US2019010620A1PendingUtilityA1
Method And System For Electrochemical Production Of Formic Acid From Carbon Dioxide
Est. expiryOct 21, 2034(~8.3 yrs left)· nominal 20-yr term from priority
B01J 47/12B01J 41/14C25B 9/10C25B 3/04C25B 1/02C25B 1/00H01M 8/1053H01M 2300/0082Y02E60/366Y02P70/56C25B 15/02C25B 1/04H01M 8/1023C25B 13/08C25B 9/08C25B 15/08H01M 4/8668C25B 9/23C25B 3/25C25B 9/19Y02E60/50Y02P70/50Y02E60/36C25B 9/21C25B 3/26C25B 1/23C25B 3/07C25B 11/032
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Claims
Abstract
An electrochemical device converts carbon dioxide to a formic acid reaction product. The device includes an anode and a cathode, each comprising a quantity of catalyst. The anode and cathode each have reactant introduced thereto. A cation exchange polymer electrolyte membrane and an anion exchange polymer electrolyte membrane, are interposed between the anode and the cathode, forming a central flow compartment where a carbon dioxide reduction product, such as formic acid, can be recovered. At least a portion of the cathode catalyst is directly exposed to gaseous carbon dioxide during electrolysis. The average current density at the membrane is at least 20 mA/cm 2 , measured as the area of the cathode gas diffusion layer that is covered by catalyst, and formate ion selectivity is at least 50% at a cell potential difference of 3.0 V.
Claims
exact text as granted — not AI-modifiedWhat is claimed is:
1 . An electrochemical device for converting CO 2 to a reaction product, the device comprising:
(a) an anode comprising a quantity of anode catalyst, said anode having an anode reactant introduced thereto via at least one anode reactant flow channel; (b) a cathode comprising a quantity of cathode catalyst, said cathode having a cathode reactant introduced thereto via at least one cathode reactant flow channel; (c) a central flow compartment, located between said anode and said cathode having an inlet solution feed and an outlet solution product output; (d) a cation exchange membrane interposed between said anode and said central flow compartment; (e) an anion exchange membrane interposed between said central flow compartment and said cathode; and (f) a source of electrical energy that applies a potential difference across the anode and the cathode,
wherein said cathode is encased in a cathode chamber and at least a portion of the cathode catalyst is directly exposed to gaseous CO 2 during electrochemical conversion of the CO 2 to the reaction product and wherein said anion exchange membrane contacts said cathode.
2 . The electrochemical device of claim 1 , wherein said anion exchange membrane has oppositely facing first and second major surfaces, said first major surface contacts said cathode and said second major surface contacting an aqueous constituent.
3 . The electrochemical device of claim 1 , wherein said central flow compartment comprises an acidic medium.
4 . The electrochemical device in claim 3 , wherein the device satisfies a test comprising:
(1) with said anode open to atmospheric air, introducing a stream of CO 2 humidified at 50° C. into said cathode chamber while the device is at room temperature and atmospheric pressure; (2) applying a potential difference of 3.5 V across a cell via an electrical connection between said anode and said cathode with the device at room temperature; (3) measuring the current across said cell and the concentration and production rates of formic acid in said central flow compartment and production rate of CO and H 2 at the exit of said cathode chamber; (4) calculating the formate ion selectivity, Selectivity FO , as follows:
Selectivity
FO
=
(
Formate
ion
production
rate
)
(
CO
production
rate
+
H
2
production
rate
+
Formate
ion
production
rate
)
where the CO, H 2 and formate ion production rates are measured in moles per minute leaving the device.
(5) performing steps (1)-(4) with room temperature water being directed to said anode; and
(6) determining that the device has satisfied the test if the average current density at the membrane is at least 20 mA/cm 2 , where the cm 2 is measured as the area of said cathode gas diffusion layer on which said catalyst is disposed, and formate ion selectivity is at least 25% at a cell potential difference of 3.5 V.
5 . The electrochemical device in claim 1 , wherein at least 50% by mass of said cathode catalyst is directly exposed to gaseous CO 2 during electrochemical conversion of the CO 2 to said reaction product.
6 . The electrochemical device of claim 5 , wherein said gaseous CO 2 is directed within 2 mm of said cathode catalyst or said gas diffusion layer on which said cathode catalyst is disposed.
7 . The electrochemical device in claim 6 , wherein at least 90% by mass of said cathode catalyst is directly exposed to gaseous CO 2 during electrochemical conversion of the CO 2 to said reaction product.
8 . The electrochemical device in claim 1 , wherein said central flow compartment contains a structure comprising an ion exchange resin.
9 . The electrochemical device of claim 1 , wherein at least a portion of said anion exchange membrane is a Helper Membrane identifiable by applying a test comprising:
(1) preparing a cathode comprising 6 mg/cm 2 of silver nanoparticles on a carbon fiber paper gas diffusion layer; (2) preparing an anode comprising 3 mg/cm 2 of RuO 2 on a carbon fiber paper gas diffusion paper; (3) preparing a polymer electrolyte membrane test material; (4) interposing the membrane test material between said anode and said cathode, the side of said cathode having said silver nanoparticles disposed thereon facing one side of said membrane and the side of said anode having IrO 2 disposed thereon facing the other side of said membrane, thereby forming a membrane electrode assembly; (5) mounting said membrane electrode assembly in a fuel cell hardware assembly having cathode reactant flow channels and anode reactant flow channels; (6) directing a stream of CO 2 humidified at 50° C. into said cathode reactant flow channels while the fuel cell hardware assembly is at room temperature and atmospheric pressure, with said anode reactant flow channels left open to the atmosphere at room temperature and pressure; (7) applying a potential difference of 3.0 V across the cell via an electrical connection between said anode and said cathode; (8) measuring the current across the cell and the concentration of CO and H 2 at the exit of said cathode flow channel; (9) calculating the CO selectivity as follows:
Selectivity
=
(
CO
production
rate
)
(
CO
production
rate
+
H
2
production
rate
)
;
and where the CO and H 2 production rates are measured in moles per minute leaving the device;
(10) identifying said membrane as a Helper Membrane if the average current density at said membrane is at least 20 mA/cm 2 , where the cm 2 is measured as the area of said cathode gas diffusion layer that is covered by catalyst particles, and CO selectivity is at least 50% at a cell potential difference of 3.0 V.
10 . The electrochemical device of claim 9 , wherein said anion exchange membrane is entirely a Helper Membrane.
11 . The electrochemical device of claim 1 , wherein said anion exchange membrane comprises a polymer comprising at least one of:
(a) a positive charged cyclic amine, (b) an imidazolium, (c) a pyridinium, (d) a guanidinium, and (e) a phosphonium.
12 . The electrochemical device of claim 1 , wherein:
(a) said anode catalyst is applied as a coating on said cation exchange membrane, or as a coating on a substrate, wherein said anode catalyst is facing said cation exchange membrane, and (b) said cathode catalyst is applied as a coating on said anion exchange membrane, or as a coating on a substrate, wherein said cathode catalyst is facing said anion exchange membrane
13 . The electrochemical device of claim 1 , wherein the potential difference is 5 V or less.
14 . The electrochemical device of claim 1 , wherein said reaction product is selected from the group consisting of CO, HCO − , H 2 CO, (HCO 2 ) − , H 2 CO 2 , CH 3 OH, CH 4 , C 2 H 4 , CH 3 CH 2 OH, CH 3 COO − , CH 3 COOH, C 2 H 6 , (COOH) 2 , (COO − ) 2 , H 2 C═CHCOOH and CF 3 COOH.
15 . The electrochemical device of claim 1 , wherein said cathode catalyst further comprises a Catalytically Active Element.
16 . The electrochemical device of claim 15 , wherein said Catalytically Active Element is selected from the group consisting of Au, Ag, Cu, Sn, Sb, Bi, Pb, Zn and In.
17 . The electrochemical device of claim 1 , wherein said anode catalyst further comprises a Catalytically Active Element.
18 . The electrochemical device of claim 17 , wherein said Catalytically Active Element is selected from the group consisting of Pt, Ru and Ir.
19 . The electrochemical device in claim 1 , wherein said anion exchange membrane comprises a polymer in which at least one constituent monomer is (p-vinylbenzyl)-R, where R is selected from the group consisting of positively charged cyclic amines, imidazoliums, pyridiniums and phosphoniums, and wherein said membrane comprises 15%-90% by weight of polymerized (p-vinylbenzyl)-R.
20 . The electrochemical device of claim 19 , wherein said anion exchange membrane comprises a polymer in which at least one constituent monomer is styrene.
21 . The electrochemical device of claim 19 , wherein said anion exchange membrane has a thickness of 25-1000 micrometers.
22 . The electrochemical device of claim 21 , wherein said anion exchange membrane further comprises a copolymer of at least one of methyl methacrylate and butylacrylate.
23 . The electrochemical device of claim 20 , wherein said anion exchange membrane further comprises at least one of a polyolefin, a chlorinated polyolefin, a fluorinated polyolefin, and a polymer comprising at least one of cyclic amines, phenyls, nitrogen and carboxylate (—COO—) groups in its repeating unit.
24 . The electrochemical device of claim 19 , wherein R is selected from at least one of:
(a) imidazoliums of the formula:
where R 1 -R 5 are each independently selected from the group consisting of hydrogen, halides, linear alkyls, branched alkyls, cyclic alkyls, heteroalkyls, aryls, heteroaryls, alkylaryls, heteroalkylaryls, and polymers thereof;
(b) pyridiniums of the formula:
where R 6 -R 11 are each independently selected from the group consisting of hydrogen, halides, linear alkyls, branched alkyls, cyclic alkyls, heteroalkyls, aryls, heteroaryls, alkylaryls, heteroalkylaryls, and polymers thereof; and
(c) phosphoniums of the formula:
P + (R 12 R 13 R 14 R 15 )
where R 12 -R 15 are each independently selected from the group consisting of hydrogen, halides, linear alkyls, branched alkyls, cyclic alkyls, heteroalkyls, aryls, heteroaryls, alkylaryls, heteroalkylaryls, and polymers thereof.
25 . The electrochemical device of claim 24 , wherein R is an imidazolium, pyridinium or polymer thereof wherein no aromatic nitrogen is attached to hydrogen.
26 . An electrochemical device for converting CO 2 to a reaction product, the device comprising:
(a) an anode comprising a quantity of anode catalyst, said anode having an anode reactant introduced thereto via at least one anode reactant flow channel; (b) a cathode comprising a quantity of cathode catalyst, said cathode having a cathode reactant introduced thereto via at least one cathode reactant flow channel; (c) a central flow compartment, located between said anode and said cathode having an inlet solution feed and an outlet solution product output; (d) a cation exchange membrane interposed between said anode and said central flow compartment; and (e) an anion exchange membrane interposed between said central flow compartment and said cathode;
wherein said cathode is encased in a cathode chamber and at least a portion of said cathode catalyst is directly exposed to gaseous CO 2 during conversion of CO 2 to a reaction product, wherein said cathode comprises a cathode catalyst layer comprising an anion exchange polymer and wherein said anion exchange membrane contacts said cathode.
27 . The electrochemical device in claim 26 , wherein said gaseous CO 2 is humidified.
28 . The electrochemical device of claim 26 , wherein the reaction current is higher with said anion exchange polymer in said cathode catalyst layer than without said anion exchange polymer in said cathode catalyst layer.
29 . The electrochemical device of claim 26 , wherein the selectivity to a desired product is higher with said anion exchange polymer in said cathode catalyst layer than without said anion exchange polymer in said cathode catalyst layer.
30 . The electrochemical device of claim 26 , wherein the CO 2 reaction product is selected from the group consisting of CO, HCO − , H 2 CO, (HCO 2 ) − , H 2 CO 2 , CH 3 OH, CH 4 , C 2 H 4 , CH 3 CH 2 OH, CH 3 COO − , CH 3 COOH, C 2 H 6 , (COOH) 2 , (COO − ) 2 , H 2 C═CHCOOH, and CF 3 COOH.
31 . The electrochemical device of claim 29 , wherein the CO 2 reaction product is the formate ion or formic acid.
32 . The electrochemical device of claim 26 , wherein said cathode catalyst further comprises a Catalytically Active Element.
33 . The electrochemical device of claim 32 , wherein said Catalytically Active Element is selected from the group consisting of Au, Ag, Cu, Sn, Sb, Bi, Pb, Zn and In.
34 . The electrochemical device of claim 26 , wherein said anode catalyst further comprises a Catalytically Active Element.
35 . The electrochemical device of claim 34 , wherein said Catalytically Active Element is selected from the group consisting of Pt, Ru and Ir.
36 . The electrochemical device of claim 26 , wherein said anion exchange polymer of said cathode catalyst layer comprises a polymer in which at least one constituent monomer is (p-vinylbenzyl)-R, where R is selected from the group consisting of imidazoliums, pyridiniums and phosphoniums, and wherein said membrane comprises 15%-90% by weight of polymerized (p-vinylbenzyl)-R.
37 . The electrochemical device of claim 36 , wherein said anion exchange polymer comprises a polymer in which at least one constituent monomer is styrene.
38 . The electrochemical device of claim 26 , wherein said anion exchange membrane interposed between said central flow compartment and said cathode has a thickness of 25-1000 micrometers.
39 . The electrochemical device of claim 36 , wherein said anion exchange polymer of said cathode catalyst layer further comprises a copolymer of at least one of methyl methacrylate and butylacrylate.
40 . The electrochemical device of claim 36 , wherein said anion exchange polymer of said cathode catalyst layer further comprises at least one of a polyolefin, a chlorinated polyolefin, a fluorinated polyolefin, and a polymer selected from the group consisting of cyclic amines, phenyls, nitrogen and carboxylate (—COO—) groups in its repeating unit.
41 . The electrochemical device of claim 36 , wherein R is selected from at least one of:
(a) imidazoliums of the formula:
where R 1 -R 5 are each independently selected from the group consisting of hydrogen, halides, linear alkyls, branched alkyls, cyclic alkyls, heteroalkyls, aryls, heteroaryls, alkylaryls, heteroalkylaryls, and polymers thereof;
(b) pyridiniums of the formula:
where R 6 -R 11 are each independently selected from the group consisting of hydrogen, halides, linear alkyls, branched alkyls, cyclic alkyls, heteroalkyls, aryls, heteroaryls, alkylaryls, heteroalkylaryls, and polymers thereof; and
(c) phosphoniums of the formula:
P + (R 12 R 13 R 14 R 15 )
where R 12 -R 15 are each independently selected from the group consisting of hydrogen, halides, linear alkyls, branched alkyls, cyclic alkyls, heteroalkyls, aryls, heteroaryls, alkylaryls, heteroalkylaryls, and polymers thereof.
42 . The electrochemical device of claim 41 , wherein R is an imidazolium, pyridinium or polymer thereof, wherein no aromatic nitrogen is attached to hydrogen.Cited by (0)
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