Heterogeneous catalysts
Heterogeneous catalysts with optional dopants are provided. The catalysts are useful in a variety of catalytic reactions, for example, the oxidative coupling of methane to C 2+ hydrocarbons. Related methods for use and manufacture of the same are also disclosed.
1. A catalyst comprising a mixed oxide base material for the oxidative coupling of methane, the mixed oxide base material comprising lanthanide elements and a dopant combination selected from the group consisting of Sr/Sm, Sr/Gd, Sr/Dy, Sr/Er, Sr/Lu, Sr/Ba/B, Ba/B, Ba/Sr, Er/W, Sr/K, Ba/Ce, Ba/Hf, Ga/Mg, Mg/Er, Y/Ba, Sr/Ga/Mg, Sr/Y, Sr/B/Y, Ca/B, Sr/Al, Ba/W, B/W, Sr/Ba/W, Sr/W/B, Ba/W/B and Sr/Ba/WB,
wherein the mixed oxide base material has the following formula (III):
Ln1 a Ln2 b Ln3 d Ln4 e Ln5 f O c (III)
wherein:
Ln1, Ln2, Ln3, Ln4 and Ln5 are independently different lanthanide elements;
O is oxygen; and
a, b and c are each independently numbers greater than 0; and
d, e and f are independently 0 or a number greater than 0,
provided that one of the lanthanide elements is not lanthanum when another lanthanide element is neodymium.
2. The catalyst of claim 1 , wherein:
a, b, c and d are each independently numbers greater than 0; and
e and f are independently 0 or a number greater than 0.
3. The catalyst of claim 1 , wherein the catalyst is a nanowire catalyst.
4. The catalyst of claim 1 , further comprising an alkaline earth metal diluent.
5. The catalyst of claim 1 , wherein the catalyst exhibits a C 2 + selectivity of greater than 50% and a methane conversion of greater than 20% when the catalyst is employed as a heterogeneous catalyst in the oxidative coupling of methane at a temperature of 750° C. or less.
6. The catalyst of claim 1 , in combination with a support material.
7. A method for conversion of methane to C 2 + hydrocarbons, the method comprising contacting the catalyst of claim 1 with methane and an oxidant source.
8. The catalyst of claim 1 , wherein Ln1 is Gd.
9. The catalyst of claim 1 , wherein Ln2 is Nd.
10. The catalyst of claim 1 , wherein at least one lanthanide element is erbium (Er).
11. The catalyst of claim 10 , wherein the mixed oxide base material comprises a physical blend of Er, or an oxidized form thereof, and a further lanthanide element, or an oxidized form thereof.
12. The catalyst of claim 1 , further comprising a support, diluent, binder, or combinations thereof.
13. The catalyst of claim 1 , in the form of a pellet or extrudate.
14. A catalyst comprising a mixed oxide base material for the oxidative coupling of methane, the mixed oxide base material comprising three different lanthanide elements and a dopant combination selected from the group consisting of Sr/Sm, Sr/Gd, Sr/Dy, Sr/Er, Sr/Lu, Sr/Ba/B, Ba/B, Ba/Sr, Er/W, Sr/K, Ba/Ce, Ba/Hf, Ga/Mg, Mg/Er, Y/Ba, Sr/Ga/Mg, Sr/Y, Sr/B/Y, Ca/B, Sr/Al, Ba/W, B/W, Sr/Ba/W, Sr/W/B, Ba/W/B and Sr/Ba/W/B, provided that one of the lanthanide elements is not lanthanum when another lanthanide element is neodymium.
15. The catalyst of claim 14 , wherein the catalyst is a nanowire catalyst.
16. The catalyst of claim 14 , further comprising an alkaline earth metal diluent.
17. The catalyst of claim 14 , wherein the catalyst exhibits a C 2 + selectivity of greater than 50% and a methane conversion of greater than 20% when the catalyst is employed as a heterogeneous catalyst in the oxidative coupling of methane at a temperature of 750° C. or less.
18. The catalyst of claim 14 , in combination with a support material.
19. A method for conversion of methane to C 2 + hydrocarbons, the method comprising contacting the catalyst of claim 14 with methane and an oxidant source.
20. The catalyst of claim 14 , further comprising a support, diluent, binder, or combinations thereof.
21. The catalyst of claim 14 , in the form of a pellet or extrudate.