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: A distillation process and apparatus for recovering high purity aromatic products from a mixed aromatic hydrocarbon feedstock containing benzene, toluene and xylene by use of distillation towers integrated by heat exchange whereby substantial savings in operating costs and apparatus costs are realized. The distillation apparatus includes a benzene distillation tower and heat exchanger, a first toluene distillation tower and external heater, a second toluene distillation tower and heat exchanger and a xylene distillation tower and external heater, whereby the benzene distillation tower and heat exchanger are operably connected to the first toluene distillation tower and external heater and the second toluene distillation tower and heat exchanger are operably connected to the xylene distillation tower and external heater.

Abstract: An improvement to a known process in which C.sub.8 aromatic hydrocarbons are treated to recover a desired isomer of xylene, and in particular o-xylene or p-xylene. A step in recovering isomers of xylene typically includes subjecting a mixture of xylenes to fractional distillation and drawing a stream rich in o-xylene from the fractionation column. The current improvement involves the steps of contacting the contents of the fractionation column with an isomerization catalyst, thereby isomerizing C.sub.8 aromatic hydrocarbons in the fractionation column toward equilibrium and consequently enhancing the effectiveness of the fractional distillation in the recovery of the desired xylene isomer. The process can be carried out in the xylene splitter of existing apparatus by making appropriate modifications thereto. It also can be carried out in newly-designed and fabricated apparatus. Embodiments are disclosed for favoring the production either of o-xylene or p-xylene.

Abstract: A processing cycle for separating C.sub.8 aromatics (mixtures of ortho-, para-, meta-xylene and ethylbenzene) is disclosed, in which a first subdivision of the mixture is preformed into two streams respectively comprising: para-xylene and ethylbenzene as the first stream; and meta- and ortho-xylene as the second stream followed by a separation of the first stream by rectification, during which ethylbenzene within specifications is obtained as the overhead fraction, with the second stream also being sent to a separation by rectification, with ortho-xylene within specifications being obtained as the bottom fraction. The possible content of C.sub.9 species can be furthermore removed by subsequent distillation.

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: o-Xylene cannot be separated from p-xylene and m-xylene by conventional distillation or rectification because of the proximity of their boiling points. o-Xylene can be readily separated from mixtures of p-xylene and m-xylene by azeotropic distillation. Effective agents are 3-methyl-1-butanol, methyl propionate and 3-pentanone.

Abstract: p-Xylene cannot be separated from m-xylene by distillation or rectification because of the proximity of their boiling points. p-Xylene can be separated from m-xylene by means of extractive distillation. Effective agents are 3-ethylphenol and isopropyl palmitate. Effective agents for separating mixtures of p-xylene, m-xylene and o-xylene are 2-butoxyethyl acetate and 1,1,1-trichloroethane.

Abstract: Ethyl benzene is difficult to separate from p-xylene by conventional distillation or rectification because of the closeness of their boiling points. Ethyl benzene can be readily separated from p-xylene by extractive distillation. An effective agent is 5-methyl-2-hexanone, also called methyl isoamyl ketone.

Abstract: Ethyl benzene is difficult to separate from xylenes by conventional distillation or rectification because of the proximity of their boiling points. Ethyl benzene can be readily separated from xylenes by azeotropic distillation. Effective agents for separating ethyl benzene from p-xylene are methyl formate, n-butanol and cyclopentanol; from p-xylene and m-xylene, n-butanol.

Abstract: Ethyl benzene is difficult to separate from o-xylene by conventional distillation or rectification because of the closeness of their boiling points. Ethyl benzene can be readily separated from o-xylene by extractive distillation. Effective agents are phenol, cresols, nitrotoluenes and cyclododecanol.

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: In a combination crystallization/xylene isomerization process for producing para-xylene crystals, the recovery section is modified to accommodate crystallizing and separating para-xylene crystals at two different temperatures (a higher temperature followed by a lower temperature). The benefit is a reduction in the overall energy cost of the process.

Abstract: The eutectic limit of para-xylene crystallization is overcome by enriching the concentration of para-xylene of the crystallization feed. This is accomplished by passing the crystallization feed stream through a selective adsorption zone to produce a para-xylene-enriched stream and a para-xylene-depleted stream. The para-xylene-depleted stream is passed to an isomerization zone to re-equilibrate the xylene mixture, thereby producing additional para-xylene. The para-xylene-enriched stream is passed to a crystallization zone to produce high purity para-xylene. The result is an increase in the overall para-xylene recovery.

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 of the solvent to charge flow rates ob 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 si then recycled to the charge. The solvent for desorption in stage (1) and washing in stage (2) is advantageously toluene.

Abstract: In the co-production of propylene oxide and styrene monomer, there is produced a sodium-containing heavy residue stream previously suitable only as a low grade fuel. In accordance with the invention, the heavy residue stream is contacted with acid having a molar concentration with respect to water above that which corresponds to the product salt solubility limit, and the resulting mixture is phase separated into an aqueous sodium salt-containing slurry phase and an organic phase reduced in sodium.

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: In the co-production oxide and styrene monomer, there is produced a sodium-containing heavy residue stream previously suitable only as a low grade fuel. In accordance with the invention, the heavy residue stream is contacted with aqueous acid, and the resulting mixture is phase separated into an aqueous sodium-containing phase and an organic phase reduced in sodium, and at least a portion of the organic phase reduced in sodium is converted to styrene monomer.

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: The benzene content of hydrocarbon gasolines is accomplished by (a) fractionating at least one hydrocarbon gasoline into a light fraction A, with an increased benzene content, and a heavy fraction B, with a reduced benzene content; (b) contacting the light fraction A at a temperature below room temperature with a gas containing at least a fraction of olefins in which the number of carbon atoms is from 2 to 5 per molecule so that at least a fraction of said olefins is absorbed in light fraction A; at the end of stage (b), separating a residual gas with a reduced olefin content from a liquid fraction C, with an increased olefin content; (d) passing the fraction C from stage (c) into an alkylation reactor so that at least a fraction of the benzene is alkylated by at least a fraction of the olefins; (e) fractionating the mixture emerging from stage (d) so as to produce, firstly, a gas phase chiefly comprising gases which were not converted during stage (d) and, secondly, a liquid phase, at least partly containing

Abstract: In the process flow scheme for chromatographically separating para-xylene from C.sub.8 isomers containing substantial amounts of C.sub.9 aromatic hydrocarbon impurities with BaX or KY zeolite adsorbent and heavy desorbents, e.g., tetralin and diethyltoluene, a bottoms stream from the extract fractionation column containing desorbent is recycled to the separation unit and a sidecut stream, containing C.sub.9 aromatic hydrocarbon impurities and a minor amount of the desorbent from the raffinate stream, is directed to the raffinate fractionation column, thereby removing C.sub.9 aromatic hydrocarbons from the desorbent before recycling the desorbent to the separation unit, and preventing C.sub.9 aromatics from building up in the desorbent input. A fractionator for the extract column bottoms stream is eliminated, lowering capital costs, and energy requirements for the raffinate column are reduced.

Abstract: In the process flow scheme for chromatographically separating paraxylene from C.sub.8 isomers containing substantial amounts of C.sub.9 aromatic hydrocarbon impurities with an X or Y zeolite adsorbent and heavy desorbents, e.g., tetralin and derivatives thereof and diethyltoluene, a drag stream is split from the extract fractionation column bottoms stream, containing desorbent and C.sub.9 aromatic hydrocarbon impurities for recycling to the separation unit, and is directed to the raffinate fractionation column, where C.sub.9 aromatic hydrocarbons are removed to prevent C.sub.9 aromatic hydrocarbons from building up in the desorbent input to the separation unit. A fractionator for the extract column stream is eliminated, lowering capital costs.

Abstract: Ethylbenzene is separated from xylene(s) by extractive distillation employing at least one copper(I) salt of a hydrocarbonsulfonic acid as extractant(s).

Abstract: The invention relates to a crystallization process for recovering a pure substance from a liquid mixture, a starting mixture being cooled down in a crystallization zone to form a crystal suspension from which crystals of the pure substance are recovered, wherein a) the crystal suspension is subjected to a crude preliminary separation in a (preliminary) separation zone to form a first mother liquor and a crystal mass containing relatively small particles, b) the crystal mass formed in a) is allowed to develop in a development zone at a temperature which is higher than that of the crystallization zone and lower than the melting point of the substance to be recovered, and is separated into a developed crystal mass and a second mother liquor, and c) the developed crystal mass formed in b) is separated into a third mother liquor and the intended pure substance in a separation zone, as well as to an apparatus suitable for performing said process.

Abstract: m-Xylene is difficult to separate from p-xylene or o-xylene by conventional distillation or rectification because of the close proximity of their boiling points. m-Xylene can be readily separated from p-xylene or o-xylene by using azeotropic distillation in which the agent is an aliphatic ester. Typical examples of effective agents are: for m-xylene from p-xylene, propyl butyrate or methyl valerate; for m-xylene from o-xylene, hexyl formate or methyl valerate.

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: 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: 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: Styrene cannot be easily removed from ethyl benzene or o-xylene by distillation because of the closeness of their boiling points. Styrene can be readily separated from ethyl benzene or o-xylene by means of azeotropic or extractive distillation using certain esters. Typical effective agents are ethyl isovalerate, propyl caproate, butyl propionate and hexyl formate.

Abstract: Ethyl benzene cannot be easily removed from styrene by distillation because of the closeness of their boiling points. Ethyl benzene can be readily separated from styrene by means of extractive distillation using certain nitrogenous organic compounds. Typical effective agents are adiponitrile, methyl glutaronitrile and nitrobenzene.

Abstract: m-Xylene is difficult to separate from o-xylene by conventional distillation or rectification because of the close proximity of their boiling points. m-Xylene can be readily separated from o-xylene by using extractive distillation in which the extractive agent is dimethylsulfoxide or a mixture of it with certain high boiling organic compounds. Typical examples of effective agents are: dimethylsulfoxide; dimethylsulfoxide and 1,4-butanediol; dimethylsulfoxide, nitrobenzene and diethylene glycol.

Abstract: m-Xylene is difficult to separate from o-xylene by conventional rectification or distillation because of the close proximity of their boiling points. m-Xylene can be readily separated from o-xylene by using extractive distillation in which the extractive agent is ethyl-2-hydroxybenzoate; methyl benzoate plus benzophenone; methyl benzoate, butyl benzoate and dimethylsulfoxide.

Abstract: Magnetizable adsorbent particles suitable for use in a magnetically stabilized fluidized bed and with a smaller particle size than conventionally formed composite adsorbents are prepared by introducing magnetizable particles such as magnetite or iron into a reaction mixture for forming a zeolite having adsorbent properties, such as zeolite Y. The zeolite is formed as a coating on the magnetizable particle.

Abstract: m-Xylene is difficult to separate from o-xylene by conventional rectification or distillation because of the close proximity of their boiling points. m-Xylene can be readily separated from o-xylene by using extractive distillation in which the extractive agent is dimethylformamide; dimethylformamide and 1,4-butanediol; dimethylformamide, adiponitrile and dihexyl phthalate.

Abstract: m-Xylene is difficult to separate from o-xylene by conventional distillation or rectification because of the close proximity of their boiling points. m-Xylene can be readily separated from o-xylene by using extractive distillation in which the extractive agent is a mixture polychloro aromatic compounds. Typical examples of effective agents are 2,3,4,6-tetrachlorophenol and p-dichlorobenzene; dimethyltetrachloroterephthalate, 2,3,4,6-tetrachlorophenol and 1,2,4,5-tetrachlorobenzene; 2,4,5-trichlorophenol, benzene hexachloride, o-dichlorobenzene and dioctyl phthalate.

Abstract: An improved process for concentration, separation and formation of paraxylene of the type wherein a hydrocarbon feed such as reformate is subjected to solvent extraction, fractionation and then Parex adsorption to remove paraxylene. The adsorber raffinate is isomerized to produce more paraxylenes and then recycled to the adsorber to remove the newly formed paraxylenes from the isomerization. The improvement includes a step of removing a stream from the process, downstream of the isomerization and introducing this stream upstream of the solvent extraction so that the concentration of non-aromatic such as naphthenes and paraffins produced in the isomerization will be reduced.

Abstract: m-Xylene is difficult to separate from o-xylene by conventional rectification or distillation because of the close proximity of their boiling points. m-Xylene can be readily separated from o-xylene by using extractive distillation in which the extractive agent comprises propoxypropanol; propoxypropanol and 1,4-butanediol; ethyl benzoate and ethylene glycol phenyl ether and benzyl alcohol.

Abstract: m-Xylene is difficult to separate from o-xylene by conventional rectification or distillation because of the close proximity of their boiling points. m-Xylene can be readily separated from o-xylene by using extractive distillation in which the extractive agent is ethyl-2-hydroxybenzoate; propoxypropanol puls 1,4-butanediol; sulfolane plus dimethylsulfoxide plus ethyl benzoate.

Abstract: An adsorptive separation method capable of effectively separating the desired component from a mixture containing the same at a high purity and a high recovery ratio, and easily coping with scale-up of the apparatus is disclosed.

Abstract: A vapor-liquid extractive distillation process utilizing a dialkyl sulfone containing 4 to 8 carbon atoms per molecule and at least one percent water as the solvent. The process according to this invention is of particular applicability in separating aromatics from nonaromatics in a BTX stream. The solvent system operates particularly well with relatively large amounts of water.

Abstract: Ethylbenzene and para-xylene and/or meta-xylene are difficult to separate by distillation because they boil only 2.3 C..degree. and 3.1 C..degree. apart. Ethylbenzene can be readily separated from the xylenes by using extractive distillation in which the extractive distillation agent is a mixture of pentachlorophenol admixed with certain chlorinated and/or oxygenated organic compounds boiling higher than the xylenes. A typical mixture comprises pentachlorophenol, benzene hexachloride and 1,2,4-trichlorobenzene.

Abstract: Ethylbenzene and para-xylene and/or meta-xylene are difficult to separate by distillation because they boil only 2.3 C..degree. and 3.1 C..degree. apart. Ethylbenzene can be readily separated from the xylenes by using extractive distillation in which the extractive distillation agent is a mixture of oxygen-containing organic compounds boiling higher than the xylenes. The mixture typically includes phthalic anhydride and maleic anhydride with or without a solvent.

Abstract: An off-gas from a process for producing styrene from ethylbenzene, which contains non-condensables; in particular, hydrogen, as well as some aromatics; in particular, ethylbenzene, is contacted with a higher boiling absorption oil to scrub aromatics from the off-gas and provide an off-gas essentially free of aromatics. The absorption step is employed as a final treatment of the off-gas; i.e., subsequent to initial treatment of the off-gas by chilling and/or ethylbenzene scrubbing to initially reduce the aromatics content thereof. A preferred absorption oil is the heavy byproducts obtained from a process for producing ethylbenzene, which contains polyethylbenzenes.

Abstract: A process for the adsorption separation of C.sub.8 aromatic isomers which comprises the steps of:(a) Supplying a C.sub.8 aromatic isomer mixture to a separation zone packed with a zeolite adsorbent to form an C.sub.8 aromatic isomer mixture adsorption band, the zeolite being a faujasite structured zeolite where at least about 60% of the exchangeable cation sites are replaced by potassium ion, and the remaining exchangeable cation sites being replaced by at least one metal cation selected from the group consisting of sodium, lithium, rubidium, cesium, magnesium, calcium, strontium, barium, nickel, copper, silver, manganese, cadmium, thallium and lanthanum ions;(b) Supplying a desorbent to the separation zone to develop the C.sub.8 aromatic isomer mixture adsorption band, the desorbent being an ether compound having a selectivity of about 0.3 to about 3.

Abstract: A method for separating benzene, toluene, xylenes and higher aromatics from admixtures containing them is disclosed, said method being based on the use of a solvent which is a 5-atom cyclic derivative of urea in which at least one of the nitrogen atoms is bound to an alkyl.Representative of this class of selective solvents is N,N'-dimethyl ethylene urea.Procedure details and examples are given.