A microchanneled solid electrolyte and related electrolyzer for enhanced electrochemical reduction of co2

Abstract

The present techniques relate to a microchanneled solid electrolyte (MSE), an electrolyzer and a method including or using the MSE for in-situ regeneration and collection of CO 2 during a CO 2 electroreduction operation. The MSE includes an anion conducting layer configured to conduct (bi) carbonate anions from a surface of an adjacent cathode; a cation conducting layer configured to conduct protons from a surface of an adjacent anode; and an integrated channel layer comprising multiple microchannels formed between the anion conducting layer and the cation conducting layer. The microchannels define a hollow path extending across the integrated channel layer for receiving the (bi) carbonate anions from the anion conducting layer and the protons from the cation conducting layer, thereby locally regenerating and collecting CO 2 along and within the microchannels.

1 . A microchanneled solid electrolyte (MSE) for in-situ regeneration and collection of carbon dioxide (CO 2 ) during a CO 2  electroreduction operation, the MSE comprising:
 an anion conducting layer configured to conduct (bi) carbonate anions from a surface of an adjacent cathode;   a cation conducting layer configured to conduct protons from a surface of an adjacent anode; and   an integrated channel layer comprising multiple microchannels formed between the anion conducting layer and the cation conducting layer;   wherein the microchannels define a hollow path extending across the integrated channel layer for receiving the (bi) carbonate anions from the anion conducting layer and the protons from the cation conducting layer, thereby locally regenerating and collecting CO 2  along and within the microchannels.   
     
     
         2 . The MSE of  claim 1 , wherein the microchannels are defined on a surface of the cation conducting layer to produce the integrated channel layer forming a one-piece structure with the cation conducting layer. 
     
     
         3 . The MSE of  claim 1 , wherein the microchannels are defined on a surface of the anion conducting layer to produce the integrated channel layer forming a one-piece structure with the anion conducting layer. 
     
     
         4 . The MSE of  claim 1 , wherein the integrated channel layer is a separate microporous structure positioned between the anion conducting layer and the cation conducting layer. 
     
     
         5 . The MSE of any one of  claims 1 to 4 , wherein the microchannels are in fluid communication with one another to define a network that directs the regenerated CO 2  from a central region of the integrated channel layer to an edge region of the integrated channel layer. 
     
     
         6 . The MSE of  claim 5 , wherein the network of microchannels defines an interconnected diamond pattern. 
     
     
         7 . The MSE of  claim 5 , wherein the network of microchannels defines an interconnected square pattern. 
     
     
         8 . The MSE of  claim 5 , wherein the network of microchannels defines an interconnected circular pattern. 
     
     
         9 . The MSE of any one of  claims 1 to 8 , wherein the microchannels are sized and shaped to maintain a maximum pressure below 100 kPa, 90 kPa, 80 kPa, 70 kPa, 60 kPa, 50 kPa, 40 kPa, 30 kPa, 20 kPa or 10 kPa. 
     
     
         10 . The MSE of any one of  claims 1 to 9 , wherein the microchannels are sized and shaped to maintain a voltage drop below 500 mV, 400 mV, 300 mV, 200 mV, or 100 mV. 
     
     
         11 . The MSE of any one of  claims 1 to 10 , wherein the microchannels have a channel depth of at most 125 μm, between 10 and 100 μm or between 20 and 80 μm. 
     
     
         12 . The MSE of any one of  claims 1 to 11 , wherein the microchannels have a pore path width between 25 and 150 μm or between 25 and 75 μm. 
     
     
         13 . The MSE of any one of  claims 1 to 12 , wherein the integrated channel layer has a porosity between 5% and 95%, between 10% and 80%, between 15% and 70%, between 20% and 60% or between 25% and 50%. 
     
     
         14 . The MSE of any one of  claims 1 to 13 , wherein the microchannels are uniform across the integrated channel layer. 
     
     
         15 . The MSE of any one of  claims 1 to 14 , wherein the microchannels have a non-circular cross-section including cross-sections of elliptical, circular, rectangular, or square shape. 
     
     
         16 . The MSE of any one of  claims 1 to 15 , wherein the anion conducting layer comprises fixed cations derived from piperidinium, imidazolium, or benzimidazolium. 
     
     
         17 . A system for electroreduction of CO 2  into carbon products, the system comprising:
 an electrolyzer comprising:
 a cathode flow field having an inlet to receive a CO 2  gas stream; 
 a cathode in fluid communication with the cathode flow field to operate electroreduction of the CO 2  gas stream; 
 an anode flow field having an inlet to receive an anolyte stream; 
 an anode in fluid communication with the anode flow field; and 
 a microchanneled solid electrolyte (MSE) positioned between the cathode and the anode in a forward-biased configuration, the MSE as defined in any one of claims  1  to  16  and releasing a concentrated CO 2  stream comprising CO 2  and water to the cathode flow field when the CO 2  gas stream is electroreduced; and 
   a recycle loop in fluid communication with the cathode flow field for recovering the concentrated CO 2  stream from an outlet of the cathode flow field and redirect the regenerated and collected CO 2  from the concentrated CO 2  stream back to the cathode flow field for serving as at least a part of the CO 2  gas stream.   
     
     
         18 . The electrolyzer of  claim 17 , wherein the recycle loop comprises:
 a first tubing for recovering the concentrated CO 2  stream comprising water and regenerated CO 2  from the microchannels;   a liquid-gas separator in fluid communication with the first tubing to receive the concentrated CO 2  stream and separate the concentrated CO 2  stream into a regenerated CO 2  gas stream and a water stream; and   a second tubing interconnected the liquid-gas separator to the cathode flow field for recycling the regenerated CO 2  gas stream to the cathode flow field.   
     
     
         19 . The system of  claim 18 , wherein the second tubing is in fluid communication with the inlet of the cathode flow field to provide the regenerated CO 2  gas stream along with the CO 2  gas stream to the cathode flow field. 
     
     
         20 . The system of any one of  claims 17 to 19 , where the concentrated CO 2  stream comprises at least 80%, 85%, 90% or 95% of CO 2 , and an anode tail gas recovered from the anode flow field comprises at most 1%, 2%, 3%, 4% or 5% of CO 2 . 
     
     
         21 . The system of any one of  claims 17 to 20 , wherein the anolyte is free of mobile alkali metal cations. 
     
     
         22 . The system of any one of  claims 15 to 20 , wherein the anolyte is water or a solution of H 2 SO 4 , HClO 4 , or a combination thereof. 
     
     
         23 . The system of any one of  claims 17 to 22 , wherein the CO 2  gas stream is supplied at a CO 2  feed rate between 0.25 sccm·cm −2  and 2 sccm·cm −2 , 0.5 sccm·cm −2  and 1.5 sccm·cm −2 , or 0.8 sccm·cm −2  and 1 sccm·cm −2 . 
     
     
         24 . The system of any one of  claims 17 to 23 , wherein the electrolyzer is operated at a current density between 40 mA·cm −2  and 240 mA·cm −2 , 50 mA·cm −2  and 200 mA·cm −2 , 60 mA·cm −2  and 160 mA·cm −2 , 80 mA·cm −2  and 120 mA·cm −2 , or 90 mA·cm −2  and 100 mA·cm −2 . 
     
     
         25 . A method for reducing CO 2  losses during electroreduction of CO 2  in a CO 2 RR electrolyzer comprising a cathodic compartment and an anodic compartment, the method comprising:
 supplying a CO 2  gas stream to the cathodic compartment operating CO 2  reduction reactions producing (bi) carbonate and hydroxide anions;   supplying an anolyte stream to the anodic compartment operating anodic reactions producing protons;   allowing generation and collecting of a concentrated CO 2  stream in microchannels positioned between the cathodic compartment and the anodic compartment by:
 directing (bi) carbonate and hydroxide anions from the cathode to the microchannels via an anion conducting layer, and 
 directing protons from the anode to the microchannels via a cation conducting layer; 
   recovering the concentrated CO 2  stream from the CO 2 RR electrolyzer;   separating water and a regenerated CO 2  gas stream from the concentrated CO 2  stream; and   recycling at least a portion of the regenerated CO 2  gas stream to the cathodic compartment of the CO 2 RR electrolyzer.   
     
     
         26 . The method of  claim 25 , wherein supplying the CO 2  gas stream is performed at a CO 2  feed rate between 0.25 sccm·cm −2  and 2 sccm·cm −2 , 0.5 sccm·cm −2  and 1.5 sccm·cm −2 , or 0.8 sccm·cm −2  and 1 sccm·cm −2 . 
     
     
         27 . The method of  claim 25 or 26 , comprising operating the CO 2 RR electrolyzer at a current density between 40 mA·cm −2  and 240 mA·cm −2 , 50 mA·cm −2  and 200 mA·cm −2 , 60 mA·cm −2  and 160 mA·cm −2 , 80 mA·cm −2  and 120 mA·cm −2 , or 90 mA·cm −2  and 100 mA·cm −2 . 
     
     
         28 . The method of any one of  claims 25 to 27 , comprising controlling at least one of:
 a maximum pressure within the microchannels below 100 kPa, 90 kPa, 80 kPa, 70 kPa, 60 kPa, 50 kPa, 40 kPa, 30 kPa, 20 kPa or 10 kPa; and   a voltage drop below 500 mV, 400 mV, 300 mV, 200 mV, or 100 mV.   
     
     
         29 . The method of any one of  claims 25 to 28 , comprising providing the microchannels with at least one of:
 a channel depth of at most 125 μm, between 10 and 100 μm or between 20 and 80 μm; and   a pore path width between 25 and 125 μm or between 25 and 75 μm.   
     
     
         30 . The method of any one of  claims 25 to 29 , comprising providing the microchannels in an integrated channel layer between the anion conducting layer and the cation conduction layer, the integrated channel layer having a porosity between 5% and 95%, between 10% and 80%, between 15% and 70%, between 20% and 60% or between 25% and 50%. 
     
     
         31 . The method of any one of  claims 25 to 30 , comprising providing the anion conducting layer with fixed cations derived from piperidinium, imidazolium, or benzimidazolium.