Method for activating strengthened iron catalyst for slurry reactors
View Patent ↗A method of activating an iron Fischer-Tropsch catalyst by introducing an inert gas into a reactor comprising a slurry of the catalyst at a first temperature, increasing the reactor temperature from the first temperature to a second temperature at a first ramp rate, wherein the second temperature is in the range of from about 150° C. to 250° C., introducing synthesis gas having a ratio of H 2 :CO to the reactor at a space velocity, and increasing the reactor temperature from the second temperature to a third temperature at a second ramp rate, wherein the third temperature is in the range of from about 270° C. to 300° C. The iron Fischer-Tropsch catalyst may be a precipitated unsupported iron catalyst, production of which is also provided.
1. A method of activating an iron Fischer-Tropsch catalyst, the method comprising:
introducing an inert gas into a reactor comprising a slurry of the catalyst while increasing the reactor temperature from a first temperature to a second temperature at a first ramp rate, wherein the second temperature is in the range of from about 150° C. to 250° C.; and
subsequently introducing synthesis gas having a ratio of H 2 :CO to the reactor while increasing the reactor temperature from the second temperature to a third temperature at a second ramp rate, wherein the third temperature is in the range of from about 270° C. to 300° C.
2. The method of claim 1 further comprising maintaining the reactor pressure in the range of from about 0 psig to about 175 psig during activation.
3. The method of claim 2 wherein the pressure is maintained in the range of from about 30 psig to about 140 psig during activation.
4. The method of claim 1 wherein the first ramp rate is in the range of from about 1° C./min to 5° C./min.
5. The method of claim 1 wherein the second ramp rate is in the range of from about 0.2° C./min to 1° C./min.
6. The method of claim 1 wherein the synthesis gas is introduced to the reactor at a space velocity in the range of from about 3 to about 4 normal liters per hour per gram Fe.
7. The method of claim 1 wherein the ratio of H 2 :CO is in the range of from about 0.5 to 1.5.
8. The method of claim 1 wherein the second temperature is about 150° C.
9. The method of claim 1 wherein the third temperature is about 270° C.
10. The method of claim 1 wherein the iron Fischer-Tropsch catalyst is a precipitated unsupported iron catalyst.
11. The method of claim 10 wherein the catalyst comprises a structural promoter introduced during catalyst formation as at least one selected from the group consisting of potassium silicate, TEOS, and silica.
12. The method of claim 11 wherein the iron Fischer-Tropsch catalyst comprises greater than 3% structural promoter, and wherein the ratio of H 2 :CO is less than about 1.
13. The method of claim 10 further comprising producing the precipitated unsupported iron catalyst by:
precipitating a catalyst precursor comprising at least one iron phase selected from iron hydroxides and iron carbonates;
adding a promoter to the catalyst precursor to yield a promoted precursor;
drying the promoted precursor to yield dried catalyst; and
calcining the dried catalyst,
wherein the catalyst further comprises copper and potassium.
14. The method of claim 13 wherein the promoter comprises potassium silicate structural promoter.
15. The method of claim 14 wherein the dried catalyst comprises from about 1 wt % SiO 2 to about 2.2 wt % SiO 2 .
16. The method of claim 13 further comprising adding potassium carbonate to the catalyst precursor in an amount sufficient to promote the catalyst with potassium.
17. The method of claim 13 wherein the catalyst precursor further comprises copper oxide.
18. The method of claim 13 further comprising adding copper nitrate to the catalyst precursor.
19. The method of claim 13 wherein the promoter comprises TEOS structural promoter.
20. The method of claim 13 wherein precipitating a catalyst precursor comprises precipitating iron hydroxide, iron carbonate, or a mixture thereof from a solution comprising TEOS or potassium silicate, and adding a promoter to the catalyst precursor to yield a promoted precursor comprises adding potassium carbonate.
21. The method of claim 13 wherein the promoter comprises colloidal silica as structural promoter.
22. The method of claim 1 wherein the iron Fischer-Tropsch catalyst comprises about 1 weight percent copper.
23. The method of claim 1 wherein the iron Fischer-Tropsch catalyst comprises about 1 weight percent potassium.
24. The method of claim 1 wherein the catalyst has an Fe:Cu mass ratio in the range of from about 100:1 to about 100:7.
25. The method of claim 24 wherein the catalyst has an Fe:Cu mass ratio of about 100:4.
26. The method of claim 25 wherein the catalyst has an Fe:Cu:K:SiO 2 mass ratio of about 100:4:3:5.
27. The method of claim 25 wherein the catalyst has an Fe:Cu:K:SiO 2 mass ratio of about 100:3:3:5.
28. The method of claim 1 wherein the catalyst has an Fe:K mass ratio in the range of from about 100:1 to about 100:5.
29. The method of claim 28 wherein the catalyst has an Fe:K mass ratio of about 100:3.
30. The method of claim 1 wherein the catalyst has an Fe:SiO 2 mass ratio in the range of from about 100:1 to about 100:8.
31. The method of claim 30 wherein the catalyst has an Fe:SiO 2 mass ratio of about 100:5.
32. The method of claim 1 wherein the inert gas comprises nitrogen.