Bifunctional catalysts and systems and methods for oxidative dehydrogenation of alkanes to olefins and high-valued products
Bifunctional catalyst compositions, methods, and systems are provided for the use of CO 2 as a soft oxidizing agent to effectively convert low-value small alkanes to high-value small olefins. The bifunctional catalyst comprises a metal oxide catalyst and a redox-active ceramic support.
1. A bifunctional oxidative dehydrogenation catalyst comprising a metal oxide and a redox active ceramic support, wherein the redox active ceramic support promotes a water-gas shift process, and wherein the redox active ceramic support comprises a doped perovskite ceramic.
2. The bifunctional oxidative dehydrogenation catalyst according to claim 1 , wherein the metal oxide is selected from the group consisting of Cr 2 O 3 , V 2 O 5 , In 2 O 3 , Fe 2 O 3 , and combinations thereof, and wherein the metal oxide is mixed with or impregnated in the redox active ceramic support.
3. The bifunctional oxidative dehydrogenation catalyst according to claim 1 , wherein the redox active ceramic support comprises one or more of Al 2 O 3 , Ce 2 O 3 , ZrO 2 , BaCe 0.7 Zr 0.1 Y 0.1 Yb 0.1 O 2.95 , and BaZr 1-x Y x O 3-δ (0≤x≤0.20).
4. The bifunctional oxidative dehydrogenation catalyst according to claim 1 , wherein the metal oxide promotes alkane dehydrogenation via a Mars van Krevelen process with carbon dioxide as an oxidant.
5. A method for alkane dehydrogenation, comprising:
providing a catalytic membrane reactor comprising a catalyst bed and a hydrogen selective membrane, wherein the catalyst bed comprises a bifunctional catalyst comprising a metal oxide and a redox active ceramic support, and wherein the redox active ceramic support comprises a doped perovskite ceramic,
contacting an input gas stream comprising at least one alkane and carbon dioxide with the bifunctional catalyst to form a product gas stream comprising at least one olefin and hydrogen, and
separating the hydrogen from the product gas stream.
6. The method according to claim 5 , wherein the metal oxide is selected from the group consisting of Cr 2 O 3 , V 2 O 5 , In 2 O 3 , Fe 2 O 3 , and combinations thereof, and wherein the metal oxide is mixed with or impregnated in the redox active ceramic support.
7. The method according to claim 5 , wherein the redox active ceramic support comprises one or more of Al 2 O 3 , Ce 2 O 3 , ZrO 3 , BaCe 0.7 Zr 0.1 Y 0.1 Yb 0.1 O 2.95 , and BaZr 1-x Y x O 3-δ (0≤x≤0.20).
8. The method according to claim 5 , wherein the at least one alkane comprises ethane, propane, butane, or mixtures thereof.
9. The method according to claim 5 , wherein alkane dehydrogenation occurs at least partially via a Mars van Krevelen process and wherein a water-gas shift process forms at least some of the carbon dioxide.
10. The method according to claim 5 , wherein a molar ratio of the at least one alkane to carbon dioxide in the input gas stream is greater than 1.
11. The method according to claim 5 , wherein the contacting step occurs at a temperature from about 450° C. to about 650° C.
12. The method according to claim 5 , wherein the hydrogen selective membrane comprises a material selected from the group consisting of a metal, a ceramic, a polymer, and combinations thereof.
13. The method according to claim 5 , wherein a rate of olefin production is about 1.0×10 −2 mol gcat −1 h −1 or more.
14. A catalytic membrane reactor comprising:
a. a bifunctional catalyst comprising a metal oxide and a redox active ceramic support, wherein the redox active ceramic support comprises a doped perovskite ceramic; and
b. a hydrogen selective membrane,
wherein the bifunctional catalyst is contained in a catalyst bed that is at least partially enclosed by the hydrogen selective membrane.
15. The catalytic membrane reactor of claim 14 , wherein the hydrogen selective membrane comprises a material selected from the group consisting of a metal, a ceramic, a polymer, and combinations thereof.
16. The catalytic membrane reactor of claim 14 , wherein the metal oxide is selected from the group consisting of Cr 2 O 3 , V 2 O 5 , In 2 O 3 , Fe 2 O 3 , and combinations thereof, and wherein the metal oxide is mixed with or impregnated in the redox active ceramic support.
17. The catalytic membrane reactor of claim 14 , wherein the redox active ceramic support comprises one or more of Al 2 O 3 , Ce 2 O 3 , and ZrO 2 .
18. The catalytic membrane reactor of claim 14 , further comprising an input gas stream and first and second output gas streams, the input gas stream comprising carbon dioxide and at least one alkane, the first output gas stream comprising at least one olefin, and the second output gas stream comprising hydrogen.