Solubility Of Benzene Research Articles

Variation of coal extract structure with molecular mass

Asphaltenes and benzene-insolubles, and their methylated counterparts, of high-yield supercritical gas (SCG) and hydrogen donor solvent (HDS) extracts have been separated by size exclusíon chromatography (SEC) on cross-linked polystyrene microspheres so as to investigate the variation in coal extract structure with molecular mass (MM). Narrow SEC fractions have been obtained which have been subjected to elemental, molecular mass (MM), functional group, n.m.r. and voltammetric analyses. The analytical results revealed that the M M range of the solvent fractions was 300 to ≈3000. With increasing MM the following trends were observed: aromaticity decreased, but the degree of condensation of aromatic nuclei did not vary significantly; the size of aliphatic substituents increased; and phenolic hydroxyl content decreased for SCG extract fractions but, in contrast, increased for HDS extract fractions. These variations about averages are considerable and demonstrate that caution is necessary in making use of analytical results for gross fractions. Solubility in benzene of coal extracts results from low MM or from low polarity for higher MM materials.

Pyrolysis of lignites and brown coal catalytically depolymerized with phenol to produce anisotropic coke or light oil

Pyrolysis of lignites and brown coal catalytically depolymerized with phenol was studied in order to design easy liquefaction or up-grading procedures effective under non-extreme conditions, where the recovery of phenol may be critical. The lignites were solubilized in pyridine very easily at low phenol/lignite ratios, but high ratios were required to induce their solubility in benzene—ethanol or THF. Although THF- and pyridine-soluble (abbreviated as THFS and PS, respectively) fractions exhibited fusibility in their single carbonization to produce grain cokes of optical isotropy, optical anisotropy can be developed by co-carbonization with petroleum pitches, suggesting that these fractions may be suitable as needle or blast furnace coke sources. The heat-treatment of PS with a hydrogen donor made it completely soluble in benzene. The recovery rates of bound phenol in the depolymerized lignite were at highest 57 and 36%, respectively, for the coking and heat-treatment processes, although the formation of alkyl phenols may occur in the heat-treatment.

Yubari coal depolymerization and catalysis of ZnCl2-containing melt for hydrocracking of the coal extract.

In the depolymerization of Yubari coal in the presence of tetralin, reaction time did not alter the average molecular weight of the coal extract but it effected deoxygenation and hydrogenation in which its nitrogen content remained constant. These effects are explained by referring to the average structure's change of two coal extracts. The coal extract from the depolymerization was hydrocracked over ZnCl2 or over ZnCl2-CuCl melt at 400°C for 3hr with an initial hydrogen pressure of 100kg/cm2. Analysis of PSH (higher boiling portion of pentane soluble) and of BS (benzene soluble) revealed that ZnCl2-CuCl was superior to ZnCl2 in removing the heteroatoms. The effectiveness of ZnCl2-containing melts for denitrogenation of coal and coal related materials was discussed on the basis of hydrocracking of quinoline over ZnCl2 and over quinoline-ZnCl2 complex. The close similarity of these products strongly suggests that denitrogenation of the basic fraction of the coal extract proceeds via the complex formation of nitrogen atoms with ZnCl2.

PROGRESSIVE HYDROTREATMENT OF HOKKAIDO COALS (JAPAN)

ABSTRACT Hokkaido coals were subjected to benzene extraction and non-catalytic hydrotreatment, alternatively, under progressive increase of temperature from 200 to 400 °C. For Taiheiyo coal the aliphatic materials in the hydrogen-rich part of the coal were converted to benzene soluble products at lower temperatures. With the increasing reaction temperature, aromaticity of the benzene solubles increased gradually. On the other hand, for Ohyubari coal, the structure of the benzene solubles were essentially the same for products obtained under all temperatures. Also, in the case of Taiheiyo coal (C : 76.9 %) the plastic state was not observed up to 400 °C, but for Ohyubari coal (C : 85.6 %) the onset of the plastic state was evident. It was assumed that there was an intimate relationship between the occurrence of plastic state and the structural uniformity of coal.

A Comparison of Coal Liquefaction Characteristics in a Continuous Stirred Tank Reactor with that in a Batch Micro-Atoclave

Liquefaction of Auefaction of Akabira coal by sufficient amount of tetralin was conducted in both a 5, 000 cm3 continuous stirred tank reactor and a 27 cm3 batch microautoclave reactor at 673 K and 5.4 MPa. The batch reactor was operated with different heating rates ranging from 4 K/min to 150 K/min so that the effects of the heating rate on the conversion of coal to benzene solubles could be evaluated. The residence time distribution of coal particles in the continuous reactor was also measured at room temperature.In the batch reactor, change of the conversion with time differed appreciably depending on the heating rate even if other operating variables were same. With increasing heating rates the conversion during the heating period decreased while the conversion level attained at the final stage of the reaction increased. Using the kinetic data together with the observed residence time distribution of the coal particles, the conversions in the continuous reactor were predicted. From a comparison between the predicted and observed conversions it was concluded that conversion in a continuous reactor can be predicted on the basis of kinetic data obtained in a batch reactor with the same heating rate as in the continuous one.

Effectiveness of both ZnCl 2- and SnCl 2-containing molten salt catalysts for hydrogenation of Big Ben coal in the absence of a solvent

Hydrogenation of Big Ben coal (Australian bituminous coal) with 9.8 MPa H 2 for 3h at 400 °C has been carried out using a batch autoclave system in the presence of a molten salt catalyst such as ZnCl 2, SnCl 2, ZnCl 2-KCl-NaCl (3:1:1 mol ratio) and SnCl 2-KCl (3:2). The hexane-soluble (HS) yield decreases in the order: SnCl 2-KCl, SnCl 2, ZnCl 2-KCl-NaCl, ZnCl 2. The use of SnCl 2-containing melt is characterized by higher yields of both HS and benzene-soluble (BS) fractions and the suppression of gas yield compared with the use of ZnCl 2. The average aromatic unit and the molecular weight of HS increase in the order: ZnCl 2, ZnCl 2-KCl-NaCl, SnCl 2, SnCl 2-KCl. Chromatographic separation of HS fractions indicates that the saturate content is lowest and polar-material content is highest with the SnCl 2-KCl melt: this fact coupled with the structural parameters suggests that HS material with SnCl 2-KCl melt has, on average, a reasonably-high-molecular-weight skeleton which has more alkyl chains and heteroatoms. Micrographs of resulting benzene-insoluble (Bl) materials clearly indicated that the Bl particles were larger when ZnCl 2 was used than when the other melts were used, the Bl particles in these cases being of similar size. Lewis acidity and the viscosity of the molten salt appear to be related, in part, to the size of the Bl particles.

Solubilization of benzene and cyclohexane by sodium deoxycholate micelles

Vapor pressure—solubility data were obtained for the aqueous systems benzene—sodium deoxycholate and cyclohexane—sodium deoxycholate at 25°C. The results are consistent with a mass action model similar to the BET equation. Equilibrium constants are inferred to characterize interactions of hydrocarbons with solubilization sites assumed to consist of units of four deoxycholate anions. Although addition of sodium chloride increases the micelle aggregation number (Ref. (16)), solubilization results are affected very little by variation in salt concentration. When pure liquid hydrocarbon standard states are employed, solubilization results for benzene and cyclohexane (at varying salt concentrations) are quite similar.

Solubility Measurements of Benzene and the Alkylbenzenes in Water by Making Use of Solute Vapor

Abstract Aqueous solubilities of benzene and of alkylbenzenes, toluene, ethylbenzene, propyl- and isopropylbenzene, (o-, m-, and p-) xylene, and (1,2,3-, 1,2,4-, and 1,3,5-) trimethylbenzene, have been measured. An apparatus is described which provides a convenient means of obtaining aqueous solutions saturated with solute vapor. The method involves introducing solute vapor, which is in equilibrium with a liquid solute, into water and circulating it in a closed system. This method has three principal advantages: (1) The solubility equilibrium can be attained within 3 min, (2) it can be determined whether the solubility obeys Henry’s law, and (3) based on Henry’s law, solutions of any desired concentrations of solute at a given temperature of water can be easily prepared.

Binderless moulding of green cokes delivered from solvent refined coal and ethylene tar pitch

Green cokes, derived from the co-carbonization of Solvent Refined Coals with ethylene tar pitch, have been moulded into discs without using a binder. Cokes with a range of size of optical texture have been prepared by control of the ratios of the two components of the carbonization blend. The appearance of the discs was assessed by optical and scanning microscopy after calcination to 1200° C. The most acceptable disc was prepared by moulding carbon of a heat treatment temperature (HTT) of 440° C. With cokes of HTT 440° C, dimished cohesion of the coke grains prevented the development of a strong disc on calcination. It is considered that the presence of benzene-soluble (BS) and benzene-insoluble/quinoline-soluble (BI/QS) fractions in the pitch systems contribute to cohesion of coke particles having a HTT of 440° C.

Precise vapour-pressure measurements of the solubilization of benzene by aqueous sodium octylsulphate solutions

Accurate vapour-pressure–solubility results have been obtained for aqueous solutions of sodium octylsulphate (SOS) and benzene at 15, 25, 35 and 45 °C. Thermodynamic constants are reported for reactions of benzene with SOS monomers and micelles; hydrophobic effects are important in stabilizing the aggregates formed between monomeric benzene and SOS species.The observed non-linearity of degree of solubilization with benzene activity indicates that benzene molecules interact cooperatively within the micelles. A mass-action model, employing a form of the Poisson distribution equations modified to account for cooperativity, provides an excellent fit of all the solubilization data at each temperature. Activity coefficients are reported for benzene in the micellar species, as functions of temperature and micellar composition.

Solubilization as a Separation Process

Abstract In this paper a separation process for hydrocarbon molecules is suggested, based on solubilization in aqueous solutions by surfactant micelles. A molecular thermodynamic approach to solubilization is formulated which relates the extent of solubilization and the selectivity to the structure and properties of the surfactant and of the solubilizate molecules. An evaluation of the solubilization characteristics of benzene and hexane in aqueous solutions of non-ionic octyl glucoside, anionic sodium dodecyl sulfate and cationic cetyl pyridinium chloride is made and solubilization phase diagrams for the above systems are constructed. These diagrams indicate the formation of micelles at concentrations which are lower than the critical micelle concentration of the surfactant alone. The calculations predict, for all three surfactants, preferential solubilization of (aromatic) benzene compared to (aliphatic) n-alkanes. The preferential solubilization of benzene is caused by its smaller molecular volume and lower interfacial tension against water. Preliminary experimental results using cetyl pyridinium chloride as surfactant and an equimolar binary mixture of hexane and benzene as solubilizates indicate a selectivity of over 7 for benzene compared to hexane, and a ratio of about one molecule of benzene solubilized for every surfactant molecule in the micelle.

Hydrocracking of Athabasca asphaltene over ZnCl 2-KCl-NaCl melts with or without an additive of some transition metal chlorides

Hydrocracking of Athabasca asphaltene over molten salts has been studied at 400 °C for 1 h at an initial hydrogen pressure of 9.8 M Pa. The hydrocracking over ZnCl 2-KCl-NaCl produced 57.0 wt% of pentanesolubles (PS), 4.7 wt% of benzene-solubles (BS) and 22.7 wt% of gases together with 15.6 wt% of coke. These melts containing NiCl 2 and CuCl, respectively, were examined, the former exerting a little better influence on reducing the coke yield. A small amount of coke (3.7%) and a higher conversion attained with ZnCl 2-KCl-NaCl-MoCl 5 suggested excellent properties of MoCl 5 for the hydrocracking of asphaltene. The sulphur contents of the PS and BS were lowest with melt catalysts containing MoCl 5. A compound-type separation of each pentane-soluble showed that in the presence of melt catalyst, monoaromatic and diaromatic contents increased greatly at the expense of polyaromatics and polar materials. The trend of catalytic activity of each melt for hydrocracking of asphaltene was found to be quite different from that for the decomposition reaction of tetrahydrothiophene in a continuous flow system.

Reaction mechanism for the hydrogenolysis of coal-derived preasphaltene

Preasphaltene, prepared in advance from hydrogenation of Akabira coal, was further hydrogenated at 385 °C with a hydrogen initial pressure of 9.8 MPa for various reaction times. According to the structural analysis and the variation of the inert oxygen content of the remaining preasphaltene and the benzenesoluble product, it is concluded that the conversion of preasphaltene to asphaltene plus oil is principally the reaction of the splitting of ether linkages which reduces the polymerization degree and the saturation of the aromatic rings with hydrogen which increases the solubility in benzene.

Mixed solubilization of benzene and cyclohexane in sodium deoxycholate micelles

Sodium deoxycholate micelles of two sizes, containing about 14 and about 40 molecules, were used as a model system to study the solubilization of benzene and cyclohexane mixtures. The results show that the composition of the intramicellar solution was the same as the composition of the contacting solution. This observation means that the interior of the micelle is hydrocarbonlike. The size of the micelle does not affect the solubilization process, indicating that the configuration of the primary micelle unit probably does not change as the micelle size increases. The solubilization data were obtained by direct extraction experiments at saturation and by vapor pressure measurements made from below saturation so that the possibility of emulsion formation was eliminated.

Effect of precarbonization temperature on liquefaction of lignites

Soya Koishi and North Dakota lignites were precarbonized at 350, 400 and 420 °C to reduce the oxygen content prior to hydrogenation at 400 °C under an initial hydrogen pressure of 10 MPa for 1 h. After hydrogenation, the solubility in tetralin and benzene remained almost constant to the precarbonization temperature of 420 °C for Soya Koishi lignite and 400 °C for North Dakota lignite. The hydrogen consumption decreased by ≈25% for the former and by ≈50% for the latter. The hydrogen content also decreased by precarbonization which increased the tetralin-insoluble fraction.

SOLUBILITIES OF BENZENE AND THE ALKYLBENZENES IN WATER—METHOD FOR OBTAINING AQUEOUS SOLUTIONS SATURATED WITH VAPOURS IN EQUILIBRIUM WITH ORGANIC LIQUIDS—

Abstract A method is presented which is simple and useful in attaining solubility equilibria of organic liquids in water. The solute vapour, which is in equilibrium with the liquid solute, is introduced into water and circulated in a closed system. It has been confirmed that Henry’s law applies to aqueous solubilities of benzene and the alkylbenzenes used.

Improved method to alkylate Yūbari coal of Japan using molten potassium under refluxing THF

A modification to Sternberg's procedures of reductive alkylation of coals is proposed. The ‘coal anion’ formation reaction is conducted under refluxing THF without any electron transfer agent and with molten potassium metal. The method was applied to Yūbari coal (86 wt % C) whereby varying reaction times (0.5–6 h) altered the lengths of alkyl groups (CH 3C 4H 9) added. In a typical experiment, a butylated Yubari coal, prepared by the 2 h reaction, contained 7 butyl groups per 100 original carbon atoms and solubility in hot benzene was 75 wt %. The numbers of alkyl groups introduced and the solubilities of coals increased with reaction time. Values obtained were comparable to those reported using conventional procedures which required longer reaction times and an electron transfer agent l.r. spectra of butylated coals showed strong adsorption peaks attributed to aliphatic groups. Benzene-soluble—pentane-insoluble material of the alkylated coal had less condensed aromatic components with more alkyl side-chains compared with Yūbari SRC, which were estimated by the Brown—Ladner method. Contamination of the alkylated coal by THF fragments seems to be negligible, since hydrogenated naphthalene, obtained after treatment with molten potassium, contains no alkylated products. The reaction proceeded also in HMPA, but not in straight-chain hexane.

Solubilities of volatile hydrocarbons in molten polystyrene.

Solubilities of volatile hydrocarbons, n-octane, n-nonane, n-decane, benzene, toluene, m-xylene, and mesitylene, in molten polystyrene were determined by gas chromatography in the temperature range from 150 to 225°C.On the basis of the thermodynamic relation between solubility and temperature, the heats of solution for these hydrocarbons were obtained.

Effect of solvent extraction sequence on the apparent distribution of coal liquid products

Asphaltenes and are terms widely used in coal liquefaction experimentation. They should represent well defined coal fractions which are obtainable by standard, reproducible and accurate methods. However, anyone in this field will immediately realize that there is a variety of methods being used [1--3]. Each method is internally consistent and therefore meaningful to the user, but a comparison of results from different laboratories is very difficult and sometimes meaningless. In our work, we have defined the following solvent extraction fractions: oils = n-pentane solubles asphaltenes = n-pentane insolubles, benzene solubles = benzene insolubles, pyridine solubles pyridine insolubles = unreacted coal This is an extension of petroleum chemistry terminology [4] since petroleum contains only oils and asphaltenes. It is also noted that the use of the term pre-asphaltenes does not necessarily imply that this fraction is formed before asphaltenes, but may actually form from a polymerization of asphaltenes and/or oils. Even with the above solvents, we found it necessary to determine the effect of the solvent extraction sequence. Three techniques were examined as identified below and described in the following section: 1. direct extraction 2. forward sequential extraction 3. reverse sequential extraction

Dose-dependent metabolic interaction between benzene and toluene in vivo and in vitro

When benzene or toluene was administered to rats ip in combination with the other, their disappearance rate from blood and the rate of urinary excretion of their metabolites were delayed compared with those when they were given separately. This metabolic interaction was found to be dose dependent. The metabolism of benzene or toluene studied in vitro with rat liver 10,000 g supernatant fraction was inhibited competitively by the presence of the other. The solubility of benzene and toluene in blood and their binding with bovine serum albumin were not influenced by the presence of the other, indicating that absorption and distribution are unaffected by their simultaneous presence. A human experimental exposure to a mixture of benzene and toluene revealed that there is no significant interaction between them with respect to their fate when exposure is near the threshold limit value.