PROCESS FOR CONTINUOUS HETEROGENEOUSLY CATALYZED PARTIAL DEHYDROGENATION OF AT LEAST ONE HYDROCARBON TO BE DEHYDROGENATED

Abstract

A process for continuous heterogeneously catalyzed partial dehydrogenation of at least one hydrocarbon to be dehydrogenated in a reactor which is manufactured from a composite material which consists, on its side in contact with the reaction chamber, of a steel B with specific elemental composition which, on its side facing away from the reaction chamber, either directly or via an intermediate layer of copper, or of nickel, or of copper and nickel, is plated onto a steel A with specific elemental composition, and also partial oxidations of the dehydrogenated hydrocarbon and the reactor itself.

Description

EXAMPLES AND COMPARATIVE EXAMPLES

Experimental Description

• • 1. Configuration of the reaction tubes

The geometry of the reaction tubes is:

length 0.55 mm

external diameter (A) from 21.34 to 22 mm

wall thickness (W) from 2 to 2.77 mm

The particular reaction tube is filled over its entire length with inert spheres of steatite C 220 from CeramTec. The sphere diameter is from 1.5 mm to 2.5 mm with essentially uniform distribution.

• • 2. The material used for the reaction tube is 7 different materials.
  • Material 1 (M1): stainless steel of DIN materials number 1.4841 (A=22 mm, W=2 mm),
  • Material 2 (M2): stainless steel of DIN materials number 1.4541 (A=22 mm, W=2 mm),
  • Material 3 (M3): stainless steel of DIN materials number 1.4910 (A=22 mm, W=2 mm),
  • Material 4 (M4): stainless steel of DIN materials number 1.4893 with the following composition (A=21.34 mm, W=2.77 mm):
    • 20.87% by weight of Cr,
    • 10.78% by weight of Ni,
    • 1.54% by weight of Si,
    • 0.161% by weight of N,
    • 0.082% by weight of C,
    • 0.75% by weight of Mn,
    • 0.02% by weight of P,
    • 0.0026% by weight of S,
    • 0.05% by weight of Ce, and,
    • apart from these, Fe and impurities resulting from production, the percentages each being based on the total weight.
  • Material 5 (M5): stainless steel of DIN materials number 1.4841 (wall thickness: 1 mm), applied directly to stainless steel of DIN materials number 1.4910 (wall thickness: 1 mm) (A=22 mm).
  • Material 6 (M6): nickel-base material 2.4642 (A=22 mm, W=2 mm) with the elemental composition:
    • 8.70% by weight of Fe,
    • 27.85% by weight of Cr,
    • 0.02% by weight of C,
    • 0.15% by weight of Si,
    • 0.2% by weight of Mn,
    • and, apart from these, Ni and impurities resulting from production, the percentages each being based on the total weight.
  • Material 7 (M7): stainless steel of DIN materials number 1.4876 (A=22 mm, W=2 mm)
  • 3. The different reaction tubes are each charged with the following starting gas stream, as is typical in its composition for an inventive heterogeneously catalyzed dehydrogenation of propane to propylene:
    • 34.4% by volume of propane,
    • 55.6% by volume of nitrogen,
    • 3.2% by volume of oxygen, and
    • 6.8% by volume of steam.
  • 4. The reaction tube was in each case mounted in a radiative oven (electrically heated ceramic body with hollow cylindrical guide for accommodating the reaction tube with a gap width of from 0.13 to 0.15 cm to the reaction tube outer wall).
  • 5. The particular reaction tube is flowed through as described (P (reactor outlet pressure)=1 atm) by the starting gas stream (this has an inlet temperature of 200° C. in each case). At the same time, the temperature T^A of the outer wall of the reaction tube is increased such that the maximum temperature T^M in the reaction tube increases from 400° C. to 700° C. in an essentially linear manner with a gradient of 10° C./h (this simulates the compensation of a catalyst bed being deactivated in continuous operation by increasing the reaction temperature).

Subsequently, the regeneration of a dehydrogenation catalyst bed is simulated. To this end, the reaction tube is flowed through first with 420 ml (STP)/min of N₂ of inlet temperature 200° C. while keeping the temperature T^M at 700° C.

While retaining the temperature T^M=700° C., the following gas flow program is passed through:

• • over 60 min, lean air (mixture of air (85.4 ml (STP)/min) and N₂ ((341.6 ml (STP)/min));

then—over 60 min, 417 ml (STP)/min of air;

then—over 15 min, 417 ml (STP)/min of N₂;

then—over 60 min, 168 ml (STP)/min of H₂.

The particular reaction tube, flowed through by the particular feed, was then brought from T^M=700° C. to T^M=400° C. in an essentially linear manner with a T^M gradient of 10° C./h.

From attainment of the temperature T^M=400° C., the temperature T^A of the outer wall of the reaction tube is in turn increased such that the maximum temperature T^M in the reaction tube increases from 400° C. to 700° C. in an essentially linear manner with a gradient of 10° C./h. Subsequently, as described above, the regeneration of a dehydrogenation catalyst bed is again simulated, etc.

After a total operating time of 1000 h, the particular reaction tube is examined for carburization, metal dusting, long-term embrittlement (comparison of the notched impact resistance KZ before the start of the particular experiment (KZ_V) and at the end (KZ_E) of performance of the experiment for 1000 hours) (for this purpose, the sample is at room temperature in each case).

The following table shows the resulting results.

			Long-term	KZV	KZE
	Carburization	Metal dusting	embrittlement	[J]	[J]
M1	−	−	++	>40	<5
M2	++	+	−	>>40	>>40
M3	++	+	−	>>40	>>40
M4	0	−	+	>40	<10
M5	−	−	−	>>40	>>40
M6	−	−	−	>>40	>>40
M7	++	+	−	>>40	>>40

In the table, the following meanings apply:

−: no occurrence

0: moderate occurrence

+: high occurrence

++: very high occurrence

For materials M2, M3, M5, M6 and M7, the values for KZ_V and KZ_E are essentially indistinguishable within the precision of measurement.

In addition, at the start of the particular reaction tube, the amount of propane converted as it passes through the reaction tube is determined (in each case at the temperatures T^A=500° C., 600° C., 650° C. and 700° C.

The lowest conversion values are determined in the cases of M1, M5 and M6. The conversions also increase with T^A.

U.S. Provisional Patent Application No. 60/816592, filed on Jun. 27, 2006, is incorporated into the present patent application by literature reference.

With regard to the abovementioned teachings, numerous changes and deviations from the present invention are possible. It can therefore be assumed that the invention, within the scope of the appended claims, can be performed differently from the way described specifically herein.

Claims

1. A process for continuous heterogeneously catalyzed partial dehydrogenation of at least one hydrocarbon to be dehydrogenated in the gas phase, comprising a procedure in which a reaction chamber which is enclosed by a shell which is in contact with the reaction chamber and has at least one first orifice for feeding at least one starting gas stream into the reaction chamber and at least one second orifice for withdrawing at least one product gas stream from the reaction chamber, at least one starting gas stream comprising at least one hydrocarbon to be dehydrogenated is fed continuously,in the reaction chamber, the at least one hydrocarbon to be dehydrogenated is conducted through at least one catalyst bed disposed in the reaction chamber and, with generation of a product gas comprising the at least one dehydrogenated hydrocarbon, unconverted hydrocarbon to be dehydrogenated and molecular hydrogen and/or steam, is dehydrogenated partially in an oxidative or nonoxidative manner to at least one dehydrogenated hydrocarbon, andat least one product gas stream is withdrawn continuously from the reaction chamber,

2. The process according to claim 1, wherein the coefficients of thermal expansion of steel A and steel B of the composite material at 500° C. and 1 atm differ by ≦2·10−6 m/m·K.

3. The process according to claim 1, wherein the coefficients of thermal expansion of steel A and steel B of the composite material at 500° C. and 1 atm differ by ≦1.75·10−6 m/m·K.

4. The process according to claim 1, wherein the coefficients of thermal expansion of steel A and steel B of the composite material at 500° C. and 1 atm differ by ≦1.50·10−6 m/m·K.

5. The process according to claim 1, wherein the coefficients of thermal expansion of steel A and steel B of the composite material at 500° C. and 1 atm differ by ≦1.25·10−6 m/m·K.

6. The process according to claim 1, wherein the coefficients of thermal expansion of steel A and steel B of the composite material at 500° C. and 1 atm differ by ≦1.0·10−6 m/m·K.

7. The process according to any of claims 1 to 6, wherein the thickness of steel B of the composite material is from 0.2 to 25 mm.

8. The process according to any of claims 1 to 6, wherein the thickness of steel B of the composite material is from 1 to 10 mm.

9. The process according to any of claims 1 to 6, wherein the thickness of steel B of the composite material is from 2 to 8 mm.

10. The process according to any of claims 1 to 9, wherein the thickness of steel A of the composite material is from 10 to 150 mm.

11. The process according to any of claims 1 to 9, wherein the thickness of steel A of the composite material is from 20 to 100 mm.

12. The process according to any of claims 1 to 9, wherein the thickness of steel A of the composite material is from 60 to 100 mm.

13. The process according to any of claims 1 to 9, wherein the thickness of steel A of the composite material is from 20 to 50 mm.

14. The process according to any of claims 1 to 13, wherein steel B of the composite material is plated directly onto steel A.

15. The process according to any of claims 1 to 13, wherein steel B of the composite material is plated onto steel A via an intermediate layer of copper, or of nickel, or of copper and nickel, and the thickness of the intermediate layer is ≧0.1 mm and ≦3 mm.

16. The process according to claim 15, wherein the thickness of the intermediate layer is ≧0.2 mm and ≦2 mm.

17. The process according to claim 15, wherein the thickness of the intermediate layer is ≧0.3 mm and ≦1 mm.

18. The process according to any of claims 1 to 17, wherein the content of Si in steel A of the composite material is ≦0.6% by weight.

19. The process according to any of claims 1 to 17, wherein the content of Si in steel A of the composite material is ≦0.4% by weight.

20. The process according to any of claims 1 to 17, wherein the content of Si in steel A of the composite material is ≦0.1% by weight.

21. The process according to any of claims 1 to 20, wherein steel B of the composite material has the elemental composition

22. The process according to any of claims 1 to 21, wherein steel A of the composite material has the elemental composition

23. The process according to any of claims 1 to 22, wherein the plating-on is effected by explosive plating.

24. The process according to any of claims 1 to 23, wherein the hydrocarbon to be dehydrogenated is a C2— to C16-alkane.

25. The process according to any of claims 1 to 24, wherein the hydrocarbon to be dehydrogenated is at least one hydrocarbon from the group comprising ethane, propane, n-butane, isobutane, n-pentane, isopentane, n-hexane, n-heptane, n-octane, n-nonane, n-decane, n-undecane, n-dodecane, n-tridecane, n-tetradecane, n-pentadecane and n-hexadecane.

26. The process according to any of claims 1 to 25, wherein the hydrocarbon to be dehydrogenated is ethane, propane, n-butane and/or isobutane.

27. The process according to any of claims 1 to 26, wherein the hydrocarbon to be dehydrogenated is propane and the dehydrogenated hydrocarbon is propylene.

28. The process according to any of claims 1 to 27, wherein the starting gas stream comprises steam.

29. The process according to any of claims 1 to 28, wherein the starting gas stream comprises molecular oxygen.

30. The process according to any of claims 1 to 29, wherein the catalyst bed is a fixed catalyst bed.

31. The process according to any of claims 1 to 30, wherein the heterogeneously catalyzed partial dehydrogenation is a nonoxidative dehydrogenation.

32. The process according to any of claims 1 to 30, wherein the heterogeneously catalyzed partial dehydrogenation is an oxidative dehydrogenation.

33. The process according to any of claims 1 to 30, wherein the heterogeneously catalyzed partial dehydrogenation is a heterogeneously catalyzed oxydehydrogenation.

34. The process according to any of claims 1 to 30, wherein the heterogeneously catalyzed partial dehydrogenation is an adiabatic conventional heterogeneously catalyzed dehydrogenation.

35. The process according to any of claims 1 to 30, wherein the heterogeneously catalyzed partial dehydrogenation is a conventional heterogeneously catalyzed partial dehydrogenation and the reaction chamber is a tray reaction chamber.

36. The process according to claim 35, wherein the conventional heterogeneously catalyzed partial dehydrogenation is an oxidative conventional heterogeneously catalyzed partial dehydrogenation.

37. The process according to claim 36, which is performed in an adiabatic reaction chamber.

38. The process according to any of claims 1 to 37, wherein the starting gas stream fed to the reaction chamber comprises: from ≧0 to 20% by volume of propylene,from ≧0 to 1% by volume of acrolein,from ≧0 to 0.25% by volume of acrylic acid,from ≧0 to 20% by volume of COx,from 5 to 50% by volume of propane,from 20 to 80% by volume of nitrogen,from ≧0 to 5% by volume of oxygen,from ≧0 to 20% by volume of H2O andfrom ≧0 to 10% by volume of H2.

39. The process according to any of claims 1 to 38, wherein the product gas stream withdrawn from the reaction chamber is used as such or after removal of at least a portion of its constituents other than the dehydrogenated hydrocarbon and the hydrocarbon to be dehydrogenated to charge at least one oxidation reactor, and the dehydrogenated hydrocarbon present therein is subjected in this oxidation reactor to a selective heterogeneously catalyzed partial gas phase oxidation with molecular oxygen to give a product gas mixture B comprising the partial oxidation product.

40. The process according to claim 39, wherein the hydrocarbon to be dehydrogenated is propane, the dehydrogenated hydrocarbon is propylene and the partial oxidation product is acrolein, acrylic acid or a mixture thereof.

41. The process according to claim 39, wherein, in a separation zone B of the selective heterogeneously catalyzed partial gas phase oxidation, partial oxidation product is subsequently removed from the product gas mixture B and, from the remaining residual gas comprising unconverted hydrocarbon to be dehydrogenated, molecular oxygen and any unconverted dehydrogenated hydrocarbon, at least a portion comprising unconverted hydrocarbon to be dehydrogenated is recycled as partial oxidation cycle gas into the process for heterogeneously catalyzed partial dehydrogenation of the hydrocarbon to be dehydrogenated.

42. The process according to claim 41, wherein the partial oxidation product, in separation zone B, is removed from product gas mixture B by conversion to the condensed phase.

43. The process according to claim 42, wherein the partial oxidation product is acrylic acid and the conversion to the condensed phase is effected by absorptive and/or condensative measures.

44. The process according to claim 43, wherein a removal of acrylic acid from the condensed phase is undertaken using at least one thermal separation process.

45. The process according to claim 44, wherein the at least one thermal separation process comprises a crystallizative removal of acrylic acid from the liquid phase.

46. The process according to claim 45, wherein the crystallizative removal is a suspension crystallization.

47. The process according to claim 44, wherein the removal of acrylic acid is followed by a process for free-radical polymerization in which acrylic acid removed is free-radically polymerized to prepare polymers.

48. The process according to claim 44, wherein the removal of acrylic acid is followed by a process for preparing acrylic esters in which acrylic acid removed is esterified with an alcohol.

49. The process according to claim 48, wherein the process for preparing an acrylic ester is followed by a process for free-radical polymerization in which acrylic ester thus prepared is polymerized.

50. A shell E which encloses an interior I and has at least one first orifice O1 for feeding at least one gas stream S into the interior I and at least one second orifice O2 for withdrawing a gas stream S fed to the interior I beforehand via the at least one first orifice O1 from the interior I, the shell E being manufactured from a composite material which, on its side B in contact with the reaction chamber, consists of steel B of the following elemental composition:

51. A shell E according to claim 50 whose interior I comprises at least one dehydrogenation catalyst.

52. A shell E according to claim 50 or 51 whose interior I comprises at least one support grid.

53. A shell E according to any of claims 50 to 52 which has an annular segment R.

54. A shell E according to claim 53 where the ratio of V1=D:A, formed from half D of the difference between the external diameter A and the internal diameter of the annular segment R, is from 1:10 to 1:1000.

55. A shell E according to claim 54 where V1 is from 1:40 to 1:500.

56. A shell E according to any of claims 53 to 55 where the ratio V2=H:A, formed from the separation H of the two parallel circular planes delimiting the annular segment R and the external diameter A of the annular segment is >1.

57. A shell E according to any of claims 53 to 55 where the ratio V2=H:A, formed from the separation H of the two parallel circular planes delimiting the annular segment R and the external diameter of the annular segment is ≦1.

58. A shell E according to any of claims 50 to 52 which has a hollow spherical zone segment K.

59. A shell E according to any of claims 50 to 58 which has thermal insulation material on its side facing away from the interior I.

60. A process for heterogeneously catalyzed partial dehydrogenation of a hydrocarbon, which is performed in the interior I of a shell E according to any of claims 50 to 59.

61. The use of a shell E according to any of claims 50 to 59 or according to any of claims 63, 65, 66 for carrying out a heterogeneously catalyzed partial dehydrogenation of a hydrocarbon.

62. The process according to any of claims 1 to 49, wherein the steel B has been alonized, alitized and/or aluminized on its side in contact with the reaction chamber.

63. A shell E according to any of claims 50 to 59 where the steel B has been alonized, alitized and/or aluminized on the side in contact with the interior I.

64. The process according to any of claims 1 to 49 or according to claim 62, wherein steel A and steel B of the composite material are austenitic steels.

65. A shell E according to any of claims 50 to 59 or according to claim 63, wherein steel A and steel B of the composite material are austenitic steels.

66. A shell E according to any of claims 50 to 59 or according to either of claims 63, 65 which has thermal insulation material mounted on its side facing toward the interior I.