Supported perovskite-oxide composites for enhanced low temperature thermochemical conversion of CO
Disclosed herein is a catalyst composite containing a perovskite-oxide and an oxide support, methods of preparing a catalyst composite containing a perovskite-oxide and an oxide support, and the use thereof for CO 2 conversion by a reverse water gas shift chemical looping (RWGS-CL) process.
1. A catalyst composite comprising:
a perovskite-oxide of formula ABO 3 , wherein A has a formula of La x Sr y , and B is a transitional metal element, metal element, or a combination thereof; and
an oxide support having a formula different from the perovskite-oxide;
wherein x is 0-1, y is 0-1, and the sum of x and y is 1; and wherein the perovskite-oxide crystallite size is between 5 and 100 nm.
2. The catalyst composite of claim 1 , wherein oxide support increases the perovskite-oxide surface area and wherein the perovskite-oxide surface area is between 1 and 1000 m 2 /g.
3. The catalyst composite of claim 1 , wherein the perovskite-oxide crystallite size is between 30 and 100 nm.
4. The catalyst composite of claim 1 , wherein
x is 0.2-0.8; and
y is 0.2-0.8.
5. The catalyst composite of claim 1 , wherein B is selected from the group consisting of Fe, Ti, Y, Mn, Al, Cr, Co, Ta, Ni, and Ce, or a combination thereof.
6. The catalyst composite of claim 1 , wherein the perovskite-oxide is La 0.75 Sr 0.25 FeO 3 .
7. The catalyst composite of claim 1 , wherein the oxide support is CeO 2 , ZrO 2 , Al 2 O 3 , SiO 2 , TiO 2 , or a combination thereof.
8. The catalyst composite of claim 1 , wherein a weight ratio of the perovskite-oxide to the oxide support is from 10:90 to 90:10.
9. A method of preparing the catalyst composite of claim 1 , comprising:
(a) mixing the perovskite-oxide of formula ABO 3 with the oxide support having a formula different from the perovskite-oxide to form a mixture, wherein B is a transitional metal element, a metal element, or a combination thereof; and
(b) heating the mixture to a temperature of between 600° C. and 1300° C.
10. The method of claim 9 , wherein B is selected from the group consisting of Fe, Ti, Y, Mn, Al, Cr, Co, Ta, Ni, and Ce, or a combination thereof.
11. The method of claim 9 , wherein the perovskite-oxide is La 0.75 Sr 0.25 FeO 3 .
12. The method of claim 9 , wherein the oxide support is CeO 2 , ZrO 2 , Al 2 O 3 , SiO 2 , TiO 2 , or a combination thereof.
13. The method of claim 9 , wherein the weight ratio of the perovskite-oxide to the oxide support is from 10:90 to 90:10.
14. The method of claim 9 , wherein
the oxide support comprises M 2 , wherein M 2 is an element other than 0; and
the perovskite-oxide and the oxide support form a secondary phase having a formula of M 1 p M 2 q O v , wherein
M 1 is the A or B component of the perovskite-oxide;
p is 1-3;
q is 1-3; and v is 2-7.
15. A method for converting CO 2 to CO comprising:
(a) contacting H 2 with the catalyst composite of claim 1 , whereby the perovskite oxide is reduced, and whereby H 2 is oxidized to produce H 2 O; and
(b) contacting CO 2 with the catalyst composite, whereby the reduced perovskite oxide is oxidized, and whereby CO 2 is reduced to produce CO.
16. The method of claim 15 , wherein each of step (a) and step (b) is carried out isothermally at a temperature between 450° C. and 800° C.
17. The method of claim 15 , wherein the temperature of step (a) is between 400° C. and 850° C., or wherein the temperature of step (b) is between 450° C. and 900° C.
18. The method of claim 15 , wherein CO is produced at a rate of 0.5 to 1 mmol CO/g perovskite-oxide/min.
19. The method of claim 15 , further comprising repeating step (a) and step (b) in succession.