Process for removing metals from hydrocarbons

Abstract

Mercury is removed from a mercury-containing hydrocarbon fluid feed by utilizing ionic liquids. The mercury-containing hydrocarbon fluid feed is contacted with a metallate salt immobilized on a solid support material. A hydrocarbon fluid product having a reduced mercury content compared to the mercury-containing fluid feed is separated from the ionic liquid.

Claims

1. A process for the removal of mercury from a mercury-containing hydrocarbon fluid feed, the process comprising the steps of: (i) contacting the mercury-containing hydrocarbon fluid feed with a metallate salt immobilised on a solid support material, where the metallate salt has the formula:
[Q.sup.+][(M.sup.x+).sub.n(L.sup.y).sub.m].sup.(nxmy) wherein: each M.sup.x+ independently represents one or more metal cations selected from transition metal cations having a charge of x+; each L.sup.y independently represents a ligand having a charge of y; n is 1,2 or 3; m is 2, 3, 4, 5, 6, 7 or 8; x is 2, 3, 4, 5 or 6; y is 1, 2, or 3, (nxmy) is a negative number, and [Q.sup.+] represents one or more inorganic cations having a total charge of (mynx); and (ii) separating from the metallate salt a hydrocarbon fluid product having a reduced mercury content compared to the mercury-containing fluid feed.

2. A process according to claim 1, wherein each L.sup.y is an anionic species independently selected from halides, perhalides, pseudohalides, sulphates, sulphites, sulfonates, sulfonimides, phosphates, phosphites, phosphonates, methides, borates, carboxylates, azolates, carbonates, carbamates, thiophosphates, thiocarboxylates, thiocarbamates, thiocarbonates, xanthates, thiosulfonates, thiosulfates, nitrate, nitrite, perchlorate, halometallates, amino acids and borates [O.sup.2] and [S.sup.2].

3. A process according to claim 2, wherein each L.sup.y is an anionic species independently selected from [F].sup., [Cl].sup., [Br].sup., [I].sup., [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.2CI].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-dicyanoimidazolate], [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.

4. A process according to claim 3, wherein at least one of the alkyl or aryl groups is 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)(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, and 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.

5. A process according to claim 4, wherein R.sup.1 is selected from the group consisting of fluorine, chlorine, bromine and iodine.

6. A process according to claim 3, wherein each L.sup.y is an anionic species independently selected from [F].sup., [Cl].sup., [Br].sup., [I].sup., [N.sub.3].sup., [NCS].sup., [NCSe].sup., [NCO].sup., [CN].sup., [R.sup.2CO.sub.2].sup., [O].sup.2 and [S].sup.2.

7. A process according to claim 6, wherein the metallate salt comprises a metallate anion selected from the group consisting of [FeCl.sub.4].sup., [CuCl.sub.4].sup.2, [Cu.sub.2Cl.sub.6].sup.2 and [MoS.sub.4].sup.2.

8. A process according to claim 1, wherein [Q.sup.+] represents one or more ions selected from the group consisting of [Li].sup.+, [Na].sup.+, [K].sup.+, [Mg].sup.2+, [Ca].sup.2+, and [NH.sub.4].sup.+.

9. A process according to claim 1, wherein the solid support material comprises a porous support material having a BET surface area of from 10 m.sup.2.Math.g.sup.1 to 3000 m.sup.2.Math.g.sup.1.

10. A process according to claim 1, wherein the solid support material comprises a porous support material having a BET surface area of from 100 m.sup.2.Math.g.sup.1 to 300 m.sup.2.Math.g.sup.1.

11. A process according to claim 1, wherein the solid support material is selected the group consisting of silica, alumina, silica-alumina, and activated carbon.

12. A process according to claim 1, wherein the solid support material is selected from the group consisting of silica and activated carbon.

13. A process according to claim 1, wherein the solid-supported metallate salt is contacted with the mercury-containing hydrocarbon fluid feed at a temperature of from 0 C. to 250 C.

14. A process according to claim 1, wherein the solid-supported metallate salt is contacted with the mercury-containing hydrocarbon fluid feed at atmospheric pressure.

15. A process according to claim 1, wherein the mercury-containing hydrocarbon feed and the solid-supported metallate salt are contacted for a period of from 0.1 minute to 5 hours.

16. A process according to claim 1, wherein the hydrocarbon fluid product contains less than 40 wt % of the mercury content of the mercury-containing hydrocarbon fluid feed.

17. A process according to claim 16, wherein the hydrocarbon fluid product contains less than 5 wt % of the mercury content of the mercury-containing hydrocarbon fluid feed.

18. A process according to claim 1, wherein the hydrocarbon fluid product contains less than 50 ppb mercury.

19. A process according to claim 18, wherein the hydrocarbon fluid product contains less than 1 ppb mercury.

Description

(1) The present invention will now be described by way of example and by reference to the accompanying figures, in which:

(2) FIG. 1 is a graph showing a comparison of the extractive capacity of ionic liquids having metallate anions, non-ionic liquid metallate salts, and non-ionic liquid non-metallate salts.

(3) FIG. 2 is a graphical representation of the data in Table 8, showing a comparison of the capacity of ionic liquids supported on activated carbon and porous silicas and a commercial sulfur-impregnated activated carbon to remove mercury from a gas stream.

EXAMPLES

(4) As used in the following examples: [C.sub.nmim] refers to a 1-alkyl-3-methylimidazolium cation in which the alkyl group contains n carbon atoms [N.sub.w,x,y,z] refers to a tetraalkylammonium cation in which the alkyl groups have w, x, y and z carbon atoms respectively. [P.sub.w,x,y,z] refers to a tetraalkylphosphonium cation in which the alkyl groups have w, x, y and z carbon atoms respectively.

Example 1: Extraction of Elemental Mercury by Copper-Containing Ionic Liquids

(5) 1-Butyl-3-methylimidazolium chloride (5 g, 29 mmol) and copper(II) chloride dihydrate (5 g, 29 mmol) were combined in a flask and heated to 70 C. under vacuum to give a yellow-brown viscous oil.

(6) 0.037 g of the oil was contacted with 0.0183 g elemental mercury and heated in a sealed tube to 60 C. overnight to yield a pale, slightly blue ionic liquid containing a pale off white precipitate. 10 cm.sup.3 of deionised water was added to the mixture, filtered, and diluted to 50 cm.sup.3. 1 cm.sup.3 of the diluted solution was further diluted to 50 cm.sup.3 with deionised water. The resulting solution was analysed for mercury using a Milestone DMA-80 direct mercury analyser. The solution was found to contain 3.270.21 ppm mercury, demonstrating that 0.22 g of mercury per gram of initial ionic liquid had been converted into a water soluble ionic form, compared to a theoretical uptake of 0.294 g/g mercury based on two electron reduction of Cu(II) to Cu(I).

Example 2: Extraction of Elemental Mercury by Copper-Containing Ionic Liquids

(7) The copper(II)-containing ionic liquid of Example 1 was contacted with 0.355 g elemental mercury and heated in a sealed tube to 60 C. overnight. The resulting mixture was analysed as in Example 1 and was found to contain 7.020.24 ppm mercury in the analyte solution, corresponding to 18.6 wt % mercury solubilised.

Example 3: Extraction of Elemental Mercury from Dodecane

(8) An ionic liquid was prepared from a 2:1 molar ratio of 1-butyl-3-methylimidazolium chloride and copper(II) chloride dihydrate. 0.18 g of the ionic liquid was added to a sample vial with 10 cm.sup.3 of dodecane containing 1000 ppm of elemental mercury, and the resulting mixture was stirred overnight at 60 C. The resulting dodecane phase was then analysed for total mercury concentration and was found to contain 34.9 ppb of mercury.

Example 4: Extraction of Mercury(II) Chloride from Dodecane

(9) An ionic liquid was prepared from a 2:1 molar ratio of 1-butyl-3-methylimidazolium chloride and copper(II) chloride dihydrate. 0.275 g of the ionic liquid was added to a sample vial with 10 cm.sup.3 of dodecane and 0.069 g of HgCl.sub.2, corresponding to a total mercury content of 8115 ppm, and the resulting mixture was stirred overnight at 60 C. The resulting dodecane phase was then analysed for total mercury concentration and was found to contain 42.75 ppb of mercury. The ionic liquid was found to contain 176,000 ppm of mercury.

(10) A further charge of 0.0397 g of HgCl.sub.2 was then added to the mixture and stirred for one hour at 60 C. The resulting dodecane phase was then analysed for total mercury concentration and was found to contain 96.75 ppb of mercury, i.e. 0.46% of the initial mercury concentration. The ionic liquid was found to contain 292,000 ppm of mercury.

Example 5: Extraction of Mercury(II) Oxide from Dodecane

(11) An ionic liquid was prepared from a 2:1 molar ratio of 1-butyl-3-methylimidazolium chloride and copper(II) chloride dihydrate. 0.22 g of the ionic liquid was added to a sample vial with 10 cm.sup.3 of dodecane and 0.0114 g of HgO corresponding to a total mercury content of 1696 ppm, and the resulting mixture was stirred overnight at 60 C. The resulting dodecane phase was then analysed for total mercury concentration and was found to contain 13.25 ppb of mercury. The ionic liquid was found to contain 4.8 wt % of mercury.

(12) A further charge of 0.0152 g of HgO was then added to the mixture and stirred for one hour at 60 C. The resulting dodecane phase was then analysed for total mercury concentration and was found to contain 69.95 ppb of mercury. The ionic liquid was found to contain 11.1 wt % of mercury.

Example 6: Extraction of Elemental Mercury from Dodecane

(13) An ionic liquid was prepared from a 2:1 molar ratio of 1-butyl-3-methylimidazolium chloride and copper(II) chloride dihydrate. 0.23 g of the ionic liquid was added to a sample vial with 10 cm.sup.3 of dodecane containing 0.0488 g of elemental mercury, and the resulting mixture was stirred overnight at 60 C. The resulting dodecane phase was then analysed for total mercury concentration and was found to contain 946.7 ppb of mercury. The ionic liquid was found to contain 21.2 wt % of mercury. The resultant mixture contained IL saturated with mercury, hydrocarbon saturated with mercury and a small amount of dispersed elemental mercury.

(14) A further charge of 0.0768 g of the ionic liquid was then added to the mixture and stirred for one hour at 60 C. The resulting dodecane phase was then analysed for total mercury concentration and was found to have been reduced to 65.55 ppb of mercury.

(15) The results of Examples 3 to 6 are shown in Table 1.

(16) TABLE-US-00001 TABLE 1 Initial [Hg] in Final [Hg] in Example No. System/ppm C.sub.12/ppb Hg in IL/% 3 Hg(0) 0.00202 34.9 0.0000069 Initial charge of Hg 4 HgCl.sub.2 8115 42.75 18.5 5 HgO 1696 13.25 4.8 6 Hg(0) 7833 946.7 21.2 Second charge of Hg 4 HgCl.sub.2 12784 96.75 29.2 5 HgO 3958 69.95 11.1 Second charge of IL 6 Hg(0) 7738 65.55 15.9 [Hg] refers to mercury concentration C.sub.12 refers to dodecane

Example 7: Extraction of Elemental Mercury by Copper-Containing Choline Chloride/Ethylene Glycol Eutectic Fluid

(17) A mixture of choline chloride (30 g) and ethylene glycol (60 g) was prepared by mixing and heating to 50 C. to ensure the choline chloride was thoroughly dissolved following the procedure described by Abbott et al., PCCP 2009, 11, 4269. Copper chloride dihydrate (1.3 g, 7.6 mmol) was then added to the choline chloride/ethylene glycol eutectic (4.76 g, 11.4 mmol) to give a dark green-black fluid.

(18) Elemental mercury (0.35 g) was added to a sample of the eutectic fluid (0.85 g) and heated overnight at 60 C. A large volume of pale green precipitate was formed. A sample of 0.17 g of the liquid was diluted with 5 cm.sup.3 of deionised water giving a pale green solution and white precipitate. The solution was filtered and diluted to 50 cm.sup.3, and 1 cm.sup.3 of the diluted solution was further diluted to 50 cm.sup.3 with deionised water. The resulting solution was analysed for mercury using a Milestone DMA-80 direct mercury analyser. It was found that the eutectic fluid contained 16.9 wt % water soluble mercury species, based on the original eutectic mixture.

Example 8: Extraction of Elemental Mercury by Ionic Liquids Containing Different Metallate Anions

(19) This example examines the effectiveness of ionic liquids containing different metallate anions in the extraction of bulk elemental mercury. A sample of each ionic liquid was contacted with bulk elemental mercury, and stirred at 60 C. overnight, and a small sample of the resultant ionic liquid extracted into water and analysed for soluble mercury according to the procedure described in Example 1. The ionic liquids used and the results obtained are shown in Table 2.

(20) TABLE-US-00002 TABLE 2 Mass percent Ionic Liquid/Metal Salt [Hg] in IL after mercury (molar ratio IL/metal salt) contacting/ppm dissolved in IL [C.sub.2mim][Cl]/CuCl.sub.2 (2:1) 212604 21.3 [N.sub.4,4,4,1][Cl]/CuCl.sub.2 (2:1) 158917 15.9 [C.sub.2mim][Cl]/CuCl.sub.22H.sub.2O (2:1) 255241 25.5 [N.sub.4,4,4,1][Cl]/CuCl.sub.22H.sub.2O (2:1) 151753 15.2 [C.sub.4mim][Br]/CuBr.sub.2 (2:1) 30542 3.1

Example 9: Extraction of Elemental Mercury by Supported Ionic Liquids

(21) This example demonstrates the effect of different cations on the extraction of elemental mercury from natural gas condensate. (from PETRONAS Onshore Gas Terminal, Kerteh, Malaysia)

(22) A series of ionic liquids was formed using a 2:1 molar ratio of [Q][Cl] ionic liquid and CuCl.sub.2 (where [Q] represents the ionic liquid cation). Davisil SP540 powdered silica was impregnated with each of the ionic liquids to obtain supported ionic liquids containing 1 wt % Cu(II) (ca. 7.5 to 17 wt % IL depending on cation). The solid supported ionic liquid was compressed to a wafer and contacted with a stirred reservoir of mercury-containing condensate for three hours. A comparison using silica without ionic liquid is also provided. The results are shown in Table 3.

(23) TABLE-US-00003 TABLE 3 Starting in Final Mass Hg in [Hg] in Final [Hg] [Hg] in Mass IL condensate/ condensate/ wafer/ IL*/ [Q] in wafer/g ng ppm ppm ppm [C.sub.4mim] 0.0032 1455 455 361 4750 [P.sub.66614] 0.0032 1228 383 289 1562 [N.sub.4441] 0.0053 1600 301 207 2070 Silica 0.0055 521 94 0 0 *Exclusive of solid support

Example 10: Extraction of Elemental Mercury by Supported Ionic Liquids

(24) This example demonstrates the effect of different cations on the extraction of elemental mercury from hexane.

(25) A series of chlorometallate ionic liquids was formed from ionic liquids of the formula [Cat.sup.+][Cl] and CuCl.sub.2 at different molar ratios. The ionic liquids were impregnated into porous silica beads (Johnson Matthey, 2-4 mm diameter, 122 m.sup.2/g surface area) and contacted with hexane in the presence of a reservoir of elemental mercury in a stirred tank reactor for a period of 18 days. The composition of the solid supported IL and was determined for each IL after 6 days, 13 days and 18 days, and the results are shown in Table 4.

(26) TABLE-US-00004 TABLE 4 [Hg] [Hg] Hg Theoretical in solution/ in bead/ in bead/ Hg capacity Progress to IL Day ppm ppm wt % of IL saturation [P.sub.66614]Cl:CuCl.sub.2 6 0.7227 651 0.07 0.84972 7.66% 2:1 13 1.9375 1120 0.11 0.84972 13.18% 18 2.5043 2003 0.20 0.84972 23.58% [C.sub.4mim]Cl:CuCl.sub.2 6 3.3750 2446 0.24 2.06137 11.86% 2:1 13 6.2767 5062 0.51 2.06137 24.56% 18 6.9473 5838 0.58 2.06137 28.32% [C.sub.4mim]Cl:CuCl.sub.2 6 2.5714 1773 0.18 3.23525 5.48% 1:1 13 4.9129 3388 0.34 3.23525 10.47% 18 9.2259 6363 0.64 3.23525 19.67% [N.sub.4441]Cl:CuCl.sub.2 6 2.7097 2203 0.22 1.65224 13.33% 2:1 13 6.0009 2927 0.29 1.65224 17.72% 18 6.3139 6577 0.66 1.65224 39.81% [N.sub.4441]Cl:CuCl.sub.2 6 3.0407 2534 0.25 2.70653 9.36% 1:1 13 6.3527 3208 0.32 2.70653 11.85% 18 7.8380 5559 0.56 2.70653 20.54% [N.sub.4441]Cl:CuCl.sub.2 6 3.2485 1511 0.15 8.20161 1.84% 30% load 13 4.9564 1967 0.20 8.20161 2.40% 1:1 18 9.6332 8164 0.82 8.20161 9.95%

Example 11: Extraction of Elemental Mercury by Supported Ionic Liquids

(27) This example demonstrates the competitive extraction of mercury from hexane to ionic liquids and non-ionic liquid salts impregnated into silica spheres (Johnson Matthey, 1.7-4 mm diameter, 135 m.sup.2.Math.g.sup.1 surface area) and Calgon AP4-60 activated carbons. Reaction conditions are as in Example 10. The data in Table 5 shows that the silica supported material gave greater uptake of mercury compared to activated carbon supported materials under competitive extraction conditions.

(28) TABLE-US-00005 TABLE 5 [Hg] in Hg in [Hg] in Hg in bead/ bead/ Error bead/ bead/ Error Ionic liquid ppm wt % (%) ppm wt % (%) and support After 3 days After 8 days [bmim]Cl/CuCl.sub.2 857 0.086% 0 3560 0.3560 0 (1:1 on Silica spheres) [bmim]Cl/CuCl.sub.2 535 0.054% 5 882 0.0882% 3 (1:1 on AP4-60) choline:EG/CuCl.sub.2 400 0.040% 3 788 0.0788% 27 (1:1 on AP4-60) choline:EG/CuCl.sub.2 217 0.022% 69 1024 0.1024% 18 (2:1 on AP4-60) [bmim]Cl/CuCl.sub.2 110 0.011% 11 950 0.0950% 26 (2:1 on AP4-60) [N.sub.4,4,4,1]Cl/CuCl.sub.2 502 0.050% 27 966 0.0966% 15 (2:1 on AP4-60)

Example 12: Extraction of Elemental Mercury by Ionic Liquid Salts and Non-Ionic Liquid Metallate Salts

(29) This example demonstrates the extraction of mercury from hexane to ionic liquids and non-ionic liquid metallate salts impregnated into silica beads with a size range of either 0.7 to 1.4 or 1.7 to 4.0 mm diameter (ex Johnson Matthey). Reaction conditions are as in Example 11. The data is shown in Table 6.

(30) TABLE-US-00006 TABLE 6 [Hg] in Hg in [Hg] in Hg in bead/ bead/ Error bead/ bead/ Error Ionic liquid ppm wt % (%) ppm wt % (%) and support After 3 days After 8 days [N.sub.444H]Cl/CuCl.sub.2 3311 0.331 15 14324 1.43242 0.63 1:1 10% on Si#5 [N.sub.444H]Cl/CuCl.sub.2 5092 0.509 5 14128 1.41277 0.90 1:1 20% on Si#5 [N.sub.444H]Cl/CuCl.sub.2 6407 0.640 0.7 14298 1.42978 0.19 1:1 30% in Si#5 [N.sub.4441]Cl/CuCl.sub.2 1919 0.192 21 7680 0.76802 1.87 1:1 10% on Si#5 [N.sub.4441]Cl/CuCl.sub.2 4725 0.472 18499 1.84986 2.13 1:1 20% on Si#5 [N.sub.4441]Cl/CuCl.sub.2 9713 0.971 53 14834 1.4834 0.18 1:1 30% on Si#5 [N.sub.4441]Cl/CuCl.sub.2 7743 0.774 22 26112 2.61119 0.25 1:1 10% on Si#1 [N.sub.4441]Cl/CuCl.sub.2 10273 1.027 4 27432 2.74316 4.62 1:1 10% on Si#2 [N.sub.4441]Cl/CuCl.sub.2 12936 1.294 36 26073 2.60728 0.16 1:1 10% on Si#4 [N.sub.4441].sub.2MoS.sub.4 298 0.030 4 3971 0.39705 4.51 on Si#5 [P.sub.66614].sub.2MoS.sub.4 642 0.064 4 2927 0.29272 8.81 on Si#5 [NH.sub.4].sub.2MoS.sub.4 61 0.061 15 5076 0.50763 7.83 on Si#5

Example 13: Comparison of Extractive Capacity of Solid-Supported Ionic Liquids Having Metallate Anions, Non-Ionic Liquid Solid-Supported Metallate Salts, and Non-Metallate Salts

(31) This example provides a comparison of the extractive capacities of silica beads impregnated with CuCl.sub.2, LiCl/CuCl.sub.2 (1:1, forming the metallate anion Cu.sub.2Cl.sub.6.sup.2), and [N.sub.4,4,4,1]Cl/CuCl.sub.2 (1:1, also forming the metallate anion Cu.sub.2Cl.sub.6.sup.2). The data in FIG. 1 shows a clear improvement in extraction with salts containing metallate anions, and a further improvement when an ionic liquid is used.

Example 14: Liquid-IL Extraction of Total Mercury from Condensate using [C4mim]Cl/CuCl2.2H2O (2:1)

(32) The ionic liquid composition, [C.sub.4mim]Cl/CuCl.sub.2.2H.sub.2O (2:1), was prepared by direct combination, with warming, of the two components, 1-butyl-3-methylimidazolium chloride and copper(II)chloride dihydrate. Natural gas condensate was contacted with the ionic liquid at 50:1 condensate:IL mass ratio, stirred at room temperature and the upper bulk condensate phase periodically sampled for direct mercury analysis using a Milestone DMA-80 mercury analyser.

(33) The results are shown in Table 7, and demonstrate that after 60 min, approximately 75% of the total mercury in the sample had been removed, and after 1 day, the mercury content had been reduced to less than 3 ppb.

(34) TABLE-US-00007 TABLE 7 Mercury concentration in Time/min condensate/g kg.sup.1 (ppb) 0 96.95 20 62.47 40 36.84 60 25.63 1440 2.58

Example 15: Scrubbing of Mercury from a Gas by Supported Ionic Liquids

(35) Extraction of mercury from gas streams was demonstrated by passing a mercury-containing gas stream (mercury concentration 20-30 mg/m.sup.3, flow-rate 60 ml/min.) through a pipe reactor ( ss tube of thickness 0.035) containing 0.1 g, ca 0.2 cm.sup.3 of supported ionic liquid (bed length ca 1.2 cm). The mercury content at the reactor outlet was measured periodically by withdrawing gas samples and analysing using a PSA Sir Galahad mercury analyser. The detection limit for measurements was 2 g/m.sup.3.

(36) Results from tests with ionic liquids supported on activated carbon and porous silicas are shown in Table 8 and graphically in FIG. 2, compared to a comparative experiment with a commercial sulfur-impregnated activated carbon, and demonstrate that all four supported ionic liquids were more effective than the commercial sulfur-impregnated activated carbon at removing mercury.

(37) TABLE-US-00008 TABLE 8 Time to Mercury Percentage detect concentration mercury mercury measured at loading on at outlet breakthrough extractant at Composition (h) (g/m.sup.3) breakthrough Sample 1 [C.sub.4mim]Cl/CuCl.sub.2 1:1 10 wt 27 110 2.43 % impregnated into Calgon AP4-60 activated carbon Sample 2 [N.sub.4441]Cl/CuCl.sub.2 1:1 12 wt % 22 13 1.98 impregnated into Calgon AP4-60 Sample 3 [C.sub.4mim]Cl/CuCl.sub.2 1:1 10 wt 34 7 3.06 % impregnated into porous silica (Johnson Matthey, SA 135 m.sup.2/g, PV 0.85 cm.sup.3/mL) Sample 4 [C.sub.4mim]Cl/CuCl.sub.2 1:1 10 wt 37 11 3.33 % impregnated into porous granular silica (Grace Davison Davicat SI1157) Sample 5 Comparative test with 18 97 1.62 commercial sulfur- impregnated activated carbon (Chemviron Carbon, Calgon-HGR)