US3849261A - Method for separating hydrocarbons especially aromatic hydrocarbons and installations therefor - Google Patents

Method for separating hydrocarbons especially aromatic hydrocarbons and installations therefor Download PDF

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US3849261A
US3849261A US00229273A US22927372A US3849261A US 3849261 A US3849261 A US 3849261A US 00229273 A US00229273 A US 00229273A US 22927372 A US22927372 A US 22927372A US 3849261 A US3849261 A US 3849261A
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G Gau
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Bpifrance Financement SA
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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C7/00—Purification; Separation; Use of additives
    • C07C7/04—Purification; Separation; Use of additives by distillation
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C7/00—Purification; Separation; Use of additives
    • C07C7/148—Purification; Separation; Use of additives by treatment giving rise to a chemical modification of at least one compound
    • C07C7/173—Purification; Separation; Use of additives by treatment giving rise to a chemical modification of at least one compound with the aid of organo-metallic compounds

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  • ABSTRACT The method and installation are for the enrichment of one of the constituents of an initial mixture containing at least two hydrocarbons, especially with neighboring boiling points, and of which one at least possesses molie hydrogens, Fractional distillation of this mixture is effected in contact with a phase containing an organometallic compound derived from a compound having itself mobile hydrogens and in which the metallic atoms are substituted in reversible manner for these mobile hydrogens.
  • the vapor phase enriched in the hydrocarbon of the initial mixture which has the least affinity for metallic atoms is collected and an unvaporised phase enriched in the hydrocarbon of the initial mixture which has the most affinity for metallic atoms in partially metalled form is also produced.
  • the affinity of the hydrocarbons concerned for the metallic atoms varies sometimes considerably from one hydrocarbon to the other and from one isomer to the other. By conducting operations continuously and in countercurrent in a distillation column relatively few stages suffice to obtain efficient separation of the hydrocarbons.
  • the transmetallation reactions are facilitated by basic catalysts such as tertiary amines and chelating polyamines.
  • the invention relates to a method for separating hydrocarbons especially aromatic hydrocarbons and to an installation therefor. More particularly the invention relates to a method of separating hydrocarbons of which at least one possesses mobile hydrogens, from mixtures which contain them, especially from mixtures of hydrocarbons of which at least one is aromatic, and it relates more especially, since it is in this case that its application seems to offer the most advantage, but not exclusively, to a method of separating those hydrocarbons which have neighboring boiling points such as, for example, isomeric hydrocarbons.
  • hydrocarbons of which the separation often assumes very great importance for the chemical industry, belong for example the various xylenes (ortho-, metaand paraxylenes) and ethylbenzene, which are available in large quantities in the form of their mixtures.
  • the method according to the invention for enriching in one of its constituents an initial mixture containing at least two hydrocarbons, especialy with neighboring boiling points, and of which at least one possesses mobile hydrogens is characterised in that fractional distillation of this mixture in contact with a phase containing an organo-metallic compound derived from a compound having itself mobile hydrogens and in which the metallic atoms are substituted in reversible manner for these mobile hydrogens is carried out, and in that there is collected, on one hand, the vapor phase enriched in the hydrocarbon of the initial mixture which has the least afiinity for metallic atoms and, on the other hand, an unvaporised phase enriched in the hydrocarbon of the initial mixture which has the most affinity for metallic atoms in partially metallated form.
  • the method according to the invention takes advantage of the fact that, on one hand, organo-metallic compounds of the type concerned give rise to equilibrium reactions with that or those of the hydrocarbons of the mixture which possess mobile hydrogens, a portion of the latter exchanging reversibly with the metallic atoms of the organo-metallic compound and, on the other hand, the affinity of the hydrocarbons concerned for these metallic atoms varies sometimes considerably, from one hydrocarbon to the other, and from one isomer to the other.
  • organo-metallic compounds considered are not addition products of metals with hydrocarbons, but substitution compounds of these metals for mobile hydrogens of these hydrocarbons.
  • the metals which are well suited for these organometallic compounds, due especially to the speed of the exchange reactions that they provide, are lithium, sodium and potassium, the other alkali metals being prohibitive in price, even in the laboratory.
  • These organometallic compounds can be manufactured from any compounds possessing mobile hydrogens.
  • aromatic tertiary amines such as N,N-dimethylaniline, which include in their nuclei hydrogen atoms capable of being substituted by metallic atoms, or with aromatic hydrocarbons, such as isopropylbenzene, isobutylbenzene, trimethyl-l,2,4 benzene, trimethyl-l,2,3 benzene, trimethyl-l,3,5 benzene and other polyalkylbenzenes.
  • the reaction can be carried out either in a homogeneous liquid phase, or in the mass with a solid organometallic compound: the organo-metallic compounds hence can be, either completely, or partially solubilized in the reaction liquid medium.
  • the transmetallation reaction hence occurs on the plates and this, either in the midst of the liquid phase, if the reaction is carried out in a homogeneous phase, or partially or completely in the midst of the solid phase, if the reaction is carried out in a heterogeneous phase. In the latter case, the finely divided solid is kept in suspension in the liquid by the turbulence created by the plates to improve the liquidvapor contact.
  • the transmetallation reactions are advantageously carried out in the presence of basic catalysts which facilitate, especially accelerate these reactions.
  • These catalysts must be stable toward the organo-metallic compounds.
  • a first group of these catalysts formed by tertiary amines in which the groups attached to the nitrogen atoms are alkyl or cycloalkyl groups.
  • Nontertiary amines cannot be used, since the hydrogens connected to their nitrogen atoms would always be more mobile than the hydrogens of the hydrocarbons to be separated, so that they would metallate pref erentially to the hydrocarbons.
  • tertiary amines which are well suited, there may be mentioned, for instance, triethylamine, tripropylamine,- tributylamine, N,N-dimethylcyclohexylamine, or bridged amines such as triethylenediamine or quinuclidine.
  • basic catalysts of a second group which, at the same time, are adapted to form chelates with the metallic atoms of the organo-metallic compounds.
  • These basic catalysts are constituted by tertiary dior polyamines in which the groups attached to the nitrogen atoms are alkyl or cycloalkyl groups, and in which two at least of their nitrogen atoms are sufficiently close to one another to permit the formation of chelates.
  • tertiary diamines or polyamines enable at the same time the acceleration of the speed of the reactions, the considerable increase in the solubility of the organometallic compounds and the regulation of the progress of these reactions.
  • organo-metallic compounds which can be associated with organo-metallic compounds and which contain oxygen (ethers) or phosphorus (phosphines) cannot be used since they are destroyed by organoalkali compounds of the type concerned.
  • chelating diamines As examples of chelating diamines, the following products may be mentioned: N,N,N',N'-tetraalkylethylene-diamine; N.N,N',N'-tctraalkylpropylenediamine; N,N,N,N-tetraalkyl-1.2-.
  • alkyl groups being selected from among the methyl, ethyl, propyl or butyl groups.
  • R and R are methyl, ethyl, propyl, isopropyl, nbutyl, s-butyl, t-butyl or cyclohexyl groups, enable good results to be obtained.
  • polyamines may be used:
  • N,N,N,N'-tetramethyll ,Z-diamino-cyclohexane whose chelating power is comparable with that of N,N,- N,N-tetramethylenediamine, but whose volatility is less and chemical stability greater.
  • the oraganometallic compounds chelated by this diamine are very soluble in N,N'-dimethylaniline and the metallation, especially in installations which will be described below, can be carried out in a homogeneous phase.
  • N,N,N ,N '-tetramethyl-1 ,2-diaminocyclohexane can be obtained by methylation of l,2-diaminocyclohexane with formaldehyde and with formic acid according to the method of Eschweiller and Clarke.
  • Recourse may advantageously also be had to a solvent which enables, either the solution (partial or complete) of the organo-metallic compound to be facilitated, or its carrying in the form 'of a finely divided suspension to be facilitated.
  • It can be constituted by an excess of the mobile hydrogen compound from which the organo-metallic compound used is derived. It can also be constituted by any medium stable to organo-metallic compounds and to metallation. Ethers are not suitable since they are not stable in the presence of organo-alkali compounds.
  • the solvent for example, could be constituted by aromatic hydrocarbons of weak acidity, such as cumene, tertiobutylbenzene, isobutylbenzene or diisopropylbenzene.
  • aromatic hydrocarbons of weak acidity such as cumene, tertiobutylbenzene, isobutylbenzene or diisopropylbenzene.
  • One of the preferred solvents is constituted by tertiobutylbenzene, whose chain cannot be metallated.
  • gas-oil fractions can also be used, especially in the petroleum industry, gas-oil fractions.
  • the solvent can also be constituted, especially when greater solubilization of the organo-metallic compound is desired, by a more polar and/or more solubilizing me dium, such as N,N-dimethylaniline, N,N-dimethylcyclohexylamine or any other tertiary amine.
  • a more polar and/or more solubilizing me dium such as N,N-dimethylaniline, N,N-dimethylcyclohexylamine or any other tertiary amine.
  • the reactive species are hence less reactive in the presence of symmetrical organomagnesiums and it is this which explains that the tertiary amines have less tendency to decompose by forming double bonds.
  • organometallic compounds can be effected in any manner known in itself. There could, for example, be prepared an organo-rnetallic compound of the formula R Na by proceeding as follows:
  • phenylsodium is prepared by causing very finely dispersed sodium to react with chlorobenzene introduced drop by drop at 20C.
  • the reaction takes place according to the scheme:
  • This first organo-metallic compound can be used to transmetallate the compound RH, for example NN- dimethylaniline; the benzene is entirely expelled from the phenylsodium by carrying out the reaction in a flask surmounted by a rectifiying column operating under reflux. To keep the boiling point relatively low, this operation is effected in partial vacuum.
  • the compound R Na is solubilized by the use of one of the aforesaid solubilizing basic catalysts and the insolubles are entirely removed by centrifugation.
  • the stabilizing organo-metallic compounds are either available commercially (example: Trialkylaluminium), or prepared by reactions similar to the following reactions:
  • FIGS. 1 to 3 show in diagrammatic manner various embodiments of installations enabling the application of the method, according to the invention.
  • FIG. I lends itself well to the pro- I duction, by a preferred first modification of the method according to the invention, of the separation of two hydrocarbons R I-I and R H, of which at least one possesses mobile hydrogens, from a mixture of the latter, by using an organo-metallic compound R Na derived from a compound with mobile hydrogens R H whose boiling point is above those of the hydrocarbons R,I-I and R H and which has a lesser affinity with respect to sodium than the two hydrocarbons R I-I and R l-l.
  • Procedure can be as follows or in similar manner:
  • RH and R H are, for example, constituted by paraxylene R ii and metaxylene R H respectively, and that R H is constituted, for example, by dimethylaniline, R Na then resulting by the substitution of one of the hydrogen atoms of its nucleus by sodium.
  • R,H could nonetheless just as well, for example, denote normal heptane (n-heptane) and R H toluene.
  • R l-l could also be constituted by another tertiary aromatic amine or by an aromatic hydrocarbon, such as cumene, isobutylbenzene, etc.
  • organo-sodium compound R Na could also be replaced by a corresponding organo-lithium compound R Li or organo-potassium compound R K or by mixtures of the latter.
  • FIG. 1 which comprises two distillation columns 2 and 4 of which the plates have been shown diagrammatically by horizontal rows 6 of interrupted lines.
  • a first column 2 there is charged respectively: at 8, into the middle of the column, the mixture of hydro carbons R I-I and R H to be separated;
  • metaxylene is more acid than paraxylene, which is itself more acid than N,N-dimethylaniline.
  • the dimethylaniline gives up practically all the sodium from its organo-metallic compound to the two xylenes and preferentially to the metaxylene.
  • the intake point 8 for the mixture of xylenes enables therefore the defining, as in any normal distillation, of the enrichment zone and the depletion zone of the column 2.
  • the intake point 10 can only be situated at some plates at the head of the column 2, the latter being sufficient to recover the slightly volatile compounds R l-l.
  • Paraxylene at a very high degree of purity is condensed at the head of the column, in a condenser 12. A portion of the condensate is sent back as reflux by a pipe 14, the other portion being collected through a pipe 16.
  • the mixture obtained at the base of the column 2 no longer contains paraxylene and the sodium is distributed between the metaxylene and the N,N- dimethylaniline according to the equilibrium (2).
  • This mixture is introduced, through a pipe 18, at a suitable height into a second distillation column 4, a portion of this mixture being, if necessary, taken off, vaporised in a reboiler 19 and reinjected into the base of the column 2.
  • the reverse reaction to the reaction (2) is produced, the equilibrium then being displaced toward the terms on the left of the equation, by vaporisation of the metaxylene.
  • the enrichment zone 22 is only used to stop the vapors of amine, of solvent and of R l-l.
  • the mixture obtained at the bottom of the column 'contains therefore the constituents introduced previ ously into the column 2, and can hence in principle be reused indefinitely and recycled to the intake point 10 of the column 2, through a pipe 29.
  • organo-metallic compound a portion of the organo-metallic compound is attacked by the traces of water or of sulfurized products present in the mixture of xylenes.
  • the purged mateial can be treated batchwise by distillation in vacuo, to recover the solvent as well as the undecomposed basic catalyst. After treating with water or with alcohol, the hydrocarbon R H is itself recovered and the sodium present in the purged material can be recovered in the form of soda.
  • R l-I which can be also N,N-dimethylaniline or cumene
  • R- H toluene
  • RH heptane
  • Ethylbenzene is slightly more volatile, but especially less reactive with respect to organo-sodium compounds than paraxylene.
  • the separation of the paraxylene and the ethylbenzene, on one hand, and metaxylene there can hence be produced, first of all, in the column 2 of the first unit, the separation of the paraxylene and the ethylbenzene, on one hand, and metaxylene, on the other hand, the paraxylene-ethylbenzene mixture being obtained at the head of column 2 in the vapor phase and the metaxylene being separated in the second column 4 of the first unit, as described above.
  • the separation of the paraxylene and of the ethylbenzene from the abovesaid vapor phase can then be carried out, after condensation of the latter, in the second aforesaid unit, after the introduction of the condensed mixture into the first column 2 of this second unit, at a point of the latter similar to the point 8 described above, the separation then taking place under conditions similar to those which have been described above with respect to the separation of paraxylene and metaxylene.
  • FIG. 2 There is shown in diagrammatic manner in FIG. 2, an installation in which the operations of distillation in the presence of organo-metallic compounds are carried out in columns 2a and 40 under partial vacuum, the operations of separating unmetalled compounds being effected in distinct columns 3a and a respectively, which operate at atmospheric pressure.
  • the mixture 8a of paraxylene and metaxylene is introduced at a suitable height into the column 2a whilst the phase containing the compound is introduced this time at the level of the upper plate 40, the liquid reflux being ensured either by a portion of the condensate 41, coming from the condenser 42 of the column 2a, or by the introduction of heavy products from the atmospheric column 3a, by means of a pipe 44, or by both simutaneously.
  • the condensate 41 of the first column contains paraxylene, compound R l-I liberated by the organometallic compound R Na and possibly solvent.
  • This modified installation enables in addition, if desired, the use of the reboiler 46 of the column 3a to produce the vapor necessary for the operation of the column 2a, this vapor being brought to the base of the column 2a by means of the pipe 48.
  • The-portion of the installation serving for the regeneration of the compound R Na and for the purification of the metaxylene operate in a manner similar to that which has just been described.
  • the mixture of metaxylene, of the mobile hydrogen compound from which the organo-metallic compound R Na is derived, and of their metallated forms, which is drawn off from the base of the column 2a is introduced at the level of the upper plate 50 of the regeneration column 4a under partial vacuum, by means of a pipe 52.
  • the regenerated organo-metallic compound, withdrawn from the base of the regeneration column 4a, is recycled, by means of a pipe 53, to the intake point 40 of the column 2a, whilst the vapor phase 54, containing a mixture of metaxylene and R H which escapes from the top of the column 40 subjected, after condensation in a condenser 55, to fractional distillation in the column 5a, operating at atmospheric pressure.
  • the purified metaxylene is then collected at 56 from the vapor phase, whilst the compound R H withdrawn from the base of the column 5a is recycled to the level of the upper plate 50 of the column 4a.
  • the reboiler 57 associated with the column 5a supplies the necessary vapor for the operation at the same time of the column 5 and of the column 4a, by means of pipes 58 and 59.
  • FIG. 3 shows diagrammatically an installation in which the latter modification of the method according to the invention can be applied.
  • This installation comprises a column 2b, operating preferably under reduced pressure, in which the mixture of hydrocarbons R I-I and R H introduced into this column at a point 8b, flows in countercurrent with a phase containing the organo-metallic compound introduced at a point 1% of the same column, above the point 8b.
  • the vapor phase obtained at the head of the column 2b which contains the compound R H and least acid hydrocarbon R H.
  • After condensation in a condenser 60, it is fractionated in its turn in a separate column 3b operating under atmospheric pressure, R H being withdrawn at 62 from the bottom of the column 3b.
  • the regeneration column 4b supplied, through a pipe 64, with products withdrawn from the bottom of the column 2b, delivers at its head a vapor phase containing a mixture of the compound R il and of the other hydrocarbon R H.
  • This mixture is, after condensation in a condenser 66, fractionated in its turn in a separate column 5b operating at atmospheric pressure, R H being there again withdrawn at 68 from the bottom of this column 5b.
  • the regeneration in the column 4b will be facilitated by the introduction of an excess of the compound R H at the bottom of the column 4b and by its relatively high acidity.
  • the reboiler 70 of the column 4b and there can be introduced in vapor form into the bottom of the column 4b the amount of the compound R H necessary to assure the operation of the column 4b and the entrainment in the vapor phase of the whole of the compound R H con- .tained in the mixture introduced into this column by means of the pipe 64.
  • These amounts of R l-l in vapor form can especially come, by means of a pipe 72, from the head fractions of the columns 3b and 5b and/or from a separate source shown diagrammatically at 74.
  • the two principal columns 2a and 4b can also be supplied at their respective bases with solvent contained in the phase carrying the organo-metallic compound, when this solvent possesses itself a volatility higher than that of the hydrocarbons to be separated and a very weak acidity.
  • EXAMPLE 1 0.05 Moles of phenylsodium is solubilized in a mixture of 50 cm3 (0.39 moles) of N,N-dimethylaniline and 20 cm3 (0.153 moles) of N,N,N,N'-tetramethylethylenediamine.
  • the sodium is immediately distributed by equilibrium of metallation between the benzene and the dimethylaniline; the dimethylaniline being slightly more acid than the benzene and occurring in a higher concentration takes the largest portion of the sodium.
  • the medium is brought to 50C and at zero time, there is added:
  • the temperature is kept at 50C and, 15 minutes after the addition of the xylenes (at time t 15 min) there is taken off, by vacuum distillation, and condensed a small fraction of which the composition is substantially representative of that of the vapor in equilibrium with a liquid present in the flask at the moment of the withdrawal.
  • Metaxylene 79% which corresponds therefore to a separation coefficient between the gaseous and liquid phase of:
  • EXAMPLE 4 The same operational conditions as in Example 1 are used but N,N,N',N'-tetramethylethylenediamine is not added; the organo-metallics are not soluble in the liquid phase and the attack on the solid phenylsodium progresses slowly. At zero time there is added;
  • the separation coefficient C develops as a function of time, as emerges from the following Table, in which there is indicated the measured values of the separation coefficient after increasing reaction times.
  • EXAMPLE 5 0.05 Moles of phenylsodium are mixed with 50 cm3 (0.39 moles) of N,N-dimethylaniline and 80 cm3 (0.58 moles) of triethylamine.
  • the temperature is controlled at 40C and at zero time, there is added:
  • reaction speed is more rapid than in the preceding case, which is due to the fact that the triethylamine is a good basic catalyst of the reaction.
  • EXAMPLE 6 This example shows that there is a reduction in the separation coeffecient when the reaction time is very long. This reduction is observed for the heterogeneous reaction and also for the homogeneous reaction, as is indicated by the following figures:
  • the temperature is controlled at 40c, and at zero time, there is added:
  • EXAMPLE 9 The method is carried out under the same operational conditions as in Example 1, but in the presence of 0.05 moles of phenylsodium and of 0.0125 moles of Mg (C H obtained by the action of the phenylsodium on phenylmagnesium bromide.
  • the ratio of the concentrations of the unmetallated xylenes in the liquid phase was equal to the ratio of the concentrations of the xylenes in the vapor phase.
  • EXAMPLE 1 3 0.05 Moles of phenylsodium, 50 ml of t-butylbenzene and 0.05 moles of N,N,N',N'-tetramethyl-1,2- diaminocyclohexane were mixed.
  • the separation coefficient did not vary as a function of time and is equal to:
  • This value corresponds also to K, 9.5, the constant determined by treatment of the liquid with dimethylsulfate, the t-butylbenzene not being metallated under these conditions.
  • EXAMPLE 14 0.05 Moles of phenylsodium, 50 ml of t-butylbenzene and 0.05 moles of N,N,N,N'-tetramethyl-1,2- diaminocyclohexane are mixed.
  • the temperature is controlled at 40C and at time EXAMPLE 15 0.05 Moles of phenylsodium, 50 ml of tbutylbenzene, 0.05 moles of N,N,N,N'-tetramethyl- 1,2-diaminocyclohexane are mixed.
  • the separation coefficient obtained between the para and metaxylene is The equilibrium constant K is equal to 9.5, this corresponding to the equilibrium of the pseudocumene and of the metaxylene, in the presence of the organoalkyli compound, is equal to 2.6.
  • the alkali cation plays a preponderant role, the measured values of K being substantially independent of the R group in the corresponding organo-metallic compound, of the basic catalysts or chelating diamines used.
  • the relative acidity of the meta compounds with respect to the para compounds is much greater with the organo-potassiums than with the organo-sodiums.
  • Ethylbenzene is less acid than paraxylene in the transmetallation with sodium;
  • Method of enriching one of the constituents of an initial mixture containing at least two hydrocarbons, and of which at least one possesses a replaceable hydrogen atom more readily replaceable by a metal of an organometallic compound than a hydrogen atom of the other hydrocarbon comprising fractionally distilling said mixture in contact with such an organo-metallic compound having a metal atom which preferentially replaces a replaceable hydrogen atom on one of said hydrocarbons, said metal atom being substituted in a chemically reversible manner for said replaceable hydrogen atoms, effecting replacement of at least one hydrogen atom of said hydrocarbon whose hydrogen atom is more readily replaced by said metal atom with said metal atom, and collecting vapor phase distillate enriched in the hydrocarbon of the initial mixturewhich has the least affinity for said metal and an unvaporized bottoms phase enriched in the hydrocarbon of the initial mixture which has the most affinity for said metal atom in a partially metallated form.
  • organometallic compound-1 alkali compound derived from an aromatic hydrocarbon or from an aromatic 9.
  • organo' metallic compound is an organo-alkalicompound derived from trimeffiyl-1,2,4' benzene, from trime'thyl- 1,2,3 benzene or from trimethyl-1,3,5 benzene.
  • organo-metallic compound which is brought into contact with the mixture of hydrocarbons to be separated is in the form of a dispersion a solvent substantially unable to undergo metallation itself and resistant to the action of the organo-metallic compounds.
  • said solvent is constituted by a saturated hydrocarbon or by an aromatic hydrocarbon such as cumene, isobutylbenzene, tertiobutylbenzene or diisopropylbenzene.
  • phase containing the organo-metallic compound which is brought into contact with the mixture of hydrocarbons to be separated is constituted by a solution or a dispersion of this organo-metallic compound in an excess of the compound with mobile hydrogens from which it is derived.
  • said dispersion also contains a basic catalyst constituted by a tertiary amine in which the groups fixed to the nitrogen atom are alkyl or cyclo-alkyl groups.
  • tertiary amine is a tertiary monoamine such as triethylamine, tripropylamine, tributylamine, N,N-dimethylcyclohexylamine or a bridged amine such as triethylenediamine or quinuclidine.
  • the dispersion contains a chelating agent constituted by a polyamine in which the amine groups are tertiary and the hydrocarbon groups fixed on their nitrogen atoms or connecting the latter are saturated, the nitrogen atoms of at least two of these amines being sufficiently close to one another to permit the formation of chelates with the metallic atoms of the abovesaid organometallic compound.
  • a chelating agent constituted by a polyamine in which the amine groups are tertiary and the hydrocarbon groups fixed on their nitrogen atoms or connecting the latter are saturated, the nitrogen atoms of at least two of these amines being sufficiently close to one another to permit the formation of chelates with the metallic atoms of the abovesaid organometallic compound.
  • the chelating agent is constituted by a diamine selected from the group consisting of N,N,N,N'-tctraalkylethylenediamine, N,N,N ',N'-tetraalkyll ,2-
  • alkyl groups being selected from the groups methyl, ethyl, propyl and butyl,
  • the chelating agent is constituted by N,N,N,N-tetramethyl- 1 ,2-diaminocyclohexane.
  • R is an alkyl or aryl group.
  • Method according to claim 2 to produce the fractionation of said mixture of hydrocarbons wherein the placing in contact of the initial mixture to be separated with the phase containing said organo-metallic compound is effected in several stages in countercurrent in a distillation column, the organo-metallic compound being introduced into the column, at a sufficient number of stages above the intake point of the mixture to be fractionated for the vapor phase obtained at the level of the intake point of the organo metallic compound to be substantially free of the hydrocarbon which has greatest affinity for metallic atoms and at a number of stages below the top of the column sufficient to enable the practically complete separation of the hydrocarbon with the least affinity for metallic atoms.
  • Method according to claim 2 for effecting the fractionation of said mixture of hydrocarbons wherein the placing in contact of this mixture with the phase containing said organo-metallic compound is effected in several stages and in countercurrent in a first distillation column operating under partial vacuum, the phase containing the abovesaid organo-metallic compound being introduced into the upper portion of this first column and the mixture of hydrocarbons being introduced into this first column at a point situated below this upper portion at a sufficient number of stages for the vapor phase obtained at the head of the column to be practically free of the hydrocarbon of the initial mixture which has the most affinity for metallic atoms, collecting and condensing this vapor phase, proceedinging to a fractional distillation of at least a portion of the condensate in a second column operating at atmospheric pressure to collect at the head the hydrocarbon which has the least affinity for metallic atoms, and vaporising and recycling a portion at least of the tail products of this second column in the lower portion of the first column.
  • organo-metallic compound is derived from a mobile hydrogen compound which possesses an affinity for the corresponding metal higher than those of the hydrocarbons to be separated and is constituted by a liquid whose boiling point is lower than those of these hydrocarbons.
  • Method according to claim 28 wherein said placing in contact is effected in several steps in countercurrent in a fractionating column, collecting and condensing the vapor phase obtained at the head of the column, and proceedinging to a fractional distillation of a portion at least of the condensate to collect said hydrocarbon to be separated.
  • Method according to claim 29 wherein the unvaporised phase withdrawn from the base of said column is subjected to a fractional distillation in a second fractionating column, in the presence of an excess of said mobile hydrogen compound sufficient to entrain in the vapor phase the hydrocarbon of the initial mixture which has most affinity for metallic atoms, collecting the vapor phase, condensing a portion at least of this vapor phase and subjecting it to fractional distillation to separate said last mentioned hydrocarbon.
  • organo-metallic compound is constituted by an organolithium, organo-sodium or organo-potassium compound.
  • phase containing the organo-metallic compound is introduced into said first fractionating column in the form of a dispersion or of a solution in a solvent substantially unable itself to undergo metallation and resistant to the action of the abovesaid organo-metallic compounds.
  • phase containing the organo-metallic compounds contains also a chelating agent constituted by a diamine selected from the group consisting of N,N,N,N-tetraalkyl-ethylenediamine, N,N,N,N'-tetraalkyl-l ,2- diaminocyclohexane, the alkyl groups selected being the methyl, ethyl, propyl or butyl groups.
  • a chelating agent constituted by a diamine selected from the group consisting of N,N,N,N-tetraalkyl-ethylenediamine, N,N,N,N'-tetraalkyl-l ,2- diaminocyclohexane, the alkyl groups selected being the methyl, ethyl, propyl or butyl groups.
  • phase containing the organo-metallic compound contains also a chelating agent constituted by a polyarnine of the general formula:
  • R and R are constituted by the methyl, ethyl, propyl, isopropyl, n-butyl, s-butyl, t-butyl or cyclohexyl groups.
  • organometallic compound is in the form of a dispersion which contains an additional organo-metallic compound of the formula:
  • R is an alkyl or aryl group.
  • organo-metallic compound is an organo-alkali compound selected from the group consisting of an organolithium, an organo-sodium and an organo-potassium compound.
  • organo-metallic compound is in the form of a solution which contained an additional organo-metallic compound of the formula in which R is an alkylor aryl group.
  • polyamine in which the amine groups are tertiary and the hydrocarbon groups fixed on the nitrogen atoms or connecting the latter are saturated, the nitrogen atoms of at least two of these amines being sufficiently close to one another to permit the formation of chelates with the metallic atoms of said organo-metallic compound.

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  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
US00229273A 1971-02-26 1972-02-25 Method for separating hydrocarbons especially aromatic hydrocarbons and installations therefor Expired - Lifetime US3849261A (en)

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AT (1) AT326626B (it)
BR (1) BR7201063D0 (it)
CA (1) CA992489A (it)
DD (1) DD99981A5 (it)
DE (1) DE2208115C3 (it)
ES (1) ES400659A1 (it)
FR (1) FR2127175A5 (it)
GB (1) GB1378951A (it)
IE (1) IE36118B1 (it)
LU (1) LU64839A1 (it)
NL (1) NL7202516A (it)
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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5198594A (en) * 1991-11-27 1993-03-30 Amoco Corporation Alkylation of alkylaromatics promoted by sonicated alkali metal
US20050263385A1 (en) * 2004-06-01 2005-12-01 Bayer Materialscience Ag Process for the distillative separation of aqueous amine solutions
CN107324967A (zh) * 2016-04-28 2017-11-07 上海华谊工程有限公司 一种从混合二甲苯中分离对二甲苯的工艺
KR20190079385A (ko) * 2017-12-27 2019-07-05 한화케미칼 주식회사 탄화수소 함유 용액 내의 방향족 함량의 측정 방법
CN110437024A (zh) * 2018-05-04 2019-11-12 阿克森斯公司 用于在真空下分离芳族化合物的方法和装置

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB803558A (en) * 1955-02-10 1958-10-29 Ziegler Karl Process for purifying hydrocarbons, especially olefines
US2959626A (en) * 1957-07-15 1960-11-08 Cosden Petroleum Corp Process for the production of styrenegrade ethyl benzene
US3177234A (en) * 1962-05-31 1965-04-06 Labofina Sa Nickel werner complexes of alphaarylalkylamines
US3254024A (en) * 1965-03-03 1966-05-31 Halcon International Inc Process for separating c8-aromatic hydrocarbons by series column distillation
US3356593A (en) * 1965-08-17 1967-12-05 Chevron Res Separation of metaxylene-paraxylene mixtures by extractive distillation
US3598879A (en) * 1968-12-19 1971-08-10 Ashland Oil Inc Alkyl transfer of alkyl aromatics with group i-a,ii-a,iv,or rare earth metals on boria alumina
US3629288A (en) * 1969-11-06 1971-12-21 Nat Patent Dev Corp Purification of aprotic solvents
US3707577A (en) * 1971-03-08 1972-12-26 Exxon Research Engineering Co Separation of aromatics

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB803558A (en) * 1955-02-10 1958-10-29 Ziegler Karl Process for purifying hydrocarbons, especially olefines
US2959626A (en) * 1957-07-15 1960-11-08 Cosden Petroleum Corp Process for the production of styrenegrade ethyl benzene
US3177234A (en) * 1962-05-31 1965-04-06 Labofina Sa Nickel werner complexes of alphaarylalkylamines
US3254024A (en) * 1965-03-03 1966-05-31 Halcon International Inc Process for separating c8-aromatic hydrocarbons by series column distillation
US3356593A (en) * 1965-08-17 1967-12-05 Chevron Res Separation of metaxylene-paraxylene mixtures by extractive distillation
US3598879A (en) * 1968-12-19 1971-08-10 Ashland Oil Inc Alkyl transfer of alkyl aromatics with group i-a,ii-a,iv,or rare earth metals on boria alumina
US3629288A (en) * 1969-11-06 1971-12-21 Nat Patent Dev Corp Purification of aprotic solvents
US3707577A (en) * 1971-03-08 1972-12-26 Exxon Research Engineering Co Separation of aromatics

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5198594A (en) * 1991-11-27 1993-03-30 Amoco Corporation Alkylation of alkylaromatics promoted by sonicated alkali metal
US20050263385A1 (en) * 2004-06-01 2005-12-01 Bayer Materialscience Ag Process for the distillative separation of aqueous amine solutions
US7575660B2 (en) * 2004-06-01 2009-08-18 Bayer Materialscience Ag Process for the distillative separation of aqueous amine solutions
CN107324967A (zh) * 2016-04-28 2017-11-07 上海华谊工程有限公司 一种从混合二甲苯中分离对二甲苯的工艺
KR20190079385A (ko) * 2017-12-27 2019-07-05 한화케미칼 주식회사 탄화수소 함유 용액 내의 방향족 함량의 측정 방법
CN110437024A (zh) * 2018-05-04 2019-11-12 阿克森斯公司 用于在真空下分离芳族化合物的方法和装置

Also Published As

Publication number Publication date
BR7201063D0 (pt) 1973-09-25
SE373122B (it) 1975-01-27
IE36118B1 (en) 1976-08-18
DE2208115A1 (de) 1972-09-07
SU460612A3 (ru) 1975-02-15
RO64224A (fr) 1979-06-15
AT326626B (de) 1975-12-29
NL7202516A (it) 1972-08-29
DD99981A5 (it) 1973-09-05
ES400659A1 (es) 1975-06-16
ATA154172A (de) 1975-03-15
FR2127175A5 (it) 1972-10-13
LU64839A1 (it) 1972-12-05
DE2208115B2 (de) 1975-03-20
GB1378951A (en) 1975-01-02
ZA721185B (en) 1972-11-29
DE2208115C3 (de) 1975-10-30
CA992489A (en) 1976-07-06
IE36118L (en) 1972-08-26

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