WO2004015171A2

WO2004015171A2 - Magnetically-enhanced electrolytic cells for generating chlor-alkali and methods related thereto

Info

Publication number: WO2004015171A2
Application number: PCT/US2003/023587
Authority: WO
Inventors: Shelley Minteer
Original assignee: Saint Louis University
Priority date: 2002-07-31
Filing date: 2003-07-28
Publication date: 2004-02-19
Also published as: AU2003256941A1; US20040020785A1; WO2004015171A3; AU2003256941A8

Abstract

An electrolytic cell for producing a chlor-alkali including at least two electrodes in reactive contact with an aqueous liquid containing a chloride salt, wherein at least one of the electrodes is within a magnectic field is described herein.

Description

MAGNETICALLY-ENHANCED ELECTROLYTIC CELLS FOR GENERATING CHLOR- ALKALI AND METHODS RELATED THERETO

CROSS-REFERENCE TO RELATED APPLICATIONS

Not applicable. STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

FIELD OF THE INVENTION

This invention relates to electrolytic cells for producing chlor-alkahs from chloride salt- containing aqueous liquids. In particular, this invention relates to electrolytic cells for producing chlor-alkalis from chloride salt-containing aqueous liquids comprising magnetically- modified electrodes.

BACKGROUND OF THE INVENTION

Chlorine has many uses in the safety, health and environmental industries. It is needed in the production of 85% of all pharmaceuticals, 45% of all commercial products, and 96% of all crop protection chemicals. Chlorine is also used to disinfect 98% of the water supply. As such, the chlor-alkali process is one of the most economically important electrosynthetic processes.

The traditional electrochemical chlor-alkali process is the process most widely used to produce chlorine. This process involves the electrolysis of salt water to form chlorine gas, sodium hydroxide and hydrogen gas, which are also referred to as chlor-alkahs. The traditional electrochemical chlor-alkali process involves a series of process steps that are not fully defined. However, it is known that chloride ions adsorb to the catalyst surface, a series of electrochemical steps occur, and then chlorine gas desorbs from the surface. At the cathode, protons adsorb to the catalyst's surface, a series of steps occur, and hydrogen gas desorbs from the surface.

1938104 Over the last fifty years, three types of chlor-alkali cells have been used in this process: mercury, diaphragm and membrane. The mercury cells were most popular until mercury contamination became a problem. As such, mercury cells are being phased out worldwide. Diaphragm cells consist of an anode and a cathode that are separated by an asbestos diaphragm supported by a steel net. This cell is problematic because hydroxide ions can diffuse across the asbestos diaphragm and dramatically decrease cell efficiency and lifetime. Today, the majority of electrochemical chlor-alkali cells are membrane cells. Membrane cells consists of a metallic cathode and a ruthenium or rhodium based anode separated by a cation selective membrane.

While each cell produces chlorine, poor kinetics and selectivity make these traditional cells undesirable. Poor selectivity results from the standard reduction potentials of reactants being too close together. For example, if you apply 1.0 Volts (V) to an electrode, every reactant in solution with a standard potential of 1.0 V or less will electrolyze. This causes many unwanted secondary reactions to occur at both the anode and cathode. For example, one reaction decreases the amount of sodium hydroxide produced in the system and contaminates the chlorine gas with oxygen. Other reactions produce chlorate, which contaminates sodium hydroxide and corrodes the membrane cell. Many other reactions are possible at the cathode and anode depending on the impurities in brine, but these reactions are prevalent and destructive in brine that has been purified. Further, these unwanted secondary reactions increase energy consumption and decrease efficiency.

Moreover, traditional chlor-alkali processes involve at least two additional steps to produce a chlor-alkali, requiring more resources and further decreasing efficiency. First, the brine solution must be purified before electrolysis. Second, the water must be evaporated from the sodium hydroxide, to further concentrate the sodium hydroxide and remove the oxygen from the chlorine gas.

1938104 - 2 - Accordingly, a need exists for an electrolytic cell for producing a chlor-alkali that has increased kinetics, selectivity and efficiency when compared to traditional electrolytic chlor- alkali cells.

BRIEF SUMMARY OF THE INVENTION

In one aspect of the invention, an electrolytic cell for producing a chlor-alkali is provided that comprises at least two electrodes in reactive contact with an aqueous liquid containing a chloride salt, wherein at least one of the electrodes is within a magnetic field.

In a second aspect of the invention, an electrolytic cell for producing a chlor-alkali is provided that comprises at least two electrodes in reactive contact with an aqueous liquid containing a chloride salt, wherein at least one of the electrodes is within a magnetic field and formed by applying a magnetic coating onto the surface of the electrode to aid in producing the chlor-alkali.

In a third aspect of the invention, an electrolytic cell for producing a chlor-alkali is provided that comprises at least two electrodes in reactive contact with an aqueous liquid containing a chloride salt, wherein at least one of the electrodes is within a magnetic field and formed by applying a magnetic coating onto the surface of the electrode to aid in producing the chlor-alkali, wherein the magnetic coating comprises at least one encapsulated magnetic microparticle or icrosphere, a binding agent and a catalyst.

In a fourth aspect of the invention, a method for producing a chlor-alkali from an aqueous liquid containing a chloride salt is provided that comprises inducing an electrolytic reaction between at least two electrodes in reactive contact with the aqueous liquid, at least one of said electrodes being within a magnetic field to aid in producing the chlor-alkali.

In a fifth aspect of the invention, a method for producing a chlor-alkali from an aqueous liquid containing a chloride salt is provided that comprises inducing an electrolytic

1938104 reaction between at least two electrodes in reactive contact with the aqueous liquid, wherein at least one of the electrodes is within a magnetic field and formed by applying a magnetic coating onto the surface of the electrode to aid in producing the chlor-alkali.

In a sixth aspect of the invention, a method for producing a chlor-alkali from an aqueous liquid containing a chloride salt is provided that comprises inducing an electrolytic reaction between at least two electrodes in reactive contact with the aqueous liquid, wherein at least one of the electrodes is within a magnetic field and formed by applying a magnetic coating onto the surface of the electrode to aid in producing the chlor-alkali, wherein the magnetic coating comprises at least one encapsulated magnetic microsphere or microparticle, a binding agent and a catalyst.

In a seventh aspect of the invention, products produced by the above-identified methods are provided.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

Figure 1 illustrates cyclic voltammograms of a magnetic microsphere/Nafion^® composite modified glassy carbon anode and a Nafion^® film modified glassy carbon anode in a 0.1M artificial brine solution;

Figure 2 illustrates representative cyclic voltammograms for a magnetic microsphere/PVP composite modified glassy carbon anode and a PVP film modified glassy carbon anode in a 0.1M artificial brine solution;

Figure 3 illustrates representative cyclic voltammograms of a magnetic microsphere/Nafion^® modified cathode and a Nafion^® modified cathode in a 0.1M artificial brine solution,-

1938104 - 4 Figure 4 illustrates representative cyclic voltammograms of a magnetic microsphere/PVP composite modified cathode and a PVP modified cathode in a 0.1M artificial brine solution,- and

Figure 5 illustrates representative cyclic voltammograms of a 15% by weight magnetic microsphere/15% by weight ruthenium black/70% by weight Nafion^® composite modified anode and a 15% by weight ruthenium black/85% by weight Nafion^® composite modified anode in a 0.1M artificial brine solution.

DETAILED DESCRIPTION OF THE INVENTION

In accordance with the present invention, it has been discovered that if a chlor-alkah reaction is carried out with at least one of the electrodes in a chlor-alkah electrolytic cell within a magnetic field, the reaction exhibits surprisingly superior kinetics, selectivity and efficiency when compared to traditional chlor-alkah cells. As used herein, the term "chlor-alkah" refers to any product of the electrolytic cells or methods of the present invention. As such, the term chlor-alkah refers to chlorine gas, hydrogen gas, sodium hydroxide, chlorites, potassium hydroxide, hypochlorates, perchlorates and chlorates. The electrolytic cell of the invention comprises at least two electrodes in reactive contact with an aqueous hquid containing a chloride salt, wherein at least one of the electrodes is within a magnetic field. An electrolytic reaction is induced between at least two of the electrodes inside the cell to produce the chlor- alkah. Generally, adsorption/desorption processes reach equilibrium. At this stage, an abundance of molecules are adsorbed to the catalyst surface, which reduces adsorption and desorption. However, since the electrochemical process electrolyzes each molecule that gets adsorbed to the electrode surface, equihbrium is never reached. Instead more molecules are allowed to adsorb to the clean surface, thereby increasing adsorption and desorption events,

1938104 - 5 - and frequently making the kinetics of the adsorption and desorption steps the rate hmiting steps.

Although the present inventor does not wish to be bound to any particular theory of operation, it is believed that the method of the present invention operates according to the following concept. Magnetic fields have been shown to increase and decrease electrochemical flux due to magnetohydrodynamic effects and gradient magnetic field enhanced mass transport. The key to both of these effects is the presence of paramagnetic reactants, products, or electrolytes, which are not employed in traditional chlor-alkah processes. While a magnetic field would not affect the hydrodynamics or mass transport of chloride ions and protons to the electrode surface, magnetic fields can affect the electron transfer rates through spin polarization. Alteration of the electron transfer rates can, in turn, alter the reaction pathways and product distributions of electron transfer reactions with one or more free radical reactant, product, or intermediate. Although the electrolytic cells of the invention do not employ paramagnetic reactants or products, paramagnetic intermediates and adsorbates are present. These paramagnetic intermediates and adsorbates have the potential to be susceptible to magnetic field effects through spin polarization.

Thus, it is believed that the increased kinetics of the electrolytic cells of the present invention are due to magnetoadsorption and magnetodesorption effects, also referred to magnetic-field-induced adsorption and desorption, as well as spin polarization. When a molecule adsorbs to a catalyst surface, there is a partial electron transfer that occurs as they share electron density. This partial electron transfer is dependent on the external magnetic field. If the adsorption/desorption process causes a delocalization of the charge density from the spin density, and the overall magnetizabihty is changed during the adsorption process. Experimental evidence shows that there are magnetoadsorption and magnetodesorption effects

1938104 - 6 - of diamagnetic adsorbing molecules. Therefore, no unpaired electron is necessary and magnetic fields can affect the adsorption and desorption of the overall electron transfer reactions at the anode and cathode.

Magnetoadsorption and magnetodesorption effects are crucially important, because they can be easily tailored to a given reaction system by modifying the existing catalyst with additives for promoting and inhibiting the magnetoadsorption and magnetodesorption effects. Theoretically, any adsorption/desorption limited electron transfer mechanism can be improved and its secondary reaction rates decreased by tailoring the existing catalysts with additives that promote the s-d exchange interaction for the primary reaction and inhibit the interaction for the secondary reactions, which is a definite advantage to other magnetic field effects that are independent of the catalysts, e.g. spin polarization, magnetohydrodynamic, etc. For example, molecules that act as spin traps effectively change the magnetic polarization of materials they contact. Examples of such molecules include paramagnetic lanthanide and transition metals.

The electrolytic cells for producing a chlor-alkah of the invention comprise at least two electrodes in reactive contact with an aqueous hquid containing a chloride salt, wherein at least one of the electrodes is within a magnetic field. The aqueous hquid utilized may be any aqueous hquid containing a chloride salt. In many situations, the aqueous hquid is an aqueous solution of a chloride salt, such as an alkali metal chloride, for instance, potassium chloride or, more commonly, sodium chloride. In traditional electrochemical chlor-alkah cells, brine solution is converted to concentrated sodium hydroxide, chlorine gas and hydrogen gas. The electrolytic cells of the invention also convert brine solution to concentrated sodium hydroxide, chlorine gas and hydrogen gas. However, the electrolytic cells of the invention are not hmited to the production of such chlor-alkahs. Other products of the chlor-alkah process are within the scope of the invention. For example, the electrolytic cells of the invention convert

1938104 - 7 - potassium chloride-containing aqueous hquids to potassium hydroxide, hypochlorites, chlorates and perchlorates. It is also within the scope of the present invention to produce other products from the conversion of chloride-containing aqueous hquids, e.g. chlorites. Further examples of such products are found in Carl H. Hamann et al., Electrochemistry, Chapter 8, 319-320 (Wiley : New York 1998), which is hereby incorporated by reference.

At least two electrodes are in reactive contact with the aqueous hquid and at least one of the electrodes of the invention is located within a magnetic field during electrolysis of the aqueous hquid. By "reactive contact" what is meant is that the at least two electrodes are within a distance to the aqueous hquid such that the electrodes are able to aid in converting the chloride salt-containing aqueous liquid to a chlor-alkah. Accordingly, the electrodes need not be within or surrounded by the aqueous hquid, it is only necessary that a portion of each electrode is in contact with the hquid. As used herein, an electrode is "within a magnetic field" when the electrode is itself magnetized or comprises magnetic material therein, when at least part of the electrode is coated with a substance comprising a magnetic material, and when the electrode is adjacent to, in magnetic contact with, or surrounded by a magnetic field. In one embodiment of the invention, the electrode that is within a magnetic field has a magnetic coating on its surface. In a second embodiment of the invention, the electrode that is witliin a magnetic field is formed by exposing the electrode to an external magnetic force that comes into reactive contact with the electrode.

Any type of cathode and any type of anode may be used. In one embodiment of the invention, one or more platinum working electrodes are used for the cathode. Further, or in a second embodiment of the invention, one or more carbon working electrodes are used for the anode.

1938104 - 8 Any substance having magnetic properties may be used as the magnetic coating of the invention. In a specific embodiment, the magnetic coating comprises at least one encapsulated magnetic microsphere or microparticle, a binding agent and a catalyst. As used herein the term "microsphere" is used interchangeably with the term "microparticle." The microspheres or microparticles of the invention are small enough to provide an adequate surface area to volume to impart a magnetic field, while large enough to avoid becoming superparamagnetic. In one embodiment of the invention, the microspheres or microparticles have a weight average diameter of about 0.5 microns to about 12 microns, although microspheres or microparticles having diameters outside of this range may also be utilized in the present invention. The composition of the microspheres or microparticles employed is also not critical, so long as magnetic properties are exhibited therefrom. Suitable microspheres or microparticles comprise magnetite or rust, samarium cobalt, neodymium iron boron, other iron based magnets, magnetic semiconducting materials, molecular magnets and ferrofluids. The magnetic microsphere or microparticle may also be a silane encapsulating microsphere or microparticle.

The encapsulated magnetic microsphere or microparticle of the invention is formed by coating an encapsulating material onto the surface of the microsphere or microparticle. The encapsulating material may be applied onto the microparticle or microsphere by any known encapsulating process. It is not necessary that the entire surface of the microparticle or microsphere be coated with the encapsulating material. Only part of the surface must be coated.

Any encapsulating material that is impermeable to ions, gas and other substances may be employed. Specifically, the encapsulating material of the invention should be impermeable to oxygen, ions, and gases that may escape from the magnetic microsphere or microparticle or enter into the aqueous hquid of the invention. Impermeability to oxygen is critical because

1938104 exposure of the magnetic microparticles or microspheres to oxygen would cause corrosion of the microparticles or microspheres. Further, the escape of ions, for example iron ions, from the magnetic microsphere or microparticle would contaminate the aqueous hquid, producing impurities that could negatively effect the conversion process. In one embodiment of the invention the encapsulating material is a polymer. Any polymer may be used, including but not hmited to polystyrene, polyvinylpropyhne, a perfluorinated polymer, a conducting polymer, a polytetrafluoroethylene, a co-polymer, a polymer composite, or any combination thereof. In another embodiment, the encapsulating material comprises glass, a sol-gel material, semiconductor materials, at least one high-temperature ceramic, or a metal.

In one embodiment of the invention a binding agent is employed in the magnetic coating of the invention to secure the magnetic microparticles and catalyst onto the surface of the electrode, thereby placing the electrode within a magnetic field. The binding agent may be any binding agent that is permeable to ions, gases and other substances. The binding agent may be made of the same materials as the encapsulating material. However, the binding agent must be altered such that it is permeable to ions, gases and other substances. Since the binding agent acts to bind the magnetic coating onto the surface of the electrode it is critical that the binding agent not act to inhibit or restrain the interaction of the catalyst and/or magnetic microparticles or microspheres employed with the other reactants present in the electrolytic ceU. Accordingly, and in one embodiment of the invention, the binding agent is a polymer that is permeable to ions, gases, and other substances. Any polymer may be used, including but not limited to polystyrene, polyvinylpropyline, a perfluorinated polymer, a conducting polymer, a polytetrafluoroethylene, a co-polymer, a polymer composite, or any combination thereof. In another embodiment, the binding agent comprises glass, a sol-gel

1938104 - 10 material, semiconductor materials, at least one high-temperature ceramic, or a metal that is permeable to ions, gases and other substances.

The permeability of the encapsulating materials and/or binding agents may be altered by means well-known in the art. For example, the pore size of the encapsulating material and/or binding agent may be manipulated by heating and/or pressurizing processes. The process used to alter the permeability of the encapsulating material and/or binding agent is dependent upon the specific material or agent employed. These processes are well known in the art.

It should be noted that the use of a binding agent in the magnetic coating is not critical to the invention. For example, and in one embodiment of the invention, the catalyst itself has magnetic properties, and no magnetic microspheres or microparticles are employed in the magnetic coating of the invention. If the magnetic catalyst is sputter coated onto the electrode, no binding agent is employed. Examples of catalysts with magnetic properties include lanthanide-based semi-conducting catalysts, nickel and cobalt. Accordingly, the magnetic coating of the invention comprises a magnetic catalyst.

In yet another specific embodiment, the catalyst is coated directly onto the magnetic microsphere or microparticle. The coating may be accomplished using any known coating technique, e.g. sputter coating onto the electrode surface. A binding agent would not be employed in this embodiment.

One advantage of the electrolytic cells of the invention is that conventional catalysts may be used. Any catalyst that is suitable for use in electrochemical cells may be employed. However, ruthenium black is the preferred catalyst for the anode, and carbon black is the preferred catalyst for the cathode because they have high surface areas and are very stable. Other suitable catalysts include, but are not limited to platinum black, platinized carbon,

1938104 - 11 - metals, metal oxides, or magnetocatalysts. It should be noted that magnetoadsorption/ desorption effects could be altered by adding additives or impurities to the catalyst that will promote the desired magnetoadsorption/desorption effect.

Preferably, the magnetic coatings of the invention generally comprise about 10% to about 20% by weight magnetic microparticle or microsphere, about 10% to about 20% by weight catalyst, and about 65% to about 75% by weight binding agent after evaporation of any solvents present. However, concentrations outside of this range are also within the scope of the present invention.

In a specific embodiment of the invention, the binding agent itself has magnetic properties, and no magnetic microspheres or microparticles are employed in the magnetic coating of the invention. Accordingly, this magnetic coating of the invention comprises a magnetic binding agent and a catalyst.

The electrodes of the invention that are within a magnetic field may be formed by exposing the electrodes to an external magnetic field, that comes into magnetic contact with the electrode. The application of a magnetic coating onto the surface of the electrode is not required. However, in one embodiment of the invention, electrodes that have a magnetic coating thereon are also exposed to an external magnetic field to give the magnetic coating an ordered structure that increases the reducibihty and magnetic effects. In this embodiment, the external magnetic field must be strong enough to cause order, but not so strong that the magnetic material is removed from the electrode and propelled to the magnet. One external magnet suitable for use in the methods of the invention is the 0.2T iron composite magnet that is cylindrical with a 1.0 inch hole in the middle, commercially available from Edmund Scientific. However, any magnet suitable to cause the electrode to be within a magnetic field may be used.

L938104 - 12 - All references and patents cited herein are hereby incorporated by reference in their entireties for their relevant teachings. Accordingly, any reference cited herein and not specifically incorporated by reference is, nevertheless, incorporated by reference in its entirety as if part of the present specification.

The following examples illustrate specific embodiments of the invention without limiting the scope of the invention in any way. Numerous modifications and variations of the present invention are readily apparent to those of skill in the art. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically claimed.

EXAMPLES EXAMPLE 1 - Preparation of Microspheres

Polystyrene shrouded magnetic microspheres were used as received from Polysciences, Inc. The microspheres varied in size, ranging from 0.5 to 10 microns. Polystyrene microspheres of the same size were used as received from Polysciences, Inc.

Silane coated magnetic microspheres were synthesized by placing magnetite powder, which is less than five microns in size, in a 50/50 mixture of 3-aminopropyltrimethoxysilane and toluene. The solution was mixed on a vortex overnight at room temperature. After rinsing the microspheres with toluene, the microspheres were placed in a 50/50 mixture of ethylene glycol diglycidyl ether and water. The mixture was then vortexed overnight at room temperature. The microspheres were then rinsed and dried.

EXAMPLE 2 - Magnetized Electrode Coating

Magnetic coatings were made from 5% by weight Nafion^® suspension, which is a perfluorinated ionomer that is commerciaUy available from Dupont in Wilmington, Delaware, or 5% by weight 4-polyvinylpyridine in methanol, the magnetic microspheres prepared in

1938104 - 13 - Example 1, and a catalyst. The catalysts prepared were ruthenium black for the anode and carbon black for the cathode.

The magnetic coatings were prepared in such a way that the dry film existing after the solvents evaporated was 15% by weight magnetic microparticles or microspheres, 15% by weight catalyst, and 70% by weight polymer. The magnetic coating was vortexed overnight to insure thorough mixing of the material, and to decrease clumping of the magnetic material and/or catalysts. The vortexed magnetic coating was pipetted onto the two electrodes. Platinum working electrodes were used for the cathode and carbon working electrodes were used for the anode. Once the magnetic coating was pipetted onto the electrodes, the solvents were allowed to evaporate either in the presence or the absence of an external magnetic field. The external magnetic field used was a 0.2T iron composite magnet that was cylindrical with a 1.0 inch hole in the middle. The magnet is commerciaUy available from Edmund Scientific. The surface of the electrode was placed at the bottom edge of the magnet's hole so that a minimal magnetic field was applied to the particles. Once the electrodes were dry, they were removed from the external magnetic field and placed into a vacuum desiccator overnight to ensure the removal of the solvent.

EXAMPLE 3 - Electrochemical Measurements

A 0.1M artificial brine solution was made from 18 Mega ohm water. Both transient and steady state electrochemical measurements were taken in order to get information about the selectivity and kinetics of the methods of Examples 1 and 2. Cychc voltammetry was the transient method employed and bulk electrolysis was the steady state method. Since both reactions were near the edge of potential window for water, there was no detectable peak at the scan rates from 50 mV/s to 250 mV/s that were employed. Therefore, flux effects were letermined from the current at the final potential of the cychc voltammogram and the bulk

938104 - 14 - electrolysis data. Both methods were performed with a standard three-electrode electrochemical ceU. The working electrode was either the magneticaUy modified electrode or a control electrode. The counter electrode was platinum gauze. The reference electrode was a shVer/silver chloride electrode. AU measurements were performed on a CH Instruments Model 620 A Potentiostat that was interfaced to a Pentium computer. The CH Instruments software was used for data acquisition and analysis.

The effect on the polymers in the magnetic modification process were examined first. The two polymers tested were Nafion^® and polyvinyl pyridine (PVP). If the interface allowed for pre-concentration of the analyte, chlorine ions for the anode and hydrogen ions for the cathode, then magnetic effects would be proved. If the interface was not conducive to pre- concentration of the analyte or facile transport of the analyte to the surface of the catalyst/electrode, then a smaU decrease in the flux due to the addition of the magnetic material would have been present.

The results are shown in Figures 1 and 2. Figure 1 iUustrates representative cychc voltammograms of a 15% magnetic microsphere/85% Nafion^® composite modified anode and a Nafion^® film modified anode in a 0.1M sodium chloride solution. The final peak current for the magnetic microparticle/ Nafion^® composites was a factor of 3.22 ± 0.08 larger than the final peak current of the non-magneticaUy modified electrode (Nafion^® film). This is indicative of a substantial magnetic effect with Nafion^® as the polymer that binds the magnetic microparticle to the surface of the electrode.

Figure 2 iUustrates representative cychc voltammograms for a 15% magnetic microsphere/85% PVP composite modified anode and a PVP film modified anode in a 0.1M sodium chloride solution. The final peak currents for the magnetic microparticle/PVP composite electrodes were slightly smaUer than the final peak currents of the PVP modified

1938104 - 15 - electrodes. This indicates that the interface between the PVP and the magnetic microparticles was not conducive to the pre-concentration of chloride ions.

Therefore, catalyst studies on the anode were performed with Nafion^® as the polymer binder. The polystyrene microsphere controls (15% polystyrene microsphere/85% polymer composites) produced the same results as the pure PVP and Nafion^® film controls within the error in the measurements.

Figures 3 iUustrates representative cychc voltammograms of a 15% magnetic microsphere/85% Nafion^® composite modified cathode and a Nafion^® modified cathode in a 0.1M sodium chloride solution. The final peak currents of the magnetic microparticle/ Nafion^® composite electrodes were slightly smaUer than the final peak currents of the Nafion^® composite electrodes. This is indicative that the interface between the Nafion^® and the magnetic microparticle was not conductive to the preconcentration of hydronium ions, although there was some indication that there were some smaU magnetic effects on the adsorption and desorption to the electrode/catalyst, which was platinum. This effect was seen in the alteration of the adsorptive area of the cychc voltammogram from 0 to -.075 V.

Figure 4 contains representative cychc voltammograms of a 15% magnetic microsphere/85% PVP composite modified cathode and a PVP film modified cathode in a 0.1M sodium chloride solution. On average, the final peak currents of the magnetic microparticle/PVP composite cathodes were 91% larger than the final peak current for the PVP electrodes. This along with the dramatic alteration of the adsorptive area of the cychc voltammograms indicated a positive magnetic field effect. Therefore, further catalyst experiments on the cathode were performed with PVP as the polymer binder. The polystyrene microsphere controls produced the same results as the pure polymer film controls within the error in the measurements.

1938104 - 16 - Experiments were also conducted on the Polysciences magnetic microspheres, but there was no statistical difference in the electrochemical flux of any of the anodes or cathodes by changing from Polysciences magnetic microspheres to the silane encapsulated magnetic microparticles.

Catalyst experiments were performed on the anode using ruthenium black as the catalyst. Figure 5 iUustrates representative cychc voltammograms of the catalyst experiments on the anode. The cychc voltammograms show that the catalyst further enhanced the magnetic filed effect. The bulk electrolysis results for the magnetic microsphere/ruthenium black/ Nafion^® composites showed that the flux, or current density, was 6.32 ± 2.15 times the flux of a ruthenium black/ Nafion^® composite.

Catalyst experiments were also performed on the cathode using carbon black. However, the voltammograms were analogous to the magnetic microparticle/PVP composite modified electrodes shown in Figure 4.

The electrodes produced chlorine gas, which was visuaUy observed, hydrogen gas and hydroxide ions. It is weU accepted in the art that for each mole of hydroxide ion that is produced by electrolysis of sodium chloride in aqueous solution, 1/2 mole of chlorine gas and 1/2 mole of hydrogen gas is produced. Thus, production of chlorine gas and hydrogen gas can be inferred from the direct measurement of hydroxide ion production. The number of moles of hydroxide produced in the brine solution was determined by titration. It was found that the magnetic microparticle/carbon black/PVP modified cathode of the instant invention produced 64.4 times the hydroxide ions (and therefore 64.4 times the chlorine gas and hydrogen gas) as the carbon black/PVP modified cathode. Accordingly, the amount of current required to generate any given amount of chlor-alkah products is reduced by approximately 91% by use of an

1938104 - 17 - electrolytic ceU of the instant invention.

1938104 - 18

Claims

What is claimed is:

1. An electrolytic ceU for producing a chlor-alkah comprising at least two electrodes in reactive contact with an aqueous hquid containing a chloride salt, wherein at least one of the electrodes is within a magnetic field.

2. The electrolytic ceU of claim 1 wherein said chlor-alkah is chlorine gas.

3. The electrolytic ceU of claim 1 wherein said chlor-alkah is hydrogen gas.

4. The electrolytic ceU of claim 1 wherein said chlor-alkah is sodium hydroxide.

5. The electrolytic ceU of claim 1 wherein said chlor-alkah is potassium hydroxide.

6. The electrolytic ceU of claim 1 wherein said chlor-alkah is a hypochlorite.

7. The electrolytic ceU of claim 1 wherein said chlor-alkah is a chlorate.

8. The electrolytic ceU of claim 1 wherein said chlor-alkah is a chlorite.

9. The electrolytic ceU of claim 1 wherein said chlor-alkah is a perchlorate.

10. The electrolytic ceU of claim 1 wherein said electrode is a platinum working cathode.

11. The electrolytic ceU of claim 1 wherein said electrode is a carbon working anode.

12. The electrolytic ceU of claim 1 wherein said at least one electrode is formed by applying a magnetic coating onto the surface of the electrode.

13. The electrolytic ceU of claim 12 wherein said magnetic coating comprises at least one encapsulated magnetic microparticle or microsphere, at least one binding agent and at least one catalyst.

14. The electrolytic ceU of claim 13 wherein said magnetic coating comprises about 10% to about 20% said encapsulated magnetic microparticle or microsphere, about 10% to about 20% said at least one catalyst and about 65% to about 75% said at least one binding agent.

15. The electrolytic ceU of claim 13 wherein said catalyst is carbon black.

16. The electrolytic ceU of claim 13 wherein said catalyst is ruthenium black.

1938104 - 19 -

17. The electrolytic ceU of claim 13 wherein said catalyst is platinum black.

18. The electrolytic ceU of claim 13 wherein said catalyst is platinized carbon.

19. The electrolytic ceU of claim 13 wherein said catalyst is a magnetocatalyst.

20. The electrolytic ceU of claim 13 wherein said catalyst is a metal or metal oxide.

21. The electrolytic ceU of claim 13 wherein said encapsulated magnetic microparticle or microsphere has a diameter of about 0.5 microns to about 10 microns.

22. The electrolytic ceU of claim 13 wherein said coated electrode is exposed to an external magnetic field.

23. The electrolytic ceU of claim 13 wherein said binding agent comprises at least one polymer.

24. The electrolytic ceU of claim 23 wherein said polymer is polystyrene.

25. The electrolytic ceU of claim 23 wherein said polymer is polyvinylpropyhne.

26. The electrolytic ceU of claim 23 wherein said polymer is a perfluorinated polymer.

27. The electrolytic ceU of claim 23 wherein said polymer is a conducting polymer.

28. The electrolytic ceU of claim 23 wherein said polymer is polytetrafluoroethylene.

29. The electrolytic ceU of claim 23 wherein said polymer is a co-polymer.

30. The electrolytic ceU of claim 23 wherein said polymer is a polymer composite.

31. The electrolytic ceU of claim 13 wherein said binding agent comprises glass.

32. The electrolytic ceU of claim 13 wherein said binding agent comprises at least one sol-gel material.

33. The electrolytic ceU of claim 13 wherein said binding agent comprises at least one high- temperature ceramic.

34. The electrolytic ceU of claim 13 wherein said binding agent comprises at least one metal.

1938104 - 20

35. The electrolytic ceU of claim 13 wherein said at least one encapsulated magnetic microparticle is a silane encapsulated microparticle.

36. The electrolytic ceU of claim 13 wherein said encapsulated magnetic microparticle comprises at least one substance selected from a group consisting of magnetite, samarium cobalt, neodymium iron boron, an iron based magnet, a magnet semi-conducting material, a molecular magnet and ferro fluids.

37. The electrolytic ceU of claim 1 wherein said at least one electrode is formed by exposing the electrode to an external magnetic force.

38. The electrolytic ceU of claim 13 wherein said encapsulated microparticle or microsphere is formed by coating an encapsulating material onto a surface of said microparticle or microsphere, wherein said encapsulating material is impermeable to gases and ions.

39. The electrolytic ceU of claim 38 wherein said encapsulating material comprises at least one polymer.

40. The electrolytic ceU of claim 39 wherein said polymer is polystyrene.

41. The electrolytic ceU of claim 39 wherein said polymer is polyvinylpropyhne.

42. The electrolytic ceU of claim 39 wherein said polymer is a perfluorinated polymer.

43. The electrolytic ceU of claim 39 wherein said polymer is a conducting polymer.

44. The electrolytic ceU of claim 39 wherein said polymer is polytetrafluoroethylene.

45. The electrolytic ceU of claim 39 wherein said polymer is a co-polymer.

46. The electrolytic ceU of claim 39 wherein said polymer is a composite polymer.

47. The electrolytic ceU of claim 38 wherein said encapsulating material comprises glass.

48. The electrolytic ceU of claim 38 wherein said encapsulating material comprises at least one sol-gel material.

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49. The electrolytic ceU of claim 38 wherein said encapsulating material comprises at least one high-temperature ceramic.

50. The electrolytic ceU of claim 38 wherein said encapsulating material comprises at least one metal.

51. The electrolytic ceU of claim 38 wherein said at least one encapsulated magnetic microparticle is a silane encapsulated microparticle.

52. An electrolytic ceU for producing a chlor-alkah comprising at least two electrodes in reactive contact with an aqueous hquid containing a chloride salt, wherein at least one of the electrodes is within a magnetic field and formed by applying a magnetic coating onto the surface of the electrode to aid in producing the chlor-alkah.

53. An electrolytic ceU for producing a chlor-alkah comprising at least two electrodes in reactive contact with an aqueous hquid containing a chloride salt, wherein at least one of the electrodes is within a magnetic field and formed by applying a magnetic coating onto the surface of the electrode to aid in producing the chlor-alkah, wherein said magnetic coating comprises at least one encapsulated magnetic microparticle or microsphere, a binding agent and a catalyst.

54. A method for producing a chlor-alkah from an aqueous hquid containing a chloride salt, comprising inducing an electrolytic reaction between at least two electrodes in reactive contact with the aqueous hquid, at least one of said electrodes being within a magnetic field to aid in producing the chlor-alkah.

55. The method of claim 54 wherein said chlor-alkah is chlorine gas.

56. The method of claim 54 wherein said chlor-alkah is hydrogen gas.

57. The method of claim 54 wherein said chlor-alkah is sodium hydroxide.

58. The method of claim 54 wherein said chlor-alkah is a chlorate.

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59. The method of claim 54 wherein said chlor-alkah is a chlorite.

60. The method of claim 54 wherein said chlor-alkah is a perchlorate.

61. The method of claim 54 wherein said chlor-alkah is potassium hydroxide.

62. The method of claim 54 wherein said chlor-alkah is a hypochlorite.

63. The method of claim 54 further comprising purifying said aqueous hquid prior to the electrolytic reaction.

64. The method of claim 54 further comprising evaporating said aqueous hquid prior to the electrolytic reaction.

65. The method of claim 54 wherein said electrode is a platinum working cathode.

66. The method of claim 54 wherein said electrode is a carbon working anode.

67. The method of claim 54 wherein at least one of said electrodes that is within a magnetic field has a magnetic coating thereon.

68. The method of claim 67 wherein said magnetic coating comprises at least one encapsulated magnetic microparticle or microsphere, a binding agent and a catalyst.

69. The method of claim 68 wherein said magnetic coating comprises about 10% to about 20% said encapsulated magnetic microparticle or microsphere, about 10% to about 20% said at least one catalyst and about 65% to about 75% said at least one binding agent.

70. The method of claim 68 wherein the electrode that has a magnetic coating is a platinum working cathode.

71. The method of claim 68 wherein the electrode that has a magnetic coating is a carbon working anode.

72. The method of claim 68 wherein said catalyst is carbon black.

73. The method of claim 68 wherein said catalyst is ruthenium black.

74. The method of claim 68 wherein said catalyst is platinum black.

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75. The method of claim 68 wherein said catalyst is platinized carbon.

76. The method of claim 68 wherein said catalyst is a magnetocatalyst.

77. The method of claim 68 wherein said catalyst is a metal or metal oxide.

78. The method of claim 68 wherein said magnetic microparticle or microsphere has a diameter of about 0.5 microns to about 12 microns.

79. The method of claim 68 wherein the electrode that has a magnetic coating is exposed to an external magnetic field during the electrolytic reaction.

80. The method of claim 68 wherein said binding agent comprises at least one polymer.

81. The method of claim 80 wherein said polymer is polystyrene.

82. The method of claim 80 wherein said polymer is polyvinylpropyhne.

83. The method of claim 80 wherein said polymer is a perfluorinated polymer.

84. The method of claim 80 wherein said polymer is a conducting polymer.

85. The method of claim 80 wherein said polymer is polytetrafluoroethylene.

86. The method of claim 80 wherein said polymer is a co-polymer.

87. The method of claim 80 wherein said polymer is a composite polymer.

88. The method of claim 68 wherein said binding agent comprises glass.

89. The method of claim 68 wherein said binding agent comprises at least one sol-gel material.

90. The method of claim 68 wherein said binding agent comprises at least one high- temperature ceramic.

91. The method of claim 68 wherein said binding agent comprises at least one metal.

92. The method of claim 68 wherein said at least one encapsulated magnetic microparticle or microsphere is a silane encapsulated microparticle.

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93. The method of claim 68 wherein said encapsulated magnetic microparticle or microsphere comprises at least one substance selected from a group consisting of magnetite, samarium cobalt, neodymium iron boron, an iron based magnet, a magnet semi-conducting material, a molecular magnet and ferro fluids.

94. The method of claim 54 wherein at least one of said electrodes that is within a magnetic field is formed by exposing the electrode to an external magnetic force.

95. The method of claim 54 wherein at least one of said electrodes is formed by coating at least one encapsulated magnetic microparticle or microsphere onto the electrode that is within a magnetic field, wherein said microparticle is coated with a catalyst.

96. The method of claim 95 wherein at least one of said electrodes is a platinum working cathode.

97. The method of claim 95 wherein at least one of said electrode is a carbon working anode.

98. The method of claim 95 wherein said catalyst is carbon black.

99. The method of claim 95 wherein said catalyst is ruthenium black.

100. The method of claim 95 wherein said catalyst is a metal or metal oxide.

101. The method of claim 95 wherein said catalyst is a magnetocatalyst.

102. The method of claim 95 wherein said catalyst is platinum black.

103. The method of claim 95 wherein said catalyst is platinized carbon.

104. The method of claim 95 wherein said encapsulated magnetic microparticle or microsphere has a diameter of about 0.5 microns to about 10 microns.

105. The method of claim 95 wherein the electrode that has a magnetic coating is exposed to an external magnetic field during the electrolytic reaction.

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106. The method of claim 95 wherein said encapsulated microparticle or microsphere is formed by coating an encapsulating material onto a surface of said microparticle or microsphere, wherein said encapsulating material is impermeable to gases and ions.

107. The method of claim 106 wherein said encapsulating material comprises at least one polymer.

108. The method of claim 107 wherein said polymer is polystyrene.

109. The method of claim 107 wherein said polymer is polyvinylpropyhne.

110. The method of claim 107 wherein said polymer is a perfluorinated polymer.

111. The method of claim 107 wherein said polymer is a conducting polymer.

112. The method of claim 107 wherein said polymer is polytetrafluoroethylene.

113. The method of claim 107 wherein said polymer is a co-polymer.

114. The method of claim 107 wherein said polymer is a composite polymer.

115. The method of claim 106 wherein said encapsulating material comprises glass.

116. The method of claim 106 wherein said encapsulating material comprises at least one sol- gel material.

117. The method of claim 106 wherein said encapsulating material comprises at least one high-temperature ceramic.

118. The method of claim 106 wherein said encapsulating material comprises at least one metal.

119. The method of claim 95 wherein said at least one encapsulated magnetic microparticle is a silane encapsulated microparticle.

120. The method of claim 54 wherein said at least one of said electrode is in reactive contact with at least one catalyst.

121. The method of claim 120 wherein said catalyst is a magnetocatalyst.

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122. The method of claim 120 wherein said catalyst is metal or metal oxide.

123. The method of claim 120 wherein said catalyst is platinum black.

124. The method of claim 120 wherein said catalyst is platinized carbon.

125. The method of claim 120 wherein said electrode is a platinum working cathode.

126. The method of claim 120 wherein said electrode is a carbon working anode.

127. The method of claim 120 wherein said catalyst is carbon black.

128. The method of claim 120 wherein said catalyst is ruthenium black.

129. The method of claim 54 wherein the electrode that is within a magnetic field is coated with a magnetic catalyst.

130. The method of claim 129 wherein said magnetic catalyst is a lanthanide-based semiconducting catalyst.

131. The method of claim 129 wherein said magnetic catalyst is nickel.

132. The method of claim 129 wherein said magnetic catalyst is cobalt.

133. The method of claim 54 wherein the electrode that is within the magnetic field is coated with a magnetic binding agent.

134. A method for producing a chlor-alkah from an aqueous hquid containing a chloride salt, comprising inducing an electrolytic reaction between at least two electrodes in reactive contact with the aqueous hquid, wherein at least one of said electrodes is within a magnetic field and formed by applying a magnetic coating onto the surface of the electrode to aid in producing the chlor-alkah.

135. A method for producing a chlor-alkah from an aqueous hquid containing a chloride salt, comprising inducing an electrolytic reaction between at least two electrodes in reactive contact with the aqueous hquid, wherein at least one of said electrodes is within a magnetic field and formed by applying a magnetic coating onto the surface of the electrode to aid in producing the

1938104 - 27 - chlor-alkah, wherein said magnetic coating comprises at least one encapsulated magnetic microparticle or microsphere, a binding agent and a catalyst.

136. A chlor-alkah produced by the method of claim 54.

137. A chlor-alkah produced by the method of claim 68.

138. A chlor-alkali produced by the method of claim 95.

139. A chlor-alkah produced by the method of claim 120.

140. A chlor-alkah produced by the method of claim 133.

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