Patent Application
20130233722
The priority of U.S. Application Ser. No. 61/608,583, entitled, “An Electrochemical Process for Direct one step conversion of methane to Ethylene on a Three Phase Gas, Liquid, Solid Interface”, and filed Mar. 8, 2012, in the name of the inventor Ed Chen is hereby claimed pursuant to 35 U.S.C. §119(e). This application is commonly assigned herewith and is also hereby incorporated for all purposes as if set forth verbatim herein.
The priority of U.S. Application Ser. No. 61/713,487, entitled, “A Process for Electrochemical Fischer Trospch”, filed Oct. 13, 2012, in the name of the inventor Ed Chen is hereby claimed pursuant to 35 U.S.C. §119(e). This application is commonly assigned herewith and is also hereby incorporated for all purposes as if set forth verbatim herein.
Not applicable.
Not applicable.
This section of this document introduces information about and/or from the art that may provide context for or be related to the subject matter described herein and/or claimed below. It provides background information to facilitate a better understanding of the various aspects of the claimed subject matter. This is therefore a discussion of “related” art. That such art is related in no way implies that it is also “prior” art. The related art may or may not be prior art. The discussion in this section of this document is to be read in this light, and not as admissions of prior art.
Prior art commercial processes for converting methane to other hydrocarbons, for example; sometimes include a partial oxidation process that is highly energy intensive and operates under high pressures and temperatures. The actual syngas cleanup step occurs after the syngas has been cooled. Tar, oils, phenols, ammonia and water co-products are condensed from the gas stream and purified and sent on. The gas moves to a cleaning area where further impurities are removed and finally carbon dioxide is removed. The syngas is then passed under high pressures (30 bars) with some more recent “low pressure” processes operating at slightly above 10 bars at approximately 200-400 degrees Celsius to form hydrocarbons, oxygenates, and other carbon and hydrogen based species. The high pressure reactions utilize iron or nickel as their catalysts, while low pressure synthesis often uses cobalt. These processes use solid electrolytes rather than aqueous electrolytes.
Another problem with methane activation is catalyst deactivation and regeneration, temperature control, and high pressures. Catalysts are often deactivated when the surface is covered by waxes and coke (carbon black). The high temperatures also produce undesirable products such as wax which tends to deactivate the catalyst. Finally, water is also a byproduct of this reaction.
The art therefore possesses a number of methane activation processes that, even if satisfactory in some respects, have several drawbacks. The art furthermore is always receptive to improvements or alternative means, methods and configurations. Therefore the art will well receive the technique described herein.
In a first aspect, a method for chain modification of hydrocarbons and organic compounds comprises: contacting an aqueous electrolyte, a powered electrode including a catalyst, and a gaseous methane feedstock in a reaction area; and activating the methane in an aqueous electrochemical reaction to generate methyl radicals at the powered electrode and yield a long chained hydrocarbon.
In a second aspect, method for chain modification of hydrocarbons and organic compounds comprises: contacting an aqueous electrolyte with a catalyst in a reaction area; introducing a gaseous methane feedstock directly into the reaction area under pressure; and reacting the aqueous electrolyte, the catalyst, and the gaseous methane feedstock at temperatures in the range of −10 C to 900 C and at pressures in the range of 0.1 ATM to 100 ATM.
The above presents a simplified summary of the presently disclosed subject matter m order to provide a basic understanding of some aspects thereof. The summary is not an exhaustive overview, nor is it intended to identify key or critical elements to delineate the scope of the subject matter claimed below. Its sole purpose is to present some concepts in a simplified form as a prelude to the more detailed description set forth below.
The claimed subject matter may be better understood by reference to the following description taken in conjunction with the accompanying drawings, in which like reference numerals identify like elements and in which;
FIG. 5A-FIG.-5B depicts a gas diffusion electrode as may be used in some embodiments.
While the invention is susceptible to various modifications and alternative forms, the drawings illustrate specific embodiments herein described in detail by way of example. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.
Illustrative embodiments of the subject matter claimed below will now be disclosed. In the interest of clarity, not all features of an actual implementation are described in this specification. It will be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort, even if complex and time-consuming, would be a routine undertaking tor those of ordinary skill in the art having the benefit of this disclosure.
The presently disclosed technique is a process for converting gaseous hydrocarbons to longer chained liquid hydrocarbons, longer chained gaseous hydrocarbons, branched-chain liquid hydrocarbons, branched-chain gaseous hydrocarbons, as well as chained and branched-chain organic compounds. In general, the method is for chain modification of hydrocarbons and organic compounds, including chain lengthening. This process more particularly uses aqueous electrolytes to act as a reducing atmosphere and hydrogen and oxygen source for hydrocarbon gases. The process in the disclosed technique is Aqueous Electrochemical Activation of Methane (AEAM) on three phase interface of gas-liquid-solid electrode. AEAM directly turns natural gas and other sources of methane (CH4) into C2+ hydrocarbons and other organic compounds. One exemplary product is ethylene (C2H4) and alcohols such as methanol, ethanol, propanol, and/or butanol.
The reaction of hydrocarbon gases may be successfully achieved with an aqueous electrochemical solution serving as a liquid ion source along with the supply for hydrogen or singlet oxygen being provided by the aqueous electrolyte through acids and/or bases of the aqueous electrolyte. The gaseous hydrocarbon is balanced with the aqueous electrolyte at a solid phase thin film catalyst which is connected to the reaction electrode of an electrolytic cell. The reaction may also be adjusted with different pHs or any kind of additive in the electrolytic solution.
The reaction works by utilizing a 3 phase interface which defines a reaction area. A catalyst, a liquid, and a gas a positioned in the same location and an electric potential is applied to make electrons available to the reaction site. When methane is used as the gas it is possible to create methane radicals which then join with other molecules or parts of molecules or themselves to create longer chained hydrocarbons and/or organic molecules. The reaction site can also cause branched chain production by reacting with a newly created molecule and building on that or continuous chain building. Thus from the simple molecule of methane, CH4, chains of molecules can be built. Existing chained molecules can be lengthened, and existing chained molecules can be branched. A simple example is methane (CH4) can be converted to methanol, CH3(OH). Different voltages create different reaction product distributions or facilitate different reaction types.
This aqueous electrochemical reaction includes a reaction that proceeds at room temperature and pressure, although higher temperatures and pressures may be used. In general, temperatures may range from −10C to 240C, or from −10C to 1000C, and pressures may range from 0.1 ATM to 10 ATM, or from 0.1 ATM to 100 ATM. The process generates reactive methyl radicals through the reaction on the reaction electrodes. On the reaction electrode, the production of methyl radicals occurs.
In at least some embodiments, the reactants need no pre-treatment. Typically methanol from methane must first go through steam reforming to produce syngas (CO and H2). The presently disclosed technique can perform the production of methanol without reforming to produce syngas. Similarly, as described further below, the gaseous methane feedstock may be introduced “directly” into the chamber of an electrochemical cell.
In general, the method introduces a liquid ion source into a first chamber into contact with a catalyst supporting reaction electrode while a counter electrode is disposed in the liquid ion source. The reaction electrode is powered. A gaseous methane feedstock is then introduced directly into a second chamber under enough pressure to overcome the gravitational pressure of the column of electrolyte, which depends on the height of the water, to induce a reaction among the liquid ion source, the catalyst, and the gaseous methane feedstock when the electrodes are powered.
In the embodiments illustrated herein, the technique employs an electrochemical ceil such as the one illustrated in
There is also a second chamber 125 into which a gaseous methane feedstock 130 is introduced as described below. The two chambers are joined by apertures 135 through the wall 140 separating the two chambers 110, 125. The reactor 105 may be constructed in conventional fashion except as noted herein. For example, materials selection, fabrication techniques, and assembly processes in light of the operational parameters disclosed herein will be readily ascertainable to those skilled in the art.
Catalysts will be implementation specific depending, at least in part, on the implementation of the reaction electrode 116. Depending on the embodiment, suitable catalysts may include, but are not limited to, nickel, copper, iron, tin, zinc, ruthenium, palladium, rhenium, or any of the other transition or lanthanide metals, or a noble metal such as platinum, palladium, gold, or silver. They may also include products thereof, including for example cuprous chloride or cuprous oxide, other compounds of catalytic metals, as well as organometalic compounds. Exemplary organometallie compounds include, but are not limited to, tetraearhonyl nickel, lithiumdiphenylcuprate, pentamesitylpentacopper, and etharatedimer.
The electrolyte 120 will also be implementation specific depending, at least in part, on the implementation of the reaction electrode 116. Exemplary liquid ionic substances include, but are not limited to, Alkali or alkaline Earth salts, such as halides, sulfates, sulfites, carbonates, nitrates, or nitrites. The electrolyte 120 may therefore be, depending upon the embodiment, magnesium sulfate (MgS), sodium chloride (NaCl), sulfuric acid (H2SO4), potassium chloride (KCl), hydrogen chloride (HCl), hydrogen bromide (HBr), hydrogen fluoride (HF), potassium chloride (KCl), potassium bromide (KBr), and potassium iodide (KI), or any other suitable electrolyte and acid or base known to the art.
The pH of the electrolyte 120 may range from 0 to 3 and concentrations of between 0.1 M and 3 M may be used. Some embodiments may use water to control pH and concentration, and such water may be industrial grade water, brine, sea water, or even tap water. The liquid ion source, or electrolyte 120, may comprise essentially any liquid ionic substance. In some embodiments, the electrolyte 120 is a halide to benefit catalyst lifetime.
In addition to the reactor 105, the electrochemical cell 100 includes a gas source 145 and a power source 150, and an electrolyte source 163. The gas source 145 provides the gaseous methane feedstock 130 while the power source 150 is powering the electrodes 115, 116 under enough pressure to balance and overcome the gravitational pressure of the column of electrolyte, which depends on the height of the water, sufficient to maintain the reaction at the three phase interface 155. The three phase interface 155 defines a reaction area. In some embodiments, this pressure might be, for example, 10000 pascals, or from 0.1 ATM to 10 ATM, or from 0.1 ATM to 100 ATM. The electrolyte source 163 provides adequate levels of the electrolyte 120 to ensure proper operations. The three phases at the interface 155 are the liquid electrolyte 120, the solid catalyst of the reaction electrode 116, and the gaseous methane feedstock 130. The product 160 is collected in a vessel 165 of some kind in any suitable manner known to the art.
The embodiment of
Those in the art will appreciate that some implementation specific details are omitted from
The reaction is conceptually illustrated in
Still further, very little catalyst deactivation occurs in some embodiments because the catalyst is protected by a layer of chloride, which also acts as an absorbent for the reactants, and the electrolyte is saturated with Cl− preventing typical catalyst poisons from bonding with the catalyst and deactivating it, as this would force the release of a Cl−ion into the liquid. In addition, this process further prevents the deposition of impurities in water, which could deactivate the catalyst. These aspects will be explored further below.
Returning now to
The presently disclosed technique admits variation in the implementation of the electrode at which the reaction occurs, hereafter referred to as the “reaction electrode”. The other electrode will be referred to as the “counter electrode”. In the embodiment of
One such modification is that the copper mesh used in the illustrated embodiment is an 80 mesh rather than a 40 mesh. This mesh may be plated with high current densities to produce fractal foam structures with high surface areas which may be utilized as catalysts in this reaction.
More particularly, the catalyst 305 is supported on a copper mesh 310 embedded In an ion exchange resin 300 as shown in
The copper wire mesh 310 can be used to structure the catalyst 305 within the resin 300. The assembly 315 containing the catalyst 305 can be deposited onto or otherwise structurally associated with a hydrophilic paper 320, as shown in
The counter electrode 115, the reaction electrode 116 is disposed within a reactor 105 so that, in use, it is submerged in the electrolyte 120 and the catalyst 305 forms one part of the three-phase interface 155. When electricity is applied to electrodes 115, 116, electrochemical reduction discussed above takes place to produce hydrocarbons and organic chemicals. The reaction electrode 320 receives the electrical power and catalyzes a reaction between the hydrogen in the electrolyte 120 and the gaseous methane feedstock 130.
As mentioned above, the copper mesh 310 in the illustrated embodiment is an mesh in the range of 1-400 mesh.
In a second embodiment shown in
This material is then mixed with a hydrophilic binding agent (not shown), such as polyvinyl alcohol (PVA), polyvinyl acetate (PVAc), or Nafion. An ink is made from the mixture of impregnated graphite, binding agent, and alcohol or other organic solvent. The ink is painted onto the hydrophobic layer 405 and then bonded through any means, such as atmospheric drying, heat press, or other means of application of heat.
The copper 420 impregnated into the ion electrode 400 is then made into a cuprous halide through any suitable procedure. One embodiment of the procedure to make the cuprous halide is to submerge the electrode in a solution of hydrochloric acid and cupric chloride, heat to 100° C. for 2 hours. Another embodiment submerges the impregnated electrode 400 in 3 M KBr or 3 M KI and run a 4 V pulse of electricity to the electrode 400 in order to form a thin film of cuprous halide 425, shown in cross-section
In another embodiment, the copper particles in the electrode are first plated with silver by electroless plating or another method, creating a thin film of silver over the copper. Copper may then be plated onto the silver and transformed into a halide through procedure previously described. In another embodiment, silver particles are deposited into the hydrophilic layer, coated with copper electrolytically, and then the same procedure for the conversion of the copper layer to a copper halide layer is conducted.
In another embodiment, the gas diffusion electrode uses nanoparticles reduced from a solution of Cupric Chloride with an excess of ascorbic acid and 10 grams of carbon graphite. The amalgam was heated to 100° C. for eight hours. It is then mixed with equal amounts in weight of a hydrophilic binder.
In another embodiment, a high mesh copper of 200 mesh is allowed to form cuprous chloride in a solution of cupric chloride and hydrochloric acid. This layer of halide on the surface of the catalyst material allows for catalyst regeneration. This accounts for the abnormally high lifetime of the three phase reaction. The result is then treated in a 1 M solution of Cupric Chloride heated to 100° C.
The electrode 400 therefore includes a covering or coating 425 of cuprous chloride to prevent “poisoning” or fouling of the electrode 400 during operation. The electrodes in this embodiment must be copper so that no other metals foul the reaction by creating intermediate products which ruin the efficacy of the surface of the copper. Some embodiments also treat the copper with a high surface area powder by electroplating, which will allow for the generation of greater microturbulence, thereby creating more contact and release between the three phase reaction surface. Furthermore, contrary to conventional practice, rather than separate the cathode and anode, the cathode and anode are allowed to remain in the same electrolyte in this embodiment. (The electrolyte is filtered through a pump not shown.) The electrolyte is therefore contacted directly to the gas diffusion electrode 400 rather than through the intercession of a polymer exchange membrane.
Catalysts in this particular embodiment may include copper, silver, gold, iron, tin, zinc, ruthenium, platinum, palladium, rhenium, or any of the other transition or lanthanide metals. In addition, the catalysts may be formed into a metal foam or alternatively it may be deposited through electroless or electrolytic deposition onto a porous support with a hydrophobic and hydrophilic layer.
In electrochemical systems, it is often difficult to make a good electrical contact between gas diffusion medium and the current collector. The need for a solid polymer electrolyte to some degree is the first order solution to the problem at hand. Carbon paper has a significant resistance across of up to 2Ω that impedes the effective application of gas diffusion electrodes to electrochemical applications. By pressing a wire made from a metal such as nickel, copper, iron, steel, or a noble metal such as platinum, gold, or silver directly into the carbon paper, gas diffusion media may be extended into applications such as hydrocarbon processing and fuel cell applications. The production of such papers is relatively straight forward though requires a few enabling aspects for it to work. A small amount of adhesive material is mixed in with activated carbon particles with a high internal porosity, for example a BET of 50 m2/gram. This serves as the binder which may be applied between existing conductive gas diffusion medium such as a carbon paper, a toray paper, or other conductive gas diffusion electrodes.
The binder slurry both binds the metal of the wire mesh 505 to the surface of the conductive paper 510, while providing conductivity itself and holds the wire mesh 505 firm against the conductive paper 510, which overcomes the contact resistance. The surface of the wire mesh 505 is cleaned with a solvent before being applied to the carbon paper 510 to remove any oils from the surface of the contact region, as this may cause unwanted resistance to build up. The wire should be thick enough that the wire mesh 505 forms a slight indentation into the paper 510 as to provide maximum contact area.
In another embodiment 500′, the production of the paper 510 is conducted and deposited directly onto the wire mesh 505, the result of which is shown in
The technique illustrated in
In one particular embodiment, the electrodes are electrically short circuited within the electrolyte while maintaining a three phase interface.
So, turning now to the process again and referring to
The method of operation generally comprises introducing the electrolyte 120 into the first chamber 110 into direct contact with the powered electrode surfaces 115 and 116. The gaseous methane feedstock 130 is then introduced into the second chamber 125 under enough pressure to over come the gravitational pressure of the column of electrolyte, which depends on the height of the water, to induce the reaction. During the reaction, the electrolyte 120 is filtered, the gaseous methane feedstock 130 is maintained at a selected pressure to ensure its presence at the three phase interface 155, and the product 165 is collected. Within this general context, the following examples are implemented.
Above the second chamber 125, but attached to it, is an area for the introduction of a cathode reaction electrode 116 where the three-phase interface 155 will form. Catalysts supported by the reaction electrode 116 include copper, silver, gold, iron, tin, zinc, ruthenium, platinum, palladium, rhenium, or any of the other transition or lanthanide metals. In addition, the catalysts may be formed into a metal foam or alternatively it may be deposited through electroless or electrytic deposition onto a porous support with a hydrophobic and hydrophilic layer as previously described above. The electrolyte 120 may comprise, for example, potassium chloride (KCl), potassium bromide (KBr), potassium iodide (KI), or any other suitable electrolyte known to the art.
This particular embodiment implements the reaction electrode 116 as the gas diffusion electrode described above with the cuprous halide coating. Alternative embodiments may use another cuprous halide coating the surface of the metal. Cuprous Oxide, Cupric Oxide, and other varying valence states of copper will also work in the reaction.
By maintaining a three phase interface between gaseous methane feedstock 130 and the electrolyte 120, the methane will form organic chemicals and form a nearly complete conversion when there is continuous contact to the gaseous methane feedstock 130 on the three phase interface 155 between the liquid electrolyte 120, the solid catalyst, and the gaseous methane feedstock 130. Another means of maintaining the three phase interface is to use a separation membrane which selectively allows hydrogen and water to penetrate. One such membrane is Nafion. Another means is to use a fuel cell type set up but instead of generating a current, a current is introduced to generate a chemical.
Other reaction mechanism also produces organic compounds such as ethers, epoxides, and alcohols, among other compounds.
The electrolyte 120 should be relatively concentrated at 0.1 M-3 M and should be a halide electrolytes discussed above to increase catalyst lifetime. The higher the surface area between the reaction electrode 116 and the gaseous chamber 125 on one side and the liquid electrolyte 120 on the other side, the higher the conversion rates. Operating pressures could be ranged from only 10000 pascals, or from 0.1 atm to 100 atm, or from 0.1 atm to 100 atm, though Standard Temperature and Pressures (STP) were sufficient for the reaction.
In one embodiment of the gas diffusion electrode (GDE) an antioxidant layer of ascorbic acid is mixed with the GDE high porosity carbon. The high porosity carbon includes nanotubes, fullerines, and other specialized formations of carbon as described above. The high porosity carbon is impregnated through reduction of cupric chloride, or other form of carbon. It is then made into a halide by treatment with a chloride solution under the proper pH and temperature of EMF conditions. It also includes a reaction in the solid polymer phase. A paste is made from the impregnated carbon, ascorbic acid, and a hydrophilic binding agent. This paste is painted onto a hydrophobic layer. Some embodiments include antioxidants in the layer as described above.
Note that not all embodiments will manifest ail these characteristics and, to the extent they do, they will not necessarily manifest them to the same extent. Thus, some embodiments may omit one or more of these characteristics entirely. Furthermore, some embodiments may exhibit other characteristics in addition to, or in lieu of, those described herein.
The phrase “capable of” as used herein is a recognition of the fact that some functions described for the various parts of the disclosed apparatus are performed only when the apparatus is powered and/or in operation. Those in the art having the benefit of this disclosure will appreciate that the embodiments illustrated herein include a number of electronic or electro-mechanical parts that, to operate, require electrical power. Even when provided with power, some functions described herein only occur when in operation. Thus, at times, some embodiments of the apparatus of the invention are “capable of” performing the recited functions even when they are not actually performing them—i.e., when there is no power or when they are powered but not in operation.
The following patent, applications, and publications are hereby incorporated by reference for all purposes as if set forth verbatim herein:
U.S. Application Ser. No. 61/608,583, entitled, “An Electrochemical Process for Direct one step conversion of methane to Ethylene on a Three Phase Gas, Liquid, Solid Interface,” and filed Mar. 8, 2012, in the name of the inventor Ed Chen and commonly assigned herewith.
U.S. Application Ser. No. 61/713,487, entitled, “A Process for Electrochemical Fischer Trospch,” filed Oct. 13, 2012, in the name of the inventor Ed Chen and commonly assigned herewith.
To the extent that any patent, patent application, or other reference incorporated herein by reference conflicts with the present disclosure set forth herein, the present disclosure controls.
This concludes the detailed description. The particular embodiments disclosed above are illustrative only, as the invention may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the invention. Accordingly, the protection sought herein is as set forth in the claims below.
| Number | Date | Country | |
|---|---|---|---|
| 61608583 | Mar 2012 | US | |
| 61713487 | Oct 2012 | US |
