Process for preparing an iron-chromium catalyst with a platinum promoter, and catalyst consisting of iron chromium with a platinum promoter
The present invention relates to catalysts of iron and chromium with a platinum promoter for use in water-gas shift reactions, both at low temperatures (LTS) and at high temperatures (HTS). Their characteristics of higher activity due to the addition of Pt compared to the conventional catalysts make them superior to the commercial catalysts in the same operating conditions. Because precursors of the active phase (Fe 3 O 4 ) are obtained in greater quantity per unit area, it was possible to prepare catalysts that are more promising with a smaller surface area.
1. A process for preparing an iron-chromium water-gas shift reaction catalyst with a platinum promoter, wherein the process consists of the following steps:
(a) synthesizing iron and chromium oxides by a method of co-precipitation so as to obtain Fe 2 O 3 and Cr 2 O 3 ; and
(b) adding platinum to the catalyst obtained in (a),
wherein the process excludes addition of oxides other than iron and chromium oxide.
2. The process according to claim 1 , wherein the co-precipitation provides Fe 2 O 3 and Cr 2 O 3 in a ratio of 85-95%:15-5% by weight.
3. The process according to claim 1 , wherein the platinum is added in an amount of from 0.01 to 1.5 wt% of the catalyst.
4. The process according to claim 1 , wherein the platinum is added by a method of dry impregnation of the catalyst.
5. The process according to claim 1 , wherein the iron and chromium oxides are synthesized from Fe(NO 3 ) 3 0.9H 2 0 and Cr(NO 3 ) 3 0.9H 2 O, respectively.
6. The process according to claim 5 , wherein the iron and chromium oxides are synthesized at a temperature from 60 to 80° C.
7. The process according to claim 5 , wherein a base is added to the solution of Fe(NO 3 ) 3 0.9H 2 O and Cr(NO 3 ) 3 0.9H 2 O in the step of synthesis of the iron and chromium oxides.
8. The process according to claim 7 , wherein the base is Na 2 CO 3 .
9. The process according to claim 7 , wherein the iron-chromium catalyst is matured in the solution containing the base for 1 to 10 hours prior to the step of adding platinum to the catalyst.
10. The process according to claim 1 , wherein the addition of the platinum comprises the addition of hexachloroplatinic acid as a platinum precursor.
11. A catalyst consisting of iron-chromium with a platinum promoter prepared by the process as defined in claim 1 ,
wherein the catalyst has a specific surface area between 35 and 45 m 2 .g −1 .
12. The catalyst according to claim 11 , wherein the catalyst is used in water-gas shift reactions in both low-temperature shift and high-temperature shift.
13. The catalyst according to claim 11 , wherein the catalyst is used in water-gas shift reactions in the temperature range of from 200 to 450° C.
14. The process according to claim 1 , wherein the iron-chromium catalyst is filtered and dried for 10-14 hours at 100-120° C. prior to the step of adding platinum to the catalyst.
15. A process for preparing an iron-chromium water-gas shift reaction catalyst with a platinum promoter, wherein the process consists of the following steps:
(a) synthesizing iron and chromium oxides by a method of co-precipitation so as to obtain Fe 2 O 3 and Cr 2 O 3 ;
(b) adding platinum to the catalyst obtained in (a), and
(c) drying at a temperature from 110 to 130° C., wherein the process excludes addition of oxides other than iron and chromium oxide.
16. The process according to claim 15 , wherein the step of drying is performed for 20 to 28 hours.
17. A process for preparing an iron-chromium water-gas shift reaction catalyst with a platinum promoter, wherein the process consists of the following steps:
(a) synthesizing iron and chromium oxides by a method of co-precipitation so as to obtain Fe 2 O 3 and Cr 2 O 3 ;
(b) adding platinum to the catalyst obtained in (a), and
calcinating the catalyst,
wherein the process excludes addition of oxides other than iron and chromium oxide.
18. The process according to claim 17 , wherein the step of calcination is performed at a temperature of from 440 to 460° C.
19. The process according to claim 18 , wherein the step of calcination comprises maintaining the temperature between 440 and 460° C. for 1 to 3 hours.
20. The process according to claim 19 , wherein the step of calcination comprises an initial heating step, heating at a rate of from 5 to 15° C./min, to reach the temperature of from 440 to 460° C.