Systems and methods for electrochemical carbon dioxide reduction in iron production

Abstract

Provided herein are methods of producing iron compositions, methods of converting carbon dioxide from a process gas into carbon monoxide and hydrogen, and systems for producing iron compositions.

Description

[0001] Attorney Docket No.: HCV-00125

[0002] SYSTEMS AND METHODS FOR ELECTROCHEMICAL CARBON DIOXIDE REDUCTION IN IRON PRODUCTION

[0003] CROSS-REFERENCE TO RELATED APPLICATIONS

[0004] This application claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 720,966, filed November 15, 2024, the entire contents of which are incorporated by reference herein.

[0005] BACKGROUND

[0006] Carbon dioxide emissions from the conversion of iron ore into iron, e.g., as part of the process of steel production, represent a major contributor to global carbon dioxide emissions. The reduction process required to convert iron oxide from ores into metallic iron is frequently conducted in the presence of a reducing gas comprising a carbon-containing component (e.g., a mixture of hydrogen with carbon monoxide and / or light hydrocarbons), which results in iron products incorporating carbon, such as “pig iron” or “crude iron,” which is a critical component of steel materials. However, the process of incorporating the carbon into the iron during reduction produces a process gas or “top gas” comprising large amounts of carbon dioxide which must either be released or captured using expensive off-taking methods. Additionally, legacy processes that provide the carbon-containing reducing gas involve the use of fossil fuels to product synthesis gas (a mixture of hydrogen and carbon monoxide), which is also highly energy- and emissions-intensive. Accordingly, there exists a need both to reduce carbon dioxide emissions from the production of carbonized iron, and to provide a reducing gas comprising carbon monoxide and hydrogen without the use of legacy syngas processes.

[0007] SUMMARY OF THE INVENTION

[0008] In certain aspects, the present disclosure provides methods for producing an iron composition, the method comprising:

[0009] reacting a source of iron oxide with a reducing gas feed comprising carbon monoxide and hydrogen in a reduction reactor to produce the iron product and a process gas comprising carbon dioxide and water;

[0010] optionally, combining the process gas with water to produce a humidified process gas; contacting the process gas or the humidified process gas with a cathode of an electrolyzer while applying a voltage across the cathode and the anode, wherein the electrolyzer comprises:

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[0012] an anode chamber comprising an anode;

[0013] a cathode chamber comprising the cathode; and

[0014] a membrane separator disposed between and configured to separate the anode chamber from the cathode chamber;

[0015] wherein the anode chamber and the cathode chamber are in ionic communication;

[0016] thereby producing carbon monoxide and hydrogen; and

[0017] optionally, transferring the carbon monoxide and hydrogen to the reduction reactor. In further aspects, provided herein are methods for the reduction of carbon dioxide comprising:

[0018] optionally, combining process gas comprising carbon dioxide with water to produce a humidified process gas;

[0019] contacting the process gas or the humidified process gas with a cathode of an electrolyzer while applying a voltage across the cathode and the anode, wherein the electrolyzer comprises:

[0020] an anode chamber comprising an anode;

[0021] a cathode chamber comprising a cathode; and

[0022] a membrane separator disposed between and configured to separate the anode chamber from the cathode chamber;

[0023] and wherein the anode chamber and the cathode chamber are in ionic communication; thereby producing a reducing gas comprising carbon monoxide and hydrogen.

[0024] In yet further aspects, provided herein are systems for producing an iron composition, comprising:

[0025] a reduction reactor comprising:

[0026] a first process gas outlet;

[0027] a first reducing gas inlet;

[0028] an iron oxide source inlet;

[0029] an iron product outlet;

[0030] an electrolyzer comprising:

[0031] an anode chamber comprising

[0032] an anode;

[0033] a cathode chamber comprising;

[0034] a cathode;

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[0036] a first process gas inlet coupled to the first process gas outlet of the reduction reactor;

[0037] a first reducing gas outlet optionally coupled to the first reducing gas inlet of the reduction reactor;

[0038] a membrane disposed between and configured to separate the anode chamber from the cathode chamber;

[0039] wherein the anode chamber and the cathode chamber are in ionic communication; and optionally, wherein the first reducing gas outlet of the electrolyzer is coupled to the first reducing gas inlet of the reduction reactor.

[0040] BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Fig. 1 shows a schematic of an exemplary system of the disclosure. The arrowheads indicate direction of flow of the various process streams.

[0042] Fig. 2 shows a schematic of an exemplary system of the disclosure. The arrowheads indicate direction of flow of the various process streams.

[0043] Fig. 3 shows an exploded schematic view of an exemplary electrolyzer cell assembly. Fig. 4 shows a diagram of an exemplary electrolyzer system including a gas stream humidifier, power supply, anolyte reservoir, and electrolyzer. The arrowheads indicate direction of flow of the various process streams.

[0044] Fig. 5 is a graph comparing the compositions of the blast furnace top gas (left) and cathodic output gas (right) from the electrochemical reactor of an exemplary system as shown in Fig. 7.

[0045] Fig. 6 is a graph comparing the compositions of the shaft furnace top gas (left) and cathodic output gas (right) from the electrochemical reactor of an exemplary system as shown in Fig. 1.

[0046] Fig. 7 shows a schematic of an exemplary system of the disclosure. The arrowheads indicate direction of flow of the various process streams. BFG = blast furnace top gas.

[0047] DETAILED DESCRIPTION OF THE INVENTION

[0048] Methods of Producing Iron Compositions

[0049] In certain aspects, the present disclosure provides methods for producing an iron composition, the method comprising:

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[0051] reacting a source of iron oxide with a reducing gas feed comprising carbon monoxide and hydrogen in a reduction reactor to produce the iron product and a process gas comprising carbon dioxide and water;

[0052] optionally, combining the process gas with water to produce a humidified process gas; contacting the process gas or the humidified process gas with a cathode of an electrolyzer while applying a voltage across the cathode and the anode, wherein the electrolyzer comprises:

[0053] an anode chamber comprising an anode;

[0054] a cathode chamber comprising the cathode; and

[0055] a membrane separator disposed between and configured to separate the anode chamber from the cathode chamber;

[0056] wherein the anode chamber and the cathode chamber are in ionic communication;

[0057] thereby producing carbon monoxide and hydrogen; and

[0058] optionally, transferring the carbon monoxide and hydrogen to the reduction reactor. As will be appreciated by one of ordinary skill in the art, it is generally desirable to use a reducing gas comprising both carbon monoxide and hydrogen in the conversion of a source of iron oxide to an iron composition, as opposed to performing analogous methods using a reducing gas that comprises no carbon monoxide (or does not comprise a substantial amount of carbon monoxide). Reducing gases that comprise insufficient amounts of a carbon source (e.g. carbon monoxide) can reduce furnace efficiency due to the endothermic reaction of hydrogen and iron ore, and produce iron compositions of a lower quality (e.g., a lower carbon content resulting in higher remelting energy requirements). As such, the methods provided herein, which in some embodiments allow for the conversion of carbon dioxide from a process gas (e.g. top gas from a metal ore reduction reactor, preferably an iron reduction reactor) to carbon monoxide and hydrogen, provide important advantages over analogous methods that do not involve produce CO.

[0059] In cyclical processes, as are the presently disclosed methods, it may be necessary to initially deliver a fixed amount of externally produced reducing gas (CO / H2) to the reduction reactor to initiate the reaction before the electrolyzer has started producing the reducing gas. Similarly, it may be necessary to initially deliver a fixed amount of externally produced carbon dioxide to the electrolyzer to initiate the reaction before the reduction reactor has started producing the process gas. Those of skill in the art will be familiar with the general conditions under which such initial gas delivery may be necessary, as well as methods for doing so. Once - 4 - FH13150382.3 Attorney Docket No.: HCV-00125

[0060] the process is initiated, such external delivery may no longer be required, and thus the presently disclosed processes still afford advantages over traditional processes which require constant introduction of externally produced reducing gas and / or carbon dioxide. Additionally, fossil-derived reduction gas may be blended with the electrolytically produced reduction gas in the system as needed throughout the process to tune system operation and efficiency. In other embodiments, once in operation, the system can be operated in an entirely or substantially closed-loop manner.

[0061] In certain embodiments, methods of the disclosure comprise combining the process gas with water to produce a humidified process gas. In further embodiments, methods of the disclosure comprise contacting the humidified process gas with the cathode of the electrolyzer.

[0062] In certain embodiments, methods of the disclosure further comprise collecting the carbon monoxide and hydrogen. In some embodiments, methods of the disclosure comprise transferring the carbon monoxide and hydrogen to the reduction reactor. In further embodiments, transferring the reducing gas to the reduction reactor further comprises preheating the reducing gas. In yet further embodiments, the reducing gas is pre-heated to at least about 700 °C. In still further embodiments, the reducing gas is pre-heated to at least about 750 °C. In certain embodiments, the reducing gas is pre-heated to from about 750 °C to about 1250 °C. In yet further embodiments, transferring the reducing gas to the reduction reactor further comprises combining the reducing gas with a carrier gas (e.g., air, He, N2, or Ar).

[0063] In certain embodiments, methods of the disclosure further comprise flowing a cooling fluid through the reduction reactor. In further embodiments, methods of the disclosure further comprise flowing a cooling gas through the reduction reactor. In yet further embodiments, methods of the disclosure further comprise flowing a cooling liquid through the reduction reactor. In some embodiments, methods of the disclosure further comprise flowing a carrier gas through the reduction reactor.

[0064] In certain embodiments, the iron composition comprises iron and carbon.

[0065] In certain embodiments, the reduction reactor comprises a Smelting Reduction Furnace, Direct Reduction of Iron (DRI) reactor, shaft furnace, blast furnace, or rotary kiln. In some embodiments, the reduction reactor comprises a tube furnace. In further embodiments, the reduction reactor is configured to produce hot-briquetted iron (HBI).

[0066] In certain embodiments, the source of iron oxide is an iron ore, optionally wherein the iron ore is in a form of lumps, pellets, or particles (e.g. , fines).

[0067] In certain embodiments, methods of the disclosure further comprise producing oxygen at the anode. In further embodiments, methods of the disclosure further comprise collecting the - 5 - FH13150382.3 Attorney Docket No.: HCV-00125

[0068] oxygen from the anode chamber. In yet further embodiments, methods of the disclosure further comprise transferring the oxygen from the anode chamber to the reduction reactor. In other embodiments, methods of the disclosure further comprise transferring the oxygen from the anode chamber to a furnace, e.g., an electric arc furnace or basic oxygen furnace. In further embodiments, methods of the disclosure further comprise transferring the oxygen from the anode chamber to an electric arc furnace. In yet further embodiments, methods of the disclosure further comprise transferring the oxygen from the anode chamber to a basic oxygen furnace.

[0069] In certain embodiments, methods of the disclosure further comprise passing the process gas or the humified process gas through a heat exchanger prior to contacting the process gas or humidified process gas with the cathode.

[0070] In certain embodiments, all of the hydrogen in the reducing gas is produced within the cathode chamber of the electrolyzer. In some embodiments, carbon monoxide and hydrogen are produced at the cathode. In further embodiments, carbon monoxide and hydrogen are both produced at the same cathode. In yet further embodiments, the cathode is configured to simultaneously produce carbon monoxide and hydrogen. In still further embodiments, carbon monoxide and hydrogen are both produced in the same electrolyzer. In certain embodiments, carbon monoxide and hydrogen are both produced at the same cathode. In further embodiments, carbon monoxide and hydrogen are simultaneously produced at the same cathode. In such embodiments, as will be appreciated by one of skill in the art, the present methods afford the advantage of not requiring an external hydrogen source (e.g., an additional electrolyzer configured to produce hydrogen).

[0071] In certain embodiments, the reducing gas is substantially free of hydrocarbons. In some embodiments, the methods provided herein do not comprise producing hydrocarbons at the cathode.

[0072] In certain embodiments, the process gas further comprises at least one gas selected from hydrogen (H2), carbon monoxide (CO), nitrogen (N2), methane (CH4), and a combination thereof. In certain embodiments, methods of the disclosure further comprise removing nitrogen oxides and sulfur oxides from the process gas. In certain embodiments, methods of the disclosure further comprise removing particulates from the process gas. In certain embodiments, methods of the disclosure do not comprise contacting the process gas with a gas separation system (e.g., Amine Absorption, Adsorption (PSA, TSA, or VSA), Cryogenics, or Membranes).

[0073] In certain embodiments, the membrane is an anion exchange membrane. In certain embodiments, the membrane is a bipolar membrane. In further embodiments, the bipolar - 6 - FH13150382.3 Attorney Docket No.: HCV-00125

[0074] membrane comprises an anion exchange layer and a cation exchange layer. In yet further embodiments, the bipolar membrane is configured to operate in forward bias. In other embodiments, the bipolar membrane is configured to operate in reverse bias. In certain embodiments, the method further comprises producing H+ions and OH“ ions within the bipolar membrane, and wherein the bipolar membrane is configured to allow the H+ions to flow to the cathode chamber and the OH" ions to flow to the anode chamber. In other embodiments, the method further comprises producing OH“, HCOa-, or COa2-, or a combination thereof, at the cathode, and producing H+at the anode, and the bipolar membrane is configured to allow the OH“, HCOa-, CO32" ions to flow from the cathode chamber and the H+ions to flow from the anode chamber.

[0075] In certain embodiments, methods of the disclosure do not comprise reducing carbon dioxide to carbon monoxide at the anode.

[0076] In certain embodiments, the anode does not comprise gold.

[0077] In certain embodiments, methods of the disclosure do not comprise concentrating carbon dioxide in the process gas.

[0078] In certain embodiments, methods of the disclosure do not comprise concentrating carbon dioxide in the humidified process gas.

[0079] In certain embodiments, the process gas comprises from about 1 wt% to about 100 wt% carbon dioxide. In further embodiments, the process gas comprises from about 1 wt% to about 40 wt% carbon dioxide. In yet further embodiments, the process gas comprises from about 40 wt% to about 90 wt% carbon dioxide. In still further embodiments, the process gas comprises from about 90 wt% to about 100 wt% carbon dioxide. In certain embodiments, the process gas comprises about 1 wt% carbon dioxide. In further embodiments, the process gas comprises about 5 wt% carbon dioxide. In yet further embodiments, the process gas comprises about 10 wt% carbon dioxide. In still further embodiments, the process gas comprises about 15 wt% carbon dioxide. In certain embodiments, the process gas comprises about 20 wt% carbon dioxide. In further embodiments, the process gas comprises about 25 wt% carbon dioxide. In yet further embodiments, the process gas comprises about 30 wt% carbon dioxide. In still further embodiments, the process gas comprises about 35 wt% carbon dioxide. In certain embodiments, the process gas comprises about 40 wt% carbon dioxide. In further embodiments, the process gas comprises about 45 wt% carbon dioxide. In yet further embodiments, the process gas comprises about 50 wt% carbon dioxide. In still further embodiments, the process gas comprises about 55 wt% carbon dioxide. In certain embodiments, the process gas comprises about 60 wt% carbon dioxide. In further - 7 - FH13150382.3 Attorney Docket No.: HCV-00125

[0080] embodiments, the process gas comprises about 65 wt% carbon dioxide. In yet further embodiments, the process gas comprises about 70 wt% carbon dioxide. In still further embodiments, the process gas comprises about 75 wt% carbon dioxide. In certain embodiments, the process gas comprises about 80 wt% carbon dioxide. In further embodiments, the process gas comprises about 85 wt% carbon dioxide. In yet further embodiments, the process gas comprises about 90 wt% carbon dioxide. In still further embodiments, the process gas comprises about 95 wt% carbon dioxide. In certain embodiments, the process gas comprises or about 100 wt% carbon dioxide.

[0081] In certain embodiments, the process gas comprises from about 5 parts per thousand to about 500 parts per thousand carbon dioxide. In further embodiments, the process gas comprises from about 5 parts per thousand to about 50 parts per thousand carbon dioxide. In yet further embodiments, the process gas comprises from about 50 parts per thousand to about 100 parts per thousand carbon dioxide. In still further embodiments, the process gas comprises from about 100 parts per thousand to about 150 parts per thousand carbon dioxide. In certain embodiments, the process gas comprises from about 150 parts per thousand to about 200 parts per thousand carbon dioxide. In further embodiments, the process gas comprises from about 200 parts per thousand to about 250 parts per thousand carbon dioxide. In yet further embodiments, the process gas comprises from about 250 parts per thousand to about 300 parts per thousand carbon dioxide. In still further embodiments, the process gas comprises from about 300 parts per thousand to about 350 parts per thousand carbon dioxide. In certain embodiments, the process gas comprises from about 350 parts per thousand to about 400 parts per thousand carbon dioxide. In further embodiments, the process gas comprises from about 400 parts per thousand to about 450 parts per thousand carbon dioxide. In yet further embodiments, the process gas comprises from about 450 parts per thousand to about 500 parts per thousand carbon dioxide.

[0082] In certain embodiments, methods of the disclosure result in essentially no carbon dioxide emissions.

[0083] In certain embodiments, the anode chamber further comprises an anolyte inlet and an anolyte outlet.

[0084] In certain embodiments, the reduction reactor and electrolyzer are configured according to Fig. 1.

[0085] In certain embodiments, the reduction reactor and electrolyzer are configured according to Fig. 2.

[0086] In certain embodiments, the electrolyzer is configured according to Fig. 3.

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[0088] In certain embodiments, the electrolyzer is configured according to Fig. 4.

[0089] In certain embodiments, provided herein is an iron composition, prepared according to a method of the present disclosure.

[0090] Methods of Converting Carbon Dioxide from Process Gas to Carbon Monoxide and Hydrogen In certain aspects, provided herein are methods for the reduction of carbon dioxide comprising:

[0091] optionally, combining process gas comprising carbon dioxide with water to produce a humidified process gas;

[0092] contacting the process gas or the humidified process gas with a cathode of an electrolyzer while applying a voltage across the cathode and the anode, wherein the electrolyzer comprises:

[0093] an anode chamber comprising an anode;

[0094] a cathode chamber comprising a cathode; and

[0095] a membrane separator disposed between and configured to separate the anode chamber from the cathode chamber;

[0096] and wherein the anode chamber and the cathode chamber are in ionic communication; thereby producing a reducing gas comprising carbon monoxide and hydrogen.

[0097] In certain embodiments, methods of the disclosure further comprise contacting an aqueous electrolyte solution with the anode.

[0098] In certain embodiments, methods of the disclosure further comprise producing oxygen at the anode. In further embodiments, methods of the disclosure further comprise collecting the oxygen from the anode chamber. In yet further embodiments, methods of the disclosure further comprise transferring the oxygen from the anode chamber to a reduction reactor. In other embodiments, methods of the disclosure further comprise transferring the oxygen from the anode chamber to a furnace, e.g., an electric arc furnace or basic oxygen furnace. In further embodiments, methods of the disclosure further comprise transferring the oxygen from the anode chamber to an electric arc furnace. In yet further embodiments, methods of the disclosure further comprise transferring the oxygen from the anode chamber to a basic oxygen furnace.

[0099] In certain embodiments, all of the hydrogen in the reducing gas is produced within the cathode chamber of the electrolyzer. In some embodiments, carbon monoxide and hydrogen are produced at the cathode. In further embodiments, carbon monoxide and hydrogen are both produced at the same cathode. In yet further embodiments, the cathode is configured to simultaneously produce carbon monoxide and hydrogen. In still further embodiments, carbon - 9 - FH13150382.3 Attorney Docket No.: HCV-00125

[0100] monoxide and hydrogen are both produced in the same electrolyzer. In certain embodiments, carbon monoxide and hydrogen are both produced at the same cathode. In further embodiments, carbon monoxide and hydrogen are simultaneously produced at the same cathode. In such embodiments, as will be appreciated by one of skill in the art, the present methods afford the advantage of not requiring an external hydrogen source (e.g., an additional electrolyzer configured to produce hydrogen).

[0101] In certain embodiments, the reducing gas is substantially free of hydrocarbons. In some embodiments, the methods provided herein do not comprise producing hydrocarbons at the cathode.

[0102] In certain embodiments, the process gas further comprises at least one gas selected from hydrogen (H2), carbon monoxide (CO), nitrogen (N2), methane (CH4), and a combination thereof. In certain embodiments, methods of the disclosure further comprise removing nitrogen oxides and sulfur oxides from the process gas. In certain embodiments, methods of the disclosure further comprise removing particulates from the process gas. In certain embodiments, methods of the disclosure do not comprise contacting the process gas with a gas separation system (e.g., Amine Absorption, Adsorption (PSA, TSA, or VSA), Cryogenics, or Membranes).

[0103] In certain embodiments, the membrane is a bipolar membrane. In further embodiments, the bipolar membrane comprises an anion exchange layer and a cation exchange layer. In yet further embodiments, the bipolar membrane is configured to operate in forward bias. In other embodiments, the bipolar membrane is configured to operate in reverse bias. In certain embodiments, wherein the method further comprises producing H+ions and OH“ ions within the bipolar membrane, and wherein the bipolar membrane is configured to allow the H+ions to flow to the cathode chamber and the OH" ions to flow to the anode chamber. . In other embodiments, the method further comprises producing OH“, HCOa-, or COa2-, or a combination thereof, at the cathode, and producing H+at the anode, and the bipolar membrane is configured to allow the OH“, HCOa-, CO32-ions to flow from the cathode chamber and the H+ions to flow from the anode chamber.

[0104] In certain embodiments, methods of the disclosure do not comprise reducing carbon dioxide to carbon monoxide at the anode.

[0105] In certain embodiments, the anode does not comprise gold.

[0106] In certain embodiments, methods of the disclosure do not comprise concentrating carbon dioxide in the process gas.

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[0108] In certain embodiments, methods of the disclosure do not comprise concentrating carbon dioxide in the humidified process gas.

[0109] In certain embodiments, the process gas comprises from about 1 wt% to about 100 wt% carbon dioxide. In further embodiments, the process gas comprises from about 1 wt% to about 40 wt% carbon dioxide. In yet further embodiments, the process gas comprises from about 40 wt% to about 90 wt% carbon dioxide. In still further embodiments, the process gas comprises from about 90 wt% to about 100 wt% carbon dioxide. In certain embodiments, the process gas comprises about 1 wt% carbon dioxide. In further embodiments, the process gas comprises about 5 wt% carbon dioxide. In yet further embodiments, the process gas comprises about 10 wt% carbon dioxide. In still further embodiments, the process gas comprises about 15 wt% carbon dioxide. In certain embodiments, the process gas comprises about 20 wt% carbon dioxide. In further embodiments, the process gas comprises about 25 wt% carbon dioxide. In yet further embodiments, the process gas comprises about 30 wt% carbon dioxide. In still further embodiments, the process gas comprises about 35 wt% carbon dioxide. In certain embodiments, the process gas comprises about 40 wt% carbon dioxide. In further embodiments, the process gas comprises about 45 wt% carbon dioxide. In yet further embodiments, the process gas comprises about 50 wt% carbon dioxide. In still further embodiments, the process gas comprises about 55 wt% carbon dioxide. In certain embodiments, the process gas comprises about 60 wt% carbon dioxide. In further embodiments, the process gas comprises about 65 wt% carbon dioxide. In yet further embodiments, the process gas comprises about 70 wt% carbon dioxide. In still further embodiments, the process gas comprises about 75 wt% carbon dioxide. In certain embodiments, the process gas comprises about 80 wt% carbon dioxide. In further embodiments, the process gas comprises about 85 wt% carbon dioxide. In yet further embodiments, the process gas comprises about 90 wt% carbon dioxide. In still further embodiments, the process gas comprises about 95 wt% carbon dioxide. In certain embodiments, the process gas comprises or about 100 wt% carbon dioxide.

[0110] In certain embodiments, the process gas comprises from about 5 parts per thousand to about 500 parts per thousand carbon dioxide. In further embodiments, the process gas comprises from about 5 parts per thousand to about 50 parts per thousand carbon dioxide. In yet further embodiments, the process gas comprises from about 50 parts per thousand to about 100 parts per thousand carbon dioxide. In still further embodiments, the process gas comprises from about 100 parts per thousand to about 150 parts per thousand carbon dioxide. In certain embodiments, the process gas comprises from about 150 parts per thousand to about 200 parts - 11 - FH13150382.3 Attorney Docket No.: HCV-00125

[0111] per thousand carbon dioxide. In further embodiments, the process gas comprises from about 200 parts per thousand to about 250 parts per thousand carbon dioxide. In yet further embodiments, the process gas comprises from about 250 parts per thousand to about 300 parts per thousand carbon dioxide. In still further embodiments, the process gas comprises from about 300 parts per thousand to about 350 parts per thousand carbon dioxide. In certain embodiments, the process gas comprises from about 350 parts per thousand to about 400 parts per thousand carbon dioxide. In further embodiments, the process gas comprises from about 400 parts per thousand to about 450 parts per thousand carbon dioxide. In yet further embodiments, the process gas comprises from about 450 parts per thousand to about 500 parts per thousand carbon dioxide.

[0112] In certain embodiments, methods of the disclosure result in essentially no carbon dioxide emissions.

[0113] In certain embodiments, the anode chamber further comprises an anolyte inlet and an anolyte outlet.

[0114] In certain embodiments, the reduction reactor and electrolyzer are configured according to Fig. 1.

[0115] In certain embodiments, the reduction reactor and electrolyzer are configured according to Fig. 2.

[0116] In certain embodiments, the electrolyzer is configured according to Fig. 3.

[0117] In certain embodiments, the electrolyzer is configured according to Fig. 4.

[0118] In certain embodiments, provided herein is an iron composition, prepared according to a method of the present disclosure.

[0119] Systems for Producing Iron Compositions

[0120] In the present disclosure, certain components of these systems are described as being “coupled” to one another. As will be appreciated, the term “coupled” as used herein describes components that are operationally linked to one another, but does not preclude the presence of intervening components between those said to be coupled to one another. Additionally, as will be appreciated, various system components are described as “having” certain features. Such descriptions do not preclude, and specifically contemplate, the presence of additional features, such as inlets, outlets, valves, control mechanisms, measurement devices, heating and / or cooling systems, etc. Additionally, in the systems of the present disclosure, certain components are described as having one or more outlets or inlets. Such outlets and inlets may represent separate structural elements, or may be combined into a single inlet or outlet as suitable. The - 12 - FH13150382.3 Attorney Docket No.: HCV-00125

[0121] person of ordinary skill in the art will recognize that, once the critical features and operating conditions of systems such as those described herein are understood, the detailed design and operation of such systems involved many choices, such as specific reagent flows, separation steps, etc. While the present disclosure provides a number of specific embodiments, any suitable combination of these design choices may be made.

[0122] In certain aspects, provided herein are systems for producing an iron composition comprising:

[0123] a reduction reactor comprising:

[0124] a first process gas outlet;

[0125] a first reducing gas inlet;

[0126] an iron oxide source inlet;

[0127] an iron product outlet;

[0128] an electrolyzer comprising:

[0129] an anode chamber comprising

[0130] an anode;

[0131] a cathode chamber comprising;

[0132] a cathode;

[0133] a first process gas inlet coupled to the first process gas outlet of the reduction reactor;

[0134] a first reducing gas outlet optionally coupled to the first reducing gas inlet of the reduction reactor;

[0135] a membrane disposed between and configured to separate the anode chamber from the cathode chamber;

[0136] wherein the anode chamber and the cathode chamber are in ionic communication; and optionally, wherein the first reducing gas outlet of the electrolyzer is coupled to the first reducing gas inlet of the reduction reactor.

[0137] In certain embodiments, the cathode is configured to convert carbon dioxide to carbon monoxide and hydrogen.

[0138] In certain embodiments, the first reducing gas outlet of the electrolyzer is coupled to the first reducing gas inlet of the reduction reactor.

[0139] In certain embodiments, systems of the present disclosure further comprise a heater configured to heat gaseous fluids, comprising:

[0140] a second reducing gas inlet coupled to the first reducing gas outlet of the electrolyzer;

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[0142] a second reducing gas outlet coupled to the first reducing gas inlet of the reduction reactor.

[0143] In certain embodiments, the heat exchanger further comprises:

[0144] a third reducing gas inlet coupled to the first reducing gas outlet of the cathode chamber; and

[0145] a third reducing gas outlet coupled to the reducing gas inlet of the reduction reactor. In certain embodiments, the heat exchanger is configured to both cool gaseous fluids and heat gaseous fluids, independently, such that the heat exchanger cools a first gaseous fluid and heats a second gaseous fluid.

[0146] In certain embodiments, systems of the disclosure further comprise a humidifier, configured to introduce water (e.g., as water vapor) into a gaseous stream, wherein the humidifier comprises:

[0147] a third process gas inlet coupled to the first process gas outlet of the reduction reactor; and

[0148] a humidified process gas outlet coupled to the first process gas inlet of the electrolyzer. In certain embodiments, the anode chamber further comprises an anolyte inlet and an anolyte outlet. In further embodiments, the anolyte outlet further comprises an anodic gas outlet. In certain embodiments, the anode chamber further comprises an anodic gas outlet. In further embodiments, the anodic gas outlet is coupled to an oxygen inlet of the reduction reactor.

[0149] In certain embodiments, the anode does not comprise gold. In some embodiments, the cathode does not comprise gold.

[0150] In certain embodiments, the iron composition comprises iron and carbon.

[0151] In certain embodiments, the reduction reactor comprises a Smelting Reduction Furnace, Direct Reduction of Iron (DRI) reactor, shaft furnace, blast furnace, or rotary kiln. In some embodiments, the reduction reactor comprises a tube furnace. In further embodiments, the reduction reactor is configured to produce hot-briquetted iron (HBI).

[0152] In certain embodiments, the system is configured according to Fig. 1.

[0153] In certain embodiments, the system is configured according to Fig. 2.

[0154] In certain embodiments, the electrolyzer is configured according to Fig. 3.

[0155] In certain embodiments, the electrolyzer is configured according to Fig. 4.

[0156] In certain embodiments, provided herein are iron compositions, prepared according to a system of the present disclosure.

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[0158] In certain embodiments, the membrane is a bipolar membrane. In further embodiments, the bipolar membrane comprises an anion exchange layer and a cation exchange layer. In yet further embodiments, the bipolar membrane is configured to operate in forward bias. In other embodiments, the bipolar membrane is configured to operate in reverse bias. In certain embodiments, wherein the method further comprises producing H+ions and OH“ ions within the bipolar membrane, and wherein the bipolar membrane is configured to allow the H+ions to flow to the cathode chamber and the OH" ions to flow to the anode chamber. In other embodiments, the method further comprises producing OH“, HCO-, or CO2-, or a combination thereof, at the cathode, and producing H+at the anode, and the bipolar membrane is configured to allow the OH“, HCOa-, COa2-ions to flow from the cathode chamber and the H+ions to flow from the anode chamber.

[0159] Unless otherwise defined herein, scientific and technical terms used in this application shall have the meanings that are commonly understood by those of ordinary skill in the art. Generally, nomenclature used in connection with, and techniques of, chemistry described herein, are those well-known and commonly used in the art.

[0160] The methods and techniques of the present disclosure are generally performed, unless otherwise indicated, according to conventional methods well known in the art and as described in various general and more specific references that are cited and discussed throughout this specification.

[0161] Chemistry terms used herein, unless otherwise defined herein, are used according to conventional usage in the art, as exemplified by “The McGraw-Hill Dictionary of Chemical Terms”, Parker S., Ed., McGraw-Hill, San Francisco, C.A. (1985).

[0162] All of the above, and any other publications, patents and published patent applications referred to in this application are specifically incorporated by reference herein. In case of conflict, the present specification, including its specific definitions, will control.

[0163] When the amount of an impurity is specified at a level of "about" a value (e.g., “about 0,” “about 45%, ” or “about 1300 nm”), it is understood by those of skill in the art that such a measurement is accurate to a certain number of significant figures based on the relevant detection method used.

[0164] The term “ionic communication” as used herein refers to the ability for ions to freely flow between two objects or regions of an object, e.g., between the cathodic chamber and anodic chamber of an electrochemical cell, in accordance with local chemical gradients. Non- - 15 - FH13150382.3 Attorney Docket No.: HCV-00125

[0165] limiting examples of such gradients include flow of ions from an area of high electrical potential to low electrical potential, from high ion concentration to low ion concentration, and from high chemical potential to low chemical potential. As will be understood by one of ordinary skill in the art, two objects or regions may be physically separated by a semi-permeable barrier (e.g., not in fluid communication) but still be in ionic communication, e.g., by virtue of ion diffusion or transport through the barrier.

[0166] EXAMPLES

[0167] The invention now being generally described, it will be more readily understood by reference to the following examples which are included merely for purposes of illustration of certain aspects and embodiments of the present invention, and are not intended to limit the invention.

[0168] Example 1: Operational Procedure for an Exemplary Iron-Producing System

[0169] In-laboratory testing of an exemplary electrochemical reduction-gas looping system of the disclosure is centered around a CO2 electrolyzer, connected to a heated reduction furnace (e.g., tube furnace), as shown in Fig. 2. Initially, the system is charged with either providing a reducing gas (a CO & H2-rich gas blend) to the furnace or providing CO2 to the electrolyzer. A gas flow pump, positioned generally immediately before or after the electrolyzer to operate on cooler gas, is used to circulate the reducing / efprocessnt gas through the system at 40-200 seem, controlled by a mass flow controller. 1000+ seem are sometimes used for higher volume tests. Humidified CO2 and H2O-rich gas is flowed through the cathodic side of a bipolar or anion-exchange membrane electrolyzer with a 25-100 cm2active area and is subsequently reduced to a CO- and H2-rich reducing gas. This reducing gas is optionally pre-heated and injected into a tube furnace (e.g., Lindberg / Blue M tube furnace) operating at 750-1250 °C. Inside the quartz tube, a sample boat is charged with iron ore (e.g., concentrate, fines, or pellets). As hot efprocessnt gas exits the system, it is cooled via a heat exchanger and humified by passing it through an aqueous bubbler before reinjection into the electrolyzer. Optionally, the system can also be mildly pressurized (< 3 bar) during the initial charging phase using a pressure regulator. Circulated gas is sampled at intervals for analysis via gas chromatograph to assess operating conditions, and the iron product is analyzed post-reduction through a variety of characterization methods including powder x-ray diffraction, XRF, XPS, and SEM.

[0170] - 16 - FH13150382.3 Attorney Docket No.: HCV-00125

[0171]

[0172] FIG. 3 shows the assembly of the electrochemical cell. The electrochemical cell comprises a titanium anode current collector, a stainless steel 904L cathode current collector, separated by an ion-exchange membrane (e.g., anion-exchange membrane, cation-exchange membrane, or bipolar membrane) and two PTFE gaskets. The anode and cathode flow fields are serpentine channels within a 5 cm2 geometric area. The electrochemical cell was assembled by fixing the anode (2) to the anode current collector (1) with a PTFE gasket (3). The ion-exchange membrane (4) was placed on top of the PTFE gasket followed by another PTFE gasket (5) to sandwich the membrane into place. The cathode (6) was then placed on top of the PTFE gasket followed by the cathode current collector (7). The assembled cell was then pressed together by tightening 8 bolts around the perimeter of the cell. Tubing (1 / 8” OD PTFE) was connected to the compression fittings of the anode current collector to cycle anolyte from the anolyte reservoir into the cell (8). A peristaltic pump is used to circulate an electrolyte, often 10 mM KHCO3 aqueous solution, from an anolyte reservoir into the anode chamber at flowrate of 3 mL / min. Similarly, tubing (1 / 8” OD PTFE) was connected to the compression fittings of the cathode current collector to feed gaseous CO2 into the cell (9). The gaseous CO2 or mixed CO2-rich gas from a cylinder is humidified with water using a bubbler and then fed to the cathode chamber at a flow rate of 30 seem. The efprocessnt gas was directly fed into an in-line gas chromatography (GC). An auto-sampled gas flow was first sent onto a 6’ Hayesep-D pre-column, and then flowed onto a 3’ MS-5A column, while back-flushing the pre-column before CO2 elutes. At the same time, another sample was collected and held without flowing. After H2 eluted from the MS-5A column, the held sample was released and injected into an 18’ Hayesep-D column. CO was quantified after being eluted from the Hayesep-D column. The electrochemical measurements were performed on either a Gamry Ref 600 potentiostat / galvanostat (Gamry Instruments Inc, USA) an Admiral Prime Squidstat Plus potentiostat / galvanostat (Admiral Instruments, USA), or a direct current power supply. FIG. 4 shows the full electrochemical system configuration for the small-scale demonstrations. Electrochemical reactions were generally performed at 2.8-3.2 V for at least 50 hours. GC and potentiostat data were used to inform performance characterizations including Faradaic efficiency, single-pass conversion, energy efficiency, catalyst activity & stability, and current density.

[0173] FIGs. 1 and 2 show demonstrations of lab-scale integration of the electrochemical cell with an exemplary DRI reactor.

[0174] - 17 - FH13150382.3 Attorney Docket No.: HCV-00125

[0175] INCORPORATION BY REFERENCE

[0176] All publications and patents mentioned herein are hereby incorporated by reference in their entirety as if each individual publication or patent was specifically and individually indicated to be incorporated by reference. In case of conflict, the present application, including any definitions herein, will control.

[0177] EQUIVALENTS

[0178] While specific embodiments of the subject invention have been discussed, the above specification is illustrative and not restrictive. Many variations of the invention will become apparent to those skilled in the art upon review of this specification and the claims below. The full scope of the invention should be determined by reference to the claims, along with their full scope of equivalents, and the specification, along with such variations.

[0179] - 18 - FH13150382.3

Claims

Attorney Docket No.: HCV-00125CLAIMSWe claim:

1. A method for producing an iron composition, the method comprising:reacting a source of iron oxide with a reducing gas feed comprising carbon monoxide and hydrogen in a reduction reactor to produce the iron product and a process gas comprising carbon dioxide and water;optionally, combining the process gas with water to produce a humidified process gas; contacting the process gas or the humidified process gas with a cathode of an electrolyzer while applying a voltage across the cathode and the anode, wherein the electrolyzer comprises:an anode chamber comprising an anode;a cathode chamber comprising the cathode; anda membrane separator disposed between and configured to separate the anode chamber from the cathode chamber;wherein the anode chamber and the cathode chamber are in ionic communication;thereby producing carbon monoxide and hydrogen; andoptionally, transferring the carbon monoxide and hydrogen to the reduction reactor.

2. The method of claim 1, comprising combining the process gas with water to produce a humidified process gas.

3. The method of claim 2, further comprising contacting the humidified process gas with the cathode of the electrolyzer.

4. The method of any one of claims 1-3, further comprising collecting the carbon monoxide and hydrogen.

5. The method of any one of claims 1-4, comprising transferring the carbon monoxide and hydrogen to the reduction reactor.

6. The method of claim 5, wherein transferring the reducing gas to the reduction reactor further comprises pre-heating the reducing gas.- 19 - FH13150382.3Attorney Docket No.: HCV-001257. The method of claim 5 or 6, wherein transferring the reducing gas to the reduction reactor further comprises combining the reducing gas with a carrier gas (e.g., air, He, N2, or Ar).

8. The method of any one of claims 1-7, wherein the iron composition comprises iron and carbon.

9. The method of any one of claims 1-8, wherein the reduction reactor is a Smelting Reduction Furnace, Direct Reduction of Iron (DRI) reactor, shaft furnace, blast furnace, or rotary kiln.

10. The method of claim 9, wherein the reduction reactor is configured to produce hot-briquetted iron (HBI).

11. The method of any one of claims 1-10, further comprising flowing a cooling fluid through the reduction reactor.

12. The method of any one of claims 1-11, wherein the source of iron oxide is an iron ore, optionally wherein the iron ore is in a form of lumps, pellets, or particles (e.g., fines).

13. The method of any one of claims 1-12, further comprising producing oxygen at the anode.

14. The method of claim 13, further comprising collecting the oxygen from the anode chamber.

15. The method of claim 13 or 14, further comprising transferring the oxygen from the anode chamber to the reduction reactor.

16. The method of claim 13 or 14, further comprising transferring the oxygen from the anode chamber to a furnace, e.g., an electric arc furnace or basic oxygen furnace.

17. The method of any one of claims 1-16, wherein the reduction reactor comprises a tube furnace.

18. The method of any one of claims 1-17, further comprising flowing a carrier gas through the reduction reactor.- 20 - FH13150382.3Attorney Docket No.: HCV-0012519. The method of any one of claims 1-18, further comprising passing the process gas or the humified process gas through a heat exchanger prior to contacting the process gas or humidified process gas with the cathode.

20. A method for the reduction of carbon dioxide comprising:optionally, combining process gas comprising carbon dioxide with water to produce a humidified process gas;contacting the process gas or the humidified process gas with a cathode of an electrolyzer while applying a voltage across the cathode and the anode, wherein the electrolyzer comprises:an anode chamber comprising an anode;a cathode chamber comprising a cathode; anda membrane separator disposed between and configured to separate the anode chamber from the cathode chamber;and wherein the anode chamber and the cathode chamber are in ionic communication; thereby producing a reducing gas comprising carbon monoxide and hydrogen.

21. The method of any one of claims 1-20, further comprising contacting an aqueous electrolyte solution with the anode.

22. The method of claim 20 or 21, further comprising producing oxygen at the anode.

23. The method of claim 22, further comprising collecting the oxygen from the anode chamber.

24. The method of any one of claims 1-23, wherein all of the hydrogen in the reducing gas is produced within the cathode chamber of the electrolyzer.

25. The method of any one of claims 1-24, wherein carbon monoxide and hydrogen are produced at the cathode.

26. The method of any one of claims 1-25, wherein carbon monoxide and hydrogen are both produced at the same cathode.

27. The method of any one of claims 1-26, wherein the cathode is configured to simultaneously produce carbon monoxide and hydrogen.- 21 - FH13150382.3Attorney Docket No.: HCV-0012528. The method of any one of claims 1-27, wherein carbon monoxide and hydrogen are both produced in the same electrolyzer.

29. The method of any one of claims 1-28, wherein carbon monoxide and hydrogen are both produced at the same cathode.

30. The method of any one of claims 1-29, wherein carbon monoxide and hydrogen are simultaneously produced at the same cathode.

31. The method of any one of claims 1-30, wherein the reducing gas is substantially free of hydrocarbons.

32. The method of any one of claims 1-31, wherein the method does not comprise producing hydrocarbons at the cathode.

33. The method of any one of claims 1-32, wherein the process gas further comprises at least one gas selected from H2, CO, N2, CH4, and a combination thereof.

34. The method of any one of claims 1-33, wherein the method further comprises removing nitrogen oxides and sulfur oxides from the process gas.

35. The method of any one of claims 1-34, wherein the method does not comprise contacting the process gas with a gas separation system (e.g., Amine Absorption, Adsorption (PSA, TSA, or VSA), Cryogenics, or Membranes).

36. The method of any one of claims 1-35, further comprising removing particulates from the process gas.

37. The method of any one of claims 1-36, wherein the membrane is an anion exchange membrane.

38. The method of any one of claims 1-36, wherein the membrane is a bipolar membrane, which comprises an anion exchange layer and a cation exchange layer.

39. The method of claim 38, wherein the bipolar membrane is configured to operate in forward bias.

40. The method of claim 38, wherein the bipolar membrane is configured to operate in reverse bias.- 22 - FH13150382.3Attorney Docket No.: HCV-0012541. The method of any one of claims 38-40, wherein the method further comprises producing H+ions and OH“ ions within the bipolar membrane, and wherein the bipolar membrane is configured to allow the H+ions to flow to the cathode chamber and the OH" ions to flow to the anode chamber.

42. The method of any one of claims 38-41, wherein the method further comprises producing OH“, HCO-, or CO2-, or a combination thereof, at the cathode, and producing H+at the anode, and the bipolar membrane is configured to allow the OH“, HCOa-, COa2-ions to flow from the cathode chamber and the H+ions to flow from the anode chamber.

43. The method of any one of claims 1-42, wherein the method does not comprise reducing carbon dioxide to carbon monoxide at the anode.

44. The method of any one of claims 1-43, wherein the anode does not comprise gold.

45. The method of any one of claims 1-44, wherein the method does not comprise concentrating carbon dioxide in the process gas.

46. The method of any one of claims 1-45, wherein the method does not comprise concentrating carbon dioxide in the humidified process gas.

47. The method of any one of claims 1-46, wherein the process gas comprises from about 1 wt% to about 40 wt% carbon dioxide.

48. The method of any one of claims 1-47, wherein the process gas comprises from about 40 wt% to about 90 wt% carbon dioxide.

49. The method of any one of claims 1-48, wherein the process gas comprises from about 90 wt% to about 100 wt% carbon dioxide.

50. The method of any one of claims 1-49, wherein the process gas comprises from about 5 parts per thousand to about 500 parts per thousand carbon dioxide.

51. The method of any one of claims 1-50, wherein the method results in essentially no carbon dioxide emissions.

52. The method of any one of claims 1-51, wherein the anode chamber further comprises an anolyte inlet and an anolyte outlet.- 23 - FH13150382.3Attorney Docket No.: HCV-0012553. The method of any one of claims 1-52, wherein the electrolyzer is configured according to Fig. 3.

54. The method of any one of claims 1-53, wherein the electrolyzer is configured according to Fig. 4.

55. An iron composition prepared using the method of any one of claims 1-19.

56. A system for producing an iron composition comprising:a reduction reactor comprising:a first process gas outlet;a first reducing gas inlet;an iron oxide source inlet;an iron product outlet;an electrolyzer comprising:an anode chamber comprisingan anode;a cathode chamber comprising;a cathode;a first process gas inlet coupled to the first process gas outlet of the reduction reactor;a first reducing gas outlet optionally coupled to the first reducing gas inlet of the reduction reactor;a membrane disposed between and configured to separate the anode chamber from the cathode chamber;wherein the anode chamber and the cathode chamber are in ionic communication; and optionally, wherein the first reducing gas outlet of the electrolyzer is coupled to the first reducing gas inlet of the reduction reactor.

57. The system of claim 56, wherein the cathode is configured to convert carbon dioxide to carbon monoxide and hydrogen.

58. The system of claim 56 or 57, wherein the first reducing gas outlet of the electrolyzer is coupled to the first reducing gas inlet of the reduction reactor.- 24 - FH13150382.3Attorney Docket No.: HCV-0012559. The system of claim 56 or 58, wherein the system further comprises a heater configured to heat gaseous fluids, comprising:a second reducing gas inlet coupled to the first reducing gas outlet of the electrolyzer;a second reducing gas outlet coupled to the first reducing gas inlet of the reduction reactor.

60. The system of any one of claims 56-59, wherein the system further comprises a heat exchanger, comprising:a second process gas inlet coupled to the first process gas outlet of the reduction reactor; anda second process gas outlet coupled to the first process gas inlet of the electrolyzer.

61. The system of claim 60, wherein the heat exchanger further comprises:a third reducing gas inlet coupled to the first reducing gas outlet of the cathode chamber; anda third reducing gas outlet coupled to the reducing gas inlet of the reduction reactor.

62. The system of claim 59 or 61, wherein the heat exchanger is configured to both cool gaseous fluids and heat gaseous fluids, independently, such that the heat exchanger cools a first gaseous fluid and heats a second gaseous fluid.

63. The system of any one of claims 56-62, wherein the system comprises a humidifier, configured to introduce water (e.g., as water vapor) into a gaseous stream, wherein the humidifier comprises:a third process gas inlet coupled to the first process gas outlet of the reduction reactor;anda humidified process gas outlet coupled to the first process gas inlet of the electrolyzer.

64. The system of any one of claims 56-63, wherein the anode chamber further comprises an anolyte inlet and an anolyte outlet.

65. The system of claim 61, wherein the anolyte outlet further comprises an anodic gas outlet.

66. The system of any one of claims 56-65, wherein the anode chamber further comprises an anodic gas outlet.- 25 - FH13150382.3Attorney Docket No.: HCV-0012567. The system of any one of claims 56-66, wherein the anodic gas outlet is coupled to an oxygen inlet of the reduction reactor.

68. The system of any one of claims 56-67, wherein the anode does not comprise gold.

69. The system of any one of claims 56-68, wherein the cathode does not comprise gold.

70. The system of any one of claims 56-69, wherein the iron composition comprises iron and carbon.

71. The system of any one of claims 56-70, wherein the reduction reactor is a Smelting Reduction Furnace, Direct Reduction of Iron (DRI) reactor, shaft furnace, blast furnace, or rotary kiln.

72. The system of claim 71, wherein the reduction reactor is configured to produce hot-briquetted iron (HBI).

73. A system according to Fig. 1.

74. A system according to Fig. 2.

75. An iron composition prepared using the system of any one of claims 56-74.- 26 - FH13150382.3

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