WO2013067620A1 - Procédé d'oligomérisation de l'éthylène utilisant un solvant aromatique halogéné avec un aluminoxane/des composés organoborés comme activateurs - Google Patents

Procédé d'oligomérisation de l'éthylène utilisant un solvant aromatique halogéné avec un aluminoxane/des composés organoborés comme activateurs Download PDF

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WO2013067620A1
WO2013067620A1 PCT/CA2012/000983 CA2012000983W WO2013067620A1 WO 2013067620 A1 WO2013067620 A1 WO 2013067620A1 CA 2012000983 W CA2012000983 W CA 2012000983W WO 2013067620 A1 WO2013067620 A1 WO 2013067620A1
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reactor
ethylene
oligomerization
catalyst
reaction
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PCT/CA2012/000983
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English (en)
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Stephen John Brown
Charles Ashton Garret Carter
P. Scott Chisholm
Peter Zoricak
Oleksiy Golovchenko
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Nova Chemicals (International) S.A.
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Publication of WO2013067620A1 publication Critical patent/WO2013067620A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C2/00—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms
    • C07C2/02—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms by addition between unsaturated hydrocarbons
    • C07C2/04—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms by addition between unsaturated hydrocarbons by oligomerisation of well-defined unsaturated hydrocarbons without ring formation
    • C07C2/06—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms by addition between unsaturated hydrocarbons by oligomerisation of well-defined unsaturated hydrocarbons without ring formation of alkenes, i.e. acyclic hydrocarbons having only one carbon-to-carbon double bond
    • C07C2/08—Catalytic processes
    • C07C2/26—Catalytic processes with hydrides or organic compounds
    • C07C2/36—Catalytic processes with hydrides or organic compounds as phosphines, arsines, stilbines or bismuthines
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C2531/00—Catalysts comprising hydrides, coordination complexes or organic compounds
    • C07C2531/02—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides
    • C07C2531/12—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides containing organo-metallic compounds or metal hydrides
    • C07C2531/14—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides containing organo-metallic compounds or metal hydrides of aluminium or boron
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C2531/00—Catalysts comprising hydrides, coordination complexes or organic compounds
    • C07C2531/16—Catalysts comprising hydrides, coordination complexes or organic compounds containing coordination complexes
    • C07C2531/24—Phosphines

Definitions

  • This invention relates to a novel activation system for the catalytic
  • Alpha olefins are commercially produced by the oligomerization of ethylene in the presence of a simple alkyl aluminum catalyst (in the so called “chain growth” process) or alternatively, in the presence of an organometallic nickel catalyst (in the so called Shell Higher Olefins, or "SHOP" process). Both of these processes typically produce a crude oligomer product having a broad distribution of alpha olefins with an even number of carbon atoms (i.e. butene-1 , hexene-1 , octene-1 , etc.). The various alpha olefins in the crude oligomer product are then typically separated in a series of distillation columns.
  • Butene-1 is generally the least valuable of these olefins as it is also produced in large quantities as a by-product in various cracking and refining processes. Hexene-1 and octene-1 often command comparatively high prices because these olefins are in high demand as comonomers for linear low density polyethylene (LLDPE).
  • LLDPE linear low density polyethylene
  • WO04/056478 and WO 04/056479 (now US 2006/0229480 and US 2006/0173226).
  • the disphosphine/tetraphenyl ligands disclosed by Blann et al. generally do not contain polar substituents in ortho positions.
  • the "tetraphenyl" diphosphine ligands claimed in the '480 application must not have ortho substituents (of any kind) on all four of the phenyl groups and the "tetraphenyl" diphosphine ligands claimed in '226 are characterized by having a polar substituent in a meta or para position.
  • chromium/diphosphine catalysts generally require an activator or catalyst in order to achieve meaningful rates of oligomerization.
  • Aluminoxane are well known activators for this catalyst system.
  • Methylaluminoxane (“MAO”) - which is made from trimethyl aluminum (TMA) - is generally preferred in terms of activity but suffers from a cost disadvantage.
  • organoboron activators as an alternative to MAO is also known.
  • Such activators may also be referred to as "stoichiometric" activators because they can be used in essentially equimolar amounts to the chromium catalyst (i.e.
  • organoborates are typically reported to be used in combination with an aluminum alkyl and the reactivity of the catalyst system has been reported to be dependent upon the amount of aluminum alkyl (McGuinness et al., Organomettallics, 2007, 26, 1 108-1 111).
  • the process of this invention reduces the difficulties associated with starting up the oligomerization reaction and also allows the use of an organboron co-activator.
  • the organoboron activator allows for cost reduction (as it allows the amount of oligomer product being produced to be increased without further increasing the amount of the expensive MAO co-catalyst).
  • the present invention provides a process for the
  • a ligand defined by the formula (R 1 )(R 2 )-P -bridge-P 2 (R 3 )(R 4 ) wherein R , R 2 ,R 3 and R 4 are independently selected from the group consisting of hydrocarbyl and heterohydrocarbyl and the bridge is a divalent moiety that is bonded to both phosphorus atoms;
  • start up step is conducted in a halogenated aromatic solvent; and B) a second step wherein an organoboron activator is added to said process, wherein said second step occurs subsequent to said start up step.
  • steady state is meant to convey its conventional meaning, namely that the process is not proceeding in an erratic/unsteady manner.
  • Examples of non- steady state conditions include rapid temperature excursions (e.g. A strong exotherm caused by a rapid initiator) and rapid changes in ethylene flow (in processes where ethylene is fed on demand, in response to changes in reactor pressure).
  • the catalyst system used in the process of the present invention must contain four essential components, namely:
  • diphosphine ligand used in the oligomerization process of this invention is defined by the formula (R 1 )(R 2 )-P 1 -bridge-P 2 (R 3 )(R 4 ) wherein R 1 , R 2 ,R 3 and R are independently selected from the group consisting of hydrocarbyl and heterohydrocarbyl and the bridge is a divalent moiety that is bonded to both
  • hydrocarbyl as used herein is intended to convey its conventional meaning - i.e. a moiety that contains only carbon and hydrogen atoms.
  • hydrocarbyl moiety may be a straight chain; it may be branched (and it will be recognized by those skilled in the art that branched groups are sometimes referred to as "substituted”); it may be saturated or contain unsaturation and it may be cyclic.
  • Preferred hydrocarbyl groups contain from 1 to 20 carbon atoms.
  • Aromatic groups - especially phenyl groups - are especially preferred.
  • the phenyl may be unsubstituted (i.e. a simple C 6 H 5 moiety) or contain substituents, particularly at an ortho (or "o") position.
  • heterohydrocarbyl as used herein is intended to convey its conventional meaning - more particularly, a moiety that contains carbon, hydrogen and at least one heteroatom (such as O, N, R and S).
  • the heterohydrocarbyl groups may be straight chain, branched or cyclic structures. They may be saturated or contain unsaturation.
  • Preferred heterohydrocarbyl groups contain a total of from 2 to 20 carbon + heteroatoms (for clarity, a hypothetical group that contains 2 carbon atoms and one nitrogen atom has a total of 3 carbon + heteroatoms).
  • each of R 1 , R 2 , R 3 and R 4 is a phenyl group (with an optional substituent in an ortho position on one or more of the phenyl groups).
  • Highly preferred ligands are those in which R 1 to R 4 are independently selected from the group consisting of phenyl, o-methylphenyl (i.e. ortho-methylphenyl), o-ethylphenyl, o-isopropylphenyl and o-fluorophenyl. It is especially preferred that none of R 1 to R 4 contains a polar substituent in an ortho position.
  • the resulting ligands are useful for the selective tetramerization of ethylene to octene-1 with some co-product hexene also being produced.
  • the term "bridge” as used herein with respect to the ligand refers to a divalent moiety that is bonded to both of the phosphorus atoms in the ligand - in other words, the "bridge” forms a link between P and P 2 .
  • Suitable groups for the bridge include hydrocarbyl and an inorganic moiety selected from the group consisting of N(CH 3 )-N(CH 3 )-, -B(R 6 )-, -Si(R 6 ) 2 -, -P(R 6 )- or -N(R 6 )- where R 6 is selected from the group consisting of hydrogen, hydrocarbyl and halogen.
  • the bridge is -N(R 5 )- wherein R 5 is selected from the group consisting of hydrogen, alkyl, substituted alkyl, aryl, substituted aryl, aryloxy, substituted aryloxy, halogen, alkoxycarbonyl, carbonyloxy, alkoxy, aminocarbonyl, carbonylamino, dialkylamino, silyl groups or derivatives thereof and an aryl group substituted with any of these substituents.
  • a highly preferred bridge is amino isopropyl (i.e. when R 5 is isopropyl).
  • two different types of ligands are used to alter the relative amounts of hexene and octene being produced.
  • the use of a ligand that produces predominantly hexene may be used in combination with a ligand that produces predominantly octene.
  • chromium sources include chromium trichloride; chromium (III) 2-ethylhexanoate; chromium (III) acetylacetonate and chromium carbonyl complexes such as chromium hexacarbonyl. It is preferred to use very high purity chromium compounds as these should generally be expected to minimize undesirable side reactions. For example, chromium acetylacetonate having a purity of higher than 99% is commercially available (or may be readily produced from 97% purity material - using recrystallization techniques that are well known to those skilled in the art).
  • Catalyst systems comprising the above described ligands and a source of chromium are well known for the oligomerization of ethylene.
  • concentrations that are typically disclosed in the relevant prior art are generally from 20 to 400 micromolar.
  • the present invention preferably uses a lower chromium
  • concentration of from 0.5 to 8 micromolar especially from 0.5 to 5 micromolar (i.e. from 0.5 to 8 x 10 "6 gram moles per litre).
  • Aluminoxanes are well known, commercially available items of commerce. They may be prepared by the controlled addition of water to an alkyl aluminum compound such as TMA or TIBAL. Non-hydrolytic techniques to prepare aluminoxanes are also reported in the literature and are believed to be used by the AKZO Nobel Company to produce certain commercial products.
  • MAO methylaluminoxane
  • TMA methylaluminoxane
  • TIBAL a higher alkyl aluminum
  • Those MAO's are generally referred to as “modified MAO's” and they are suitable for use in this invention.
  • commercially available MAO typically contains some "residual” or “free” TMA that is associated with the MAO. "Free TMA” typically is present in amounts of from 10 to 40 mole % of the total aluminum contained in the MAO (+ TMA) and this is a preferred level for use in this invention.
  • TMA and MAO are expensive materials.
  • TEAL triethylaluminum
  • the amount of TEAL is sufficient to provide from about 10 to 70% of the total aluminum that is added to the process on a molar basis - i.e.: (the moles of aluminum contained in TEAL) ⁇ (the moles of aluminum contained in TEAL + TMA + MAO) x 100% is from 0 to 70 %.
  • the amount of aluminoxane, TMA and TEAL is preferably sufficient to provide a total AI:Cr molar ratio of from 50: 1 to 1000: 1 , especially from 100: 1 to 500: 1 .
  • the aluminum concentration in the reactor is at least 2 millimolar (2000 micromolar) because lower levels of aluminum may not be sufficient to
  • each R 7 is independently selected from the group consisting of phenyl radicals which are unsubstituted or substituted with from 3 to 5 substituents selected from the group consisting of a fluorine atom, a C alkyl or alkoxy radical which is unsubstituted or substituted by a fluorine atom; and a silyl radical of the formula -Si-(R ) 3 ; wherein each R 9 is independently selected from the group consisting of a hydrogen atom and a CM alkyl radical; and
  • R 7 is a pentafluorophenyl radical
  • Z is a nitrogen atom
  • R 8 is a Ci -8 alkyl radical or R 8 taken together with the nitrogen atom forms an anilinium radical which is substituted by two Ci -4 alkyl radicals.
  • organobron activators examples include:
  • triphenylphosphonium tetra(phenyl)boron triphenylphosphonium tetra(phenyl)boron
  • triphenylmethylium tetrakispentafluorophenyl borate triphenylmethylium tetrakispentafluorophenyl borate
  • ionic activators include:
  • triphenylmethylium tetrakispentafluorophenyl borate triphenylmethylium tetrakispentafluorophenyl borate
  • Chlorinated or fluorinated solvents are preferred. It is particularly preferred to use a chlorobenzene solvent. Examples include monochlorobenzene, dichlorobenzene, trichlorobenzene, and mixtures thereof (It will be appreciated by those skilled in the art that several isomers of dichlorobenzene and trichlorobenzene exist - depending upon the placement of the chlorine substituent. The present invention is not restricted to the use of any particular such isomer).
  • the process of the present invention is preferably conducted in a continuously stirred tank reactor (CSTR).
  • CSTR continuously stirred tank reactor
  • the process may be batch, semi-batch, or continuous.
  • a batch process requires that the reactor is not liquid full at the start of the reaction (to allow for the volume of product that is produced).
  • the reactor is preferably filled to a level of from about 10 1 25% by volume with halogenated aromatic solvent before the reaction is initiated.
  • the chromium and ligand may be present in any molar ratio which produces oligomer, preferably between 100:1 and 1 :100, and most preferably from 10:1 to 1 :10, particularly 3:1 to 1 :3. Generally the amounts of (i) and (ii) are approximately equal, i.e. a ratio of between 1.5:1 and 1 :1.5.
  • the catalyst components may be mixed together in the oligomerization reactor, or - alternatively - some or all of the catalyst components may be mixed together outside of the oligomerization reactor. Suitable methods of catalyst synthesis are illustrated in the examples.
  • Ethylene is preferably fed to the reactor on demand.
  • the ethylene may be fed as a gas or as solution. Again, halogenated aromatic solvent may be used to add the ethylene but this is not necessary.
  • halogenated aromatic solvent If additional halogenated aromatic solvent is not added to the reactor during a continuous process, the concentration of such solvent will decrease with time (as solvent and product are removed from the reactor). It is generally desirable to maintain a concentration of halogenated solvent of at least 5 volume %.
  • a variety of methods are known to purify solvents used in the oligomerization process including use of molecular sieves (3A), adsorbent alumina and supported de-oxo copper catalyst.
  • 3A molecular sieves
  • adsorbent alumina adsorbent alumina
  • supported de-oxo copper catalyst a variety of methods are known to purify solvents used in the oligomerization process.
  • the process solvent is first contacted with molecular sieves, followed by adsorbent alumina, then followed by supported de-oxo copper catalyst and finally followed by molecular sieves.
  • the solvent is first contacted with molecular sieves, followed by adsorbent alumina and finally followed by molecular sieves.
  • the solvent is contacted with adsorbent alumina.
  • the oligomerization is typically carried out under conditions that substantially exclude oxygen, water, and other materials that act as catalyst poisons.
  • the reactor is preferably purged with a nonreactive gas (such as nitrogen or argon) prior to the introduction of catalyst.
  • a purge with a solution of MAO and/or aluminum alkyl may also be employed to lower the initial level of catalyst poisons.
  • the use of hydrogen is especially preferred because it has been observed to reduce the amount of polymer that is formed.
  • the most preferred catalysts of this invention predominantly produce octene with some hexene (as shown in the examples) but smaller quantities of butene and C10+ olefins are also produced.
  • the crude product stream may be separated into various fractions using, for example, a conventional distillation system. It is within the scope of this invention to recycle the "whole" oligomer product or some fraction(s) thereof to the reaction for use as an oligomerization diluent. For example, by recycling a butene rich stream it might be possible to lower the refrigeration load in distillation. Alternatively, the Ci 0 + fraction might be preferentially recycled to improve the solubility of one or more components of the catalyst system.
  • Techniques for varying the distribution of products from the oligomerization reactions include controlling process conditions (e.g. concentration of components (i)- (iii), reaction temperature, pressure, residence time) and properly selecting the design of the process and are well known to those skilled in the art.
  • a catalyst that produces ethylene homopolymer is deliberately added to the reactor in an amount sufficient to convert from 1 to 5 weight% of the ethylene feed to an ethylene homopolymer.
  • This catalyst is preferably supported. The purpose is to facilitate the removal of by-product polyethylene.
  • the ethylene feedstock for the oligomerization may be substantially pure or may contain other olefinic impurities and/or ethane.
  • One embodiment of the process of the invention comprises the oligomerization of ethylene-containing waste streams from other chemical processes or a crude ethylene/ethane mixture from an ethane to ethylene cracker.
  • the feedstock is preferably treated to remove catalyst poisons (such as oxygen, water and polar species) using techniques that are well known to those skilled in the art.
  • catalyst poisons such as oxygen, water and polar species
  • the technology used to treat feedstocks for polymerizations is suitable for use in the present invention and includes the molecular sieves, alumina and de-oxo catalysts described above for analogous treatment of the process solvent.
  • oligomerization reactors for selective oligomerization are provided first, followed by a detailed description of preferred reactor designs.
  • oligomerization reactor can generally be performed under a range of process conditions that are readily apparent to those skilled in the art. Evaporative cooling from one or more monomers or inert volatile liquids is but one (prior art) method that can be employed to effect the removal of heat from the reaction.
  • the reactions may be performed in the known types of reactors, such as a plug-flow reactor, or a continuously stirred tank reactor (CSTR), or a loop reactor, or combinations thereof.
  • CSTR continuously stirred tank reactor
  • a wide range of methods for effecting product, reactant, and catalyst separation and/or purification are known to those skilled in the art and may be employed: distillation, filtration, liquid-liquid separation, slurry settling, extraction, etc.
  • One or more of these methods may be performed separately from the oligomerization reaction or it may be advantageous to integrate at least some with the reaction; a non- limiting example of this would be a process employing catalytic (or reactive) distillation.
  • Also advantageous may be a process which includes more than one reactor, a catalyst kill system between reactors or after the final reactor, or an integrated
  • reactor/separator/purifier While all catalyst components, reactants, inerts, and products could be employed in the present invention on a once-through basis, it is often economically advantageous to recycle one or more of these materials; in the case of the catalyst system, this might require reconstituting one or more of the catalysts components to achieve the active catalyst system.
  • the present invention also encompasses other reactor designs for selective oligomerizations.
  • a non adiabatic reactor system may be used.
  • the term “non adiabatic” means that heat is added to and/or removed from the oligomerization reactor.
  • the term “reactor system” means that one or more reactors are employed (and the term “non adiabatic reactor system” means that at least one of the reactors is equipped with a heat exchanger that allows heat to be added to or removed from it).
  • One design relates to a CSTR with an external heat exchanger.
  • a second design relates to a tubular plug flow equipped with multiple feed ports for ethylene along the length of the reactor.
  • a third design relates to a combination of a CSTR followed by a tubular reactor.
  • a fourth design provides a loop reactor.
  • a fifth design provides a reactor having an internal cooling system (such as a draft tube reactor).
  • oligomerization process is a tube that exits the reactor and flows through the shell for heat exchange, then reenters the reactor with cooled (or heated) process fluid.
  • process fluid a portion of the hot reactor contents or "process fluid” will flow from the reactor to the external heat exchanger, through a tube. The exterior of the tube comes into contact with cold fluid on the shell side of the exchanger, thus cooling the process fluid. The cooled process fluid is then returned to the reactor.
  • a heat exchanger is located between two CSTRs.
  • the product from the first oligomerization reactor leaves that reactor through an exit tube.
  • the oligomerization products in this exit tube are then directed through a heat exchanger. After being cooled by the heat exchanger, the
  • oligomerization products are then directed into a second CSTR. Additional ethylene (and, optionally, catalyst) is added to the second CSTR and further oligomerization takes place.
  • the amount of heat generated by the oligomerization reaction is generally proportional to the amount of ethylene being oligomerized.
  • a high rate of coolant flow is required in the shell side of the exchanger.
  • the rate of oligomerization is generally proportional to the amount of ethylene and catalyst that are fed to the CSTR.
  • the ethylene is first contacted with solvent in a mixing vessel that is external to the CSTR.
  • this mixing vessel is referred to herein as a "solution absorber".
  • the solution absorber is preferably equipped with a heat exchanger to remove the heat of absorbtion - i.e. heat is generated when the ethylene dissolves in the solvent and this heat exchanger removes the heat of solution.
  • the solution absorber may be a CSTR, or alternatively, a simple plug flow tube.
  • the heat exchanger on the solution absorber is used to provide cooled feed.
  • the heat exchanger may be used to chill the feed to below ambient conditions - this is desirable to maximize reactor throughput.
  • this heat exchanger is provided that allows the feed stream to be heated.
  • This heat exchanger may be located in direct contact with the solution absorber or - alternatively, this heat exchanger may be located between the solution absorber and the oligomerization reactor. In general, this heat exchanger will be used during non-steady state conditions (such as are encountered at start up or during a reactor upset) to quickly provide heat to the reactor.
  • the CSTR is preferably operated in continuous flow mode - i.e. feed is continuously provided to the CSTR and product is continuously withdrawn.
  • the CSTR described above may be used to provide the high degree of temperature control that we have observed to be associated with a low degree of polymer formation.
  • the CSTR is equipped with one or more of the mixing elements described in USP 6,319,996 (Burke et al.).
  • Burke et al. disclose the use of a tube which has a diameter that is approximately equal to the diameter of the agitator of the CSTR. This tube extends along the length of the agitator shaft, thereby forming a mixing element that is often referred to as a "draft tube” by those skilled in the art.
  • the reactor used in this invention may also employ the mixing helix disclosed by Burke et al. (which helix is located within the draft tube and forms a type of auger or Archimedes screw within the draft tube).
  • stationary, internal elements to divide the CSTR into one or more zones
  • two impellers are vertically displaced along the length of the agitation shaft i.e. one in the top part of the reactor and another in the bottom.
  • An internal "ring” or “doughnut” is used to divide the CSTR into a top reaction zone and a bottom reaction zone.
  • the ring is attached to the diameter of the CSTR and extends inwardly towards the agitation shaft to provide a barrier between the top and bottom reaction zones.
  • a hole in the center of the ring allows the agitation shaft to rotate freely and provides a pathway for fluid flow between the two reactions zones.
  • the use of such rings or doughnuts to divide a CSTR into different zones is well known to those skilled in the art of reactor design.
  • two or more separate agitators with separate shafts and separate drives may be employed.
  • a small impeller might be operated at high velocity/high shear rate to disperse the catalyst and/or ethylene as it enters the reactor and a separate (larger) impeller with a draft tube could be used to provide circulation within the reactor.
  • Tubular/plug flow reactors are well known to those skilled in the art. In general, such reactors comprise one or more tubes with a length/diameter ratio of from 10/1 to 000/1. Such reactors are not equipped with active/powered agitators but may include a static mixer. Examples of static mixers include those manufactured and sold by Koch-Glitsch Inc. and Sulzer-Chemtech.
  • the tubular reactor is a so called "heat-exchange reactor” which is generally configured as a tube and shell heat exchanger.
  • the oligomerization reaction occurs inside the tube(s) of this reactor.
  • the shell side provides a heat exchange fluid (for the purposes described above, namely to heat the reaction during start up and/or to cool the reaction during steady state operations).
  • the tubes are bent so as to form a type of static mixer for the fluid passing through the shell side.
  • This type of heat exchanger is known to those skilled in the art and is available (for example) from Sulzer-Chemtech under the trade name SMR.
  • the Reynolds number of the reaction fluid that flows through the tube (or tubes) of the tubular reactor is from 2,000 to 10,000,000. Reynolds number is a dimensionless number that is readily calculated using the following formula:
  • V is the mean fluid velocity (SI units: m/s);
  • L is a characteristic linear dimension (e.g. internal diameter of tube);
  • p is the density of the fluid (kg/m 3 ).
  • a plurality of heat exchange reactors are connected in series.
  • the process flow that exits the first reactor enters the second reactor.
  • Additional ethylene is added to the process flow from the first reactor but additional catalyst is preferably not added.
  • a CSTR is connected in series to a tubular reactor.
  • This dual reactor system comprises a CSTR operated in adiabatic mode, followed by a tubular reactor having an external heat exchanger - in this embodiment the amount of ethylene that is consumed (i.e. converted to oligomer) in the CSTR is less than 50 weight % of the total ethylene that is consumed in the reactors.
  • a CSTR that is equipped with an external heat exchanger is connected to a downstream tubular reactor that is operated in adiabatic mode. In this embodiment, the amount of ethylene that is converted/consumed in the CSTR is in excess of 80 weight % of the ethylene that is consumed in the reactor.
  • the tubular reactor may also have several different ports which allow the addition of catalyst killer/deactivator along the length of the reactor. In this manner, some flexibility is provided to allow the reaction to be terminated before the product exits from the reactor.
  • Loop reactors are well known and are widely described in the literature.
  • One such design is disclosed in USP 4,121 ,029 (Irvin et al.).
  • the loop reactor disclosed by Irvin et al. contains a "wash column” that is connected to the upper leg of the loop reactor and is used for the collection of polymer.
  • a similar "wash column” is contemplated for use in the present invention to collect by-product polymer (and/or supported catalyst).
  • a hydrocyclone at the top end of the wash column may be used to facilitate polymer separation.
  • a fifth reactor design for use in the present invention is another type of heat exchange reactor in which the process side (i.e. where the oligomerization occurs) is the "shell side" of the exchanger.
  • This reactor design is a so called “draft tube” reactor of the type reported to be suitable for the polymerization of butyl rubber.
  • This type of reactor is characterized by having an impeller located near the bottom of the reactor, with little or no agitator shaft extending into the reactor. The impeller is encircled with a type of "draft tube” that extends upwards through the center of the reactor.
  • the draft tube is open at the bottom (to allow the reactor contents to be drained into the tube, for upward flow) and at the top - where the reactor contents are discharged from the tube.
  • a heat exchanger tube bundle is contained within the reactor and is arranged such that the tubes run parallel to the draft tube and are generally arranged in a concentric pattern around the draft tube. Coolant flows through the tubes to remove the heat of the reaction.
  • Monomer is preferably added by one or more feed ports that are located on the perimeter of the reactor (especially near the bottom of the reactor) and oligomerization product is withdrawn through at least one product exit port (preferably located near the top of the reactor).
  • Catalyst is preferably added through a separate feed line that is not located close to any of the monomer feed ports(s) or product exit port(s).
  • Draft tube reactors are well known and are described in more detail in USP 4,007,016 (Weber) and USP 2,474,592 (Palmer) and the references therein.
  • Figure 2 of USP 2,474,592 illustrates the use of a fluid flushing system to flush the agitator shaft in the vicinity of the agitator shaft seal.
  • a fluid chamber through the agitator shaft seal is connected to a source of flushing fluid (located outside of the reactor) and the channel terminates in the area where the agitator shaft enters the reactor.
  • flushing fluid is pumped through the channel to flush the base of the agitator and thereby reduce the amount of polymer build up at this location.
  • Another known technique to reduce the level of fouling in a chemical reactor is to coat the reactor walls and/or internals and/or agitators with a low fouling material such as glass or polytetraflouroethylene (PTFE).
  • a low fouling material such as glass or polytetraflouroethylene (PTFE).
  • PTFE polytetraflouroethylene
  • temperature (together with reactor flow rates and the known enthalpy of reaction) may be used to monitor ethylene conversion rates.
  • the amount of catalyst may be increased to increase the ethylene conversion (or decreased to decrease ethylene conversion) within desired ranges.
  • basic process control may be derived from simple measurements of temperature, pressure and flow rates using conventional thermocouples, pressure meters and flow meters.
  • Advanced process control (for example, for the purpose of monitoring product selectivity or for the purpose of monitoring process fouling factors) may be undertaken by monitoring additional process parameters with more advanced instrumentation.
  • Known/existing instrumentation include in-line/on-line instruments such as NIR infrared, Fourier Transform Infrared (FTIR), Raman, mid-infrared, ultra violet (UV) spectrometry, gas chromatography (GC) analyzer, refractive index, on-line densitometer or viscometer.
  • FTIR Fourier Transform Infrared
  • GC gas chromatography
  • refractive index on-line densitometer or viscometer.
  • the measurement may be used to monitor and control the reaction to achieve the targeted stream properties including but not limited to concentration, viscosity, temperature, pressure, flows, flow ratios, density, chemical composition, phase and phase transition, degree of reaction, polymer content, selectivity.
  • the control method may include the use of the measurement to calculate a new control set point.
  • the control of the process will include the use of any process control algorithms, which include, but are not limited to the use of PID, neural networks, feedback loop control, forward loop control and adaptive control.
  • the oligomerization catalyst is preferably deactivated immediately downstream of the reactor as the product exits the reaction vessel. This is to prevent polymer formation and potential build up downstream of the reactor and to prevent isomerisation of the 1 -olefin product to the undesired internal olefins. It is generally preferred to flash and recover unreacted ethylene before deactivation. However, the option of deactivating the reactor contents prior to flashing and recovering ethylene is also acceptable.
  • the flashing of ethylene is endothermic and may be used as a cooling source. In one embodiment, the cooling provided by ethylene flashing is used to chill a feedstream to the reactor.
  • polar compounds such as water, alcohols and carboxylic acids
  • deactivate the catalyst many polar compounds (such as water, alcohols and carboxylic acids) will deactivate the catalyst.
  • alcohols and/or carboxylic acids is preferred - and combinations of both are contemplated.
  • the quantity employed to deactivate the catalyst is sufficient to provide deactivator to metal (from activator) mole ratio between about 0.1 to about 4.
  • the deactivator may be added to the oligomerization product stream before or after the volatile unreacted reagents/diluents and product components are separated. In the event of a runaway reaction (e.g. rapid temperature rise) the deactivator can be immediately fed to the oligomerization reactor to terminate the reaction.
  • Polymer removal (and, optionally, catalyst removal) preferably follows catalyst deactivation.
  • Two “types” of polymer may exist, namely polymer that is dissolved in the process solvent and non-dissolved polymer that is present as a solid or "slurry".
  • Solid/non-dissolved polymer may be separated using one or more of the following types of equipment: centrifuge; cyclone (or hydrocyclone), a decanter equipped with a skimmer or a filter.
  • Preferred equipment include so called “self cleaning filters” sold under the name V-auto strainers, self cleaning screens such as those sold by Johnson Screens Inc. of New Brighton, Minnesota and centrifuges such as those sold by Alfa Laval Inc. of Richmond, VA (including those sold under the trade name Sharpies).
  • Soluble polymer may be separated from the final product by two distinct operations. Firstly, low molecular weight polymer that remains soluble in the heaviest product fraction (C20+) may be left in that fraction. This fraction will be recovered as "bottoms” from the distillation operations (described below). This solution may be used as a fuel for a power generation system.
  • An alternative polymer separation comprises polymer precipitation caused by the removal of the solvent from the solution, followed by recovery of the precipitated polymer using a conventional extruder.
  • the residual catalyst is treated with an additive that causes some or all of the catalyst to precipitate.
  • the precipitated catalyst is preferably removed from the product at the same time as by-product polymer is removed (and using the same equipment). Many of the catalyst deactivators listed above will also cause catalyst precipitation.
  • a solid sorbent such as clay, silica or alumina is added to the deactivation operation to facilitate removal of the deactivated catalyst by filtration or centrifugation.
  • Reactor fouling (caused by deposition of polymer and/or catalyst residue) can, if severe enough, cause the process to be shut down for cleaning.
  • the deposits may be removed by known means, especially the use of high pressure water jets or the use of a hot solvent flush.
  • the use of a halogenated aromatic solvent for solvent flushing is generally preferred because they are good solvents for polyethylene.
  • the use of the heat exchanger that provides heat to the present process may also be used during cleaning operations to heat the cleaning solvent.
  • the oligomerization product produced from this invention is added to a product stream from another alpha olefins manufacturing process for separation into different alpha olefins.
  • "conventional alpha olefin plants” (wherein the term includes i) those processes which produce alpha olefins by a chain growth process using an aluminum alkyl catalyst, ii) the aforementioned "SHOP" process and iii) the production of olefins from synthesis gas using the so called Lurgi process) have a series of distillation columns to separate the "crude alpha product" (i.e.
  • the mixed hexene-octene product which is preferably produced in accordance with the present invention is highly suitable for addition/mixing with a crude alpha olefin product from an existing alpha olefin plant (or a "cut" or fraction of the product from such a plant) because the mixed hexene- octene product produced in accordance with the present invention can have very low levels of internal olefins.
  • the hexene-octene product of the present invention can be readily separated in the existing distillation columns of alpha olefin plants (without causing the large burden on the operation of these distillation columns which would otherwise exist if the present hexene-octene product stream contained large quantities of internal olefins).
  • the term "liquid product” is meant to refer to the oligomers produced by the process of the present invention which have from 4 to (about) 20 carbon atoms.
  • the distillation operation for the oligomerization product is integrated with the distillation system of a solution polymerization plant.
  • the liquid product from the oligomerization process of the present invention preferably consists of from 20 to 80 weight % octenes (especially from 35 to 75 weight %) octenes and from 5 to 50 weight % (especially from 20 to 40 weight %) hexenes (where all of the weight % are calculated on the basis of the liquid product by 100%.
  • the preferred oligomerization process of this invention is also characterized by producing very low levels of internal olefins (i.e. low levels of hexene-2, hexene-3, octene-2, octene-3 etc.), with preferred levels of less than 10 weight % (especially less than 5 weight %) of the hexenes and octenes being internal olefins.
  • PE polyethylene
  • This section illustrates the synthesis of a preferred but non-limiting ligand for use in the present invention.
  • Reaction solvents were purified prior to use (e.g. by distillation) and stored over activated 4 A sieves. Diethylamine, triethylamine and isopropylamine were purchased from Aldrich and dried over 4 A molecular sieves prior to use. 1-Bromo-2-fluoro- benzene, phosphorus trichloride (PCI 3 ), hydrogen chloride gas and n-butyllithium were purchased from Aldrich and used as is. The methylalumoxane (MAO), 10 weight % Al in toluene, was purchased from Akzo and used as is.
  • Diethylamine, triethylamine and isopropylamine were purchased from Aldrich and dried over 4 A molecular sieves prior to use.
  • 1-Bromo-2-fluoro- benzene, phosphorus trichloride (PCI 3 ), hydrogen chloride gas and n-butyllithium were purchased from Aldrich and used as
  • Deuterated solvents were purchased (toluene-d 8 , THF-ds) and were stored over 4 A sieves. NMR spectra were recorded on a Bruker 300 MHz spectrometer (300.1 MHz for 1 H, 121.5 MHz for 3 P, 282.4 for 19 F).
  • a toluene solution of this mixture and 50 mg of (ortho-F-C 6 H 4 ) 2 PCI was heated at 65°C for three hours to convert the isomer to the desired ligand.
  • the initial steps of the synthesis are conducted in pentane at -5°C (instead of ether) with 0% more of the (ortho-F-C 6 H 4 ) 2 PCI (otherwise as described above).
  • This preferred procedure allows (ortho-F-C6H ) 2 PN(i-Pr)P(ortho- F-C 6 H 4 ) 2 to be formed in high (essentially quantitative) yield without the final step of heating in toluene.
  • the aluminoxane used in all experiments was purchased from Albemarle Corporation and reported to contain 10 weight % aluminum.
  • the product was described as a conventional methylaluminoxane that was prepared using TMA as the only source of an aluminum (i.e., it was not a so-called "modified MAO").
  • the "free TMA” content was reported to be about 0 mole % - i.e. for every 00 moles of aluminum in the product, 90 moles were contained in the aluminbxane oligomer and 10 were present as "free TMA".
  • MAO free TMA
  • a 600 ml_ reactor fitted with a stirrer was purged 3 times with argon while heated at 80°C.
  • the reactor was then cooled to 45°C ( ⁇ 2°C below reaction temperature) and a solution of MAO (1.44 g, 10 weight % MAO) in 65 g of cyclohexane was transferred via a stainless steel cannula to the reactor, followed by 78 g of cyclohexane.
  • Stirrer was started and set to 1700 rpm.
  • the reactor was then pressurized to 35 bar with ethylene and temperature adjusted to 47°C.
  • Ligand 1 (4.43 mg, 0.0089 mmol) and chromium acetylacetonate (3.02 mg, 0.0087 mmol) were premixed in 14.3 g of cyclohexane in a hypovial.
  • the mixture was transferred under ethylene to the pressurized reactor and then the reactor pressure was immediately increased to 40 bar with ethylene.
  • the reaction was allowed to proceed for 15 minutes while maintaining the temperature at 46°C.
  • the reaction was terminated by stopping ethylene flow to the reactor and cooling the contents to 30°C. Stirring was stopped and reactor slowly depressurized to atmospheric pressure. Reactor was then opened and product mixture transferred to a pre-weighed flask containing 1.5 g of isopropanol.
  • the mass of product produced was 100.3 g.
  • a sample of the liquid product was analyzed by GC-FID.
  • a 600 mL reactor fitted with a stirrer was purged 3 times with argon while heated at 80°C.
  • the reactor was then cooled to 45°C ( ⁇ 2°C below reaction temperature) and a solution of MAO (0.44 g, 7.1 weight % Al in MMAO-3A solution in isopentane) topped up to 64.8 g with cyclohexane was transferred via a stainless steel cannula to the reactor, followed by 63.9 g of cyclohexane.
  • Stirrer was started and set to 1700 rpm.
  • the reactor was then pressurized to 30 bar with ethylene, 10.30 g of a cyclohexane solution of isoheptyl-N(P(C 6 H 5 ) 2 )2 (1.295 mg, 2.68 x10 "3 mmol) and chromium acetylacetonate (0.916 mg, 2.68 x10 '3 mmol) was added to the reactor with an additional 5 bar ethylene, and the temperature adjusted to 47°C.
  • a continuous reaction or a semi-batch reaction may also be conducted using the above described start up protocol (i.e. initializing the reaction with MAO only).
  • start up protocol i.e. initializing the reaction with MAO only.
  • a continuous reaction is one in which reactants are continuously added to the reaction (and products are continuously removed) and a semi-batch reaction involves the intermittent addition of reactants and/or the intermittent removal of products. During such reactions, additional catalyst components (i.e.
  • a 600 mL reactor fitted with a stirrer was purged 3 times with argon while heated at 80°C.
  • the reactor was then cooled to 45°C ( ⁇ 2°C below reaction temperature) and a solution of MAO (0.44 g, 7.1 weight % Al in MMAO-3A solution in isopentane) in 70.36 g of cyclohexane was transferred via a stainless steel cannula to the reactor, followed by 55.1 g of chlorobenzene and 19.9 g cyclohexane.
  • the stirrer was started and set to 1700 rpm.
  • the reactor was then pressurized to 30 bar with ethylene, 10.3 g of a cyclohexane solution of i-PrN(P(2-F-C 6 H 4 ) 2 ) 2 (0.934 mg, 2.68 x 0 "3 mmol) and chromium acetylacetonate (1.379 mg, 2.76 x10 "3 mmol) was added to the reactor with an additional 5 bar ethylene, and the temperature adjusted to 47°C.
  • the reaction was allowed to proceed for 15 minutes while maintaining the temperature at 46°C and the pressure at 35 bar, at which point [(octadecyl) 2 MeNH][B(C 6 F 5 ) 4 ] (3.820 mg, 3.10 x10 "3 mmol) in cyclohexane was added to the reactor.
  • the reaction was allowed to proceed for an additional 5 minutes and then terminated by stopping ethylene flow to the reactor and cooling the contents to 30°C. Stirring was stopped and reactor slowly
  • a 600 ml_ reactor fitted with a stirrer was purged 3 times with argon while heated at 80°C.
  • the reactor was then cooled to 45°C ( ⁇ 2°C below reaction temperature) and a solution of MAO (0. 7 g, 7.1 weight % Al in MMAO-3A solution in isopentane) in 106.23 g of chlorobenzene was transferred via a stainless steel cannula to the reactor, followed by 53.4 g of chlorobenzene.
  • the stirrer was started and set to 1732 rpm.
  • the reactor was then pressurized to 30 bar with ethylene, 12.0 g of a chlorobenzene solution of i- PrN(P(2-F-C 6 H 4 ) 2 )2 (0.484 mg, 0.97 x10 "3 mmol) and chromium acetylacetonate (0.327 mg, 0.94 x10 "3 mmol) was added to the reactor with an additional 5 bar ethylene, and the temperature adjusted to 48°C.
  • a new activation system for the catalytic oligomerization of ethylene to alpha olefins is provided.
  • the alpha olefins that are produced by this process are suitable for a wide variety of commercial uses, especially as monomers for the production of thermoplastics.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
  • Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
  • Catalysts (AREA)

Abstract

La présente invention concerne un procédé en deux étapes d'oligomérisation de l'éthylène en présence d'un catalyseur à base de chrome comprenant un ligand diphosphine de pontage. Le procédé permet de réduire les problèmes observés au « démarrage » de l'expérience dans des conditions de régime irrégulier. Le protocole de « démarrage » de ce procédé est caractérisé par l'utilisation d'un activateur aluminoxane et d'une quantité comparativement importante d'un solvant halogéné. Après la phase de démarrage, un second activateur (qui est de préférence un borate non coordinant) est ajouté dans la réaction.
PCT/CA2012/000983 2011-11-08 2012-10-25 Procédé d'oligomérisation de l'éthylène utilisant un solvant aromatique halogéné avec un aluminoxane/des composés organoborés comme activateurs WO2013067620A1 (fr)

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CA2758126A CA2758126C (fr) 2011-11-08 2011-11-08 Procede d'oligomerisation d'ethylene avec de l'aluminoxane/compose organo-bore comme activateurs employant un solvant aromatique halogene

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CN104624235A (zh) * 2013-11-08 2015-05-20 中国石油天然气股份有限公司 一种乙烯齐聚催化剂组合物的制备及应用
WO2016129901A1 (fr) * 2015-02-12 2016-08-18 주식회사 엘지화학 Procédé d'oligomérisation d'oléfines
KR101775239B1 (ko) 2015-02-12 2017-09-05 주식회사 엘지화학 올레핀 올리고머화 방법
CN110494218A (zh) * 2016-12-30 2019-11-22 沙特基础工业全球技术有限公司 用于选择性1-己烯生产的催化剂溶液的制备方法

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Cited By (8)

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Publication number Priority date Publication date Assignee Title
CN104624235A (zh) * 2013-11-08 2015-05-20 中国石油天然气股份有限公司 一种乙烯齐聚催化剂组合物的制备及应用
WO2016129901A1 (fr) * 2015-02-12 2016-08-18 주식회사 엘지화학 Procédé d'oligomérisation d'oléfines
KR101775239B1 (ko) 2015-02-12 2017-09-05 주식회사 엘지화학 올레핀 올리고머화 방법
EP3257871A4 (fr) * 2015-02-12 2018-01-24 LG Chem, Ltd. Agent de désactivation et procédé de réduction de sous-produit d'oligomérisation d'oléfine l'utilisant
JP2018512372A (ja) * 2015-02-12 2018-05-17 エルジー・ケム・リミテッド 非活性化剤及びこれを用いたオレフィンオリゴマー化の副産物低減方法
US10413893B2 (en) 2015-02-12 2019-09-17 Lg Chem, Ltd. Deactivator and method for decreasing by-products in olefin oligomerization using the same
US10688482B2 (en) 2015-02-12 2020-06-23 Lg Chem, Ltd. Method for olefin oligomerization
CN110494218A (zh) * 2016-12-30 2019-11-22 沙特基础工业全球技术有限公司 用于选择性1-己烯生产的催化剂溶液的制备方法

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