a lower H/C ratio than the lighter fractions. In the worst case with asphaltene-rich feed, over half of the surface area and pore volume of catalyst was lost due to coke deposition on the catalyst. HDS activity of the spent catalyst decreased monotonically with increasing carbon content on the catalyst. A portion of the carbonaceous material, or coke, on the catalyst was mobile and reactive at the conditions used for hydroprocessing of bitumen. The data suggested that this mobile adsorbed material had a significant impact on the observed activity of the catalyst.

Step by step modeling for thermal reactivities and chemical compositions of vacuum residues and their SFEF asphalts

In this paper, thermal conversions of 40 samples, including eight vacuum residues (six Chinese vacuum residues from Daqing, Dagang, Gudao, Shengli, Huabei and Liaohe crudes, two from Oman and Saudi Arabia Light crudes) and their deoiled asphalts with different yields obtained by supercritical fluid extraction fractionation (SFEF) technique were carried out in a 100-ml autoclave at 410°C and 1 h. The elemental composition (C, H, S and N), SARA (saturates, aromatics, resins and asphaltenes) composition and average molecular weight (MW) of the feedstocks were determined, and their average structural parameters were elucidated. It is found that the cracking and condensation conversion of the samples were correlated with their H/C ratio, contents of sulfur (S%) and nitrogen (N%), MW, and SARA composition (weight percentages of saturates (Sat), aromatics (Ar), resins (Re) and asphaltenes (Asp)). The results obtained by a non-linear regression fit method indicated that the characterization factors K r or K r′ for thermal cracking defined by following two equations: K r =( H/C) 0.257( S%) 0.158( N%) 0.184( MW) −0.151 or: K r ′=( Sat) 0.026( Ar) 0.008( Re) 0.380( S%) 0.170( MW) −0.230 can characterize well the thermal cracking reactivity of the eight vacuum residues and their SFEF asphalts at the 410°C and 1 h. Moreover, the characterization factors K c or K c′ for thermal condensation defined by the following two equations: K c =( H/C) −3.80( MW) 0.40 or: K c ′=( H/C) −3.80( Re+Asp) 0.30( MW) 0.24 can characterize well the thermal condensation reactivity of most samples at the same reaction conditions. It is also found that the yields of toluene insolubles of the feedstocks were correlated linearly with the concentration ratio of asphaltenes to resins plus aromatics of the cracked residues. This indicates that the formation of coke was the result of not only the condensation reaction of asphaltenes but also the phase separation of the colloidal system of residues.

Step-Wise Fractionation and Recovery of Aquatic Fulvic Acid by Modified Supercritical Fluid CO2- Methanol Extraction at Near Critical Temperature

Modified supercritical fluid “SF” CO2 -methanol mixture was used, under step-wise gradient conditions at near supercritical temperature, to fractionate Suwannee River reference fulvic acids (FA) into three fractions. The method was developed after a systematic study of the solubility of FA in SF CO2-methanol solvent system. Optimum supercritical fluid extraction (SFE) conditions were established at constant temperature of 70 °C and constant pressure of 2,500 psi; using modified CO2 fluid mixed with methanol at 18, 24 and 100 percent, respectively. The dynamic extraction conditions were designed to achieve marcketable differences in the fluid solvent power. Fractions were characterized by total uv absorption and fluorescence emission. Under optimum conditions, fractions were collected and characterized by uv absorbance ratio at λ 400/λ 254 nm using non-column HPLC with uv PDA detector. The average total mass recovery of all three fractions was 102 % and coefficient of variation of 6.8%. The first fraction represented 21.5 of total FA and exhibited absorbance ratio of 0.11. The second fraction represented 55 % of total FA and exhibited almost twice the absorbance ratio. The third fraction represented 25 % of the total FA and exhibited absorbance ratio of 0.30. Total sample and fractions were analyzed using C-18 RP-HPLC with uv-vis PDA and fluorescence detection. RP-HPLC chromatograms of the SFE fractions showed the resolution of the same number of peaks as the total sample, but with different uv absorption and fluorescence emission intensities. The overall results provide some insight on the structural features of FA.

CHARACTERIZATION OF CHEMICAL HETEROGENEITY OF GRAFT COPOLYMER BY CONVENTIONAL SEC

Poly(methyl methacrylate) grafted with poly(dimethyl-siloxane) was investigated by size exclusion chromatography coupled with refractometric and low-angle laser light scattering detectors. Using successively toluene and tetrahydrofuran as eluents, a variation in chemical composition and molecular weight of individual copolymer blocks as a function of hydrodynamic volume were measured. Chemical composition distribution and heterogeneity parameters of the copolymerization product were approximated and compared with the results obtained by supercritical fluid extraction fractionation and by fractionation in demixing solvents.

Integrated supercritical fluid extraction, bioassay and chemical screening methods for analyzing vapor-phase compounds of an environmental complex mixture: Diesel exhaust

The integration of bioassay and chemical analyses for vapor-phase compounds in environmental complex mixtures is a challenging process due to the volatility and the limited amounts of compounds collected and subsequently assayed. The advantage of an integrated approach is that the bioassay could aid in determining the most biologically active fractions for further chemical analyses. Previously, we reported on the use of supercritical fluid extraction (SFE) in conjunction with a Salmonella microsuspension assay to measure mutagenic activity in model vapor-phase mutagens. The procedure was effective in minimizing losses of the vapor-phase samples. In the present study, we performed the bioassay and chemical characterization of the vapor-phase mutagens using the exhaust from a medium heavy-duty diesel truck as a model complex mixture. Compounds present in undiluted diesel exhaust were trapped using a sampling train consisting of a Teflon filter, polyurethane foam (PUF) and XAD-4 (XAD), in series. Compounds in the PUF and XAD samples were extracted by SFE using supercritical carbon dioxide, and fractions were collected based on increasing pressures. For the bioassay, the Salmonella microsuspension assay was used throughout with tester strains TA98 and TAIOO, with and without the addition of metabolic enzymes (± S9). The two most mutagenic fractions from PUF were further fractionated using high performance liquid chromatography (HPLC). Chemical analyses of the HPLC fractions were by gas chromatography with a mass selective detector (GC/MS). Compounds present in these PUF SFE fractions included substituted naphthalenes, biphenyls, fluorenes, dibenzothiophenes and phenanthrenes or anthracenes. Compounds present in the XAD SFE fractions included substituted benzenes and naphthalenes, alkyl naphthalenes, and indenes. The vapor-phase mutagens present in diesel exhaust appeared to be more mutagenic in tester strain TA100 (with S9) compared to TA98, suggesting that the mutagenic compounds are different than those responsible for mutagenic activity in particulate matter where TA98 mutagenicity dominates. Specific mutagenic activities of the total vapor-phase component in TA 100 (with or without S9) were very similar to those of the total particulate component, suggesting that the vapor-phase of diesel exhaust may be an important source of mutagenic compounds in the environment.