Abstract: A process for the removal of .alpha.-methyl styrene from admixtures with cumene by hydrogenation in a catalytic distillation hydrogenation to selectively hydrogenate the side chains and produce cumene is disclosed. The crude cumene may be the byproduct of the cumene oxidation to produce phenol. The crude cumene also contains acetone, benzene, ethyl benzene and high and low boiling carbonyls, which are either removed simultaneously with the hydrogenation/distillation or removed first followed by the selective catalytic distillation hydrogenation.

Abstract: A mixture that contains benzene, other aromatic hydrocarbons and paraffinic hydrocarbons and/or naphthenic hydrocarbons that have 5 to 10 carbon atoms undergoes distillation in a first column, producing a distillate and a residue; a phase is drawn off laterally from the first distillation column, preferably at a point on the column where the benzene content is essentially at maximum where the toluene content is low; the phase that is drawn off is sent toward a first permeation stage, which produces a permeate that is enriched with benzene and a retentate; at least a portion of said retentate is recycled toward said first distillation column; the benzene-enriched permeate from stage (3) is sent to a second distillation column, from which the purified benzene comes out at the bottom and a distillate vapor comes out at the top; the distillate vapor is condensed, and the condensed distillate is sent at least in part to a second permeation stage; in said second permeation stage, a permeate that is also enriched in

Abstract: An apparatus and process for separating propane and benzene from alkylation reaction products in cumene production. An integrated fractionation tower combines the functions of propane separation, recycle benzene recovery as well as system dewatering to eliminate the need for separate depropanizer and dehydration columns and thus save capital and operating expenses.

Abstract: A process for preparing 1,2,4,5-dimethyldiisopropylbenzene includes conducting alkylation of p-xylene with propylene to produce an alkylation product, and crystallizing the alkylation product. A heteropolyacid-supported catalyst can be used as an alkylation catalyst for the reaction. The reaction solution produced from the alkylation reaction can be distilled before crystallization to improve yield and purity even more.

Abstract: A process for the management of polynuclear aromatic compounds produced in a hydrocarbon dehydrogenation zone wherein the effluent from the hydrocarbon dehydrogenation zone containing dehydrogenated hydrocarbons, dehydrogenatable hydrocarbons and trace quantities of mononuclear and polynuclear aromatic hydrocarbons is admixed with a recycle stream containing mononuclear aromatic compounds and the resulting admixture is contacted with an adsorbent to reduce the concentration of mononuclear and polynuclear aromatic compounds and to produce a stream comprising dehydrogenated hydrocarbons and dehydrogenatable hydrocarbons. An off-line spent adsorbent containing mononuclear and polynuclear aromatic compounds is contacted with a hot hydrogen-rich gas to recover at least a portion of said mononuclear and polynuclear aromatic compounds to thereby regenerate the spent adsorbent.

Abstract: A process for the management of polynuclear aromatic compounds produced in a hydrocarbon dehydrogenation zone wherein the effluent from the hydrocarbon dehydrogenation zone is contacted with an adsorbent to reduce the concentration of polynuclear aromatic compounds. The resulting dehydrogenated hydrocarbon having a reduced concentration of polynuclear aromatic compounds is reacted with methanol to produce an ether. A portion of the ether is contacted with a spent bed of adsorbent to recover at least a portion of the polynuclear aromatic compounds adsorbed thereon to thereby regenerate the adsorbent.

Abstract: This invention relates to a process for the removal of nitrogen compounds from an aromatic hydrocarbon stream comprising the nitrogen compounds by contacting the hydrocarbon stream with a selective adsorbent having an average pore size less than. about 5.5 Angstroms. The selective adsorbent is a molecular sieve selected from the group consisting of pore closed zeolite 4A, zeolite 4A, zeolite 5A, silicalite, F-silicalite, ZSM-5 and mixtures thereof. In one embodiment, the present invention comprises a combination of a fractionation zone and an adsorption zone wherein the feedstream is passed to the fractionation zone to provide a dry bottoms product stream essentially free of the nitrogen compounds and an overhead stream. The overhead stream is condensed to provide an aqueous stream and a hydrocarbon stream. The hydrocarbon stream is passed to an adsorption zone and a treated effluent recovered therefrom is returned to the fractionation zone.

Abstract: 1,2,4-Trimethylbenzene is difficult to sepparate from 1,2,3-trimethylbenzene because of the proximity of their boiling points. They are readily separated by azeotropic distillation. Effective agents are 1-propanol, methyl formate and 1-nitropropane.

Abstract: The C.sub.2 to C.sub.5 and heavier acetylenes and dienes in a thermally cracked feed stream are hydrogenated without significantly hydrogenating the C.sub.2 and C.sub.3 olefins. Additionally, the C.sub.4 and heavier olefins may be hydrogenated. Specifically, the cracked gas feed in an olefin plant is hydrogenated in a distillation reaction column containing a hydrogenation catalyst without the necessity of separating the hydrogen out of the feed and without any significant hydrogenation of the ethylene and propylene. A combined reaction-fractionation step known as catalytic distillation hydrogenation is used to simultaneously carry out the reactions and separations while maintaining the hydrogenation conditions such that the ethylene and propylene remain substantially un-hydrogenated and essentially all of the other C.sub.2 and heavier unsaturated hydrocarbons are hydrogenated. Any unreacted hydrogen can be separated by a membrane and then reacted with separated C.sub.

Abstract: To continuously produce and separate high purity p-xylene from a C.sub.8 aromatic hydrocarbon charge, successive use is made in combination of (1) a stage of separating low-purity p-xylene (75 to 98%) by simulated moving bed adsorption chromatography, with a ratio for the solvent to charge flow rates of 1.2 to 2.5; (2) a stage of purifying and washing the low-purity p-xylene by recrystallization (-25.degree. to +10.degree. C.); (3) a stage of catalytic isomerization of the charge which has been p-xylene-depleted by the separating stage (1); and recovering an isomerate which is then recycled to the charge. The solvent for desorption in stage (1) and washing in stage (2) is advantageously toluene.

Abstract: In the alkylation of benzene with propylene in a distillation column reactor to produce cumene the overheads from the distillation reactor are fed to a depropanizer where the unreacted benzene is separated from C.sub.3 's. Liquid propylene feed for the distillation column reactor is vaporized by indirect heat exchange with the overheads from the depropanizer to condense the overheads, thereby reducing the pressure in the depropanizer below what would be normally achieved with conventional condensing systems.

Abstract: To heat the circulating reboiler streams of multiple distillation columns a fired reboiler is provided for a first column requiring the most heat. A portion of the bottoms from the first column is passed through the tubes of the heater in the fired reboiler and recycled to the first column as is normal. A slip stream is taken from the recycle after heating and passed on to provide heat by indirect heat exchange to a second reboiler and if desired other reboilers or heat exchangers. The slip stream may then be recycled to the bottoms of the first column directly or to the circulating steam of the first reboiler. A portion of the recycled slip stream can be taken as feed into the second column.

Abstract: A method for recovering crystalline 2,6-dimethylnaphthalene comprising crystallizing in a scraped-wall crystallizer apparatus at crystallization temperature T, a mixture of low melting components, LM, having melting points of 70.degree. F. and below, and high melting components (HM), including 2,6-dimethylnaphthalene, having melting points above 70.degree. F., such that: ##EQU1## where HM is the total weight percent of high melting components, including 2,6-dimethylnaphthalene, in the mixture, and LM is the total weight percent of low melting components in the mixture, and where T is the temperature of the crystallization in degrees Fahrenheit, and where A is at least 1.0.

Abstract: An integrated process for the production of normal paraffins from a feed mixture of normal paraffins, iso-paraffins and aromatics is disclosed. The process integrates a normal paraffin sorption process and an aromatics sorption process. The normal paraffin product of the process of our invention meets the commercial requirements for production of detergents, including sufficiently-low concentrations of both iso-paraffins and aromatics. The process achieves these results without the need for two additional factionation columns that are necessary to prior unintegrated processes.

Abstract: Benzene is difficult to separate from cyclohexane or cyclohexene by conventional distillation or rectification because of the close proximity of their boiling points. Benzene can be readily separated from cyclohexane or cyclohexene by using extractive distillation. Effective agents are: for benzene from cyclohexane, methyl acetoacetate; for benzene from cyclohexene, ethyl acetoacetate.

Abstract: The pervaporative treatment of hydrocarbon feeds which have been exposed to air or oxygen and which contain mixtures of aromatic and non-aromatic hydrocarbons to selectively separate the feed into an aromatics rich stream and a non-aromatics rich stream is improved by the step of pretreating the hydrocarbon feed over an adsorbent such as attapulgite clay.

Abstract: A continuous solvent extraction process for the separation of aromatic hydrocarbons from a feedstock comprising aromatic and non-aromatic hydrocarbons provides more efficient heat utilization by using a lean solvent stream to heat the rich solvent stream as it passes from a primarily extractive stripping section to a section that primarily provides steam stripping. The feed stream is contacted with a lean solvent stream in an extraction zone to separate it into a raffinate stream comprising non-aromatic hydrocarbons and a first rich solvent stream comprising solvent, aromatic hydrocarbons and non-aromatic hydrocarbons. The first rich solvent stream passes to a first stripping zone section from which a first vapor stream is recovered and a second rich solvent stream is discharged. As the second rich solvent stream is passed to a second section of the stripping zone it is heated by heat exchange with the lean solvent stream that is recovered from the second stripping zone section.

Abstract: An improved process for the production of linear olefinic hydrocarbons by paraffin dehydrogenation and adsorptive separation is disclosed. Aromatic by-products normally formed in paraffin dehydrogenation are selectively removed using at least one aromatics removal zone. Removal of these aromatic by-products significantly increases the purity of the olefinic hydrocarbon product and increases the capacity of the adsorptive separation zone. The improved process is believed to increase the life of the adsorbent in the adsorptive separation zone and the life of the catalyst in the dehydrogenation zone.

Abstract: This invention provides a method for separating 2,6-diethylnaphthalene from a mixture of diethylnaphthalene isomers by contacting said mixture with zeolite producing the same powder X-ray diffraction pattern as faujasite and the method can efficiently separate 2,6-diethylnaphthalene from ethylation reaction products containing diethylnaphthalene isomers.

Abstract: A method for refining a methylnaphthalene-containing oil includes the steps of azeotropically distilling the methylnaphthalene-containing oil with ethylene glycol to produce a methylnaphthalene fraction having a reduced content of nitrogen compounds; and hydrodesulfurizing the methylnaphthalene fraction in the presence of a catalyst having loaded thereto at least one member selected from molybdenum, cobalt and nickel.

Abstract: The present invention is an integrated catalytic reforming/hydrodealkylation process that maximizes benzene recovery by incorporating refrigeration and pressure swing adsorption separation units. In the refrigeration separation unit, liquid reformate is used as a sponge oil to recover benzene from a hydrodealkylation purge gas stream, which in the past has been vented. The pressure swing adsorption unit remove impurities from a hydrogen-rich gas stream prior to use in the hydrodealkylation unit.

Abstract: An improved process for the production of alkylated aromatic compounds by paraffin dehydrogenation and aromatic alkylation is disclosed. Aromatic by-products normally formed in paraffin dehydrogenation are selectively removed using at least one aromatics removal zone. Removal of these aromatic by-products significantly reduces the deactivation rate of solid alkylation catalysts. The improved process produces a detergent alkylate product that is significantly more linear than that produced by the prior art process.

Abstract: A process is disclosed for the conversion of light aliphatic hydrocarbons such as propane into aromatic hydrocarbons and especially high purity benzene. The feed hydrocarbon is converted to aromatic hydrocarbons in a dehydrocyclodimerization zone. The product stream from the dehydrocyclodimerization zone which contains benzene, toluene, xylenes and C.sub.6 -C.sub.10 non-aromatics are separated into an overhead stream which contains the non-aromatic hydrocarbons and a small fraction of the benzene and a bottoms stream which contains the remainder of the benzene and other aromatic components. The overhead stream is then flowed to a conversion zone where the C.sub.6 -C.sub.7 non-aromatic hydrocarbons are cracked and the benzene is combined with the bottoms stream and further separated to give a high purity benzene product stream and a toluene, xylenes and C.sub.9 + product stream. The toluene, xylenes and C.sub.9 + product stream may further be separated into a toluene and xylenes product and a C.sub.

Abstract: It has been found that the aromatic byproducts normally formed in the dehydrogenation of normal paraffins to linear monoolefins are detrimental in the usual processes of aromatic alkylation using the dehydrogenation product mixture as an alkylation feedstock. In particular, when solids are used as the alkylation catalysts with recycle of the unreacted feedstock to the dehydrogenation reactor the aromatic byproducts increase to a level where they exert a significant decrease in the stability of the alkylation catalyst. When the aromatic byproducts are removed in whole or in part alkylation may be performed at a substantially lower temperature, which affords alkylated aromatics whose alkyl portion has greater linearity than that observed at a higher alkylation temperature.

Abstract: A process of recovering monoalkylbenzene and pure 1,3,5-trialkylbenzene from an isomeric mixture containing dialkyl- and trialkylbenzenes. The process comprises transalkylating a monocyclic aromatic compound with a mixture of dialkyl- and trialkyl-benzenes in the presence of an acidic mordenite zeolite under conditions such that monoalkylbenzene and predominantly 1,3,5-trialkylbenzene are formed. 1,3,5-trialkylbenzene is isolated in pure form from a mixture of the same and 1,2,4- and/or 1,2,3-trialkylbenzene by use of a dealuminated zeolite Y adsorbent.

Abstract: A continuous solvent extraction process for the separation of aromatic hydrocarbons from a feedstock comprising aromatic and non-aromatic hydrocarbons provides more efficient heat utilization by using a lean solvent stream to heat the rich solvent stream as it passes from a primarily extractive stripping section to a section that primarily provides steam stripping. The feed stream is contacted with a lean solvent stream in an extraction zone to separate it into a raffinate stream comprising non-aromatic hydrocarbons and a first rich solvent stream comprising solvent, aromatic hydrocarbons and non-aromatic hydrocarbons. The first rich solvent stream passes to a first stripping zone section from which a first vapor stream is recovered and a second rich solvent stream is discharged. As the second rich solvent stream is passed to a second section of the stripping zone it is heated by heat exchange with the lean solvent stream that is recovered from the second stripping zone section.

Abstract: A process for the fractionation of a gaseous mixture containing hydrogen, light aliphatic hydrocarbons and light aromatic hydrocarbons wherein following compression of the mixture and separation of one or more light fractions, a gas is contacted with light aliphatic hydrocarbons and then hydrogen is separated by permeation. A series of distillation steps makes it possible to isolate the aliphatic hydrocarbons and the aromatic hydrocarbons subsequent to the separations.

Abstract: Raffinate yield from solvent extraction is improved when the extract phase recovered from the solvent extraction process is subjected to a membrane separation step wherein a saturates/1-ring aromatics rich retentate is produced and a 2+ ring aromatics rich permeate are produced and the saturates/1-ring aromatic rich retentate phase is recycled to the solvent extraction process.

Abstract: A process for the production of alkylaromatic hydrocarbons uses a working fluid to reduce the costs of separating an unreacted aromatic feed substrate from aromatic hydrocarbon products. Unreacted aromatic substrate is combined with a light hydrocarbon, such as propane, to form a combined effluent stream. The combined effluent stream enters a flash separator where unreacted aromatic substrate is lifted overhead with the light hydrocarbon while heavier aromatic products are recovered below. The aromatic substrate and light hydrocarbon are easily separated in a simple separation zone. Lifting the aromatic substrate with the working fluid reduces the volume of aromatic substrate that remains with the aromatic product so that the more energy intensive separation of the aromatic substrate and aromatic product is performed on a reduced volume of material.

Abstract: The separation of aromatic hydrocarbons from mixtures of aromatic and non-aromatic hydrocarbon feeds under pervaporation conditions, is improved by the control of the amount of oxygen present in the feed. The amount of oxygen in the feed, such as heavy cat naphtha or other cracked feed, should be less than 30 wppm, preferably less than 10 wppm. The oxygen level in the feed can be controlled by the addition of small amount of oxygen scavenger into the feed. Hindered phenols are representative of useful oxygen scavengers.

Abstract: The yield, raffinate product quality, and throughput of the selective solvent extraction of hydrocarbon feeds is improved by subjecting the hydrocarbon feeds from which aromatic hydrocarbons are to be selectively solvent extracted to a membrane separation process which selectively permeates aromatics through the membranes to produce a permeate rich in aromatics and a retentate rich in saturates and 1-ring aromatics and subjecting this retentate to the selective solvent extraction process.

Abstract: A process for producing methylnaphthalenes is disclosed, comprising subjecting a fraction containing at least 50% by volume of components within the boiling range of 195.degree.-215.degree. C., which is obtained by distilling a raffinate resulting from the recovery of normal paraffins from a hydrodesulfurized kerosene fraction, to reforming reaction and then recovering methylnaphthalenes from the product oil.

Abstract: This invention relates to a process for extracting styrene from a styrene-containing hydrocarbon feedstock by:(a) reacting the feedstock with an anthracene at a temperature ranging of from about 175.degree. to about 275.degree. C. to form a styrene adduct with anthracene,(b) separating the adduct from the feedstock,(c) heating the separated adduct at a temperature of from between about 250.degree. to about 450.degree. C. to produce anthracene and styrene, and(d) individually separating styrene and anthracene from the mixture formed in step (c).

Abstract: A continuous process is presented for the production and recovery of a high purity stream of 2,6-dimethylnaphthalene. The process comprises the general steps of: fractionating a hydrocarbon feed stream to recover a process stream rich in the various isomers of dimethylnaphthalene; subjecting the process stream rich in isomers of dimethylnaphthalene to a selective adsorption step to produce at least two streams of dimethylnaphthalene isomers, one lean in the 2,6-dimethylnaphthalene isomer and subjecting the stream of dimethylnaphthalene isomers lean in the 2,6 isomer to isomerization to increase the concentration of the 2,6 isomer of dimethylnaphthalene therein and directing the isomerized stream back to the fractionation zone to further processing.

Abstract: The filter system includes a plurality of porous metal filter tubes and is used in a method for extracting high purity solid para-xylene crystals from a mother liquor feed slurry of mixed xylenes in liquid and crystal form utilizing a separation unit which includes a crystallization stage where the mother liquor slurry is cooled in at least one crystallizer to crystallize liquid para-xylene into solid crystals, an isomerization stage where xylenes, such as ortho-xylene and meta-xylene, are reacted over a catalyst bed to convert these xylenes into para-xylene, and a distillation stage where the mixed xylenes are separated from the impurities from which byproducts are obtained.

Abstract: In the method for the production of an aromate concentrate suitable for use as blending component for gasifier fuel, feed hydrocarbon mixtures having boiling ranges substantially between 40.degree. and 170.degree. C., are subjected, without any previous separation into individual fractions, to an extractive distillation employing N-substituted morpholine, substituents of which display no more than seven C-atoms, as selective solvent. Herewith, the lower boiling non-aromates with a boiling range up to about 105.degree. C., practically completely, and most of the higher boiling non-aromates with a boiling range between about 105.degree. and 160.degree. C., are recovered as raffinate, whereas the aromates, which are to be employed in whole or in part as blending component, come down in the extract of the extractive distillation.

Abstract: A process to purify t-butylstyrene from product containing substantial amounts of t-butylethylbenzene and small amounts of alkenyl-substituted styrene impurities by a combination of vacuum fractionation and vacuum evaporation in the presence a polymerization inhibitor, and treatment with a carbonaceous adsorbent. Such a product to be purified can be prepared by catalytically, oxidatively dehydrogenating over an alkaline pyrophosphate in the vapor phase t-butylethylbenzene containing about 95 wt. % or more of the p-isomer which can be made by alkylating ethylbenzene with isobutylene in a controlled manner in the presence of cooled concentrated sulfuric acid.

Abstract: A process for production of dimethylnaphthalenes is disclosed, comprising subjecting a raffinate resulting from the recovery of normal paraffins from a hydrodesulfurized kerosene fraction to reforming reaction and then recovering dimethylnaphthalenes from the product oil.

Abstract: A process for the production of alkylaromatic hydrocarbons uses a light hydrocarbon recycle to reduce the costs of separating an unreacted aromatic feed substrate from aromatic hydrocarbon products. Unreacted aromatic substrate is combined with a light hydrocarbon, such as propane, to form a combined effluent stream. The combined effluent stream enters a flash separator where unreacted aromatic substrate is lifted overhead with the light hydrocarbon while heavier aromatic products are recovered below. The aromatic substrate and light hydrocarbon are easily separated in a simple separation zone. Lifting the aromatic substrate with the light hydrocarbon reduces the volume of aromatic substrate that remains with the aromatic product so that the more energy intensive separation of the aromatic substrate and aromatic product is performed on a reduced volume of material.

Abstract: A process for separation of aromatic and nonaromatic hydrocarbons by solvent extraction is improved by incorporating control methods which optimize utility costs while maintaining desired product purities.

Abstract: Meta and para-diisopropylbenzene cannot be easily separated from each other by distillation because of the closeness of their vapor pressures. m-Diisopropylbenzene can be easily removed from p-diisopropylbenzene by azeotropic distillation using certain ethers. Typical effective azeotropic distillation agents are diethylene glycol diethyl ether and dipropylene glycol dimethyl ether.

Abstract: This invention relates to an improved more energy efficient process for the separation of aromatic and non-aromatic hydrocarbons from a mixed carbon feed which comprises the following steps:(a) contacting said feed in an extraction zone with an extraction solvent to provide an aromatic-rich solvent phase and a raffinate phase;(b) cooling said aromatic-rich solvent and raffinate phases;(c) introducing said cooled aromatic-rich solvent phase to a separation zone containing aromatic hydrocarbons and a solvent-rich phase containing mixed extraction solvent and water;(d) introducing said cooled raffinate phase to a separation zone in the presence of water as based on the total weight of water and the raffinate phase to provide a raffinate phase containing non-aromatic hydrocarbons and a solvent/water phase;(e) adjusting the water present in the solvent-rich phase of step (c) and the solvent/water phase of step (d);(f) recycling at least or portion the phases in step (e) to step (a);(g) separately contacting the ra

Abstract: A mixture of normally liquid organic compounds, particularly a light cycle oil obtained by the catalytic cracking of petroleum oils, is separated by contacting the mixture with an essentially anhydrous organic sulfoxide, particularly dimethylsulfoxide, to dissolve an organic extract in said sulfoxide and form an extract phase, comprising sulfoxide and the organic extract, and a raffinate phase, comprising the organic raffinate; diluting the extract phase with about 4.0 to 10.0 wt.

Abstract: Hydrocarbon solutions containing iodine or iodine-containing impurities are rendered essentially color-free by distillation in the presence of small amounts of a hydrocarbon soluble organometallic compound.

Abstract: A method is disclosed for the separation of aromates from hydrocarbon mixtures employed as entry products, by means of extractive distillation, employing as selective solvent N-substituted morpholine, the substitutions of which display no more than 7 C atoms. The raffinate produced as top product of the extractive distillation is subjected to a distillation, whereby the produced sump product with a solvent content between 20-75% by weight and a temperature between 20.degree.-70.degree. C., is led into a separation container and there separated into a heavy and a light phase. The heavy phase is then recycled into the extractive distillation column, whereas the light phase is recycled into the raffinate distillation column.

Abstract: An improved extractive separation process is described. This process is directed at splitting the feed and/or recycle stream to the extraction zone, to improve extraction zone performance. A further improvement may be achieved if at least a portion of the recycle stream is added to the extraction zone above the point where all the feed stream is added to the extraction zone.

Abstract: This invention discloses a process for the separation of diisopropenylbenzene from organic impurities in a dehydrogenation mixture comprising: (1) hydrogenating said dehydrogenation mixture to a maximum isopropenylstyrene concentration of no more than about 5% by weight in the presence of a rhodium catalyst and hydrogen to form a hydrogenated dehydrogenation mixture, followed by, (2) fractionally distilling said hydrogenated dehydrogenation mixture under conditions sufficient to separate said diisopropenylbenzene from said organic impurities in said hydrogenated dehydrogenation mixture.

Abstract: A process is disclosed for the recovery of a phenol-free cumene fraction from a mixture thereof with phenol and water. Said mixture is introduced into a first fractionation column at conditions to separate a bottom fraction comprising a major portion of said phenol and an overhead fraction comprising said cumene and water and a residual portion of said phenol. The overhead fraction is condensed to form an aqueous phase containing a minor portion of the residual phenol and a water-saturated organic phase comprising cumene and the balance of said residual phenol. The water-saturated organic phase is then further treated in a second fractionation column whereby cumene is recovered as an overhead fraction substantially free of phenol.

Abstract: Volatile liquid, such as benzene, isoprene, cyclopentadiene, butadiene present as a vapor in a blanket gas released from a storage zone for the liquid is absorbed from the gas by use of an absorption oil, followed by contacting of the rich absorption oil with an immiscible extraction solvent in an amount much less than the absorption oil to extract absorbed volatile liquid and provide a lean absorption oil. The volatile liquid is recovered from the extraction solvent, for example, by stripping. By recovering the volatile liquid from the small amount of extraction solvent, rather than the absorption oil, heating and cooling duties are decreased.

Abstract: A liquid product obtained by hydrodealkylation of hydrocarbon oil containing aromatic hydrocarbons is firstly subjected to rectification, then thus obtained substantially pure benzene is treated with clay substance under a temperature below 120.degree. C. A highly purified benzene especially good in color is obtained.