Removal of catalyst fines from a reaction system

Abstract

This invention provides a process for limiting the loss of catalyst particles through olefin product streams and regenerator flue gas streams exiting the reaction system. In particular, this invention provides for removing catalyst particles from the reactor using a water stream and from the regenerator using a two step separation process. The two step process involves the use of a catalyst fine separation unit.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

Examples of the invention are provided with reference to the attached Figures, wherein

FIG. 1 shows a flow diagram of the invention in which a filter and/or electrostatic precipitator is used as catalyst fine separation unit;

FIG. 2 shows a flow diagram of the invention in which a wet electrostatic precipitator is used as catalyst fine separation unit;

FIG. 3 shows a flow diagram of the invention in which a wet gas scrubber is used as catalyst fine separation unit; and

FIG. 4 is a graph comparing the resistivities of certain molecular sieve catalysts.

Claims

1. A process for removing molecular sieve catalyst particles containing [AlO4] and [SiO4] tetrahedral units from an oxygenate to olefin reaction system having a reactor and regenerator, comprising: a) separating the molecular sieve catalyst particles from a flue gas stream in the regenerator so that the flue gas stream exits the regenerator at an average catalyst loading of greater than or equal to 10 mg/NM3; andb) flowing the flue gas stream exiting the regenerator through a catalyst fine separation unit to form a final flue gas stream having an average catalyst loading of less than that of the stream exiting the regenerator.

2. The process of claim 1, wherein the catalyst is separated in the regenerator using a cyclone separation system.

3. The process of claim 1, wherein the catalyst fine separation unit is an electrostatic precipitator.

4. The process of claim 3, wherein the electrostatic precipitator is operated at a temperature of at least 250° C.

5. The process of claim 3, wherein the electrostatic precipitator is operated at a catalyst resistivity of not greater than 1012 ohm-cm.

6. The process of claim 3, wherein the molecular sieve catalyst comprises an electrostatic charging modifier that provides a catalyst resistivity of not greater than 1012 ohm-cm.

7. The process of claim 6, wherein the electrostatic charging modifier includes at least one metal oxide and the catalyst particles have a TOFredox of not greater than 1000 sec−1, measured at 100° C.

8. The process of claim 6, wherein the electrostatic charging modifier is selected from the group consisting of Cr2O3, V2O5, Fe2O3, NiO, ZnO, SnO2, MoO3, TeO2, Sb2O3, ZrO2, and CeO2.

9. The process of claim 3, wherein the molecular sieve catalyst comprises at least one metal oxide electrostatic charging modifier in an amount of at least 50 ppm, based on total weight of the catalyst.

10. The process of claim 3, wherein a gas stream is added to the electrostatic precipitator to provide a catalyst resistivity of not greater than 1012 ohm-cm.

11. The process of claim 3, wherein a water stream is added to the electrostatic precipitator and the electrostatic precipitator is operated at water dew point temperature.

12. The process of claim 1, wherein the catalyst fine separation unit is a filter unit and the filter unit is operated at an average temperature of from 100° C. to 450° C.

13. The process of claim 1, wherein the catalyst fine separation unit is a wet gas scrubber in which a water stream is injected into the scrubber to remove the catalyst particles and form the final flue gas stream.

14. The process of claim 13, wherein the water stream is taken from a bottoms stream of a methanol stripper.

15. The process of claim 1, wherein the process further comprises contacting the catalyst particles with an oxygenate stream in the reactor to form an olefin product, and contacting the olefin product with a water stream in a quench column to remove catalyst particles entrained in the olefin product.

16. The process of claim 15, wherein a water stream containing catalyst particles is removed from the quench column and sent to a methanol stripper.

17. The process of claim 16, wherein at least a portion of a bottoms water stream from the methanol stripper is sent to the fine separation unit.

18. A process for removing molecular sieve catalyst particles containing [AlO4] and [SiO4] tetrahedral units from an oxygenate to olefin reaction system having a reactor and regenerator, comprising: a) separating at least a portion of the catalyst particles from a flue gas stream in the regenerator so that the flue gas stream exits the regenerator at an average catalyst loading of from 10 mg/NM3 to 200 mg/NM3;b) flowing the flue gas stream exiting the regenerator through an electrostatic precipitator operated at a catalyst resistivity of not greater than 1012 ohm-cm; andc) recovering a final flue gas stream from the electrostatic precipitator having an average catalyst loading less than that of the flue gas stream from the regenerator.

19. The process of claim 18, wherein the electrostatic precipitator is operated to produce a final flue gas having an average catalyst loading of less than 10 mg/NM3.

20. The process of claim 18, wherein the catalyst is separated in the regenerator using a cyclone separation system.

21. The process of claim 18, wherein the molecular sieve catalyst comprises an electrostatic charging modifier that provides a catalyst resistivity of not greater than 1012 ohm-cm.

22. The process of claim 21, wherein the electrostatic charging modifier is selected from the group consisting of Cr2O3, V2O5, Fe2O3, NiO, ZnO, SnO2, MoO3, TeO2, Sb2O3, ZrO2, and CeO2.

23. The process of claim 18, wherein a gas stream is added to the electrostatic precipitator to provide a catalyst resistivity of not greater than 1012 ohm-cm.

24. The process of claim 18, wherein a water stream is added to the electrostatic precipitator and the electrostatic precipitator is operated at water dew point temperature.

25. The process of claim 18, wherein the process further comprises contacting the catalyst particles with an oxygenate stream in the reactor to form an olefin product, and contacting the olefin product with a water stream in a quench column to remove catalyst particles entrained in the olefin product.

26. The process of claim 25, wherein a water stream containing catalyst particles is removed from the quench column and sent to a methanol stripper.

27. The process of claim 25, wherein at least a portion of a bottoms water stream from the methanol stripper is sent to the fine separation unit.

28. A process for removing molecular sieve catalyst particles containing [AlO4] and [SiO4] tetrahedral units from an oxygenate to olefin reaction system having a reactor and regenerator, comprising: a) contacting the catalyst particles with an oxygenate stream in the reactor to form an olefin product;b) contacting the olefin product with a water stream in a quench column to remove catalyst particles entrained in the olefin product;c) separating at least a portion of the catalyst particles from a flue gas stream in the regenerator so that the flue gas stream exits the regenerator at an average catalyst loading of from 10 mg/NM3 to 200 mg/NM3;d) flowing the flue gas stream exiting the regenerator through a catalyst fine separation unit; ande) recovering a final flue gas stream from the catalyst fine separation unit at an average catalyst loading less than that of the flue gas stream from the regenerator.

29. The process of claim 28, wherein the catalyst fine separation unit is operated to produce a final flue gas having an average catalyst loading of less than 10 mg/NM3.

30. The process of claim 28, wherein the catalyst is separated in the regenerator using a cyclone separation system.

31. The process of claim 28, wherein the catalyst fine separation unit is an electrostatic precipitator.

32. The process of claim 31, wherein the electrostatic precipitator is operated at a temperature of at least 700° C.

33. The process of claim 31, wherein the electrostatic precipitator is operated at a catalyst resistivity of not greater than 1012 ohm-cm.

34. The process of claim 31, wherein the molecular sieve catalyst comprises an electrostatic charging modifier that provides a catalyst resistivity of not greater than 1012 ohm-cm.

35. The process of claim 34, wherein the electrostatic charging modifier is selected from the group consisting of Cr2O3, V2O5, Fe2O3, NiO, ZnO, SnO2, MoO3, TeO2, Sb2O3, ZrO2, and CeO2.

36. The process of claim 31, wherein a gas stream is added to the electrostatic precipitator to provide a catalyst resistivity of not greater than 1012 ohm-cm.

37. The process of claim 31, wherein a water stream is added to the electrostatic precipitator and the electrostatic precipitator is operated at water dew point temperature. (ESP4 and 5; preferably at a temperature of not greater than 100° C. for water vapor stream).

38. The process of claim 28, wherein the catalyst fine separation unit is a filter unit and the filter unit is operated at an average temperature of from 100° C. to 450° C.

39. The process of claim 28, wherein the catalyst fine separation unit is a wet gas scrubber in which a water stream is injected into the scrubber to remove the catalyst particles and form the final flue gas stream.

40. The process of claim 39, wherein the water stream is taken from a bottoms stream of a methanol stripper.