Abstract: Methods and apparatuses for separating toluene from multiple hydrocarbon streams are provided. A method includes fractionating a first hydrocarbon stream, which includes benzene-depleted fractionation bottoms from benzene fractionation, in a first fractionation zone into a first fractionation overhead stream that includes toluene and a first fractionation bottoms. A second hydrocarbon stream, which includes toluene and is substantially free of compounds having a higher vapor pressure than toluene, is fractionated in a second fractionation zone into a second fractionation overhead stream including toluene and a second fractionation bottoms. The second fractionation zone is in liquid isolation from and in vapor communication with the first fractionation zone. The first fractionation bottoms are removed from the first fractionation zone, and the second fractionation bottoms are removed from the second fractionation zone separate from the first fractionation bottoms.

Abstract: The invention relates to a method for extracting styrene, having a polymerization quality, from pyrolysis benzol fractions containing styrene by means of extractive distillation. The pyrolysis benzol fraction is separated in a separating wall column in a C8-core fraction, a C7 fraction and a C9+-fraction, the obtained C8-core fraction is subjected to selective hydrogenation of the phenylacetylene C8H6 which it contains. Subsequently, the obtained C8-fraction undergoes extractive-distillative separation in a styrene fraction and a fraction which is low in styrene.

Abstract: Methods and systems for controlling the pressure of distillation columns, for example those operating under vacuum pressure and conventionally equipped with a steam ejector system, are described. Representative distillation columns are used in the separation of thermally unstable components, such as the physical solvent sulfolane, having relatively low volatility. Such columns are employed in aromatic hydrocarbon extraction processes for the recovery of purified C6-C8 aromatic hydrocarbons from a hydrocarbon feed stream (e.g., obtained from the catalytic reforming of naphtha).

Abstract: A method and an apparatus (7?) for separating 1,2,4-Trimethylbenzene by fractional distillation of a mixture (31) that contains C9 or C9+ aromatic hydrocarbons, and possibly hydrocarbons with less nine nine carbon atoms. In an aspect of the invention, a first distillation step and a second distillation step are carried out in respective distillation chambers (75, 75?) defined by a cylindrical vertical container 501 and by an inner partition wall (85) of the container.

Abstract: In various embodiments, the present disclosure describes processes and systems for recovery of styrene from a styrene-rich feedstock. The processes and systems maintain performance of an extractive solvent used in the styrene recovery. In general, the processes include introducing a styrene-rich feedstock to an extractive distillation column, removing a styrene-rich stream from the extractive distillation column, introducing the styrene-rich stream to a solvent recovery column, removing a styrene-lean stream from the solvent recovery column, separating and treating a portion of the styrene-lean stream to form a treated extractive solvent and recycling the treated extractive solvent. In some embodiments, the treating process also includes steam stripping. Styrene-recovery systems including an extractive distillation column, a solvent recovery column, a solvent treatment apparatus having at least one equilibrium stage and a continuous circulation loop connecting these components are also disclosed herein.

Abstract: A method for the separation of hydrocarbon compounds utilizing a dividing wall distillation column is described. The dividing wall distillation column enables one or more side draw stream to be removed from the dividing wall distillation column in addition to an overhead stream and a bottoms stream.

Abstract: In various embodiments, the present disclosure describes processes and systems for recovery of styrene from a styrene-rich feedstock. The processes and systems maintain performance of an extractive solvent used in the styrene recovery. In general, the processes include introducing a styrene-rich feedstock to an extractive distillation column, removing a styrene-rich stream from the extractive distillation column, introducing the styrene-rich stream to a solvent recovery column, removing a styrene-lean stream from the solvent recovery column, separating and treating a portion of the styrene-lean stream to form a treated extractive solvent and recycling the treated extractive solvent. In some embodiments, the treating process also includes steam stripping. Styrene-recovery systems including an extractive distillation column, a solvent recovery column, a solvent treatment apparatus having at least one equilibrium stage and a continuous circulation loop connecting these components are also disclosed herein.

Abstract: Use of mordenite zeolite and zeolite Y as adsorbents enables a dimethylnaphthalene isomer mixture to be efficiently separated. A feedstock oil containing a dimethylnaphthalene isomer mixture including an ?,?-isomer, an ?,?-isomer, and a ?,?-isomer is passed through an adsorbent layer (A) including mordenite zeolite together with a developing solvent. Subsequently, a liquid discharged from the adsorbent layer (A) is passed through an adsorbent layer (B) including zeolite Y. An eluent is passed through the adsorbent layer (B). The solvent is removed from the resultant eluate to obtain the ?,?-isomer of dimethylnaphthalene. Similarly, the ?,?-isomer of dimethylnaphthalene is obtained from the adsorbent layer (A).

Abstract: The present invention is directed to an apparatus and method for the distillation of a readily polymerizable vinyl aromatic compound employing a polymerization inhibitor. The vinyl aromatic compound is subjected to distillation in at least one fractionation column having at least one reboiler for maintaining the bottoms of said column at a proper temperature. The reboiler includes a heating section and a vapor phase section. The bottoms fraction from the fractionation column is cycled to the reboiler and subjected to heat to vaporize at least a portion of the bottoms fraction to form a vapor phase in the vapor section, A slip stream of the bottoms fraction is introduced to the vapor phase section of the reboiler. The slipstream contains polymerization inhibitor that had been added to the process at the fractionation column. The invention reduces fouling at the reboilers. The slipstream is optionally introduced to the reboiler using one or more spray nozzles.

Abstract: Methods and compositions for improving the extraction of phenols from crude styrene using an aqueous caustic solution are disclosed. It has been discovered that aromatic or alkylammonium tailed multi-polyether headed surfactants and/or quaternary polyamines will improve this extraction, particularly in propylene oxide styrene monomer systems.

Abstract: Disclosed is a process for recovering styrene from a feedstock containing at least styrene, ethylbenzene, and one or more aromatic or non-aromatic hydrocarbon compounds which includes separating said feedstock into a first stream relatively more concentrated in styrene than said feedstock and a second stream relatively more concentrated in ethylbenzene than said feedstock, recovering styrene from said first stream to produce a styrene product stream, dehydrogenating the ethylbenzene of said second stream to produce additional styrene, and recovering said additional styrene. The feedstock may be separated into said first and second streams by a process selected from the class consisting of extractive distillation, azeotropic distillation, distillation, liquid-liquid extraction, chemical complex formation, membrane separation, and combinations thereof, and the additional styrene may be recovered by recycling it into said feedstock.

Abstract: An extractive distillation process for separating at least one substituted unsaturated aromatic from a pyrolysis gasoline mixture, containing said aromatic and at least one close-boiling aromatic or non-aromatic hydrocarbon, employing a two part extractive solvent, the first part selected from propylene carbonate, sulfolane (tetramethylene sulfone), methyl carbitol, 1-methyl-2-pyrrolidinone, 2-pyrrolidinone and mixtures thereof, and the second portion consisting of water.

Abstract: p-Cymene and p-menthane are difficult to separate one from another by conventional distillation or rectification because of the close proximity of their boiling points. p-Cymene and p-menthane can be readily separated one from another by using azeotropic or extractive distillation. Typical examples of effective agents, for azeotropic distillation: diethyelene glycol ethyl ether, 1-pentanol and isobutanol; for extractive distillation: butyl benzoate, undecyl alcohol and methyl benzoate.

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: 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: A method of separating 2,6-dimethylnaphthalene from a feed material containing a mixture of dimethylnaphthalene isomers comprises the steps of:adsorption separation using an adsorbent of a zeolite Y containing alkali metal or zinc and a desorbent of an organic solvent mainly composed of paraxylene and/or orthoxylene to obtain a solution consisting of the desorbent and the feed material containing 2,6-dimethylnaphthalene at a concentration of at least 60 wt % on the feed material other than desorbent; andcrystallization of the solution having a concentration of the desorbent at 30 to 90 wt % to obtain 2,6-dimehtylnaphthalene of high purity in a crystalline form.

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: 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: 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: Residual products obtained in the catalytic dehydration of alpha-methylbenzyl alcohol are treated to recover monomeric styrene values by a process which comprises fractionally distilling the residual products in two stages under different temperature and time conditions.

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: 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 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.

Abstract: A process for dehydrating an essentially one-phase wet solvent stream obtained in a solvent dewaxing-solvent deoiling process, which solvent stream contains at least 60% toluene with the balance being water and methyl ethyl ketone (hereinafter MEK), is dehydrated by (a) fractionally distilling to produce a bottom fraction of anhydrous MEK-toluene solvent and an overhead fraction containing all the water originally present in the wet solvent stream; (b) condensing and separating said overhead fraction into a toluene-containing, water-lean phase, which is used as reflux in step (a), and a toluene-free, MEK-containing, water-rich phase; (c) extracting into a hydrocarbon stream some MEK from said water-rich phase and from the condensed azeotropic mixture recycled from step (g) hereinafter; (d) recovering from step (c) a second water-rich stream, which water-rich stream contains the MEK not extracted into said hydrocarbon stream; (e) azeotropically distilling said second water-rich stream so as to obtain water as