System and High Surface Area Electrodes for the Electrochemical Reduction of Carbon Dioxide
Methods and systems for electrochemical conversion of carbon dioxide to organic products including formate and formic acid are provided. A system may include an electrochemical cell including a cathode compartment containing a high surface area cathode and a bicarbonate-based catholyte saturated with carbon dioxide. The high surface area cathode may include an indium coating and having a void volume of between about 30% to 98. The system may also include an anode compartment containing an anode and an acidic anolyte. The electrochemical cell may be configured to produce a product stream upon application of an electrical potential between the anode and the cathode.
1 . A system for electrochemical reduction of carbon dioxide into products, comprising:
a first electrochemical cell including:
a cathode compartment containing a high surface area cathode and a bicarbonate-based catholyte saturated with carbon dioxide, the high surface area cathode including an indium coating and having a void volume of between about 30% to 98%; and
an anode compartment containing an anode and an acidic anolyte,
wherein the electrochemical cell is configured to produce a product upon application of an electrical potential between the anode and the cathode.
2 . The system of claim 1 further comprising:
a cation ion exchange membrane positioned between the cathode compartment and the anode compartment.
3 . The system of claim 1 , wherein the high surface area cathode includes indium deposited on tin.
4 . The system of claim 3 , wherein the high surface area cathode further includes at least one of a copper substrate or a conductive substrate, the tin layered on the at least one of the copper substrate or the conductive substrate.
5 . The system of claim 1 , wherein the anode comprises an electrocatalytic coating including at least one of ruthenium oxide, iridium oxide, platinum, a platinum oxide, gold, or a gold oxide.
6 . The system of claim 1 , wherein the product of the first electrochemical cell includes an alkali metal formate.
7 . The system of claim 1 , wherein the cathode compartment further contains a homogenous heterocyclic amine catalyst.
8 . The system of claim 7 , wherein the homogenous heterocyclic amine catalyst is selected from the group consisting of 4-hydroxy pyridine, adenine, a heterocyclic amine containing sulfur, a heterocyclic amine containing oxygen, an azole, a benzimidazole, a bipyridine, a furan, an imidazole, an imidazole related species with at least one five-member ring, an indole, a lutidine, a methylimidazole, an oxazole, a phenanthroline, a pterin, a pteridine, pyridine, a pyridine related species with at least one six-member ring, a pyrrole, a quinoline, or a thiazole, and mixtures thereof.
9 . The system of claim 1 , further comprising:
a first separator configured to receive an output from the anode compartment, wherein at least a portion of a product of the first separator is recycled to the anode compartment; and
a second separator configured to receive an output from the cathode compartment, wherein at least a portion of a product of the second separator is recycled to the cathode compartment.
10 . The system of claim 1 , further comprising:
a second electrochemical cell including:
a catholyte compartment comprising a cathode;
an anolyte compartment comprising an anode; and
an ion exchange compartment positioned between the catholyte compartment and the anolyte compartment, the ion exchange compartment including an input port configured to receive the product from the electrochemical cell,
wherein the second electrochemical cell is configured to produce a second product upon application of an electrical potential between the anode and the cathode.
11 . The system of claim 10 , wherein the second product of the second electrochemical cell includes formic acid.
12 . The system of claim 10 , wherein the bicarbonate-based catholyte of the first electrochemical cell includes potassium bicarbonate, wherein the product of the first electrochemical cell includes potassium formate, and wherein the second product of the second electrochemical cell includes formic acid.
13 . The system of claim 10 , further comprising:
a third separator configured to receive an output from the anolyte compartment of the second electrochemical cell, wherein at least a portion of a product of the third separator is recycled to the anolyte compartment of the second electrochemical cell; and
a fourth separator configured to receive an output from the catholyte compartment of the second electrochemical cell, wherein at least a portion of a product of the fourth separator is recycled to the catholyte compartment of the second electrochemical cell.
14 . The system of claim 13 , further comprising:
a catholyte recycle reactor, the catholyte recycle reactor including an input port configured to receive at least a portion of the product from the fourth separator, wherein at least a portion of a product of the catholyte recycle reactor is recycled to the cathode compartment of the first electrochemical cell.
15 . The system of claim 14 , further comprising:
a carbon dioxide distribution module, the carbon dioxide distribution module configured to receive carbon dioxide from at least a portion of the product of one or more of the first separator, the second separator, the third separator, and the fourth separator, wherein the carbon dioxide distribution module is configured to distribute carbon dioxide to one or more of the cathode compartment of the first electrochemical cell and the catholyte recycle reactor.
16 . The system of claim 10 , wherein the second electrochemical cell includes a plurality of bipolar membranes.
17 . The system of claim 10 , further comprising:
a nano-filtration system coupled between the electrochemical cell and the second electrochemical cell, the nano-filtration system configured to receive the product from the first electrochemical cell and to separate at least one of a carbonate or a bicarbonate from an alkali metal formate, the nano-filtration system configured to send the alkali metal formate to the ion exchange compartment of the second electrochemical cell.
18 . A system for electrochemical reduction of carbon dioxide into products, comprising:
an electrolyzer system configured for the reduction of carbon dioxide to an alkali metal formate, the electrolyzer system including:
an electrolyzer, comprising:
a first compartment containing an anolyte and an anode;
a second compartment containing a catholyte and a high surface area cathode, the catholyte including an alkali metal bicarbonate solution saturated with carbon dioxide, the high surface area cathode including an indium coating on tin and having a void volume of between about 30% to 98%, the high surface area cathode configured to reduce the carbon dioxide to the alkali metal formate;
a cation exchange membrane positioned between the first compartment and the second compartment;
an anolyte recycle loop configured to recirculate at least a portion of the anolyte;
a catholyte recycle loop configured to recirculate a least a portion of the catholyte;
an electrochemical acidification system configured to acidify the alkali metal formate to formic acid, the electrochemical acidification system including:
an electrochemical acidification unit including:
a catholyte compartment comprising a cathode;
an anolyte compartment comprising an anode; and
an ion exchange compartment positioned between the catholyte compartment and the anolyte compartment, the ion exchange compartment including an input port configured to receive the alkali metal formate from the electrolyzer,
wherein the electrochemical acidification unit is configured to produce formic acid upon application of an electrical potential between the anode and cathode of electrochemical acidification unit, and wherein said catholyte compartment is configured to produce an alkali metal hydroxide;
an alkali metal recycle system configured to receive the alkali metal hydroxide, and at least one of at least a portion of carbon dioxide generated from the electrochemical acidification system or at least a portion of residual carbon dioxide from the electrolyzer system, the alkali metal recycle system configured to generate at least a portion of the alkali metal bicarbonate solution fed to the second compartment of the electrolyzer.
19 . A high surface area electrode, comprising:
a substrate including at least one of a metal or carbon, the substrate having a void volume of between about 30% to 98%; and
an electrocatalyst coating disposed on the surface of the electrode, the electrocatalyst coating covering about 5% to 100% of the electrode surface area, the electrocatalyst coating including indium in an amount of about 5% to 99% by weight.
20 . The high surface area electrode of claim 19 , wherein the substrate includes copper.
21 . The high surface area electrode of claim 20 , further including:
a tin coating on the copper substrate.
22 . The high surface area electrode of claim 21 , wherein the indium is coated on the tin coating.
23 . The high surface area electrode of claim 19 , wherein the electrocatalyst includes indium as a metal alloy.
24 . The high surface area electrode of claim 23 , wherein the metal alloy includes indium as an alloy with one or more of Sn, Pb, Hg, Tl, Bi, Cu, and Cd, and alloy mixtures thereof.
25 . The high surface area electrode of claim 19 , wherein the electrocatalyst coating further includes one or more of Au, Ag, Zn, Pb, and Pd in an amount of about 5% to 99% by weight.
26 . The high surface area electrode of claim 19 , wherein the electrocatalyst coating further includes an oxide of one of or more of Au, Ag, Bi, Cu, Cd, Pb, Pd, Hg, Sn, Tl, Zn, and mixtures thereof.
27 . The high surface area electrode of claim 19 , wherein the electrocatalyst coating is disposed as a single layer on the substrate.
28 . The high surface area electrode of claim 19 , wherein the electrocatalyst coating is disposed as a plurality of layers on the substrate.
29 . The high surface area electrode of claim 28 , wherein the plurality of layers includes at least a first layer deposited on a second layer; the first layer including indium, and the second layer including at least one of Au, Ag, Bi, Cu, Cd, Pb, Pd, Hg, Sn, Tl, Zn, and mixtures thereof.
30 . The high surface area electrode of claim 19 , wherein the substrate comprises a specific surface area of about 2 cm 2 /cm 3 .