Nanowire catalysts and methods for their use and preparation
Nanowires useful as heterogeneous catalysts are provided. The nanowire catalysts are useful in a variety of catalytic reactions, for example, the oxidative coupling of methane to C2 hydrocarbons. Related methods for use and manufacture of the same are also disclosed.
1. A catalytic material in the form of a pressed pellet, extrudate or monolith, the catalytic material comprising:
a) a plurality of catalytic nanowires, the catalytic nanowires comprising one or more doping elements; and
b) a diluent or support selected from one or more alkaline earth metal compounds,
wherein the catalytic material has a C2+ yield above 5% when employed as catalytic material in the oxidative coupling of methane at an inlet temperature of 550° C. and an inlet pressure of 2 atm in a fixed bed reactor with a gas-hour space velocity (GHSV) of at least about 20,000/hr.
2. The catalytic material of claim 1 , wherein the alkaline earth metal compound is an alkaline earth metal oxide, alkaline earth metal carbonate, alkaline earth metal sulfate or alkaline earth metal phosphate.
3. The catalytic material of claim 1 , wherein the alkaline earth metal compound is an alkaline earth metal carbonate, alkaline earth metal sulfate or alkaline earth metal phosphate.
4. The catalytic material of claim 1 , wherein the alkaline earth metal compound is MgO, MgCO3, MgSO4, Mg3(PO4)2, MgAl2O4, CaO, CaCO3, CaSO4, Ca3(PO4)2, CaAl2O4, SrO, SrCO3, SrSO4, Sr3(PO4)2, SrAl2O4, BaO, BaCO3, BaSO4, Ba3(PO4)2, BaAl2O4 or combinations thereof.
5. The catalytic material of claim 1 , wherein the alkaline earth metal compound is MgCO3, MgSO4, Mg3(PO4)2, CaO, CaCO3, CaSO4, Ca3(PO4)2, CaAl2O4, SrO, SrCO3, SrSO4, Sr3(PO4)2, SrAl2O4, BaO, BaCO3, BaSO4, Ba3(PO4)2, BaAl2O4 or combinations thereof.
6. The catalytic material of claim 1 , wherein the alkaline earth metal compound is CaO, SrO, MgCO3, CaCO3, SrCO3 or combinations thereof.
7. The catalytic material of claim 1 , wherein the plurality of catalytic nanowires have a ratio of average effective length to average actual length of less than one and an average aspect ratio of greater than ten as measured by TEM in bright field mode at 5 keV, wherein the plurality of catalytic nanowires comprises one or more elements from any of Groups 1 through 7, lanthanides, actinides or combinations thereof.
8. The catalytic material of claim 1 , wherein the plurality of catalytic nanowires comprises substantially straight nanowires.
9. The catalytic material of claim 8 , wherein the substantially straight nanowires have a ratio of effective length to actual length equal to one.
10. The catalytic material of claim 1 , wherein the plurality of catalytic nanowires comprises at least one nanowire selected from any one of Tables 1-12.
11. The catalytic material of claim 1 , wherein the catalytic material has a C2 selectivity above 50% when employed as catalytic material in the oxidative coupling of methane at an inlet temperature of 550° C. and an inlet pressure of about 2 atm in a fixed bed reactor with a gas-hour space velocity (GHSV) of at least about 20,000/hr.
12. The catalytic material of claim 1 , wherein the catalytic material has a CH4 conversion above 20% when employed as catalytic material in the oxidative coupling of methane at an inlet temperature of 550° C. and an inlet pressure of about 2 atm in a fixed bed reactor with a gas-hour space velocity (GHSV) of at least about 20,000/hr.
13. The catalytic material of claim 1 , wherein the catalytic material further comprises SiC or cordierite or combinations thereof.
14. The catalytic material of claim 1 , further comprising a sacrificial binder.
15. The catalytic material of claim 14 , wherein the sacrificial binder comprises silica sold under the trademark LUDOX or colloidal zirconia sold under the trademark NYACOL.
16. The catalytic material of claim 14 , wherein the alkaline earth metal compound is MgO, MgCO3, MgSO4, Mg3(PO4)2, MgAl2O4, CaO, CaCO3, CaSO4, Ca3(PO4)2, CaAl2O4, SrO, SrCO3, SrSO4, Sr3(PO4)2, SrAl2O4, BaO, BaCO3, BaSO4, Ba3(PO4)2, BaAl2O4 or combinations thereof.
17. The catalytic material of claim 16 , wherein the alkaline earth metal compound is MgO, CaO, SrO, MgCO3, CaCO3, SrCO3 or combinations thereof.
18. The catalytic material of claim 14 , wherein the plurality of catalytic nanowires have a ratio of average effective length to average actual length of less than one and an average aspect ratio of greater than ten as measured by TEM in bright field mode at 5 keV, wherein the plurality of catalytic nanowires comprises one or more elements from any of Groups 1 through 7, lanthanides, actinides or combinations thereof.
19. The catalytic material of claim 14 , wherein the plurality of catalytic nanowires comprises substantially straight nanowires.
20. The catalytic material of claim 19 , wherein the substantially straight nanowires have a ratio of effective length to actual length equal to one.
21. The catalytic material of claim 14 , wherein the plurality of catalytic nanowires comprises at least one nanowire selected from any one of Tables 1-12.
22. The catalytic material of claim 14 , wherein the catalytic material further comprises SiC or cordierite or combinations thereof.
23. The catalytic material of claim 1 , wherein the catalytic material is in the form of a pressure treated, pressed pellet and comprises substantially no binder material.
24. The catalytic material of claim 23 , wherein the plurality of catalytic nanowires have a ratio of average effective length to average actual length of less than one and an average aspect ratio of greater than ten as measured by TEM in bright field mode at 5 keV, wherein the plurality of catalytic nanowires comprises one or more elements from any of Groups 1 through 7, lanthanides, actinides or combinations thereof.
25. The catalytic material of claim 23 , wherein the plurality of catalytic nanowires comprises substantially straight nanowires.
26. The catalytic material of claim 25 , wherein the substantially straight nanowires have a ratio of effective length to actual length equal to one.
27. The catalytic material of claim 23 , wherein the plurality of catalytic nanowires comprises at least one nanowire selected from any one of Tables 1-12.
28. The catalytic material of claim 23 , wherein the alkaline earth metal compound is an alkaline earth metal oxide, alkaline earth metal carbonate, alkaline earth metal sulfate or alkaline earth metal phosphate.
29. The catalytic material of claim 28 , wherein the alkaline earth metal compound is MgO, MgCO3, MgSO4, Mg3(PO4)2, MgAl2O4, CaO, CaCO3, CaSO4, Ca3(PO4)2, CaAl2O4, SrO, SrCO3, SrSO4, Sr3(PO4)2, SrAl2O4, BaO, BaCO3, BaSO4, Ba3(PO4)2, BaAl2O4 or combinations thereof.
30. The catalytic material of claim 29 , wherein the alkaline earth metal compound is MgO, CaO, SrO, MgCO3, CaCO3, SrCO3 or combinations thereof.
31. The catalytic material of claim 23 , wherein the catalytic material has a C2 selectivity above 50% when employed as catalytic material in the oxidative coupling of methane at an inlet temperature of 550° C. and an inlet pressure of about 2 atm in a fixed bed reactor with a gas-hour space velocity (GHSV) of at least about 20,000/hr.
32. The catalytic material of claim 23 , wherein the catalytic material has a CH4 conversion above 20% when employed as catalytic material in the oxidative coupling of methane at an inlet temperature of 550° C. and an inlet pressure of about 2 atm in a fixed bed reactor with a gas-hour space velocity (GHSV) of at least about 20,000/hr.
33. The catalytic material of claim 23 , wherein the catalytic material further comprises SiC or cordierite or combinations thereof.
34. The catalytic material of claim 1 , wherein the catalytic material is in the form of a pressed pellet or extrudate, and comprises pores greater than 20 nm in diameter.
35. The catalytic material of claim 34 , wherein the plurality of catalytic nanowires have a ratio of average effective length to average actual length of less than one and an average aspect ratio of greater than ten as measured by TEM in bright field mode at 5 keV, wherein the plurality of catalytic nanowires comprises one or more elements from any of Groups 1 through 7, lanthanides, actinides or combinations thereof.
36. The catalytic material of claim 34 , wherein the plurality of catalytic nanowires comprises substantially straight nanowires.
37. The catalytic material of claim 36 , wherein the substantially straight nanowires have a ratio of effective length to actual length equal to one.
38. The catalytic material of claim 34 , wherein the plurality of catalytic nanowires comprises at least one nanowire selected from any one of Tables 1-12.
39. The catalytic material of claim 34 , wherein the catalytic material has a C2 selectivity above 50% when employed as catalytic material in the oxidative coupling of methane at an inlet temperature of 550° C. and an inlet pressure of about 2 atm in a fixed bed reactor with a gas-hour space velocity (GHSV) of at least about 20,000/hr.
40. The catalytic material of claim 34 , wherein the catalytic material has a CH4 conversion above 20% when employed as catalytic material in the oxidative coupling of methane at an inlet temperature of 550° C. and an inlet pressure of about 2 atm in a fixed bed reactor with a gas-hour space velocity (GHSV) of at least about 20,000/hr.
41. The catalytic material of claim 34 , wherein the alkaline earth metal compound is an alkaline earth metal oxide, alkaline earth metal carbonate, alkaline earth metal sulfate or alkaline earth metal phosphate.
42. The catalytic material of claim 41 , wherein the alkaline earth metal compound is MgO, MgCO3, MgSO4, Mg3(PO4)2, MgAl2O4, CaO, CaCO3, CaSO4, Ca3(PO4)2, CaAl2O4, SrO, SrCO3, SrSO4, Sr3(PO4)2, SrAl2O4, BaO, BaCO3, BaSO4, Ba3(PO4)2, BaAl2O4 or combinations thereof.
43. The catalytic material of claim 42 , wherein the alkaline earth metal compound is MgO, CaO, SrO, MgCO3, CaCO3, SrCO3 or combinations thereof.
44. The catalytic material of claim 34 , wherein the catalytic material further comprises SiC or cordierite or combinations thereof.