CATALYST AND METHODS FOR THE ISOMERISATION OF OLEFINS FROM OLEFIN-CONTAINING HYDROCARBON MIXTURES HAVING 4-20 C-ATOMS

Abstract

The present invention provides a catalyst comprising alumina as carrier material and palladium or platinum as active component, obtainable by a) impregnating an alumina carrier with a solution comprising at least one salt of the active component palladium or platinum, b) drying the catalyst thus obtained, c) treating the catalyst thus obtained with hydrogen, or a mixture of hydrogen and at least one inert gas, for a period of 1 to 24 hours at a temperature of 30 to 200? C., and d) thereafter keeping the catalyst thus reduced in the presence of hydrogen, or a mixture of hydrogen and at least one inert gas, for a period of 1 hour to 10 days at a temperature of 10 to 100? C.

The catalyst provided by the invention is useful in processes for isomerization of olefins from olefin-containing hydrocarbonaceous mixtures having 4 to 20 carbon atoms at temperatures of 10 to 150? C. and pressures of 1 to 35 bar.

Claims

1.-29. (canceled)

30. A catalyst comprising alumina as carrier material and palladium or platinum as active component, obtainable by a) impregnating an alumina carrier with a solution comprising at least one salt of the active component palladium or platinum, b) drying the catalyst thus obtained, c) treating the catalyst thus obtained with hydrogen, or a mixture of hydrogen and at least one inert gas, for a period of 1 to 24 hours at a temperature of 30 to 200? C., and d) thereafter keeping the catalyst thus reduced in the presence of hydrogen, or a mixture of hydrogen and at least one inert gas, for a period of 1 hour to 10 days at a temperature of 10 to 100? C.

31. The catalyst according to claim 30 wherein the catalyst is subjected after process step c) and before process step d) to an additional process step c.sub.1) of being maintained in the hydrogen atmosphere for a further 1 to 10 hours at a temperature of 10 to 100? C. with the proviso that the temperatures in process steps c), c.sub.1) and d) differ from each other.

32. The catalyst according to claim 30 wherein the catalyst is calcined after drying in process step b) and before the hydrogen treatment in process step c).

33. The catalyst according to claim 30 wherein the catalyst is brought into contact with atmospheric oxygen following the hydrogen treatment in process step d).

34. The catalyst according to claim 30 wherein the carrier material used comprises molded spheres of alumina.

35. The catalyst according to claim 34 wherein the molded spheres are from 1 to 6 mm in diameter.

36. The catalyst according to claim 30 wherein the active component is predominantly present therein concentrated into an eggshell at the catalyst surface.

37. The catalyst according to claim 30 wherein the active component is present therein in a highly disperse state.

38. The catalyst according to claim 37 wherein the catalyst has a dispersity in the range from 20 to 60% (as measured via CO sorption to DIN 66136-3).

39. The catalyst according to claim 30 wherein the active component used is palladium in an amount of 0.05 to 2.0 wt %, based on total catalyst weight.

40. The catalyst according to claim 39 wherein the solution used to impregnate the alumina carrier comprises palladium chloride and/or palladium hydroxide.

41. The catalyst according to claim 30 wherein the alumina carrier used has a BET surface area of 20 to 200 m.sup.2/g.

42. The process for preparing the catalyst as claimed in claim 30 by a) impregnating an alumina carrier with a solution comprising at east one salt of the active component palladium or platinum, b) drying the catalyst thus obtained, c) treating the catalyst thus obtained with hydrogen, or a mixture of hydrogen and at least one inert gas, for a period of 1 to 24 hours at a temperature of 30 to 200? C. after drying, and d) keeping the catalyst thus reduced in the presence of hydrogen, or a mixture of hydrogen and at least one inert gas, for a period of 1 hour to 10 days at a temperature of 10 to 100? C.

43. The process for preparing a catalyst according to claim 42 wherein the catalyst is brought into contact with atmospheric oxygen following the hydrogen treatment in process step d).

44. The process for preparing a catalyst according to claim 42 wherein the catalyst is subjected after process step c) and before process step d) to an additional process step c.sub.1) of being maintained in the hydrogen atmosphere for a further 1 to 10 hours at a temperature of 10 to 100? C. with the proviso that the temperatures in process steps c), c.sub.1) and d) differ from each other.

45. The process for preparing a catalyst according to claim 42 wherein the catalyst is calcined after drying in process step b) and before the hydrogen treatment in process step c).

46. The process for preparing a catalyst according to claim 42 wherein the alumina carrier used in step a) is obtained by a.sub.1) treating an aluminum-containing raw material with water, a dilute acid or a dilute base, a.sub.2) molding shapes, a.sub.3) drying the molded shapes, and a.sub.4) calcining the dried molded shapes.

47. The process for preparing a catalyst according to claim 46 wherein the aluminum-containing raw material used in process step a.sub.1) comprises gibbsite.

48. The process for preparing a catalyst according to claim 46 wherein the alumina carrier is subjected to a hydrothermal treatment in an autoclave prior to said drying step a.sub.3).

49. The process for preparing a catalyst according to claim 42 wherein the solution used to impregnate the alumina carrier in process step a) comprises one or more salts of palladium.

50. A process for isomerization of olefins from olefin-containing hydrocarbonaceous mixtures having 4 to 20 carbon atoms wherein the process is conducted at temperatures of 10 to 150? C. and pressures of 1 to 35 bar in the presence of the catalyst as claimed in claim 30.

51. The process according to claim 50 wherein olefins having external double bonds are isomerized into olefins having internal double bonds.

52. The process according to claim 50 wherein 1-butene is isomerized into 2-butene.

53. The process according to claim 50 wherein the isomerization is combined with a selective hydrogenation of diolefins in the olefin-containing hydrocarbonaceous mixtures.

54. The process according to claim 52 wherein the ratio of 2-butene to 1-butene at the point of exit from the isomerization stage is between 3 and 30.

55. The process according to claim 54 wherein the ratio of 2-butene to 1-butene at the point of exit from the isomerization stage is between 4 and 25.

56. A process for activating a catalyst comprising alumina as carrier material and palladium or platinum as active component, which process comprises c) treating the catalyst with hydrogen, or a mixture of hydrogen and at least one inert gas, for a period of 1 to 24 hours at a temperature of 30 to 200? C., and d) thereafter keeping the catalyst thus reduced in the presence of hydrogen, or a mixture of hydrogen and at least one inert gas, for a period of 1 hour to 10 days at a temperature of 10 to 100? C.

57. The process for activating a catalyst according to claim 56, wherein said catalyst is obtainable by a) impregnating an alumina carrier with a solution comprising at least one salt of the active component palladium or platinum, and b) drying the catalyst thus obtained.

58. The process for activating a catalyst according to claim 56, wherein the catalyst is brought into contact with atmospheric oxygen following the hydrogen treatment in process step d).

Description

[0098] Embodiments of the present invention will now be more particularly described by way of example.

1. Preparation of Catalysts

1.1 Catalyst a (Comparative)

[0099] In a mixer, boehmite (Versal 250 from Euro Support, Amsterdam) was moistened with water, intensively mulled until the material was efficiently moldable and then extruded into 3 mm strands. Thereafter, the strands were dried at 120? C. for 2 hours and calcined at 1000? C. for 2 hours. The strands were then impregnated with HNO.sub.3-acidic Pd(NO.sub.3).sub.2 solution (pH=0.5) by the incipient wetness method, dried at 120? C. for 12 hours and finally calcined at 330? C. for 6 hours. The palladium content of the final catalyst was 0.3 wt %. The specific BET surface area was 70 m.sup.2/g.

[0100] The catalyst was subsequently treated with hydrogen at 120? C. for 12 hours.

1.2 Catalyst B (Comparative)

[0101] Molded alpha/theta/kappa-Al.sub.2O.sub.3 spheres 3 mm in diameter and 40 m.sup.2/g in specific BET surface area were subjected to an incipient wetness impregnation with a hydrochloric acid PdCl.sub.2 solution neutralized with an NaHCO.sub.3 solution shortly before impregnation. The impregnated carrier was subsequently washed and dried at 150? C. for 12 hours. The palladium content of the final catalyst was 0.25 wt %.

[0102] The catalyst was subsequently treated with hydrogen at 120? C. for 12 hours.

1.3 Catalyst C (Comparative)

[0103] Molded alpha/theta/kappa-Al.sub.2O.sub.3 spheres 3 mm in diameter and 40 m.sup.2/g in specific BET surface area were subjected to an incipient wetness impregnation with a hydrochloric acid PdCl.sub.2 solution neutralized with an NaHCO.sub.3 solution shortly before impregnation. The impregnated carrier was subsequently washed and dried at 150? C. for 12 hours. The palladium content of the final catalyst was 0.25 wt %.

1.4 Catalyst D (Comparative)

[0104] Molded alpha/theta/kappa-Al.sub.2O.sub.3 spheres 3 mm in diameter and 40 m.sup.2/g in specific BET surface area were subjected to an incipient wetness impregnation with a hydrochloric acid PdCl.sub.2 solution neutralized with an NaHCO.sub.3 solution shortly before impregnation. The impregnated carrier was subsequently washed and dried at 150? C. for 12 hours. The palladium content of the final catalyst was 0.3 wt %.

[0105] The catalyst was subsequently treated with hydrogen at 120? C. for 12 hours.

1.5 Catalyst E (Inventive)

[0106] Molded alpha/theta/kappa-Al.sub.2O.sub.3 spheres 3 mm in diameter and 40 m.sup.2/g in specific BET surface area were subjected to an incipient wetness impregnation with a hydrochloric acid PdCl.sub.2 solution neutralized with an NaHCO.sub.3 solution shortly before impregnation. The impregnated carrier was subsequently washed and dried at 150? C. for 12 hours. The palladium content of the final catalyst was 0.25 wt %.

[0107] Thereafter, the catalyst was first treated with hydrogen at 120? C. for 12 hours and then kept in a hydrogen atmosphere for 8 hours at 60? C. and finally for a further 6 days at 30? C.

1.6 Catalyst F (Inventive)

[0108] Molded alpha/theta/kappa-Al.sub.2O.sub.3 spheres 3 mm in diameter and 40 m.sup.2/g in specific BET surface area were subjected to an incipient wetness impregnation with a hydrochloric acid PdCl.sub.2 solution neutralized with an NaHCO.sub.3 solution shortly before impregnation. The impregnated carrier was subsequently washed and dried at 150? C. for 12 hours. The palladium content of the final catalyst was 0.3 wt %.

[0109] Thereafter, the catalyst was first treated with hydrogen at 120? C. for 12 hours and then kept in a hydrogen atmosphere for 8 hours at 60? C. and finally for a further 6 days at 30? C.

1.7 Catalyst G (Inventive)

[0110] Molded alpha/theta/kappa-Al.sub.2O.sub.3 spheres 3 mm in diameter and 40 m.sup.2/g in specific BET surface area were subjected to an incipient wetness impregnation with a hydrochloric acid PdCl.sub.2 solution neutralized with an NaHCO.sub.3 solution shortly before impregnation. The impregnated carrier was subsequently washed and dried at 150? C. for 12 hours. The palladium content of the final catalyst was 0.3 wt %.

[0111] Thereafter, the catalyst was first treated with hydrogen at 120? C. for 12 hours and then kept in a hydrogen atmosphere for 8 hours at 60? C. and finally for a further 6 days at 30? C.

[0112] Subsequently, the catalyst was flushed with nitrogen at 30? C. and then treated for 2 hours with an air-nitrogen mixture in which the proportion of the air stream was incrementally raised over 1 hour to finally 50%.

2. 1-Butene (1-Bu) to 2-butene (2-Bu) hydroisomerization Experiments

[0113] The 1-butene to 2-butene isomerization experiments were each carried out in a fixed-bed reactor, equipped with recirculator and separator, in the presence of one of the catalysts itemized in the table. The substrate stream (feed) was a raffinate I comprising 0.5-0.6% by volume of the butadiene (BD) and a 0.6 to 0.7 ratio of 2-butene to 1-butene. An additional substrate stream (feed) was a raffinate II without butadiene and having a 0.8 ratio of 2-butene to 1-butene.

[0114] The reaction conditions were as follows:

TABLE-US-00001 whsv [kg/(l ? h)] 8.5 recirculation to feed ratio 1.9 cross-sectional space velocity [m.sup.3/m.sup.2/h] 39 pressure 8 bar temperature 60? C.

[0115] In the experiments, the molar H.sub.2/BD ratio in the substrate stream of raffinate I was varied between 2:1 to 3.5:1 (mol/mol) while the other parameters were all left unchanged, so that full conversion of BD was attained in all experiments. The experiment involving raffinate II used an H.sub.2 flow rate in the substrate stream on the order of magnitude of the other experiments.

[0116] The composition of the product obtained was evaluated regarding the ratio of 2-butene to 1-butene, the formation of 2-butene and n-butane (n-Bu) and also the 1-butene isomerization.

[0117] It transpired that the process of the present invention, involving the use of catalysts E, F or G, was observed to give a distinctly higher isomerization of 1-butene to 2-butene (2-butene to 1-butene ratio from above 4 to above 8) than the comparative tests involving the catalysts A, B, C and D (2-butene to 1-butene ratio between 1 and 3). At the same time, the use of catalyst E, F or G was found to give a comparably low degree of overhydrogenation versus the comparative tests (with catalysts A, B, C and D). The results are tabled hereinbelow.

TABLE-US-00002 TABLE Results of 1-butene to 2-butene hydroisomerization BD content 2-Bu/1-Bu 1-Bu n-Bu 2-Bu 2-Bu 2-Bu/1-Bu [vol %] product isomerization formation yield formation Catalyst input feed input feed stream [%]*** [wt %]**** [%]***** [wt %]****** A* 0.66 0.52 1.18 25.2 1.19 21.7 5.10 B* 0.65 0.51 2.76 56.3 0.95 54.0 12.74 C* 0.67 0.59 2.54 53.5 1.18 50.4 12.01 D* 0.73 0.47 2.14 45.5 0.93 42.6 9.15 E** 0.65 0.63 8.20 82.3 1.23 77.6 18.47 F** 0.67 0.53 4.17 68.0 1.03 64.4 14.31 G** 0.61 0.53 4.74 72.3 1.07 69.2 16.11 E.sup.+ 0.82 0.00 7.96 80.1 1.30 76.5 30.11 *comparative test on raffinate I **inventive test on raffinate I .sup.+inventive test on raffinate II (without butadiene) ***[1-Bu in hydrogenation feed] ? [1-Bu in hydrogenation product]/[1-Bu in hydrogenation feed] ****[n-Bu in hydrogenation product] ? [n-Bu in hydrogenation feed] *****[2-Bu in hydrogenation product] ? [2-Bu in hydrogenation feed]/[1-Bu in hydrogenation feed] + [BD in hydrogenation feed] ******[2-Bu in hydrogenation product]/[2-Bu in hydrogenation feed]