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1. (EP1741691) Process for the production of ethylene
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Claims

1. A process for the production of ethylene, comprising the following steps:

thermally converting a feed charge containing methane into acetylene as an intermediate, and

in situ hydrogenating the acetylene produced in the first step into ethylene by a non-catalytic hydrogen transfer mechanism.


  2. The process according to claim 1, wherein the thermal conversion is a pyrolysis or a partial oxidation process.
  3. The process according to claim 2, wherein the pyrolysis process is a two-stage process.
  4. The process according to claim 3, wherein the pyrolysis process is a high temperature pyrolysis (HTP).
  5. The process according to claim 4, wherein the methane containing feed and oxygen are preheated to 550°C to 650°C and are fed in stoichiometric ratio or with oxygen slightly below stoichiometric ratio and reacted in a combustion zone (stage 1) to form hot gases, which has a temperature of from 900°C to 2000°C and a pressure in the range of from 0.5 to 5 atmospheres, and wherein the hot combustion gas is then passed to a pyrolysis zone where methane is then introduced (stage 2) to form acetylene and wherein the pyrolysis zone is maintained at a temperature of 1300°C to 1600°C, wherein the contact time is 3 to 30 milliseconds and the pressure is maintained from 0.5 to 5 atmospheres.
  6. A process according to claim 5, wherein, in the pyrolysis zone (stage 2), the contact time is 5 to 10 milliseconds and the pressure is maintained at about 2 atmospheres.
  7. The process according to claim 6, wherein the methane containing feed is fed into the pyrolysis zone (stage 2) after preheating to about 600°C.
  8. The process according to claim 2, wherein the partial oxidation process is comprised of the preheating the methane containing feed and oxygen to from 600°C to 700°C wherein the oxygen to methane feed ratio is in sub-stoichiometric ratio from 0.5 to 0.7 and the reaction zone is at a temperature of from 1500°C to 1600°C.
  9. The process according to claim 8, wherein the oxygen to methane feed ratio is about 0.62.
  10. The process according to any of the preceding claims, wherein acetylene, before the in situ hydrogenation is cooled by partial quenching using a coolant.
  11. The process according to claim 10, wherein the coolant is selected from the group consisting of water, heavy hydrocarbons, natural gas, ethane, methanol and mixtures thereof.
  12. The process according to claim 10 or 11, wherein the final temperature of the partial quench mixture of the acetylene containing mixture is between 800°C and 950°C.
  13. The process according to claim 12, wherein the final temperature of the partial quench of the acetylene containing mixture is between 880°C and 910°C.
  14. The process according to any of claims 10 to 13, wherein the final temperature of the partial quench is achieved by spray injection of the coolant into the acetylene containing gases.
  15. The process according to any of the preceding claims, wherein the in situ hydrogenation is performed by intimately mixing the acetylene containing effluent from the thermal pyrolysis or partial oxidation zone with an alkane feed.
  16. The process according to claim 15, wherein the alkane feed rate and temperature together with the coolant rate is adjusted to keep the hydrogenation temperature from 800°C to 950°C.
  17. The process according to claim 16, wherein the alkane feed rate and temperature together with the coolant rate is adjusted to keep the hydrogenation temperature from 800°C to 910°C.
  18. The process according to any of claims 15 to 17, wherein the alkane feed is selected from the group consisting of ethane, propane, butane, iso-butane or mixtures thereof.
  19. The process according to claim 18, wherein the alkane feed is ethane.
  20. The process according to claim 18 or 19, wherein the alkane feed is fed to the hydrogenation zone either as a separate feed or mixed with the coolant.
  21. The process according to any of claims 15 to 20, wherein the alkane to acetylene molar ratio ranges from 4:1 to 0.2:1.
  22. The process according to claim 21, wherein the alkane to acetylene molar ratio ranges from 1:1 to 0.25:1.
  23. The process according to any of claims 15 to 22, wherein the contact time is from 0.01 to 1.0 seconds and the pressure is from 0.5 to 5 atmospheres.
  24. The process according to claim 23, wherein the contact time is from 0.05 to 0.8 seconds.
  25. The process according to claims 10 to 24, wherein the hydrogenation reaction zone comprises multiple partial quench zones.
  26. The process according to any of the claims 15 to 25, wherein a final quench is conducted for stabilizing the product gases containing ethylene at a temperature of from 90°C to 150°C.
  27. The process according to any of the claims 10 to 26, where the coolant is water or heavy oil or natural gas.
  28. The process according to claim 26, wherein the residual acetylene remaining in the final quench product gas together with the unconverted alkane is separated downstream and is recycled back together with the make-up alkane feed to the in situ hydrogenation zone.
  29. The process according to claim 27 or 28, wherein the unconverted methane is separated from the final quench product gas downstream and is recycled back to the primary feed with the oxygen or sent to the fuel gas.
  30. The process according to claim 13, wherein C 3+ un-saturated and aromatic compounds contained in the final effluent gases are separated downstream.
  31. The process according to any of the preceding claims, wherein the methane containing feed is natural gas.
 

Amended claims in accordance with Rule 86(2) EPC.


1. A process for the production of ethylene, comprising the following steps:

thermally converting a feed charge containing methane into acetylene as an intermediate, wherein the thermal conversion is a pyrolysis or a partial oxidation process, and

in situ hydrogenating the acetylene produced in the first step into ethylene by a non-catalytic hydrogen transfer mechanism, wherein the in situ hydrogenation is performed by intimately mixing the acetylene containing effluent from the thermal pyrolysis or partial oxidation zone with an ethane feed.

2. The process according to claim 1, wherein the pyrolysis process is a two-stage process.

3. The process according to claim 2, wherein the pyrolysis process is a high temperature pyrolysis (HTP).

4. The process according to claim 3, wherein the methane containing feed and oxygen are preheated to 550°C to 650°C and are fed in stoichiometric ratio or with oxygen slightly below stoichiometric ratio and reacted in a combustion zone (stage 1) to form hot gases, which has a temperature of from 900°C to 2000°C and a pressure in the range of from 0.5 to 5 atmospheres, and wherein the hot combustion gas is then passed to a pyrolysis zone where methane is then introduced (stage 2) to form acetylene and wherein the pyrolysis zone is maintained at a temperature of 1300°C to 1600°C, wherein the contact time is 3 to 30 milliseconds and the pressure is maintained from 0.5 to 5 atmospheres.

5. A process according to claim 4, wherein, in the pyrolysis zone (stage 2), the contact time is 5 to 10 milliseconds and the pressure is maintained at about 2 atmospheres.

6. The process according to claim 5, wherein the methane containing feed is fed into the pyrolysis zone (stage 2) after preheating to about 600°C.

7. The process according to claim 1, wherein the partial oxidation process is comprised of the preheating the methane containing feed and oxygen to from 600°C to 700°C wherein the oxygen to methane feed ratio is in sub-stoichiometric ratio from 0.5 to 0.7 and the reaction zone is at a temperature of from 1500°C to 1600°C.

8. The process according to claim 7, wherein the oxygen to methane feed ratio is about 0.62.

9. The process according to any of the preceding claims, wherein acetylene, before the in situ hydrogenation is cooled by partial quenching using a coolant.

10. The process according to claim 9, wherein the coolant is selected from the group consisting of water, heavy hydrocarbons, natural gas, ethane, methanol and mixtures thereof.

11. The process according to claim 9 or 10, wherein the final temperature of the partial quench mixture of the acetylene containing mixture is between 800°C and 950°C.

12. The process according to claim 11, wherein the final temperature of the partial quench of the acetylene containing mixture is between 880°C and 910°C.

13. The process according to any of claims 9 to 12, wherein the final temperature of the partial quench is achieved by spray injection of the coolant into the acetylene containing gases.

14. The process according to claim 1, wherein the ethane feed rate and temperature together with the coolant rate is adjusted to keep the hydrogenation temperature from 800°C to 950°C.

15. The process according to claim 14, wherein the ethane feed rate and temperature together with the coolant rate is adjusted to keep the hydrogenation temperature from 800°C to 910°C.

16. The process according to any of the preceding claims, wherein the ethane feed is fed to the hydrogenation zone either as a separate feed or mixed with the coolant.

17. The process according to any of the preceding claims, wherein the ethane to acetylene molar ratio ranges from 4:1 to 0.2:1.

18. The process according to claim 17, wherein the ethane to acetylene molar ratio ranges from 1:1 to 0.25:1.

19. The process according to any of the preceding claims, wherein the contact time is from 0.01 to 1.0 seconds and the pressure is from 0.5 to 5 atmospheres.

20. The process according to claim 19, wherein the contact time is from 0.05 to 0.8 seconds.

21. The process according to claims 9 to 20, wherein the hydrogenation reaction zone comprises multiple partial quench zones.

22. The process according to any of the preceding claims, wherein a final quench is conducted for stabilizing the product gases containing ethylene at a temperature of from 90°C to 150°C.

23. The process according to any of the claims 9 to 22, where the coolant is water or heavy oil or natural gas.

24. The process according to claim 22, wherein the residual acetylene remaining in the final quench product gas together with the unconverted alkane is separated downstream and is recycled back together with the make-up alkane feed to the in situ hydrogenation zone.

25. The process according to claim 23 or 24, wherein the unconverted methane is separated from the final quench product gas downstream and is recycled back to the primary feed with the oxygen or sent to the fuel gas.

26. The process according to claim 12, wherein C3+ un-saturated and aromatic compounds contained in the final effluent gases are separated downstream.

27. The process according to any of the preceding claims, wherein the methane containing feed is natural gas.