Olefin oligomerization reaction processes exhibiting reduced fouling

• US 8,227,653 B2
• Filed: 03/27/2009
• Issued: 07/24/2012
• Est. Priority Date: 03/27/2009
• Status: Active Grant

• Current Assignee: ExxonMobil Chemical Patents Inc. (Exxon Mobil Corporation)
• Original Assignee: ExxonMobil Chemical Patents Inc. (Exxon Mobil Corporation)
• Inventors: Weber, Michael W., Lattner, James R., McCullough, Laughlin G., Dickey, Randell W., Brown, Steven D., Loezos, Peter N.
• Primary Examiner(s): Teskin, Fred M
• Application Number:
  US13/203,590
• Publication Number:
  US 20120016097A1
• Time in Patent Office: 1,215 Days
• Field of Search: 585/527, 585/950, 585/520, 526/75
• US Class Current: 585/527
• CPC Class Codes: C07C 11/02 Alkenes
• CPC Class Codes: C07C 2/30 containing metal-to-carbon bond; Metal hydrides
• CPC Class Codes: C07C 2521/08 Silica
• CPC Class Codes: C07C 2531/12 containing organo-metallic compounds or metal hydrides
• CPC Class Codes: C07C 7/20 Use of additives, e.g. for stabilisation
• CPC Class Codes: C08F 2/005 by addition of a scale inhibitor to the polymerisation medium
• CPC Class Codes: C08F 255/00 Macromolecular compounds obtained by polymerising monomers on to polymers of hydrocarbons as defined in group C08F10/00
• CPC Class Codes: C08F 255/02 on to polymers of olefins having two or three carbon atoms
• CPC Class Codes: C08F 297/08 polymerising mono-olefins
• CPC Class Codes: C08F 297/083 the monomers being ethylene or propylene
• CPC Class Codes: C08L 2666/02 Organic macromolecular compounds, natural resins, waxes or and bituminous materials
• CPC Class Codes: C08L 51/06 grafted on to homopolymers or copolymers of aliphatic hydrocarbons containing only one carbon-to-carbon double bond
• CPC Class Codes: Y10S 585/95 Prevention or removal of corrosion or solid deposits

Abstract

The invention relates to olefin oligomerization methods and methods for reducing/inhibiting fouling in olefin oligomerization reactions comprising: contacting, in an oligomerization reactor (e.g., under oligomerization conditions), an alpha-olefin feed, a catalyst having an olefin selectivity of at least 90 mol % to a desired oligomerization product, a polymer anti-foulant, and optionally a diluent; selectively producing an effluent comprising the desired oligomerization product, unreacted olefin, and alpha-olefin-based polymer byproduct that causes fouling. The amount of polymer anti-foulant can be chosen to limit fouling to ≦20 g/kg desired oligomerization product, to remediate ≧3 grams fouled polymer/kg desired oligomerization product, and/or to reduce/inhibit polymer fouling by ≧10% over a selective oligomerization with substantially no added polymer anti-foulant. Advantageously, desired oligomerization product so obtained can also be polymerized/copolymerized with an alpha-olefin such as ethylene.

Claims

1. A method for oligomerizing olefins comprising:

contacting, in an oligomerization reactor under oligomerization conditions, a feed comprising an alpha-olefin, a catalyst having an olefin selectivity of at least 90 mol % to a desired oligomerization product, and optionally a diluent;

producing an effluent comprising the desired oligomerization product, unreacted olefin, and polymer byproduct having at least 50 mol % of its repeat units based on the alpha-olefin and which causes fouling on one or more surfaces within the oligomerization reactor; and

adding a polyethylene homopolymer or copolymer anti-foulant to the oligomerization reactor.

2. The method of claim 1, wherein the anti-foulant is added in an amount sufficient to (i) limit fouling on the one or more surfaces within the oligomerization reactor to no more than 20 grams of polymer byproduct per kilogram of desired oligomerization product, (ii) remediate, per kilogram of desired oligomerization product, at least 3 grams of polymer byproduct that has fouled on the one or more surfaces within the oligomerization reactor, or (iii) both (i) and (ii).

3. The method of claim 1, further comprising the step of separating the desired oligomerization product from the effluent to attain an olefinic purity of desired oligomerization product of at least 98 mol %.

4. The method of claim 1, wherein the catalyst comprises the combination of:

a) a ligand represented by the formula;

5. The method of claim 1, wherein the feed comprises greater than about 99 wt % ethylene.

6. The method of claim 4, wherein the ligand of the catalyst is represented by at least one of the following formulas:

7. The method of claim 1, wherein the diluent is present and is selected from the group consisting of 1-butene, 1-hexene, 1-octene, toluene, propane, butane, isobutane, pentane, isopentane, and combinations thereof.

8. The method of claim 1, wherein the oligomerization conditions comprise a reaction temperature from about 60°

C. to about 150°

C., a reaction pressure from about 300 psi (21.1 kg/cm²) to about 900 psi (63.3 kg/cm²), and a reaction residence time from about 30 minutes to about 4 hours.

9. The method of claim 1, wherein the desired oligomerization product is selected from the group consisting of 1-butene, 1-hexene, 1-octene, 1-decene, and mixtures thereof.

10. The method of claim 9, wherein the catalyst has an olefin selectivity of at least 95 mol % to the desired oligomerization product.

11. The method of claim 9, wherein the catalyst has an olefin selectivity of at least 97 mol % to the desired oligomerization product.

12. The method of claim 9, wherein the catalyst has an olefin selectivity of at least 95 mol % to the desired oligomerization product, which is two olefins selected from the group consisting of 1-butene, 1-hexene, 1-octene, and 1-decene.

13. The method of claim 1, wherein one or more of the following are satisfied:

the anti-foulant has a density of at least about 0.921 g/cm³;

the anti-foulant has an average particle size, d₅₀, of at least about 100 microns;

the anti-foulant comprises a polyethylene homopolymer or a polyethylene copolymer having less than about 6 wt % comonomer repeat units;

the amount of anti-foulant is sufficient to limit fouling on the one or more surfaces within the oligomerization reactor to no more than 10 grams of polymer byproduct per kilogram of desired oligomerization product;

the alpha-olefin comprises ethylene;

the desired oligomerization product comprises 1-hexene, 1-octene, 1-decene, or a combination thereof;

the polymer byproduct comprises a polyethylene (co)polymer;

the diluent is selected from the group consisting of one or more C₃-C₈ linear, branched, and/or cyclic hydrocarbons; and

the anti-foulant reduces and/or inhibits fouling in the oligomerization reactor by at least 10% over a selective oligomerization with substantially no added anti-foulant.

14. A method for polymerizing a polyethylene copolymer comprising

contacting, in an oligomerization reactor under oligomerization conditions, a feed comprising an alpha-olefin, a catalyst having an olefin selectivity of at least 90 mol % to a desired oligomerization product, and optionally a diluent;

adding a polyethylene homopolymer or copolymer anti-foulant to the oligomerization reactor;

producing an effluent comprising the desired oligomerization product, unreacted olefin, and polymer byproduct having at least 50 mol % of its repeat units based on the alpha-olefin and which causes fouling on one or more surfaces within the oligomerization reactor; and

contacting ethylene and the desired oligomerization product in a polymerization reactor under conditions sufficient to form a polyethylene copolymer.

15. A method for reducing and/or inhibiting polymeric fouling in an olefin oligomerization process, the method comprising:

selectively oligomerizing an alpha-olefin by contacting in an oligomerization reactor a feed comprising the alpha-olefin, a polyethylene homopolymer or copolymer anti-foulant, optionally a diluent, and a catalyst having an olefin selectivity of at least 90 mol % to a desired oligomerization product under reaction conditions sufficient to produce an effluent comprising the desired oligomerization product, unreacted olefin, and reaction byproducts comprising at least a (co)polymer having at least 50 mol % of its repeat units based on the alpha-olefin, said (co)polymer causing fouling in the oligomerization reactor in the absence of the anti-foulant, wherein the selective oligomerization containing the anti-foulant reduces and/or inhibits fouling in the oligomerization reactor by at least 10% over a selective oligomerization with substantially no added anti-foulant.

16. A method for oligomerizing olefins comprising:

contacting, in an oligomerization reactor under oligomerization conditions, a feed comprising an alpha-olefin, a catalyst having an olefin selectivity of at least 90 mol % to a desired oligomerization product, and optionally a diluent;

producing an effluent comprising the desired oligomerization product, unreacted olefin, and polymer byproduct having at least 50 mol % of its repeat units based on the alpha-olefin and which causes fouling on one or more surfaces within the oligomerization reactor; and

adding an anti-foulant comprising an polyethylene homopolymer or an unmodified polyethylene copolymer having less than about 6 wt % comonomer repeat units to the oligomerization reactor.

17. The method of claim 16, wherein the anti-foulant has an average particle size, d₅₀, of at least about 100 microns.