Heterogeneous catalysts

Abstract

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 C2+ hydrocarbons. Related methods for use and manufacture of the same are also disclosed.

1 . A method for conversion of methane to C2+ hydrocarbons, the method comprising contacting a catalyst with a gas comprising methane, the catalyst comprising:
 a base material comprising an oxide of two or more 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/Sr, Sr/K, Sr/Ga/Mg, Sr/Y, Sr/B/Y, Sr/Al, Sr/Ba/W, Sr/W/B and Sr/Ba/W/B,   provided that one of the lanthanide elements is not lanthanum when another lanthanide element is neodymium.   
     
     
         2 . The method of  claim 1 , wherein the methane is converted to C2+ hydrocarbons by an oxidative coupling of methane (OCM) reaction. 
     
     
         3 . The method of  claim 1 , wherein the gas further comprises an oxidant source. 
     
     
         4 . The method of  claim 3 , wherein the oxidant source is a gas enriched for oxygen. 
     
     
         5 . The method of  claim 3 , wherein the oxidant source is air. 
     
     
         6 . The method of  claim 1 , wherein the method is performed in the presence of ethane. 
     
     
         7 . The method of  claim 1 , wherein the oxide 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; 
 a and c are each independently numbers greater than 0; and 
 b, d, e, and f are independently 0 or a number greater than 0. 
   
     
     
         8 . The method of  claim 1 , wherein the catalyst comprises a C 2 + selectivity of greater than 50% and a methane conversion of greater than 20% when the catalyst is contacted with the gas at a temperature of 750° C. or less. 
     
     
         9 . The method of  claim 8 , wherein the catalyst further comprises a C2+ yield greater than 10% when the catalyst is contacted with the gas at a temperature of 750° C. or less. 
     
     
         10 . The method of  claim 9 , wherein the methane conversion, C 2+  selectivity, or C2+ yield, or combinations thereof, are measured in a 4 millimeter inner diameter tube with a methane to oxygen ratio of 5.5:1 using air as an oxidant, wherein the temperature is 650° C. 
     
     
         11 . A method for conversion of methane to C2+ hydrocarbons, the method comprising contacting a catalyst with a gas comprising methane, the catalyst comprising a Group 4 or lanthanide oxide in combination with an alkaline earth metal dopant selected from the group consisting of Ba/W, Ba/B, Ba/Sr, Ba/Ce, Ba/Hf, Y/Ba, Ca/B, Sr/Ba/W, Ba/W/B, Sr/Ba/B and Sr/Ba/W/B. 
     
     
         12 . The method of  claim 11 , wherein the methane is converted to C2+ hydrocarbons by an oxidative coupling of methane (OCM) reaction. 
     
     
         13 . The method of  claim 11 , wherein the gas further comprises an oxidant source. 
     
     
         14 . The method of  claim 13 , wherein the oxidant source is a gas enriched for oxygen. 
     
     
         15 . The method of  claim 13 , wherein the oxidant source is air. 
     
     
         16 . The method of  claim 11 , wherein the method is performed in the presence of ethane. 
     
     
         17 . The method of  claim 11 , wherein the dopant is Ba/W, Sr/Ba/W or Sr/Ba/W/B. 
     
     
         18 . The method of  claim 11 , wherein the catalyst comprises one of the following compositions: Ba/W/Nd 2 O 3  or Ba/W/Er 2 O 3 . 
     
     
         19 . The method of  claim 11 , wherein the catalyst comprises a C 2 + selectivity of greater than 50% and a methane conversion of greater than 20% when the catalyst is contacted with the gas at a temperature of 750° C. or less. 
     
     
         20 . The method of  claim 19 , wherein the catalyst further comprises a C2+ yield greater than 10% when the catalyst is contacted with the gas at a temperature of 750° C. or less. 
     
     
         21 . The method of  claim 20 , wherein the methane conversion, C 2+  selectivity, or C2+ yield, or combinations thereof, are measured in a 4 millimeter inner diameter tube with a methane to oxygen ratio of 5.5:1 using air as an oxidant, wherein the temperature is 650° C. 
     
     
         22 . A method for conversion of methane to C2+ hydrocarbons, the method comprising contacting a catalyst with a gas comprising methane, the catalyst comprising a mixed oxide base material and a dopant combination, the mixed oxide comprising erbium (Er) and at least one further lanthanide element, the 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. 
     
     
         23 . The method of  claim 22 , wherein the methane is converted to C2+ hydrocarbons by an oxidative coupling of methane (OCM) reaction. 
     
     
         24 . The method of  claim 22 , wherein the gas further comprises an oxidant source. 
     
     
         25 . The method of  claim 24 , wherein the oxidant source is a gas enriched for oxygen. 
     
     
         26 . The method of  claim 24 , wherein the oxidant source is air. 
     
     
         27 . The method of  claim 22 , wherein the method is performed in the presence of ethane. 
     
     
         28 . The method of  claim 22 , wherein the mixed oxide comprises a physical blend of Er, or an oxidized form thereof, and the further lanthanide element, or an oxidized form thereof. 
     
     
         29 . The method of  claim 28 , wherein the mixed oxide has the following formula (I):
   Ln x Er y O z   (I)
   wherein:
 Ln is the lanthanide element; 
 Er is erbium; 
 O is oxygen; and 
 x, y and z are each independently numbers greater than 0, wherein x, y and z are selected such that the overall charge of the catalyst is about 0. 
   
     
     
         30 . The method of  claim 29 , wherein x, y and z are selected such that z is from 150% to 200% of the sum of x and y. 
     
     
         31 . The method of  claim 29 , wherein the mixed oxide is LnErO 3  or Ln 3 ErO 6 . 
     
     
         32 . The method of  claim 22 , wherein the catalyst comprises a C2+ selectivity of greater than 50% and a methane conversion of greater than 20% when the catalyst is contacted with the gas at a temperature of 750° C. or less. 
     
     
         33 . The method of  claim 32 , wherein the catalyst further comprises a C2+ yield greater than 10% when the catalyst is contacted with the gas at a temperature of 750° C. or less. 
     
     
         34 . The method of  claim 33 , wherein the methane conversion, C 2+  selectivity, or C2+ yield, or combinations thereof, are measured in a 4 millimeter inner diameter tube with a methane to oxygen ratio of 5.5:1 using air as an oxidant, wherein the temperature is 650° C.