EP1496099B1 - improved isomerisation process of a C7 fraction with naphthenic rings opening - Google Patents

improved isomerisation process of a C7 fraction with naphthenic rings opening Download PDF

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Publication number
EP1496099B1
EP1496099B1 EP04291494.5A EP04291494A EP1496099B1 EP 1496099 B1 EP1496099 B1 EP 1496099B1 EP 04291494 A EP04291494 A EP 04291494A EP 1496099 B1 EP1496099 B1 EP 1496099B1
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EP
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Prior art keywords
unit
isomerization
paraffins
distillation column
stream
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German (de)
French (fr)
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EP1496099A1 (en
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Laurent Bournay
Dominique Casanave
Elsa Jolimaître
Jean-Francois Joly
Paul Broutin
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IFP Energies Nouvelles IFPEN
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IFP Energies Nouvelles IFPEN
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    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G45/00—Refining of hydrocarbon oils using hydrogen or hydrogen-generating compounds
    • C10G45/58—Refining of hydrocarbon oils using hydrogen or hydrogen-generating compounds to change the structural skeleton of some of the hydrocarbon content without cracking the other hydrocarbons present, e.g. lowering pour point; Selective hydrocracking of normal paraffins
    • C10G45/60—Refining of hydrocarbon oils using hydrogen or hydrogen-generating compounds to change the structural skeleton of some of the hydrocarbon content without cracking the other hydrocarbons present, e.g. lowering pour point; Selective hydrocracking of normal paraffins characterised by the catalyst used
    • C10G45/62—Refining of hydrocarbon oils using hydrogen or hydrogen-generating compounds to change the structural skeleton of some of the hydrocarbon content without cracking the other hydrocarbons present, e.g. lowering pour point; Selective hydrocracking of normal paraffins characterised by the catalyst used containing platinum group metals or compounds thereof
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G35/00—Reforming naphtha
    • C10G35/04—Catalytic reforming
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G2400/00—Products obtained by processes covered by groups C10G9/00 - C10G69/14
    • C10G2400/02—Gasoline

Definitions

  • the product of the isomerization (or isomerate) is free of aromatic compounds in contrast to the reformate which usually contains a significant amount due to dehydrocyclization reactions.
  • Isomerate and reformate are usually sent to the gasoline pool in which other bases such as gasoline resulting from fluidized catalytic cracking (FCC) or additives such as methyl tertiary butyl ether (MTBE) can also be used.
  • FCC fluidized catalytic cracking
  • MTBE methyl tertiary butyl ether
  • Aromatics have high octane numbers that are suitable for use in spark-ignition engines, but for environmental reasons, increasingly stringent specifications result in reduced total aromatics content in gasolines.
  • the process described in the French patent application FR-A-2828205 relates to a process for isomerizing a C 5 -C 8 filler, the C 8+ cut of the naphtha being sent to reforming.
  • the charge C 5 -C 8 is preliminarily separated into two fractions, a first fraction rich in C 5 -C 6 and a second fraction rich in C 7 -C 8 , these two fractions being treated separately in separate reaction zones.
  • the present invention relates more particularly to the isomerization of the second C 7 -C 8 rich fraction which in practice will essentially be a C 7 cut.
  • isomers with only one branch or mono-branched have insufficient octane numbers (42 for 2-methylhexane, 52 for 3-methylhexane) to be mixed with the gasoline pool.
  • These compounds should be as much as possible converted into di- and / or tribranched paraffins in the isomerization process.
  • normal-heptane the problem is even stronger: its octane number being zero, it must imperatively be converted to exhaustion in the isomerization process. Up to 1% by weight of nC7 can be tolerated in the isomerate but if possible less than 0.5% wt.
  • the toluene present in the fresh feedstock is totally hydrogenated to methylcyclohexane either in a specific hydrogenation unit or in the paraffin isomerization unit.
  • the methyl-cyclohexane which is also present in the charge in significant amount is very little affected by the isomerization, the isomerization catalysts very little promoting the opening of naphthenic rings in their usual conditions of implementation.
  • the isomerate C 7 obtained can contain up to 30% by weight of methyl-cyclohexane: this compound whose RON is less than 75 significantly reduces the RON of this isomerization C 7 .
  • the patent US5,382,731 describes a sequence of a naphthenic ring opening reactor followed by an isomerization reactor in the presence of hydrogen and chlorine, this set of reactions being applied to a charge of 6 carbon atoms containing 50% by weight of normal hexane 14.5% by weight of methylcyclopentane, 32% by weight of cyclohexane and 3.9% by weight of benzene.
  • Licences US5,463,155 and US 5,770,042 describe a sequence of a naphthenic ring opening reactor followed by an isomerization reactor supplemented by normal separation of paraffins / isoparaffins in the patent US 5,770,042 .
  • the filler used is a naphtha defined as a petroleum fraction having from 4 to 7 carbon atoms, with a concentration of C 7 preferably limited to 20% by weight.
  • the problem which the present invention seeks to solve is that of the production of gasoline bases from a C 7 fraction which have a search octane number (RON) of at least 80, with a content of aromatic compounds limited to 1% wt, which makes it possible to anticipate the new regulation on the specifications of the gasoline pool.
  • RON search octane number
  • the solution proposed in the present invention consists of a combination of known units, namely at least one isomerization unit and at least one opening unit of the naphthenic rings, the combination having the characteristic of producing a depletion of methylcyclohexane, and normal and mono branched C 7 paraffins responsible for lowering the octane number.
  • exhaustion is meant converting said compounds by systematic recycling into an appropriate unit of the combination of units integrated in the process according to the invention, said compounds having been previously isolated in at least one separation unit.
  • the toluene present in the fresh feed is totally hydrogenated, which makes it possible to limit the aromatic content in the isomerate produced.
  • This C 7 fraction is thus composed of C 7 paraffins, approximately equally distributed in mono-branched and normal paraffins, of C 7 naphthenes, the principal representative of which is methylcyclohexane and of C 7 aromatics, of which unique representative is toluene.
  • the objective of the method which is the subject of the present invention is to transform this C 7 cut into a cut containing predominantly, that is to say at least 70% by weight, preferably at least 85% by weight, of paraffins in C 7 multi -branched, that is to say having a degree of connection greater than or equal to two.
  • the invention relates more specifically to the treatment of the 7-carbon cut and makes it possible to convert the said C 7 cut from the naphtha of first distillation into a 7-carbon cut composed of a majority of di and tribranched paraffins. that is to say containing at least 70% by weight, preferably at least 85% by weight of multi-branched paraffins.
  • the process uses at least one isomerization unit, an opening unit of the naphthenic rings and a separation step comprising at least one distillation column, possibly supplemented by a unit allowing the separation to be carried out.
  • normal and mono-paraffins on the one hand and paraffins di- and tribranched on the other hand.
  • These units are combined to recycle methylcyclohexane, toluene and normal and mono-branched paraffins until exhaustion.
  • a unit may comprise one or more reactors.
  • the present invention therefore relates to the treatment of the 7-carbon fraction resulting from the fractionation described above, but given the performance of the naphtha fractionation unit, it will be possible to find in said C 7 cut to 10% lighter compounds having 6 carbon atoms or less, and up to 10% heavier compounds having 8 or more carbon atoms.
  • the subject of the present invention is a process for producing an isomerization of RON at least equal to 80 and containing less than 1% by weight of aromatics from a cut predominantly consisting of hydrocarbons containing 7 carbon atoms, and containing of the paraffins, naphthenes and aromatics, said process comprising at least one isomerisation unit, at least one naphthenic ring opening unit and at least one separation unit, characterized in that said units are combined in such a way that recycle until exhausted methylcyclohexane, toluene and normal and mono-branched paraffins.
  • the initial section consisting mainly of hydrocarbons with 7 carbon atoms, paraffins, naphthenes and aromatics are in any proportion.
  • exhaustion is meant the conversion of methylcyclohexane, toluene and normal and mono-branched paraffins by systematic recycling into an appropriate unit of the combination of units integrated in the process according to the invention, said compounds having been previously isolated in at least a separation unit.
  • At least one of the separation units is a distillation column supplied with a mixture of different streams, at least one of which comes from the fresh feed, and from which a) a head stream is extracted which, after any further separation, gives the isomerate produced, b) a side stream, which feeds alone or in mixture one of the isomerization units, from which the normal and mono-branched paraffins are converted to exhaustion, and c) a bottom stream from which is recycled to exhaustion toluene and methylcyclohexane contained in the fresh load.
  • nC7 Up to 1% by weight of nC7 can be tolerated in the isomerate constituting the head flow but if possible less than 0.5% by weight.
  • a first isomerization unit is fed by the side withdrawal from the distillation column, the isomerization effluent, after stabilization, being returned to the distillation column on a tray above the draw plate lateral, fresh load feeds the distillation column, and the cycle opening unit is fed by the bottom flow of said column, the effluent of the ring opening unit being recycled to the inlet of the isomerization unit , in mixture with the lateral withdrawal stream from said column.
  • an isomerization unit is fed by the lateral withdrawal from the distillation column, the effluent of the isomerization after stabilization being returned to the distillation column on a plateau located above of the side withdrawal tray, the fresh feed feeds the distillation column and the cycle opening unit is fed by the bottom flow of said column, the effluent of the cycle opening unit being recycled to mixing with the fresh charge at the inlet of said column.
  • one of the isomerization units is fed by the lateral withdrawal from the distillation column, the effluent of this first isomerization after stabilization being returned to the column.
  • the fresh feed feeds a second isomerization unit distinct from the first isomerization unit, the effluent of this second isomerization unit being, after stabilization, sent as feed to the distillation column and the cycle opening unit being fed by the bottom stream of the distillation column, the effluent of the ring opening unit being recycled in admixture with the fresh feed to the entry of the second isomerization unit.
  • one of the isomerization units is fed by the lateral withdrawal from the distillation column, the effluent of this first isomerization after stabilization being returned to the column.
  • the fresh feed feeds the ring opening unit
  • the effluent of this ring opening unit feeds a second isomerization unit distinct from the first isomerization
  • the effluent of this second isomerization unit after stabilization, feeds the distillation column, the bottom flow of the distillation column feeding in mixture with the fresh charge the ring opening unit.
  • one of the isomerization units is fed by the lateral withdrawal from the distillation column, the effluent of this first isomerization after stabilization being returned to the distillation column on a plate located above the lateral withdrawal tray, the fresh feed feeds the distillation column, and the bottom flow of the distillation column feeds the opening unit of cycles, the effluent of this unit
  • the opening of the cycles feeds a second isomerization unit distinct from the first isomerization, the effluent of this second isomerization, after stabilization, feeds the distillation column in a mixture with the fresh feedstock.
  • the overhead stream of the distillation column is sent to a separation unit from which the normal and mono-paraffins which are recycled either at the inlet of the column, on the one hand, are extracted on the one hand.
  • the separation unit used may be based on any technique known to those skilled in the art, for example a molecular sieve adsorption unit such as that described in the patent application. US2002 / 0045793 A1 .
  • the adsorbent used in said unit may be any adsorbent known to those skilled in the art to make this separation, for example the adsorbents described in the patent US 6,353,144 , the patent application FR 02/09841 (Non-homogeneous adsorbent consisting of at least one crystal formed of a core and a continuous outer layer having a diffusional selectivity greater than 5) and the patent application US2002 / 0045793 A1 . It is also conceivable to use one or more membrane modules for this separation, as described for example in the patent application. EP-A1-0192274 .
  • the distillation column may optionally be of the type column-inner wall (divided-wall column in English terminology), which is a technology that applies well in case one has a side racking.
  • one of the separation units involved is supplied with a mixture of different streams, at least one of which comes from the fresh feedstock, and this separation unit is extracted from a feedstock.
  • the normal and mono-paraffins which are recycled at the inlet of an isomerisation unit, and secondly a stream rich in di- and tribranched paraffins and naphthenic which feeds a distillation column which is extracted a) a flow of head which is the isomerate produced, and b) a bottom stream from which the toluene and methylcyclohexane contained in the fresh feed are exhaustively recycled.
  • nC7 can be tolerated in the isomerate constituting the head flow but if possible less than 0.5% by weight.
  • the fresh feed feeds an isomerization unit, the isomerization effluent, after stabilization, feeds the separation unit from which on the one hand the normal and mono are extracted.
  • paraffins which are recycled to the input of the isomerization unit, mixed with the fresh feed, and secondly a rich flow of di- and tribranched paraffins and naphthenic rings which feeds the distillation column, the top flow of which constitutes the isomerate, and whose naphthenic rich bottom stream is fed to the ring opening unit, the effluent of which is recycled to the inlet of the isomerization unit in admixture with the fresh feed and the feedstock. recycle from the separation unit.
  • the fresh feed feeds after stabilization, the separation unit from which are extracted on the one hand the normal and mono-paraffins which are recycled to the input of an isomerization unit and on the other hand, a stream rich in di- and tribranched paraffins and in naphthenic rings which feeds the distillation column, the top flow of which constitutes the isomerate, and whose rich naphthenic bottom flow is fed into the feed.
  • a ring opening unit the effluent of which is recycled mixed with the fresh feedstock and the effluent of the isomerization unit at the inlet of the stabilization.
  • the fresh feed feeds a unit for opening cycles
  • the effluent of said unit feeds an isomerization unit
  • the effluent of the isomerization unit after stabilization feeds the separation unit from which are extracted on the one hand the normal and mono-paraffins which are recycled to the input of the isomerization unit mixed with the effluent of the ring-opening unit, and on the other hand, a stream rich in di- and tribranched paraffins and in naphthenic rings which feeds the distillation column, the top flow of which constitutes the isomerate, and whose rich naphthenic bottom stream is recycled in charge of the daphthenic unit. opening cycles in mixture with the fresh load.
  • one of the separation units involved is a distillation column fed by a mixture of different streams, at least one of which is derived from the fresh feed, from which a flow is extracted.
  • head which feeds a second separation unit which is extracted on the one hand normal and mono-paraffins which are recycled to the input of one of the isomerization units, and secondly a rich flow of di and tribranched paraffins which is the isomerate produced, and b) a bottom stream from which the toluene and methylcyclohexane contained in the fresh feed are exhaustively recycled.
  • the fresh feed feeds an isomerization unit, the isomerization effluent, after stabilization, feeds the distillation column whose feed stream feeds the separation unit of which one extracts on the one hand the normal and mono-paraffins which are recycled at the input of the isomerization unit, mixed with the fresh feedstock, and on the other hand a stream rich in di- and tribranched paraffins which constitutes the isomerate, the bottom stream of the naphthenic rich distillation column is fed to a ring opening unit whose effluent is recycled to the inlet of the isomerization unit in admixture with the fresh feedstock and the recycle from the separation unit.
  • the fresh feed feeds a unit of opening of cycles
  • the effluent of said unit feeds an isomerization unit
  • the effluent of this isomerization unit after stabilization , feeds the distillation column whose head flow feeds the separation unit from which one extracts on the one hand the normal and mono-paraffins which are recycled to the input of the isomerisation unit, in mixing with the effluent of the ring opening unit and secondly a rich flow of di- and tribranched paraffins which constitutes the isomerate, the bottom flow of the column is recycled in charge of the unit of opening of cycles mixed with fresh feed.
  • the fresh feed feeds a unit for opening cycles, the effluent of said unit, after stabilization, feeds the distillation column, the feed of which feeds the feed unit. separation from which are extracted on the one hand the normal and mono-paraffins which are sent as input to a first isomerization unit whose effluent is recycled to the stabilization inlet mixed with the effluent of the opening unit of cycles and on the other hand a flow rich in di- and tribranched paraffins which constitutes the isomerate, the bottom flow of the column feeds a second isomerization unit, whose effluent is recycled in charge of the unit of opening of cycles mixed with fresh feed.
  • the term "rich" stream is understood to mean a stream whose weight composition is such that said compound represents at least 50% by weight, preferably at least 65% by weight and even more preferably at least 80% by weight of the total composition.
  • the hydrogenation of toluene can be carried out in a specific hydrogenation unit. This unit can be placed to process the entire fresh feed, or to process only the feed of the ring opening unit or one of the isomerization units.
  • the charge to be treated (1) is introduced into a distillation column (A) comprising 88 actual trays at the plateau 50.
  • the fresh batch (1) has in the example considered the following composition (in% by weight) and a mass flow rate given below:% by weight dimethyl 2-3 butane 0.01 2-methyl pentane 0.10 methyl-3 pentane 0.14 n-hexane 1.41 methyl-cyclopentane 0.79 cyclohexane 1.64 benzene 0.18 trimethyl 2-2-3 butane 0.06 dimethyl 2-2 pentane 0.15 dimethyl 2-3 pentane 3.66 dimethyl 2-4 pentane 0.42 dimethyl 3-3 pentane 0.24 2-methyl hexane 9.39 3-methyl hexane 12.68 ethyl-3 pentane 1.16 n-heptane 31,20 1,1-dimethylcyclopentane 0.89 cis-dimethyl-1,3 cyclopentane 2.40 1,
  • a flow (2) which corresponds to the product isomerate and whose weight composition and mass flow rate are as follows: isopentane 4.23 dimethyl 2-2 butane 0.22 dimethyl 2-3 butane 0.18 2-methyl pentane 0.83 methyl-3 pentane 0.53 n-hexane 2.21 methyl-cyclopentane 0.97 cyclohexane 1.93 benzene 0.18 trimethyl 2-2-3 butane 8.12 dimethyl 2-2 pentane 22.04 dimethyl 2-3 pentane 0.88 dimethyl 2-4 pentane 47,23 dimethyl 3-3 pentane 3.07 2-methyl hexane 4.34 3-methyl hexane 1.79 ethyl-3 pentane 0.06 n-heptane 0.50 1,1-dimethylcyclopentane 0.20 cis-dimethyl-1,3 cyclopentane 0.08 1,3-trans-1,3-dimethylcyclopentane 0.07 1,2-trans-1,
  • the RON of this isomerate (stream 2) is 84.2 and its aromatic content is 0.18 wt%.
  • stream (3) containing a majority (at least 70%) of normal-heptane and C 7 paraffins mono-branched.
  • a stream (4) which is a rich flow of methylcyclohexane, toluene and n-heptane.
  • This stream (4) is sent to a toluene-specific hydrogenation unit (B) and then to a ring-opening unit (C) which produces an effluent (5) containing mainly a mixture of paraffins resulting in part from the opening of the rings, as well as unconverted methyl-cyclohexane, toluene being completely hydrogenated.
  • the catalyst used for the ring opening unit may be any catalyst for ring-opening conversion of at least 5% of the methylcyclohexane present in the mixture to be treated.
  • the ring opening unit uses an iridium catalyst deposited on alumina or silica-alumina, such as that described in the patent application. WO 02/07881 .
  • the weight composition and the mass flow rate (excluding hydrogen) of the stream (5) corresponding to the effluent of the ring opening unit are as follows: C 5- 1.82 paraffins C 5 3.69 paraffins C 6 1.72 methyl-cyclopentane 0.00 cyclohexane 0.00 benzene 0.00 paraffins C 7 71.13 1,1-dimethylcyclopentane 0.39 cis-dimethyl-1,3 cyclopentane 0.37 1,3-trans-1,3-dimethylcyclopentane 0.40 1,2-trans-1,2-dimethylcyclopentane 0.40 methyl-cyclohexane 19.18 ethyl-cyclopentane 0.39 toluene 0.00 C 8+ 0.51 total flow (kg / h) 10962
  • the stream (5) is mixed with the stream (3) to give a stream (6) which is introduced into an isomerization unit (D) using a platinum catalyst on chlorinated alumina as described in the application patent US2002 / 0002319 A1 .
  • the weight composition and the mass flow rate (excluding hydrogen) of the stream (7) corresponding to the effluent of the isomerization unit are as follows: C 5- 2.54 isopentane 0.56 dimethyl 2-2 butane 0.03 dimethyl 2-3 butane 0.02 2-methyl pentane 0.10 methyl-3 pentane 0.05 n-hexane 0.12 methyl-cyclopentane 0.04 cyclohexane 0.10 benzene 0.00 trimethyl 2-2-3 butane 1.63 dimethyl 2-2 pentane 3.26 dimethyl 2-3 pentane 4.08 dimethyl 2-4 pentane 8.16 dimethyl 3-3 pentane 4.08 2-methyl hexane 22.04 3-methyl hexane 16.32 ethyl-3 pentane 0.82 n-heptane 21,22 1,1-dimethylcyclopentane 0.33 cis-dimethyl-1,3 cyclopentane 0.32 1,3-trans-1,3-dimethylcyclopentane 0.34 1,
  • the effluent (7) of the isomerization unit is sent to a stabilization column (E) from which a flow (9) comprising the light gases resulting from the cracking reactions within the isomerization unit (C 5- cut) and bottom a flow (8) whose composition is very close to that of the flow (7) and which is reintroduced at the top of the column (A) at the plateau 12 .
  • the mass flow (excluding hydrogen) of the flow (9) amounts to 1800 kg / h.

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Description

Domaine de l'invention : Field of the invention

La suppression des alkyles de plomb dans les essences automobiles, et plus récemment la limitation des teneurs en composés aromatiques dans les essences (35% en 2005 contre 42 % actuellement) a généré un développement des procédés de production de paraffines ramifiées qui ont un bien meilleur indice d'octane que les paraffines linéaires, et en particulier un développement des procédés d'isomérisation des paraffines normales en paraffines ramifiées. Ces procédés revêtent actuellement une importance croissante dans l'industrie pétrolière.The suppression of lead alkyls in automotive gasolines, and more recently the limitation of aromatics content in gasolines (35% in 2005 against 42% currently) has led to a development of branched paraffin production processes which have a much better octane number than linear paraffins, and in particular a development of isomerization processes from normal paraffins to branched paraffins. These processes are becoming increasingly important in the oil industry.

Les schémas actuels de valorisation du naphta (coupe C5-C10) issu de la distillation atmosphérique du pétrole comprennent le plus souvent un fractionnement produisant :

  • un naphta léger (coupe C5-C6) qui est envoyé à l'isomérisation,
  • un naphta lourd (coupe C7-C10) qui est envoyé au reformage catalytique.
The current valorization schemes for naphtha (C 5 -C 10 cut) resulting from the atmospheric distillation of petroleum most often include a fractionation producing:
  • a light naphtha (C 5 -C 6 cut) which is sent to isomerization,
  • a heavy naphtha (C 7 -C 10 cut) which is sent to catalytic reforming.

Le produit de l'isomérisation (ou isomérat) est exempt de composés aromatiques contrairement au réformat qui en contient en général une quantité importante du fait des réactions de déshydrocyclisation.The product of the isomerization (or isomerate) is free of aromatic compounds in contrast to the reformate which usually contains a significant amount due to dehydrocyclization reactions.

Isomérat et réformat sont habituellement envoyés au pool essence dans lequel peuvent intervenir également d'autres bases telles que l'essence issue du craquage catalytique en lit fluidisé (FCC), ou des additifs tel que le méthyl-tertiobutyl-éther (MTBE).Isomerate and reformate are usually sent to the gasoline pool in which other bases such as gasoline resulting from fluidized catalytic cracking (FCC) or additives such as methyl tertiary butyl ether (MTBE) can also be used.

Les aromatiques présentent de hauts indices d'octane propices à leur utilisation dans les moteurs à allumage commandé, mais pour des raisons environnementales, les spécifications de plus en plus sévères conduisent à réduire la teneur totale en aromatiques dans les essences.Aromatics have high octane numbers that are suitable for use in spark-ignition engines, but for environmental reasons, increasingly stringent specifications result in reduced total aromatics content in gasolines.

La spécification européenne prévoit dès 2005 de réduire à un maximum de 35 % en volume la teneur totale en aromatiques dans les supercarburants, alors qu'actuellement ladite teneur est de l'ordre de 42 % volume.As of 2005, the European specification plans to reduce the total content of aromatics in super-fuels to a maximum of 35% by volume, whereas currently the content is of the order of 42% by volume.

Ainsi, il est impératif de développer de nouveaux procédés permettant de synthétiser de nouvelles bases exemptes d'aromatiques mais présentant de forts indices d'octane.Thus, it is imperative to develop new processes for synthesizing new bases that are free of aromatics but have high octane numbers.

Parmi ceux-ci, le procédé décrit dans la demande de brevet française FR-A-2,828,205 concerne un procédé d'isomérisation d'une charge C5-C8, la coupe C8+ du naphta étant envoyée au reforming. La charge C5-C8 est préalablement séparée en deux fractions, une première fraction riche en C5-C6 et une seconde fraction riche en C7-C8, ces deux fractions étant traitées séparément dans des zones réactionnelles distinctes.Among these, the process described in the French patent application FR-A-2828205 relates to a process for isomerizing a C 5 -C 8 filler, the C 8+ cut of the naphtha being sent to reforming. The charge C 5 -C 8 is preliminarily separated into two fractions, a first fraction rich in C 5 -C 6 and a second fraction rich in C 7 -C 8 , these two fractions being treated separately in separate reaction zones.

La présente invention concerne plus particulièrement l'isomérisation de la seconde fraction riche en C7-C8 qui dans la pratique sera essentiellement une coupe C7.The present invention relates more particularly to the isomerization of the second C 7 -C 8 rich fraction which in practice will essentially be a C 7 cut.

Le tableau ci-dessous donne l'indice d'octane recherche (RON) des principaux composés hydrocarbonés en C7 qui sont présents dans cette seconde fraction ainsi que leur température normale d'ébullition. RON teb (°C) triméthyl 2-2-3 butane 112,1 80,8 diméthyl 2-2 pentane 92,8 79,2 diméthyl 2-4 pentane 83,1 80,5 diméthyl 3-3 pentane 80,8 86 diméthyl 2-3 pentane 91,1 89,7 méthyl-2 hexane 42,4 90 méthyl-3 hexane 52 91,9 éthyl-3 pentane 65 93,4 n-heptane 0 98,4 diméthyl-1,1 cyclopentane 92,3 87,8 cis-diméthyl-1,3 cyclopentane 79,2 90,8 trans-diméthyl-1,3 cyclopentane 80,6 91,7 trans-diméthyl-1,2 cyclopentane 80,6 91,8 méthyl-cyclohexane 74,8 100,9 éthyl-cyclopentane 67,2 103,4 toluène 120 110,7 The table below gives the research octane number (RON) of the main C 7 hydrocarbon compounds present in this second fraction as well as their normal boiling point. RON teb (° C) trimethyl 2-2-3 butane 112.1 80.8 dimethyl 2-2 pentane 92.8 79.2 dimethyl 2-4 pentane 83.1 80.5 dimethyl 3-3 pentane 80.8 86 dimethyl 2-3 pentane 91.1 89.7 2-methyl hexane 42.4 90 3-methyl hexane 52 91.9 ethyl-3 pentane 65 93.4 n-heptane 0 98.4 1,1-dimethylcyclopentane 92.3 87.8 cis-dimethyl-1,3 cyclopentane 79.2 90.8 1,3-trans-1,3-dimethylcyclopentane 80.6 91.7 1,2-trans-1,2-dimethylcyclopentane 80.6 91.8 methyl-cyclohexane 74.8 100.9 ethyl-cyclopentane 67.2 103.4 toluene 120 110.7

La considération des indices d'octane des différents isomères C7 montre que les isomères du normal-heptane (n-C7) présentant plusieurs ramifications, c'est-à-dire les di- et tribranchés possèdent un indice d'octane suffisamment élevé (de 80 à 110) pour pouvoir être envoyés directement dans le pool essence.The consideration of the octane numbers of the different C 7 isomers shows that the isomers of normal-heptane (nC 7 ) with several branches, ie the di- and tribranchs have a sufficiently high octane number (from 80 to 110) to be sent directly to the gasoline pool.

Par contre, les isomères ne présentant qu'une seule ramification ou monobranchés, présentent des indices d'octane insuffisants (42 pour le méthyl-2 hexane ; 52 pour le méthyl-3 hexane) pour être mélangés au pool essence. Ces composés doivent être le plus possible transformés en paraffines di- et /ou tribranchées dans le procédé d'isomérisation. Concernant le normal-heptane, la problématique est plus forte encore : son indice d'octane étant nul, il doit impérativement être converti à épuisement dans le procédé d'isomérisation. On pourra tolérer jusqu'à 1 % pds de nC7 dans l'isomérat mais si possible moins de 0,5 % pds.On the other hand, isomers with only one branch or mono-branched, have insufficient octane numbers (42 for 2-methylhexane, 52 for 3-methylhexane) to be mixed with the gasoline pool. These compounds should be as much as possible converted into di- and / or tribranched paraffins in the isomerization process. Regarding normal-heptane, the problem is even stronger: its octane number being zero, it must imperatively be converted to exhaustion in the isomerization process. Up to 1% by weight of nC7 can be tolerated in the isomerate but if possible less than 0.5% wt.

Par ailleurs, le toluène présent dans la charge fraîche est totalement hydrogéné en méthyl-cyclohexane soit dans une unité d'hydrogénation spécifique, soit dans l'unité d'isomérisation des paraffines. Or, le méthyl-cyclohexane qui est également présent dans la charge en quantité importante est très peu affecté par l'isomérisation, les catalyseurs d'isomérisation favorisant très peu l'ouverture des cycles naphténiques dans leurs conditions habituelles de mise en oeuvre. L'isomérat C7 obtenu peut contenir jusqu'à 30 % pds de méthyl-cyclohexane : ce composé dont le RON est inférieur à 75 diminue notablement le RON de cet isomérat C7. Afin de maximiser le RON de l'isomérat produit, il paraît donc intéressant de convertir le méthyl-cyclohexane en paraffines dans une unité d'ouverture de cycles, afin de réduire la teneur en méthyl-cyclohexane de l'isomérat C7. Ainsi la demande de brevet WO 02/07881 porte sur un catalyseur à base d'iridium sur silice-alumine permettant de réaliser la réaction d'ouverture des cycles naphténiques. Le brevet US 5,382,731 décrit un enchaînement d'un réacteur à ouverture de cycles naphténiques suivi d'un réacteur d'isomérisation en présence d'hydrogène et de chlore, cet ensemble de réactions étant appliqué à une charge à 6 atomes de carbone comportant 50 % poids de normal hexane, 14,5 % poids de méthyl-cyclopentane, 32% poids de cyclohexane et 3,9 %poids de benzène. Les brevets US 5,463,155 et US 5,770,042 décrivent un enchaînement d'un réacteur à ouverture de cycles naphténiques suivi d'un réacteur d'isomérisation complété par une séparation normale paraffines / isoparaffines dans le brevet US 5,770,042 . La charge utilisée est un naphta défini comme une coupe pétrolière ayant de 4 à 7 atomes de carbone, avec une concentration en C7 préférentiellement limitée à 20 % poids. Enfin, le brevet US 2,915,571 décrit un enchaînement d'une isomérisation suivie d'une colonne de distillation et d'un réacteur d'ouverture de cycles.Moreover, the toluene present in the fresh feedstock is totally hydrogenated to methylcyclohexane either in a specific hydrogenation unit or in the paraffin isomerization unit. However, the methyl-cyclohexane which is also present in the charge in significant amount is very little affected by the isomerization, the isomerization catalysts very little promoting the opening of naphthenic rings in their usual conditions of implementation. The isomerate C 7 obtained can contain up to 30% by weight of methyl-cyclohexane: this compound whose RON is less than 75 significantly reduces the RON of this isomerization C 7 . In order to maximize the RON of the isomerate produced, it therefore seems advantageous to convert the methyl-cyclohexane to paraffins in a ring-opening unit in order to reduce the methyl-cyclohexane content of the C7 isomerate. Thus the patent application WO 02/07881 relates to an iridium catalyst on silica-alumina for performing the opening reaction of naphthenic rings. The patent US5,382,731 describes a sequence of a naphthenic ring opening reactor followed by an isomerization reactor in the presence of hydrogen and chlorine, this set of reactions being applied to a charge of 6 carbon atoms containing 50% by weight of normal hexane 14.5% by weight of methylcyclopentane, 32% by weight of cyclohexane and 3.9% by weight of benzene. Licences US5,463,155 and US 5,770,042 describe a sequence of a naphthenic ring opening reactor followed by an isomerization reactor supplemented by normal separation of paraffins / isoparaffins in the patent US 5,770,042 . The filler used is a naphtha defined as a petroleum fraction having from 4 to 7 carbon atoms, with a concentration of C 7 preferably limited to 20% by weight. Finally, the patent US 2,915,571 describes a sequence of isomerization followed by a distillation column and a ring opening reactor.

Le problème que cherche à résoudre la présente invention est celui de la production de bases d'essence à partir d'une coupe en C7 qui répondent à un indice d'octane recherche (RON) d'au moins 80, avec une teneur en composés aromatiques limitée à 1% pds, ce qui permet d'anticiper la nouvelle réglementation sur les spécifications du pool essence.The problem which the present invention seeks to solve is that of the production of gasoline bases from a C 7 fraction which have a search octane number (RON) of at least 80, with a content of aromatic compounds limited to 1% wt, which makes it possible to anticipate the new regulation on the specifications of the gasoline pool.

La solution proposée dans la présente invention consiste en une combinaison d'unités connues nommément, au moins une unité d'isomérisation et au moins une unité d'ouverture des cycles naphténiques, la combinaison ayant comme caractéristique de réaliser un épuisement du méthyl-cyclohexane, et des paraffines en C7 normales et mono branchées responsables de l'abaissement de l'indice d'octane. On entend par épuisement le fait de convertir lesdits composés par recyclage systématique dans une unité appropriée de la combinaison d'unités intégrées au procédé selon l'invention, les dits composés ayant été préalablement isolés dans au moins une unité de séparation.The solution proposed in the present invention consists of a combination of known units, namely at least one isomerization unit and at least one opening unit of the naphthenic rings, the combination having the characteristic of producing a depletion of methylcyclohexane, and normal and mono branched C 7 paraffins responsible for lowering the octane number. By exhaustion is meant converting said compounds by systematic recycling into an appropriate unit of the combination of units integrated in the process according to the invention, said compounds having been previously isolated in at least one separation unit.

Les nombreuses variantes qui seront décrites dans la suite du texte ont toutes en commun cette notion d'épuisement.The many variants that will be described in the rest of the text all have in common this notion of exhaustion.

Par ailleurs, le toluène présent dans la charge fraîche est totalement hydrogéné ce qui permet de limiter la teneur en aromatiques dans l'isomérat produit.In addition, the toluene present in the fresh feed is totally hydrogenated, which makes it possible to limit the aromatic content in the isomerate produced.

L'art antérieur décrit ci-dessus fait apparaître individuellement les unités qui sont utilisées dans la présente invention, mais il ne les combine pas de la manière décrite par la Demanderesse, c'est-à-dire avec des recyclages à épuisement des paraffines normales et monobranchées, en particulier des paraffines normales et monobranchées en C7 non converties d'une part, et des naphtènes, en particulier du méthyl-cyclohexane, et des aromatiques, en particulier du toluène, d'autre part.The prior art described above individually shows the units that are used in the present invention, but it does not combine them in the manner described by the Applicant, that is to say with normal paraffin depletion recycling. and monobranched, in particular unconverted C 7 normal and mono-branched paraffins, and naphthenes, in particular methylcyclohexane, and aromatics, in particular toluene, on the other hand.

Présentation sommaire de l'invention : Brief presentation of the invention :

La présente invention concerne un procédé de production de paraffines multi-branchées à 7 atomes de carbone, permettant d'obtenir un isomérat ayant un indice d'octane au moins égal à 80 avec une teneur en composés aromatiques inférieure à 1%, à partir d'une charge comprenant en majeure partie des hydrocarbures à 7 atomes de carbone appartenant aux familles des paraffines, des naphtènes et des aromatiques selon les revendications 1 à 6. Dans la suite de la description, on utilisera l'abréviation coupe C7 pour désigner une charge comprenant une majeure partie d'hydrocarbures à 7 atomes de carbone, cette coupe C7 étant généralement issue d'un naphta de première distillation, et ayant une composition chimique qui varie avec l'origine de la coupe naphta dans les fourchettes typiques données ci dessous :

  • normal-heptane de 20 à 35 % poids,
  • méthyl-2 hexane de 5 à 10 % poids,
  • méthyl-3 hexane de 10 à 15% poids,
  • méthyl-cyclohexane de 10 à 25 % poids,
  • toluène de 4 à 15 % poids.
The present invention relates to a process for the production of 7-carbon multi-branched paraffins, which makes it possible to obtain an isomerate having an octane number of at least 80 with an aromatic content of less than 1%, starting from a feedstock comprising, for the most part, 7-carbon hydrocarbons belonging to the families of paraffins, naphthenes and aromatics according to claims 1 to 6. In the rest of the description, the abbreviation C 7 cut will be used to denote a filler comprising a major portion of hydrocarbons having 7 carbon atoms, this C 7 cut being generally derived from a naphtha of first distillation, and having a chemical composition which varies with the origin of the naphtha cut in the typical ranges given herein below:
  • normal-heptane from 20 to 35% by weight,
  • 2-methylhexane of 5 to 10% by weight,
  • 3-methylhexane of 10 to 15% by weight,
  • methylcyclohexane of 10 to 25% by weight,
  • toluene from 4 to 15% by weight.

Cette coupe en C7 est donc composée de paraffines en C7, à peu près également réparties en paraffines monobranchées et normales, de naphtènes en C7 dont le représentant principal est le méthyl-cyclohexane et d'aromatiques en C7, dont l'unique représentant est le toluène.This C 7 fraction is thus composed of C 7 paraffins, approximately equally distributed in mono-branched and normal paraffins, of C 7 naphthenes, the principal representative of which is methylcyclohexane and of C 7 aromatics, of which unique representative is toluene.

L'objectif du procédé objet de la présente invention est de transformer cette coupe C7 en une coupe contenant majoritairement, c'est-à-dire au moins 70% poids, de préférence au moins 85% poids, des paraffines en C7 multi-branchées, c'est-à-dire présentant un degré de branchement supérieur ou égal à deux.The objective of the method which is the subject of the present invention is to transform this C 7 cut into a cut containing predominantly, that is to say at least 70% by weight, preferably at least 85% by weight, of paraffins in C 7 multi -branched, that is to say having a degree of connection greater than or equal to two.

Ces paraffines multi-branchées vont conférer à la coupe correspondante un indice d'octane recherche (RON) élevé, c'est-à-dire d'au moins 80, et qui peut atteindre et même dépasser 87. Ce nombre d'octane peut en pratique être légèrement inférieur en raison de la présence résiduelle d'environ 10 % ou moins de paraffines normales et monobranchées.These multi-branched paraffins will give the corresponding cut a high research octane number (RON), that is to say at least 80, and which can reach and even exceed 87. This octane number can in practice, it is slightly lower due to the residual presence of about 10% or less of normal and mono-branched paraffins.

La transformation de la coupe C7 de départ en la coupe C7 finale, composée d'une majorité de paraffines dibranchées nécessite plusieurs types de réaction :

  1. 1) la transformation des normales paraffines en paraffines branchées et des paraffines mono branchées en multibranchées qui est réalisée par une unité d'isomérisation travaillant sous pression partielle d'hydrogène, et qu'on appelle pour cette raison unité d'hydroisomérisation.
  2. 2) la transformation des naphtènes, essentiellement le méthyl-cyclohexane en paraffines multibranchées qui nécessite une première étape d'ouverture du cycle naphténique pour transformer le méthyl-cyclohexane en paraffines, puis la transformation ultérieure de ces paraffines en paraffines multibranchées dans l'unité d'isomérisation. L'unité d'ouverture des cycles naphténiques est également opérée sous pression partielle d'hydrogène.
  3. 3) la transformation du toluène en méthyl-cyclohexane qui a lieu soit dans une unité spécifique d'hydrogénation, soit dans l'unité d'isomérisation, soit dans l'unité d'ouverture de cycles.
The transformation of the cut C 7 starting in the C final cut 7, composed of a majority of di-branched paraffins requires several types of reaction:
  1. 1) the conversion of normal paraffins into branched paraffins and branched mono-branched paraffins which is carried out by an isomerization unit working under partial pressure of hydrogen, and which is therefore called hydroisomerization unit.
  2. 2) the conversion of naphthenes, essentially methyl-cyclohexane to multi-branched paraffins which requires a first step of opening the naphthenic ring to convert methyl-cyclohexane to paraffins, and then the subsequent conversion of these paraffins into multi-branched paraffins in the naphthenic unit. isomerization. The opening unit of the naphthenic rings is also operated under hydrogen partial pressure.
  3. 3) the conversion of toluene to methylcyclohexane which takes place either in a specific hydrogenation unit, in the isomerization unit, or in the ring-opening unit.

L'invention porte plus précisément sur le traitement de la coupe à 7 atomes de carbone et permet de transformer la dite coupe C7 issue du naphta de première distillation en une coupe à 7 atomes de carbone composée d'une majorité de paraffines di et tribranchées, c'est-à-dire contenant au moins 70% poids, de préférence au moins 85% poids de paraffines multibranchées.The invention relates more specifically to the treatment of the 7-carbon cut and makes it possible to convert the said C 7 cut from the naphtha of first distillation into a 7-carbon cut composed of a majority of di and tribranched paraffins. that is to say containing at least 70% by weight, preferably at least 85% by weight of multi-branched paraffins.

Pour réaliser ces transformations, le procédé fait appel à au moins une unité d'isomérisation, une unité d'ouverture des cycles naphténiques et une étape de séparation comportant au moins une colonne à distiller, éventuellement complétée par une unité permettant d'effectuer la séparation des normales et mono- paraffines d'une part, et des paraffines di- et tribranchées d'autre part. Ces unités sont combinées de manière à recycler jusqu'à épuisement le méthylcyclohexane, le toluène et les paraffines normales et monobranchées. De manière générale, une unité pourra comporter un ou plusieurs réacteurs.To carry out these transformations, the process uses at least one isomerization unit, an opening unit of the naphthenic rings and a separation step comprising at least one distillation column, possibly supplemented by a unit allowing the separation to be carried out. normal and mono-paraffins on the one hand, and paraffins di- and tribranched on the other hand. These units are combined to recycle methylcyclohexane, toluene and normal and mono-branched paraffins until exhaustion. In general, a unit may comprise one or more reactors.

Les schémas qui sont décrits dans la présente invention permettent de répondre à la demande d'octane dans le respect des teneurs admissibles en aromatiques dans l'essence, en maximisant la formation de composés paraffiniques multibranchés après avoir séparé la coupe naphta d'origine en 3 fractions:

  1. 1) une fraction de tête comportant essentiellement les composés à 5 et 6 atomes de carbone qui est envoyée dans une isomérisation spécifique dont les conditions opératoires et le catalyseur peuvent être différents de ceux utilisés pour l'isomérisation de la coupe C7.
  2. 2) une fraction à 7 atomes de carbone qui fait l'objet du traitement décrit dans la présente invention et qui aboutit à un effluent à 7 atomes de carbone contenant au moins 70 % poids, de préférence au moins 85% poids, de paraffines di et tribranchées et dont le nombre d'octane est d'au moins 80, de préférence compris entre 80 et 87. Cette fraction à 7 atomes de carbone pourra éventuellement avant le traitement décrit dans la présente invention subir un prétraitement permettant de réduire jusqu'à des valeurs inférieures à 0,5 % poids la teneur en toluène au travers d'une unité spécifique d'hydrogénation.
  3. 3) une fraction de fond contenant essentiellement les composés à 8 atomes de carbone et plus qui est envoyée dans une unité de reformage catalytique.
The schemes which are described in the present invention make it possible to meet the octane demand while respecting the acceptable aromatics content in gasoline, by maximizing the formation of multi-branched paraffinic compounds after having separated the original naphtha cut into 3 fractions:
  1. 1) a head fraction comprising essentially the compounds with 5 and 6 carbon atoms which is sent in a specific isomerization whose operating conditions and the catalyst may be different from those used for the isomerization of the C 7 cut.
  2. 2) a fraction containing 7 carbon atoms which is the subject of the treatment described in the present invention and which results in an effluent with 7 carbon atoms containing at least 70% by weight, preferably at least 85% by weight, of paraffins di and tribranched and whose octane number is at least 80, preferably between 80 and 87. This fraction with 7 carbon atoms may possibly before the treatment described in the present invention undergo a pretreatment to reduce up to values lower than 0.5% by weight toluene content through a specific unit of hydrogenation.
  3. 3) a bottom fraction essentially containing the compounds with 8 or more carbon atoms which is sent to a catalytic reforming unit.

La présente invention porte donc sur le traitement de la fraction à 7 atomes de carbone issue du fractionnement décrit ci-dessus, mais étant donné les performances de l'unité de fractionnement du naphta, on pourra trouver dans la dite coupe C7 jusqu'à 10 % de composés plus légers ayant 6 atomes de carbone ou moins, et jusqu'à 10 % de composés plus lourds ayant 8 atomes de carbone et plus.The present invention therefore relates to the treatment of the 7-carbon fraction resulting from the fractionation described above, but given the performance of the naphtha fractionation unit, it will be possible to find in said C 7 cut to 10% lighter compounds having 6 carbon atoms or less, and up to 10% heavier compounds having 8 or more carbon atoms.

Description de l'invention : Description of the invention

La présente invention a pour objet un procédé de production d'un isomérat de RON au moins égal à 80 et contenant moins de 1% poids d'aromatiques à partir d'une coupe majoritairement constituée d'hydrocarbures à 7 atomes de carbone, et contenant des paraffines, des naphtènes et des aromatiques, le dit procédé comprenant au moins une unité d'isomérisation, au moins une unité d'ouverture des cycles naphténiques et au moins une unité de séparation, caractérisé en ce que les dites unités sont combinées de manière à recycler jusqu'à épuisement le methylcyclohexane, le toluène et les paraffines normales et monobranchées. Dans la coupe initiale majoritairement constituée d'hydrocarbures à 7 atomes de carbone, les paraffines, les naphtènes et les aromatiques sont en proportion quelconque.The subject of the present invention is a process for producing an isomerization of RON at least equal to 80 and containing less than 1% by weight of aromatics from a cut predominantly consisting of hydrocarbons containing 7 carbon atoms, and containing of the paraffins, naphthenes and aromatics, said process comprising at least one isomerisation unit, at least one naphthenic ring opening unit and at least one separation unit, characterized in that said units are combined in such a way that recycle until exhausted methylcyclohexane, toluene and normal and mono-branched paraffins. In the initial section consisting mainly of hydrocarbons with 7 carbon atoms, paraffins, naphthenes and aromatics are in any proportion.

On entend par épuisement le fait de convertir le methylcyclohexane, le toluène et les paraffines normales et monobranchées par recyclage systématique dans une unité appropriée de la combinaison d'unités intégrées au procédé selon l'invention, les dits composés ayant été préalablement isolés dans au moins une unité de séparation. Au moins une des unités de séparation est une colonne de distillation alimentée par un mélange de différents flux dont l'un au moins est issu de la charge fraîche, et dont on extrait a) un flux de tête qui, après éventuelle séparation supplémentaire, donne l'isomérat produit, b) un flux latéral, qui alimente seul ou en mélange une des unités d'isomérisation, à partir duquel on convertit à épuisement les paraffines normales et monobranchées, et c) un flux de fond à partir duquel on recycle à épuisement le toluène et le methylcyclohexane contenus dans la charge fraîche.By exhaustion is meant the conversion of methylcyclohexane, toluene and normal and mono-branched paraffins by systematic recycling into an appropriate unit of the combination of units integrated in the process according to the invention, said compounds having been previously isolated in at least a separation unit. At least one of the separation units is a distillation column supplied with a mixture of different streams, at least one of which comes from the fresh feed, and from which a) a head stream is extracted which, after any further separation, gives the isomerate produced, b) a side stream, which feeds alone or in mixture one of the isomerization units, from which the normal and mono-branched paraffins are converted to exhaustion, and c) a bottom stream from which is recycled to exhaustion toluene and methylcyclohexane contained in the fresh load.

On pourra tolérer jusqu'à 1 % poids de nC7 dans l'isomérat constituant le flux de tête mais si possible moins de 0,5 % pds. Selon l'invention (Cf figure 1), une première unité d'isomérisation est alimentée par le soutirage latéral issu de la colonne de distillation, l'effluent de l'isomérisation, après stabilisation, étant renvoyé à la colonne de distillation sur un plateau situé au-dessus du plateau de soutirage latéral, la charge fraîche alimente la colonne de distillation, et l'unité d'ouverture de cycles est alimentée par le flux de fond de la dite colonne, l'effluent de l'unité d'ouverture de cycles étant recyclé en entrée de l'unité d'isomérisation, en mélange avec le flux de soutirage latéral issu de la dite colonne.Up to 1% by weight of nC7 can be tolerated in the isomerate constituting the head flow but if possible less than 0.5% by weight. According to the invention (cf. figure 1 ), a first isomerization unit is fed by the side withdrawal from the distillation column, the isomerization effluent, after stabilization, being returned to the distillation column on a tray above the draw plate lateral, fresh load feeds the distillation column, and the cycle opening unit is fed by the bottom flow of said column, the effluent of the ring opening unit being recycled to the inlet of the isomerization unit , in mixture with the lateral withdrawal stream from said column.

Dans une seconde variante de l'invention, une unité d'isomérisation est alimentée par le soutirage latéral issu de la colonne de distillation, l'effluent de l'isomérisation après stabilisation étant renvoyé à la colonne de distillation sur un plateau situé au-dessus du plateau de soutirage latéral, la charge fraîche alimente la colonne de distillation et l'unité d'ouverture de cycles est alimentée par le flux de fond de la dite colonne, l'effluent de l'unité d'ouverture de cycles étant recyclé en mélange avec la charge fraîche en entrée de la dite colonne.In a second variant of the invention, an isomerization unit is fed by the lateral withdrawal from the distillation column, the effluent of the isomerization after stabilization being returned to the distillation column on a plateau located above of the side withdrawal tray, the fresh feed feeds the distillation column and the cycle opening unit is fed by the bottom flow of said column, the effluent of the cycle opening unit being recycled to mixing with the fresh charge at the inlet of said column.

Dans un exemple ne faisant pas partie de l'invention, une des unités d'isomérisation, appelée première isomérisation, est alimentée par le soutirage latéral issu de la colonne de distillation, l'effluent de cette première isomérisation après stabilisation étant renvoyé à la colonne de distillation sur un plateau situé au-dessus du plateau de soutirage latéral, la charge fraîche alimente une seconde unité d'isomérisation distincte de la première unité d'isomérisation, l'effluent de cette seconde unité d'isomérisation étant, après stabilisation, envoyé comme charge de la colonne de distillation et l'unité d'ouverture de cycles étant alimentée par le flux de fond de la colonne de distillation, l'effluent de l'unité d'ouverture de cycles étant recyclé en mélange avec la charge fraîche à l'entrée de la seconde unité d'isomérisation.In an example not forming part of the invention, one of the isomerization units, called the first isomerization, is fed by the lateral withdrawal from the distillation column, the effluent of this first isomerization after stabilization being returned to the column. on a plate above the lateral withdrawal tray, the fresh feed feeds a second isomerization unit distinct from the first isomerization unit, the effluent of this second isomerization unit being, after stabilization, sent as feed to the distillation column and the cycle opening unit being fed by the bottom stream of the distillation column, the effluent of the ring opening unit being recycled in admixture with the fresh feed to the entry of the second isomerization unit.

Dans un exemple ne faisant pas partie de l'invention, une des unités d'isomérisation, appelée première isomérisation, est alimentée par le soutirage latéral issu de la colonne de distillation, l'effluent de cette première isomérisation après stabilisation étant renvoyé à la colonne de distillation sur un plateau situé au-dessus du plateau de soutirage latéral, la charge fraîche alimente l'unité d'ouverture de cycles, l'effluent de cette unité d'ouverture de cycles alimente une seconde unité d'isomérisation distincte de la première isomérisation, et l'effluent de cette seconde unité d'isomérisation, après stabilisation, alimente la colonne de distillation, le flux de fond de la colonne de distillation alimentant en mélange avec la charge fraîche l'unité d'ouverture de cycles.In an example not forming part of the invention, one of the isomerization units, called the first isomerization, is fed by the lateral withdrawal from the distillation column, the effluent of this first isomerization after stabilization being returned to the column. on a plate above the lateral draw plate, the fresh feed feeds the ring opening unit, the effluent of this ring opening unit feeds a second isomerization unit distinct from the first isomerization, and the effluent of this second isomerization unit, after stabilization, feeds the distillation column, the bottom flow of the distillation column feeding in mixture with the fresh charge the ring opening unit.

Dans une troisième variante de l'invention, une des unités d'isomérisation, appelée première isomérisation, est alimentée par le soutirage latéral issu de la colonne de distillation, l'effluent de cette première isomérisation après stabilisation étant renvoyé à la colonne de distillation sur un plateau situé au dessus du plateau de soutirage latéral, la charge fraîche alimente la colonne de distillation, et le flux de fond de la colonne de distillation alimente l'unité d'ouverture de cycles, l'effluent de cette unité d'ouverture de cycles alimente une seconde unité d'isomérisation distincte de la première isomérisation, l'effluent de cette seconde isomérisation, après stabilisation, alimente en mélange avec la charge fraîche la colonne de distillation.In a third variant of the invention, one of the isomerization units, called the first isomerization, is fed by the lateral withdrawal from the distillation column, the effluent of this first isomerization after stabilization being returned to the distillation column on a plate located above the lateral withdrawal tray, the fresh feed feeds the distillation column, and the bottom flow of the distillation column feeds the opening unit of cycles, the effluent of this unit The opening of the cycles feeds a second isomerization unit distinct from the first isomerization, the effluent of this second isomerization, after stabilization, feeds the distillation column in a mixture with the fresh feedstock.

Dans une quatrième variante du procédé selon l'invention le flux de tête de la colonne de distillation est envoyé dans une unité de séparation de laquelle on extrait d'une part les normales et mono paraffines qui sont recyclées soit en entrée de la colonne, en mélange avec la charge fraîche, soit en entrée de la première unité d'isomérisation, en mélange avec le flux de soutirage latéral, et d'autre part un flux riche en paraffines di et tribranchées qui constitue l'isomérat produit.In a fourth variant of the process according to the invention, the overhead stream of the distillation column is sent to a separation unit from which the normal and mono-paraffins which are recycled either at the inlet of the column, on the one hand, are extracted on the one hand. mixing with the fresh feedstock, either at the inlet of the first isomerization unit, in admixture with the side feed stream, and on the other hand a stream rich in di- and tribranched paraffins which constitutes the isomerate produced.

L'unité de séparation utilisée pourra être basée sur toute technique connue de l'homme de l'art par exemple une unité d'adsorption sur tamis moléculaire telle que celle décrite dans la demande de brevet US2002/0045793 A1 . L'adsorbant utilisé dans ladite unité pourra être tout adsorbant connu de l'homme de l'art permettant de faire cette séparation, par exemple les adsorbants décrits dans le brevet US 6 353 144 , la demande de brevet FR 02/09841 (adsorbant non-homogène constitué d'au moins un cristal formé d'un coeur et d'une couche extérieure continue présentant une sélectivité diffusionnelle supérieure à 5) et la demande de brevet US2002/0045793 A1 . On peut également envisager d'utiliser un ou plusieurs modules membranaires pour cette séparation, comme décrit par exemple dans la demande de brevet EP-A1- 0 922 748 .The separation unit used may be based on any technique known to those skilled in the art, for example a molecular sieve adsorption unit such as that described in the patent application. US2002 / 0045793 A1 . The adsorbent used in said unit may be any adsorbent known to those skilled in the art to make this separation, for example the adsorbents described in the patent US 6,353,144 , the patent application FR 02/09841 (Non-homogeneous adsorbent consisting of at least one crystal formed of a core and a continuous outer layer having a diffusional selectivity greater than 5) and the patent application US2002 / 0045793 A1 . It is also conceivable to use one or more membrane modules for this separation, as described for example in the patent application. EP-A1-0192274 .

Pour chacune des variantes de l'invention, la colonne de distillation pourra éventuellement être du type colonne à paroi interne (divided-wall column dans la terminologie anglo-saxonne), qui est une technologie qui s'applique bien au cas où l'on a un soutirage latéral.For each of the variants of the invention, the distillation column may optionally be of the type column-inner wall (divided-wall column in English terminology), which is a technology that applies well in case one has a side racking.

Dans les exemples décrits ci-après, l'une des unités de séparation mise en jeu est alimentée par un mélange de différents flux dont l'un au moins est issu de la charge fraîche, et on extrait de cette unité de séparation d'une part les normales et mono paraffines qui sont recyclées en entrée d'une unité d'isomérisation, et d'autre part un flux riche en paraffines di et tribranchées et naphténiques qui alimente une colonne de distillation dont on extrait a) un flux de tête qui est l'isomérat produit, et b) un flux de fond à partir duquel on recycle à épuisement le toluène et le methylcyclohexane contenus dans la charge fraîche.In the examples described below, one of the separation units involved is supplied with a mixture of different streams, at least one of which comes from the fresh feedstock, and this separation unit is extracted from a feedstock. the normal and mono-paraffins which are recycled at the inlet of an isomerisation unit, and secondly a stream rich in di- and tribranched paraffins and naphthenic which feeds a distillation column which is extracted a) a flow of head which is the isomerate produced, and b) a bottom stream from which the toluene and methylcyclohexane contained in the fresh feed are exhaustively recycled.

On pourra tolérer jusqu'à 1 % poids de nC7 dans l'isomérat constituant le flux de tête mais si possible moins de 0,5 % pds.Up to 1% by weight of nC7 can be tolerated in the isomerate constituting the head flow but if possible less than 0.5% by weight.

Dans un exemple ne faisant pas partie de l'invention, la charge fraîche alimente une unité d'isomérisation, l'effluent d'isomérisation, après stabilisation, alimente l'unité de séparation de laquelle on extrait d'une part les normales et mono paraffines qui sont recyclées en entrée de l'unité d'isomérisation, en mélange avec la charge fraîche, et d'autre part un flux riche en paraffines di et tribranchées et en cycles naphténiques qui alimente la colonne de distillation dont le flux de tête constitue l'isomérat, et dont le flux de fond riche en naphténiques est envoyé en charge de l'unité d'ouverture de cycles, dont l'effluent est recyclé en entrée de l'unité d'isomérisation en mélange avec la charge fraîche et le recycle provenant de l'unité de séparation.In an example not forming part of the invention, the fresh feed feeds an isomerization unit, the isomerization effluent, after stabilization, feeds the separation unit from which on the one hand the normal and mono are extracted. paraffins which are recycled to the input of the isomerization unit, mixed with the fresh feed, and secondly a rich flow of di- and tribranched paraffins and naphthenic rings which feeds the distillation column, the top flow of which constitutes the isomerate, and whose naphthenic rich bottom stream is fed to the ring opening unit, the effluent of which is recycled to the inlet of the isomerization unit in admixture with the fresh feed and the feedstock. recycle from the separation unit.

Dans un exemple ne faisant pas partie de l'invention, la charge fraîche alimente, après stabilisation, l'unité de séparation de laquelle on extrait d'une part les normales et mono paraffines qui sont recyclées en entrée d'une unité d'isomérisation, et d'autre part un flux riche en paraffines di et tribranchées et en cycles naphténiques qui alimente la colonne de distillation dont le flux de tête constitue l'isomérat, et dont le flux de fond riche en naphténiques est envoyé en charge de l'unité d'ouverture de cycles, dont l'effluent est recyclé en mélange avec la charge fraîche et l'effluent de l'unité d'isomérisation en entrée de la stabilisation.In an example not forming part of the invention, the fresh feed feeds, after stabilization, the separation unit from which are extracted on the one hand the normal and mono-paraffins which are recycled to the input of an isomerization unit and on the other hand, a stream rich in di- and tribranched paraffins and in naphthenic rings which feeds the distillation column, the top flow of which constitutes the isomerate, and whose rich naphthenic bottom flow is fed into the feed. a ring opening unit, the effluent of which is recycled mixed with the fresh feedstock and the effluent of the isomerization unit at the inlet of the stabilization.

Dans un exemple ne faisant pas partie de l'invention, la charge fraîche alimente une unité d'ouverture de cycles, l'effluent de la dite unité alimente une unité d'isomérisation, l'effluent de l'unité d'isomérisation, après stabilisation, alimente l'unité de séparation de laquelle on extrait d'une part les normales et mono paraffines qui sont recyclées en entrée de l'unité d'isomérisation en mélange avec l'effluent de l'unité d'ouverture de cycles, et d'autre part un flux riche en paraffines di et tribranchées et en cycles naphténiques qui alimente la colonne de distillation dont le flux de tête constitue l'isomérat, et dont le flux de fond riche en naphténiques est recyclé en charge de l'unité d'ouverture de cycles en mélange avec la charge fraîche.In an example not forming part of the invention, the fresh feed feeds a unit for opening cycles, the effluent of said unit feeds an isomerization unit, the effluent of the isomerization unit, after stabilization feeds the separation unit from which are extracted on the one hand the normal and mono-paraffins which are recycled to the input of the isomerization unit mixed with the effluent of the ring-opening unit, and on the other hand, a stream rich in di- and tribranched paraffins and in naphthenic rings which feeds the distillation column, the top flow of which constitutes the isomerate, and whose rich naphthenic bottom stream is recycled in charge of the daphthenic unit. opening cycles in mixture with the fresh load.

Dans les exemples décrits ci-après, l'une des unités de séparation mise en jeu est une colonne de distillation alimentée par un mélange de différents flux dont l'un au moins est issu de la charge fraîche, dont on extrait a) un flux de tête qui alimente une seconde unité de séparation dont on extrait d'une part les normales et mono paraffines qui sont recyclées en entrée d'une des unités d'isomérisation, et d'autre part un flux riche en paraffines di et tribranchées qui est l'isomérat produit, et b) un flux de fond à partir duquel on recycle à épuisement le toluène et le méthylcyclohexane contenus dans la charge fraîche.In the examples described below, one of the separation units involved is a distillation column fed by a mixture of different streams, at least one of which is derived from the fresh feed, from which a flow is extracted. head which feeds a second separation unit which is extracted on the one hand normal and mono-paraffins which are recycled to the input of one of the isomerization units, and secondly a rich flow of di and tribranched paraffins which is the isomerate produced, and b) a bottom stream from which the toluene and methylcyclohexane contained in the fresh feed are exhaustively recycled.

On pourra tolérer jusqu'à 1 % poids de nC7 dans l'isomérat mais si possible moins de 0,5 % pds. Un exemple ne faisant pas partie de l'invention, la charge fraîche alimente une unité d'isomérisation, l'effluent d'isomérisation, après stabilisation, alimente la colonne de distillation dont le flux de tête alimente l'unité de séparation de laquelle on extrait d'une part les normales et mono paraffines qui sont recyclées en entrée de l'unité d'isomérisation, en mélange avec la charge fraîche, et d'autre part un flux riche en paraffines di et tribranchées qui constitue l'isomérat, le flux de fond de la colonne de distillation riche en naphténiques est envoyé en charge d'une unité d'ouverture de cycles dont l'effluent est recyclé en entrée de l'unité d'isomérisation en mélange avec la charge fraîche et le recycle provenant de l'unité de séparation.Up to 1% by weight of nC7 in the isomerate can be tolerated but, if possible, less than 0.5% by weight. An example not forming part of the invention, the fresh feed feeds an isomerization unit, the isomerization effluent, after stabilization, feeds the distillation column whose feed stream feeds the separation unit of which one extracts on the one hand the normal and mono-paraffins which are recycled at the input of the isomerization unit, mixed with the fresh feedstock, and on the other hand a stream rich in di- and tribranched paraffins which constitutes the isomerate, the bottom stream of the naphthenic rich distillation column is fed to a ring opening unit whose effluent is recycled to the inlet of the isomerization unit in admixture with the fresh feedstock and the recycle from the separation unit.

Dans un exemple ne faisant pas partie de l'invention, la charge fraîche alimente, après stabilisation, la colonne de distillation dont le flux de tête alimente l'unité de séparation de laquelle on extrait d'une part les normales et mono paraffines qui sont recyclées en entrée d'une première unité d'isomérisation, et d'autre part un flux riche en paraffines di et tribranchées qui constitue l'isomérat, le flux de fond de la colonne riche en naphténiques est envoyé en charge d'une unité d'ouverture de cycles dont l'effluent est envoyé en charge d'une seconde unité d'isomérisation dont l'effluent est recyclé en mélange avec la charge fraîche et l'effluent recyclé de la première unité d'isomérisation en entrée de la stabilisation.In an example which does not form part of the invention, the fresh feed feeds, after stabilization, the distillation column whose feed stream feeds the separation unit from which are extracted on the one hand the normal and mono-paraffins which are recycled at the inlet of a first isomerization unit, and secondly a stream rich in di- and tribranched paraffins which constitutes the isomerate, the bottom flow of the naphthenic rich column is fed into a unit of opening cycles whose effluent is sent in charge of a second isomerization unit whose effluent is recycled mixed with the fresh feedstock and the effluent recycled from the first isomerization unit at the inlet of the stabilization.

Dans un exemple ne faisant pas partie de l'invention, la charge fraîche alimente une unité d'ouverture de cycles, l'effluent de la dite unité alimente une unité d'isomérisation, l'effluent de cette unité d'isomérisation, après stabilisation, alimente la colonne de distillation dont le flux de tête alimente l'unité de séparation de laquelle on extrait d'une part les normales et mono paraffines qui sont recyclées en entrée de l'unité d'isomérisation, en mélange avec l'effluent de l'unité d'ouverture de cycles et d'autre part un flux riche en paraffines di et tribranchées qui constitue l'isomérat, le flux de fond de la colonne est recyclé en charge de l'unité d'ouverture de cycles en mélange avec la charge fraîche.In an example not forming part of the invention, the fresh feed feeds a unit of opening of cycles, the effluent of said unit feeds an isomerization unit, the effluent of this isomerization unit, after stabilization , feeds the distillation column whose head flow feeds the separation unit from which one extracts on the one hand the normal and mono-paraffins which are recycled to the input of the isomerisation unit, in mixing with the effluent of the ring opening unit and secondly a rich flow of di- and tribranched paraffins which constitutes the isomerate, the bottom flow of the column is recycled in charge of the unit of opening of cycles mixed with fresh feed.

Dans un exemple ne faisant pas partie de l'invention, la charge fraîche alimente une unité d'ouverture de cycles, l'effluent de la dite unité, après stabilisation, alimente la colonne de distillation dont le flux de tête alimente l'unité de séparation de laquelle on extrait d'une part les normales et mono paraffines qui sont envoyées en entrée d'une première unité d'isomérisation dont l'effluent est recyclé en entrée de stabilisation en mélange avec l'effluent de l'unité d'ouverture de cycles et d'autre part un flux riche en paraffines di et tribranchées qui constitue l'isomérat, le flux de fond de la colonne alimente une seconde unité d'isomérisation, dont l'effluent est recyclé en charge de l'unité d'ouverture de cycles en mélange avec la charge fraîche.In an example not forming part of the invention, the fresh feed feeds a unit for opening cycles, the effluent of said unit, after stabilization, feeds the distillation column, the feed of which feeds the feed unit. separation from which are extracted on the one hand the normal and mono-paraffins which are sent as input to a first isomerization unit whose effluent is recycled to the stabilization inlet mixed with the effluent of the opening unit of cycles and on the other hand a flow rich in di- and tribranched paraffins which constitutes the isomerate, the bottom flow of the column feeds a second isomerization unit, whose effluent is recycled in charge of the unit of opening of cycles mixed with fresh feed.

Au sens de la présente invention et des différentes variantes du procédé selon l'invention, on entend par flux "riche" en un composé, un flux dont la composition pondérale est telle que ledit composé représente au moins 50% poids, de préférence au moins 65 % poids et de manière encore plus préférée au moins 80% poids de la composition totale. L'hydrogénation du toluène peut être réalisée dans une unité d'hydrogénation spécifique. Cette unité peut être placée de manière à traiter l'ensemble de la charge fraîche, ou de manière à traiter uniquement la charge de l'unité d'ouverture de cycles ou d'une des unités d'isomérisation.Within the meaning of the present invention and of the various variants of the process according to the invention, the term "rich" stream is understood to mean a stream whose weight composition is such that said compound represents at least 50% by weight, preferably at least 65% by weight and even more preferably at least 80% by weight of the total composition. The hydrogenation of toluene can be carried out in a specific hydrogenation unit. This unit can be placed to process the entire fresh feed, or to process only the feed of the ring opening unit or one of the isomerization units.

La description détaillée de l'invention est faite au moyen de la figure 1 qui présente un schéma de procédé de l'invention dans une de ses variantes préférées. La description détaillée de cette variante inclut l'exemple qui l'illustre.The detailed description of the invention is made by means of the figure 1 which presents a process diagram of the invention in one of its preferred variants. The detailed description of this variant includes the example that illustrates it.

D'autres variantes sont possibles, mais ne seront pas toutes décrites de manière détaillée.Other variants are possible, but not all will be described in detail.

Dans l'exemple qui illustre la variante préférée (Cf figure 1), la charge à traiter (1) est introduite dans une colonne à distiller (A) comportant 88 plateaux réels au niveau du plateau 50. La charge fraîche (1) a dans l'exemple considéré la composition suivante (en % poids) et un débit massique donné ci-après : % poids diméthyl 2-3 butane 0,01 méthyl-2 pentane 0,10 méthyl-3 pentane 0,14 n-hexane 1,41 méthyl-cyclopentane 0,79 cyclohexane 1,64 benzène 0,18 triméthyl 2-2-3 butane 0,06 diméthyl 2-2 pentane 0,15 diméthyl 2-3 pentane 3,66 diméthyl 2-4 pentane 0,42 diméthyl 3-3 pentane 0,24 méthyl-2 hexane 9,39 méthyl-3 hexane 12,68 éthyl-3 pentane 1,16 n-heptane 31,20 diméthyl-1,1 cyclopentane 0,89 cis-diméthyl-1,3 cyclopentane 2,40 trans-diméthyl-1,3 cyclopentane 2,29 trans-diméthyl-1,2 cyclopentane 4,33 méthyl-cyclohexane 12,43 éthyl-cyclopentane 0,70 toluène 13,23 C8+ 0,50 débit total (kg /h) 11117 In the example that illustrates the preferred variant (Cf. figure 1 ), the charge to be treated (1) is introduced into a distillation column (A) comprising 88 actual trays at the plateau 50. The fresh batch (1) has in the example considered the following composition (in% by weight) and a mass flow rate given below:% by weight dimethyl 2-3 butane 0.01 2-methyl pentane 0.10 methyl-3 pentane 0.14 n-hexane 1.41 methyl-cyclopentane 0.79 cyclohexane 1.64 benzene 0.18 trimethyl 2-2-3 butane 0.06 dimethyl 2-2 pentane 0.15 dimethyl 2-3 pentane 3.66 dimethyl 2-4 pentane 0.42 dimethyl 3-3 pentane 0.24 2-methyl hexane 9.39 3-methyl hexane 12.68 ethyl-3 pentane 1.16 n-heptane 31,20 1,1-dimethylcyclopentane 0.89 cis-dimethyl-1,3 cyclopentane 2.40 1,3-trans-1,3-dimethylcyclopentane 2.29 1,2-trans-1,2-dimethylcyclopentane 4.33 methyl-cyclohexane 12.43 ethyl-cyclopentane 0.70 toluene 13.23 C 8+ 0.50 total flow (kg / h) 11117

En tête de la colonne (A) sort un flux (2) qui correspond à l'isomérat produit et dont la composition pondérale et le débit massique sont les suivants : isopentane 4,23 diméthyl 2-2 butane 0,22 diméthyl 2-3 butane 0,18 méthyl-2 pentane 0,83 méthyl-3 pentane 0,53 n-hexane 2,21 méthyl-cyclopentane 0,97 cyclohexane 1,93 benzène 0,18 triméthyl 2-2-3 butane 8,12 diméthyl 2-2 pentane 22,04 diméthyl 2-3 pentane 0,88 diméthyl 2-4 pentane 47,23 diméthyl 3-3 pentane 3,07 méthyl-2 hexane 4,34 méthyl-3 hexane 1,79 éthyl-3 pentane 0,06 n-heptane 0,50 diméthyl-1,1 cyclopentane 0,20 cis-diméthyl-1,3 cyclopentane 0,08 trans-diméthyl-1,3 cyclopentane 0,07 trans-diméthyl-1,2 cyclopentane 0,06 méthyl-cyclohexane 0,28 éthyl-cyclopentane 0,00 toluène 0,00 C8+ 0,00 débit total (kg /h) 9317 At the top of the column (A) flows a flow (2) which corresponds to the product isomerate and whose weight composition and mass flow rate are as follows: isopentane 4.23 dimethyl 2-2 butane 0.22 dimethyl 2-3 butane 0.18 2-methyl pentane 0.83 methyl-3 pentane 0.53 n-hexane 2.21 methyl-cyclopentane 0.97 cyclohexane 1.93 benzene 0.18 trimethyl 2-2-3 butane 8.12 dimethyl 2-2 pentane 22.04 dimethyl 2-3 pentane 0.88 dimethyl 2-4 pentane 47,23 dimethyl 3-3 pentane 3.07 2-methyl hexane 4.34 3-methyl hexane 1.79 ethyl-3 pentane 0.06 n-heptane 0.50 1,1-dimethylcyclopentane 0.20 cis-dimethyl-1,3 cyclopentane 0.08 1,3-trans-1,3-dimethylcyclopentane 0.07 1,2-trans-1,2-dimethylcyclopentane 0.06 methyl-cyclohexane 0.28 ethyl-cyclopentane 0.00 toluene 0.00 C 8+ 0.00 total flow (kg / h) 9317

Le RON de cet isomérat (flux 2) est de 84,2 et sa teneur en aromatiques est de 0,18 % pds. Au niveau du plateau 44 est soutiré un flux (3) contenant une majorité (au moins 70%) de normal-heptane et de paraffines en C7 monobranchées.The RON of this isomerate (stream 2) is 84.2 and its aromatic content is 0.18 wt%. At the tray 44 is drawn a stream (3) containing a majority (at least 70%) of normal-heptane and C 7 paraffins mono-branched.

Au niveau du fond de la colonne (A) est soutiré un flux (4) qui est un flux riche en methylcyclohexane, toluène et n-heptane.At the bottom of the column (A) is drawn a stream (4) which is a rich flow of methylcyclohexane, toluene and n-heptane.

Ce flux (4) est envoyé dans une unité d'hydrogénation spécifique du toluène (B) puis dans une unité d'ouverture de cycles (C) qui produit un effluent (5) contenant principalement un mélange de paraffines résultant pour partie de l'ouverture des cycles, ainsi que le méthyl-cyclohexane non converti, le toluène étant totalement hydrogéné.This stream (4) is sent to a toluene-specific hydrogenation unit (B) and then to a ring-opening unit (C) which produces an effluent (5) containing mainly a mixture of paraffins resulting in part from the opening of the rings, as well as unconverted methyl-cyclohexane, toluene being completely hydrogenated.

Le catalyseur utilisé pour l'unité d'ouverture de cycles pourra être tout catalyseur permettant de convertir par ouverture de cycle au moins 5% du méthylcyclohexane présent dans le mélange à traiter. Dans l'exemple illustrant la variante préférée, l'unité d'ouverture de cycles met en oeuvre un catalyseur à base d'iridium déposé sur alumine ou silice-alumine, tel que celui décrit dans la demande de brevet WO 02 /07881 .The catalyst used for the ring opening unit may be any catalyst for ring-opening conversion of at least 5% of the methylcyclohexane present in the mixture to be treated. In the example illustrating the preferred variant, the ring opening unit uses an iridium catalyst deposited on alumina or silica-alumina, such as that described in the patent application. WO 02/07881 .

L'unité d'ouverture de cycles est opérée dans les conditions suivantes :

  • Température = 300 °C
  • Pression = 14 bar.eff
  • PPH = 10 h-1
  • Ratio molaire hydrogène/hydrocarbure = 6 moles/mole
The opening unit of cycles is operated under the following conditions:
  • Temperature = 300 ° C
  • Pressure = 14 bar.eff
  • PPH = 10 h -1
  • Hydrogen / hydrocarbon molar ratio = 6 moles / mole

La composition pondérale et le débit massique (hors hydrogène) du flux (5) correspondant à l'effluent de l'unité d'ouverture de cycles sont les suivants : C5- 1,82 paraffines C5 3,69 paraffines C6 1,72 méthyl-cyclopentane 0,00 cyclohexane 0,00 benzène 0,00 paraffines C7 71,13 diméthyl-1,1 cyclopentane 0,39 cis-diméthyl-1,3 cyclopentane 0,37 trans-diméthyl-1,3 cyclopentane 0,40 trans-diméthyl-1,2 cyclopentane 0,40 méthyl-cyclohexane 19,18 éthyl-cyclopentane 0,39 toluène 0,00 C8+ 0,51 débit total (kg /h) 10962 The weight composition and the mass flow rate (excluding hydrogen) of the stream (5) corresponding to the effluent of the ring opening unit are as follows: C 5- 1.82 paraffins C 5 3.69 paraffins C 6 1.72 methyl-cyclopentane 0.00 cyclohexane 0.00 benzene 0.00 paraffins C 7 71.13 1,1-dimethylcyclopentane 0.39 cis-dimethyl-1,3 cyclopentane 0.37 1,3-trans-1,3-dimethylcyclopentane 0.40 1,2-trans-1,2-dimethylcyclopentane 0.40 methyl-cyclohexane 19.18 ethyl-cyclopentane 0.39 toluene 0.00 C 8+ 0.51 total flow (kg / h) 10962

Le flux (5) est mélangé avec le flux (3) pour donner un flux (6) qui est introduit dans une unité d'isomérisation (D) mettant en oeuvre un catalyseur à base de platine sur alumine chlorée tel que décrit dans la demande de brevet US2002/0002319 A1 .The stream (5) is mixed with the stream (3) to give a stream (6) which is introduced into an isomerization unit (D) using a platinum catalyst on chlorinated alumina as described in the application patent US2002 / 0002319 A1 .

L'unité d'isomérisation travaille aux conditions suivantes :

  • Température = 90 °C
  • Pression = 30 bar.eff
  • PPH = 1 h-1
  • Ratio molaire hydrogène/hydrocarbure = 0,2 mole/mole
The isomerization unit works under the following conditions:
  • Temperature = 90 ° C
  • Pressure = 30 bar.eff
  • PPH = 1 h -1
  • Hydrogen / hydrocarbon molar ratio = 0.2 mol / mol

La composition pondérale et le débit massique (hors hydrogène) du flux (7) correspondant à l'effluent de l'unité d'isomérisation sont les suivants : C5- 2,54 isopentane 0,56 diméthyl 2-2 butane 0,03 diméthyl 2-3 butane 0,02 méthyl-2 pentane 0,10 méthyl-3 pentane 0,05 n-hexane 0,12 méthyl-cyclopentane 0,04 cyclohexane 0,10 benzène 0,00 triméthyl 2-2-3 butane 1,63 diméthyl 2-2 pentane 3,26 diméthyl 2-3 pentane 4,08 diméthyl 2-4 pentane 8,16 diméthyl 3-3 pentane 4,08 méthyl-2 hexane 22,04 méthyl-3 hexane 16,32 éthyl-3 pentane 0,82 n-heptane 21,22 diméthyl-1,1 cyclopentane 0,33 cis-diméthyl-1,3 cyclopentane 0,32 trans-diméthyl-1,3 cyclopentane 0,34 trans-diméthyl-1,2 cyclopentane 0,32 méthyl-cyclohexane 13,20 éthyl-cyclopentane 0,32 toluène 0,00 C8+ 0,00 débit total (kg /h) 70847 The weight composition and the mass flow rate (excluding hydrogen) of the stream (7) corresponding to the effluent of the isomerization unit are as follows: C 5- 2.54 isopentane 0.56 dimethyl 2-2 butane 0.03 dimethyl 2-3 butane 0.02 2-methyl pentane 0.10 methyl-3 pentane 0.05 n-hexane 0.12 methyl-cyclopentane 0.04 cyclohexane 0.10 benzene 0.00 trimethyl 2-2-3 butane 1.63 dimethyl 2-2 pentane 3.26 dimethyl 2-3 pentane 4.08 dimethyl 2-4 pentane 8.16 dimethyl 3-3 pentane 4.08 2-methyl hexane 22.04 3-methyl hexane 16.32 ethyl-3 pentane 0.82 n-heptane 21,22 1,1-dimethylcyclopentane 0.33 cis-dimethyl-1,3 cyclopentane 0.32 1,3-trans-1,3-dimethylcyclopentane 0.34 1,2-trans-1,2-dimethylcyclopentane 0.32 methyl-cyclohexane 13,20 ethyl-cyclopentane 0.32 toluene 0.00 C 8+ 0.00 total flow (kg / h) 70847

L'effluent (7) de l'unité d'isomérisation est envoyé dans une colonne de stabilisation (E) d'où l'on sort en tête un flux (9) comprenant les gaz légers qui résultent des réactions de craquage au sein de l'unité d'isomérisation (coupe C5-) et en fond un flux (8) dont la composition est très proche de celle du flux (7) et qui est réintroduit en tête de la colonne (A) au niveau du plateau 12.The effluent (7) of the isomerization unit is sent to a stabilization column (E) from which a flow (9) comprising the light gases resulting from the cracking reactions within the isomerization unit (C 5- cut) and bottom a flow (8) whose composition is very close to that of the flow (7) and which is reintroduced at the top of the column (A) at the plateau 12 .

Le débit massique (hors hydrogène) du flux (9) s'élève à 1800 kg/h.The mass flow (excluding hydrogen) of the flow (9) amounts to 1800 kg / h.

On peut vérifier globalement que le débit massique du flux (1) est égal à la somme des débits massiques des flux (2) et (9).It can be checked globally that the mass flow rate of the flow (1) is equal to the sum of the mass flow rates of the flows (2) and (9).

Claims (6)

  1. Process for the production of an isomerate with a RON that is at least equal to 80, formed by at least 70% by weight of multibranched C7 paraffins and containing less than 1% by weight of aromatic compounds, starting with a fraction consisting mostly of hydrocarbons with 7 carbon atoms, and containing paraffins, naphthenes, and aromatic compounds, said process comprising at least one isomerization unit, at least one unit for opening naphthene rings, and at least one separation unit, wherein at least one of the separation units is a distillation column fed by a mixture of different streams, at least one of which is obtained from fresh feedstock, and from which is extracted a) a top stream which, after optional supplemental separation, provides the produced isomerate, b) a side stream that feeds, alone or in a mixture, one of the isomerization units, from which the normal paraffins and monobranched paraffins are converted to exhaustion, and c) a bottom stream, from which the toluene and the methyl cyclohexane contained in the fresh feedstock are recycled to exhaustion, wherein a first isomerization unit is fed by a side stream obtained from said distillation column, the isomerization effluent, after stabilization, being sent to said distillation column on a plate located above the side draw-off plate, wherein the fresh feedstock feeds the distillation column and wherein the ring opening unit is fed by the bottom stream from said column, the effluent from this ring opening unit being recycled either at the inlet of the isomerization unit, mixed with the side draw-off stream obtained from said column, or mixed with fresh feedstock, at the inlet of said column.
  2. Process according to claim 1, wherein the effluent of the ring opening unit feeds a second isomerization unit instead of being recycled at the entrance of the first isomerization unit or recycled in mixture with the fresh charge at the entrance of the distillation column and wherein the effluent of the second isomerization unit, after stabilization, feeds the distillation column in mixture with the fresh charge.
  3. Process according to one of claims 1 or 2, wherein the top stream from the distillation column is sent into a separation unit from which is extracted, on the one hand, the normal paraffins and mono-paraffins that are recycled either at the inlet of the column, mixed with fresh feedstock, or at the inlet of the first isomerization unit, mixed with the side draw-off stream and, on the other hand, a stream rich in di- and tri-branched paraffins.
  4. Process according to one of claims 1 to 3, wherein the distillation column is of the column type with an internal wall.
  5. Process according to one of claims 1 to 4, wherein the toluene is hydrogenated in a specific hydrogenation unit, this unit being placed either so as to treat all of the fresh feedstock, or so as to treat only the feedstock for the ring opening unit or one of the isomerization units.
  6. A process for the preparation of an isomerate according to any one of claims 1 to 5, wherein the isomerate is formed from at least 85% by weight of multiply branched C7-paraffins.
EP04291494.5A 2003-07-11 2004-06-14 improved isomerisation process of a C7 fraction with naphthenic rings opening Expired - Lifetime EP1496099B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR0308570A FR2857371B1 (en) 2003-07-11 2003-07-11 IMPROVED ISOMERIZATION METHOD OF A C7 CUT WITH OPENING OF THE NAPHTENIC CYCLES
FR0308570 2003-07-11

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FR2875507B1 (en) * 2004-09-22 2008-10-31 Inst Francais Du Petrole IMPROVED ISOMERIZATION METHOD OF A C7 CUT WITH COPRODUCTION OF A CUT RICH IN CYCLIC MOLECULES
US20150166438A1 (en) * 2013-12-12 2015-06-18 Uop Llc Processes and apparatuses for isomerizing hydrocarbons
FR3042190B1 (en) * 2015-10-09 2019-12-27 IFP Energies Nouvelles PROCESS FOR PRODUCING FUEL BASES
US11318452B2 (en) 2019-07-24 2022-05-03 Council Of Scientific & Industrial Research Single step process for the simultaneous production of aromatics, naphthenics and isoparaffins using transition metal functionalized zeolite based catalyst

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US2915571A (en) * 1957-11-13 1959-12-01 Universal Oil Prod Co Isomerization of saturated hydrocarbons
US4956521A (en) * 1988-10-06 1990-09-11 Uop Adsorption and isomerization of normal and mono-methyl paraffins
US5055633A (en) 1988-10-06 1991-10-08 Uop Adsorption and isomerization of normal and mono-methyl paraffins
US5334792A (en) * 1992-10-09 1994-08-02 Mobil Oil Corporation Combined paraffin isomerization/ring opening process for c5+naphtha
US5382731A (en) * 1993-07-22 1995-01-17 Mobil Oil Corp. Combined paraffin isomerization/ring opening process
US5463155A (en) * 1993-11-15 1995-10-31 Uop Upgrading of cyclic naphthas
FR2769622B1 (en) * 1997-10-14 1999-12-24 Inst Francais Du Petrole PROCESS FOR ISOMERIZING AROMATIC COMPOUNDS WITH EIGHT CARBON ATOMS
FR2771418B1 (en) * 1997-11-25 2001-02-02 Inst Francais Du Petrole PROCESS FOR SEPARATING A C5-C8 LOAD OR AN INTERMEDIATE LOAD, INTO THREE EFFLUENTS RESPECTIVELY RICH IN LINEAR, SINGLE-BRANCHED AND MULTI-BRANCHED PARAFFINS
FR2828205B1 (en) * 2001-08-06 2004-07-30 Inst Francais Du Petrole PROCESS FOR ISOMERIZING A C5-C8 CUTTING USING TWO PARALLEL REACTORS

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EP1496099A1 (en) 2005-01-12
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FR2857371B1 (en) 2007-08-24
US20050043576A1 (en) 2005-02-24

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