Layered reactive elements in a thermo-electrochemical reactor for hydrogen and carbon monoxide production and method for using the same

Abstract

A method and reactor for a hybrid thermo-electrochemical cycle using a layered reactive element is disclosed. The method includes heating the reactive element with a heat source, the reactive element having a metal oxide core that is redox-active, an outer layer, and an ion conductor layer between the core and the outer layer. The method includes increasing a chemical potential of oxygen in the core, driving O2− ions out as O2, the chemical potential increased through applying a first bias voltage between the core and the outer layer. The method includes exposing the reactive element to an input gas, and decreasing the chemical potential of oxygen in the core, driving oxygen from the input gas into the core leaving a gas product, the chemical potential decreased through applying a second bias voltage between the core and the outer layer. The first and second bias voltages have opposite polarity.

What is claimed is: 
     
         1 . A thermo-electrochemical reactor, comprising:
 at least one layered reactive element, each layered reactive element comprising:
 a metal oxide core that is redox-active and is a mixed ionic-electronic conductor (MIEC), 
 an outer layer that is also an MIEC, 
 an ion conductor layer between the metal oxide core and the outer layer, 
 a TEC reduction mode, and 
 a TEC oxidation mode; 
   a controller communicatively coupled to the metal oxide core and the outer layer of each of the at least one layered reactive element;   a heat source;   wherein, for each layered reactive element, the TEC reduction mode comprises the metal oxide core having an increased chemical potential of oxygen relative to a gas phase that drives O 2−  ions out of the metal oxide core, through the ion conductor layer and the outer layer and into the gas phase as O 2 , with the chemical potential of oxygen in the metal oxide core being increased relative to the gas phase through applying a first bias voltage between the metal oxide core and the outer layer;   wherein, for each layered reactive element, the TEC oxidation mode comprises the metal oxide core having a decreased chemical potential of oxygen relative to the gas phase that drives one of oxygen from steam and oxygen from carbon dioxide back into the metal oxide core, through the ion conductor layer and the outer layer, leaving a gas product that is one of H 2  in the gas phase and CO in the gas phase, with the chemical potential of oxygen in the metal oxide core being decreased relative to the gas phase through applying a second bias voltage between the metal oxide core and the outer layer;   wherein the controller is configured to drive the thermo-electrochemical reactor to carry out a TEC cycle by alternating between applying the first bias voltage and applying the second bias voltage to at least one layered reactive element while the at least one layered reactive element is being heated by the heat source, cycling the at least one layered reactive element between the TEC reduction mode and the TEC oxidation mode;   wherein the first bias voltage and the second bias voltage have opposite polarity.   
     
     
         2 . The thermo-electrochemical reactor of  claim 1 , wherein the at least one layered reactive element is hollow. 
     
     
         3 . The thermo-electrochemical reactor of  claim 1 , wherein each layered reactive element of the at least one layered reactive element comprises two metal oxide cores, two ion conductor layers, and two outer layers. 
     
     
         4 . The thermo-electrochemical reactor of  claim 1 , wherein the layered reactive element is substantially planar. 
     
     
         5 . The thermo-electrochemical reactor of  claim 1 , wherein the metal oxide core comprises a perovskite. 
     
     
         6 . The thermo-electrochemical reactor of  claim 5 , wherein the metal oxide core comprises CAM28. 
     
     
         7 . The thermo-electrochemical reactor of  claim 1 , wherein the outer layer is gadolinium-doped ceria (GDC). 
     
     
         8 . The thermo-electrochemical reactor of  claim 1 , wherein the ion conductor layer is yttria-stabilized zirconia. 
     
     
         9 . The thermo-electrochemical reactor of  claim 1 :
 wherein the thermo-electrochemical reactor comprises a plurality of layered reactive elements;   wherein at least one layered reactive element of the plurality of layered reactive elements is in the TEC oxidation mode while at least a different layered reactive element of the plurality of layered reactive elements is in the TEC reduction mode; and   wherein the plurality of layered reactive elements move throughout the thermo-electrochemical reactor as the controller drives the thermo-electrochemical reactor to carry out the TEC cycle.   
     
     
         10 . The thermo-electrochemical reactor of  claim 1 :
 wherein the thermo-electrochemical reactor further comprises an insulated housing, a gas inlet, and a gas outlet;   wherein the at least one layered reactive element remains motionless with respect to the insulated housing as the controller cycles the at least one layered reactive element between the TEC oxidation mode and the TEC reduction mode.   
     
     
         11 . The thermo-electrochemical reactor of  claim 1 , wherein the heat source is solar-based. 
     
     
         12 . The thermo-electrochemical reactor of  claim 1 , wherein the controller is further configured displace the gas product with a sweep gas, the displaced gas product extracted through a gas outlet. 
     
     
         13 . The thermo-electrochemical reactor of  claim 12 , wherein the sweep gas is steam. 
     
     
         14 . A method for carrying out a hybrid thermo-electrochemical cycle using a layered reactive element, comprising:
 heating the layered reactive element with a heat source, the layered reactive element comprising a metal oxide core that is redox-active and is a mixed ionic-electronic conductor (MIEC), an outer layer that is also an MIEC, and an ion conductor layer between the metal oxide core and the outer layer;   increasing a chemical potential of oxygen in the metal oxide core, relative to a gas phase, thereby driving O 2−  ions out of the metal oxide core, through the ion conductor layer and the outer layer and into the gas phase as O 2 , the chemical potential of oxygen in the metal oxide core being increased relative to the gas phase through applying a first bias voltage between the metal oxide core and the outer layer;   exposing the layered reactive element to an input gas, the input gas displacing the O 2  in the gas phase;   decreasing the chemical potential of oxygen in the metal oxide core, relative to the gas phase, thereby driving oxygen from the input gas into the metal oxide core, through the ion conductor layer and the outer layer, leaving a gas product in the gas phase, with the chemical potential of oxygen in the metal oxide core being decreased relative to the gas phase through applying a second bias voltage between the metal oxide core and the outer layer; and   extracting the gas product by displacing the gas product with a sweep gas;   wherein the first bias voltage and the second bias voltage have opposite polarity.   
     
     
         15 . The method of  claim 14 , wherein the sweep gas is steam. 
     
     
         16 . The method of  claim 14 , wherein the input gas is one of steam and carbon dioxide, and wherein the gas product is one of H 2  and CO. 
     
     
         17 . The method of  claim 14 , wherein the metal oxide core comprises a perovskite. 
     
     
         18 . The method of  claim 14 , wherein the metal oxide core comprises CAM28. 
     
     
         19 . The method of  claim 14 , wherein the outer layer is gadolinium-doped ceria (GDC). 
     
     
         20 . The method of  claim 14 , wherein the ion conductor layer is yttria-stabilized zirconia.