Alkali metal doped molybdenum carbide supported on gamma-alumina for selective co2 hydrogenation into co

Abstract

A class of catalysts for CO 2 hydrogenation via the reverse water-gas shift (RWGS) reaction to selectively produce CO for down-stream hydrocarbon synthesis. Alkali metal-doped molybdenum carbide, supported on gamma alumina (A-Mo 2 C/γ-Al 2 O 3 , A=K, Na, Li), is synthesized by co-impregnation of molybdenum and alkali metal precursors onto a γ-Al 2 O 3 support. The A-Mo/γ-Al 2 O 3 catalyst is then carburized to form the A-Mo 2 C/γ-Al 2 O 3 . Also disclosed is the related method for CO 2 hydrogenation via the RWGS reaction using the A-Mo 2 C/γ-Al 2 O 3 catalyst.

What is claimed as new and desired to be protected by Letters Patent of the United States is: 
     
         1 . A supported heterogeneous catalyst material for catalyzing the reverse water-gas shift (RWGS) reaction for the selective formation of CO, comprising:
 a support material comprising γ-Al 2 O 3 ; and   an active material comprising alkali-metal doped molybdenum carbide.   
     
     
         2 . The catalyst material of  claim 1 , wherein the alkali-metal component of the active material comprises one or more alkali-metal precursors in elemental form or in the form of oxides, said metals being selected from the group consisting of K, Na, Li, or any combination thereof. 
     
     
         3 . The catalyst material of  claim 1 , wherein the molybdenum component of the active material comprises one or more molybdenum precursors in the form of carbides, oxycarbides, oxides, elemental molybdenum, or any combination thereof. 
     
     
         4 . A method for making a catalyst for use in carbon dioxide hydrogenation via the reverse water-gas shift (RWGS) reaction for the selective formation of CO, comprising:
 co-impregnating molybdenum and alkali-metal precursors onto a γ-Al 2 O 3  support, wherein the alkali metal is K, Na, or Li;   drying and calcining impregnated γ-Al 2 O 3  support; and   carburizing the dried and calcined γ-Al 2 O 3  support to form A-Mo 2 C/γ-Al 2 O 3 , where A is K, Na, or Li.   
     
     
         5 . The method of  claim 4 , wherein the loading of Mo is in the range of 1 to 70%. 
     
     
         6 . The method of  claim 4 , wherein the loading of the alkali metal is in the range of 0.1 to 15%. 
     
     
         7 . The method of  claim 4 , wherein the carburization is performed at a temperature in the range of 400 to 1000° C. 
     
     
         8 . A method for CO 2  hydrogenation via the reverse water-gas shift (RWGS) reaction for the selective formation of CO, comprising:
 co-impregnating molybdenum and alkali-metal precursors onto a γ-Al 2 O 3  support, wherein the alkali metal is K, Na, or Li;   drying and calcining impregnated γ-Al 2 O 3  support;   carburizing the dried and calcined γ-Al 2 O 3  support to form A-Mo 2 C/γ-Al 2 O 3 , wherein A is K, Na, or Li; and   reacting the A-Mo 2 C/γ-Al 2 O 3  with CO 2  and H 2  to form CO.   
     
     
         9 . The method of  claim 8 , wherein the loading of Mo is in the range of 1 to 70%. 
     
     
         10 . The method of  claim 8 , wherein the loading of the alkali metal is in the range of 0.1 to 15%. 
     
     
         11 . The method of  claim 8 , wherein the carburization is performed at a temperature in the range of 400 to 1000° C. 
     
     
         12 . The method of  claim 8 , wherein the reaction is performed while applying external heat. 
     
     
         13 . The method of  claim 8 , wherein the reaction is performed at a temperature in the range of 250 to 1000° C. 
     
     
         14 . The method of  claim 8 , wherein the reaction is performed at a pressure between 0 and 350 psig. 
     
     
         15 . The method of  claim 8 , wherein the reaction is performed while flowing carbon dioxide, hydrogen gas, or any combination thereof, over the A-Mo 2 C/γ-Al 2 O 3  catalyst material. 
     
     
         16 . The method of  claim 8 , wherein the reaction is performed while applying external heat and flowing carbon dioxide, hydrogen gas, or any combination thereof, over the A-Mo 2 C/γ-Al 2 O 3  catalyst material. 
     
     
         17 . The method of  claim 8 , wherein the CO 2  hydrogenation via the RWGS reaction achieves a CO yield of 12% or greater. 
     
     
         18 . The method of  claim 8 , wherein the CO 2  hydrogenation via the RWGS reaction achieves a CO selectivity of 90% or greater.