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: 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: Benzene and other aromatics are separated from a stream of mixed hydrocarbons containing both aromatics and non-aromatics by extractive distillation with a solvent system containing dimethyl sulfoxide and optionally a co-solvent, preferably water, followed by distillation stripping of the aromatics from the enriched solvent system, and recycle of the lean solvent system to the extractive distillation step.

Abstract: The present invention discloses a method to separate each component from a mixed solution of organic solvents obtained during the production of .alpha.-L-aspartyl-L-phenylalanine methyl ester, which is useful as a sweetener, namely, a mixed solution of acetic acid and toluene or a mixed solution of acetic acid, toluene and formic acid, recovering each component with a high recovery ratio with as small number of operations as possible. The method rationalizes the process and is highly valuable in practical use.

Abstract: A method is provided for the recovery of aromatic hydrocarbons from the extract phase of aromatic-selective solvent extraction process which involves withdrawing a vapor side-cut fraction containing aromatic hydrocarbons and solvent from a stripping zone and passing the side-cut fraction to a rectification zone which can be refluxed with an aqueous condensate. The benefits of the invention are that the introduction of the rectification zone bottoms to the bottom of the stripping section provides an aromatic product comprising less than 100 wt. ppm. solvent, provides improved stripping over prior schemes, and reduces the flowrate of stripping medium throughout the stripping zone which results in energy saving.

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: Methods are provided for the recovery of aromatic hydrocarbons from the extract phase of aromatic-selective solvent extraction processes which involve withdrawing a vapor side-cut fraction containing aromatic hydrocarbons and solvents from a stripping zone and passing the side-cut fraction to a rectification zone which can be refluxed with aromatic hydrocarbons or aqueous condensate.

Abstract: The invention provides a method for removing mercury from a liquid hydrocarbon feed material by (a) removing those components having a higher molecular weight than the desired hydrocarbon from the feed material, (b) removing water from the feed material, and thereafter (c) removing mercury from the feed material. Mercury can be removed to an extremely low concentration of 0.001 ppm or lower from a wide variety of liquid hydrocarbon feed materials containing either a relatively large amount or a trace amount of mercury.

Abstract: Extractive distillation processes for separating aromatic hydrocarbon(s) or cycloalkane(s) or alkene(s) from close-boiling alkane(s) are carried out with a solvent including at least one N-alkyl-2-thiopyrrolidone compound, preferably N-methyl-2-thiopyrrolidone. Optionally, the solvent additionally contains a cosolvent, preferably tetraethylene glycol or N-(.beta.-mercaptoethyl)-2-pyrrolidone or unsubstituted sulfolane.

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: Nitration Grade benzene is made from a benzene stream with impurities including olefins by first fractionally distilling the benzene to a purity of at least 99 mole percent and subsequently passing the stream in a liquid phase in the presence of hydrogen through a hydrogenation step with a palladium catalyst under conditions such that substantially all olefins remaining in the stream are hydrogenated to paraffins.

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: 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: A process and apparatus are disclosed for the production of gasoline from a C.sub.4.sup.- fuel gas containing ethene and propene and catalytic reformate containing C.sub.6 to C.sub.8 aromatics. The C.sub.4.sup.- fuel gas is contacted with debutanized catalytic reformate over a zeolite catalyst under process conditions to convert ethene and propene in the C.sub.4.sup.- fuel gas to C.sub.5.sup.+ aliphatic and aromatic hydrocarbon gasoline and to convert C.sub.6 to C.sub.8 aromatics in the reformate to C.sub.7 to C.sub.11 aromatic hydrocarbon gasoline. Reformer fractionation system containing debutanizer column and separator stabilizes effluent gasoline and recycles unconverted light aromatics.

Abstract: Meta and para-diisopropylbenzenes cannot be easily separated from each other by distillation because of the closeness of their vapor pressures. m-Diisopropylbenzene can be readily removed from p-diisopropylbenzene by azeotropic distillation using certain alcohols. Typical effective azeotropic distillation agents are diethylene glycol butyl ether, diethylene glycol methyl ether and o-isopropyl phenol.

Abstract: Acetone cannot be easily separated from benzene in high purity by distillation because of the closeness of their vapor pressures. Acetone can be readily removed from benzene by azeotropic distillation using certain aromatic hydrocarbons. Typical effective azeotropic distillation agents are: toluene, ethyl benzene and mesitylene.

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: 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: Vinylaromatic compounds are stabilized against undesired polymerization by adding to the vinylaromatic compounds small amounts of zinc or nickel salts of dialkyl dithiocarbamates, specifically p-diisopropenylbenzene can be stabilized by the use of zinc dibutyldithiocarbamate.

Abstract: Isopropenylstyrene, present in t-butylstyrene in small quantities as an impurity, is removed by extractive distillation using sulfolane as solvent.

Abstract: Disclosed is a process for the distillation of readily polymerizable vinyl aromatic compounds and a new polymerization inhibitor therefor. The process comprises subjecting a vinyl aromatic compound to elevated temperatures in a distillation system in the presence of a new polymerization inhibitor comprising 2,6-dinitro-p-cresol. Also disclosed is a distillation method and apparatus for use with this inhibitor.

Abstract: Solvents which may be used as mediums for the polymerization of olefinic hydrocarbons to form polymers useful as membranes in a gas separation process require purification to remove any impurities which will effect the aforesaid polymerization. Purification of these solvents such as cyclohexane may be effected by treating the solvent with titanium tetrachloride, contacting the solution with an adsorbent such as silica gel and thereafter distilling the solvent in the presence of a purification agent such as an alkaline metal aluminum hydride or borohydride.

Abstract: A process of extractive distillation for separating components easily soluble in a polar solvent from at least two hydrocarbon mixtures having different contents of the easily soluble components by extractive distillation using said polar solvent, which comprises feeding a hydrocarbon mixture containing a larger amount of the easily soluble components, as a gas, into the middle or lower portion of an extractive distillation column, feeding a hydrocarbon mixture containing a smaller amount of the easily soluble components, as a liquid, to the upper portion of the extractive distillation column, and subjecting them to extractive distillation.

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: 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: This invention provides a process for obtaining m-methylstyrene from a mixture with p-methylstyrene that comprises hydrogenating a mixture of p-methylstyrene and m-methylstyrene in the presence of a zeolite having a Constraint Index of about 1 to about 12, a silica to alumina mole ratio of at least about 12, and a dried crystal density of not less than about 1.6 grams per cubic centimeter, modified with at least one element of Group IA, IIA, IVB, or VB of the Periodic Chart of the Elements and a metal of Group VIII of the Periodic Chart of the Elements; thereby obtaining a mixture of m-methylstyrene and p-ethyltoluene, and removing p-ethyltoluene by distillation.

Abstract: Indene is separated from close boiling, olefinically unsaturated alkylaromatic compounds by extractive distillation. For example, indene is separated from trans-.beta.-methylstyrene, and from 2-, 3- and 4-methylstyrene by extractive distillation using 1-methyl-2-pyrrolidone as the extracting agent.

Abstract: Disclosed is a process for the distillation of readily polymerizable vinyl aromatic compounds and a new polymerization inhibitor therefor. The process comprises subjecting a vinyl aromatic compound to elevated temperatures in a distillation system in the presence of a new polymerization inhibitor comprising 2,6-dinitro-p-cresol. Also disclosed is a distillation method and apparatus for use with this inhibitor.

Abstract: A process for isolating butadiene by means of a selective solvent from a C.sub.4 -hydrocarbon mixture which contains butadiene, small amounts of oxygen, hydrocarbons which are more soluble than butadiene in the selective solvent and hydrocarbons which are less soluble than butadiene in the selective solvent, wherein the C.sub.4 -hydrocarbon mixture is separated, by extractive distillation, into a distillate containing the less soluble hydrocarbons, a stream of butadiene and a stream containing the more soluble hydrocarbons, a mixture of oxygen and C.sub.4 -hydrocarbons is separated out of the C.sub.4 -hydrocarbon mixture in a distillation zone upstream of the extractive distillation, and the bottom product is fed to the extractive distillation.

Abstract: Cyclohexylbenzene is separated from a cyclohexylbenzene-cyclohexanone-phenol admixture by liquid-liquid extraction with a non-polar solvent such as hexadecane and a polar solvent, such as sulfolane, diethylene glycol, or mixtures with water. Cyclohexylbenzene is separated from the non-polar phase by fractional distillation. Phenol and cyclohexanone are separated from the polar solvent by fractional distillation.

Abstract: The recovery of a hydrocarbon capable of autopolymerization from an air stream by absorbing the hydrocarbon with a plasticizer and separating the hydrocarbon from the plasticizer by vacuum and atmospheric distillation.

Abstract: A cyclohexylbenzene-cyclohexanone-phenol-containing mixture, for example as obtained by the cleavage of cyclohexylbenzene hydroperoxide, is separated by first catalytically hydrogenating selectively the phenol in the mixture, resulting in a mixture of cyclohexylbenzene, which is unchanged, and cyclohexanone; the thus obtained mixture is subjected to fractional distillation to obtain cyclohexylbenzene which can be returned as to a process for the production of cyclohexylbenzene hydroperoxide, and cyclohexanone.

Abstract: A process for purifying aromatic hydrocarbons contained in liquid products of refining petroleum fractions or liquid products of coal coking or low-temperature carbonization from non-aromatic hydrocarbons which comprises heat-treatment of said liquid products at a temperature ranging from 750.degree. to 950.degree. C. under a pressure within the range of from 1 to 10 atm in the presence of acyclic C.sub.2 -C.sub.4 hydrocarbons employed separately or in various combinations at a weight ratio between said acyclic hydrocarbons and said liquid products being of at least 0.3. The heat-treatment results in a vapor-gas mixture which is cooled to isolate a condensate containing predominantly aromatic hydrocarbons. The process is technologically simple and makes it possible to purify aromatic hydrocarbons practically without decomposition thereof.