Electrochemical cogeneration of iron and commodity chemicals

Abstract

An electrochemical reactor comprising a source of a magnetic field positioned in proximity to a cathode and configured to generate a magnetic field; and an electrochemical cell comprising an anode and the cathode, and further comprising a catholyte channel configured to direct a catholyte stream comprising an iron-containing feedstock to the cathode; an anolyte channel configured to direct an anolyte stream comprising a metal chloride to the anode, wherein the catholyte channel and the anolyte channel are disposed between the cathode and the anode; and a separator disposed between the catholyte channel and the anolyte channel, wherein the electrochemical reactor is configured to electrochemically oxidize chloride anions to chlorine gas at a surface of the anode, and wherein the electrochemical reactor is further configured to electrochemically reduce the iron-containing feedstock to an iron particle comprising iron metal at the surface of the cathode and in the magnetic field.

What is claimed is: 
     
         1 . An electrochemical reactor, comprising:
 a source of a magnetic field positioned in proximity to a cathode and configured to generate a magnetic field at a surface of the cathode; and   an electrochemical cell comprising an anode and the cathode,   wherein the electrochemical cell further comprises:
 a catholyte channel configured to direct a catholyte stream comprising an iron-containing feedstock to the cathode; 
 an anolyte channel configured to direct an anolyte stream comprising a metal chloride to the anode, wherein the catholyte channel and the anolyte channel are disposed between the cathode and the anode; and 
 a separator disposed between the catholyte channel and the anolyte channel, 
   wherein the electrochemical reactor is configured to electrochemically oxidize chloride anions to chlorine gas at a surface of the anode, and   wherein the electrochemical reactor is further configured to electrochemically reduce the iron-containing feedstock to an iron particle comprising iron metal at the surface of the cathode and in the magnetic field.   
     
     
         2 . The electrochemical reactor of  claim 1 , wherein the electrochemical reactor is configured to electrochemically reduce the iron-containing feedstock to the iron particle at a current efficiency ratio of at least 0.75, wherein the current efficiency ratio is a ratio of charge used for the reduction of the iron-containing feedstock to a total charge provided to the cathode. 
     
     
         3 . The electrochemical reactor of  claim 1 , wherein the iron particle comprises an iron metal powder. 
     
     
         4 . The electrochemical reactor of  claim 1 , wherein the iron-containing feedstock comprises hematite, maghemite, magnetite, goethite, limonite, pyrite, red mud, or a combination thereof; preferably magnetite or hematite. 
     
     
         5 . The electrochemical reactor of  claim 1 , wherein the catholyte stream comprises from 0.1 to 30 weight percent of the iron-containing feedstock, preferably 0.1 to 15 weight percent of the iron-containing feedstock, more preferably 0.1 to 5 weight percent of the iron-containing feedstock, each based on a total weight of the catholyte stream. 
     
     
         6 . The electrochemical reactor of  claim 1 , wherein the catholyte stream further comprises an aqueous solution comprising a metal hydroxide, wherein the metal hydroxide comprises an alkali metal hydroxide, an alkaline earth metal hydroxide, or a combination thereof. 
     
     
         7 . The electrochemical reactor of  claim 6 , wherein the metal of the metal hydroxide is derived from the metal of the metal chloride of the anolyte stream. 
     
     
         8 . The electrochemical reactor of  claim 6 , wherein the metal hydroxide is present in the aqueous solution in an amount from 20 to 50 weight percent, preferably from 25 to 45 weight percent, based on a total weight of the catholyte stream. 
     
     
         9 . The electrochemical reactor of  claim 1 , wherein
 the anolyte stream comprises an aqueous solution comprising the metal chloride, and   wherein the metal chloride comprises an alkali metal chloride, an alkaline earth metal chloride, or a combination thereof.   
     
     
         10 . The electrochemical reactor of  claim 8 , wherein the anolyte stream has a pH of less than 7, preferably from 0 to 5. 
     
     
         11 . The electrochemical reactor of  claim 9 , wherein the metal chloride is present in the aqueous solution in an amount from 1 to 60 weight percent, preferably 5 to 50 weight percent, more preferably 10 to 40 weight percent, based on a total weight of the anolyte stream. 
     
     
         12 . The electrochemical reactor of  claim 1 , wherein the anolyte stream further comprises an acid having a pKa of 2 or less. 
     
     
         13 . The electrochemical reactor of  claim 1 , wherein the separator comprises an anion exchange membrane, a cation exchange membrane, an anion selective membrane, a cation selective membrane, a zwitterionic membrane, a nanoporous membrane, a polybenzimidazole-containing membrane, a polysulfone-containing membrane, a polycarboxylic-containing membrane, a polyetherketone-containing membrane, a membrane comprising a polymer of intrinsic microporosity, or a combination thereof,
 preferably wherein the separator is a cation selective membrane.   
     
     
         14 . The electrochemical reactor of  claim 1 , wherein the separator comprises a cation-selective membrane that is permeable to an alkali metal cation, an alkaline earth metal cation, or a combination thereof. 
     
     
         15 . The electrochemical reactor of  claim 1 , wherein the cathode comprises aluminum, carbon, molybdenum, copper, nickel, titanium, iron, chromium, an alloy thereof, or a combination thereof, preferably carbon, nickel, iron, chromium, an alloy thereof, or a combination thereof. 
     
     
         16 . The electrochemical reactor of  claim 1 , wherein the anode comprises carbon, titanium, lead, nickel, iron, platinum, iridium, ruthenium, tantalum, niobium, zirconium, vanadium, hafnium, aluminum, tin, cobalt, antimony, tungsten, copper, an alloy thereof, an oxide thereof, or a combination thereof. 
     
     
         17 . The electrochemical reactor of  claim 1 , further comprising a gas separation unit in fluid communication with the anolyte channel, wherein the gas separation unit is configured to separate at least a portion of the chlorine gas from the anolyte stream. 
     
     
         18 . The electrochemical reactor of any of  claim 1 , further comprising an iron metal separation unit in fluid communication with the catholyte channel, wherein the iron metal separation unit is configured to separate the iron particle from the catholyte stream. 
     
     
         19 . The electrochemical reactor of  claim 1 , wherein the electrochemical reactor is configured to operate at a temperature of 50° C. to 140° C., preferably 70° C. to 110° C., more preferably 85° C. to 110° C. 
     
     
         20 . The electrochemical reactor of  claim 1 , further comprising a voltage source electrically connected to the anode and the cathode, wherein the voltage source is configured to apply a voltage to the electrochemical cell to provide the chlorine gas and the iron particle. 
     
     
         21 . The electrochemical reactor of  claim 1 , wherein the source of the magnetic field comprises a permanent magnet, an electromagnet, an electropermanent magnet, or a combination thereof. 
     
     
         22 . The electrochemical reactor of  claim 1 , wherein the source of the magnetic field is positioned in proximity to the cathode and configured to provide a magnetic field at the surface of the cathode that is at least 0.025 Tesla, preferably 0.05 to 10 Tesla, more preferably 0.05 to 1 Tesla. 
     
     
         23 . The electrochemical reactor of  claim 1 , wherein the source of the magnetic field is configured to provide a modulated magnetic field. 
     
     
         24 . The electrochemical reactor of  claim 1 , wherein
 the source of the magnetic field comprises an electromagnet, and   the electromagnet is positioned adjacent to the cathode and opposite to the catholyte stream.   
     
     
         25 . The electrochemical reactor of  claim 1 , further comprising an additional source of a magnetic field positioned in proximity to the anode, wherein the electrochemical cell is disposed between the source and the additional source, and
 wherein the electrochemical reactor is configured to electrochemically reduce at least a portion of the iron-containing feedstock to the iron particle at the surface of the cathode in a magnetic field provided by the source and the additional source.   
     
     
         26 . The electrochemical reactor of  claim 25 , wherein the additional source is a field generating device or a field propagating device. 
     
     
         27 . The electrochemical reactor of  claim 25 , wherein the additional source comprises a permanent magnet, an electromagnet, an electropermanent magnet, or a combination thereof. 
     
     
         28 . The electrochemical reactor of  claim 1 , wherein the source of a magnetic field and the additional source of a magnetic field are arranged in a Helmholtz configuration or an anti-Helmholtz configuration. 
     
     
         29 . The electrochemical reactor of  claim 1 , wherein the electrochemical cell is a plurality of electrochemical cells, preferably comprising 2 to 500 electrochemical cells, more preferably 5 to 200 electrochemical cells, or 50 to 170 electrochemical cells. 
     
     
         30 . The electrochemical reactor of any of  claim 1 , wherein the electrochemical cell is a plurality of electrochemical cells between the source and an additional source of a magnetic field. 
     
     
         31 . The electrochemical reactor of  claim 1 , wherein:
 the iron-containing feedstock has an average particle size of less than 20 micrometers, preferably 1 to 10 micrometers, and the iron particle has an average particle size of 50 to 1000 micrometers, preferably 50 to 200 micrometers;   the iron-containing feedstock has an average particle size of 20 micrometers or greater, preferably 20 to 50 micrometers, and the iron particle has an average particle size of 50 to 1000 micrometers, preferably 50 to 200 micrometers;   the iron particle has a morphology of a spheroid, a flake, a sheet, a platelet, a needle, or a combination thereof, preferably wherein the iron particle is in the form of a flowable powder or slurry;   the iron-containing feedstock has a morphology of spheroid, a flake, a sheet, a platelet, or a combination thereof, preferably wherein the iron containing feedstock is in the form of a flowable powder or slurry;   the iron particle has an average maximum dimension of between 0.1 and 1,000 micrometers, or has an aspect ratio of 1 to 100, preferably 1 to 20;   the iron-containing feedstock has an average maximum dimension between 5 and 500 micrometers, preferably 10 to 50 micrometers, or has an aspect ratio of 1 to 100, preferably 1 to 20;   the iron particle has a specific total embedded emissions of less than 0.8 tons of CO 2  per ton of the iron metal, when determined according to the European Union simplified bubble approach method for determining specific embedded emissions under the Carbon Border Adjustment Mechanism;   the iron particle has a carbon emission intensity of less than 1100 kilograms of CO 2  per ton of the iron metal, when determined according to ISO 14404;   the iron particle has a carbon emission intensity of less than 900 kilograms of CO 2  per ton of the iron metal, when determined according to the Intergovernmental Panel on Climate Change Methodology 2006 Guidelines for National Greenhouse Gas Inventories;   the iron particle has a carbon emission intensity of less than 1500 kilograms of CO 2  per ton of the iron metal, when determined according to the 2017 World Steel Life Cycle Inventory Methodology;   the iron particle has a carbon emission intensity of less than 1300 kilograms of CO 2  per ton of the iron metal, when determined according to the 2008 World Resource Institute Iron and Steel Greenhouse Gas Protocol;   the iron particle has a carbon emission intensity of less than 800 kilograms of CO 2  per ton of the iron metal, when determined according to the Commission Implementing Regulation (EU) 2018/2066;   the iron particle has a specific total embedded emissions of less than 0 tons of CO 2  per ton of the iron metal, when determined according to the European Union simplified bubble approach method for determining specific embedded emissions under the Carbon Border Adjustment Mechanism; or   a combination thereof.   
     
     
         32 . A method of operating the electrochemical reactor of  claim 1 , the method comprising:
 flowing the catholyte stream through the catholyte channel;   flowing the anolyte stream through the anolyte channel;   applying the magnetic field at the surface of the cathode;   applying a voltage between the cathode and the anode to:
 (i) electrochemically reduce the at least a portion of the iron-containing feedstock to produce the iron particle at the surface of the cathode while the magnetic field is applied at the cathode; and 
 (ii) electrochemically oxidize at least a portion of the chloride anions to produce the chlorine gas at the surface of the anode; and 
   contacting a cation of the metal chloride and a hydroxide anion to form a metal hydroxide in the catholyte stream to operate the electrochemical reactor.   
     
     
         33 . The method of  claim 32 , further comprising contacting the surface of the cathode with the catholyte stream to remove the iron particle from the cathode. 
     
     
         34 . The method of  claim 32 , further comprising:
 directing the catholyte stream to an iron separation unit fluidly connected to a downstream side of the catholyte channel;   separating at least a portion of the iron particle from the catholyte stream to provide a separated catholyte stream; and   returning the separated catholyte stream to an upstream side of the catholyte channel.   
     
     
         35 . The method of  claim 32 , further comprising:
 directing the anolyte stream to a liquid/gas separation unit fluidly connected to a downstream side of the anolyte channel;   separating the chlorine gas from the anolyte stream to form a separated anolyte stream; and   returning the separated anolyte stream to an upstream side of the anolyte channel.   
     
     
         36 . The method of  claim 32 , further comprising
 reducing the voltage to stop the electrochemical reduction of the iron-containing feedstock,   decreasing or removing the magnetic field at the cathode, and   contacting the surface of the cathode with the catholyte stream to flush the iron particle from the cathode.   
     
     
         37 . The method of  claim 32 , further comprising treating the iron-containing feedstock prior to entering the catholyte stream to decrease a particle size of the iron-containing feedstock, to decrease an impurity amount of the iron-containing feedstock, or a combination thereof, preferably wherein the treating comprises physical grinding, selective separation by particle size or density, flotation, leaching with caustic solution, leaching with acidic solution, or a combination thereof. 
     
     
         38 . The method of  claim 37 , wherein the treating comprises physical grinding, selective separation by particle size or density, flotation, leaching with caustic solution, leaching with acidic solution, or a combination thereof. 
     
     
         39 . The method of  claim 32 , further comprising purification of the catholyte through selective precipitation or removal of dissolved impurities liberated from the iron-containing feedstock.