WO2000046869A2 - Method and device for quantitatively determining alcohols by means of fuel cells - Google Patents
Method and device for quantitatively determining alcohols by means of fuel cells Download PDFInfo
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- WO2000046869A2 WO2000046869A2 PCT/DE2000/000341 DE0000341W WO0046869A2 WO 2000046869 A2 WO2000046869 A2 WO 2000046869A2 DE 0000341 W DE0000341 W DE 0000341W WO 0046869 A2 WO0046869 A2 WO 0046869A2
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
- G01N27/403—Cells and electrode assemblies
- G01N27/404—Cells with anode, cathode and cell electrolyte on the same side of a permeable membrane which separates them from the sample fluid, e.g. Clark-type oxygen sensors
- G01N27/4045—Cells with anode, cathode and cell electrolyte on the same side of a permeable membrane which separates them from the sample fluid, e.g. Clark-type oxygen sensors for gases other than oxygen
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/02—Food
- G01N33/14—Beverages
- G01N33/146—Beverages containing alcohol
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/08—Fuel cells with aqueous electrolytes
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/10—Fuel cells with solid electrolytes
- H01M8/1009—Fuel cells with solid electrolytes with one of the reactants being liquid, solid or liquid-charged
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/30—Hydrogen technology
- Y02E60/50—Fuel cells
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- the invention relates to a method and a device for the quantitative determination of alcohols.
- an osmotic measuring device with a flow cell with which, for example, the alcohol content in beer is continuously determined.
- the pressure in the measuring cell is measured in a measuring cell separated from the flow cell by a membrane with the aid of a pressure sensor. This drops due to the osmotic pressure with increasing concentration of alcohol in the
- Flow cell and can thus be used as a measure for determining the alcohol content in beer.
- the object of the invention is to provide a further method and a further device with which alcohols can be determined quantitatively.
- the method and the device result from the related claims.
- the sophisticated method uses a fuel cell for the quantitative determination of alcohols.
- a fuel cell has a cathode, an anode and one located between the anode and cathode
- Electrolytes An anode space borders on the anode.
- a cathode space borders on the cathode.
- methanol and water are fed to the anode compartment as working gas.
- oxygen or air is considered
- Hydrogen ions are formed from the methanol and water at the anode using a catalyst.
- the hydrogen ions pass through the electrolyte, which typically consists of a membrane, eg Nafion ® 117 or National ®
- the medium to be measured is liquid and / or gaseous and contains the alcohol to be determined.
- the measuring medium can be, for example, a water-methanol mixture or a water-methanol-C0 2 mixture.
- the measuring medium with the alcohol flows through an electrode space of the fuel cell. A fluid is fed to the other electrode space.
- the alcohol reaches after indirect or direct supply to the anode. Immediate supply means that the alcohol is passed directly to the anode together with the measuring medium, while with the indirect supply the alcohol must first pass the electrolyte in order to reach the anode.
- the alcohol is oxidized at the anode. This releases electrons.
- the resulting hydrogen ions (protons) pass through the electrolyte and are reduced at the cathode by taking up the electrons.
- the voltage and / or the current in the fuel cell are measured and used as a measure of the concentration of alcohol in the measuring medium.
- reference data and the comparison of this reference data with measured data represent the correct use of the current / voltage as a measure of the concentration.
- the measuring medium with the alcohol flows through the anode compartment as an electrode compartment of the fuel cell.
- An oxidizing agent is supplied as fluid to the cathode compartment as another electrode compartment.
- Suitable oxidizing agents are, for example, air, oxygen or hydrogen peroxide.
- the alcohol is oxidized at the anode. This releases electrons.
- the resulting hydrogen ions (protons) pass through the electrolyte and react with the oxygen from the oxidizing agent to form water at the cathode, taking up the electrons.
- a current flows that is generated by the fuel cell.
- a resistor is connected between the anode and the cathode. The voltage and / or the current are measured in the fuel cell and used as a measure of the concentration of alcohol in the measuring medium.
- a voltage is applied to a fuel cell from the outside in order to force oxidation of the alcohol at the anode.
- the voltage is applied so that the electrode space through which the measuring medium flows is the anode space and that an inert gas is the
- Cathode space is fed as another electrode space.
- An inert gas is a gas that does not react chemically in the fuel cell. Inert gases are e.g. Nitrogen or noble gases, such as argon or helium. The alcohol to be determined quantitatively is at the
- a voltage is likewise applied to a fuel cell from the outside in order to achieve the aforementioned effect.
- the voltage is applied such that the electrode space through which the measuring medium flows is the cathode space and an inert gas as fluid is fed to the anode space as another electrode space.
- the electrolyte is permeable to alcohols and can in particular be a membrane. Examples of such membranes are the cation exchange membranes National ® 117 or National ® 105.
- the alcohol first passes through the electrolyte, before it is oxidized at the anode.
- the resulting hydrogen ions diffuse through the electrolyte back to the cathode, where they react to form hydrogen.
- the resulting current is measured and used as a measure of the concentration of alcohol in the measuring medium.
- the device for determining alcohols according to claim 5 contains a fuel cell, the electrolyte of which is permeable to alcohols. Means are also available for measuring the voltage or the current generated in the fuel cell. Means for measuring the voltage generated in the fuel cell are e.g. a voltmeter that drops across a resistor between the anode and cathode
- Tension measures A means of measuring the current generated is e.g. an ammeter connected between the anode and cathode.
- Determination of alcohols also contains means to apply external voltage to the fuel cell.
- a means is e.g. a battery.
- the voltage to be applied should be so high that the potential difference necessary for the oxidation of the alcohol is given.
- the voltage should e.g. be at least 250 mV.
- an evaluation means is available. With the aid of the evaluation means, an alcohol concentration is determined from the measured voltage or the measured current.
- the Evaluation means can in particular contain a memory in which reference data are stored and a comparison means with which the measured data are compared with the reference data. Reference data are current or voltage data from measurements with a known alcohol content in the measuring medium.
- the evaluation means can also have a calibration curve. The alcohol content of this mixture can be determined by comparing the reference data with the measured current or voltage values of a mixture with an unknown alcohol content.
- Fig. 1 shows the schematic structure of a methanol fuel cell
- Fig. 2 shows the voltage concentration curve of a methanol fuel cell in the 0 2 -bet ⁇ eb
- the method according to the invention uses a fuel cell, here a methanol fuel cell, as shown in FIG. 1, for detecting alcohol, here methanol.
- the fuel cell consists of an anode compartment 1, which adjoins the anode 2 and a cathode compartment 5, which adjoins the cathode 4.
- the electrolyte 3 is located between the anode and the cathode, in this case a membrane permeable to alcohol.
- Anode and cathode are connected to one another via a conductor 6.
- a conductor In the conductor is a resistor R and an ammeter A switched. The voltage drop across the resistor is measured with a voltmeter V.
- a water-methanol mixture with an unknown methanol content is supplied to the anode compartment as the measuring medium, while air is supplied to the cathode compartment as a fluid.
- the methanol oxidizes at the anode according to the equation:
- the necessary electrons are released from the cathode.
- the voltage resulting from these processes can be read on the voltmeter (V). Due to the diffusion of the methanol through the electrolyte to the cathode, a mixed potential is formed at the cathode and the cathode process is inhibited, and the greater the higher the methanol concentration in the measuring medium. Together with reference data from measurements with a known methanol content and subsequent comparison, the voltage read can be used as a measure of the concentration of methanol in the measuring medium.
- Figure 2 shows the graph of the dependence of the measured voltage on the
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Abstract
Description
B e s c h r e i b u n g Description
Verfahren und Vorrichtung zur quantitativen Bestimmung von AlkoholenMethod and device for the quantitative determination of alcohols
Die Erfindung betrifft ein Verfahren und eine Vorrichtung zur quantitativen Bestimmung von Alkoholen.The invention relates to a method and a device for the quantitative determination of alcohols.
Aus DE 196 40 063 Cl ist eine osmotische Meßeinrichtung mit einer Durchflußzelle bekannt, mit der beispielsweise der Alkoholgehalt in Bier kontinuierlich bestimmt wird. Dabei wird in einer durch eine Membran von der Durchflußzelle getrennten Meßzelle mit Hilfe eines Druckaufnehmers der Druck in der Meßzelle gemessen. Dieser fällt auf Grund des osmotischen Drucks mit steigender Konzentration an Alkohol in derFrom DE 196 40 063 Cl an osmotic measuring device with a flow cell is known with which, for example, the alcohol content in beer is continuously determined. The pressure in the measuring cell is measured in a measuring cell separated from the flow cell by a membrane with the aid of a pressure sensor. This drops due to the osmotic pressure with increasing concentration of alcohol in the
Durchflußzelle und kann so als Maß zur Bestimmung des Alkoholgehalts in Bier eingesetzt werden.Flow cell and can thus be used as a measure for determining the alcohol content in beer.
Aufgabe der Erfindung ist es, ein weiteres Verfahren sowie eine weitere Vorrichtung zu schaffen, mit dem/der Alkohole quantitativ bestimmt werden können.The object of the invention is to provide a further method and a further device with which alcohols can be determined quantitatively.
Die Aufgabe wird erfindungsgemäß gelöst durch ein Verfahren nach dem Anspruch 1 und einer Vorrichtung nach Anspruch 5. Vorteilhafte Ausführungen desThe object is achieved according to the invention by a method according to claim 1 and a device according to claim 5. Advantageous embodiments of the
Verfahrens bzw. der Vorrichtung ergeben sich aus den rückbezogenen Ansprüchen. Das anspruchsgemaße Verfahren setzt eine Brennstoffzelle zur quantitativen Bestimmung von Alkoholen ein.The method and the device result from the related claims. The sophisticated method uses a fuel cell for the quantitative determination of alcohols.
Eine Brennstoffzelle weist eine Kathode, eine Anode sowie einen zwischen Anode und Kathode befindlichenA fuel cell has a cathode, an anode and one located between the anode and cathode
Elektrolyten auf. An die Anode grenzt ein Anodenraum. An die Kathode grenzt ein Kathodenraum.Electrolytes. An anode space borders on the anode. A cathode space borders on the cathode.
Bei einer Methanol-Brennstoffzelle wird Methanol und Wasser als Arbeitsgas dem Anodenraum zugeleitet. Auf der Kathodenseite wird Sauerstoff oder Luft alsIn a methanol fuel cell, methanol and water are fed to the anode compartment as working gas. On the cathode side, oxygen or air is considered
Oxidationsmittel zugeführt. Aus dem Methanol und dem Wasser bilden sich an der Anode mittels eines Katalysators Wasserstofflonen. Die WasserstoffIonen passieren den Elektrolyten, der typischerweise aus einer Membran besteht, z.B. Nafion® 117 oder Nation® Oxidizing agent supplied. Hydrogen ions are formed from the methanol and water at the anode using a catalyst. The hydrogen ions pass through the electrolyte, which typically consists of a membrane, eg Nafion ® 117 or Nation ®
105, und verbinden sich auf der Kathodenseite mit dem vom Oxidationsmittel stammenden Sauerstofflonen zu Wasser. Elektronen werden dabei freigesetzt und elektrische Energie erzeugt. Aus DE 196 46 487 C2 geht hervor, daß die Elektrolyte bekannter Brennstoffzellen nicht nur die Wasserstofflonen passieren lassen, sondern auch teilweise die Hydrathullen der Wasserstofflonen oder ein Teil des Meßmediums. Dies fuhrt zur Mischpotentialbildung an der Kathode und damit zu einer geringeren Zellspannung.105, and combine on the cathode side with the oxygen ion originating from the oxidizing agent to form water. Electrons are released and electrical energy is generated. DE 196 46 487 C2 shows that the electrolytes of known fuel cells not only let the hydrogen ions pass, but also partially the hydrathulles of the hydrogen ions or part of the measuring medium. This leads to the formation of mixed potential at the cathode and thus to a lower cell voltage.
Das anspruchsgemaße Meßmedium ist flussig und/oder gasformig und enthalt den zu bestimmenden Alkohol. Das Meßmedium kann z.B. eine Wasser-Methanol-Mischung oder eine Wasser-Methanol-C02-Mιschung sein. Das Meßmedium mit dem Alkohol durchströmt einen Elektrodenraum der Brennstoffzelle. Dem anderen Elektrodenraum wird ein Fluid zugeleitet. Der Alkohol gelangt nach mittelbarer oder unmittelbarer Zuleitung zur Anode. Unmittelbare Zuleitung bedeutet, daß der Alkohol zusammen mit dem Meßmedium direkt an die Anode geleitet wird, wahrend bei der mittelbaren Zuleitung der Alkohol zunächst den Elektrolyten passieren muß, um zur Anode zu gelangen. An der Anode wird der Alkohol oxidiert. Dabei werden Elektronen freigesetzt. Die entstehenden Wasserstoffionen (Protonen) passieren den Elektrolyten und werden an der Kathode unter Aufnahme der Elektronen reduziert. Bei leitender Verbindung von Anode undThe medium to be measured is liquid and / or gaseous and contains the alcohol to be determined. The measuring medium can be, for example, a water-methanol mixture or a water-methanol-C0 2 mixture. The measuring medium with the alcohol flows through an electrode space of the fuel cell. A fluid is fed to the other electrode space. The alcohol reaches after indirect or direct supply to the anode. Immediate supply means that the alcohol is passed directly to the anode together with the measuring medium, while with the indirect supply the alcohol must first pass the electrolyte in order to reach the anode. The alcohol is oxidized at the anode. This releases electrons. The resulting hydrogen ions (protons) pass through the electrolyte and are reduced at the cathode by taking up the electrons. When the anode and
Kathode fließt ein Strom. Die Spannung und/oder der Strom in der Brennstoffzelle werden gemessen und als Maß für die Konzentration an Alkohol in dem Meßmedium verwendet. Insbesondere Referenzdaten und der Vergleich dieser Referenzdaten mit gemessenen Daten stellen die anspruchsgemäße Verwendung des Stroms/des Spannung als Maß für die Konzentration dar.A current flows through the cathode. The voltage and / or the current in the fuel cell are measured and used as a measure of the concentration of alcohol in the measuring medium. In particular, reference data and the comparison of this reference data with measured data represent the correct use of the current / voltage as a measure of the concentration.
In einer vorteilhaften Ausgestaltung des Verfahrens durchströmt das Meßmedium mit dem Alkohol den Anodenraum als einen Elektrodenraum der Brennstoffzelle. Dem Kathodenraum als anderem Elektrodenraum wird ein Oxidationsmittel als Fluid zugeleitet. Geeignete Oxidationsmittel sind z.B. Luft, Sauerstoff oder Wasserstoffperoxid. Der Alkohol wird an der Anode oxidiert. Dabei werden Elektronen freigesetzt. Die entstehenden Wasserstoffionen (Protonen) passieren den Elektrolyten und reagieren an der Kathode unter Aufnahme der Elektronen zusammen mit dem Sauerstoff aus dem Oxidationsmittel zu Wasser. Bei leitender Verbindung von Anode und Kathode fließt ein Strom, der durch die Brennstoffzelle erzeugt wird. Zwischen Anode und Kathode ist insbesondere ein Widerstand geschaltet. Die Spannung und/oder der Strom in der Brennstoffzelle werden gemessen und als Maß für die Konzentration an Alkohol in dem Meßmedium verwende .In an advantageous embodiment of the method, the measuring medium with the alcohol flows through the anode compartment as an electrode compartment of the fuel cell. An oxidizing agent is supplied as fluid to the cathode compartment as another electrode compartment. Suitable oxidizing agents are, for example, air, oxygen or hydrogen peroxide. The alcohol is oxidized at the anode. This releases electrons. The resulting hydrogen ions (protons) pass through the electrolyte and react with the oxygen from the oxidizing agent to form water at the cathode, taking up the electrons. When the anode and cathode are connected, a current flows that is generated by the fuel cell. In particular, a resistor is connected between the anode and the cathode. The voltage and / or the current are measured in the fuel cell and used as a measure of the concentration of alcohol in the measuring medium.
In einer weiteren vorteilhaften Ausgestaltung desIn a further advantageous embodiment of the
Verfahrens wird an eine Brennstoffzelle von außen eine Spannung angelegt, um so eine Oxidation des Alkohols an der Anode zu erzwingen. Die Spannung wird so angelegt, daß der Elektrodenraum, den das Meßmedium durchströmt, der Anodenraum ist und daß ein Inertgas demIn the process, a voltage is applied to a fuel cell from the outside in order to force oxidation of the alcohol at the anode. The voltage is applied so that the electrode space through which the measuring medium flows is the anode space and that an inert gas is the
Kathodenraum als anderem Elektrodenraum zugeleitet wird. Ein Inertgas ist ein Gas, welches in der Brennstoffzelle nicht chemisch reagiert. Inertgase sind z.B. Stickstoff oder Edelgase, wie Argon oder Helium. Der quantitativ zu bestimmende Alkohol wird an derCathode space is fed as another electrode space. An inert gas is a gas that does not react chemically in the fuel cell. Inert gases are e.g. Nitrogen or noble gases, such as argon or helium. The alcohol to be determined quantitatively is at the
Anode oxidiert. Die dabei entstehenden Wasserstoffionen (Protonen) passieren den Elektrolyten und reagieren an der Kathode zu Wasserstoff. Der erzeugte Strom wird gemessen und als Maß für die Konzentration an Alkohol in dem Meßmedium verwendetAnode oxidized. The resulting hydrogen ions (protons) pass through the electrolyte and react to hydrogen at the cathode. The current generated is measured and used as a measure of the concentration of alcohol in the measuring medium
In einer weiteren vorteilhaften Ausgestaltung des Verfahrens wird an eine Brennstoffzelle ebenfalls von außen eine Spannung angelegt, um die vorhergehend genannte Wirkung zu erzielen. Die Spannung wird so angelegt, daß der Elektrodenraum, den das Meßmedium durchströmt, der Kathodenraum ist und ein Inertgas als Fluid dem Anodenraum als anderem Elektrodenraum zugeleitet wird. Der Elektrolyt ist für Alkohole durchlässig und kann insbesondere eine Membran sein. Beispiele für solche Membranen sind z.B. die Kationenaustauschermembranen Nation® 117 oder Nation® 105. Der Alkohol passiert zunächst den Elektrolyten, bevor er an der Anode oxidiert wird. Die hierbei entstehenden Wasserstoffionen diffundieren durch den Elektrolyten zurück zur Kathode, wo sie zu Wasserstoff reagieren. Der sich hierbei einstellende Strom wird gemessen und als Maß für die Konzentration an Alkohol in dem Meßmedium verwendet.In a further advantageous embodiment of the method, a voltage is likewise applied to a fuel cell from the outside in order to achieve the aforementioned effect. The voltage is applied such that the electrode space through which the measuring medium flows is the cathode space and an inert gas as fluid is fed to the anode space as another electrode space. The electrolyte is permeable to alcohols and can in particular be a membrane. Examples of such membranes are the cation exchange membranes Nation ® 117 or Nation ® 105. The alcohol first passes through the electrolyte, before it is oxidized at the anode. The resulting hydrogen ions diffuse through the electrolyte back to the cathode, where they react to form hydrogen. The resulting current is measured and used as a measure of the concentration of alcohol in the measuring medium.
Die Vorrichtung zur Bestimmung von Alkoholen nach Anspruch 5 enthält eine Brennstoffzelle, dessen Elektrolyt für Alkohole durchlässig ist. Zudem sind Mittel vorhanden, um die in der Brennstoffzelle erzeugte Spannung oder den erzeugten Strom zu messen. Mittel zur Messung der in der Brennstoffzelle erzeugten Spannung sind z.B. ein Voltmeter, welches die an einem Widerstand zwischen Anode und Kathode abfallendeThe device for determining alcohols according to claim 5 contains a fuel cell, the electrolyte of which is permeable to alcohols. Means are also available for measuring the voltage or the current generated in the fuel cell. Means for measuring the voltage generated in the fuel cell are e.g. a voltmeter that drops across a resistor between the anode and cathode
Spannung mißt. Ein Mittel zur Messung des erzeugten Stroms ist z.B. ein zwischen Anode und Kathode geschaltetes Amperemeter.Tension measures. A means of measuring the current generated is e.g. an ammeter connected between the anode and cathode.
Eine vorteilhafte Ausgestaltung der Vorrichtung zurAn advantageous embodiment of the device for
Bestimmung von Alkoholen enthält zudem Mittel, um eine Spannung von außen an die Brennstoffzelle anzulegen. Ein solches Mittel ist z.B. eine Batterie. Die anzulegende Spannung sollte so hoch sein, daß die zur Oxidation des Alkohols notwendige Potentialdifferenz gegeben ist. Für den Fall, daß Methanol oxidiert werden soll, sollte die Spannung z.B. mindestens 250 mV betragen.Determination of alcohols also contains means to apply external voltage to the fuel cell. Such a means is e.g. a battery. The voltage to be applied should be so high that the potential difference necessary for the oxidation of the alcohol is given. In the event that methanol is to be oxidized, the voltage should e.g. be at least 250 mV.
In einer weiteren vorteilhaften Ausführungsform ist ein Auswertemittel vorhanden. Mit Hilfe des Auswertemittels wird aus der gemessenen Spannung oder dem gemessenen Strom eine Alkoholkonzentration ermittelt. Das Auswertemittel kann insbesondere einen Speicher enthalten, in dem Referenzdaten gespeichert sind, und ein Vergleichsmittel, mit dem die gemessenen Daten mit den Referenzdaten verglichen werden. Referenzdaten sind Strom- oder Spannungsdaten von Messungen mit bekanntem Alkoholgehalt im Meßmedium. Das Auswertemittel kann auch eine Kalibrationskurve aufweisen. Durch Vergleich der Referenzdaten mit den gemessenen Strom- oder Spannungswerten einer Mischung mit unbekanntem Alkoholgehalt kann der Alkoholgehalt dieser Mischung bestimmt werden.In a further advantageous embodiment, an evaluation means is available. With the aid of the evaluation means, an alcohol concentration is determined from the measured voltage or the measured current. The Evaluation means can in particular contain a memory in which reference data are stored and a comparison means with which the measured data are compared with the reference data. Reference data are current or voltage data from measurements with a known alcohol content in the measuring medium. The evaluation means can also have a calibration curve. The alcohol content of this mixture can be determined by comparing the reference data with the measured current or voltage values of a mixture with an unknown alcohol content.
Die Erfindung wird nachstehend anhand eines Ausfuhrungsbeispiels zur Bestimmung von Methanol in einer Methanol-Wasser Mischung erläutert. In den dazugehörigen Zeichnungen zeigen:The invention is explained below using an exemplary embodiment for the determination of methanol in a methanol-water mixture. In the accompanying drawings:
Fig. 1 den schematischen Aufbau einer Methanol- Brennstoffzelle undFig. 1 shows the schematic structure of a methanol fuel cell and
Fig. 2 die Spannungs-Konzentrationskurve einer Methanol-Brennstoffzelle im 02-Betπeb undFig. 2 shows the voltage concentration curve of a methanol fuel cell in the 0 2 -betπeb and
Stromfluß über einen WiderstandCurrent flow through a resistor
Das erfmdungsgemaße Verfahren setzt eine Brennstoffzelle, hier eine Methanol-Brennstoffzelle, wie sie m Fig. 1 gezeigt wird, zur Erfassung von Alkohol, hier Methanol, ein.The method according to the invention uses a fuel cell, here a methanol fuel cell, as shown in FIG. 1, for detecting alcohol, here methanol.
Die Brennstoffzelle besteht aus einem Anodenraum 1, der an die Anode 2 grenzt und einem Kathodenraum 5, welcher an die Kathode 4 grenzt. Zwischen Anode und Kathode befindet sich der Elektrolyt 3, m diesem Fall eine für Alkohol durchlassige Membran. Anode und Kathode sind über einen Leiter 6 miteinander verbunden. In den Leiter ist ein Widerstand R und ein Amperemeter A geschaltet. Die über den Widerstand abfallende Spannung wird mit einem Voltmeter V gemessen.The fuel cell consists of an anode compartment 1, which adjoins the anode 2 and a cathode compartment 5, which adjoins the cathode 4. The electrolyte 3 is located between the anode and the cathode, in this case a membrane permeable to alcohol. Anode and cathode are connected to one another via a conductor 6. In the conductor is a resistor R and an ammeter A switched. The voltage drop across the resistor is measured with a voltmeter V.
Dem Anodenraum wird als Meßmedium eine Wasser-Methanol Mischung mit unbekanntem Methanolgehalt zugeführt während dem Kathodenraum als Fluid Luft zugeführt wird. Das Methanol oxidiert an der Anode nach der Gleichung:A water-methanol mixture with an unknown methanol content is supplied to the anode compartment as the measuring medium, while air is supplied to the cathode compartment as a fluid. The methanol oxidizes at the anode according to the equation:
CH3OH + H20 -> 6 H+ + C02 + 6 e" (0,04 V)CH 3 OH + H 2 0 -> 6 H + + C0 2 + 6 e " (0.04 V)
Hierbei werden Elektronen an die Anode abgegeben. An der Kathode reagieren die Protonen, die durch die zusammen mit dem Luftsauerstoff gemäß:Here, electrons are released to the anode. At the cathode, the protons, which together with the atmospheric oxygen, react according to:
6 H+ + 3/2 02 + 6 e" -> 3 H20 (1,21 V)6 H + + 3/2 0 2 + 6 e " -> 3 H 2 0 (1.21 V)
Die dazu notwendigen Elektronen werden von der Kathode abgegeben. Die sich aus diesen Prozessen ergebene Spannung kann an dem Voltmeter (V) abgelesen werden. Durch Diffusion des Methanols durch den Elektrolyten an die Kathode bildet sich ein Mischpotential an der Kathode aus und der Kathodenprozeß wird gehemmt, und zwar um so stärker, je höher die Methanolkonzentration im Meßmedium ist. Zusammen mit Referenzdaten aus Messungen mit bekanntem Methanolgehalt und anschließendem Vergleich, kann die abgelesenen Spannung als Maß für die Konzentration an Methanol im Meßmedium herangezogen werden.The necessary electrons are released from the cathode. The voltage resulting from these processes can be read on the voltmeter (V). Due to the diffusion of the methanol through the electrolyte to the cathode, a mixed potential is formed at the cathode and the cathode process is inhibited, and the greater the higher the methanol concentration in the measuring medium. Together with reference data from measurements with a known methanol content and subsequent comparison, the voltage read can be used as a measure of the concentration of methanol in the measuring medium.
Figur 2 zeigt die graphische Auftragung der Abhängigkeit der gemessenen Spannung von derFigure 2 shows the graph of the dependence of the measured voltage on the
Ausgangskonzentration an Methanol im Meßmedium. Mit zunehmender Konzentration an Methanol sinkt die erzeugte und gemessene Spannung. Initial concentration of methanol in the measuring medium. The voltage generated and measured decreases with increasing concentration of methanol.
Claims
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19904506.2 | 1999-02-04 | ||
| DE19904506A DE19904506C2 (en) | 1999-02-04 | 1999-02-04 | Method and device for the quantitative determination of alcohols |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| WO2000046869A2 true WO2000046869A2 (en) | 2000-08-10 |
| WO2000046869A3 WO2000046869A3 (en) | 2000-11-16 |
Family
ID=7896415
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/DE2000/000341 Ceased WO2000046869A2 (en) | 1999-02-04 | 2000-02-02 | Method and device for quantitatively determining alcohols by means of fuel cells |
Country Status (2)
| Country | Link |
|---|---|
| DE (1) | DE19904506C2 (en) |
| WO (1) | WO2000046869A2 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2001035478A1 (en) * | 1999-11-08 | 2001-05-17 | Ballard Power Systems Inc. | Fuel cell (methanol) sensor with small load resistance and high oxidant supply |
| US6536262B2 (en) * | 1999-09-24 | 2003-03-25 | Siemens Aktiengesellschaft | Determination of the alcohol concentration in the electrolyte of fuel cells |
| DE102011007612A1 (en) | 2011-04-18 | 2012-10-18 | Robert Bosch Gmbh | Method for operating fuel cell of fuel cell system used in motor vehicle, involves determining fuel concentration of anode gas on basis of determined power or size of fuel cell |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3966579A (en) * | 1974-03-20 | 1976-06-29 | Kuo Wei Chang | Apparatus for measuring alcohol concentrations |
| JPS60189174A (en) * | 1984-03-07 | 1985-09-26 | Hitachi Ltd | Fuel cell |
| DE3582716D1 (en) * | 1984-10-31 | 1991-06-06 | Hitachi Ltd | LIQUID FUEL CELL. |
| EP0684469A3 (en) * | 1994-05-24 | 1996-11-20 | Siemens Ag | Apparatus for determining the concentration of alcohols. |
| DE19640063C1 (en) * | 1996-09-28 | 1998-01-08 | Forschungszentrum Juelich Gmbh | Osmotic pressure measurement arrangement |
| DE19646487C2 (en) * | 1996-11-11 | 1998-10-08 | Forschungszentrum Juelich Gmbh | Electrode-electrolyte unit for a fuel cell |
| US6306285B1 (en) * | 1997-04-08 | 2001-10-23 | California Institute Of Technology | Techniques for sensing methanol concentration in aqueous environments |
-
1999
- 1999-02-04 DE DE19904506A patent/DE19904506C2/en not_active Expired - Fee Related
-
2000
- 2000-02-02 WO PCT/DE2000/000341 patent/WO2000046869A2/en not_active Ceased
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6536262B2 (en) * | 1999-09-24 | 2003-03-25 | Siemens Aktiengesellschaft | Determination of the alcohol concentration in the electrolyte of fuel cells |
| WO2001035478A1 (en) * | 1999-11-08 | 2001-05-17 | Ballard Power Systems Inc. | Fuel cell (methanol) sensor with small load resistance and high oxidant supply |
| US6527943B1 (en) | 1999-11-08 | 2003-03-04 | Ballard Power Systems, Inc. | Fuel cell concentration sensor |
| DE102011007612A1 (en) | 2011-04-18 | 2012-10-18 | Robert Bosch Gmbh | Method for operating fuel cell of fuel cell system used in motor vehicle, involves determining fuel concentration of anode gas on basis of determined power or size of fuel cell |
Also Published As
| Publication number | Publication date |
|---|---|
| WO2000046869A3 (en) | 2000-11-16 |
| DE19904506A1 (en) | 2000-08-31 |
| DE19904506C2 (en) | 2002-10-24 |
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