Catalyst composition for selective hydrogenation with improved characteristics

Abstract

This invention relates to heterogeneous catalysts useful for selective hydrogenation of unsaturated hydrocarbons, comprising palladium and optionally a promoter, supported on a substrate, having an uncoated BET surface area of 9 m.sup.2/g, the surface being coated with an ionic liquid. Also described are methods of making the catalysts and methods of selective hydrogenation of acetylene and/or dienes in front-end mixed olefin feed streams.

Claims

1. A method of selective hydrogenation of acetylene in front-end mixed olefin feed streams, comprising catalyzing said hydrogenation with a heterogeneous shell catalyst, the heterogeneous catalyst comprising: (i) a porous solid substrate having an uncoated BET surface area of less than 9 m.sup.2/g and an internal pore volume of 0.007 to 0.04 ml/g; (ii) the porous solid substrate having a metal or metal-alloy shell comprising palladium and optionally at least one promoter, the metal or metal-alloy shell having a thickness of 100 m to 500 m; and (iii) the porous solid substrate also having a shell consisting of 0.1% to 5% by weight of the heterogeneous catalyst of one or more ionic liquids coated on a pore surface of the substrate having the internal pore volume in a quantity that is less than the internal pore volume, the ionic liquid shell having a thickness of 10 m to 2000 m, wherein a total quantity of the one or more ionic liquids used is between 0.01% to 5% by weight of the heterogeneous shell catalyst, wherein the one or more ionic liquids consist of one or more compounds of the formula:
[A].sub.n.sup.+[Y].sub.n.sup., wherein: n=1 or 2; [A].sub.n.sup.+ comprises an imidazolium cation of the formula (III) ##STR00010## wherein R, R.sup.1, and R.sup.2 are independently selected from the group consisting of hydrogen and linear or branched C.sub.1-C.sub.12-alkyl groups, or [A].sub.n.sup.+ is selected from the group consisting of 1-butyl-1-methylpyrrolidinium, 1-ethyl-3-methylpyridinium, ethyldimethyl-(2-methoxyethyl)-ammonium, tributylmethylammonium, tricyclohexyltetradecylphosphonium, and mixtures thereof; and [Y].sub.n.sup. is selected from the group consisting of bis(trifluoromethylsufonyl)imide, dicyanamide, ethylsulfate, methylphosphonate, methylsulfate, octylsulfate, tetracyanoborate, tetrafluoroborate, tricyanomethane, triflate, tris(pentafluoroethyl)trifluorophosphate, and mixtures thereof.

2. The method of claim 1, wherein the selective hydrogenation occurs in a gas phase.

3. The method of claim 1, wherein the selective hydrogenation occurs in a liquid phase.

4. The method of claim 1, wherein the BET surface area is 8 m.sup.2/g.

5. The method of claim 4, wherein the BET surface area is 6 m.sup.2/g.

6. The method of claim 1, wherein the palladium-supported heterogeneous catalyst further comprises a promoter selected from the group consisting of Ag, Au, Zn, Sn, Cd, Pb, Cu, Bi, K, Ga, and mixtures thereof.

7. The method of claim 6, wherein the promoter comprises Ag.

8. The method of claim 6, wherein the heterogeneous catalyst has a mass ratio of Pd:promoter of 1:5-3:1.

9. The method of claim 1, wherein the heterogeneous catalyst has a Pd loading of 10 to 1000 ppm.

10. The method of claim 1, wherein [A].sup.+ is selected from the group consisting of 1-butyl-1-methylpyrrolidinium, 1-butyl-2,3-dimethylimidazolium, 1-butyl-3-methylimidazolium, 1-ethyl-3-methylimidazolium, 1-ethyl-3-methylpyridinium, 1-methyl-3-octylimidazolium, ethyldimethyl-(2-methoxyethyl) ammonium, tributylmethylammonium, tricyclohexyltetradecylphosphonium, and mixtures thereof.

11. The method of claim 1, wherein the ionic liquid consists of one or more selected from the group consisting of 1-butyl-3-methylimidazolium triflate, 1-ethyl-3-methylpyridinium ethylsulfate, 1-butyl-1-methylpyrrolidinium triflate, 1-butyl-2,3-dimethylimidazolium triflate, 1-butyl-3-methylimidazolium tricyanomethane, 1-butyl-3-methylimidazolium methylsulfate, 1-butyl-3-methylimidazolium octylsulfate, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium ethylsulfate, 1-ethyl-3-methylimidazolium methylphosphonate, 1-ethyl-3-methylimidazolium triflate, 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsufonyl)imide, 1-butyl-1-methylpyrrolidinium tetracyanoborate, 1-butyl-1-methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate, 1-butyl-3-methylimidazolium bis(trifluoromethylsufonyl)imide, 1-ethyl-3-methylpyridinium bis(trifluoromethylsufonyl)imide, 1-ethyl-3-methylimidazolium tetracyanoborate, 1-ethyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate, 1-methyl-3-octylimidazolium triflate, ethyldimethyl-(2-methoxyethyl) ammonium tris(pentafluoroethyl)trifluorophosphate, tributylmethylammonium dicyanamide, tricyclohexyltetradecylphosphonium tris(pentafluoroethyl)trifluorophosphate, 1-ethyl-3-methylimidazolium bis(trifluoromethylsufonyl)imide, and mixtures thereof.

12. The method of claim 1, wherein the heterogeneous catalyst has an ionic liquid loading of 0.1% to 5% by weight.

13. The method of claim 12, wherein the heterogeneous catalyst has an ionic liquid loading of 0.2% to 3% by weight.

14. The method of claim 13, wherein the heterogeneous catalyst has an ionic liquid loading of 0.3% to 1.5% by weight.

15. The method of claim 1, wherein the heterogeneous catalyst has a cleanup temperature of less than 80 C. and an operating window of greater than 25 C. when tested with a simulated de-ethanizer feed containing 0.35 mol % acetylene, 20 mol % hydrogen, 0.02 mol % CO, 45 mol % ethylene, and balance methane being passed over a 25 ml catalyst bed at 500 psig (35.5 bar) in total pressure and 7000 h.sup.1 in Gas Hourly Space Velocity (GHSV), while the bed temperature is increased from about 35 C., the clean up temperature is defined as the temperature at which the outlet reaches <25 ppm acetylene, the runaway temperature is defined as the temperature at which the outlet ethane concentration is >2% and the operation window is defined as the difference between the runaway temperature and the clean up temperature.

16. The method of claim 1, wherein the heterogeneous catalyst has the internal pore volume without the presence of the at least one ionic liquid in the range of 0.009 to 0.02 ml/g.

17. The method of claim 16, wherein the internal pore volume of the heterogeneous catalyst without the presence of said at least one ionic liquid is within a range of 0.007 to 0.04 ml/g.

18. The method of claim 17, wherein the internal pore volume of the heterogeneous catalyst without the presence of said at least one ionic liquid is within a range of 0.009 to 0.02 ml/g.

19. The method of claim 1, wherein the heterogeneous catalyst has a selectivity of >25% at clean up temperature, when tested with a simulated de-ethanizer feed containing 0.35 mol % acetylene, 20 mol % hydrogen, 0.02 mol % CO, 45 mol % ethylene, and balance methane being passed over a 25 ml catalyst bed at 500 psig (35.5 bar) in total pressure and 7000 h.sup.1 in Gas Hourly Space Velocity (GHSV), while the bed temperature is increased from about 35 C., the clean up temperature being defined as the temperature at which the outlet reaches <25 ppm acetylene.

20. The method of claim 1, wherein the one or more ionic liquids coated on the pore surface have a volume smaller than the internal pore volume of the catalyst and is provided via use of a quantity of the one or more ionic liquids that is less than the internal pore volume.

21. The method of claim 1, wherein the one or more ionic liquids are deposited such that a body of the heterogenous shell catalyst is externally dry.

Description

DETAILED DESCRIPTION OF THE INVENTION

(1) The pre-formulated catalysts used for coating are, as already described above, supported palladium shell catalysts which preferably comprise at least one further promoter such as for example silver, gold, zinc, tin, lead, gallium, cadmium, copper, bismuth, or potassium. Preferred promoters are Ag, Au and Zn. Preferred metal or metal-alloy shell thicknesses are between 100 and 500 m. The Pd metal content in relation to the total weight of the catalyst is between 10 and 1000 ppm, preferably between 50 and 500 ppm. For the desired target reaction the catalysts are used either as shaped bodies such as for example tablets, rings, tri-holes, extrudates etc., or as a granulate or powder. The mass ratio of palladium to promoter metal for example lies within a range of 1:5 to 3:1, preferably within a range of 1:4 to 2:1, and particularly preferably within a range of 1:1.

(2) Suitable carrier substrates are Al.sub.2O.sub.3, SiO.sub.2, alumo silicates, TiO.sub.2, ZrO.sub.2, ZnO, MgO, Fe.sub.2O.sub.3 and CeO.sub.2, or mixtures thereof. In order to increase activity or selectivity the substrates can further be doped with at least one of the following elements: Li, Na, K, Rb, Cs, Be, Mg, Ca, Sr and/or Ba. Na, K and/or Ca are particularly suitable.

(3) The BET surface area of the uncoated catalyst is 9 m.sup.2/g, and more preferably 8 m.sup.2/g, particularly preferably 6 m.sup.2/g. The determination of the surface area may be carried out in accordance with ASTM D3663, Standard Test Method for Surface Area of Catalysts and Catalyst Carriers.

(4) The integral pore volume of the catalyst (determined according to DIN 66134 of February 1998 (N, adsorption)) without the IL-coating preferably is in the range of 0.005 to 0.07 ml/g, more preferably in the range of 0.007 to 0.04 ml/g and particularly preferably within a range of 0.009 to 0.02 ml/g.

(5) Suitable pre-formulated catalysts for use in preparing supported ionic liquid phase catalyst compositions of the invention include any commercially-available supported Pd or Pd/Ag catalysts supplied by, for example Sd-Chemie, AG, Munich, Germany, BASF, Johnson-Mathey, etc.

(6) For the production of a catalyst composition of the invention a pre-formulated catalyst is loaded with ionic liquid. The ionic liquid to be used for this is not particularly restricted, and in principle, all known ionic liquids suitable for this purpose can be used. Preferred ionic liquids for use with this invention are compounds with the formula (I):
[A].sub.n.sup.+[Y].sub.n.sup.(I),

(7) wherein:

(8) n=1 or 2;

(9) [Y].sub.n.sup.+ is selected from the group consisting of tetrafluoroborate ([BF.sub.4].sup.), hexafluorophosphate ([PF.sub.6].sup.), dicyanamide ([N(CN).sub.2].sup.), halides (Cl.sup., Br.sup., F.sup., I.sup.), hexafluoroantimonate ([SbF.sub.6].sup.), nitrate ([NO.sub.3].sup.), nitrite ([NO.sub.2].sup.), anionic metal complexes such as for example [CuCl.sub.4].sup.2, [PdCl.sub.4].sup.2 or [AuCl.sub.4].sup., acetate ([CH.sub.3COO].sup.), trifluoracetate ([F.sub.3CCOO].sup., hexafluoroarsenate ([AsF.sub.6].sup.), sulfate ([SO.sub.4].sub.2.sup.), alkyl sulfates ([RSO.sub.4].sup.), tosylate ([C.sub.7H.sub.7SO.sub.3].sup.), triflate ([CF.sub.3SO.sub.3].sup.), nonaflate ([C.sub.4F.sub.9SO.sub.3].sup.), triperfluoroethylene trifluorophosphate ([PF.sub.3(C.sub.2F.sub.5).sub.3].sup.), tricyanomethide ([C(CN).sub.3].sup.), tetracyanoborate ([B(CN).sub.4].sup., thiocyanate ([SCN].sup.), carbonate ([CO.sub.3].sub.2.sup.), carboxylates ([RCOO].sup.), sulfonates ([RSO.sub.3].sup.), dialkyiphosphates ([RPO.sub.4R].sup.), alkyl phosphonates ([RHPO.sub.3].sup.) and bissulfonylimides ([(RSO.sub.2).sub.2N].sup.), such as bis(trifluormethylsulfonyl)imide,

(10) wherein R and R are the same or different, and each represents a linear or branched, 1 to 12 carbon atom-containing aliphatic or alicyclic alkyl group or a C.sub.5-C.sub.18-aryl, C.sub.5-C.sub.18-aryl-C.sub.1-C.sub.6-alkyl, or C.sub.1-C.sub.6-alkyl-C.sub.5-C.sub.18-aryl group that can be substituted with halogen atoms; and

(11) [A].sup.+ is selected from the group consisting of quaternary ammonium cations with the formula [NR.sup.1R.sup.2R.sup.3R].sup.+, phosphonium cations with the formula [PR.sup.1R.sup.2R.sup.3R].sup.+, sulfonium cations with the formula [SR.sup.1R.sup.2R].sup.+, guadinium cations with the formula (II):

(12) ##STR00001##

(13) imidazolium cations with the formula (III)

(14) ##STR00002##
wherein the imidazole core may additionally be substituted with one or more groups selected from C.sub.1-C.sub.6-alkyl, C.sub.1-C.sub.6-alkoxy, C.sub.1-C.sub.6-aminoalkyl, C.sub.5-C.sub.12-aryl, and C.sub.5-C.sub.12-aryl-C.sub.1-C.sub.6-alkyl groups,

(15) pyridinium cations with the formula (IV)

(16) ##STR00003##
wherein the pyridine core may additionally be substituted with one or more groups selected from C.sub.1-C.sub.6-alkyl, C.sub.1-C.sub.6-alkoxy, C.sub.1-C.sub.6-aminoalkyl, C.sub.5-C.sub.12-aryl, and C.sub.5-C.sub.12-aryl-C.sub.1-C.sub.6-alkyl groups,

(17) pyrazolium cations with the formula (V)

(18) ##STR00004##
wherein the pyrazole core may additionally be substituted with one or more groups selected from C.sub.1-C.sub.6-alkyl, C.sub.1-C.sub.6-alkoxy, C.sub.1-C.sub.6-aminoalkyl, C.sub.5-C.sub.12-aryl, and C.sub.5-C.sub.12-aryl-C.sub.1-C.sub.6-alkyl groups,

(19) triazolium cations h the formula (VI)

(20) ##STR00005##
wherein the triazole core may additionally be substituted with one or more groups selected from C.sub.1-C.sub.6-alkyl, C.sub.1-C.sub.6-alkoxy, C.sub.1-C.sub.6-aminoalkyl, C.sub.5-C.sub.12-aryl, and C.sub.5-C.sub.12-aryl-C.sub.1-C.sub.6-alkyl groups,

(21) and pyrrolidinium cations with the formula (VII)

(22) ##STR00006##
wherein the pyrrolidinium core may additionally be substituted with one or more groups selected from C.sub.1-C.sub.6-alkyl, C.sub.1-C.sub.6-alkoxy, C.sub.1-C.sub.6-aminoalkyl, C.sub.5-C.sub.12-aryl, and C.sub.5-C.sub.12-aryl-C.sub.1-C.sub.6-alkyl groups,

(23) wherein R.sup.1, R.sup.2, and R.sup.3 are selected independently from each other from the group consisting of: hydrogen; linear or branched, saturated or unsaturated, aliphatic or alicyclic alkyl groups with 1 to 20 carbon atoms, which may be interrupted by one or two of NH, O and/or S; heteroaryl groups with 3 to 8 carbon atoms and at least one hetero atom selected from N, O and S, wherein the heteroaryl groups can be substituted with one or more groups selected from C.sub.1-C.sub.6-alkyl groups and halogen atoms; heteroaryl-C.sub.1-C.sub.6-alkyl groups with 3 to 8 carbon atoms and at least one hetero atom selected from N, O and S in the heteroaryl portion, wherein the heteroaryl portion can be substituted with at least one group selected from C.sub.1-C.sub.6-alkyl groups and halogen atoms; polyethers with the formula [CH.sub.2CH.sub.2O].sub.nR.sup.a with n=1 to 50,000, wherein R.sup.a is selected from the group consisting of linear or branched, saturated or unsaturated, aliphatic or alicyclic alkyl groups with 1 to 20 carbon atoms; aryl groups with 5 to 12 carbon atoms, which may be substituted with one or more C.sub.1-C.sub.6-alkyl groups and/or halogen atoms; aryl-C.sub.1-C.sub.6-alkyl groups with 5 to 12 carbon atoms in the aryl portion, which may be substituted with one or more C.sub.1-C.sub.6-alkyl groups and/or halogen atoms, and

(24) wherein R is selected from the group consisting of: linear or branched, saturated or unsaturated, aliphatic or alicyclic alkyl groups with 1 to 20 carbon atoms; heteroaryl-C.sub.1-C.sub.6 alkyl groups with 4 to 8 carbon atoms and at least one hetero atom selected from N, O and S in the heteroaryl portion, which may be substituted with one or more C.sub.1-C.sub.6-alkyl groups and/or halogen atoms; and aryl-C.sub.1-C.sub.6-alkyl groups with 4 to 12 carbon atoms in the aryl portion, which may be substituted with one or more C.sub.1-C.sub.6-alkyl groups and/or halogen atoms.

(25) Further preferred ionic liquids for use with this invention are compounds with the formula (I):
[A].sub.n.sup.+[Y].sub.n.sup.(I),
wherein:

(26) n and [Y].sub.n.sup. are as defined above, and

(27) [A].sup.+ is selected from the group consisting of quaternary ammonium cations with the formula [NR.sup.1R.sup.2R.sup.3R].sup.+, imidazolium cations with the formula (III)

(28) ##STR00007##
pyridinium cations with or formula (IV)

(29) ##STR00008##
and pyrrolidinium cations with the formula (VII)

(30) ##STR00009##

(31) wherein R, R.sup.1, R.sup.2 and R.sup.3 are selected independently from each other from the group consisting of hydrogen; linear or branched C.sub.1-C.sub.12-alkyl groups; linear or branched (C.sub.1-C.sub.6-alkyloxy)-C.sub.1-C.sub.6-alkyl groups; and aryl-C.sub.1-C.sub.6-alkyl groups with 5 to 12 carbon atoms in the aryl portion, which may be substituted with one or more C.sub.1-C.sub.6-alkyl groups and/or halogen atoms

(32) More preferred ionic liquids for preparing supported ionic liquid phase catalysts of the invention include 1-butyl-3-methylimidazolium triflate, 1-ethyl-3-methylpyridinium ethylsulfate, 1-butyl-1-methylpyrrolidinium triflate, 1-butyl-2,3-dimethylimidazolium triflate, 1-butyl-3-methylimidazolium tricyanomethane, 1-butyl-3-methylimidazolium methylsulfate, 1-butyl-3-methylimidazolium octylsulfate, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium ethylsulfate, 1-ethyl-3-methylimidazolium methylphosphonate, 1-ethyl-3-methylimidazolium triflate, 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsufonyl)imide, 1-butyl-1-methylpyrrolidinium tetracyanoborate, 1-butyl-1-methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate, 1-butyl-3-methylimidazolium bis(trifluoromethylsufonyl)imide, 1-butyl-3-methylimidazolium tricyanomethane, 1-ethyl-3-methylpyridinium bis(trifluoromethylsufonyl)imide, 1-ethyl-3-methylimidazolium tetracyanoborate, 1-ethyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate, 1-ethyl-3-methytpyridinium bis(trifluoromethylsufonyl)imide, 1-methyl-3-octylimidazolium trifiate, ethyldimethyl-(2-methoxyethyl)ammonium tris(pentafluoroethyl)trifluorophosphate, tributylmethylammonium dicyanamide, tricyclohexyltetradecylphosphonium tris(pentafluoroethyl)trifluorophosphate, 1-ethyl-3-methylimidazolium bis(trifluoromethylsufonyl)imide, and mixtures thereof.

(33) More preferred ionic liquids further include those of the formula (I), wherein [A].sub.n.sup.+ is selected from the group consisting of 1-butyl-1-methylpyrrolidinium, 1-butyl-2,3-dimethylimidazolium, 1-butyl-3-methylimidazolium, 1-ethyl-3-methylimidazolium, 1-ethyl 3-methylpyridinium, 1-methyl-3-octylimiciazolium, ethyldimethyl-(2-methoxyethyl)ammonium, tributylmethylammonium, tricyclohexyltetradecylphosphonium, and mixtures thereof, and wherein [Y].sub.n.sup. is selected from the group consisting of bis(trifluoromethylsufonypimide, dicyanamide, ethylsulfate, methylphosphonate, methylsulfate, octylsulfate, tetracyanohorate, tetrafluoroborate, tricyanomethane, Vitiate, tris(pentafluoroethyl)trifiuorophosphate, and mixtures thereof.

(34) For the production of catalyst compositions of the invention, the ionic liquid or mixtures of several ionic liquids are dissolved or suspended in a solution agent suitable for the purpose, such as for example water, alcohols, acetone etc., or in a solution agent mixture, and applied continuously onto the already pre-formed catalyst inside a reaction chamber with the aid of a nozzle. For this the solution agent Is continuously removed from the reaction chamber during the process. In order to achieve an even coating of the substrate, the substrate material is continuously fluidized through a process gas in a process known as fluidized bed coating. Further suitable coating processes are dip coating or spray application with a spray pistol or a spray drying pistol.

(35) Apart from the application of ionic liquid by means of coating technologies, the same can also be applied by impregnating with a solution or suspension. For this the ionic liquid or mixtures of several ionic liquids are dissolved or suspended in a suitable solution agent (mixture) and subsequently brought into contact with the pre-formed catalyst. The solution agent is then removed under vacuum or at an increased temperature (or both), by resting in air, or by means of a gas stream. The quantity of solution agent used can be equal to or smaller or greater than the pore volume of the catalyst used.

(36) The quantity of ionic liquid used is equal to or smaller than the pore volume of the catalyst used. After the application of the ionic liquid, one is left with an externally dry solid body coated with the desired quantity of ionic liquid. The pore volume of the resulting catalyst composition is reduced by the volume of the ionic liquid. Related to the total weight of the catalyst 0.01-10%, preferably 0.1-5 wt. %, more preferably 0.2-3 wt. %, and particularly preferably 0.3-1.5 wt. % of ionic liquid is used. The distribution of ionic liquid on the macroscopic substrate form body, granulate or powder is freely adjustable by selecting the coating conditions. Depending on the selection of the conditions, a formation of a so-called eggshell, egg-white, egg-yolk, or a uniform distribution of the ionic liquid may result on the substrate. In addition, any concentration gradient of ionic liquid can be created on the substrate. The ionic liquid is preferably applied to the substrate surface as a thin shell. The shell thickness of the ionic liquid on the substrate surface of this invention usually lies within a range of 10 to 2000 m, preferably within a range of 20 to 1000 m, and particularly preferably within a range of 50 to 250 m.

(37) The resulting catalyst can be used without restricting the target reaction. The reduction of metal particles required for activating the catalyst can either take place prior to a coating with the ionic liquid or following the same.

(38) The catalyst can for example be reduced prior to coating with an Ionic liquid. The methods to be used for the same are known to the expert, and can for example include wet chemical methods through reduction such as for example NaBH.sub.4, LiAlH.sub.4, hydrazine (hydrate), hypophosphite, formic acid, or salts of the same (formates). In addition a reduction can be brought about in the gaseous phase with hydrogen (in all mixtures with an inert gas; preferably 5% in N.sub.2) within a temperature range of 50-200 C., preferably at 80-120 C.

(39) The reduced metal particles obtained in this way usually have a diameter within a range of 1 to 30 nm, preferably within a range of 1 to 10 nm, and particularly preferably within a range of 2 to 8 nm.

EXAMPLES

Example 1

(40) Sample A contains 0.017 wt % Pd on 1-2 mm alumina spheres with a BET surface area of 4.0 m.sup.2/g. In order to make Sample A, 1100 g Alpha Alumina was added to 1075 mL PdCl.sub.2 solution (0.178 mg Pd/mL) heated at 70 C. After the carrier was soaked in the solution for 1 hour, the solution was drained and then the catalyst was washed 10 times using 5 minute soak times with room temperature deionized water. After final wash, the catalyst was calcined in a muffle oven in air at 565 C. for 4 hours.

(41) Sample A1 was made by adding 0.5 wt % of EMIM[EtSO.sub.4] (1-ethyl-3-methylimidazolium ethylsulfate) on Sample A. In order to make Sample A1, Sample A (516.0 mg) was impregnated with an aqueous solution of 1-ethyl-3-methylimidazolium ethylsulfate (232 L, 11.11 mg/mL) by incipient wetness. The catalyst was dried at 80 C. for 16 hours and reduced at 100 C. in 5% H.sub.2/N.sub.2 for 1 hour.

(42) Sample A2 was made by adding 0.5 wt % of BMIM[OTf] (1-butyl-3-methylimidazolium triflate) on Sample A. In order to make Sample A2, Sample A (476.3 mg) was impregnated with an aqueous solution of 1-butyl-3-methylimidazolium triflate (214 L, 11.11 mg/mL) by incipient wetness. The catalyst was dried at 80 C. for 16 hours and reduced at 100 C. In 5% H.sub.2/N.sub.2 for 1 hour.

(43) Sample A3 was made by adding 0.5 wt % of BMPr[OTf] (1-butyl-1-methylpyrrolidinium triflate) on Sample A. In order to make Sample A3, Sample A (499.7 mg) was impregnated with an aqueous solution of 1-butyl-1-methylpyrrolidinium triflate (225 L, 11.11 mg/mL) by incipient wetness. The catalyst was dried at 80 C. for 16 hours and reduced at 100 C. in 5% H.sub.2/N.sub.2 for 1 hour.

(44) Sample A4 was made by adding 0.5 wt % of BMMIM[OTf] (1-Butyl-2,3-dimethylimidazolium triflate) on Sample A. In order to make Sample A4, Sample A (528.8 mg) was impregnated with an aqueous solution of 1-Butyl-2,3-dimethylimidazolium triflate (238 L, 11.11 mg/mL) by incipient wetness. The catalyst was dried at 80 C. for 16 hours and reduced at 100 C. in 5% H.sub.2/N.sub.2 for 1 hour.

(45) Sample A5 was made by adding 0.5 wt % of BMIM[BF.sub.4] (1-butyl-3-methylimidazolium tetrafluoroborate) on Sample A. In order to make Sample A5, Sample A (508.2 mg) was impregnated with an aqueous solution of 1-butyl-3-methylimidazolium tetrafluoroborate (229 L, 11.11 mg/mL) by incipient wetness. The catalyst was dried at 80 C. for. 16 hours and reduced at 100 C. in 5% H.sub.2/N.sub.2 for 1 hour.

(46) Sample A6 was made by adding 0.5 wt % of BMIM[MeSO.sub.4] (1-butyl-3-methylimidazolium methylsulfate) on Sample A. In order to make Sample A6, Sample A (511.5 mg) was impregnated with an aqueous solution of 1-butyl-3-methylimidazolium methylsulfate (230 L, 11.11 mg/mL) by incipient wetness. The catalyst was dried at 80 C. for 16 hours and reduced at 100 C. in 5% H.sub.2/N.sub.2 for 1 hour,

(47) Sample A7 was made by adding 0.5 wt % of BMIM[C.sub.8H.sub.17SO.sub.4] (1-butyl-3-methylimidazolium octylsulfate) on Sample A. In order to make Sample A7, Sample A (485.7 mg) was impregnated with an aqueous solution of 1-butyl-3-methylimidazolium octylsulfate (218 L, 11.11 mg/mL) by incipient wetness. The catalyst was dried at 80 C. for 16 hours and reduced at 100 C. in 5% H.sub.2/N.sub.2 for 1 hour.

(48) Sample A8 was made by adding 0.5 wt % of EMIM[OTf] (1-ethyl-3-methylimidazolium triflate) on Sample A. In order to make Sample A8, Sample A (509.9 mg) was impregnated with an aqueous solution of 1-ethyl-3-methylimidazolium triflate (229 L, 11.11 mg/mL) by incipient wetness. The catalyst was dried at 80 C. for 16 hours and reduced at 100 C. in 5% H.sub.2/N.sub.2 for 1 hour.

(49) Sample A9 was made by adding 0.5 wt % of EMPy[EtSO.sub.4] (1-ethyl-3-methylpyridinium ethylsulfate) on Sample A. In order to make Sample A9, Sample A (504.0 mg) was impregnated with an aqueous solution of 1-ethyl-3-methylpyridinium ethylsulfate (227 L 11.11 mg/mL) by incipient wetness. The catalyst was dried at 80 C. for 16 hours and reduced at 100 C. in 5% H.sub.2/N.sub.2 for 1 hour.

(50) Sample A10 was made by adding 0.5 wt % of EMIM[MePO.sub.3] (1-ethyl-3-methylimidazolium methylphosphonate) on Sample A. In order to make Sample A10, Sample A (517.1 mg) was impregnated with an aqueous solution of 1-ethyl-3-methylimidazolium methylphosphonate (233 L, 11.11 mg/mL) by incipient wetness. The catalyst was dried at 80 C. for 16 hours and reduced at 100 C. in 5% H.sub.2/N.sub.2 for 1 hour.

(51) Sample A11 was made by adding 0.5 wt % of BMIM[C(CN).sub.3] (1-butyl-3-methylimidazolium tricyanomethane) on Sample A. In order to make Sample A11, Sample A (504.0 mg) was impregnated with a solution of 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide in 2-butanone (227 L, 11.11 mg/mL) by incipient wetness. The catalyst was dried at 60 C. for 4 hours and reduced at 100 C. in 5% H.sub.2/N.sub.2 for 1 hour.

(52) Sample A12 was made by adding 0.5 wt % of BMIM[NTf.sub.2] (1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) on Sample A. In order to make Sample A12, Sample A (513.4 mg) was impregnated with a solution of 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide in 2-butanone (231 L, 11.11 mg/mL) by incipient wetness. The catalyst was dried at 60 C. for 4 hours and reduced at 100 C. in 5% H.sub.2/N.sub.2 for 1 hour.

(53) Sample A13 was made by adding 0.5 wt % of MOIM[OTf] (1-methyl-3-octylimidazolium trifiate) on Sample A. In order to make Sample A13, Sample A (502.1 mg) was impregnated with a solution of 1-methyl-3-octylimidazolium triflate in 2-butanone (226 L, 11.11 mg/mL) by incipient wetness. The catalyst was dried at 60 C. for 4 hours and reduced at 100 C. in 5% H.sub.2/N.sub.2 for 1 hour.

(54) Sample A14 was made by adding 0.5 wt % of EMIM[NTf.sub.2] (1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) on Sample A. In order to make Sample A14, Sample A (490.3 mg) was impregnated with a solution of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide in 2-butanone (220 L, 11.11 mg/mL) by incipient wetness. The catalyst was dried at 60 C. for 4 hours and reduced at 100 C. in 5% H.sub.2/N.sub.2 for 1 hour.

(55) Sample A15 was made by adding 0.5 wt % of EMIM[B(CN).sub.4] (1-ethyl-3-methylimidazolium tetracyanoborate) on Sample A. In order to make Sample A15, Sample A (504.8 mg) was impregnated with a solution of 1-ethyl-3-methylimidazolium tetracyanoborate in 2-butanone (227 L, 11.11 mg/mL) by incipient wetness. The catalyst was dried at 60 C. for 4 hours and reduced at 100 C. in 5% H.sub.2/N.sub.2 for 1 hour.

(56) Sample A16 was made by adding 0.5 wt % of EMIM[PF.sub.3(C.sub.2F.sub.5).sub.3] (1-ethyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate) on Sample A. In order to make Sample A16, Sample A (514.4 mg) was impregnated with a solution of 1-ethyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate in 2-butanone (231 L, 11.11 mg/mL) by incipient wetness. The catalyst was dried at 60 C. for 4 hours and reduced at 100 C. in 5% H.sub.2/N.sub.2 for 1 hour.

(57) Sample A17 was made by adding 0.5 wt % of EMPy[NTf.sub.2] (1-ethyl-3-methylpyridinium bis(trifluoromethylsulfonypimide) on Sample A. In order to make Sample A17, Sample A (531.6 mg) was impregnated with a solution of 1-ethyl-3-methylpyridinium bis(trifluoromethylsulfonyl)imide in 2-butanone (239 L, 11.11 mg/mL) by Incipient wetness. The catalyst was dried at 60 C. for 4 hours and reduced at 100 C. in 5% H.sub.2/N.sub.2 for 1 hour.

(58) Sample A18 was made by adding 0.5 wt % of BMPr[NTf.sub.2] (1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide) on Sample A. In order to snake Sample A18, Sample A (512.5 mg) was impregnated with a solution of 1-butyl-1-methylpyrrolidinium bis(trifiuoromethylsulfonyl)imide in 2-butanone (230 L, 11.11 mg/mL) by incipient wetness. The catalyst was dried at 60 C. for 4 hours and reduced at 100 C. in 5% H.sub.2/N.sub.2 for 1 hour.

(59) Sample A19 was made by adding 0.5 wt % of BMPr[PF.sub.3(C.sub.2F.sub.5).sub.3] (1-butyl-1-methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate) on Sample A. In order to make Sample A19, Sample A (510.3 mg) was impregnated with a solution of 1-butyl-1-methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate in 2-butanone (229 L, 1 mg/mL) by incipient wetness. The catalyst was dried at 60 C. for 4 hours and reduced at 100 C. in 5% H.sub.2/N.sub.2 for 1 hour.

(60) Sample A20 was made by adding 0.5 wt % of BMPr[B(CN).sub.4] (1-butyl-1-methylpyrrolidinium tetracyanoborate) on Sample A. In order to make Sample A20, Sample A (516.0 mg) was impregnated with a solution of 1-butyl-1-methylpyrrolidinium tetracyanoborate in 2-butanone (232 L, 11.11 mg/mL) by incipient wetness. The catalyst was dried at 60 C. for 4 hours and reduced at 100 C. in 5% H.sub.2/N.sub.2 for 1 hour.

(61) Sample A21 was made by adding 0.5 wt % of TBMA[N(CN).sub.2] (tributylmethylammonium dicyanamide) on Sample A. In order to make Sample A21, Sample A (474.2 mg) was impregnated with a solution of tributylmethylammonium dicyanamide in 2-butanone (213 L, 11.11 mg/mL) by incipient wetness. The catalyst as dried at 60 C. for 4 hours and reduced at 100 C. in 5% H.sub.2/N.sub.2 for 1 hour.

(62) Sample A22 was made by adding 0.5 wt % of {EtMe.sub.2(MeOEt)}N[PF.sub.3(C.sub.2F.sub.5).sub.3] (ethyldimethyl-(2-methoxyethyl)ammonium tris(pentafluoroethyl)trifluorophosphate) on Sample A. In order to make Sample A22, Sample A (477.6 mg) was impregnated with a solution of ethyldimethyl-(2-methoxyethyl)ammonium tris(pentafluoroethyl)trifluorophosphate in 2-butanone (215 L, 11.11 mg/mL) by incipient wetness. The catalyst was dried at 60 C. for 4 hours and reduced at 100 C. in 5% H.sub.2/N.sub.2 for 1 hour.

Example 2

(63) Sample B1 was made by adding 0.001 wt % of EMIM[EtSO.sub.4] (1-ethyl-3-methylimidazolium ethylsulfate) on Sample A. In order to make Sample B1, Sample A (485.8 mg) was impregnated with an aqueous solution of 1-ethyl-3-methylimidazolium ethylsulfate (219 L, 0.022 mg/mL) by incipient wetness. The catalyst was dried at 80 C. for 16 hours and reduced at 100 C. in 5% H.sub.2/N.sub.2 for 1 hour.

(64) Sample B2 was made by adding 0.007 wt % of EMIM[EtSO.sub.4] (1-ethyl-3-methylimidazolium ethylsulfate) on Sample A. In order to make Sample B2, Sample A (505.1 mg) was impregnated with an aqueous solution of 1-ethyl-3-methytimidazolium ethylsulfate (227 L, 0.16 mg/mL) by incipient wetness. The catalyst was dried at 80 C. for 16 hours and reduced at 100 C. in 5% H.sub.2/N.sub.2 for 1 hour.

(65) Sample B3 was made by adding 0.025 wt % of EMIM[EtSO.sub.4] (1-ethyl-3-methylimidazolium ethylsulfate) on Sample A. In order to make Sample B3, Sample A (512.8 mg) was impregnated with an aqueous solution of 1-ethyl-3-methylimidazolium ethylsulfate (231 L, 0.56 mg/mL) by incipient wetness. The catalyst was dried at 80 C. for 16 hours and reduced at 100 C. in 5% H.sub.2/N.sub.2 for 1 hour.

(66) Sample B4 was made by adding 0.05 wt % of EMIM[EtSO.sub.4] (1-ethyl-3-methylimidazolium ethylsulfate) on Sample A. In order to make Sample B4, Sample A (468.0 mg) was impregnated with an aqueous solution of 1-ethyl-3-methylimidazolium ethylsulfate (210 L, 1.11 mg/mL) by Incipient wetness. The catalyst was dried at 80 C. for 16 hours and reduced at 100 C. in 5% H.sub.2/N.sub.2 for 1 hour.

(67) Sample B5 was made by adding 0.1 wt % of EMIM[EtSO.sub.4] (1-ethyl-3-methylimidazolium ethylsulfate) on Sample E. In order to make Sample B5, Sample A (497.3 mg) was impregnated with an aqueous solution of 1-ethyl-3-methylimidazolium ethylsulfate (224 L, 2.22 mg/mL) by incipient wetness. The catalyst was dried at 80 C. for 16 hours and reduced at 100 C. in 5% H.sub.2/N.sub.2 for 1 hour.

(68) Sample B6 was made by adding 0.25 wt % of EMIM[EtSO4] (1-ethyl-3-methylimidazolium ethylsulfate) on Sample A. In order to make Sample B6, Sample A (480.9 mg) was impregnated with an aqueous solution of 1-ethyl-3-methylimidazolium ethylsulfate (216 L, 5.56 mg/mL) by incipient wetness. The catalyst was dried at 80 C. for 16 hours and reduced at 100 C. in 5% H.sub.2/N.sub.2 for 1 hour.

Comparative Example 3

(69) Comparative Sample C contains 0.019 wt % Pd on 1-2 mm alumina spheres with a BET surface area of 50 m.sup.2/g. In order to make Comparative Sample C, 10 g alumina was added to 11.4 mL PdCl.sub.2 solution (0.1667 mg Pd/mL) heated at 70 C. After the carrier was soaked in the solution for 1 hour, the solution was withdrawn and then the catalyst was washed 10 times using 5 minute soak times with room temperature deionized water. After the final washing step, the catalyst was calcined in muffle oven in air at 565 C. for 4 hours.

(70) Comparative Sample C1 was made by adding 0.5 wt % of EMIM[EtSO.sub.4] (1-ethyl-3-methylimidazolium ethylsulfate) on Comparative Sample C. In order to make Comparative Sample C1, Comparative Sample C (502.1 mg) was impregnated with an aqueous solution of 1-ethyl-3-methylimidazolium ethylsulfate (316 L, 7.94 mg/mL) by incipient wetness. The catalyst was dried at 80 C. for 16 hours and reduced at 100 C. in 5% H.sub.2/N.sub.2 for 1 hour.

(71) Comparative Sample C2 was made by adding 0.5 wt % of BMIM[OTf] (1-butyl-3-methylimidazolium triflate) on Comparative Sample C. In order to make Comparative Sample C2, Comparative Sample C (484.4 mg) was impregnated with an aqueous solution of 1-butyl-3-methylimidazolium triflate (305 L, 7.94 mg/mL) by incipient wetness. The catalyst was dried at 80 C. for 16 hours and reduced at 100 C. in 5% H.sub.2/N.sub.2 for 1 hour.

Example 4

(72) Sample A, Samples A1-A22, Samples B1-B6, and Comparative Samples C, C1 and C2 were tested as prepared in a microreactor test unit at typical front-end hydrogenation conditions. In the test, a simulated de-propanizer feed containing 0.35 mol % acetylene, 15 mol % hydrogen, 0.02 mol % CO, 47 mol % ethylene, and balance nitrogen was passed over a 260 l catalyst bed at 478 psig (34 bar) in total pressure and 7000 h.sup.1 in Gas Hourly Space Velocity (GHSV), while the bed temperature was gradually increased from about 45 C. The acetylene concentration at the reactor outlet was monitored with an on-line gas chromatograph (GC). The acetylene concentration at reactor outlet continued decreasing with increasing temperature until reaching <25 ppm. The temperature at this point was defined as the clean up temperature (T1). Catalyst bed temperature was further increased until 125 C. (the maximum temperature the test unit could reach) or a certain temperature (T2), at which the outlet ethane concentration was >2% due to the increased non-selective reaction of hydrogen with ethylene. The temperature range between T1 and T2 is called the operation window. Test results of Sample A, Samples A1 to A22, Samples B1-B6, as well as of Comparative Sample C, C1-C2 are listed in the table below. For catalysts that did not run away at the maximum temperature the test unit could reach, T2 was calculated by fitting the data at temperatures above complete acetylene conversion with a first order kinetic model.

(73) TABLE-US-00001 Test Results of Samples A, A1 to A22, B1 to B6, and Comparative Samples C and C1 to C2 Operation T1 T2 Window Selectivity Ethane Make [ C.] [ C.] [ C.] at T1 [%] at 125 C. Sample A 63 84 21 92.8 10.439 Sample A1 68 176 108 96.1 0.429 Sample A2 68 137 69 96.9 0.714 Sample A3 61 113 52 89.0 3.316 Sample A4 62 113 51 85.6 3.228 Sample A5 69 164 95 94.5 0.462 Sample A6 68 167 99 97.6 0.390 Sample A7 68 157 89 95.5 0.594 Sample A8 65 141 76 96.2 1.139 Sample A9 65 100 35 95.8 9.45 Sample A10 82 188 106 90.1 0.194 Sample A11 68 157 89 90.0 0.637 Sample A12 61 100 39 89.5 4.668 Sample A13 67 115 48 66.1 3.005 Sample A14 60 110 50 99.8 3.477 Sample A15 71 149 78 90.6 0.821 Sample A16 67 145 78 90.1 1.199 Sample A17 62 86 24 93.0 10.23 Sample A18 64 101 37 88.9 4.836 Sample A19 62 120 58 74.8 2.382 Sample A20 69 150 81 98.9 0.906 Sample A21 65 153 88 85.2 0.982 Sample A22 66 122 56 93.2 2.315 Sample B1 62 82 20 47.3 10.444 Sample B2 63 101 38 69.0 8.691 Sample B3 60 113 53 96.3 9.122 Sample B4 61 119 58 95.5 5.378 Sample B5 65 121 56 98.4 3.838 Sample B6 67 123 56 100 2.428 Comparative Sample 56 76 20 91.1 10.506 C Comparative Sample 68 99 31 81.3 5.725 C1 Comparative Sample 65 98 33 96.1 6.878 C2
The operation window as well as the selectivity markedly increase with decrease in BET surface area (Samples A1 and A2 compared to Comparative Samples C1 and C2).

Example 5

(74) Sample D is a commercial selective hydrogenation catalyst that is supplied by Sd-Chemie AG under trade name OleMax 251. It contains 0.019 wt % Pd and 0.05 wt % Ag on 44 mm alumina tablets with a BET surface area of about 4.0 m.sup.2/g.

(75) Sample D1 was made by adding 0.5 wt % of BMMIM[OTf] (1-Butyl-2,3-dimethylimidazolium triflate) on Sample D. In order to make Sample D1, 0.6 g of the ionic liquid BMMIM[OTf] were dissolved in 150 ml deionized water. At the same time 120 g of the dry Sample D is fluidized in a reaction chamber with synthetic air as the process gas. The solution of BMMIM[OTf] in water was introduced into the reaction chamber at a flow rate of 5 ml/min via a feed pump and sprayed onto the solid catalyst via a spray nozzle at a temperature of 80 C. Once the entire solution has been applied and the substrate is dry, the catalyst formulation is further dried at 80 C. for 2 hours.

(76) Sample D2 was made by adding 1.0 wt % of BMMIM[OTf] (1-Butyl-2,3-dimethylimidazolium triflate) on Sample D. In order to make Sample D2, 1.2 g of the Ionic liquid BMMIM[OTf] were dissolved in 150 ml deionized water. At the same time 120 g of the dry Sample D is fluidized in a reaction chamber with synthetic air as the process gas. The solution of BMMIM[OTf] in water was Introduced into the reaction chamber at a flow rate of 5 ml/min via a feed pump and sprayed onto the solid catalyst via a spray nozzle at a temperature of 80 C. Once the entire solution has been applied and the substrate is dry, the catalyst formulation is further dried at 80 C. for 2 hours.

(77) Sample D3 was made by adding 2.0 wt % of BMMIM[OTf] 1-Butyl-2,3-dimethylimidazolium triflate) on Sample D. In order to make Sample D3, 2.4 g of the ionic liquid BMMIM[OTf] were dissolved in 150 ml deionized water. At the same time 120 g of the dry Sample D is fluidized in a reaction chamber with synthetic air as the process gas. The solution of BMMIM[OTf] in water was introduced into the reaction chamber at a flow rate of 5 ml/min via a feed pump and sprayed onto the solid catalyst via a spray nozzle at a temperature of 80 C. Once the entire solution has been applied and the substrate is dry, the catalyst formulation is further dried at 80 C. for 2 hours.

(78) Sample D4 was made by adding 3.0 wt % of BMMIM[OTf] (1-Butyl-2,3-dimethylimidazolium triflate) on Sample D. In order to make Sample D4, 3.6 g of the ionic liquid BMMIM[OTf] were dissolved in 150 ml deionized water. At the same time 120 g of the dry Sample D is fluidized in a reaction chamber with synthetic air as the process gas. The solution of BMMIM[OTf] in water was introduced into the reaction chamber at a flow rate of 5 ml/min via a feed pump and sprayed onto the solid catalyst via a spray nozzle at a temperature of 80 C. Once the entire solution has been applied and the substrate is dry, the catalyst formulation is further dried at 80 C. for 2 hours.

(79) Sample D1 was made by impregnation of Sample D with a BMMIM[OTf] (1-Butyl-2,3-dimethylimidazolium triflate) solution containing 0.5 g of BMMIM[OTf] in 38 ml deionized water. The clear solution is added to 120 g of dry Sample D. The mixture is then mixed at room temperature for approx. 60 minutes. The catalyst formulation is then dried at 80 C. for 16 h to finally obtain Sample D1.

Example 6

(80) Samples prepared in Example 5 were tested as prepared in a bench scale test unit at typical front-end hydrogenation conditions. In the test, a simulated de-ethanizer feed containing 0.35 mol % acetylene, 20 mol % hydrogen, 0.02 mol % CO, 45 mol % ethylene, and balance methane was passed over a 25 ml catalyst bed at 500 psig (35.5 bar) in total pressure and 7000 h.sup.1 in Gas Hourly Space Velocity (GHSV), while the bed temperature was gradually increased from about 35 C. The acetylene concentration at the reactor outlet was monitored with an on-line gas chromatograph (GC). The acetylene concentration at reactor outlet continued decreasing with Increasing temperature until reaching <25 ppm. The temperature at this point was defined as the clean up temperature (T1). Catalyst bed temperature was further increased until 105 C. (the maximum temperature the water bath could reach) or a certain temperature (T2), at which the outlet ethane concentration was >2% due to the increased non-selective reaction of hydrogen with ethylene. The temperature range between T1 and T2 is called the operation window. Test results of Sample D and Samples D1 to D4 and D1 are listed in the table below.

(81) TABLE-US-00002 Front End Deethanizer Feed Test Results Operation Selectivity T1 [ C.] T2 [ C.] Window [ C.] at T1 [%] Sample D 52 57 5 1 Sample D1 61 97 36 52 Sample D2 61 105 44 61 Sample D3 69 >105 >36 48 Sample D4 73 >105 >32 56 Sample D1 67 99 32 38

(82) The operation window as well as the selectivity markedly increase with increasing BMMIM[OTf] content. The optimum BMMIM[OTf] loading seems to be 0.5-1%. At higher loading, the runaway temperature continued to increase at the expense of a higher Tl temperature. Adding BMMIM[OTf] onto Sample D can be realized by coating or wet impregnation; and both methods can generate a new catalyst with significantly improved operation window.

Example 7

(83) Sample E is a commercial front end selective hydrogenation catalyst that is supplied by Sd-Chemie AG under the trade name OleMax 250. It contains 0.018 wt % Pd on 44 mm alumina tablets with a BET surface area of about 4.0 m.sup.2/g.

(84) Sample E1 was made by adding 1.0 wt % of BMMIM[OTf] (1-Butyl-2,3-dimethylimidazolium triflate) on Sample E. In order to make Sample E1, 1.2 g of the ionic liquid BMMIM[OTf] were dissolved in 150 ml deionized water. At the same time 120 g of the dry Sample E is fluidized in a reaction chamber with synthetic air as the process gas. The solution of BMMIM[OTf] in water was introduced into the reaction chamber at a flow rate of 5 ml/min via a feed pump and sprayed onto the solid catalyst via a spray nozzle at a temperature of 80 C. Once the entire solution has been applied and the substrate is dry, the catalyst formulation is further dried at 80 C. for 2 hours.

(85) Sample E2 was made by adding 2.0 wt % of BMMIM[OTf] (1-Butyl-2,3-dimethylimidazolium triflate) on Sample E. In order to make Sample E2, 2.4 g of the ionic liquid BMMIM[OTf] were dissolved in 150 ml deionized water. At the same time 120 g of the dry Sample E is fluidized in a reaction chamber with synthetic air as the process gas. The solution of BMMIM[OTf] in water was introduced Into the reaction chamber at a flow rate of 5 ml/min via a feed pump and sprayed onto the solid catalyst via a spray nozzle at a temperature of 80 C. Once the entire solution has been applied and the substrate is dry, the catalyst formulation is further dried at 80 C. for 2 hours.

(86) Sample E3 was made by adding 3.0 wt % of BMMIM[OTf] 1-Butyl-2,3-dimethylimidazolium triflate) on Sample E. In order to make Sample E3, 3.6 g of the ionic liquid BMMIM[OTf] were dissolved in 150 ml deionized water. At the same time 120 g of the dry Sample E is fluidized in a reaction chamber with synthetic air as the process gas. The solution of BMMIM[OTf] in water was introduced into the reaction chamber at a flow rate of 5 ml/min via a feed pump and sprayed onto the solid catalyst via a spray nozzle at a temperature of 80 C. Once the entire solution has been applied and the substrate is dry, the catalyst formulation is further dried at 80 C. for 2 hours.

Example 8

(87) Sample E, Sample E1, Sample E2 and Sample E3 were tested after in-situ reduction at 94 C. for 1 hour in a bench scale test unit at typical front-end hydrogenation conditions. In the test, a simulated de-ethanizer feed containing 0.35 mol % acetylene, 20 mol % hydrogen, 0.02 mol % CO, 45 mol % ethylene, and balance methane was passed over a 25 ml catalyst bed at 500 psig (35.5 bar) in total pressure and 7000 h.sup.1 in Gas Hourly Space Velocity (GHSV), while the bed temperature was gradually increased from about 35 C. The acetylene concentration at the reactor outlet was monitored with an on-line gas chromatograph (GC). The acetylene concentration at reactor outlet continued decreasing with increasing temperature until reaching <25 ppm. The temperature at this point was defined as the clean up temperature (T1). Catalyst bed temperature was further increased until 105 C. (the maximum temperature the water bath could reach) or a certain temperature (T2), at which the outlet ethane concentration was >2% due to the increased non-selective reaction of hydrogen with ethylene. The temperature range between T1 and 12 is called the operation window. Test results of Sample E and Samples E1 to E3 are listed In the table below.

(88) TABLE-US-00003 Test Results of Sample E and Samples E1 to E3 Operation Selectivity T1 [ C.] T2 [ C.] Window [ C.] at T1 [%] Sample E 53 62 9 5 Sample E1 53 69 16 65 Sample E2 52 81 29 74 Sample E3 62 92 30 78

(89) Upon addition of BMMIMM[OTf] onto the Pd/alumina catalyst, the operation window increases linearly up to a loading of 2% and then stays constant at 30 C. At higher loading, both T1 and operation window increased.

Example 9

(90) Comparative Sample F is a commercial selective hydrogenation catalyst that is supplied by Sd-Chemie AG under trade name OleMax 201. It contains 0.03 wt % Pd and 0.18 wt % Ag on 2-4 mm alumina spheres with a BET surface area of about 35 m.sup.2/g.

(91) Comparative Sample F1 was made by adding 0.5 wt % of EMIM[EtSO.sub.4] (1-ethyl-3-methylimidazolium ethylsulfate) onto Sample F by incipient wetness impregnation method. The EMIM[EtSO.sub.4] solution contains 0.5 g of EMIM[EtSO.sub.4] in 60 ml deionized water. The clear solution was added to 100 g of Comparative Sample F and mixed for about 5 min. The catalyst formulation is then dried at 80 C. for 16 hr to obtain the final product.

(92) Comparative Sample F2 was made by adding 1.0 wt % of EMIM[EtSO.sub.4] (1-ethyl-3-methylimidazolium ethylsulfate) onto Sample F by incipient wetness impregnation method. The EMIM[EtSO.sub.4] solution contains 1 g of EMIM[EtSO.sub.4] in 60 ml deionized water. The clear solution was added to 100 g of Comparative Sample F and mixed for about 5 min. The catalyst formulation is then dried at 80 C. for 16 hr to obtain final product.

(93) Sample D2 was made by adding 0.5 wt % EMIM[EtSO.sub.4] (1-ethyl-3-methylimidazolium ethylsulfate) on Sample D by incipient wetness impregnation. The EMIM[EtSO.sub.4] solution contains 0.5 g of EMIM[EtSO.sub.4] in 24 ml deionized water, The clear solution was added to 100 g of Sample D and mixed for about 5 min. The catalyst formulation is then dried at 80 C. for 16 hr to obtain final product.

(94) Sample D3 was made by adding 1 wt % EMIM[EtSO.sub.4] (1-ethyl-3-methylimidazolium ethylsulfate) on Sample D by incipient wetness impregnation. The EMIM[EtSO.sub.4] solution contains 1 g of EMIM[EtSO.sub.4] in 24 ml deionized water. The clear solution was added to 100 g of Sample D and mixed for about 5 min. The catalyst formulation is then dried at 80 C. for 16 hr to obtain final product.

Example 10

(95) Samples and Comparative Samples prepared in Example 9 were tested as prepared in a bench scale test unit at typical front-end hydrogenation conditions. In the test, a simulated de-ethanizer feed containing 0.35 mol % acetylene, 20 mol % hydrogen, 0.02 mol % CO, 45 mol % ethylene, and balance methane was passed over a 25 ml catalyst bed at 500 psig (35.5 bar) in total pressure and 7000 h.sup.1 in Gas Hourly Space Velocity (GHSV), while the bed temperature was gradually increased from about 35 C. The acetylene concentration at the reactor outlet was monitored with an on-line gas chromatograph (GC). The acetylene concentration at reactor outlet continued decreasing with increasing temperature until reaching <25 ppm. The temperature at this point was defined as the clean up temperature (T1). Catalyst bed temperature was further increased until 105 C. (the maximum temperature the water bath could reach) or a certain temperature (T2), at which the outlet ethane concentration was >2% due to the increased non-selective reaction of hydrogen with ethylene. The temperature range between T1 and T2 is called the operation window. Test results of Sample F2 and F3 did not run away at the maximum temperature the test unit could reach: the ethane make was 0.35% at 102 C. for both catalysts. Their T2's for 2% ethane make were calculated by fitting the data at temperatures above complete acetylene conversion with a first order kinetic model.

(96) TABLE-US-00004 Front End Deethanizer Feed Test Results T1 T2 T1 Selectivity at T1 Ethane Make [ C.] [ C.] T2 [ C.] [%] at 102 C. [%] Sample F 51 53 2 5 Not operable Sample F1 54 75 21 76 Not operable Sample F2 59 80 21 86 Not operable Sample D 52 57 5 1 Not operable Sample D2 65 148 83 91 0.35 Sample D3 66 149 83 94 0.35

(97) It appears that EMIM[EtSO.sub.4] has much lower impact on Sample F than on Sample D.