Methane activation systems and related electrochemical apparatuses

Abstract

A method of forming a hydrocarbon product and hydrogen gas comprises introducing CH 4 to a positive electrode of an electrochemical cell comprising the positive electrode, a negative electrode, and a proton-conducting membrane between the positive electrode and the negative electrode. The proton-conducting membrane comprises an electrolyte material having an ionic conductivity greater than or equal to about 10 −2 S/cm at one or more temperatures within a range of from about 150° C. to about 600° C. A potential difference is applied between the positive electrode and the negative electrode of the electrochemical cell to produce the hydrocarbon product and the hydrogen gas. A CH 4 activation system and an electrochemical cell are also described.

1 . A methane (CH 4 ) activation system, comprising:
 a source of CH 4 ; and   an electrochemical apparatus in fluid communication with the source of CH 4 , and comprising:
 a housing structure configured and positioned to receive a CH 4  stream from the source of CH 4 ; and 
 an electrochemical cell within an internal chamber of the housing structure, and comprising:
 a positive electrode comprising a catalyst material formulated to accelerate reaction rates to produce CH 3   + , H + , and e −  through non-oxidative deprotonation of CH 4 , and to accelerate reaction rates to synthesize at least one hydrocarbon product from the produced CH 3   + ; 
 a negative electrode comprising another catalyst material formulated to accelerate reaction rates to produce H 2(g)  from the produced H +  and e − ; and 
 a proton-conducting membrane between the positive electrode and the negative electrode and comprising an electrolyte material having an ionic conductivity greater than or equal to about 10 −2  S/cm at one or more temperatures within a range of from about 150° C. to about 600° C. 
 
   
     
     
         2 . The CH 4  activation system of  claim 1 , wherein the electrolyte material of the proton-conducting membrane is selected from the group consisting of:
 a perovskite material having a H +  conductivity greater than about 10 −2  S/cm at one or more temperatures within a range of from about 400° C. to about 600° C.;   a solid acid material having a H +  conductivity greater than or equal to about 10 −2  S/cm at one or more temperatures within a range of from about 200° C. to about 400° C.; and   a polybenzimidazole (PBI) material having a H +  conductivity greater than or equal to about 10 −2  S/cm at one or more temperatures within a range of from about 150° C. to about 200° C.   
     
     
         3 . The CH 4  activation system of  claim 2 , wherein:
 the proton-conducting membrane comprises BZCYYb;   the catalyst material of the positive electrode comprises one or more of Fe@SiO 2  and Mo 2 C; and   the another catalyst material of the negative electrode comprises Ni—BZCYYb.   
     
     
         4 . The CH 4  activation system of  claim 2 , wherein:
 the proton-conducting membrane comprises CsH 2 PO 4 ;   the catalyst material of the positive electrode comprises one or more of Ni and a Ru—Co bimetallic compound; and   the another catalyst material of the negative electrode comprises Pt—CsH 2 PO 4 .   
     
     
         5 . The CH 4  activation system of  claim 2 , wherein:
 the proton-conducting membrane comprises H 3 PO 4 -doped PBI;   the catalyst material of the positive electrode comprises one or more of a Pd—Co bimetallic compound, a Pd—Pt bimetallic compound, and a Pd—Pt—Co trimetallic compound; and   the another catalyst material of the negative electrode comprises one or more of Ni and Pt.   
     
     
         6 . The CH 4  activation system of  claim 1 , further comprising a heating apparatus configured and positioned to heat one or more of the CH 4  stream and at least a portion of the electrochemical apparatus. 
     
     
         7 . The CH 4  activation system of  claim 1 , wherein the internal chamber comprises:
 a first region configured and positioned to receive the CH 4  stream and direct a hydrocarbon product stream from the electrochemical apparatus; and   a second region configured and positioned to receive the produced H 2(g) ,   the electrochemical cell separating the first region from the second region and the CH 4  substantially confined to the first region.   
     
     
         8 . The CH 4  activation system of  claim 1 , wherein the CH 4  stream comprises CH 4  and at least one C 2  to C 4  hydrocarbon compound. 
     
     
         9 . A methane (CH 4 ) activation system, comprising:
 a source of CH 4 ; and   an electrochemical apparatus in fluid communication with the source of CH 4 , and comprising:
 a housing structure configured and positioned to receive a CH 4  stream from the source of CH 4 ; and 
 an electrochemical cell within an internal chamber of the housing structure, and comprising:
 a positive electrode comprising a catalyst-doped material including particles comprising one or more of Ru, Rh, Ni, Ir, Mo, Zn, and Fe; 
 a negative electrode comprising a catalyst-doped perovksite material formulated to accelerate reaction rates to produce H 2(g)  from the produced H +  and e; and 
 
 a proton-conducting membrane between the positive electrode and the negative electrode and comprising an perovskite material having an ionic conductivity greater than or equal to about 10 −2  S/cm at one or more temperatures within a range of from about 150° C. to about 600° C. 
   
     
     
         10 . The CH 4  activation system of  claim 9 , wherein the catalyst-doped material of the positive electrode includes composite particles individually comprising:
 one or more of Ru, Rh, Ni, Ir, Mo, Zn, and Fe; and   one or more of silicon dioxide (SiO 2 ) and silicon carbide (SiC).   
     
     
         11 . The CH 4  activation system of  claim 10 , wherein the composite particles individually comprise one of:
 Fe and SiO 2  (Fe@SiO 2 );   Mo and SiO 2  (Mo@SiO 2 );   Fe and SiC (Fe@SiC); and   Mo and SiC (Mo@SiC).   
     
     
         12 . The CH 4  activation system of  claim 9 , wherein the catalyst-doped perovskite material of the negative electrode comprises Ni. 
     
     
         13 . The CH 4  activation system of  claim 9 , wherein the catalyst-doped material of the positive electrode includes one or more of elemental Ru particles, elemental Rh particles, elemental Ni particles, elemental Ir particles, elemental Mo particles, elemental Zn particles, and elemental Fe particles. 
     
     
         14 . The CH 4  activation system of  claim 9 , wherein the catalyst-doped material of the positive electrode includes a carbide of one or more of Ru, Rh, Ni, Ir, Mo, Zn, and Fe. 
     
     
         15 . An electrochemical apparatus, comprising:
 a positive electrode comprising a catalyst-doped material formulated to accelerate reaction rates to produce CH 3   + , H + , and e −  through non-oxidative deprotonation of CH 4 ;   a negative electrode comprising another catalyst-doped material formulated to accelerate reaction rates to produce H 2(g)  from the produced H +  and e − ; and   a proton-conducting membrane between the positive electrode and the negative electrode and comprising one or more of a perovskite material, a solid acid material, and a polybenzimidazole (PBI) material and exhibiting an ionic conductivity greater than or equal to about 10 −2  S/cm at one or more temperatures within a range of from about 150° C. to about 600° C.   
     
     
         16 . The electrochemical apparatus of  claim 15 , wherein the catalyst-doped material of the positive electrode is further formulated to accelerate at least one coupling reaction to synthesize at least one hydrocarbon product from the produced CH 3   + . 
     
     
         17 . The electrochemical apparatus of  claim 15 , wherein:
 the proton-conducting membrane comprises the solid acid material;   the catalyst-doped material of the positive electrode comprises one or more of Ni and a metallic material comprising Ru and Co; and   the another catalyst-doped material of the negative electrode comprises a cermet material comprising Pt and CsH 2 PO 4 .   
     
     
         18 . The electrochemical apparatus of  claim 15 , wherein:
 the proton-conducting membrane comprises the PBI material;   the catalyst-doped material of the positive electrode comprises a metallic material comprising two or more of Pd, Co, and Pt; and   the another catalyst-doped material of the negative electrode comprises one or more of Ni and Pt.   
     
     
         19 . The electrochemical apparatus of  claim 15 , wherein:
 the proton-conducting membrane comprises a perovskite material;   the catalyst-doped material of the positive electrode comprises one or more of Ru, Rh, Ni, Ir, Mo, Zn, and Fe; and   the another catalyst-doped material of the negative electrode comprises a cermet material comprising Ni.   
     
     
         20 . The electrochemical apparatus of  claim 15 , wherein the proton-conducting membrane is formulated to remain substantially adhered to the positive electrode and the negative electrode at current densities greater than or equal to about 0.1 A/cm 2 .