EP1640436B1 - Process of isomerisation of a C7 cut with coproduction of a cyclic cut comprising mainly methyl cyclohexane - Google Patents

Process of isomerisation of a C7 cut with coproduction of a cyclic cut comprising mainly methyl cyclohexane Download PDF

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EP1640436B1
EP1640436B1 EP05291856A EP05291856A EP1640436B1 EP 1640436 B1 EP1640436 B1 EP 1640436B1 EP 05291856 A EP05291856 A EP 05291856A EP 05291856 A EP05291856 A EP 05291856A EP 1640436 B1 EP1640436 B1 EP 1640436B1
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paraffins
unit
distillation column
isomerization
hand
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German (de)
French (fr)
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EP1640436A1 (en
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Paul Broutin
Dominique Casanave
Jean-Francois Joly
Elsa Jolimaitre
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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
    • C10G25/00—Refining of hydrocarbon oils in the absence of hydrogen, with solid sorbents
    • 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
    • C10G67/00—Treatment of hydrocarbon oils by at least one hydrotreatment process and at least one process for refining in the absence of hydrogen only
    • C10G67/02—Treatment of hydrocarbon oils by at least one hydrotreatment process and at least one process for refining in the absence of hydrogen only plural serial stages only
    • C10G67/06—Treatment of hydrocarbon oils by at least one hydrotreatment process and at least one process for refining in the absence of hydrogen only plural serial stages only including a sorption process as the refining step in the absence of hydrogen
    • 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 of paraffins and dehydrogenation of naphthenes.
  • 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 ratings for use in spark ignition engines, but for environmental reasons, their total content in gasoline is becoming increasingly limited.
  • the present invention relates more particularly to the isomerization of the C 7 -rich fraction obtained from atmospheric distillation naphtha
  • Table 1 gives the research octane number (RON) and the boiling points of the main hydrocarbon compounds present in the C7 cut obtained from atmospheric distillation naphtha: Table 1 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 e
  • 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.
  • nC7 in the isomerate Up to 1 wt.% Of nC7 in the isomerate and, if possible, less than 0.5 wt.% Can be tolerated.
  • the toluene present in the fresh feedstock can be totally hydrogenated to methylcyclohexane (MCH), either in a specific hydrogenation unit, or in the paraffin isomerization unit.
  • MCH methylcyclohexane
  • the C 7 isomerate obtained may contain up to 30% by weight of methyl-cyclohexane, a compound whose RON is less than 75, which significantly increases the RON of the C 7 isomerate. got.
  • MCH methylcyclohexane
  • the MCH can then be used either as a solvent or possibly reintroduced into the gasoline pool within the limits allowed by its relatively low RON.
  • the problem that 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 limited aromatic compounds, which makes it possible to anticipate the new regulations on the specifications of the gasoline pool.
  • RON search octane number
  • US Patent 6,338,791 discloses a separation process coupled to an isomerization reactor.
  • the separation process makes it possible to produce a fraction rich in multibranched paraffins and possibly in saturated or unsaturated cyclic compounds. This method therefore makes it possible to produce only one cut because the naphthenes and aromatics of the feedstock are not separated from the paraffins, and are therefore injected into the isomerization reactor.
  • the present invention must be placed in the more general context of the treatment of the naphtha fraction resulting from the atmospheric distillation of the crude.
  • FIG. 1 represents the process diagram according to the invention in its preferred variant comprising, upstream of the distillation column, a hydrogenation unit of toluene, and on the overhead flow coming from the distillation column, a paraffin separation unit. mono and di-connected.
  • the toluene hydrogenation unit and the mono and di paraffin separation unit connected to the overhead stream are optional and are shown in dotted line in FIG.
  • the fresh feedstock (1) is introduced into a distillation column (CD) from which a) a head stream (3) which gives the isomerized product is extracted, b) a side stream (4) which feeds one of the isomerisation units (IS) into a mixture and c) a bottom stream (5) which is introduced into a separation unit (SP1) of the normal paraffins on the one hand, and cyclic molecules of on the other hand, especially methylcyclohexane.
  • CD distillation column
  • SP1 separation unit
  • the flow (7) representing the effluent of the separation unit (SP1) consists of at least 90% mass of saturated or unsaturated cyclic molecules.
  • the stream (6) consisting of a majority of normal paraffins is reintroduced in admixture with the side stream (4) to constitute the stream (11) at the inlet of the isomerization unit (IS).
  • the effluent (8) of the isomerization unit (IS) is sent to a stabilization column (ST), from which a flow (9) is discharged which is sent back to the distillation column (CD) Ce flow (9) is reintroduced into the column (CD) on a tray located above the side draw plate so as to create a depletion of the normal paraffins whose content in the top flow (3) of the column (CD) will generally be less than 1% by weight and preferably less than 0.5% by weight.
  • the flow (10) leaving the top of the stabilization column constitutes a gaseous fraction which is sent to the fuel poool of the refinery.
  • the top stream (3) of the distillation column (CD) constitutes the isomerate.
  • the top stream (3) of the distillation column (CD) can be sent to a separation unit ( SP2) normal and mono-branched paraffins on the one hand, and branched di- and tri-paraffins on the other hand, the normal and mono-branched paraffins being reintroduced into the isomerization unit (IS).
  • SP2 a separation unit
  • the normal and mono-branched paraffins being reintroduced into the isomerization unit (IS).
  • the isomerate is constituted by the flow (12).
  • the fresh feedstock (1) may be introduced upstream of the distillation column (CD) in a toluene hydrogenation unit (HG) which makes it possible to convert the latter to methylcyclohexane.
  • the effluent of this hydrogenation unit constitutes the stream (2) and is sent as feed for the distillation column (CD).
  • the distillation column may be of the internal wall column type.
  • This type of column allows the fractionation by distillation of a feedstock in three distinct cuts, with a gain in energy required for the separation of about 20 - 30% relative to to a conventional distillation column.
  • the method which is the subject of the present invention thus comprises at least one distillation column (CD), at least one separation unit (SP1) of normal paraffins and cyclic molecules (methylcyclohexane and optionally toluene) making it possible to send to the isomerization unit (IS) that the paraffinic fraction of the C7 cut, and at least one isomerization unit (IS) fed by the lateral flow of the distillation column (CD) and by the normal paraffins from the unit separation (SP1).
  • CD distillation column
  • SP1 separation unit of normal paraffins and cyclic molecules (methylcyclohexane and optionally toluene)
  • the separation unit (SP1) between n-heptane and the cyclic molecules may use any technique known to those skilled in the art.
  • PSA pressure swing adsorption process
  • CCS simulated countercurrent separation
  • any adsorbent or adsorbent mixture having a selectivity in favor of the normal heptane or in favor of the cyclic molecules may be used, in particular an LTA-type zeolite. which selectively adsorbs normal paraffins and excludes molecules of larger molecular diameter, such as cyclic molecules saturated or not.
  • the adsorption separation (SP1) can be carried out in the gas phase by a PSA type process.
  • the operating temperature of the unit is between 150 and 400 ° C.
  • the desorbent used may be an inert gas, such as hydrogen or nitrogen or a hydrocarbon, such as C3-C6 paraffins.
  • Desorbents particularly well suited for this separation are normal paraffins.
  • One of the preferred desorbents is normal butane, whose boiling point is very far from that of nC7, and which can therefore be easily separated from this molecule.
  • Hydrogen is also a desorbent particularly well suited for this separation, since it can be directly recycled to the isomerization reactor with the desorbate (effluent from the desorption unit rich in nC7).
  • Such a separation unit makes it possible to produce MCH or an MCH + toluene mixture with a purity of between 95 and 99% by mass, and a yield of between 50 and 95%.
  • the adsorption separation (SP1) can be carried out in the liquid phase by a CCS type process.
  • the operating temperature of the unit is between 100 and 250 ° C.
  • the pressure of the column during the adsorption phase is between 2 and 20 bar.
  • the desorbent used is preferably a hydrocarbon, and may be in particular C3-C6 paraffins.
  • Desorbents particularly suitable for this separation are normal paraffins.
  • Such a CCS separation unit makes it possible to produce MCH or a MCH + toluene mixture with a purity of between 95 and 99.5% by mass, and a yield of between 50 and 98%.
  • the said separation (SP1) can also be carried out using one or more membrane modules.
  • Silicalite membranes such as those described in U.S. Patent 5,871,165 are known to possess a form selectivity in favor of normal paraffins.
  • the process also comprises at least one isomerization unit (IS) for converting normal and mono branched paraffins into multi-branched paraffins, such as the unit described in FIG. patent FR 01/10566 .
  • the isomerization catalyst used in said unit will be included in the group consisting of supported catalysts containing at least one halogen and at least one Group VIII metal, zeolitic catalysts containing at least one Group VIII metal, Friedel catalysts and Crafts, super acidic catalysts of type HPA on zirconia, WOx on zirconia, or sulphated zirconia.
  • the total pressure in the isomerization reaction zone is about 10 to 50 barg, the hourly space velocity being about 0.2 to 10 h -1.
  • the hydrogen / hydrocarbon molar ratio is between 0.06 and 30 mol / mol.
  • the temperature in the reaction zone is between 50 and 150 ° C, and preferably between 60 and 100 ° C.
  • the process optionally comprises a separating unit (SP2) fed by the column top flow (CD) and making it possible to separate the normal and mono branched paraffins on the one hand and the multi-branched paraffins on the other hand, so as to to recycle normal and mono-branched paraffins to the isomerization unit and maximize the production of multi-branched paraffins.
  • SP2 separating unit
  • CD column top flow
  • SP2 separation process
  • mono-branched paraffins and multi-branched paraffins can be based on any technique known to those skilled in the art.
  • a separation by distillation can be used, based on the difference in boiling temperatures of these different compounds (see Table 1).
  • 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 US Patents 6,353,144 , FR 02/09841 and the patent application US20020045793 Alcited above.
  • SP2 separation process of normal and mono-branched paraffins and multi-branched paraffins can also be based on a coupling of different techniques.
  • the separation is partially carried out by distillation to produce an intermediate feed enriched in di-branched paraffins and depleted in mono-branched paraffins.
  • This intermediate charge is then treated in an adsorption separation unit to obtain the desired final purity of di-branched paraffins.
  • the process which is the subject of the present invention may also comprise a unit for hydrogenation of toluene (HG) contained in the feed so as to convert this toluene to methylcyclohexane.
  • HG toluene
  • the hydrogenation catalyst used in said unit is a supported catalyst containing at least one Group VIII metal.
  • the total pressure in the reaction zone may be between 2 and 70 bar relative, and preferably between 5 and 50 bar relative.
  • the hydrogen / hydrocarbon molar ratio is between 1 and 15 mol / mol.
  • the temperature in the reaction zone is between 50 and 300 ° C, and preferably between 100 and 200 ° C.
  • the hourly volume velocity will be between 2 and 20 h-1.
  • This example illustrates one of the preferred variants of the invention in which the feed to be treated (1) is introduced into a hydrogenation reactor specific for toluene (HG) and then in a distillation column (CD) with 88 actual trays. The charge is introduced at the level of the tray 50.
  • HG toluene
  • CD distillation column
  • the lateral flow is extracted from the column at the plateau 44 and the recycling of the isomerization effluents (IS) after the stabilization (ST) is carried out at the plateau 15.
  • the fresh batch (1) has in the example considered the following composition (in% weight): dimethyl 2-3 butane 0.01 2-methyl pentane 0.13 methyl-3 pentane 0.16 n-hexane 1.41 methyl-cyclopentane 0.63 cyclohexane 1.71 benzene 0.37 trimethyl 2-2-3 butane 0.08 dimethyl 2-2 pentane 0.20 dimethyl 2-3 pentane 3.57 dimethyl 2-4 pentane 0.50 dimethyl 3-3 pentane 0.26 2-methyl hexane 8.97 3-methyl hexane 12.25 ethyl-3 pentane 1.14 n-heptane 31.39 1,1-dimethylcyclopentane 0.82 cis-dimethyl-1,3 cyclopentane 2.29 1,3-trans-1,3-dimethylcyclopentane 2.21 1,2-trans-1,2-dimethylcyclopentane 4.19 methyl-cyclohexane 12.96 ethyl-cyclopentane 0.
  • the separation unit between paraffins and naphthenes produces two effluents; an effluent (6) rich in n-heptane and an effluent (7) rich in methylcyclohexane.
  • the stream (6) is mixed with the stream (4) to give a stream (11) which constitutes the charge of the isomerization unit (IS) which uses a platinum catalyst on chlorinated alumina such as the described in the application US20020002319 A1 .
  • IS isomerization unit
  • the RON of this isomerate (stream 3) is 84.3 and its aromatic content is 0.00% wt.
  • composition of the stream (7) from the adsorption separation unit is as follows in weight percent: dimethyl 2-2 butane 0.01 dimethyl 2-3 butane 0.00 2-methyl pentane 0.0 methyl-3 pentane 0.0 n-hexane 0.0 methyl-cyclopentane 0.00 cyclohexane 0.0 benzene 0.0 trimethyl 2-2-3 butane 0.00 dimethyl 2-2 pentane 0.00 dimethyl 2-3 pentane 0.04 dimethyl 2-4 pentane 0.00 dimethyl 3-3 pentane 0.00 2-methyl hexane 0.15 3-methyl hexane 0.87 ethyl-3 pentane 0.22 n-heptane 1.02 1,1-dimethylcyclopentane 0.0 cis-dimethyl-1,3 cyclopentane 0.03 1,3-trans-1,3-dimethylcyclopentane 0.06 1,2-trans-1,2-dimethylcyclopentane 0.11 methyl-cyclohexane 94.
  • the summary table 3 below provides a comparison of the properties of the flows: ⁇ u> Table 3 ⁇ / u> stream (1) of example 1 flow (3) of Example 1 stream (7) of Example 1 % paraffins 60.56 94.11 2.31 % aromatics 13.09 0.00 0 % naphthenes 25.54 5.89 97.69 RON 50.7 84.3 73.9
  • Example 1 shows that the method of Example 1 according to the invention makes it possible to co-produce from the C7 cut (stream 1) resulting from atmospheric distillation, containing 13% aromatics and very low RON, an effluent (stream 3) very poor in aromatics and RON compatible with use in the gasoline pool and a naphthenic cut (stream 7) of high purity, recoverable as a solvent.
  • Example 1 the process as described in Example 1 (in particular the composition of the fresh feedstock is identical to that of stream (1)) is used, but the fresh feedstock is not treated in the hydrogenation reactor. toluene.
  • the flow composition (3) at the top of the distillation column CD is then the following in weight percentages: dimethyl 2-2 butane 0.09 dimethyl 2-3 butane 0.09 2-methyl pentane 0.51 methyl-3 pentane 0.42 n-hexane 2.40 methyl-cyclopentane 1.49 cyclohexane 3.93 benzene 0.0 trimethyl 2-2-3 butane 7.54 dimethyl 2-2 pentane 25.92 dimethyl 2-3 pentane 0.85 dimethyl 2-4 pentane 47.09 dimethyl 3-3 pentane 2.78 2-methyl hexane 4.19 3-methyl hexane 1.75 ethyl-3 pentane 0.07 n-heptane 0.5 1,1-dimethylcyclopentane 0.11 cis-dimethyl-1,3 cyclopentane 0.04 1,3-trans-1,3-dimethylcyclopentane 0.04 1,2-trans-1,2-dimethylcyclopentane 0.03 methyl-cyclohexane
  • composition of the stream (7) from the adsorption separation unit is as follows in percentages weight: dimethyl 2-2 butane 0.0 dimethyl 2-3 butane 0.02 2-methyl pentane 0.0 methyl-3 pentane 0.0 n-hexane 0.0 methyl-cyclopentane 0.00 cyclohexane 0.0 benzene 0.0 trimethyl 2-2-3 butane 0.00 dimethyl 2-2 pentane 0.00 dimethyl 2-3 pentane 0.01 dimethyl 2-4 pentane 0.00 dimethyl 3-3 pentane 0.00 2-methyl hexane 0.04 3-methyl hexane 0.35 ethyl-3 pentane 0.12 n-heptane 0.76 1,1-dimethylcyclopentane 0.0 cis-dimethyl-1,3 cyclopentane 0.03 1,3-trans-1,3-dimethylcyclopentane 0.05 1,2-trans-1,2-dimethylcyclopentane 0.11 methyl-cyclohexane 70.
  • Example 2 shows that the process of Example 2 according to the invention makes it possible to produce a paraffinic cut without aromatics (stream 3) and a cut rich in cyclic molecules (stream 7), both of RON compatible with a use in the gasoline pool. It is therefore possible to recombine the two streams (stream 3 + stream 7) to obtain a depleted cut in aromatics with respect to the feed (stream 1) and RON much higher than 80 which answers the problem of maintaining the specification. in RON with a limited content of aromatics.

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 du procédé d'isomérisation des paraffines normales en paraffines ramifiées.The suppression of lead alkyls in automotive gasolines and more recently the limitation of aromatic content in gasolines (35% in 2005 against 42% currently) has led to a development of branched paraffin production processes which have a much better index octane than linear paraffins, and in particular the process for isomerizing normal paraffins into branched paraffins.

Ce procédé revêt actuellement une importance croissante dans l'industrie pétrolière.This process is 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 des paraffines et de déshydrogénation des naphtènes.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 of paraffins and dehydrogenation of naphthenes.

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, leur teneur totale dans les essences se trouvent de plus en plus limitée.Aromatics have high octane ratings for use in spark ignition engines, but for environmental reasons, their total content in gasoline is becoming increasingly limited.

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.

La présente invention concerne plus particulièrement l'isomérisation de la fraction riche en C7 issue du naphta de distillation atmosphériqueThe present invention relates more particularly to the isomerization of the C 7 -rich fraction obtained from atmospheric distillation naphtha

Le tableau 1 ci-dessous donne l'indice d'octane recherche (RON) et les points d'ébullition des principaux composés hydrocarbonés présents dans la coupe C7 issue du naphta de distillation atmosphérique: Tableau 1 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 Table 1 below gives the research octane number (RON) and the boiling points of the main hydrocarbon compounds present in the C7 cut obtained from atmospheric distillation naphtha: Table 1 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 various C 7 isomers shows that the isomers of normal-heptane (nC 7 ) having 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.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.

Ces composés doivent donc être le plus possible transformés en paraffines di ou tribranchées dans le procédé d'isomérisation.These compounds must therefore be as much as possible converted into paraffins di or tribranched in the isomerization process.

Concernant le normal-heptane, la problématique est plus marquée encore. Son indice d'octane étant nul, il doit impérativement être converti à extinction dans le procédé d'isomérisation.Regarding normal-heptane, the problem is even more marked. Its octane number being zero, it must imperatively be converted to extinction in the isomerization process.

On pourra tolérer jusqu'à 1 % pds de nC7 dans l'isomérat et si possible moins de 0,5 % pds.Up to 1 wt.% Of nC7 in the isomerate and, if possible, less than 0.5 wt.% Can be tolerated.

Par ailleurs, le toluène présent dans la charge fraîche peut être totalement hydrogéné en méthyl-cyclohexane (MCH), soit dans une unité d'hydrogénation spécifique, soit dans l'unité d'isomérisation des paraffines.Moreover, the toluene present in the fresh feedstock can be totally hydrogenated to methylcyclohexane (MCH), either in a specific hydrogenation unit, or in the paraffin isomerization unit.

Or, le méthyl-cyclohexane présent dans la charge en quantité importante est très peu affecté par l'isomérisation, les catalyseurs d'isomérisation ne favorisant pas l'ouverture des cycles naphténiques dans leurs conditions habituelles de mise en oeuvre.However, the methyl-cyclohexane present in the feed in a large amount is very little affected by the isomerization, the isomerization catalysts not promoting the opening of naphthenic rings in their usual conditions of implementation.

Or, l'isomérat C7 obtenu peut contenir jusqu'à 30 % pds de méthyl-cyclohexane, composé dont le RON est inférieur à 75, ce qui grève notablement le RON de 1' isomérat C7. obtenu.However, the C 7 isomerate obtained may contain up to 30% by weight of methyl-cyclohexane, a compound whose RON is less than 75, which significantly increases the RON of the C 7 isomerate. got.

Il est donc intéressant de séparer le méthylcyclohexane ( MCH) de la charge paraffinique en C7 devant alimenter l'isomérisation.It is therefore advantageous to separate the methylcyclohexane (MCH) from the C7 paraffinic feedstock to feed the isomerization.

Le MCH peut ensuite être utilisé soit comme solvant, soit éventuellement être réintroduit dans le pool essence dans les limites autorisées par son RON relativement faible.The MCH can then be used either as a solvent or possibly reintroduced into the gasoline pool within the limits allowed by its relatively low RON.

Le problème que cherche à résoudre la présente invention est donc 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, ce qui permet d'anticiper la nouvelle réglementation sur les spécifications du pool essence.The problem that 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 limited aromatic compounds, which makes it possible to anticipate the new regulations on the specifications of the gasoline pool.

La solution proposée dans la présente invention consiste en un procédé de traitement d'une coupe C7, généralement issue d'une distillation atmosphérique, de manière à obtenir deux coupes:

  • une première coupe contenant majoritairement des paraffines qui est envoyée dans une unité d'isomérisation, et
  • une deuxième coupe contenant majoritairement du méthylcyclohexane ( MCH), qui pourra selon les besoins, être valorisée comme solvant ou éventuellement réintroduite au moins en partie dans le pool essence , tout en respectant la spécification sur le RON.
The solution proposed in the present invention consists of a process for treating a C7 cut, generally resulting from an atmospheric distillation, so as to obtain two cuts:
  • a first cut containing predominantly paraffins which is sent to an isomerization unit, and
  • a second section containing predominantly methylcyclohexane (MCH), which can be upgraded as a solvent or possibly reintroduced at least partially into the gasoline pool, while respecting the RON specification.

Examen de l'art antérieur :Examination of the prior art:

Il existe relativement peu de brevets concernant la valorisation de la coupe C7 par isomérisation, la plupart d'entre eux concernant le traitement par isomérisation de coupes C5-C6.There are relatively few patents concerning the valorization of the C7 cut by isomerization, most of them concerning the isomerization treatment of C5-C6 cuts.

De plus, aucun de ces procédés ne permet la production simultanée d'une coupe riche en molécules cycliques telle que le méthylcyclohexane.In addition, none of these methods allows the simultaneous production of a rich cyclic molecule cut such as methylcyclohexane.

le brevet US 6,069 289 décrit un procédé de séparation de paraffines multibranchées, éventuellement couplé à une isomérisation, mais la charge traitée ne contient pas de composés naphténiques et aromatiques.the US Patent 6,069,289 discloses a multi-branched paraffin separation process, optionally coupled to isomerization, but the treated feedstock does not contain naphthenic and aromatic compounds.

Le brevet US 6, 338 791 décrit un procédé de séparation couplé à un réacteur d'isomérisation.The US Patent 6,338,791 discloses a separation process coupled to an isomerization reactor.

Le procédé de séparation permet de produire une coupe riche en paraffines multibranchées et éventuellement en composés cycliques saturés ou insaturés. Ce procédé ne permet donc de produire qu'une seule coupe car les naphtènes et aromatiques de la charge ne sont pas séparés des paraffines, et sont donc injectés dans le réacteur d'isomérisation.The separation process makes it possible to produce a fraction rich in multibranched paraffins and possibly in saturated or unsaturated cyclic compounds. This method therefore makes it possible to produce only one cut because the naphthenes and aromatics of the feedstock are not separated from the paraffins, and are therefore injected into the isomerization reactor.

D'autres références sur des points particuliers seront données dans la description détaillée de l'invention.Other references on particular points will be given in the detailed description of the invention.

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

La présente invention doit être replacée dans le contexte plus général du traitement de la coupe naphta issue de la distillation atmosphérique du brut.The present invention must be placed in the more general context of the treatment of the naphtha fraction resulting from the atmospheric distillation of the crude.

La coupe naphta est généralement séparée en 3 fractions dans une colonne à distiller:

  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 paraffines di et tribranchées, et dont le nombre d'octane est compris entre 80 et 87.
  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.
    La présente invention porte sur le traitement de la fraction à 7 atomes de carbone issue du fractionnement précédent, mais étant donné les performances de la colonne de fractionnement du naphta, on pourra trouver dans la dite coupe C7 jusqu'à 10 % de composés plus légers à 6 atomes de carbone ou moins, et jusqu'à 10 % de composés plus lourds à 8 atomes de carbone et plus.
    La présente invention tient compte de ces composés adjacents à la coupe C7 proprement dite que l'on continuera à appeler par simplification "coupe C7".
    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% poids, et préférentiellement inférieure à 0,5 % poids, 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.
    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, c'est à dire au moins 60 % en poids, 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.
    L'invention s'applique à une coupe C7 issue d'un naphta de distillation atmosphérique, mais plus généralement elle s'applique à une coupe C7 ayant des proportions quelconques en paraffines, naphtènes et aromatiques. On entend par proportions quelconques, tout jeu de proportion dans lequel les familles paraffines, naphtènes et aromatiques sont présentes à raison d' au moins 1 % poids.
    Un des objectifs du procédé objet de la présente invention est de transformer cette coupe C7 en une coupe contenant majoritairement des paraffines en C7 multi-branchées, c'est à dire présentant un degré de branchement supérieur ou égal à deux.
    Un second objectif de la présente invention est de coproduire une coupe riche en molécules cycliques, naphténiques et éventuellement aromatiques.
    L'invention consiste donc en un procédé de production d'un isomérat de RON au moins égal à 80 et de coproduction d'une coupe naphtènique constituée majoritairement de méthylcyclohexane et éventuellement de toluène, à partir d'une coupe C7 d'hydrocarbures, contenant des paraffines, des naphtènes et des aromatiques en proportion quelconque, le dit procédé faisant appel à au moins une colonne de distillation permettant de séparer la charge en un flux de tête, un flux de fond et un flux latéral, une unité d'isomérisation, et au moins une unité de séparation des normales paraffines et des molécules cycliques, notamment le méthylcyclohexane, caractérisé en ce que la teneur en aromatiques de l'isomérat est inférieure à 1 % poids et préférentiellement inférieure à 0,5 % poids.
    Dans un mode de réalisation préféré de l'invention, la charge fraîche est introduite dans une colonne de distillation dont on extrait a) un flux de tête qui fournit l'isomérat produit, b) un flux latéral qui alimente en mélange une des unités d'isomérisation et c) un flux de fond qui est introduit dans une unité de séparation des normales paraffines d'une part, et des molécules cycliques d'autre part, notamment le méthylcyclohexane, les normales paraffines étant introduites en mélange avec le flux latéral dans au moins une unité d'isomérisation, et la coupe naphténique étant produite avec un niveau de pureté au moins égal à 90% masse.
    L'effluent de l'isomérisation après stabilisation est renvoyé à la colonne de distillation à un niveau (typiquement sur un plateau) situé au-dessus du niveau (plateau) de soutirage latéral.
    Le fait de recycler les normales paraffines contenues dans l'effluent de l'isomérisation ( IS) après passage dans une colonne de stabilisation ( ST), vers la colonne de distillation ( CD) de manière à minimiser leur teneur dans le flux de tête de la dite colonne. Compte tenu des points d'ébullition légèrement plus élevés des normales paraffines et des mono branchées, celles ci auront tendance à redescendre dans la colonne , tandis que les di et tribranchées de point d'ébullition légèrement plus faibles sortiront majoritairement en tête.
    Dans une variante de l'invention, le flux de tête de la colonne de distillation peut être envoyé dans une unité de séparation des paraffines normales et mono branchées d'une part, et des paraffines di et tri branchées d'autre part, les paraffines normales et mono branchées étant réintroduites dans l'unité d'isomérisation, et les paraffines di et tri branchées constituant l'isomérat.
    Dans une autre variante de l'invention, la charge fraîche peut être introduite en amont de la colonne à distiller dans une unité d'hydrogénation du toluène qui permet de transformer ce dernier en méthylcyclohexane, l'effluent de la dite unité d'hydrogénation étant introduit comme charge de la colonne de distillation.
    La colonne de distillation peut être du type colonne à paroi interne.
    Dans certains cas, l'unité de séparation des paraffines normales d'une part, et des molécules cycliques d'autre part, pourra être réalisée par un procédé d'adsorption.
    Dans d'autres cas, l'unité de séparation des paraffines normales d'une part, et des molécules cycliques d'autre part, pourra être réalisée par un procédé membranaire.
The naphtha section is generally separated into 3 fractions in a distillation column:
  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 with 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 of di- and tribranched paraffins, and whose number of octane is between 80 and 87.
  3. 3) a bottom fraction essentially containing the compounds with 8 or more carbon atoms which is sent to a catalytic reforming unit.
    The present invention relates to the treatment of the fraction with 7 carbon atoms resulting from the preceding fractionation, but given the performance of the naphtha fractionation column, it will be possible to find in said C 7 fraction up to 10% of compounds more light to 6 carbon atoms or less, and up to 10% heavier compounds with 8 or more carbon atoms.
    The present invention takes into account those compounds adjacent to the C7 section itself, which will continue to be called "C7 cut" simplification.
    The present invention relates to a process for producing multi-branched paraffins containing 7 carbon atoms, making it possible to obtain an isomerate having an octane number of at least 80 with an aromatic content of less than 1% by weight, and preferentially less than 0.5% by weight, from a feedstock comprising mainly 7-carbon hydrocarbons belonging to the families of paraffins, naphthenes and aromatics.
    In the remainder of the description, the abbreviation C 7 cut will be used to designate a filler comprising a major part of hydrocarbons containing 7 carbon atoms, ie at least 60% by weight, this C 7 cut being generally from a naphtha of first distillation, and having a chemical composition which varies with the origin of the naphtha cut.
    The invention applies to a C7 cut from an atmospheric distillation naphtha, but more generally it applies to a C7 cut having any proportions of paraffins, naphthenes and aromatics. By any proportion is meant any proportional set in which the paraffin, naphthenic and aromatic families are present in a proportion of at least 1% by weight.
    One of the objectives of the method which is the subject of the present invention is to transform this C 7 cut into a section containing predominantly C 7 multi-branched paraffins, ie having a degree of branching greater than or equal to two.
    A second objective of the present invention is to co-produce a fraction rich in cyclic, naphthenic and optionally aromatic molecules.
    The invention therefore consists of a process for producing an RON isomerate at least equal to 80 and for co-producing a naphthenic cut consisting predominantly of methylcyclohexane and optionally toluene, from a C7 cut of hydrocarbons, containing paraffins, naphthenes and aromatics in any proportion, said process using at least one distillation column for separating the feedstock into a feed stream, a bottom stream and a side stream, an isomerization unit, and at least one unit for separating normal paraffins and cyclic molecules, especially methylcyclohexane, characterized in that the aromatic content of the isomerate is less than 1% by weight and preferably less than 0.5% by weight.
    In a preferred embodiment of the invention, the fresh feedstock is introduced into a distillation column from which a) a head stream which supplies the isomerate produced is extracted, b) a side stream which feeds in mixture one of the d isomerization and c) a bottom flow which is introduced into a paraffin normal separation unit on the one hand, and cyclic molecules on the other hand, especially methylcyclohexane, the normal paraffins being introduced as a mixture with the side stream in at least one isomerization unit, and the naphthenic cut being produced with a purity level of at least 90% by weight.
    The isomerization effluent after stabilization is returned to the distillation column at a level (typically on a tray) located above the lateral draw-off (tray) level.
    Recycling the normal paraffins contained in the isomerization effluent (IS) after passing through a stabilization column (ST), to the distillation column (CD) so as to minimize their content in the head flow of the said column. Given the slightly higher boiling points of normal paraffins and mono branched, they will tend to fall back into the column, while di and tribranched boiling point slightly weaker out predominantly lead.
    In one variant of the invention, the overhead stream of the distillation column can be sent to a separation unit for normal and mono-branched paraffins on the one hand, and di- and tri-branched paraffins on the other hand, paraffins normal and branched mono being reintroduced into the isomerization unit, and the di- and tri-branched paraffins constituting the isomerate.
    In another variant of the invention, the fresh feed may be introduced upstream of the distillation column in a hydrogenation unit of toluene which makes it possible to convert the latter to methylcyclohexane, the effluent of said hydrogenation unit being introduced as the feedstock of the distillation column.
    The distillation column may be of the internal wall column type.
    In some cases, the normal paraffins separation unit, on the one hand, and cyclic molecules, on the other, may be carried out by an adsorption process.
    In other cases, the normal paraffins separation unit on the one hand, and cyclic molecules on the other hand, may be carried out by a membrane process.

Description sommaire de la figure:Brief description of the figure:

La figure 1 représente le schéma de procédé selon l'invention dans sa variante préférée comportant en amont de la colonne de distillation une unité d'hydrogénation du toluène, et sur le flux de tête issu de la colonne de distillation une unité de séparation des paraffines mono et di- branchées.FIG. 1 represents the process diagram according to the invention in its preferred variant comprising, upstream of the distillation column, a hydrogenation unit of toluene, and on the overhead flow coming from the distillation column, a paraffin separation unit. mono and di-connected.

L'unité d'hydrogénation du toluène et l'unité de séparation des paraffines mono et di branchées sur le flux de tête sont facultatives et sont indiquées en pointillé sur la figure 1.The toluene hydrogenation unit and the mono and di paraffin separation unit connected to the overhead stream are optional and are shown in dotted line in FIG.

Description détaillée de l'invention :Detailed description of the invention

La description détaillée de l'invention sera mieux comprise en suivant le schéma de procédé de la figure 1.The detailed description of the invention will be better understood by following the flow diagram of FIG.

La charge utilisée pour illustrer l'invention est une coupe C7 issue d'un naphta de distillation atmosphérique. Elle a la composition chimique donnée ci dessous :

  • normal-heptane de 20 à 40 % poids,
  • méthyl-2 hexane de 5 à 15 % poids,
  • méthyl-3 hexane de 10 à 20% poids,
  • méthyl-cyclohexane de 5 à 30 % poids,
  • toluène de 0 à 15 % poids.
The filler used to illustrate the invention is a C7 cut from an atmospheric distillation naphtha. It has the chemical composition given below:
  • normal-heptane of 20 to 40% by weight,
  • 2-methylhexane of 5 to 15% by weight,
  • 3-methylhexane of 10 to 20% by weight,
  • methylcyclohexane of 5 to 30% by weight,
  • toluene from 0 to 15% by weight.

Dans la configuration de base de l'invention, la charge fraîche( 1) est introduite dans une colonne de distillation (CD) dont on extrait a) un flux de tête ( 3) qui donne l'isomérat produit, b) un flux latéral ( 4) qui alimente en mélange une des unités d'isomérisation ( IS) et c) un flux de fond ( 5) qui est introduit dans une unité de séparation (SP1) des normales paraffines d'une part, et des molécules cycliques d'autre part, notamment le méthylcyclohexane.In the basic configuration of the invention, the fresh feedstock (1) is introduced into a distillation column (CD) from which a) a head stream (3) which gives the isomerized product is extracted, b) a side stream (4) which feeds one of the isomerisation units (IS) into a mixture and c) a bottom stream (5) which is introduced into a separation unit (SP1) of the normal paraffins on the one hand, and cyclic molecules of on the other hand, especially methylcyclohexane.

Le flux ( 7) représentant l'effluent de l'unité de séparation (SP1) est constituée d'au moins 90% masse de molécules cycliques saturées ou non.The flow (7) representing the effluent of the separation unit (SP1) consists of at least 90% mass of saturated or unsaturated cyclic molecules.

Le flux ( 6) constitué d'une majorité de normales paraffines est réintroduit en mélange avec le flux latéral ( 4) pour constituer le flux ( 11) à l'entrée de l'unité d'isomérisation ( IS)..The stream (6) consisting of a majority of normal paraffins is reintroduced in admixture with the side stream (4) to constitute the stream (11) at the inlet of the isomerization unit (IS).

L'effluent( 8) de l'unité d'isomérisation (IS) est envoyé dans une colonne de stabilisation ( ST), de laquelle on sort en fond un flux ( 9) qui est renvoyé à la colonne de distillation ( CD) Ce flux ( 9) est réintroduit dans la colonne ( CD) sur un plateau situé au-dessus du plateau de soutirage latéral de manière à créer un épuisement des normales paraffines dont la teneur dans le flux de tête (3) de la colonne ( CD) sera généralement inférieure à 1 % poids et préférentiellement inférieur à 0,5% poids.The effluent (8) of the isomerization unit (IS) is sent to a stabilization column (ST), from which a flow (9) is discharged which is sent back to the distillation column (CD) Ce flow (9) is reintroduced into the column (CD) on a tray located above the side draw plate so as to create a depletion of the normal paraffins whose content in the top flow (3) of the column (CD) will generally be less than 1% by weight and preferably less than 0.5% by weight.

Le flux (10) sortant en tête de la colonne de stabilisation constitueune fraction gazeuse qui est envoyé au poool combustible de la raffinerie.The flow (10) leaving the top of the stabilization column constitutes a gaseous fraction which is sent to the fuel poool of the refinery.

Le flux de tête( 3) de la colonne de distillation ( CD) constitue l'isomérat.The top stream (3) of the distillation column (CD) constitutes the isomerate.

Dans le but de maximiser la teneur en di et tri branchées dans l'isomérat, et selon une variante de l'invention, le flux de tête ( 3) de la colonne de distillation ( CD) peut être envoyé dans une unité de séparation ( SP2) des paraffines normales et mono branchées d'une part, et des paraffines di et tri branchées d'autre part, les paraffines normales et mono branchées étant réintroduites dans l'unité d'isomérisation ( IS). Dans cette variante l'isomérat est constitué par le flux (12).In order to maximize the branched di and tri content in the isomerate, and according to a variant of the invention, the top stream (3) of the distillation column (CD) can be sent to a separation unit ( SP2) normal and mono-branched paraffins on the one hand, and branched di- and tri-paraffins on the other hand, the normal and mono-branched paraffins being reintroduced into the isomerization unit (IS). In this variant the isomerate is constituted by the flow (12).

Selon une autre variante de l'invention, la charge fraîche( 1) pourra être introduite en amont de la colonne à distiller ( CD) dans une unité d'hydrogénation du toluène ( HG) qui permet de transformer ce dernier en méthylcyclohexane. L'effluent de cette unité d'hydrogénation constitue le flux ( 2) et est envoyé comme alimentation de la colonne à distiller ( CD).According to another variant of the invention, the fresh feedstock (1) may be introduced upstream of the distillation column (CD) in a toluene hydrogenation unit (HG) which makes it possible to convert the latter to methylcyclohexane. The effluent of this hydrogenation unit constitutes the stream (2) and is sent as feed for the distillation column (CD).

Enfin selon une autre variante de l'invention, la colonne de distillation peut être du type colonne à paroi interne.Finally, according to another variant of the invention, the distillation column may be of the internal wall column type.

Ce type de colonnes, bien connu de l'homme de l'art, permet le fractionnement par distillation d'une charge en trois coupes distinctes, avec un gain en énergie requise pour la séparation de l'ordre de 20 - 30 % par rapport à une colonne à distiller classique.This type of column, well known to those skilled in the art, allows the fractionation by distillation of a feedstock in three distinct cuts, with a gain in energy required for the separation of about 20 - 30% relative to to a conventional distillation column.

Le procédé, objet de la présente invention comprend donc au moins une colonne de distillation ( CD), au moins une unité de séparation ( SP1) des paraffines normales et des molécules cycliques (méthylcyclohexane et éventuellement toluène) permettant de n'envoyer à l'unité d'isomérisation ( IS) que la fraction paraffinique de la coupe C7, et au moins une unité d'isomérisation ( IS) alimentée par le flux latéral de la colonne à distiller ( CD) et par les paraffines normales issues de l'unité de séparation (SP1).The method which is the subject of the present invention thus comprises at least one distillation column (CD), at least one separation unit (SP1) of normal paraffins and cyclic molecules (methylcyclohexane and optionally toluene) making it possible to send to the isomerization unit (IS) that the paraffinic fraction of the C7 cut, and at least one isomerization unit (IS) fed by the lateral flow of the distillation column (CD) and by the normal paraffins from the unit separation (SP1).

L'unité de séparation ( SP1) entre le n-heptane et les molécules cycliques, principalement le méthylcyclohexane et éventuellement le toluène, pourra faire appel à toute technique connue de l'homme de l'art.The separation unit (SP1) between n-heptane and the cyclic molecules, mainly methylcyclohexane and optionally toluene, may use any technique known to those skilled in the art.

Parmi celles ci on peut citer le procédé d'adsorption par variation de pression connue sous l'abréviation PSA ou le procédé de séparation par contre courant simulé ( CCS).These include the pressure swing adsorption process known by the abbreviation PSA or the simulated countercurrent separation (CCS) method.

Dans le cas où la séparation (SP1) est réalisée par une unité d'adsorption, tout adsorbant ou mélange d'adsorbant possédant une sélectivité en faveur du normal heptane ou en faveur des molécules cycliques peut être utilisé, en particulier une zéolithe de type LTA qui adsorbe sélectivement les normales paraffines et exclut les molécules de plus gros diamètre moléculaire, telles que les molécules cycliques saturées ou non.In the case where the separation (SP1) is carried out by an adsorption unit, any adsorbent or adsorbent mixture having a selectivity in favor of the normal heptane or in favor of the cyclic molecules may be used, in particular an LTA-type zeolite. which selectively adsorbs normal paraffins and excludes molecules of larger molecular diameter, such as cyclic molecules saturated or not.

La séparation par adsorption (SP1) peut être réalisée en phase gazeuse par un procédé de type PSA. Dans ce cas, la température de fonctionnement de l'unité est comprise entre 150 et 400°C.The adsorption separation (SP1) can be carried out in the gas phase by a PSA type process. In this case, the operating temperature of the unit is between 150 and 400 ° C.

La pression de la colonne pendant la phase d'adsorption est comprise entre 2 et 20 bars ( 1 bar = 10 5 Pascals), et pendant la phase de désorption entre 0.5 et 3 bars.The pressure of the column during the adsorption phase is between 2 and 20 bars (1 bar = 10 5 Pascals), and during the desorption phase between 0.5 and 3 bars.

Le désorbant utilisé peut être un gaz inerte, tel que l'hydrogène ou l'azote ou un hydrocarbure, tel que les paraffines en C3-C6.The desorbent used may be an inert gas, such as hydrogen or nitrogen or a hydrocarbon, such as C3-C6 paraffins.

Des désorbants particulièrement bien adaptés pour cette séparation sont les normales paraffines.Desorbents particularly well suited for this separation are normal paraffins.

Un des désorbants préféré est le normal butane, dont la température d'ébullition est très éloignée de celle du nC7, et que l'on peut donc séparer facilement de cette molécule.One of the preferred desorbents is normal butane, whose boiling point is very far from that of nC7, and which can therefore be easily separated from this molecule.

L'hydrogène est également un désorbant particulièrement bien adapté pour cette séparation, car il peut être directement recyclé au réacteur d'isomérisation avec le désorbat ( effluent de l'unité de désorption riche en nC7).Hydrogen is also a desorbent particularly well suited for this separation, since it can be directly recycled to the isomerization reactor with the desorbate (effluent from the desorption unit rich in nC7).

Une telle unité de séparation (SP1) permet de produire du MCH ou un mélange MCH + toluène avec une pureté comprise entre 95 et 99 % massique, et un rendement compris entre 50 et 95%.Such a separation unit (SP1) makes it possible to produce MCH or an MCH + toluene mixture with a purity of between 95 and 99% by mass, and a yield of between 50 and 95%.

Alternativement, la séparation par adsorption (SP1) peut être réalisée en phase liquide par un procédé de type CCS. Dans ce cas, la température de fonctionnement de l'unité est comprise entre 100 et 250°C. La pression de la colonne pendant la phase d'adsorption est comprise entre 2 et 20 bars.Alternatively, the adsorption separation (SP1) can be carried out in the liquid phase by a CCS type process. In this case, the operating temperature of the unit is between 100 and 250 ° C. The pressure of the column during the adsorption phase is between 2 and 20 bar.

Le désorbant utilisé est préférentiellement un hydrocarbure, et peut être en particulier les paraffines en C3-C6.The desorbent used is preferably a hydrocarbon, and may be in particular C3-C6 paraffins.

Des désorbants particulièrement adaptés à cette séparation sont les normales-paraffines.Desorbents particularly suitable for this separation are normal paraffins.

Une telle unité de séparation par CCS permet de produire du MCH ou un mélange MCH + toluène avec une pureté comprise entre 95 et 99.5 % massique, et un rendement compris entre 50 et 98%.Such a CCS separation unit makes it possible to produce MCH or a MCH + toluene mixture with a purity of between 95 and 99.5% by mass, and a yield of between 50 and 98%.

On peut également réaliser la dite séparation ( SP1) en utilisant un ou plusieurs modules membranaires. Les membranes en silicalite, telles que celles décrites dans le brevet US 5, 871 165 sont connues pour posséder une sélectivité de forme en faveur des normales paraffines.The said separation (SP1) can also be carried out using one or more membrane modules. Silicalite membranes, such as those described in U.S. Patent 5,871,165 are known to possess a form selectivity in favor of normal paraffins.

On pourra également réaliser la séparation des paraffines et des molécules cycliques au moyen d' une extraction par solvant telle que celle décrite dans le brevet US 3, 169 998 qui est de type liquide/liquide, le solvant utilisé étant la gamma -butyrolactone.It will also be possible to separate the paraffins and the cyclic molecules by means of a solvent extraction such as that described in FIG. US Patent 3,169,998 which is of the liquid / liquid type, the solvent used being gamma-butyrolactone.

Le procédé comprend également au moins une unité d'isomérisation (IS) permettant de transformer les paraffines normales et mono branchées en paraffines multibranchées, telle que l'unité décrite dans le brevet FR 01/10566 . Le catalyseur d'isomérisation utilisé dans ladite unité sera compris dans le groupe constitué par les catalyseurs supportés contenant au moins un halogène et au moins un métal du groupe VIII, les catalyseurs zéolithiques contenant au moins un métal du groupe VIII, les catalyseurs de Friedel et Crafts, les catalyseurs super acides de type HPA sur zircone, WOx sur zircone, ou les zircones sulfatées.The process also comprises at least one isomerization unit (IS) for converting normal and mono branched paraffins into multi-branched paraffins, such as the unit described in FIG. patent FR 01/10566 . The isomerization catalyst used in said unit will be included in the group consisting of supported catalysts containing at least one halogen and at least one Group VIII metal, zeolitic catalysts containing at least one Group VIII metal, Friedel catalysts and Crafts, super acidic catalysts of type HPA on zirconia, WOx on zirconia, or sulphated zirconia.

La pression totale dans la zone réactionnelle d'isomérisation est d'environ 10 à 50 bars relatifs, la vitesse volumique horaire étant d'environ 0,2 à 10 h-1.The total pressure in the isomerization reaction zone is about 10 to 50 barg, the hourly space velocity being about 0.2 to 10 h -1.

Le rapport molaire hydrogène/hydrocarbure se situe entre 0,06 et 30 mole/mole.The hydrogen / hydrocarbon molar ratio is between 0.06 and 30 mol / mol.

La température dans la zone réactionnelle est comprise entre 50 et 150°C, et de manière préférée entre 60 et 100°C.The temperature in the reaction zone is between 50 and 150 ° C, and preferably between 60 and 100 ° C.

Le procédé comprend en option une unité de séparation ( SP2 ) alimenté par le flux de tête de la colonne ( CD) et permettant de séparer les paraffines normales et mono branchées d'une part et les paraffines multibranchées d'autre part, de manière à recycler vers l'unité d'isomérisation les paraffines normales et monobranchées et maximiser la production de paraffines multibranchées.The process optionally comprises a separating unit (SP2) fed by the column top flow (CD) and making it possible to separate the normal and mono branched paraffins on the one hand and the multi-branched paraffins on the other hand, so as to to recycle normal and mono-branched paraffins to the isomerization unit and maximize the production of multi-branched paraffins.

Le procédé de séparation ( SP2) des paraffines normales et mono branchées et des paraffines multibranchées peut être basé sur toute technique connue de l'homme de l'art.The separation process (SP2) of normal and mono-branched paraffins and multi-branched paraffins can be based on any technique known to those skilled in the art.

On peut en particulier utiliser une séparation par distillation, en se basant sur la différence de températures d'ébullition de ces différents composés (cf. Tableau 1).In particular, a separation by distillation can be used, based on the difference in boiling temperatures of these different compounds (see Table 1).

On peut également utiliser un procédé de séparation par adsorption sur tamis moléculaire telle que celui décrit dans la demande de brevet US20020045793 A1 .It is also possible to use a molecular sieve adsorption separation method such as that described in the patent application. US20020045793 A1 .

L'adsorbant utilisé dans ladite unité peut être tout adsorbant connu de l'homme de l'art permettant de faire cette séparation, par exemple les adsorbants décrits dans les brevets US 6 353 144 , FR 02/09841 et la demande de brevet US20020045793 Alcitée ci dessus.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 US Patents 6,353,144 , FR 02/09841 and the patent application US20020045793 Alcited above.

On peut également envisager d'utiliser un ou plusieurs modules membranaires pour cette séparation, comme décrit par exemple dans le brevet EP 0 922 748 .It is also possible to envisage using one or more membrane modules for this separation, as described, for example, in the EP 0 922 748 .

Le procédé de séparation ( SP2) des paraffines normales et mono branchées et des paraffines multibranchées peut également être basé sur un couplage de différentes techniques.The separation process (SP2) of normal and mono-branched paraffins and multi-branched paraffins can also be based on a coupling of different techniques.

En particulier, dans une des versions préférées du procédé, la séparation est partiellement réalisée par distillation pour produire une charge intermédiaire enrichie en paraffines di-branchées et appauvrie en paraffines monobranchéesIn particular, in one of the preferred versions of the process, the separation is partially carried out by distillation to produce an intermediate feed enriched in di-branched paraffins and depleted in mono-branched paraffins.

Cette charge intermédiaire est ensuite traitée dans une unité de séparation par adsorption pour obtenir la pureté finale souhaitée en paraffines di-branchées.This intermediate charge is then treated in an adsorption separation unit to obtain the desired final purity of di-branched paraffins.

Enfin, le procédé objet de la présente invention peut également comprendre une unité d'hydrogénation du toluène ( HG ) contenu dans la charge de manière à transformer ce toluène en méthylcyclohexane.Finally, the process which is the subject of the present invention may also comprise a unit for hydrogenation of toluene (HG) contained in the feed so as to convert this toluene to methylcyclohexane.

Le catalyseur d'hydrogénation utilisé dans ladite unité est un catalyseur supporté contenant au moins un métal du groupe VIII.The hydrogenation catalyst used in said unit is a supported catalyst containing at least one Group VIII metal.

La pression totale dans la zone réactionnelle peut être comprise entre 2 et 70 bars relatifs, et de manière préférée entre 5 et 50 bars relatifs.The total pressure in the reaction zone may be between 2 and 70 bar relative, and preferably between 5 and 50 bar relative.

Le rapport molaire hydrogène/ hydrocarbure est compris entre 1 et 15 moles/mole.The hydrogen / hydrocarbon molar ratio is between 1 and 15 mol / mol.

La température dans la zone réactionnelle est comprise entre 50 et 300°C, et de manière préférée, entre 100 et 200°C. La vitesse volumique horaire sera comprise entre 2 et 20 h-1.The temperature in the reaction zone is between 50 and 300 ° C, and preferably between 100 and 200 ° C. The hourly volume velocity will be between 2 and 20 h-1.

Exemple 1Example 1

Cet exemple illustre une des variantes préférées de l'invention dans laquelle la charge à traiter (1) est introduite dans un réacteur d'hydrogénation spécifique du toluène (HG) puis dans une colonne à distiller (CD) comportant 88 plateaux réels. L'introduction de la charge est réalisée au niveau du plateau 50.This example illustrates one of the preferred variants of the invention in which the feed to be treated (1) is introduced into a hydrogenation reactor specific for toluene (HG) and then in a distillation column (CD) with 88 actual trays. The charge is introduced at the level of the tray 50.

Le flux latéral est extrait de la colonne au niveau du plateau 44 et le recyclage des effluents de l'isomérisation ( IS) après la stabilisation ( ST) est effectué au niveau du plateau 15.The lateral flow is extracted from the column at the plateau 44 and the recycling of the isomerization effluents (IS) after the stabilization (ST) is carried out at the plateau 15.

Le réacteur d'hydrogénation du toluène travaille aux conditions opératoires suivantes:

  • T = 160°C
  • P = 5 bars relatifs
  • Rapport molaire hydrogène/hydrocarbure = 5 moles/mole
  • VVH=5 h-1
avec un catalyseur à base de Pt sur alumine.The hydrogenation reactor of toluene works under the following operating conditions:
  • T = 160 ° C
  • P = 5 bars relative
  • Hydrogen / hydrocarbon molar ratio = 5 moles / mole
  • VVH = 5 h-1
with a catalyst based on Pt on alumina.

La charge fraîche (1) a dans l'exemple considéré la composition suivante (en % poids): diméthyl 2-3 butane 0,01 méthyl-2 pentane 0,13 méthyl-3 pentane 0,16 n-hexane 1,41 méthyl-cyclopentane 0,63 cyclohexane 1,71 benzène 0,37 triméthyl 2-2-3 butane 0,08 diméthyl 2-2 pentane 0,20 diméthyl 2-3 pentane 3,57 diméthyl 2-4 pentane 0,50 diméthyl 3-3 pentane 0,26 méthyl-2 hexane 8.97 méthyl-3 hexane 12,25 éthyl-3 pentane 1,14 n-heptane 31,39 diméthyl-1,1 cyclopentane 0,82 cis-diméthyl-1,3 cyclopentane 2,29 trans-diméthyl-1,3 cyclopentane 2,21 trans-diméthyl-1,2 cyclopentane 4,19 méthyl-cyclohexane 12,96 éthyl-cyclopentane 0,73 toluène 13,52 C8+ 0,50 The fresh batch (1) has in the example considered the following composition (in% weight): dimethyl 2-3 butane 0.01 2-methyl pentane 0.13 methyl-3 pentane 0.16 n-hexane 1.41 methyl-cyclopentane 0.63 cyclohexane 1.71 benzene 0.37 trimethyl 2-2-3 butane 0.08 dimethyl 2-2 pentane 0.20 dimethyl 2-3 pentane 3.57 dimethyl 2-4 pentane 0.50 dimethyl 3-3 pentane 0.26 2-methyl hexane 8.97 3-methyl hexane 12.25 ethyl-3 pentane 1.14 n-heptane 31.39 1,1-dimethylcyclopentane 0.82 cis-dimethyl-1,3 cyclopentane 2.29 1,3-trans-1,3-dimethylcyclopentane 2.21 1,2-trans-1,2-dimethylcyclopentane 4.19 methyl-cyclohexane 12.96 ethyl-cyclopentane 0.73 toluene 13.52 C 8+ 0.50

L'effluent du réacteur d'hydrogénation du toluène est envoyé dans une colonne de distillation (CD) de laquelle on extrait 3 flux:

  • un flux de tête ( 3) qui correspond à l'isomérat produit.
  • un flux latéral (4) contenant une majorité ( au moins 70 %) de normal-heptane et de paraffines en C7 monobranchées qui va alimenter l'unité d'isomérisation.
  • un flux de fond (5), riche en méthylcyclohexane et en n-heptane qui est envoyé dans une unité de séparation entre les paraffines et les naphtènes.
The effluent from the hydrogenation reactor of toluene is sent to a distillation column (CD) from which 3 streams are extracted:
  • a head flow (3) which corresponds to the product isomerate.
  • a side stream (4) containing a majority (at least 70%) of normal-heptane and C7 mono-branched paraffins which will feed the isomerization unit.
  • a bottom stream (5) rich in methylcyclohexane and n-heptane which is sent to a separation unit between paraffins and naphthenes.

L'unité de séparation entre les paraffines et les naphtènes produit deux effluents; un effluent ( 6) riche en en n-heptane et un effluent ( 7) riche en méthylcyclohexane.The separation unit between paraffins and naphthenes produces two effluents; an effluent (6) rich in n-heptane and an effluent (7) rich in methylcyclohexane.

Le flux (6) est mélangé avec le flux (4) pour donner un flux (11) qui constitue la charge de l'unité d'isomérisation (IS) qui met en oeuvre un catalyseur à base de platine sur alumine chlorée tel que celui décrit dans la demande US20020002319 A1 .The stream (6) is mixed with the stream (4) to give a stream (11) which constitutes the charge of the isomerization unit (IS) which uses a platinum catalyst on chlorinated alumina such as the described in the application US20020002319 A1 .

L'unité d'isomérisation travaille aux conditions suivantes:

  • température: 90°C
  • Pression: 30 bars effectifs
  • PPH=1 h-1
  • Rapport molaire hydrogène/hydrocarbure = 0,2 mole/mole.
The isomerization unit works under the following conditions:
  • temperature: 90 ° C
  • Pressure: 30 effective bars
  • PPH = 1 hr-1
  • Hydrogen / hydrocarbon molar ratio = 0.2 mol / mol.

En tête de la colonne (CD) sort un flux (3) qui correspond à l'isomérat produit dont la composition pondérale et le débit massique sont les suivants : isopentane 0 diméthyl 2-2 butane 0,01 diméthyl 2-3 butane 0,01 méthyl-2 pentane 0,52 méthyl-3 pentane 0,42 n-hexane 2,37 méthyl-cyclopentane 1,43 cyclohexane 3,91 benzène 0,00 triméthyl 2-2-3 butane 7,38 diméthyl 2-2 pentane 26,39 diméthyl 2-3 pentane 0,82 diméthyl 2-4 pentane 47,01 diméthyl 3-3 pentane 2,62 méthyl-2 hexane 4,09 méthyl-3 hexane 1,73 éthyl-3 pentane 0,06 n-heptane 0,50 diméthyl-1,1 cyclopentane 0,15 cis-diméthyl-1,3 cyclopentane 0,06 trans-diméthyl-1,3 cyclopentane 0,05 trans-diméthyl-1,2 cyclopentane 0,05 méthyl-cyclohexane 0,24 éthyl-cyclopentane 0,00 toluène 0,00 C8+ 0,00 At the top of the column (CD) comes a stream (3) which corresponds to the product isomerate whose weight composition and mass flow rate are as follows: isopentane 0 dimethyl 2-2 butane 0.01 dimethyl 2-3 butane 0.01 2-methyl pentane 0.52 methyl-3 pentane 0.42 n-hexane 2.37 methyl-cyclopentane 1.43 cyclohexane 3.91 benzene 0.00 trimethyl 2-2-3 butane 7.38 dimethyl 2-2 pentane 26.39 dimethyl 2-3 pentane 0.82 dimethyl 2-4 pentane 47,01 dimethyl 3-3 pentane 2.62 2-methyl hexane 4.09 3-methyl hexane 1.73 ethyl-3 pentane 0.06 n-heptane 0.50 1,1-dimethylcyclopentane 0.15 cis-dimethyl-1,3 cyclopentane 0.06 1,3-trans-1,3-dimethylcyclopentane 0.05 1,2-trans-1,2-dimethylcyclopentane 0.05 methyl-cyclohexane 0.24 ethyl-cyclopentane 0.00 toluene 0.00 C 8+ 0.00

Le RON de cet isomérat (flux 3) est de 84,3 et sa teneur en aromatiques est de 0,00 % pds.The RON of this isomerate (stream 3) is 84.3 and its aromatic content is 0.00% wt.

La composition du flux (7) issu de l'unité de séparation par adsorption est la suivante en pourcents poids : diméthyl 2-2 butane 0,01 diméthyl 2-3 butane 0,00 méthyl-2 pentane 0,0 méthyl-3 pentane 0,0 n-hexane 0,0 méthyl-cyclopentane 0,00 cyclohexane 0,0 benzène 0,0 triméthyl 2-2-3 butane 0,00 diméthyl 2-2 pentane 0,00 diméthyl 2-3 pentane 0,04 diméthyl 2-4 pentane 0,00 diméthyl 3-3 pentane 0,00 méthyl-2 hexane 0,15 méthyl-3 hexane 0,87 éthyl-3 pentane 0,22 n-heptane 1.02 diméthyl-1,1 cyclopentane 0,0 cis-diméthyl-1,3 cyclopentane 0,03 trans-diméthyl-1,3 cyclopentane 0,06 trans-diméthyl-1,2 cyclopentane 0,11 méthyl-cyclohexane 94,78 éthyl-cyclopentane 2,72 toluène 0,00 C8+ 0,00 The composition of the stream (7) from the adsorption separation unit is as follows in weight percent: dimethyl 2-2 butane 0.01 dimethyl 2-3 butane 0.00 2-methyl pentane 0.0 methyl-3 pentane 0.0 n-hexane 0.0 methyl-cyclopentane 0.00 cyclohexane 0.0 benzene 0.0 trimethyl 2-2-3 butane 0.00 dimethyl 2-2 pentane 0.00 dimethyl 2-3 pentane 0.04 dimethyl 2-4 pentane 0.00 dimethyl 3-3 pentane 0.00 2-methyl hexane 0.15 3-methyl hexane 0.87 ethyl-3 pentane 0.22 n-heptane 1.02 1,1-dimethylcyclopentane 0.0 cis-dimethyl-1,3 cyclopentane 0.03 1,3-trans-1,3-dimethylcyclopentane 0.06 1,2-trans-1,2-dimethylcyclopentane 0.11 methyl-cyclohexane 94.78 ethyl-cyclopentane 2.72 toluene 0.00 C 8 + 0.00

Les valeurs de débits massiques des principaux flux sont donnés dans le tableau 2 ci dessous: Tableau 2 flux (1) flux (3) flux (7) débit massique (kg/h) 11000 5540 4155 The mass flow values of the main flows are given in Table 2 below: <U> Table 2 </ u> flow (1) flow (3) flow (7) mass flow (kg / h) 11000 5540 4155

Le tableau récapitulatif 3 ci dessous fournit une comparaison des propriétés des flux : Tableau 3 flux (1) de l'exemple 1 flux (3) de l'exemple 1 flux (7) de l'exemple 1 % paraffines 60.56 94.11 2.31 % aromatiques 13.09 0.00 0 % naphtènes 25.54 5.89 97.69 RON 50.7 84.3 73.9 The summary table 3 below provides a comparison of the properties of the flows: <u> Table 3 </ u> stream (1) of example 1 flow (3) of Example 1 stream (7) of Example 1 % paraffins 60.56 94.11 2.31 % aromatics 13.09 0.00 0 % naphthenes 25.54 5.89 97.69 RON 50.7 84.3 73.9

Le tableau 3 ci-dessus montre que le procédé de l'exemple 1 selon l'invention permet de coproduire à partir de la coupe C7( flux 1) issue de la distillation atmosphérique, contenant 13% d'aromatiques et de RON très faible, un effluent ( flux 3) très appauvri en aromatiques et de RON compatible avec une utilisation dans le pool essence et une coupe naphténique ( flux 7) de haute pureté, valorisable en tant que solvant.Table 3 above shows that the method of Example 1 according to the invention makes it possible to co-produce from the C7 cut (stream 1) resulting from atmospheric distillation, containing 13% aromatics and very low RON, an effluent (stream 3) very poor in aromatics and RON compatible with use in the gasoline pool and a naphthenic cut (stream 7) of high purity, recoverable as a solvent.

Exemple 2 :Example 2

Dans cet exemple, on reprend le procédé tel que décrit dans l'exemple 1 (en particulier la composition de la charge fraîche est identique à celle du flux (1)), mais en ne traitant pas la charge fraîche dans le réacteur d'hydrogénation du toluène.In this example, the process as described in Example 1 (in particular the composition of the fresh feedstock is identical to that of stream (1)) is used, but the fresh feedstock is not treated in the hydrogenation reactor. toluene.

La composition du flux (3) en tête de la colonne à distiller CD est alors la suivante en pourcentages poids : diméthyl 2-2 butane 0,09 diméthyl 2-3 butane 0,09 méthyl-2 pentane 0,51 méthyl-3 pentane 0,42 n-hexane 2,40 méthyl-cyclopentane 1,49 cyclohexane 3,93 benzène 0,0 triméthyl 2-2-3 butane 7,54 diméthyl 2-2 pentane 25,92 diméthyl 2-3 pentane 0,85 diméthyl 2-4 pentane 47,09 diméthyl 3-3 pentane 2,78 méthyl-2 hexane 4,19 méthyl-3 hexane 1,75 éthyl-3 pentane 0,07 n-heptane 0,5 diméthyl-1,1 cyclopentane 0,11 cis-diméthyl-1,3 cyclopentane 0,04 trans-diméthyl-1,3 cyclopentane 0,04 trans-diméthyl-1,2 cyclopentane 0,03 méthyl-cyclohexane 0,15 éthyl-cyclopentane 0,01 toluène 0,00 C8+ 0,00 The flow composition (3) at the top of the distillation column CD is then the following in weight percentages: dimethyl 2-2 butane 0.09 dimethyl 2-3 butane 0.09 2-methyl pentane 0.51 methyl-3 pentane 0.42 n-hexane 2.40 methyl-cyclopentane 1.49 cyclohexane 3.93 benzene 0.0 trimethyl 2-2-3 butane 7.54 dimethyl 2-2 pentane 25.92 dimethyl 2-3 pentane 0.85 dimethyl 2-4 pentane 47.09 dimethyl 3-3 pentane 2.78 2-methyl hexane 4.19 3-methyl hexane 1.75 ethyl-3 pentane 0.07 n-heptane 0.5 1,1-dimethylcyclopentane 0.11 cis-dimethyl-1,3 cyclopentane 0.04 1,3-trans-1,3-dimethylcyclopentane 0.04 1,2-trans-1,2-dimethylcyclopentane 0.03 methyl-cyclohexane 0.15 ethyl-cyclopentane 0.01 toluene 0.00 C 8+ 0.00

La composition du flux (7) issu de l'unité de séparation par adsorption est la suivante en pourcentages poids: diméthyl 2-2 butane 0,0 diméthyl 2-3 butane 0,02 méthyl-2 pentane 0,0 méthyl-3 pentane 0,0 n-hexane 0,0 méthyl-cyclopentane 0,00 cyclohexane 0,0 benzène 0,0 triméthyl 2-2-3 butane 0,00 diméthyl 2-2 pentane 0,00 diméthyl 2-3 pentane 0,01 diméthyl 2-4 pentane 0,00 diméthyl 3-3 pentane 0,00 méthyl-2 hexane 0,04 méthyl-3 hexane 0,35 éthyl-3 pentane 0,12 n-heptane 0,76 diméthyl-1,1 cyclopentane 0,0 cis-diméthyl-1,3 cyclopentane 0,03 trans-diméthyl-1,3 cyclopentane 0,05 trans-diméthyl-1,2 cyclopentane 0,11 méthyl-cyclohexane 70,22 éthyl-cyclopentane 2,96 toluène 25,34 C8+ 0,00 The composition of the stream (7) from the adsorption separation unit is as follows in percentages weight: dimethyl 2-2 butane 0.0 dimethyl 2-3 butane 0.02 2-methyl pentane 0.0 methyl-3 pentane 0.0 n-hexane 0.0 methyl-cyclopentane 0.00 cyclohexane 0.0 benzene 0.0 trimethyl 2-2-3 butane 0.00 dimethyl 2-2 pentane 0.00 dimethyl 2-3 pentane 0.01 dimethyl 2-4 pentane 0.00 dimethyl 3-3 pentane 0.00 2-methyl hexane 0.04 3-methyl hexane 0.35 ethyl-3 pentane 0.12 n-heptane 0.76 1,1-dimethylcyclopentane 0.0 cis-dimethyl-1,3 cyclopentane 0.03 1,3-trans-1,3-dimethylcyclopentane 0.05 1,2-trans-1,2-dimethylcyclopentane 0.11 methyl-cyclohexane 70.22 ethyl-cyclopentane 2.96 toluene 25.34 C 8 + 0.00

Les valeurs de débits massiques des principaux flux sont donnés dans le tableau 4 ci dessous: Tableau 4 flux (1) flux (3) flux (7) débit massique (kg/h) 11000 5509 4053 The mass flow values of the main flows are given in Table 4 below: <u> Table 4 </ u> flow (1) flow (3) flow (7) mass flow (kg / h) 11000 5509 4053

Comparaison des propriétés des flux : Tableau 5 flux (1) de l'exemple 2 flux (3) de l'exemple 2 flux (7) de l'exemple 2 flux (3) + (7) de l'exemple 2 % paraffines 60.56 94.06 1.29 54.81 % aromatiques 13.09 0.00 25.34 10.74 % naphtènes 25.54 5.94 73.37 34.45 RON 50.7 84.1 82.8 83.5 Comparison of stream properties: <u> Table 5 </ u> flow (1) of example 2 flow (3) of Example 2 stream (7) of Example 2 flow (3) + (7) of Example 2 % paraffins 60.56 94.06 1.29 54.81 % aromatics 13.09 0.00 25.34 10.74 % naphthenes 25.54 5.94 73.37 34.45 RON 50.7 84.1 82.8 83.5

Le tableau 5 ci-dessus montre que le procédé de l'exemple 2 selon l'invention permet de produire une coupe paraffinique sans aromatiques ( flux 3) et une coupe riche en molécules cycliques ( flux 7), toutes deux de RON compatible avec une utilisation dans le pool essence. Il est donc possible de recombiner les deux flux ( flux 3 + flux 7) pour obtenir une coupe appauvrie en aromatiques par rapport à la charge (flux 1) et de RON nettement supérieur à 80 ce qui répond au problème posé du maintien de la spécification en RON avec une teneur limitée en aromatiques.Table 5 above shows that the process of Example 2 according to the invention makes it possible to produce a paraffinic cut without aromatics (stream 3) and a cut rich in cyclic molecules (stream 7), both of RON compatible with a use in the gasoline pool. It is therefore possible to recombine the two streams (stream 3 + stream 7) to obtain a depleted cut in aromatics with respect to the feed (stream 1) and RON much higher than 80 which answers the problem of maintaining the specification. in RON with a limited content of aromatics.

Claims (7)

  1. Process for the production of a RON isomerate that is at least equal to 80 and for co-production of a naphthenic fraction that for the most part consists of methylcyclohexane and optionally toluene, starting from a fresh C7 hydrocarbon feedstock containing paraffins, naphthenes and aromatic compounds in any proportion, whereby said process employs at least one distillation column, at least one isomerization unit, and at least one unit for separating normal paraffins and cyclic molecules, in particular methylcyclohexane, characterized in that the isomerate that is produced contains less than 1 % by weight of aromatic compounds and preferably less than 0.5% by weight of aromatic compounds, and in that the fresh feedstock is introduced into a distillation column from which are extracted a) a top flow that provides the isomerate that is produced, b) a lateral flow that feeds in a mixture an isomerization unit, and c) a bottom flow that is introduced into a unit for separating normal paraffins, on the one hand, and cyclic molecules, on the other hand, in particular methylcyclohexane, whereby normal paraffins are introduced in a mixture with the lateral flow into an isomerization unit and the naphthenic fraction is produced with a purity level that is at least equal to 90% by mass.
  2. Process according to claim 1, wherein one of the isomerization units is fed by the lateral draw-off that is obtained from said distillation column, whereby after stabilization, the effluent of the isomerization is sent back into the distillation column at a level located above the level of the lateral draw-off.
  3. Process according to any of claims 1 to 2, wherein the top flow of the distillation column is sent into a unit for separating normal paraffins and mono-branched paraffins, on the one hand, and di-branched paraffins and tri-branched paraffins, on the other hand, whereby the normal paraffins and mono-branched paraffins are reintroduced into the isomerization unit, and the di-branched paraffins and tri-branched paraffins constitute the isomerate.
  4. Process according to any of claims 1 to 3, wherein the fresh feedstock is introduced upstream from the distillation column into a unit for hydrogenating toluene that makes it possible to transform the latter into methylcyclohexane.
  5. Process according to any of claims 1 to 4, wherein the distillation column is of the type: column with an internal wall.
  6. Process according to any of claims 1 to 5, wherein the separation of the normal paraffins, on the one hand, and cyclic molecules, on the other hand, is carried out by an adsorption process.
  7. Process according to any of claims 1 to 5, wherein the separation of normal paraffins, on the one hand, and cyclic molecules, on the other hand, is carried out by a membrane process.
EP05291856A 2004-09-22 2005-09-07 Process of isomerisation of a C7 cut with coproduction of a cyclic cut comprising mainly methyl cyclohexane Expired - Fee Related EP1640436B1 (en)

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FR0409998A FR2875507B1 (en) 2004-09-22 2004-09-22 IMPROVED ISOMERIZATION METHOD OF A C7 CUT WITH COPRODUCTION OF A CUT RICH IN CYCLIC MOLECULES

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US6938772B2 (en) * 2002-06-04 2005-09-06 Rehrig Pacific Company Portable storage container
US7334683B2 (en) * 2004-04-12 2008-02-26 Rehrig Pacific Company Portable storage container
US7249675B2 (en) * 2004-05-25 2007-07-31 Rehrig Pacific Company Portable storage container
US7823728B2 (en) * 2005-03-04 2010-11-02 Rehrig Pacific Company Storage container with support structure for multiple levels of nesting
US7581641B2 (en) * 2005-04-18 2009-09-01 Rehrig Pacific Company Portable storage container
US7484621B2 (en) * 2005-09-09 2009-02-03 Rehrig Pacific Company Tray
WO2007059873A1 (en) * 2005-11-22 2007-05-31 Haldor Topsøe A/S C7 isomerisation with reactive distillation
US7777089B2 (en) * 2006-12-06 2010-08-17 Haldor Topsøe A/S Hydrocarbon separation
US8003842B2 (en) * 2006-12-06 2011-08-23 Haldor Topsøe A/S Hydrocarbon separation
US8808534B2 (en) 2011-07-27 2014-08-19 Saudi Arabian Oil Company Process development by parallel operation of paraffin isomerization unit with reformer
FR3034764B1 (en) * 2015-04-13 2017-04-28 Ifp Energies Now PROCESS FOR ISOMERIZING A C7 TO C11 HYDROCARBON LOAD
US11820552B2 (en) 2019-08-26 2023-11-21 Rehrig Pacific Company Containers for oil bottles or the like

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GB9013566D0 (en) * 1990-06-18 1990-08-08 Shell Int Research Process for producing gasoline components
FR2771419B1 (en) * 1997-11-25 1999-12-31 Inst Francais Du Petrole HIGH-INDEX OCTANE ESSENCES AND THEIR PRODUCTION BY A PROCESS COMBINING HYDRO-ISOMERIZATION AND SEPARATION
FR2813311B1 (en) * 2000-08-25 2002-11-29 Inst Francais Du Petrole PROCESS ASSOCIATING HYDROISOMERIZATION AND SEPARATION WITH A MIXED STRUCTURED ZEOLITHIC ABSORBENT FOR THE PRODUCTION OF HIGH OCTANE INDEX ESSENCES
FR2857371B1 (en) * 2003-07-11 2007-08-24 Inst Francais Du Petrole IMPROVED ISOMERIZATION METHOD OF A C7 CUT WITH OPENING OF THE NAPHTENIC CYCLES

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DE602005002597T2 (en) 2008-01-31
US20060065576A1 (en) 2006-03-30
FR2875507B1 (en) 2008-10-31
FR2875507A1 (en) 2006-03-24
US7481916B2 (en) 2009-01-27
EP1640436A1 (en) 2006-03-29

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