Fischer-tropsch catalyst activation procedure
A Fischer-Tropsch catalyst activation system including separation apparatus configured for separating a product gas comprising primarily hydrogen from a gas stream comprising hydrogen, an activation reactor fluidly connected with the separation apparatus via an activation gas inlet line whereby the product gas may be introduced into the activation reactor, and a circulation loop fluidly connecting a gas outlet of the activation reactor with the activation gas inlet line or with another gas inlet of the activation reactor and fluidly connecting the activation reactor with one or more apparatus configured for removal of H 2 O. A method of activating a Fischer-Tropsch catalyst is also provided.
1. A method of activating a Fischer-Tropsch catalyst, the method comprising:
introducing an activation gas into a circulation loop of an activation reactor until a desired activation pressure is attained, wherein the activation gas comprises product gas separated from a gas stream and comprising hydrogen and at least one component selected from the group consisting of carbon monoxide and water vapor,
wherein the activation reactor contains the Fischer-Tropsch catalyst to be activated, and
wherein the circulation loop is configured for recycle exit gas comprising hydrogen to the activation reactor;
circulating gas through the circulation loop and heating the activation reactor to a circulation temperature less than an activation temperature at which the Fischer-Tropsch catalyst is reduced,
whereby at least a portion of any carbon monoxide is converted into an inert component with the production of water vapor, and
wherein circulating gas through the circulation loop comprises removing at least a portion of any H 2 O introduced with the product gas, at least a portion of any H 2 O formed via conversion of carbon monoxide, at least a portion of any H 2 O formed via reduction of catalyst from a higher oxide to a lower oxide, or some combination thereof;
maintaining circulation as a closed loop system;
measuring the concentration of at least one of the carbon monoxide in the closed circulation loop or the H 2 O in the closed circulation loop;
continuing to maintain circulation as a closed loop system until at least one of the measured concentration of carbon monoxide in the closed circulation loop is below a desired CO concentration within a range of from less than about 10 ppmv to less than about 0.1 ppmv or the measured concentration of H 2 O in the closed circulation loop is below a desired H 2 O concentration less than about 100 ppmv; and
raising the temperature of the activation reactor to the activation temperature.
2. The method of claim 1 , wherein the activation gas further comprises at least one component selected from the group consisting of CO 2 , CH 4 and N 2 .
3. The method of claim 1 wherein the product gas comprises less than 99.5 volume percent hydrogen.
4. The method of claim 1 wherein the product gas comprises less than 99 volume percent hydrogen.
5. The method of claim 1 wherein the product gas comprises at least 1 volume percent of one or more non-inert gases other than hydrogen.
6. The method of claim 1 wherein the product gas comprises at least 1 volume percent carbon monoxide.
7. The method of claim 1 wherein the product gas is produced with one or more hydrogen separation membranes.
8. The method of claim 1 wherein, following attainment of the activation pressure, no additional activation gas is introduced into the circulation loop.
9. The method of claim 1 wherein removing at least a portion of any H 2 O comprises reducing the temperature of the gas exiting the activation reactor and separating water therefrom.
10. The method of claim 9 , wherein reducing the temperature of the gas exiting the activation reactor and separating water therefrom comprises introducing the exit gas into a cooler and introducing the cooled gas into a gas/liquid separator, whereby water is separated from a vapor fraction.
11. The method of claim 10 wherein the cooled gas has a temperature of less than or about 4° C.
12. The method of claim 11 wherein the cooled gas has a temperature of less than or about 0° C.
13. The method of claim 10 wherein reducing the temperature of the gas exiting the activation reactor and separating water therefrom further comprises introducing the vapor fraction exiting the gas/liquid separator into a dryer.
14. The method of claim 13 further comprising compressing the vapor fraction prior to introduction thereof into the dryer.
15. The method of claim 14 wherein the dryer comprises a molecular sieve.
16. The method of claim 15 , wherein the molecular sieve is operable to reduce the dew point of the vapor fraction to a value of less than or in the range of from about −20° F. to −30° F.
17. The method of claim 16 wherein the molecular sieve is operable to reduce the water content of the vapor fraction to less than 100 ppmv at 1 atmosphere.
18. The method of claim 17 , wherein the molecular sieve is operable to reduce the water content of the vapor fraction to less than 1 ppmv at 1 atmosphere.
19. The method of claim 1 wherein removing at least a portion of the H 2 O comprises introducing the gas exiting the activation reactor into a dryer.
20. The method of claim 19 , wherein the dryer comprises a molecular sieve capable of reducing the dew points of the gas within the dryer to less than or in the range of from about −20° F. to −30° F.
21. The method of claim 20 , wherein the molecular sieve is operable to reduce the water content of the gas within the dryer to less than 100 ppmv at 1 atmosphere.
22. The method of claim 21 , wherein the molecular sieve is operable to reduce the water content of the gas within the dryer to less than 1 ppmv at 1 atmosphere.
23. The method of claim 19 wherein the dryer comprises a liquid absorber.
24. The method of claim 1 wherein the gas stream comprises synthesis gas suitable for Fischer-Tropsch reactions.
25. The method of claim 1 , wherein the circulation temperature is less than or equal to about 300° C. (572° F.).
26. The method of claim 1 , wherein the activation temperature is in the range of from about 300° C. to about 600° C.
27. The method of claim 26 wherein the activation temperature is in the range of from about 300° C. to about 500° C.
28. The method of claim 27 wherein the activation temperature is in the range of from about 300° C. to about 450° C.
29. The method of claim 1 wherein, prior to raising the temperature of the activation reactor to the activation temperature, the pressure falls less than about 10 psig from the desired activation pressure.
30. The method of claim 1 wherein, prior to raising the temperature of the activation reactor to the activation temperature, the hydrogen purity of the activation gas in the circulation loop is no more than about 9 volume percent less than the hydrogen purity of the product gas.
31. The method of claim 1 further comprising purging a portion of the gas from the circulation loop.
32. The method of claim 1 , wherein the activation reactor is a Fischer-Tropsch synthesis reactor or wherein the activation reactor is a dedicated activation reactor.
33. The method of claim 1 , further comprising maintaining the temperature of the activation reactor at the activation temperature until the catalyst is activated.
34. The method of claim 33 , further comprising producing Fischer-Tropsch hydrocarbons by contacting the activated catalyst with synthesis gas under suitable operating conditions.