CO2 PURIFICATION AND REDUCTION SYSTEMS
A CO 2 purifier and a CO 2 electrolyzer may be integrated in a single electrochemical unit or cell having a bipolar plate separating the purifier and electrolyzer. In some embodiments, the electrochemical cell has a single positive electrical terminal attached to an anode of the CO 2 electrolyzer or the CO 2 purifier, and a single negative electrical terminal attached to a cathode of the CO 2 electrolyzer or the CO 2 purifier. In such implementations a bipolar plate may serve as a counter-electrode for both the CO 2 electrolyzer and the CO 2 purifier.
1 . A system comprising:
(a) a first outer electrode of a first polarity;
(b) a CO 2 purifier comprising:
(i) an inlet for receiving impure CO 2,
(ii) the first outer electrode configured to apply an electrical potential of a first polarity,
(iii) a medium that selectively captures and/or removes CO 2 under the influence of a positive electrical potential or a negative electrical potential, and
(iv) an outlet for removing purified CO 2 ;
(c) a second outer electrode configured to apply an electrical potential of a second polarity, opposite the first polarity;
(d) a CO 2 electrolyzer configured to receive the purified CO 2 from the CO 2 purifier, the CO 2 electrolyzer comprising:
(i) an inlet for receiving the purified CO 2 ,
(ii) the second outer electrode, and
(iii) a cathode catalyst configured to electrochemically reduce CO 2 to produce a carbon containing product; and
(e) a bipolar plate separating the CO 2 purifier from the CO 2 electrolyzer and arranged to provide (i) a first bipolar electrode surface of the second polarity for the CO 2 purifier, and (ii) a second bipolar electrode surface of the first polarity for the CO 2 electrolyzer.
2 . The system of claim 1 , wherein the bipolar plate does not have an electrical connection to an external circuit or load.
3 . The system of claim 1 , wherein the CO 2 purifier is configured to produce the purified CO 2 while electrical energy is supplied to the first outer electrode and the second outer electrode.
4 . The system of claim 3 , wherein the CO 2 purifier is configured to continuously produce the purified CO 2 .
5 . The system of claim 1 , wherein the CO 2 purifier comprises a plurality of parallel liquid flow paths between the bipolar plate and the first outer electrode, wherein the plurality of parallel liquid flow paths comprise:
a carbonate donating flow path configured to flow a first solution containing carbonate and/or bicarbonate ions wherein the carbonate donating flow path is bounded on a first side by an anion exchange membrane, and
a carbonate receiving flow path arranged adjacent to said carbonate donating flow path and configured to flow a second solution that is more acidic than the first solution, wherein the carbonate receiving flow path is bounded by said anion exchange membrane that allows the carbonate and/or bicarbonate ions to pass from the carbonate donating flow path to the carbonate receiving flow path, and
wherein the medium comprises the first solution and/or the second solution.
6 . The system of claim 5 , wherein the carbonate donating flow path is bounded on a second side by a bipolar membrane.
7 . The system of claim 5 , wherein the carbonate receiving flow path is bounded by a bipolar membrane.
8 . The system of claim 5 , wherein the plurality of parallel liquid flow paths further comprise:
a second carbonate donating flow path configured to flow the first solution; and
a second carbonate receiving flow path arranged adjacent to said second carbonate donating flow path and configured to flow the second solution.
9 . The system of claim 5 , further comprising a first solution tank configured to supply the first solution to the carbonate donating flow path and a recycle path configured to recycle the first solution from the carbonate donating flow path to the first solution tank.
10 . The system of claim 5 , further comprising a second solution tank configured to supply the second solution to the carbonate receiving flow path and a recycle path configured to recycle the second solution from the carbonate receiving flow path to the second solution tank.
11 . The system of claim 1 , wherein the CO 2 purifier comprises
one or more flow paths configured transport a compound comprising one or more electroactive CO 2 -absorbing moieties between an anode region and a cathode region, and
a controller configured to
apply a cathodic potential and/or flow a cathodic current to the cathode region to thereby cause the compound to absorb CO 2 from the impure CO 2 ,
apply an anodic potential and/or flow an anodic current to the anode region to thereby cause the compound to release CO 2 and produce the purified CO 2 , and
cause the compound to move between the cathode region and the anode region.
12 . The system of claim 11 , wherein the CO 2 purifier further comprises a separator between the cathode region and the anode region.
13 . The system of claim 11 , wherein the compound comprises one or more electroactive CO 2 -absorbing moieties is a polymer.
14 . The system of claim 11 , wherein the one or more CO 2 -absorbing moieties comprise quinone moieties.
15 . The system of claim 1 , wherein the CO 2 electrolyzer comprises a membrane electrode assembly (MEA).
16 . The system of claim 15 , wherein the MEA comprises an anion conducting polymer membrane.
17 . The system of claim 16 , wherein the MEA further comprises a cation conducting polymer membrane in contact with the anion conducting polymer membrane.
18 . The system of claim 1 , wherein the carbon containing product comprises CO, a hydrocarbon, formic acid, an alcohol, or any combination thereof.
19 . The system of claim 1 , further comprising a controller configured to cause electrical energy to be applied to the first outer electrode and the second outer electrode and thereby cause:
the CO 2 purifier to produce the purified CO 2 , and
the cathode catalyst to electrochemically reduce the purified CO 2 to produce the carbon containing product.
20 . The system of claim 1 , wherein the purified CO 2 has a concentration of at least about 20% by volume.
21 . A method of electrochemically reducing CO 2 to a carbon containing product using a system comprising (a) a first outer electrode of a first polarity, (b) a second outer electrode of a second polarity, opposite the first polarity, (c) a CO 2 purifier having the first outer electrode as a CO 2 purifier anode or cathode, (d) a CO 2 electrolyzer having the second outer electrode as a CO 2 electrolyzer anode or cathode, and (e) a bipolar plate separating the CO 2 purifier from the CO 2 electrolyzer and arranged to provide (i) a first bipolar electrode surface of the second polarity for the CO 2 purifier, and (ii) a second bipolar electrode surface of the first polarity for the CO 2 electrolyzer, the method comprising:
receiving impure CO 2 in the CO 2 purifier;
selectively capturing and/or removing CO 2 under the influence of a positive electrical field or a negative electrical field in the CO 2 purifier;
providing purified CO 2 from the CO 2 purifier to the CO 2 electrolyzer; and
electrochemically reducing the purified CO 2 in the CO 2 electrolyzer to produce a carbon containing product.
22 . The method of claim 21 , wherein the bipolar plate does not have an electrical connection to an external circuit or load.
23 . The method of claim 21 , wherein selectively capturing and/or removing CO 2 comprises supplying electrical energy to the first outer electrode and the second outer electrode.
24 . The method of claim 23 , wherein the CO 2 purifier continuously provides the purified CO 2 to the CO 2 electrolyzer.
25 . The method of claim 21 , wherein the CO 2 purifier comprises a plurality of parallel liquid flow paths between the bipolar plate and the first outer electrode, wherein the plurality of parallel liquid flow paths comprise:
a carbonate donating flow path that flows a first solution containing carbonate and/or bicarbonate ions and is bounded on a first side by an anion exchange membrane, and
a carbonate receiving flow path adjacent to said carbonate donating flow path and flows a second solution that is more acidic than the first solution, wherein the carbonate receiving flow path is bounded by said anion exchange membrane that allows the carbonate and/or bicarbonate ions to pass from the carbonate donating flow path to the carbonate receiving flow path.
26 . The method of claim 25 , wherein the carbonate donating flow path is bounded on a second side by a bipolar membrane.
27 . The method of claim 25 , wherein the carbonate receiving flow path is bounded by a bipolar membrane.
28 . The method of claim 25 , wherein the plurality of parallel liquid flow paths further comprise:
a second carbonate donating flow path configured to flow the first solution; and
a second carbonate receiving flow path arranged adjacent to said second carbonate donating flow path and configured to flow the second solution.
29 . The method of claim 25 , further comprising:
supplying the first solution to the carbonate donating flow path from a first solution tank; and
recycling the first solution from the carbonate donating flow path to the first solution tank.
30 . The method of claim 25 , further comprising:
supplying the second solution to the carbonate receiving flow path from a second solution tank; and
recycling the second solution from the carbonate receiving flow path to the second solution tank.
31 . The method of claim 21 , further comprising:
transporting a compound comprising one or more electroactive CO 2 -absorbing moieties between an anode region of the CO 2 purifier and a cathode region of the CO 2 purifier;
applying a cathodic potential and/or flowing a cathodic current to the cathode region to thereby cause the compound to absorb CO 2 from the impure CO 2 ;
applying an anodic potential and/or flowing an anodic current to the anode region to thereby cause the compound to release CO 2 and produce the purified CO 2 ; and
moving the compound between the cathode region and the anode region.
32 . The method of claim 31 , wherein the CO 2 purifier further comprises a separator between the cathode region and the anode region.
33 . The method of claim 31 , wherein the compound comprises one or more electroactive CO 2 -absorbing moieties is a polymer.
34 . The method of claim 31 , wherein the one or more CO 2 -absorbing moieties comprise quinone moieties.
35 . The method of claim 21 , wherein the CO 2 electrolyzer comprises a membrane electrode assembly (MEA).
36 . The method of claim 35 , wherein the MEA comprises an anion conducting polymer membrane.
37 . The method of claim 36 , wherein the MEA further comprises a cation conducting polymer membrane in contact with the anion conducting polymer membrane.
38 . The method of claim 21 , wherein the carbon containing product comprises CO, a hydrocarbon, formic acid, an alcohol, or any combination thereof.
39 . The method of claim 21 , further comprising:
applying electrical energy to the first outer electrode and the second outer electrode and thereby cause:
the CO 2 purifier to produce the purified CO 2 , and the CO 2 electrolyzer to electrochemically reduce the purified CO 2 to produce the carbon containing product.
40 . The method of claim 21 , wherein the purified CO 2 has a concentration of at least about 20% by volume.