CATALYSTS FOR OXIDATIVE COUPLING OF METHANE
Catalysts, catalytic materials having catalysts present on supports and catalytic methods are provided. The catalysts, catalytic material and methods are useful in a variety of catalytic reactions, for example, the oxidative coupling of methane.
1 . A catalyst for oxidative coupling of methane having the following formula:
A x B y C z O 4 ,
wherein:
A is sodium (Na);
B is manganese (Mn), cerium (Ce) or a combination thereof;
C is tungsten (W);
O is oxygen; and
x, y and z are independently numbers greater than 0, and x, y and z are selected such that A x B y C z O 4 has an overall charge of 0,
the catalyst further comprising at least one dopant selected from the lanthanides,
wherein the catalyst comprises a C2+ selectivity of at least 20% when the catalyst is employed as a heterogeneous catalyst in oxidative coupling of methane (OCM) at a temperature of at least about 400° C. and a pressure of at least about 2 barg.
2 . The catalyst of claim 1 , wherein the catalyst comprises NaMnWO 4 .
3 . The catalyst of claim 1 , wherein the catalyst comprises NaCeWO 4 .
4 . The catalyst of claim 1 , wherein the catalyst comprises NaMn q Ce (1−q) WO 4 , wherein q is a number greater than 0 and less than 1.
5 . The catalyst of claim 1 , wherein the at least one dopant comprises La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tb, Yb or Lu.
6 . The catalyst of claim 1 , wherein the at least one dopant is an oxide of at least one lanthanide element.
7 . The catalyst of claim 6 , wherein the oxide of at least one lanthanide element comprises La 2 O 3 , Nd 2 O 3 , Er 2 O 3 or Pr 2 O 3 .
8 . The catalyst of claim 6 , wherein the oxide of at least one lanthanide element comprises Ln1 4−m Ln2 m O 6 , wherein Ln1 and Ln2 are each independently a lanthanide element, wherein Ln1 and Ln2 are not the same and m is a number ranging from greater than 0 to less than 4.
9 . The catalyst of claim 8 , wherein the oxide of at least one lanthanide element comprises La 3 NdO 6 , LaNd 3 O 6 , La 1.5 Nd 2.5 O 6 , La 2.5 Nd 1.5 O 6 , La 3.2 Nd 0.8 O 6 , La 3.5 Nd 0.05 O 6 , La 3.8 Nd 0.2 O 6 or combinations thereof.
10 . The catalyst of claim 1 , wherein the at least one dopant comprises nanowires.
11 . A catalyst comprising a perovskite having the following formula:
A 1 α A 2 β A 3 χ B 1 w B 2 x B 3 y B 4 z O 3 ,
wherein:
A 1 , A 2 and A 3 are each independently an element from group 2 of the periodic table;
B 1 , B 2 , B 3 and B 4 are each independently an element from group 4, group 13 or the lanthanides of the periodic table;
O is oxygen;
α, β, χ are each independently numbers ranging from 0 to 1, and α, β and χ are selected such that the sum of α, β, χ is about 1; and
w, x, y and z are each independently numbers ranging from 0 to 1, and w, x and y are selected such that the sum of w, x, y and z is about 1, and
wherein the catalyst comprises a C2+ selectivity of at least 20% when the catalyst is employed as a heterogeneous catalyst in oxidative coupling of methane (OCM) at a temperature of at least 400° C. and a pressure of at least about 2 barg.
12 .- 60 . (canceled)
61 . A catalyst comprising an oxide, a hydroxide or an oxyhydroxide of Samarium (Sm), wherein the catalyst comprises a C2+ selectivity of at least 20% when the catalyst is employed as a heterogeneous catalyst in oxidative coupling of methane (OCM) at a temperature of at least 400° C. and a pressure of at least about 2 barg.
62 .- 63 . (canceled)
64 . The catalyst of claim 1 , wherein the catalyst comprises a C2+ selectivity of at least 20% when the catalyst is employed as a heterogeneous catalyst in the OCM at a temperature of at least 600° C. and a pressure of at least about 8 barg.
65 . The catalyst of claim 1 , wherein the catalyst maintains at least 90% of the C2 selectivity after the catalyst is employed as a heterogeneous catalyst in the oxidative coupling of methane for about 1,000 hours.
66 . The catalyst of claim 1 , wherein the catalyst maintains at least 90% of the C2 selectivity after the catalyst is employed as a heterogeneous catalyst in the oxidative coupling of methane for about 1,000 hours at gas hourly space velocity (GHSV).
67 . The catalyst of claim 1 , in combination with a support.
68 . The catalyst of claim 67 , wherein the catalyst is disposed on, impregnated in or a combination thereof, the support.
69 . The catalyst of claim 68 , wherein the catalysts is disposed on the support as a film.
70 . The catalyst of claim 68 , wherein the catalysts is disposed on the support as particles.
71 . (canceled)
72 . The catalyst of claim 67 , wherein the support comprises alpha phase alumina, gamma phase alumina or a combination thereof.
73 . The catalyst of claim 72 , wherein the alumina is at least 75% alpha phase alumina.
74 .- 75 . (canceled)
76 . The catalyst of claim 67 , wherein the support comprises zirconia.
77 . The catalyst of claim 76 , wherein the support further comprises a stabilizing agent selected from Yb, Ce, Al or combinations thereof.
78 . The catalyst of claim 67 , wherein the support comprises a surface area of at least 0.5 m 2 /g.
79 . A catalytic material comprising an OCM active catalyst in combination with a support, wherein the OCM active catalyst comprises one or more elements from the lanthanides, and the support comprises alpha phase alumina, gamma phase alumina or a combination thereof.
80 .- 88 . (canceled)
89 . A formed catalytic material comprising the catalyst of claim 1 , the formed catalytic material further comprising a crushing strength greater than 1 N/mm 2 after exposing to steam for certain time.
90 .- 92 . (canceled)
93 . A method for oxidative coupling of methane (OCM), the method comprising contacting a feed gas comprising methane and oxygen with a catalyst of claim 1 , at a temperature ranging from about 400° C. to about 950° C. to form a product gas comprising C2+ hydrocarbons.
94 .- 105 . (canceled)