Process for removing metals from hydrocarbons

Abstract

This invention relates to a process for removing metals, particularly mercury, from hydrocarbon streams by use of an ionic liquid, where in the metal-containing hydrocarbon stream is contacted with an ionic liquid to produce a product hydrocarbon stream having reduced mercury content.

Claims

1. A process for the removal of mercury from a mercury-containing hydrocarbon fluid feed comprising the steps of: (i) contacting the mercury-containing hydrocarbon fluid feed with an ionic liquid in a hydrocarbon:ionic liquid volume ratio of from 100:1 to 10,000:1, the ionic liquid having the formula [Cat.sup.+][X.sup.]; and (ii) separating from the ionic liquid a hydrocarbon fluid product having a reduced mercury content compared to the mercury-containing hydrocarbon feed; wherein [Cat.sup.+] comprises a cationic species selected from the group consisting of: ##STR00014## ##STR00015## wherein R.sup.a, R.sup.b, R.sup.c, R.sup.d, R.sup.e, R.sup.f, and R.sup.g are each independently selected from hydrogen, a C.sub.1 to C.sub.30, straight chain or branched alkyl group, a C.sub.3 to C.sub.8 cycloalkyl group, or a C.sub.6 to C.sub.10 aryl group, or any two of R.sup.b, R.sup.c, R.sup.d, R.sup.e and R.sup.f attached to adjacent carbon atoms form a methylene chain (CH.sub.2).sub.q wherein q is from 3 to 6; and wherein said alkyl, cycloalkyl or aryl groups, or said methylene chain are unsubstituted or substituted by one to three groups selected from: C.sub.1 to C.sub.6 alkoxy, C.sub.2 to C.sub.12 alkoxyalkoxy, C.sub.3 to C.sub.8 cycloalkyl, C.sub.6 to C.sub.10 aryl, C.sub.7 to C.sub.10 alkaryl, C.sub.7 to C.sub.10 aralkyl, CN, OH, SH, NO.sub.2, CO.sub.2R.sup.x, OC(O)R.sup.x, C(O)R.sup.x, C(S)R.sup.x, CS.sub.2R.sup.x, SC(S)R.sup.x, S(O)(C.sub.1 to C.sub.6)alkyl, S(O)O(C.sub.1 to C.sub.6)alkyl, OS(O)(C.sub.1 to C.sub.6)alkyl, S(C.sub.1 to C.sub.6)alkyl, SS(C.sub.1 to C.sub.6 alkyl), NR.sup.xC(O)NR.sup.yR.sup.z, NR.sup.xC(O)OR.sup.y, OC(O)NR.sup.yR.sup.z, NR.sup.xC(S)OR.sup.y, OC(S)NR.sup.yR.sup.z, NR.sup.xC(S)SR.sup.y, SC(S)NR.sup.yR.sup.z, NR.sup.xC(S)NR.sup.yR.sup.z, C(O)NR.sup.yR.sup.z, C(S)NR.sup.yR.sup.z, NR.sup.yR.sup.z, or a heterocyclic group, wherein R.sup.x, R.sup.y and R.sup.z are independently selected from hydrogen or C.sub.1 to C.sub.6 alkyl; and wherein [X.sup.] comprises an anion selected from [I.sub.3].sup., [I.sub.2Br].sup., [IBr.sub.2].sup., [Br.sub.3].sup., [Br.sub.2C].sup., [BrCl.sub.2].sup., [ICl.sub.2].sup., [I.sub.2Cl].sup., [Cl.sub.3].sup., [N.sub.3].sup., [NCS].sup., [NCSe].sup., [NCO].sup., [CN].sup., [HSO.sub.4].sup., [SO.sub.4].sup.2, [R.sup.2OSO.sub.2O].sup., [HSO.sub.3].sup., [SO.sub.3].sup.2, [R.sup.2OSO.sub.2].sup., [R.sup.1SO.sub.2O].sup., [(R.sup.1SO.sub.2).sub.2N].sup., [H.sub.2PO.sub.4].sup., [HPO.sub.4].sup.2, [PO.sub.4].sup.3, [R.sup.2OPO.sub.3].sup.2, [(R.sup.2O).sub.2PO.sub.2].sup., [H.sub.2PO.sub.3].sup., [HPO.sub.3].sup.2, [R.sup.2OPO.sub.2].sup.2, [(R.sup.2O).sub.2PO].sup., [R.sup.1PO.sub.3].sup.2, [R.sup.1P(O)(OR.sup.2)O].sup., [(R.sup.1SO.sub.2).sub.3C].sup., [bisoxalatoborate], [bismalonatoborate], [R.sup.2CO.sub.2].sup., [3,5-dinitro-1,2,4-triazolate], [4-nitro-1,2,3-triazolate], [2,4-dinitroimidazolate], [4,5-dinitroimidazolate], [4,5-dicyano-imidazolate], [4-nitroimidazolate], [tetrazolate], [R.sup.2OCS.sub.2].sup., [R.sup.2.sub.2NCS.sub.2].sup., [R.sup.1CS.sub.2].sup., [(R.sup.2O).sub.2PS.sub.2].sup., [RS(O).sub.2S].sup., [ROS(O).sub.2S].sup., [NO.sub.3], and [NO.sub.2].sup.; wherein R.sup.1 and R.sup.2 are independently selected from the group consisting of C.sub.1-C.sub.10 alkyl, C.sub.6 aryl, C.sub.1-C.sub.10 alkyl(C.sub.6)aryl, and C.sub.6 aryl(C.sub.1-C.sub.10)alkyl each of which is unsubstituted or substituted by one or more groups selected from: fluoro, chloro, bromo, iodo, C.sub.1 to C.sub.6 alkoxy, C.sub.2 to C.sub.12 alkoxyalkoxy, C.sub.3 to C.sub.8 cycloalkyl, C.sub.6 to C.sub.10 aryl, C.sub.7 to C.sub.10 alkaryl, C.sub.7 to C.sub.10 aralkyl, CN, OH, SH, NO.sub.2, CO.sub.2R.sup.x, OC(O)R.sup.x, C(O)R.sup.x, C(S)R.sup.x, CS.sub.2R.sup.x, SC(S)R.sup.x, S(O)(C.sub.1 to C.sub.6)alkyl, S(O)O(C.sub.1 to C.sub.6)alkyl, OS(O)(C.sub.1 to C.sub.6)alkyl, S(C.sub.1 to C.sub.6)alkyl, SS(C.sub.1 to C.sub.6 alkyl), NR.sup.xC(O)NR.sup.yR.sup.z, NR.sup.xC(O)OR.sup.y, OC(O)NR.sup.yR.sup.z, NR.sup.xC(S)OR.sup.y, OC(S)NR.sup.yR.sup.z, NR.sup.xC(S)SR.sup.y, SC(S)NR.sup.yR.sup.z, NR.sup.xC(S)NR.sup.yR.sup.z, C(O)NR.sup.yR.sup.z, C(S)NR.sup.yR.sup.z, NR.sup.yR.sup.z, or a heterocyclic group, wherein R.sup.x, R.sup.y and R.sup.z are independently selected from hydrogen or C.sub.1 to C.sub.6 alkyl, and wherein R.sup.1 may also be fluorine, chlorine, bromine or iodine.

2. A process according to claim 1, wherein the mercury is in elemental, particulate, or organic form.

3. A process according to claim 1, wherein the mercury concentration in the mercury-containing hydrocarbon fluid feed is from about 1 to about 50,000 parts per billion.

4. A process according to claim 1, wherein the mercury-containing hydrocarbon fluid feed is a liquid.

5. A process according to claim 4, wherein the mercury-containing hydrocarbon fluid feed includes at least one member of a group comprising: (i) a liquefied natural gas; (ii) a light distillate comprising liquid petroleum gas, gasoline, and/or naphtha; (iii) a natural gas condensate; (iv) a middle distillate comprising kerosene and/or diesel; (v) a heavy distillate; and (vi) a crude oil.

6. A process according to claim 1, wherein the mercury-containing hydrocarbon fluid feed is a gas.

7. A process according to claim 6, wherein the mercury-containing hydrocarbon fluid feed includes at least one member of a group comprising: natural gas and refinery gas.

8. A process according to claim 1, wherein [Cat.sup.+] comprises a cationic species selected from the group consisting of: ##STR00016## R.sup.a, R.sup.b, R.sup.c, R.sup.d, R.sup.e, R.sup.f and R.sup.g are as defined in claim 1.

9. A process according to according to claim 8 wherein [Cat.sup.+] comprises a cationic species selected from the group consisting of: ##STR00017## R.sup.a, R.sup.b, R.sup.c, R.sup.d, R.sup.e, R.sup.f, and R.sup.g are as defined in claim 1.

10. A process according to claim 9 wherein [Cat.sup.+] comprises a cationic species selected from the group consisting of: ##STR00018## R.sup.a and R.sup.g are as defined in claim 1.

11. A process according to claim 10, wherein the cationic species is: ##STR00019## wherein: R.sup.a is selected from a C.sub.2 to C.sub.20, linear or branched alkyl group (such as methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, n-heptadecyl and n-octadecyl) and R.sup.g is selected from a C.sub.1 to C.sub.5, linear or branched alkyl group (such as methyl, ethyl, n-propyl, n-butyl and n-pentyl).

12. A process according to claim 1, wherein [Cat.sup.+] comprises a cationic species selected from the group consisting of: ##STR00020## R.sup.a, R.sup.b, R.sup.c, R.sup.d, R.sup.e, R.sup.f, and R.sup.g are as defined in claim 1.

13. A process according to claim 1, wherein [Cat.sup.+] is selected from the group consisting of: ##STR00021## R.sup.a, R.sup.b, R.sup.c, R.sup.d, R.sup.e, and R.sup.f are as defined in claim 1.

14. A process according to claim 1, wherein [X.sup.] comprises an anion selected from [I.sub.3].sup., [I.sub.2Br].sup., [IBr.sub.2].sup., [Br.sub.3].sup., [Br.sub.2C].sup., [BrCl.sub.2].sup., [ICl.sub.2].sup., [I.sub.2Cl].sup., and [Cl.sub.3].sup..

15. A process according to claim 14, wherein the anion is a perhalide selected from [I.sub.3].sup., [I.sub.2Br].sup., [IBr.sub.2].sup., [Br.sub.3].sup., [Br.sub.2Cl].sup., [BrCl.sub.2].sup., [ICl.sub.2].sup., [I.sub.2Cl].sup. and [Cl.sub.3].sup..

16. A process according to claim 1, wherein [X.sup.] comprises an anion selected from [NO.sub.3].sup., [NO.sub.2].sup., [H.sub.2PO.sub.4].sup., [HPO.sub.4].sup.2, [PO.sub.4].sup.3, [R.sub.2OPO.sub.3].sup.2, [(R.sup.2O).sub.2PO.sub.2].sup., [H.sub.2PO.sub.3].sup., [HPO.sub.3].sup.2, [R.sup.2OPO.sub.2].sup.2, [(R.sup.2O).sub.2PO].sup., [R.sup.1PO.sub.3].sup.2, [R.sup.1P(O)(OR.sup.2)O].sup., and [R.sup.2CO.sub.2].sup. wherein R.sup.1 and R.sup.2 are as defined in claim 1.

17. A process according to claim 1, wherein [X.sup.] comprises an anion having an electron-rich sulfur or selenium moiety, said anion being selected from [NCS].sup., [NCSe].sup., [R.sup.2OCS.sub.2].sup., [R.sup.2.sub.2NCS.sub.2].sup., [R.sup.1CS.sub.2].sup., [(R.sup.2O).sub.2PS.sub.2].sup., [R.sup.1S(O).sub.2S].sup., [R.sup.2OS(O).sub.2S].sup., wherein R.sup.1 and R.sup.2 are as defined in claim 1, and anions as defined in claim 1 comprising thiol, thioether, or disulfide substituents.

18. A process according to claim 1, wherein [X.sup.] comprises an anion selected from [HSO.sub.4].sup., [SO.sub.4].sup.2, [R.sup.2OSO.sub.2O].sup., [HSO.sub.3].sup., [SO.sub.3].sup.2, [R.sup.2OSO.sub.2].sup., and [R.sup.1SO.sub.2O].sup. wherein R.sup.1 and R.sup.2 are as defined in claim 1.

19. A process according to claim 1, wherein the ionic liquid is immobilised on an inert solid support.

20. A process according to claim 19, wherein the inert solid support is activated carbon.

21. A process according to claim 19, wherein the inert solid support is silica.

22. A process according to claim 1, wherein the ionic liquid is immiscible with the mercury-containing hydrocarbon fluid feed and the hydrocarbon fluid product.

23. A process according to claim 1, wherein the ionic liquid is contacted with the mercury-containing hydrocarbon fluid feed at a temperature of from 80 C. to 200 C.

24. A process according to claim 1, wherein the ionic liquid is contacted with the mercury-containing hydrocarbon fluid feed at atmospheric pressure.

25. A process according to claim 1, wherein the ionic liquid is in liquid form when contacted with the mercury-containing hydrocarbon fluid feed.

26. A process according to claim 1, wherein 1 to 10,000 moles of ionic liquid are contacted with the mercury-containing hydrocarbon fluid feed per mole of the mercury in the mercury-containing hydrocarbon fluid feed.

27. A process according to claim 1, wherein the hydrocarbon fluid product comprises 10% or less of the mercury content of the mercury-containing hydrocarbon feed.

28. A process according to claim 27, wherein the hydrocarbon fluid product comprises 5% or less of the mercury content of the mercury-containing hydrocarbon feed.

29. A process according to claim 28, wherein the hydrocarbon fluid product comprises 1% or less of the mercury content of the mercury-containing hydrocarbon feed.

30. A process according to claim 1, wherein the mercury-containing hydrocarbon feed and the ionic liquid are contacted by means of a continuous process or a batch process.

31. A process according to claim 30, wherein the mercury-containing hydrocarbon feed and the ionic liquid are contacted from about 1 minute to about 60 minutes.

32. A process according to claim 1, wherein the hydrocarbon:ionic liquid volume ratio is from 1000:1 to 10,000:1.

Description

EXAMPLES

(1) Removal of Mercury from a Natural Gas Condensate

(2) In a test process, equal masses of a natural gas condensate (NGC) and ionic liquid were stirred for 4 hours at 25 C. The stirring was then stopped and the ionic liquid separated as a lower dense phase and the mixtures were left to stand for 15 hours to ensure equilibration. Multiple samples from the condensate phases (30 mg each) were taken without disturbing the liquid-liquid interface and the total mercury content determined using a Milestone DMA-80 pyrolysis/AA analyser. Mercury contents determined are shown in micrograms per kilogram with standard deviations from duplicate runs in parentheses.

(3) After contacting natural gas condensate with all the ionic liquids described, the mercury content of the natural gas condensate was reduced to below 14 g kg.sup.1 except in the case of contacting with 1-ethyl-3-methylimidazolium ethylsulfate.

Example 1: 1-butyl-3-methylimidazolium bis(trifluoromethane)sulfonimide

(4) NGC (4.1 g) was mixed with 1-butyl-3-methylimidazolium bis(trifluoromethane)sulfonimide (4.1 g). The mercury content of the condensate phase after contacting was 7 (3) g kg.sup.1 compared to the NGC control sample that contained 99 (10) g kg.sup.1 of mercury.

Example 2: 1-butyl-3-methylimidazolium chlorodibromide

(5) NGC (4.2 g) was mixed with 1-butyl-3-methylimidazolium chlorodibromide (4.2 g). The mercury content of the condensate phase after contacting was 11 (9) g kg.sup.1 compared to the NGC control sample that contained 99 (10) g kg.sup.1 of mercury.

Example 3: 1-ethyl-3-methylimidazolium ethylsulfate

(6) NGC (4.1 g) was mixed with 1-ethyl-3-methylimidazolium ethylsulfate (4.0 g). The mercury content of the condensate phase after contacting was 73 (13) g kg.sup.1 compared to the NGC control sample that contained 99 (10) g kg.sup.1 of mercury.

Example 4: 1-hexyl-3-methylimidazolium bis(trifluoromethane)sulfonimide

(7) NGC (2.0 g) was mixed with 1-hexyl-3-methylimidazolium bis(trifluoromethane)sulfonimide (2.0 g). The mercury content of the condensate phase after contacting was 4 (1) g kg.sup.1 compared to the NGC control sample that contained 99 (10) g kg.sup.1 of mercury.

Example 5: 1-butyl-4-cyanopyridinium bis(trifluoromethane)sulfonimide

(8) NGC (2.0 g) was mixed with 1-butyl-4-cyanopyridinium bis(trifluoromethane)sulfonimide (2.0 g). The mercury content of the condensate phase after contacting was 7 (5) g kg.sup.1 compared to the NGC control sample that contained 99 (10) g kg.sup.1 of mercury.

Example 6: 1-butyl-3-methylimidazolium diethyldithiophosphate

(9) NGC (4.0 g) was mixed with 1-butyl-3-methylimidazolium diethyldithiophosphate (4.0 g). The mercury content of the condensate phase after contacting was 5 (5) g kg.sup.1 compared to the initial NGC sample that contained 532 (23) g kg.sup.1 of mercury.

Example 7: 1-butyl-3-methylimidazolium thiocyanate

(10) NGC (4.0 g) was mixed with 1-butyl-3-methylimidazolium thiocyanate (4.0 g). The mercury content of the condensate phase after contacting was 5 (1) g kg.sup.1 compared to the initial NGC sample that contained 532 (23) g kg.sup.1 of mercury.

Example 8: 1-butyl-3-methylimidazolium methoxytri(propylene glycol)sulfate

(11) NGC (4.0 g) was mixed with 1-butyl-3-methylimidazolium methoxytri(propylene glycol)sulfate (4.0 g). The mercury content of the condensate phase after contacting was 9 (4) g kg.sup.1 compared to the initial NGC sample that contained 532 (23) g kg.sup.1 of mercury.

Example 9: 1-butyl-3-methylimidazolium acetate

(12) NGC (4.0 g) was mixed with 1-butyl-3-methylimidazolium acetate (4.0 g). The mercury content of the condensate phase after contacting was 14 g kg.sup.1 compared to the initial NGC sample that contained 532 (23) g kg.sup.1 of mercury.

Example 10: 1-ethyl-3-methylimidazolium hydrogensulfate

(13) NGC (4.0 g) was mixed with 1-ethyl-3-methylimidazolium hydrogensulfate (4.0 g). The mercury content of the condensate phase after contacting was 8 (5) g kg.sup.1 compared to the initial NGC sample that contained 532 (23) g kg.sup.1 of mercury.

(14) Removal of Mercury from Dodecane Spiked with Elemental Mercury

(15) In test processes, known masses of dodecane that had been previously saturated with mercury with an ionic liquid were stirred with ionic liquids at a fixed temperature for a measured period of time. The stirring was then stopped and the ionic liquid separated as a lower dense phase and the mixtures were left to stand for 15 min. to ensure separation of the phases. Multiple samples from the condensate phases (30 mg each) were taken without disturbing the liquid-liquid interface and the total mercury content determined using a Milestone DMA-80 pyrolysis/AA analyser. Mercury contents determined are shown in micrograms per kilogram with standard deviations from duplicate runs in parentheses.

Example 11: Removal of Mercury from Dodecane with 1-butyl-3-methylimidazolium thiocyanate

(16) Dodecane (20 g) containing 3978 g kg.sup.1 of mercury was stirred with 1-butyl-3-methylimidazolium thiocyanate (2.0 g) at 60 C. for 15 h. The mercury content of the dodecane phase decreased to 20 (5) g kg.sup.1 and the mercury content of the ionic liquid extractant increased to 53143 (2830) g kg.sup.1.

Example 12: Removal of Mercury from Dodecane with 1-butyl-3-methylimidazolium thiocyanate

(17) Dodecane (20 g) containing 3978 g kg.sup.1 of mercury was stirred with 1-butyl-3-methylimidazolium thiocyanate (0.2 g) at 60 C. for 15 h. The mercury content of the dodecane phase decreased to 35 (2) g kg.sup.1, the dodecane was decanted off and a further batch of dodecane containing 4551 g kg.sup.1 of mercury was added and stirred for 18 h. The mercury content of the dodecane decreased to 43 (4) g kg.sup.1.

Example 13: Removal of Mercury from Dodecane with 1-methylimidazolium camphor sulfonate

(18) Dodecane (2.4 g) containing 3500 g kg.sup.1 of mercury was stirred with 1-5 methylimidazolium camphor sulfonate (1.2 g) at 21 C. for 6 h. The mercury content of the dodecane phase decreased to 60 g kg.sup.1. The concentration of mercury in the dodecane phase remained constant after stirring was continued for 24 hours.

Example 14: Removal of Mercury from Dodecane with Tributylammonium Lipoate

(19) Dodecane (3.1 g) containing 3500 g kg.sup.1 of mercury was stirred with tributylammonium lipoate (2.2 g) at 21 C. for 6 h. The mercury content of the dodecane phase decreased to 95 g kg.sup.1. After stirring for 24 hours, the concentration of mercury in the dodecane phase was reduced to 30 g kg.sup.1. The concentration of mercury in the dodecane phase remained constant after stirring was continued for a further 24 hours.

Example 15: Removal of Mercury from Dodecane with Tricaprylmethylammonium Dithiobenzoate

(20) Dodecane (4.5 g) containing 3500 g kg.sup.1 of mercury was stirred with tricaprylmethylammonium dithiobenzoate (1.2 g) at 50 C. for 24 h. The mercury content of the dodecane phase decreased to 40 g kg.sup.1.

Example 16: Removal of Mercury from Dodecane with Tetrabutylphosphonium Dithiobutyrate

(21) Dodecane (1.4 g) containing 3500 g kg.sup.1 of mercury was stirred with tetrabutylphosphonium dithiobutyrate (1.1 g) at 50 C. for 24 h. The mercury content of the dodecane phase decreased to 190 g kg.sup.1. After stirring for a further 24 hours, the concentration of mercury in the dodecane phase was reduced to 80 g kg.sup.1.

Example 17: Removal of Mercury from Dodecane with Choline Lipoate

(22) Dodecane (3.0 g) containing 3500 g kg.sup.1 of mercury was stirred with choline lipoate (0.9 g) at 50 C. for 24 h. The mercury content of the dodecane phase decreased to 290 g kg.sup.1.

Example 18: Removal of Mercury from Dodecane with 1-butyl-3-methylimidazolium salicylate

(23) Dodecane (4.0 g) containing 3500 g kg.sup.1 of mercury was stirred with 1-butyl-3-methylimidazolium salicylate (2.9 g) at 50 C. for 48 h. The mercury content of the dodecane phase decreased to 220 g kg.sup.1.

Example 19: Removal of Mercury from Dodecane with Choline Decanoate

(24) Dodecane (3.0 g) containing 3500 g kg.sup.1 of mercury was stirred with choline decanoate (1.5 g) at 50 C. for 48 h. The mercury content of the dodecane phase decreased to 270 g kg.sup.1.

Example 20: Removal of Mercury from Dodecane with 1-butyl-1-methylpyrrolidinium tris(pentafluoroethyptrifluorophosphate

(25) Dodecane (1.57 g) containing 2200 ppb of elemental mercury was stirred with 1-butyl-1-methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate (0.53 g) at 60 C. for 24 h. The mercury content of the dodecane phase decreased to 1587 ppb and the mercury content of the ionic liquid extractant increased to 963 ppm (28% of the available mercury was extracted into the ionic liquid).