CATALYSTS AND METHODS FOR NATURAL GAS PROCESSES
Catalysts and catalytic methods are provided. The catalysts and methods are useful in a variety of catalytic reactions, for example, the oxidative coupling of methane.
1 . A catalyst comprising the following formula (IA):
A x B y C v D w O z (IA)
wherein:
A is a lanthanide or group 4 element;
B is a group 2 element;
C is a group 13 element;
D is a lanthanide element;
O is oxygen;
v and w are independently numbers greater than 0;
x, y and z are independently numbers greater than 0, and v, w, x, y and z are selected such that A x B y C v D w O z has an overall charge of 0.
2 . The catalyst of claim 1 , wherein A is a lanthanide.
3 . The catalyst of claim 2 , wherein A is lanthanum, cerium, praseodymium or neodymium.
4 . The catalyst of claim 1 , wherein A is a Group 4 element.
5 . The catalyst of claim 4 , wherein A is titanium, zirconium or hafnium.
6 . The catalyst of claim 1 , wherein B is magnesium, calcium, strontium or barium.
7 . The catalyst of claim 1 , wherein A is lanthanum and B is strontium, A is cerium and B is barium, A is praseodymium and B is barium, A is cerium and B is strontium, A is titanium and B is barium, A is titanium and B is strontium or A is titanium and B is calcium.
8 . The catalyst of claim 1 , wherein C is aluminum, gallium, indium or thallium.
9 . The catalyst of claim 1 , wherein D is lanthanum, neodymium, gadolinium or ytterbium.
10 . The catalyst of claim 1 , wherein:
A is titanium, zirconium or cerium;
B is calcium, strontium or barium;
C is aluminum, gallium or indium; and
D is lanthanum, neodymium; gadolinium or ytterbium.
11 . The catalyst of claim 1 , comprising one of the following formulas: Ce x Ba y In v Nd w O 3 ; Ti x Ca y In v La w O 3 ; Ti x Ca y In v Nd w O 3 ; Ti x Ca y In v Gd w O 3 ; Ti x Ca y In v Yb w O 3 ; Zr x Ca y In v La w O 3 ; Zr x Ca y In v Nd w O 3 ; Zr x Ca y In v Gd w O 3 ; Zr x Ca y In v Yb w O 3 ; Ce x Ca y In v La w O 3 ; Zr x Ca y In v Nd w O 3 ; Zr x Ca y In v Gd w O 3 ; Zr x Ca y In v Yb w O 3 ; Ti x Sr y In v La w O 3 ; Ti x Sr y In v Nd w O 3 ; Ti x Sr y In v Gd w O 3 ; Ti x Sr y In v Yb w O 3 ; Zr x Sr y In v La w O 3 ; Zr x Sr y In v Nd w O 3 ; Zr x Sr y In v Gd w O 3 ; Zr x Sr y In v Yb w O 3 ; Ce x Sr y In v La w O 3 ; Ce x Sr y In v Nd w O 3 ; Ce x Sr y In v Gd w O 3 ; Ce x Sr y In v Yb w O 3 ; Ti x Ba y In v La w O 3 ; Ti x Ba y In v Nd w O 3 ; Ti x Ba y In v Gd w O 3 ; Ti x Ba y In v Yb w O 3 ; Zr x Ba y In v La w O 3 ; Zr x Ba y In v Nd w O 3 ; Zr x Ba y In v Gd w O 3 ; Zr x Ba y In v Yb w O 3 ; Ce x Ba y In v La w O 3 ; Ce x Ba y In v Nd w O 3 ; Ce x Ba y In v Gd w O 3 or Ce x Ba y In v Yb w O 3 .
12 . The catalyst of claim 1 , wherein z is 3.
13 . The catalyst of claim 1 , wherein the sum of v, w, x and y is 2.
14 . The catalyst of claim 1 , wherein v and w each independently range from about 0.1 to about 0.6.
15 . The catalyst of claim 1 , wherein x ranges from about 0.2 to about 0.8.
16 . The catalyst of claim 1 , wherein y ranges from about 0.4 to about 1.0.
17 . The catalyst of claim 1 , wherein v ranges from about 0.25 to about 0.45, w ranges from about 0.4 to about 0.6, x ranges from about 0.3 to about 0.5 and y ranges from about 0.6 to about 1.0.
18 . The catalyst of claim 1 , wherein the catalyst is a nanostructured catalyst.
19 . The catalyst of claim 18 , wherein the catalyst is a nanowire.
20 . The catalyst of claim 1 , wherein the catalyst is a bulk catalyst.
21 . The catalyst of claim 1 , in combination with a diluent or support.
22 . A formed catalytic material comprising the catalyst of claim 1 .
23 . The formed catalytic material of claim 22 , wherein the formed catalytic material is an extrudate or a tableted catalytic material.
24 . (canceled)
25 . The catalyst of claim 1 , wherein a C2+ selectivity of the catalyst in an oxidative couple of methane (OCM) reaction is greater than about 50% when the OCM reaction is conducted at temperatures of about 700° C. or lower.
26 . The catalyst of claim 1 , wherein the catalyst has a catalytic activity to achieve a methane conversion of greater than 10% and a C2+ selectivity of greater than 50% in an oxidative coupling of methane (OCM) reaction when the catalyst contacted with methane at temperatures of about 700° C. or lower.
27 . A method for the oxidative coupling of methane, the method comprising contacting methane with the catalyst of claim 1 , thereby converting the methane to C2 hydrocarbons, C2+ hydrocarbons, or combinations thereof.
28 . (canceled)
29 . A method for performing the oxidative coupling of methane, the method comprising flowing a gas comprising methane from a front end to a back end of a catalyst bed comprising an OCM active catalyst, the catalyst bed having a total length L and a total OCM active catalyst surface area, wherein greater than 50% of the total OCM active catalyst surface area resides in a portion of the catalyst bed ranging from the front end to a distance equal to 50% of L.
30 - 37 . (canceled)
38 . A catalyst bed comprising a front end, a back end and an OCM active catalyst, the catalyst bed having a total length L and a total OCM active catalyst surface area, wherein greater than 50% of the total OCM active surface area resides in a portion of the catalyst bed ranging from the front end to a distance equal to 50% of L.
39 . A formed catalytic material comprising first and second OCM active catalysts, wherein the first OCM active catalyst is a nanostructured catalyst having a BET surface area of greater than 5 m 2 /g, and the second OCM active catalyst is a catalyst having a BET surface area of less than 2 m 2 /g, and wherein the catalytic material has a volume loss of less than 20% when heated to 900° C. in air for 100 hours.
40 - 50 . (canceled)
51 . A method for preparing a formed catalytic material, the method comprising:
i) providing a first nanostructured OCM active catalyst having a BET surface area of greater than 5 m 2 /g;
ii) sintering the first nanostructured OCM active catalyst at a temperature above 1000° C. to obtain a second OCM active catalyst having a BET surface area of less than 2 m 2 /g;
iii) admixing the first and second OCM active catalysts; and
iv) forming the mixture to obtain the formed catalytic material.
52 - 64 . (canceled)