ELECTROCHEMICAL DEVICE FOR PRODUCING HYDROGEN
The present invention provides an electrolytic device and apparatus comprising the same, where the electrolytic device includes a means for generating a first gas stream that is enriched with a first gas. In particular, the electrolytic device of the invention comprises a first tubular electrode and a second tubular electrode that is coaxially located within the first tubular electrode. The second tubular electrode comprises a plurality of orifices that is adapted to producing a first gas stream that is enriched with a first gas.
The present invention relates to an electrolytic device and apparatus comprising the same, where the electrolytic device comprises a first tubular electrode and a second tubular electrode that is coaxially located within the first tubular electrode. The second tubular electrode comprises a plurality of orifices that is adapted to producing a first gas stream that is enriched with a first gas.
BACKGROUND OF THE INVENTIONElectrolysis has been utilized in many forms for producing gases from a liquid solution. Most electrolysis methods use a flat plate system. All electrolytic devices produce both oxygen and hydrogen gases from an aqueous electrolyte solution in substantially a theoretical mixture amount, i.e., 66⅔% hydrogen and 33⅓% oxygen. If a concentrated oxygen or hydrogen gas is desired, it must be separated from one another. While a wide variety of methods are known to one skilled in the art for separating gases, typically separation of gases in electrolytic devices is achieved using a gas permeable membrane. Gas permeable membranes allow one type of gas (e.g., hydrogen) to pass through the membrane while preventing the other gas (e.g., oxygen) from passing through. These gas permeable membranes typically achieve separation of gases based on the molecular size of gases.
Use of a gas permeable membrane adds to the complexity of the electrolytic devices as well as the overall cost of the electrolytic devices. For example, certain gas permeable membranes may not be compatible with a strongly basic or acidic electrolyte solution, thereby requiring a particular electrolyte solution to be used within the electrolyte device. Currently, no electrolytic device is known that can separate gases without the use of a gas permeable membrane or some other mechanical means.
Therefore, there is a need for an electrolytic device that can produce hydrogen enriched gas from an aqueous solution without a need for a gas permeable membrane or other gas separation processes.
SUMMARY OF THE INVENTIONThe present inventors have discovered that by providing a plurality of orifices within a certain electrode in a tube-in-tube electrolytic device affords separation of gases without a need for a gas permeable membrane or other gas separation means currently utilized in conventional electrolytic gas production devices and methods.
Accordingly, some aspects of the invention provide an electrochemical device adapted for producing a gas stream enriched with a first gas using electrolytic decomposition of a fluid. In some embodiments, devices of the invention include:
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- a first tubular electrode; and
- a second tubular electrode located within the interior space of said first tubular electrode,
wherein - one of said first or said second tubular electrode is configured as a cathode and the other is configured as an anode;
- the inner cross-sectional area of said first tubular electrode is greater than the outer cross-sectional area of said second tubular electrode; and
- said second tubular electrode comprises a plurality of orifices along its length, wherein said plurality of orifices is adapted for producing a first gas stream that is enriched with a first gas within the inner space or the external space of said second tubular electrode.
In some embodiments, said plurality of orifices is adapted to produce the first gas stream that is enriched with said first gas within the inner space or exterior of said second tubular electrode.
Yet in other embodiments, said plurality of orifices is adapted to produce said first gas stream within the inner space of said second tubular electrode.
Still in other embodiments, said device is adapted to produce said first gas stream within the exterior space of said second tubular electrode.
In other embodiments, the electrochemical device further comprises a first gas outlet adapted to allow said first gas stream to be obtained through said first gas outlet. Within these embodiments, in some instances said first gas outlet is operative connected to the inner space of said second tubular electrode. Still in other instances, said first gas outlet is operative connected to the external space of said second tubular electrode.
Still yet in other embodiments, said electrochemical device is further adapted to produce a second gas stream that is enriched with a second gas from the fluid.
Yet still in other embodiments, said electrochemical device further comprises a second gas outlet that is adapted to allow said second gas stream to be obtained through said second gas outlet. Within these embodiments, in some instances said device is adapted to produce said first or said second gas stream within the inner space of said second tubular electrode and to produce the other gas stream within the exterior space of said second tubular electrode.
Another aspect of the invention provides an electrochemical device for producing hydrogen from an aqueous electrolyte solution, said device comprising:
-
- a first tubular electrode; and
- a second tubular electrode located within the interior space of said first tubular electrode and arranged coaxially relative to said first tubular electrode,
wherein - one of said first or said second tubular electrode is configured as a cathode and the other is configured as an anode;
- the inner cross-sectional area of said first tubular electrode is greater than the outer cross-sectional area of said second tubular electrode; and
- said second tubular electrode comprises a plurality of orifices along its length, wherein said plurality of orifices is adapted for producing a hydrogen enriched gas stream within the inner space or the external space of said second tubular electrode.
In some embodiments, said plurality of orifices is adapted to produce a hydrogen gas enriched stream within the inner space of said second tubular electrode. In some instances, said hydrogen enriched gas stream comprises at least 75% hydrogen.
Still in other embodiments, said device is further adapted to produce oxygen enriched gas stream within the exterior surface of said second tubular electrode.
In other embodiments, said device is adapted to produce said hydrogen enriched gas stream within the exterior space of said second tubular electrode.
Yet in other embodiments, the electrochemical device further comprises a gas outlet operatively connected to hydrogen enriched gas stream, wherein said gas outlet is adapted to allow hydrogen enriched gas stream to be obtained through said gas outlet.
In some embodiments, said second tubular electrode is a cathode.
Still in other embodiments, the electrochemical device further comprises an electrolytic aqueous solution having a pH of about 11 or less. In some instances, said electrolytic aqueous solution comprises about 7% or less of KOH by wt.
The present invention will be described with regard to the accompanying drawings which assist in illustrating various features of the invention. In this regard, the present invention generally relates to an electrochemical (i.e., electrolytic) device for producing a gas from a fluid. In particular, the invention relates to an electrolytic device adapted for producing a gas stream enriched with a first gas from electrolytic decomposition of a fluid. As used herein, the term “enriched” means more than the theoretical mixture amount. For example, production of hydrogen and oxygen using an aqueous solution theoretically produces a gas mixture that is 66⅔% hydrogen and 33⅓% oxygen gas. However, devices of the invention produce a gas stream that is adapted to producing a gas stream with a gas mixture that is more than 66⅔% hydrogen. Typically, for production of hydrogen and oxygen using an aqueous solution, devices of the invention are adapted to producing a gas stream that is at least 70%, often at least 75%, more often at least 80%, still more often at least 85%, and most often at least 90% hydrogen. Conversely, the second gas stream will be enriched with oxygen.
One particular embodiment of electrolytic devices of the invention is generally illustrated in
As can be seen in
Referring again to
Referring to
In some instances, as shown in
It should be appreciated that while the electrolytic device of the invention are primarily described as being useful in producing hydrogen gas from an aqueous electrolyte solution, the scope of the invention is not limited to hydrogen gas production. In fact, one skilled in the art having read the present disclosure can readily recognize a numerous applications for which the electrolytic device of the invention can be used. For example, applications for the electrolytic device of the invention include, but are not limited to, producing hydrogen, producing oxygen, producing various other gases and suitable by-product production, electrolysis of other solvents including non-aqueous electrolytic solvents, energy convertor in a fuel cells, capacitors, super capacitors, redox battery, etc.
In some embodiments, the electrolytic device of the invention is a single stage unit. It should also be appreciated that the electrolytic device of the invention can be utilized in any suitable apparatus, in multiple configurations, e.g., in series or parallel or a combination thereof. Such multiple configurations allow for high levels of hydrogen gas to be produced at low power levels.
As can be seen in the accompanying draws, in some embodiments the length of first electrode 100 is smaller than the second electrode 200. As discussed above, the first electrode 100 can be configured as an anode or cathode as long as the second electrode 200 is configured to be a complementary electrode, i.e., when first electrode 100 is cathode, second electrode 200 is anode and when first electrode 100 is anode then second electrode 200 is cathode.
Second electrode 200 has a plurality of orifices that is adapted to allow enrichment of one gas within the inner space of second electrode 200. The presence of gas separating orifices in second electrode 200 eliminates or reduces the need for a separate gas separation means such as a gas separation membrane, etc.
Two or more electrolytic devices of the invention can be used in parallel, series, and any multiple variations thereof. Moreover, one skilled in the art having read the present disclosure can readily recognize various modifications to the designs that can be incorporated to the electrolytic device of the invention. For example, following are some of the changes that can be incorporated to the electrolytic device of the invention: sizes and shapes of tubes; singular and multiple tubular electrodes; different materials for electrodes (e.g., metals, such as iron, copper, zinc, and precious metals such as platinum, gold, silver, as well as metal alloys such as stainless, brass, etc., ceramics, and any other electric conducting material including combination of materials); size and shape of orifices in the second electrode (e.g., holes, slots, and any other cut configurations); electrode configurations; electrode positions (such as distance between the first and the second electrodes); horizontal, vertical or any other angular position of electrodes; placement of filters (or gas permeable or charge transfer membranes), PEM's, and suchlike devices; coating materials for electrodes (e.g., special coating materials, nano, micro, and other electrode coatings); special designs relating to the surfaces of the electrodes (e.g., to increase the surface area); using a tube-like electrodes (e.g., coil or helically shaped electrodes).
It should be appreciated that the voltage, current, frequency, polarity shifting, pulsing and other variation of applying the necessary electricity can be used with electrolytic device of the invention. Typically, one skilled in the art can readily determine a suitable voltage, current, frequency, and other electricity variables for a particular use. Some of the variables, of course will depend on a variety of factors such as the size of the electrodes, the electrolytic solution used, the amount or the rate of hydrogen gas production desired, etc.
One particular use of electrolytic device of the invention will now be described in reference to producing hydrogen from an aqueous electrolytic solution. However, as described above, the utility of the electrolytic device of the invention is not limited to producing hydrogen.
The global demand for energy has steadily been increasing. With finite availability of fossil fuel, and more significantly, damaging effects of fossil fuel on the environment, there is a great demand for developing sustainable, non-fossil based, “green” energy sources for large scale use. Hydrogen gas has been one of the most promising candidates for clean, renewable energy source. There are a wide variety of methods for producing hydrogen, including electrolysis of water. While a number of electrodes and electrolyte materials have been developed and are currently under investigation for electrolysis of water to produce hydrogen, currently no commercially viable electrode design is available for large scale use.
Furthermore, many conventional large scale production of hydrogen by electrolysis use a strongly alkaline solution. Unfortunately, majority of conventional electrolysis to produce hydrogen also requires high powered, high pressure, heavy, oversized apparatus that tend to need heating, cooling, fanning, purging or filtering tools. In other conventional hydrogen production methods through efficient electrolysis involve the use of various strongly corrosive or toxic electrolytes, e.g., KOH, which require proper handling and safety measures. Generally, in conventional large scale use of the electrolysis apparatus, cell leakage and environmental exposure is always a possibility creating risks both to human and environment.
While electrolytic device of the invention can be used with any conventional electrolytic solution known to one skilled in the art as well as any other electrolytic solution that may be developed, in one particular embodiment, the electrolytic device of the invention uses electrolytic solution that is safer than conventional commercial electrolytes. In some instances, the electrolyte solution used with electrolytic device of the invention is non-toxic. In some instances, electrolytic solution used in conjunction with the electrolytic device of the invention contains FDA approved and generally recognized as safe in the levels contained in the electrolytic solution. Moreover, some components of electrolyte solution used are fully biodegradable. Still in other instances, components of electrolyte solution that is used with the electrolytic device of the invention occur in nature and are used at concentrations no higher than what would be found naturally in the environment.
In electrolysis, water is decomposed to hydrogen and oxygen, by passing a current through electrodes in the presence of suitable substances, called electrolytes. Electric current causes positively charged hydrogen ions to migrate to the negatively charged cathode, where a reduction takes place in order to form hydrogen atoms. The atoms formed then combine to form gaseous hydrogen molecules (H2). On the other hand, oxygen is formed at the other electrode (the positively charged anode). The stoichiometry of the reaction is two volumes of hydrogen to one volume of oxygen. One of the important considerations in the construction of electrolysis units is to use adequate electrodes to avoid unwanted reactions, which can produce impurities in the hydrogen gas. Conventional electrolytic cells also use a separating membrane that allows the passage of ions or electrons and not oxygen or hydrogen atoms. As discussed herein, electrolytic device of the invention eliminates or reduces the need for such a separating membrane.
In one particular embodiment, the electrolyte solution used in conjunction with the electrolytic device of the invention include 7% or less of KOH by weight. It should be noted conventional electrolyte solution using KOH has at least 10% or more of KOH, typically about 30% KOH by weight. Such a strongly basic electrolytic solution is caustic, and poses a significant danger to human and environment. In contrast, by using heretofore unheard of low concentration of KOH in electrolyte solution significantly reduces, in fact substantially eliminates, the danger to human and environment due to a possible leakage of electrolyte solution.
In some embodiments, the pH of the electrolyte solution used in conjunction with the electrolytic device of the invention is about pH 11 or less, typically pH 10 or less.
The electrolyte solution of the invention can also include one or more of the following components, all of which are present in concentrations that does not pose danger to human or environment: ascorbic acid; phosphoric acid; citric acid; acetic acid; sorbitol; potassium carbonate; propionic acid; sodium propionate; sucrose; lithium carbonate; lithium citrate; magnesium chloride; sodium teraborate; sodium acetate; and sodium sulphate. Other suitable electrolyte solution is disclosed in a commonly assigned patent application that is filed even date herewith.
In one particular embodiment, the electrolyte solution is prepared by adding 25 g of lithium citrate to 1 L of water. Catalytic promoters can also be added to the electrolyte at this point such as, but is not limited to, at least one component from the list of components provided above or any mixture thereof.
Additional objects, advantages, and novel features of this invention will become apparent to those skilled in the art upon examination of the following examples thereof, which are not intended to be limiting. In the Examples, procedures that are constructively reduced to practice are described in the present tense, and procedures that have been carried out in the laboratory are set forth in the past tense.
ExamplesA device similar to that shown in
Analysis of Gases from Second as Outlet 212
Analysis of Gases from First Gas Outlet 112
As the above results show, electrochemical device of the invention separated hydrogen gas from oxygen gas without a need for a gas permeable membrane or any other gas separation means at a significant hydrogen purity level. The theoretical ratio of H2 to O2 produced in electrolysis of water is 2:1 (i.e., two parts hydrogen gas per one part oxygen gas). However, as can be seen above, electrochemical device of the invention produces a significantly higher ratio of hydrogen gas in the gas outlet 212.
The foregoing discussion of the invention has been presented for purposes of illustration and description. The foregoing is not intended to limit the invention to the form or forms disclosed herein. Although the description of the invention has included description of one or more embodiments and certain variations and modifications, other variations and modifications are within the scope of the invention, e.g., as may be within the skill and knowledge of those in the art, after understanding the present disclosure. It is intended to obtain rights which include alternative embodiments to the extent permitted, including alternate, interchangeable and/or equivalent structures, functions, ranges or steps to those claimed, whether or not such alternate, interchangeable and/or equivalent structures, functions, ranges or steps are disclosed herein, and without intending to publicly dedicate any patentable subject matter.
Claims
1. An electrochemical device adapted for producing gas through electrolytic decomposition of a fluid, said device comprising: wherein
- a first tubular electrode; and
- a second tubular electrode located within the interior space of said first tubular electrode and arranged coaxially relative to said first tubular electrode,
- one of said first or said second tubular electrode is configured as a cathode and the other is configured as an anode;
- the inner cross-sectional area of said first tubular electrode is greater than the outer cross-sectional area of said second tubular electrode; and
- said second tubular electrode comprises a plurality of orifices along its length, wherein said plurality of orifices is adapted for producing a first gas stream that is enriched with a first gas within the inner space or the external space of said second tubular electrode.
2. The electrochemical device of claim 1, wherein said plurality of orifices is adapted to produce the first gas stream that is enriched with said first gas within the inner space or exterior of said second tubular electrode.
3. The electrochemical device of claim 1, wherein said plurality of orifices is adapted to produce said first gas stream within the inner space of said second tubular electrode.
4. The electrochemical device of claim 1, wherein said device is adapted to produce said first gas stream within the exterior space of said second tubular electrode.
5. The electrochemical device of claim 1 further comprising a first gas outlet adapted to allow said first gas stream to be obtained through said first gas outlet.
6. The electrochemical device of claim 5, wherein said first gas outlet is operative connected to the inner space of said second tubular electrode.
7. The electrochemical device of claim 5, wherein said first gas outlet is operative connected to the external space of said second tubular electrode.
8. The electrochemical device of claim 1, wherein said electrochemical device is further adapted to produce a second gas stream that is enriched with a second gas from the fluid.
9. The electrochemical device of claim 8, wherein said electrochemical device further comprises a second gas outlet that is adapted to allow said second gas stream to be obtained through said second gas outlet.
10. The electrochemical device of claim 9, wherein said device is adapted to produce said first or said second gas stream within the inner space of said second tubular electrode and to produce the other gas stream within the exterior space of said second tubular electrode.
11. An electrochemical device for producing hydrogen from an aqueous electrolyte solution, said device comprising: wherein
- a first tubular electrode; and
- a second tubular electrode located within the interior space of said first tubular electrode and arranged coaxially relative to said first tubular electrode,
- one of said first or said second tubular electrode is configured as a cathode and the other is configured as an anode;
- the inner cross-sectional area of said first tubular electrode is greater than the outer cross-sectional area of said second tubular electrode; and
- said second tubular electrode comprises a plurality of orifices along its length, wherein said plurality of orifices is adapted for producing a hydrogen enriched gas stream within the inner space or the external space of said second tubular electrode.
12. The electrochemical device of claim 11, wherein said plurality of orifices is adapted to produce a hydrogen gas enriched stream within the inner space of said second tubular electrode.
13. The electrochemical device of claim 12, wherein said hydrogen enriched gas stream comprises at least 75% hydrogen.
14. The electrochemical device of claim 12, wherein said device is further adapted to produce oxygen enriched gas stream within the exterior surface of said second tubular electrode.
15. The electrochemical device of claim 11, wherein said device is adapted to produce said hydrogen enriched gas stream within the exterior space of said second tubular electrode.
16. The electrochemical device of claim 11 further comprising a gas outlet operatively connected to hydrogen enriched gas stream, wherein said gas outlet is adapted to allow hydrogen enriched gas stream to be obtained through said gas outlet.
17. The electrochemical device of claim 11, wherein said second tubular electrode is a cathode.
18. The electrochemical device of claim 11 further comprising an electrolytic aqueous solution having a pH of about 11 or less.
19. The electrochemical device of claim 18, wherein said electrolytic aqueous solution comprises about 7% or less of KOH.
20. The electrochemical device of claim 19, wherein said electrolytic aqueous solution further comprises ascorbic acid; phosphoric acid; citric acid; acetic acid; sorbitol; potassium carbonate; propionic acid; sodium propionate; sucrose; lithium carbonate; lithium citrate; magnesium chloride; sodium teraborate; sodium acetate; sodium sulfate, or a combination thereof.
Type: Application
Filed: Oct 24, 2013
Publication Date: Apr 30, 2015
Inventors: Gary Nicholson (Beijing), Darrel Vance Smith (Taiwai Shatin, N.T.), Domanique Nicholson Leonowicz (London)
Application Number: 14/062,064
International Classification: C25B 11/02 (20060101); C25B 9/06 (20060101);