US20150083606A1 - Molten Carboxylate Electrolytes for Electrochemical Decarboxylation Processes - Google Patents

Molten Carboxylate Electrolytes for Electrochemical Decarboxylation Processes Download PDF

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US20150083606A1
US20150083606A1 US14/495,642 US201414495642A US2015083606A1 US 20150083606 A1 US20150083606 A1 US 20150083606A1 US 201414495642 A US201414495642 A US 201414495642A US 2015083606 A1 US2015083606 A1 US 2015083606A1
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electrolyte
cell
salt
molten salt
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James Mosby
Sai Bhavaraju
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Enlighten Innovations Inc
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Ceramatec Inc
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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B3/00—Electrolytic production of organic compounds
    • C25B3/20—Processes
    • C25B3/29—Coupling reactions
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B3/00—Electrolytic production of organic compounds
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B3/00—Electrolytic production of organic compounds
    • C25B3/20—Processes
    • C25B3/23—Oxidation
    • C25B9/08—
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B9/00—Cells or assemblies of cells; Constructional parts of cells; Assemblies of constructional parts, e.g. electrode-diaphragm assemblies; Process-related cell features
    • C25B9/17—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B9/00—Cells or assemblies of cells; Constructional parts of cells; Assemblies of constructional parts, e.g. electrode-diaphragm assemblies; Process-related cell features
    • C25B9/17—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof
    • C25B9/19—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof with diaphragms
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • electrochemical decarboxylation is performed in polar organic solvents.
  • polar organic solvents have limitations on their concurrent use as electrolytes, such as limited solubility for carboxylic acids, limited conductivity, and low oxidation potential.
  • the low oxidation potential causes the electrolyte to be oxidized congruently with the carboxylic acid generating additional activated species at the anode surface which increases the number of undesirable or inefficient side products.
  • limitations inhibit the commercial application of electrochemical decarboxylation processes because of inadequate current efficiency and low product selectivity. This is especially true for electrolytes based on methanol which is one of the most commonly used electrolytes for electrochemical decarboxylation.
  • an electrochemical cell having an electrolyte compartment with a quantity of electrolyte, the electrolyte comprising a quantity of an inorganic salt of a carboxylic acid dissolved in a molten salt electrolyte; an anode in communication with the electrolyte; a cathode in communication with the electrolyte; and a voltage source that decarboxylates the metal salt of the carboxylic acid into radicals that react to form at least one radical coupling product.
  • an electrochemical cell having an anolyte compartment housing an anolyte comprising a inorganic salt of a carboxylic acid dissolved in a molten salt electrolyte; an anode in communication with the anolyte; a catholyte compartment capable of housing a quantity of catholyte; a cathode in communication with the catholyte; a membrane separating the anolyte and catholyte compartments; and a voltage source.
  • the cation of the electrolyte inorganic salt is selected from an alkaline metal, an alkaline earth metal and mixtures of the same. In some embodiments, the cation of the electrolyte inorganic salt is selected from lithium, sodium, potassium, magnesium, calcium, and mixtures of the same. In some embodiments, the electrolyte contains a mixture of inorganic cations. In some embodiments, the electrolyte contains a mixture of at least three inorganic cations. In some embodiments, the oxidation potential of an anion in the molten electrolyte is higher than the oxidation potential of the carboxylate anion.
  • a carboxylate portion of the inorganic carboxylate salt is selected from: acetate, propionate, lactate, butyrate, pentanoate, hexanoate, heptanoate, octanoate, laurate, oleate, stearate, linoleate, palmitate, myristrate, levulinate, valerate, benzoate, naphthenate and naphthoate.
  • the electrolyte is a eutectic mixture with a lower melting point than the melting point of the individual components of the electrolyte mixture.
  • the cell is operated at a temperature above the melting point of the molten salt electrolyte, but below the melting point of the products of the reduction and oxidation reactions.
  • a method for producing a coupled radical product having the steps of providing a inorganic salt of a carboxylic acid; contacting the salt of a carboxylic acid with a molten salt electrolyte applying a voltage to the electrolyte and carboxylate salt.
  • the electrolyte is a eutectic mixture with a lower melting point than the melting point of the individual components of the electrolyte mixture.
  • FIG. 1 shows a schematic drawing of an electrochemical cell that may be used for carrying out electrochemical decarboxylation process using molten salt electrolytes in some embodiments.
  • FIG. 2 shows a schematic drawing of an electrochemical cell that may also be used for carrying out the electrochemical decarboxylation process using molten salt electrolytes in some embodiments.
  • FIG. 3 is a plot of the cell potential and current density of the electrochemical decarboxylation of sodium lactate using a sodium lactate molten salt electrolyte.
  • FIG. 4 shows a gas chromatogram of the products obtained from the electrochemical decarboxylation of sodium lactate in sodium lactate molten salt electrolyte with an inset showing the mass spectrum of the main product obtained which matches acetaldehyde.
  • the present disclosure describes the use of molten salts as electrolytes for electrochemical decarboxylation processes (EDP).
  • EDP electrochemical decarboxylation processes
  • the EDP can be used to convert a variety of carboxylic acids into different hydrocarbon products.
  • Carboxylic acids (RCO 2 H) make up a board class of organic compounds, where R can be an alkyl group, cycloalkyl group, an alkyenyl, and alkynyl group and an aryl group.
  • the R group can also contain a hydrocarbon that may possess heteroatoms such as O, S, N, etc.
  • the electrolyte disclosed herein can be used for electrochemical decarboxylation which removes CO 2 from the carboxylic acid and creates a high energy radical or a carbocation to form carbon-carbon, carbon-hydrogen, or carbon-oxygen bonds with other species present in solution.
  • This process can be used to synthesize a variety of different types of organic compounds such as saturated hydrocarbons, diols, esters, olefins, aryl-alkyl compounds, etc.
  • the electrochemical decarboxylation process is advantageous to other methods conventionally used to synthesize these compounds because the chemicals involved in the process are environmentally friendly, and the process does not require the use of catalyst.
  • the reactive carboxylic acid may be of formulas R 1 COOM and R 2 COOM.
  • the resulting products obtained by practicing the electrolytic decarboxylation disclosed process are compounds of formula R 1 —R 2 .
  • Each of R 1 and R 2 is independently selected from unsubstituted and substituted alkyl, unsubstituted and substituted cycloalkyl, unsubstituted and substituted heterocyclyl, substituted and unsubstituted alkenyl, substituted and unsubstituted alkynyl, substituted and unsubstituted aryl, and substituted and unsubstituted heteroaryl.
  • Each M is independently an inorganic cation selected from alkaline and alkaline earth metals and ammonium.
  • Substitutions on substituted alkyl, cycloalkyl, heterocyclyl, alkenyl, alkynyl, aryl, and heteroaryl include: halogen, unsubstituted C 1-8 alkyl, —CN, —NO 2 , ⁇ O, —C(O)R A , —CO 2 R A , —C(O)NR A R B , —OR A , —OC(O)R A , —OC(O)NR A R B , —NR C C(O)R A , —NR C C(O)NR A R B , —NR A R B , —NR C CO 2 R A , —NR C S(O) 2 R A , —SR A , —S(O)R A , —S(O) 2 R A , —S(O) 2 NR A R B ; wherein each of R A , R B , and R C , when present, is independently selected from
  • substitutions on substituted alkyl, cycloalkyl, heterocyclyl, alkenyl, alkynyl, aryl, and heteroaryl are located geminal to the group —COOM.
  • molten salt electrolytes provide high conductivity, high solubility and reaction compatibility all of which promote high yield and efficiency.
  • Other properties of molten salts which are added benefits to their use as electrolytes are low surface tension, viscosity, and vapor pressure. Molten salts are fluid above their melting point, or sometimes when used as mixtures are fluid below their individual melting point due to the formation of an eutectic system or mixture.
  • the molten salt electrolytes are made with a salt or a mixture of salts with a single elemental cation and anion, for example the electroplating of magnesium is performed using an electrolyte comprising of the mixture NaCl—CaCl 2 —KCl—MgCl 2 .
  • the molten salt electrolytes of the present disclosure include salts with polyatomic ions or a mixture of salts including polyatomic ions.
  • One class of polyatomic ion based molten salts that have been used for electrolytes for different electrochemical process are ionic liquids.
  • Ionic liquids are comprised of a single bulky polyatomic cation and anion pair which melts around or below 100° C.
  • the molten salt electrolytes disclosed in the present disclosure are not limited to polyatomic ions, or to a single cation and anion pair, or to temperatures below 100° C.
  • One example of using molten salts containing atomic and polyatomic ions is the use of sodium carboxylates from fatty acids as a molten solvent for the Henkel disproportionation reaction disclosed in PCT/US2000/021648. Unlike this in the present disclosure, the molten salts are chosen specifically for the use as electrolytes in an electrolytic cell to perform electrochemical decarboxylation.
  • Such an electrolyte system improves the electrochemical decarboxylation process by providing the inherent benefits of molten salt electrolytes, while the use of complex polyatomic ions increases the amount of active species present in the electrolyte and at the electrode surface increasing the selectivity and hence yield of the process.
  • the present disclosure includes novel electrolyte systems designed for the electrochemical decarboxylation process and include at least one cation and anion pair making up a molten salt.
  • the cation and anion of the molten salt are chosen such that the carboxylic acid being decarboxylated has a high solubility, the oxidation of the anion does not increase the amount of side products, and the product of the decarboxylation is easily separated from the molten salt.
  • the molten salt electrolyte is also tuned for high electrochemical stability in the required potential range, and low chemical reactivity to species generated by the decarboxylation process.
  • Such a molten salt electrolyte increases the selectivity of the decarboxylation process by reducing the number of reactions which can occur in proximity to the anode, which increases the yield and the Coulombic efficiency. Also, being able to operate at high temperatures reduces the activation energy required to cause the oxidation of the carboxylate to the radical, in-turn lowering the operating potential of the cell and reducing the electrical energy required for the conversion.
  • the ability to combine different cations and anions provides tunability of the electrolyte so that it can be optimized for the specific decarboxylation of interest.
  • the electrochemical decarboxylation is a technique used to generate radicals for synthetic applications and is characterized as either Kolbe electrolysis or non-Kolbe electrolysis.
  • Kolbe electrolysis is used to define the decarboxylation of carboxylic acids leading to radicals that then combine forming either homocoupling or heterocoupling products, and can also add to double bonds.
  • a generic example of decarboxylation leading to homocoupling is shown below.
  • non-Kolbe electrolysis is used to define the decarboxylation of carboxylic acids that lead to the formation of carbocations from a two electron oxidation.
  • the carbon cation can then participate in a number of electrophilic reactions such as home-type reactions, substitution and addition reactions, and heteroatom bond formation.
  • Olefins are one of the possible products that can be obtained from a two electron oxidation of a carboxylic acid.
  • a generic example of decarboxylation leading to an electrophilic substitution reaction is shown below.
  • the decarboxylation is performed on salts of carboxylic acids.
  • the saponification of carboxylic acids follows the generally accepted procedure of reacting the carboxylic acid with a base (BOH) at an elevated temperature.
  • bases are lithium hydroxide, sodium hydroxide, potassium hydroxide, ammonium hydroxide and phosphonium hydroxide.
  • a generic neutralization reaction is written below.
  • the decarboxylation of the carboxylate salts follow the same general reaction schemes as was shown for the carboxylic acids, except instead of a proton being generated another cation B + is generated which can then be involved in reduction reactions at the cathode.
  • the decarboxylation of the salts is performed using a two compartment electrochemical cell, which is afforded via an ion exchange or an ion selective membrane, and the cation or proton produced at the anode can be shuttled from the anolyte to the catholyte.
  • Carboxylic acids are becoming a popular substrate to perform the synthesis of industrially important compounds as they are economically and environmentally friendly.
  • One application for which they may be considered, is as alternatives to organohalides in the Heck reaction for the formation of carbon-carbon double bonds.
  • Replacing the organohalides with carboxylic acids is more environmentally friendly, because CO 2 and H 2 are the only by-products formed instead of the halide by-products produced using the other routes. They may also be considered as substrates for cross-coupling reactions where the carboxylic acid can act as either the nucleophilic or electrophilic coupling partner. This is advantageous as there are a large number of carboxylic acids available commercially, which are more economical than the conventionally used organohalides and/or organometallic reagents.
  • molten salt means a liquid that is made up of different cation and anion pairs.
  • eutectic means a mixture of chemicals or elements with a composition which solidifies at a lower temperature than any other composition of the mixture.
  • hydrocarbon means a compound consisting of carbon and hydrogen and can refer to saturated or unsaturated compounds.
  • efficiency and “current efficiency” are used interchangeably and refer to the Coulombic efficiency of the electrochemical decarboxylation process.
  • conversion means the amount of reactant that is consumed in the electrochemical decarboxylation process.
  • the term “selectivity” is used to describe the amount of the consumed reactant that is converted into the product of interest, and the term “yield” means the amount of the original reactant that is converted into the product of interest.
  • carboxylic acid is a compound with the general formula RCO 2 H, where the “R” can represent saturated or unsaturated hydrocarbon chains.
  • decarboxylation herein refers to the process of removing CO 2 from a compound, specifically from a carboxylic acid or anion.
  • substituteduent and “functional group” are used interchangeably and herein refer to an atom or group of atoms that has substituted a hydrogen atom on a carbon chain of a hydrocarbon.
  • the present disclosure is generally directed to a method using molten salts as electrolytes in electrochemical decarboxylation processes (EDP).
  • EDP electrochemical decarboxylation processes
  • the molten salt electrolyte will be chosen based on the specific type of carboxylic acid precursor being decarboxylated in the electrolytic cell, and the hydrocarbon product that is produced.
  • the ability to use different molten salts for different reactions provides a means to increase the reaction yield and improve the product isolation for a variety of different systems.
  • Some of the properties that will affect the choice of the molten salt are melting point, hydrophilicity/lipophilicity, electrochemical stability, and miscibility.
  • An example of changing the molten salt cation for different synthesis requirements is the need to use an X + cation based salt instead of a Y + , or a mixture of salts with X + and Y + cations in order to decrease the melting point of the molten salt electrolyte, and/or to use a two compartment cell with the compartments separated by a ion selective membrane.
  • the choice of anion is known to affect the solubility, miscibility and oxidative stability of the molten salt.
  • an A ⁇ anion could be used where the A ⁇ is a carboxylate anion and is directly used in the decarboxylation process, or a mixture of A ⁇ and C ⁇ anions could be used where C ⁇ is an inactive anion at the electrode and increases the conductivity of the molten salt.
  • the cation of the molten salt electrolyte is an inorganic cation.
  • the inorganic cation is an alkaline metal.
  • the inorganic cation is an alkaline earth metal.
  • the inorganic cation is selected from alkaline and alkaline earth metals.
  • the inorganic cation is ammonium.
  • the inorganic cation is selected from alkaline and alkaline earth metals and ammonium.
  • the inorganic cation is selected from alkaline metals and ammonium.
  • the inorganic cation is selected from alkaline earth metals and ammonium.
  • the cation of the molten salt electrolyte is based on or more of the following cations listed as non-liming examples: ammonium, sodium, lithium, potassium, magnesium, and calcium.
  • the cation is selected from one or more of the cations: imidazolium, pyridinium, pyrrolidinium and phosphonium. Each of these cations can be used as the sole cation of the molten salt or used as one component of a mixture of cations in the molten salt.
  • the cation of the molten salt electrolyte should be chosen so it is either inactive in the electrochemical window that the cell is operated in, is transported through an ion exchange or ion selective membrane or it should be chosen to have a low reduction potential.
  • the later choice would be for cases where the cation is reduced at the cathode at a low reduction potential, while the electrolysis of interest occurs at the anode.
  • the low potential reduction at the cathode will help reduce the overall cell potential and thus lower the energy demand and improves the economics of the electrolysis.
  • the cation of the molten salt is a polyatomic ion.
  • the use of polyatomic cations can drastically lower the melting points of the molten salt when compared to the corresponding alkali or alkaline metal cations.
  • lithium chloride melts at 605° C. sodium chloride melts at 801° C.
  • ammonium chloride melts at 340° C. and tetrabutylammonium chloride melts at 105° C.
  • the melting point of the molten salt with a polyatomic cation can be low enough, less than 100° C., to be included in a special class of molten salts termed ionic liquids.
  • the reduction of the polyatomic cation at the cathode provides a low potential reduction couple for the oxidation occurring at the anode.
  • a two compartment cell is used and another species provides a low potential reduction reaction.
  • the cation of the molten salt is an alkali or alkaline metal cation.
  • the use of an alkali or alkaline metal cation provides a highly conductive and stable electrolyte.
  • the small size and relativity high charge density on the alkali and alkaline cations relative to the polyatomic cations increases the conductivity of molten salts with small cations.
  • Molten salts comprising of alkali and alkaline cations can be used in single or two compartment cells as inert charge carriers or as the active species involved with the electron transfer at the cathode.
  • the molten salt electrolyte is comprised of a mixture of cations.
  • a mixture of salts that have different cations but the same anion can have a melting point that is suppressed compared to the melting points of the individual salts of the mixture.
  • the ability to decrease the melting point by adding different cations without adding different anions to the molten salt is important because the additional cations are not involved in the reactions at the anode surface and thus do not contribute to the formation of side products produced during the oxidation.
  • the different cations making up a molten salt electrolyte can be atomic or polyatomic and can have the same or different amount of charge.
  • the anion of the molten salt may be selected from the groups of halides, sulphonates, amides, tosylates, aluminates, borates, sulfates, nitrates, and carboxylates.
  • the anions of the molten salt should be electrochemical inactive and chemically inert to reactions that could occur at the surface at the anode; or the anions should consist of anions that are involved in the decarboxylation process.
  • the molten salt is comprised of a mixture of anions.
  • the different anions in the molten salt can have the same or different charge number, and can increase conductivity and decrease the melting point of the molten salt.
  • the anions of the molten salt will be chosen so that they are similar to the carboxylate being processed in the electrolytic cell.
  • the similarity of the anion of the molten salt electrolyte and the carboxylate being decarboxylated increases the solubility of the later.
  • one of the differences between the carboxylate used in the molten salt and the carboxylate being processed will be that the oxidation potential of the former is larger, thus promoting the oxidation of the later forming the desired hydrocarbon.
  • the anion of the molten salt will be the same as the carboxylate that is being processed in the electrolytic cell.
  • any oxidation of the molten salt electrolyte will form the same product as the oxidation of the carboxylate being processed in the cell. It should be clear to one experienced in the field that the anion of the molten salt electrolyte should be chosen to primary reduce the side reactions at the anode, and then other properties that the anion affects can be taken into consideration.
  • the molten salt electrolyte is comprised of a mixture of salts that have different cations but the same anion. In another embodiment, the molten salt electrolyte is comprised of a mixture of salts that have the same cation and different anions. In another embodiment, the molten salt electrolyte is comprised of a mixture of salts with different cations and different anions.
  • the composition of the molten salt mixture will be determined by: 1) the melting point of the melt and the desired operating temperature, 2) the conductivity of the molten salt, 3) reactions that occur at the anode, and 4) reactions occurring at the cathode or membrane interface.
  • the molten salt electrolyte will be comprised of at least one salt for which the anion is comprised of the carboxylate being converted by the decarboxylation process. It should be clarified that the carboxylic acid or salt of the carboxylic acid being decarboxylated can be added to a molten salt electrolyte to a small or large extent anywhere from 1-100% by weight.
  • the molten salt is made up of a binary mixture, in other cases it is made up of a ternary mixture, still yet in other cases it is made up of a quaternary mixture.
  • the molten salt can be comprised of a mixture with any number of salts required to obtain the properties required.
  • the molten salt electrolyte is prepared by heating a pure salt until it melts.
  • multiple salts are mechanically mixed together and then the mixture is heated up to afford the molten salt.
  • one salt or a mixture of salts is heated and additional salts are added to the melt.
  • the salt mixture is heated and cooled several times before being used as an electrolyte. This promotes intimate mixing of the different salts present in the mixture helping to disrupt any short range order and thus suppresses the melting point.
  • the composition of the molten salt is optimized in order to decrease the temperature which the mixture freezes.
  • the composition of the mixture is optimized by varying the concentration of the different salt components, while monitoring the physical properties of the mixture.
  • the composition of the molten salt electrolyte can contain at low as 2% of any particular salt and up to 98% of any other particular salt.
  • the optimized composition of the molten salt electrolyte could be one that causes a eutectic to form.
  • the majority of the molten salt is a carboxylate salt. In another embodiment, the majority of the molten salt is a salt other than a carboxylate salt.
  • the carboxylate salt or carboxylic acid that is of interest to the decarboxylation process can make up a small or large portion of the molten salt composition, and can be added to the molten salt as the electrolysis progresses.
  • carboxylate anions that could be used as components in the molten salt electrolytes are acetate, propionate, lactate, butyrate, pentanoate, hexanoate, heptanoate, octanoate, laurate, oleate, stearate, linoleate, palmitate, myristrate, levulinate, valerate, benzoate, naphthenate and naphthoate.
  • the molten salt electrolyte is used in a one compartment cell and a carboxylic acid or a salt of a carboxylic acid is dissolved into the molten salt electrolyte.
  • the molten salt electrolyte needs to be designed to limit the number of side reactions at the anode, have a high conductivity, and provide a low potential reduction reaction at the cathode.
  • the first requirement is in order to increase the current efficiency and product selectivity and depends on the anions present in the molten salt electrolyte.
  • the second requirement is required to decrease the operating potential of the cell and depends on both the cation and anions in the mixture.
  • the third requirement is also desired to lower the cell's operating potential and is dependent on the cations in the mixture.
  • the products of the reduction and oxidation reaction should be easily separated from the molten salt upon formation and easily separated from each other.
  • the products formed are gases at the operating temperature of the cell and thus are easily separated from the molten salt electrolyte, for example through the application of a slight vacuum.
  • a two compartment electrolytic cell schematically represented in FIG. 1 or FIG. 2 which have two compartments separated by an ion exchange ( 5 ) or an ion selective membrane, for example a NaSelect® membrane.
  • the anolyte and the catholyte can both be comprised of a molten salt electrolyte, each designed specifically for the reactions that occur at the two different electrodes, or each being the same electrolyte with different and/or the same species dissolved in them.
  • the anolyte can be comprised of a molten salt electrolyte
  • the catholyte can be comprised of an electrolyte that is not a molten salt. It should be clear to those skilled in the art, that in this case the catholyte can be designed to produce a second chemical or chemicals of value while the conversion of the carboxylate to a hydrocarbon is occurring at the anode.
  • the anolyte is fed into the anode chamber ( 7 ), and during electrolysis is oxidized at the anode's (2) surface causing the decarboxylation of the carboxyl functional group forming a radical and CO 2 .
  • the reduction of the catholyte is occurring and to maintain charge balance a positive ion must transfer from the anode to the cathode, and in the case when the anolyte and catholyte are separated there needs to be a path for the positive ions to transfer between compartments.
  • an ion conducting membrane ( 5 ) selectively transfers alkali ions (M + ), including but not limited to the ions of, sodium, lithium, and potassium, from the anolyte to the catholyte under the influence of an applied electrical field.
  • an ion exchange membrane ( 5 ) shuttles the cations from the anolyte to the catholyte.
  • an anion exchange membrane ( 5 ) can be used to shuttle anions from the catholyte to the anolyte which are then decarboxylated at the anode.
  • a three compartment cell can be used which uses more than one type of membrane.
  • the membrane ( 5 ) is between 10 and 5000 microns thick, or more preferable the membrane is between 100 and 1000 microns thick, or even more preferable the membrane is between 200 and 700 microns thick.
  • the membrane is in the form of disk with diameters between 0.25-25 cm, even more preferably the diameter is between 1.27-12.7 cm, or most preferably between 2.54-7.62 cm and are assembled in a scaffold.
  • the membrane is in the form of a cylinder with a diameter between 0.25-25 cm, even more preferably between 1.27-12.7 cm, or most preferably between 2.54-7.62 cm.
  • the electrochemical cell can be in a parallel plate configuration which uses flat membranes, for example as shown in FIG. 1 and FIG. 2 .
  • the electrochemical cell is in a tubular configuration which uses tubular electrodes and membranes.
  • the anode ( 2 ) can comprise any suitable material that allows oxidation reactions to occur in the anolyte compartment ( 7 ) when an electrical field is applied between the anode ( 2 ) and cathode ( 1 ).
  • anode materials include, but are not limited to, platinum, titanium, nickel, cobalt, iron, stainless steel, lead dioxide, metal alloys, combination thereof, and other known or novel anode materials.
  • the anode ( 2 ) may comprise of iron-nickel alloys such as KOVAR® or INVAR®.
  • the anode may comprise carbon based electrodes such as boron doped diamond, glassy carbon, and synthetic carbon.
  • the anode comprises a dimensionally stable anode (DSA), which may include, but is not limited to, rhenium dioxide and tantalum pentoxide on a titanium substrate.
  • DSA dimensionally stable anode
  • the cathode ( 1 ) may also be fabricated of any suitable cathode material that allows the reduction reaction to occur without electrode corrosion.
  • the cathode may comprise of the materials used for the anode ( 2 ) or the cathode ( 1 ) may comprise of materials different from that used as the anode.
  • suitable cathode materials include without limitation, platinum, nickel, stainless steel, graphite, and any other suitable cathode material that is known or novel.
  • the electrodes have a smooth morphology such as a foil or thin film.
  • the anode ( 2 ) and cathode ( 1 ) have a high surface area morphology, for example but not limited to, a foam, grit, or other porous structure.
  • the anode ( 2 ) and cathode ( 1 ) have the same morphology.
  • the electrodes have a different morphology.
  • the electrodes are attached to the membrane in the cell.
  • the electrolyte is fed into the cell without a membrane.
  • the electrolyte comprises of a molten salt electrolyte and a carboxylic acid or a salt of a carboxylic acid.
  • the anolyte is fed into the anolyte compartment ( 7 ), and the catholyte is fed into the catholyte compartment ( 3 ) which are separated by a membrane ( 5 ).
  • the anolyte consists of a molten salt electrolyte for which the composition includes at least one salt of a carboxylic acid.
  • the carboxylate that is dissolved into the molten salt electrolyte is chosen based on the desired products of the decarboxylation reaction, and can be aliphatic or aromatic in nature.
  • the carboxylate ion can contain various functional groups, and or heteroatoms.
  • multiple carboxylates are dissolved in the molten salt electrolyte and decarboxylated in the electrolysis cell simultaneously, thus leading to homo and hetero coupling.
  • the anolyte solution may comprise of a mixture of the molten salt electrolyte and a polar solvent.
  • suitable polar solvents include without limitation, water, methanol, ethanol, isopropanol, n-propanol, acetone, acetonitrile, dioxane, butanol, dimethyl sulfoxide (DMSO), carbon disulfide (CS2), diethyl carbonate, ethylene carbonate, and glycerol.
  • the anolyte solution may comprise of a mixture of a molten salt electrolyte and an aromatic solvent.
  • the anolyte solution may comprise of a mixture of a molten salt electrolyte and a non-polar organic solvent.
  • non-polar organic solvents are hexane, cyclohexane, pentadecane, petroleum ethers, and dodecane.
  • the carboxylate salts are soluble in the molten salt electrolyte, and the products of the decarboxylation are soluble in the non-polar solvent, and thus are easily separated from the reactants.
  • Certain alkali ion conductive membranes for example NaSICON and LiSICON-type membranes, have a high temperature tolerance and thus the anolyte solution may be heated to a higher temperature without substantially affecting the temperature of the catholyte solution or the functionality of the membrane.
  • the anolyte is a molten salt at temperatures above 150° C.
  • the catholyte is a polar solvent which could boil at the temperature of the molten salt, thus requiring a membrane with a high temperature tolerance.
  • molten sodium and/or lithium metal is used as the catholyte as some NaSICON and LiSICON-type membranes are stable to molten sodium and/or lithium metal.
  • the anolyte solution may optionally contain a supporting electrolyte which is soluble in the molten salt and provides additional electrolyte conductivity in the molten salt.
  • supporting electrolytes include alkali metal hydroxide, alkali metal salts, ammonium tetrafluoroborate, tetramethylammonium hexafluorophosphate, tetrabutylammonium tetrafluorobotate, tetramethylammonium perchlorate, and tetraethylammonium perchlorate. It should be appreciable to those skilled in the art that other soluble ionic compounds may be used.
  • the catholyte may comprise of a solvent that is the same or different than the molten salt anolyte. This is afforded because the ion conducting membrane ( 5 ) isolates the compartments from each other.
  • the anolyte and catholyte may be separately selected specifically for the reactions that occur in each compartment and/or the solubility of the chemicals required for the specific reactions. This permits one to design an inexpensive catholyte which may have different properties than the anolyte, for example to have high ionic conductivity and a low reduction potential.
  • the catholyte is comprised of an unsaturated aqueous solution containing alkali salt or ammonium salts.
  • the salt concentration is between 0.1-50% by weight, or more preferably between 5-25% by weight, or most preferably between 7-15% by weight.
  • the catholyte is an unsaturated high boiling point polar organic solvent with an alkali salt or ammonium salt.
  • the catholyte is a molten salt that is compatible with the ion that is transferring across the membrane and provides a low potential reduction reaction.
  • catholyte is a liquid metal such as sodium or lithium metal. In all the embodiments described above, one can imagine that the catholyte is chosen such that the reduction reaction produces chemical/chemicals that are economically valuable.
  • the cathode ( 1 ) When an electric field is applied between the cathode ( 1 ) and anode ( 2 ), a reduction reaction occurs at the cathode ( 1 ).
  • the catholyte solution is an aqueous based solution, water is reduced to hydrogen gas and hydroxide ions.
  • the hydroxide formed can then combine with the cation that is transported through the membrane ( 5 ) causing the hydroxide concentration of the catholyte to increase as the electrolysis is performed.
  • the catholyte is comprised of an ammonium solution the ammonium is reduced producing ammonia and hydrogen, which depending on the cell temperature will separate from the catholyte as gases.
  • the catholyte is a metal the alkali ion that is transported through the membrane is reduced to the metal.
  • the oxidation of a carboxylic acid or a carboxylate anion leads to decarboxylation, producing carbon dioxide and a radical.
  • the radical can then combine with another radical to form homo- or hetero-coupling products, following Kolbe electrolysis or it can react with other species present at the electrode's surface following non-Kolbe electrolysis.
  • the decarboxylation leads to the formation of CO 2 and a carbon cation from a two electron oxidation. Following its formation, the carbon cation can then participate in nucleophilic reactions instead of coupling reactions.
  • the anolyte is used at temperatures above the melting point of the salt or the mixture of salts making up the molten electrolyte and above the boiling point of the product formed at the anode. In another embodiment, the anolyte is used at temperatures above the melting point of the salt or the mixture of salts making up the molten electrolyte, but below the boiling point or the melting point of the product.
  • the temperature of the anolyte will be chosen in a range according to the stability of the electrolyte and products. In one embodiment, the temperature of the anolyte is adjusted within this range to optimize the viscosity, conductivity, and product separation.
  • the temperature of the molten salt electrolyte promotes the decarboxylation through lowering the activation energy of the oxidation, and helping drive the CO2 from the carboxylate anion and electrolyte.
  • the potential the cell operates at is lowered because the amount of electrical energy required to cause the oxidation has decreased due to the system's thermal energy.
  • the electrolytic cell may be operated in a continuous mode. In continuous mode, the cell is initially filled with an anolyte and catholyte and then, during operation additional reactant is fed into the cell, and products, by-products, and/or diluted solutions are removed from the cell without ceasing operation of the cell.
  • the electrolytic cell is operated in batch mode. In batch mode, the anolyte and catholyte are fed initially into the cell, and then the cell is operated until a desired concentration of the product is produced. The cell is then emptied, and the products are collected. The cell is then refilled to start the process again. Also, in either mode, the feeding of the reactant may be done using a premade solution or using components that form the electrolyte in situ.
  • the anolyte comprises of a molten salt electrolyte, and a salt of a carboxylic acid.
  • carboxylic acid is dependent on the desired product and can be chosen from any class of carboxylic acids. Some non-limiting examples are fatty acids, alkyl carboxylic acids, amino acids, aryl carboxylic acids, and di- and tri-carboxylic acids.
  • the carboxylic acid can also have multiple substituents present, in addition to the carboxylic group. These additional functional groups can be located at any carbon site of the carboxylic acid, and in some embodiments are located in the alpha position to the carboxylate carbon. Both electron donating and withdrawing substituents can be present on the carboxylic acid.
  • Some non-limiting examples of electron donating substituents are hydroxyl, amine, amide, and ether groups. Some non-limiting examples of electron withdrawing substituents are halogens, nitriles, carbonyl, nitro, and nitride groups.
  • the functional group present in the alpha position to the carboxylate will help determine whether the decarboxylation will follow a one electron or two electron oxidation mechanism. In one embodiment, one electron oxidation will occur, favoring radical-radical coupling because there is no substituent present in the alpha position or the substituent is an electron withdrawing group. In another embodiment, the two electron oxidation is favored, because there is an electron donating group present in the alpha position to the carboxylate group.
  • the first step is to convert the carboxylic acid (RCO 2 H) into the corresponding alkali salt (RCO 2 B) via acid neutralization, where B is a base such as lithium, sodium, potassium, calcium, magnesium, phosphonium, or ammonium; RCO 2 H is a carboxylic acid and R is a hydrocarbon having a C 2 to C 22 hydrocarbon chain in which one of the hydrogen atoms can be substituted for different functional groups.
  • functional groups that can be present are hydroxyl, phenyl, esters, ethers, and ketones.
  • the carboxylic acid has other substituents which do not contain oxygen such as: halide, nitrile, amine, amide, and sulfide.
  • the carboxylic acid is obtained from biomass with the additional substituent already present.
  • the biomass derived carboxylic acid is first modified to include the additional functional groups.
  • the oxidation at the anode ( 2 ) causes the decarboxylation of the carboxylate anion, leading to the formation of carbon dioxide, and radicals of (R.) according to the reaction below:
  • the radical Once the radical is formed, it will react with other species at the electrode's surface, and if it reacts with another radical of the same carboxylate anion, it will form a homocoupling product as shown below:
  • This product can be in itself the chemical of interest, or it can be used as an intermediate precursor in the synthesis of the chemical of interest.
  • function groups on the carboxylic acid can be converted into double bonds and corresponding diene can be used as monomers for the production of elastic material.
  • the radical combines with a radical of a different carboxylate anion, then a heterocoupling product will be formed and an unsymmetrical compound will be obtained.
  • the heterocoupling product can be a chemical of interest or a precursor required to obtain a chemical of interest.
  • the decarboxylation will lead to a mixture of homocoupling and heterocoupling and thus provide a mixture of products. In one embodiment this mixture is commercially viable, yet in another embodiment the mixture will be further separated into a commercially viable product.
  • the molten salt electrolyte is designed to facilitate the separation of the products from the reactants.
  • the electrochemical cell is operated at a temperature that is above the product boiling point and the cell under slight vacuum.
  • the molten salt electrolyte can have high solubility of the polar carboxylate reactants, and poor solubility of the products, such that when a non-polar solvent is mixed with the molten salt electrolyte either before or after the electrolysis, the products partition to the non-polar solvent.
  • the separation is facilitated by designing a molten salt electrolyte that has a high freezing point, such that upon cooling the molten salt crystallizes and the products remain a liquid and are separated by a simple method such as filtration.
  • molten salt electrolyte over the conventional, polar organic electrolytes are: 1) the molten electrolyte is electrochemically stable and chemically inert, 2) the molten salt electrolyte has high conductivity, 3) the carboxylate species has a high conductivity in the molten salt electrolyte, 4) the molten salt electrolyte can be designed to permit easy separation of the product and the reactant, 5) the molten salt electrolyte is easily recycled and is an environmentally friendly solvent.
  • the examples disclosed herein used an experimental setup which is schematically shown in FIG. 1 or FIG. 2 .
  • the cell employed for these experiments minimized the distance between the electrodes and the membrane.
  • the membranes used in the examples consisted of 2.54 cm diameter NaSICON disks of about 1 mm thickness which were housed on scaffolds in the center of the cells. As the scaffold and membrane physically separate the anode and cathode compartments, there was a separate temperature controlled reservoir for the anolyte and catholyte. This allowed the chemistry and conditions of each electrolyte to be optimized for the respective electrode reactions.
  • the anolyte which contains the sodium salt of the carboxylic acid, is made by heating different salts together at different ratios. This was conducted by preparing the salts in a separate solution following conventional saponification reactions and then physically mixing the salt together. Or the salts were prepared in a single solution producing a homogenous mixture of the salts. For this method, a general saponification procedure was used during which the sodium carboxylate forms as the carboxylic acid is neutralized. The details of the molten salt preparation will be given as required in the following examples.
  • the catholyte can be made from any solution containing sodium salts, and for the examples given herein an aqueous sodium hydroxide solution was used. To obtain low solution resistance and minimize temperature difference across the membrane the temperatures of the catholyte was increased to 95° C.
  • a battery tester (Arbin BT2000) was connected and a current density between 10 and 100 mA/cm 2 was applied. During the electrolysis the voltage and current were monitored using MITS Pro battery testing software. The applied current density caused oxidation to occur at the anode (platinum mesh electrode) and reduction to occur at the cathode (nickel mesh electrode). As the battery tester transports electrons from the anode to the cathode, a charge balance must be maintained across the cell by the diffusion of positively charge ions. Given the high selectivity of the NaSICON membrane for Na-ions, it is the only species that can provide this balance, thus a high concentration of the sodium salt is desired.
  • the temperature of the cell during the experiments of the different molten salt electrolytes is higher than 150° C. some of the products and side products are gases and thus the experiments are conducted in a manner that permits the collection of the gas.
  • the gas from the reaction was passed through an aqueous solution of Ca(OH) 2 and then was collected in a gas bag. As the gas is passed through the Ca(OH) 2 the CO 2 that is produce from the decarboxylation at the anode is converted into CaCO 3 , and some of the products and side products condense allowing them to be collected and analyzed with GC-MS. The collected gas is also analyzed with GC and GC-MS.
  • an extraction procedure was used to analyze any products that were still mixed with the molten salt after the salt cooled to room temperature.
  • the molten salt electrolyte disclosed was used in an electrochemical decarboxylation process to convert the sodium salt of a carboxylic acid with a hydroxyl group into an aldehyde.
  • the aldehyde produced can be used as an intermediate to the production of other chemicals.
  • the molten salt electrolyte was comprised solely of the sodium salt of the carboxylic acid desired for the decarboxylation.
  • An aqueous solution containing 10% by weight sodium hydroxide was used as the catholyte (3) and the temperature was maintained between 80 and 100° C.
  • the molten sodium salt anolyte was prepared by evaporating the water off of an aqueous syrup of sodium lactate (Sigma, 60% DL) using slight vacuum and mild heat. The sodium lactate was then heated to and held at 150° C. for 48 h. The temperature of the sodium lactate was then heated to 160° C. and the cathode compartment ( 3 ) was inserted into the melted salt anolyte ( 7 ). The aqueous catholyte was heated on a stir plate to 95° C. and then was cycled through the cathode compartment of the cell ( 3 ) which was submersed into the anolyte ( 7 ). The cell was operated until enough charge passed to theoretically convert 10% of the sodium carboxylate electrolyte. During the electrolysis the temperatures of the anolyte was maintained at 160° C., and a current densities between 5 and 20 mA cm ⁇ 2 were employed.
  • FIG. 3 shows the current density ( 14 ) and cell potential ( 15 ) of the decarboxylation of sodium lactate in a sodium lactate electrolyte.
  • the response shows at a constant current the cell potential ( 15 ) varied greatly with time.
  • the large variance in cell potential is from the formation of CO 2 bubbles on the electrode and the release of these bubbles.
  • the reactions that occurred in the anode and cathode compartment are shown below.
  • the decarboxylation occurring in the anode compartment produced CO 2 which was bubbled through a calcium hydroxide solution forming calcium carbonate which was then analyzed using TGA.
  • the gas that passed through the calcium hydroxide solution was collected in a gas bag.
  • the GC-MS of the gas in the gas bag is shown in FIG. 4 .
  • the first peak shown in FIG. 4 was the elution of N 2 , O 2 , and CO 2 which was analyzed separately with a packed column and TCI detector.
  • the second peak shown in FIG. 4 was identified as acetaldehyde using the mass spectrum of the peak shown in the inset of the Figure.
  • the conditions used in this example promoted 2e ⁇ oxidation producing acetaldehyde following the reaction shown below.
  • the molten salt electrolyte with a different cation but the same anion used in Example 1 can be used in an electrochemical decarboxylation process to perform the decarboxylation of the lactate anion.
  • This example demonstrates how changing the cation of the molten salt electrolyte can lower the melting point of the molten salt and provide a low potential reduction reaction at the anode.
  • the molten salt electrolyte can be comprised solely of the ammonium salt of the carboxylic acid being processed by the decarboxylation process in a single compartment cell.
  • the molten sodium salt anolyte is prepared by evaporating the water off of an aqueous solution of ammonium lactate (Sigma, 60% DL) using slight vacuum and mild heat. The ammonium lactate is then heated to and maintained at temperature between 50 and 100° C. for the experiment. The cell is operated until enough charge passes to theoretically convert 10% of the sodium carboxylate in the electrolyte. A current density between 5 and 20 mA cm ⁇ 2 is employed during the electrolysis.
  • the decarboxylation occurring in the anode compartment will produce CO 2 which will be bubbled through a calcium hydroxide solution forming calcium carbonate which will be analyzed using TGA.
  • the gas that passes through the calcium hydroxide solution is collected in a gas bag, and analyzed using GC-MS.
  • the conditions described in this example will permit both 1e ⁇ and 2e ⁇ oxidation to occur producing acetaldehyde as shown in Example 1 and 2,3 butanediol following the reaction shown below.
  • the molten salt electrolyte disclosed can be used in an electrochemical decarboxylation process to convert the sodium salts of long chain carboxylic acids into long chain saturated hydrocarbons.
  • the saturated hydrocarbons produced can be further processed into either base lubricant or transportation fuel.
  • the molten salt electrolyte can be comprised of a mixture of sodium salts of carboxylic acids which mimic the feed stream of carboxylic acids obtain from biological sources.
  • the cell is run at temperatures above the boiling of aqueous sodium hydroxide, so a solution containing 10% by weight sodium hydroxide in ethyl glycol can be used as the catholyte.
  • the molten sodium salt anolyte can be prepared by mixing lauric, myristic, palmitic and stearic acid in methanol and then following standard saponification procedure, adding sodium hydroxide to the solution to crash out the sodium salts. Following the addition of the sodium hydroxide the methanol is removed with mild heat under vacuum. The dry sodium salts are then heated to 320° C. and held there for 48 h under nitrogen. The catholyte solution is heated to 150° C. in the cathode compartment of the cell. The cell is operated until enough charge passed to theoretically convert 10% of the sodium carboxylate electrolyte. During the electrolysis the temperature of the anolyte is maintained at 320° C., and a current density of 10 mA cm ⁇ 2 is employed.
  • the constant current density will produce a constant potential response in between 5 and 20 V.
  • the reactions that occur at the anode are shown below.
  • R is four different saturated hydrocarbons with carbon numbers of C 11 , C 13 , C 15 , and C 17 .
  • the decarboxylation occurring in the anode compartment produced CO 2 which is bubbled through a calcium hydroxide solution forming calcium carbonate which is then analyzed using TGA.
  • the gas that passes through the calcium hydroxide solution is collected in a gas bag to be analyzed using GC-MS.
  • the molten salt mixture is cooled to room temperature and dissolved in water.
  • the pH of the solution is adjust to 3 using acid, then liquid/liquid extraction is performed using hexane, and the hexane phase is analyzed with GC-MS.
  • an electrochemical cell comprises an electrolyte compartment capable of housing a quantity of electrolyte.
  • the electrolyte comprising a quantity of an alkali metal salt of a carboxylic acid dissolved in a molten salt electrolyte.
  • the alkali metal salt of the carboxylic acid may have at least one functional group in addition to the carboxylic acid moiety.
  • the electrochemical cell includes an anode and a cathode in communication with the electrolyte. It also includes a voltage source, wherein the voltage source decarboxylates the alkali metal salt of the carboxylic acid into alkyl radicals that react to form a coupled radical product.
  • the electrolyte may be a molten salt electrolyte where the cation of the electrolyte is chosen from lithium, sodium, potassium, magnesium, calcium and mixtures of the same.
  • the electrolyte may also be a molten salt selected from ammonium, imidazolium, pyridinium, pyrrolidinium and phosphonium.
  • the electrolyte may contain a mixture of the cations referenced above. The mixture may contain at up to four different cations. At least one of the cations is chosen to have a low reduction potential.
  • the cation may be chosen such that the reduction of the cation can be easily separated from the electrolyte. The reduction of the cation may produce a chemical of economic value, in addition to the product obtained from the decarboxylation.
  • the anion of the molten salt electrolyte may be chosen from the groups of halides, sulphonate, amides, tosylates, aluminate, borates, sulfates, nitrates, and carboxylates, or mixtures thereof.
  • the mixture of anions may include up to four different anions.
  • One of the anions may be chosen to have high oxidation potential. The oxidation potential is higher than that of the carboxylate anion being processed by the cell.
  • One of the anions chosen may be a carboxylate anion similar to the carboxylate being processed with the cell. In one embodiment, one of the anions is chosen such that it is the carboxylate being processed with the cell.
  • a salt of a carboxylic acid is dissolved into the molten salt electrolyte.
  • the carboxylate is chosen from acetate, propionate, lactate, butyrate, pentanoate, hexanoate, heptanoate, octanoate, laurate, oleate, stearate, linoleate, palmitate, myristrate, levulinate, valerate, benzoate, naphthenate and naphthoate or combinations thereof.
  • the products of the decarboxylation may be easily separated from the electrolyte.
  • the electrolyte comprises of a mixture of cations and anions.
  • the composition of the electrolyte may be such that a eutectic mixture is formed with a lower melting point than the melting point of the individual components of the mixture.
  • the electrolyte may contain as low as 2% of any particular component of a mixture and up to 98% of any particular component of the mixture.
  • the electrochemical cell may be operated at a temperature above the melting point of the molten salt electrolyte, but below the melting point of the products of the reduction and oxidation reactions.
  • the cell may be operated at a temperature above the melting point of the molten salt electrolyte and either of or both of the products of the reduction and oxidation reactions.
  • the electrochemical cell is operated at a temperature above the melting point of the molten salt and above the boiling point of the products of either or both the reduction and oxidation reactions.
  • the temperature of the cell may be optimized in order to promote the decarboxylation via lowering the activation energy of the decarboxylation and increasing the rate of CO 2 evolution.
  • an electrochemical cell comprises an anolyte compartment capable of housing a quantity of anolyte.
  • the anolyte may comprise a quantity of an alkali metal salt of a carboxylic acid dissolved in a molten salt electrolyte, wherein the alkali metal salt of the carboxylic acid has at least one functional group in addition to the carboxylic acid moiety.
  • the electrochemical cell may include an anode in communication with the anolyte, a catholyte compartment capable of housing a quantity of catholyte.
  • a cathode is in communication with the catholyte.
  • a membrane may separate the anolyte and catholyte.
  • a voltage source decarboxylates the alkali metal salt of the carboxylic acid into alkyl radicals that react to form a coupled radical products.
  • the analyte may be comprised of a molten salt electrolyte and may have similar cations and anions, alone or in respective mixtures.
  • the electrolyte may contain as low as 2% of any particular component of a mixture and up to 98% of any particular component of the mixture.
  • the composition of the catholyte may be the same or different than the anolyte.
  • the catholyte may be comprised of a dissolved salt in a polar solvent wherein the cation of the dissolved salt is chosen from those cations referenced herein throughout and mixtures thereof.
  • the anion of the dissolved salt may also be chosen from those anions referenced herein throughout and mixtures thereof.
  • the catholyte is comprised of a molten metal.
  • the molten metal may include lithium, sodium, potassium, magnesium and calcium and mixtures thereof.
  • the catholyte may be maintained at the same or different temperature as the anolyte.
  • the cell may be operated at a temperature above the melting point of the molten salt anolyte, but below the melting point of the products of the oxidation reaction. In some embodiments, the cell may be operated at a temperature above the melting point of the molten salt anolyte and of the products of the oxidation reaction.
  • the cell may be operated at a temperature above the melting point of the molten salt anolyte and above the boiling point of the products of the oxidation reaction.
  • the temperature of the cell may be optimized in order to promote the decarboxylation via lowering the activation energy of the decarboxylation and increasing the rate of CO 2 evolution.
  • the membrane separating the anolyte and catholyte compartments may be a cation exchange membrane.
  • the membrane may be a NaSICON (sodium super ion conducting) membrane or other ion selective membrane such as LiSICON (lithium super ion conducting).
  • the membrane comprises a thickness of between about 10 and about 5000 microns.
  • the membrane comprises a thickness of between about 100 and about 1000 microns.
  • the membrane comprises a thickness of between about 200 and about 700 microns.
  • the membrane may include either a planar configuration or a cylindrical configuration.
  • the catholyte compartment may include an outlet that is used to collect hydrogen gas, and the anolyte compartment may include an outlet that is used to collect the coupled radical product.
  • an electrochemical cell comprises an anolyte comprising a quantity of a salt of a carboxylic acid, wherein the salt of the carboxylic acid has at least one functional group in addition to the carboxylic acid moiety.
  • the cell includes an anode in communication with the anolyte and a catholyte in communication with the catholyte.
  • a voltage source decarboxylates the metal salt of the carboxylic acid into alkyl radicals that react to form a coupled radical product, wherein the coupled radical product has at least two functional groups.
  • an electrochemical cell comprises an anolyte comprising a quantity of salts of carboxylic acids, wherein at least one salt is an aryl carboxylic acid and at least another salt is an alkyl carboxylic acid.
  • the cell includes an anode in communication with the anolyte and a cathode in communication with the catholyte.
  • a voltage source decarboxylates the salt of the carboxylic acid into radicals that react to form homo- and hetero-coupled products, wherein the heterocoupled product has at least one alkyl and one aryl group.
  • an electrochemical cell comprises an anolyte comprising a quantity of salts of carboxylic acids, wherein the salts are saturated or mostly saturated carboxylic acids.
  • the cell includes an anode in communication with the anolyte and a cathode in communication with the catholyte.
  • a voltage source decarboxylates the salts of the carboxylic acids into radicals that react to form homo- and hetero-coupled products, wherein the products are saturated or mostly saturated hydrocarbons.
  • a method for producing a coupled radical product having at least two functional groups includes obtaining a salt of a carboxylic acid that has at least one functional group in addition to the carboxylic acid moiety, wherein the functional group consists of halide groups, sulfide groups, hydroxyl groups, amine groups, amide groups, and ether groups.
  • the method includes the step of decarboxylating the salt of the carboxylic acid into alkyl radicals that react to form a coupled radical product, wherein the coupled radical product has at least two of the functional groups.
  • the carboxylic acid may be derived from biomass.
  • the salt of the carboxylic acid may be formed via a saponification reaction using a base of the formula BOH or BOR, wherein, “B” represents a base and “OH” represents a hydroxide anion and “OR” represents an alkoxide anion.
  • B represents a base
  • OH represents a hydroxide anion
  • OR represents an alkoxide anion.
  • the base may be re-formed as part of the decarboxylation and the base may be collected and re-used in a further saponification reaction.
  • a method for producing a coupled radical product having both aryl and alkyl components includes the steps of obtaining a salt of an aryl carboxylic acid, and a salt of an alkyl carboxylic acid.
  • the method includes decarboxylating the salts of the carboxylic acid into radicals that react to form homo- and hetero-coupled product, wherein the heterocoupling product has at least one alkyl and one aryl group.
  • One of the carboxylic acids is derived from naphthenic acid.
  • the salts of the carboxylic acid are formed via a saponification reaction using a base of the formula BOH or BOR, wherein, “B” represents a base and “OH” represents a hydroxide anion and “OR” represents an alkoxide anion.
  • B represents a base
  • OH represents a hydroxide anion
  • OR represents an alkoxide anion.
  • the base is re-formed as part of the decarboxylation.
  • a method for producing a coupled radical product which is a saturated or mostly saturated hydrocarbon includes the steps of obtaining a salt or salts of saturated carboxylic acids, decarboxylating the salt or salts of the carboxylic acids into radicals that react to form homo- and hetero-coupled products, wherein the products are saturated or mostly saturated hydrocarbons.
  • the salt of the carboxylic acid may be derived from biomass.
  • the salts of the carboxylic acids may be formed via a saponification reaction using a base of the formula BOH or BOR, wherein, “B” represents a base and “OH” represents a hydroxide anion and “OR” represents an alkoxide anion.
  • the base may be re-formed as part of the decarboxylation, wherein the base is collected and re-used in a further saponification reaction.

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Publication number Priority date Publication date Assignee Title
US20150083606A1 (en) 2013-09-24 2015-03-26 Ceramatec, Inc. Molten Carboxylate Electrolytes for Electrochemical Decarboxylation Processes

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4617098A (en) * 1982-08-31 1986-10-14 Rhone-Poulenc Specialites Chimiques Continuous electrolysis of lithium chloride into lithium metal
US20060102489A1 (en) * 2004-10-29 2006-05-18 Kelly Michael T Methods and apparatus for synthesis of metal hydrides
US20090194426A1 (en) * 2005-07-06 2009-08-06 University Of Leicester Eutectic mixtures based upon multivalent metal ions
US20110027848A1 (en) * 2009-07-23 2011-02-03 Mukund Karanjikar Method of producing coupled radical products from biomass
US20110024288A1 (en) * 2009-07-23 2011-02-03 Sai Bhavaraju Decarboxylation cell for production of coupled radical products
US20110111475A1 (en) * 2009-04-17 2011-05-12 Kuhry Anthony B Biological/Electrolytic Conversion of Biomass to Hydrocarbons
US20110226633A1 (en) * 2009-07-23 2011-09-22 Sai Bhavaraju Electrochemical synthesis of aryl-alkyl surfacant precursor
US20110272291A1 (en) * 2006-02-08 2011-11-10 Stapley Jonathan A Methods for the electrolytic production of erythritol
US20130186770A1 (en) * 2009-07-23 2013-07-25 Ceramatec, Inc. Device and method of obtaining diols and other chemicals using decarboxylation

Family Cites Families (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3808051A (en) * 1972-06-23 1974-04-30 Church & Dwight Co Inc Cleaning method and compositions
US4560775A (en) * 1983-06-13 1985-12-24 Monsanto Company Production of lactone in molten salt electrolysis
US5423454A (en) * 1992-08-19 1995-06-13 Lippman, Deceased; Lawrence G. Method of propellant gas generation
US6238543B1 (en) * 1997-10-17 2001-05-29 E. I. Du Pont De Nemours And Company Kolbe electrolysis in a polymer electrolyte membrane reactor
ATE307109T1 (de) 1999-08-30 2005-11-15 Mossi & Ghisolfi Int Sa Alkyl-carboxylat-salze als lösungsmittel für henkel-verwandte prozesse
AU6897700A (en) * 1999-08-30 2001-03-26 Shell Internationale Research Maatschappij B.V. Process for making an aromatic diacid in one step using a single catalyst system
GB0116505D0 (en) * 2001-07-06 2001-08-29 Univ Belfast Electrosynthesis of organic compounds
EP1312700A3 (de) 2001-11-02 2003-05-28 Degussa AG Verfahren zur Herstellung von Alkalialkoholaten
US7141154B2 (en) * 2003-03-06 2006-11-28 Uchicago Argonne Llc Single-stage separation and esterification of cation salt carboxylates using electrodeionization
JP5314246B2 (ja) 2003-12-11 2013-10-16 アメリカン パシフィック コーポレイション イオン伝導性セラミックの固体膜を用いたアルカリアルコラートを生成するための電気分解による方法
US8075758B2 (en) 2003-12-11 2011-12-13 Ceramatec, Inc. Electrolytic method to make alkali alcoholates using ion conducting alkali electrolyte/separator
WO2007027669A1 (en) * 2005-08-29 2007-03-08 Cps Biofuels, Inc. Improved biodiesel fuel, additives, and lubbricants
JP2009041076A (ja) * 2007-08-09 2009-02-26 Asahi Glass Co Ltd 含フッ素化合物の製造方法
US20100307927A1 (en) * 2009-06-09 2010-12-09 Richard Price Method of making synthetic petroleum components
US20130245347A1 (en) * 2009-07-23 2013-09-19 Ceramatec, Inc. Device and method for aryl-alkyl coupling using decarboxylation
WO2011123817A2 (en) * 2010-04-01 2011-10-06 Ceramatec, Inc. Production of alkali bicarbonate and alkali hydroxide from alkali carbonate in an electrolytic cell
KR101760971B1 (ko) * 2010-04-23 2017-08-04 세라마테크, 인코오포레이티드 아릴-알킬 계면활성제 전구체의 전기화학 합성
EP2668250B1 (en) * 2011-01-25 2019-04-24 Enlighten Innovations Inc. Production of fuel from chemicals derived from biomass
US8961775B2 (en) * 2011-02-01 2015-02-24 Altranex Corporation High productivity Kolbe reaction process for transformation of fatty acids derived from plant oil and animal fat
EP2804967B1 (en) * 2012-01-16 2019-06-19 Enlighten Innovations Inc. Composite alkali ion conductive solid electrolyte
US20150083606A1 (en) 2013-09-24 2015-03-26 Ceramatec, Inc. Molten Carboxylate Electrolytes for Electrochemical Decarboxylation Processes

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4617098A (en) * 1982-08-31 1986-10-14 Rhone-Poulenc Specialites Chimiques Continuous electrolysis of lithium chloride into lithium metal
US20060102489A1 (en) * 2004-10-29 2006-05-18 Kelly Michael T Methods and apparatus for synthesis of metal hydrides
US20090194426A1 (en) * 2005-07-06 2009-08-06 University Of Leicester Eutectic mixtures based upon multivalent metal ions
US20110272291A1 (en) * 2006-02-08 2011-11-10 Stapley Jonathan A Methods for the electrolytic production of erythritol
US20110111475A1 (en) * 2009-04-17 2011-05-12 Kuhry Anthony B Biological/Electrolytic Conversion of Biomass to Hydrocarbons
US20110027848A1 (en) * 2009-07-23 2011-02-03 Mukund Karanjikar Method of producing coupled radical products from biomass
US20110024288A1 (en) * 2009-07-23 2011-02-03 Sai Bhavaraju Decarboxylation cell for production of coupled radical products
US20110226633A1 (en) * 2009-07-23 2011-09-22 Sai Bhavaraju Electrochemical synthesis of aryl-alkyl surfacant precursor
US20130186770A1 (en) * 2009-07-23 2013-07-25 Ceramatec, Inc. Device and method of obtaining diols and other chemicals using decarboxylation

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
Conway et al, New Approaches to the Study of Electrochemical Decarboxylation and the Kolbe Reaction: Part I. The Model Reaction with Formate, Canadian Journal of Chemistry, Vol. 41, No. 1, January 1963, pp. 21-37 *
Conway et al, New Approaches to the Study of Electrochemical Decarboxylation and the Kolbe Reaction: Part II. The Model Reaction with Trifluoroacetate and Comparisons with Aqueous Solution Behavior, Canadian Journal of Chemistry, Vol. 41, No. 1, January 1963, pp. 38-54 *
Conway et al, New Approaches to the Study of Electrochemical Decarboxylation and the Kolbe Reaction: Part III. QUANTITATIVE ANALYSIS OF DECAY AND DISCHARGE TRANSIENTS AND THE ROLE OF ADSORBED, Canadian Journal of Chemistry, Vol. 41, No. 1, January 1963, pp. 55-67 *
Hicks et al, Kolbe Electrolysis of Acetic Acid in a Polymer Electrolyte Membrane Reactor, Journal of the Electrochemical Society, Vol. 145, No. 11, November 1998, pp. 3728-3734 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20150267316A1 (en) * 2014-03-19 2015-09-24 Sandia Corporation Electrochemical Ion Separation in Molten Salts
US10450660B2 (en) 2014-11-04 2019-10-22 Savannah River Nuclear Solutions, Llc Recovery of tritium from molten lithium blanket

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