DE102007039478A1 - Hydrogen generator and method for generating hydrogen - Google Patents

Abstract

The present invention relates to a process for the production of hydrogen and a hydrogen generator based on a hydrogen-containing compound and a solvent, wherein the hydrogen release takes place in a spatially separated from the storage / storage reactor, wherein this with a dissolved in the solvent hydrogen-containing compound continuously or is supplied discontinuously. The solvent is for the sole purpose of transporting the hydrogen-containing compound from the repository to the reactor and is not consumed during the hydrogen release. Thus, the hydrogen generator can be operated with a comparatively small amount of solvent circulating in the circulation.

Description

This The invention relates to a process for the production of hydrogen and a hydrogen generator based on a hydrogen-containing Compound and a solvent, in which the release of hydrogen in one of the storage / storage spatial Separate reactor takes place, this one with in the solvent dissolved hydrogen-containing compound continuously or discontinuously is supplied. The solvent serves exclusively for the purpose of transporting the hydrogen-containing compound from Repository to the reactor and will during the hydrogen release not consumed. Thus, the hydrogen generator with a operated comparatively small amount of solvent, which circulated in the circulation.

task The present invention is a method for the production of To provide hydrogen from hydrogen-containing compounds, the easy to carry out and low maintenance. It is also the task of the present Invention, one for carrying belonging to the method Device, namely a hydrogen generator.

These Task is relative the method with the features of claim 1, with respect to Device solved with the features of claim 18. With Claim 26 are uses of the hydrogen generator called. The dependent ones claims make advantageous developments of the method or the Device dar.

Thus, according to the invention a process for producing hydrogen from hydrogen-containing Provided compounds in which at least one hydrogen-containing Compound by means of a liquid Transport medium from a for the hydrogen-containing compound provided in reservoir one from the reservoir spatial transferred separate reactor and in the reactor, the hydrogen-containing compound to hydrogen and further reaction products is reacted, wherein the liquid transport medium is not reactively involved in the reaction in the reactor and so during the Implementation is not consumed. The advantage of this invention over the Previous systems is the use of a solvent containing the hydrogen-containing Dosed compound transported into the reactor and during the Reaction is not consumed. This allows very high storage densities can be achieved and the system can easily over the selected flow rate be managed.

Preferably, the transport medium is a solvent for the at least one hydrogen-containing compound. In particular, the transport medium is an organic solvent, a boron-containing solvent, ionic liquids and / or mixtures thereof, wherein the organic solvent is preferably an ether having at least one -CR ₂ -O-CR ₂ group with R = H, CH ₃ , C ₂ H ₅ , iso-C ₃ H ₇ , C ₄ H ₉ , tert-C ₄ H ₉ , in particular glyme, diglyme, triglyme or tetraglyme, or an alcohol having at least one OH group, in particular methanol, ethanol, n-propanol or iso-propanol. The boron-containing solvents may be z. Example, a boron-containing Lewis acid, in particular B (OCH ₃ ) ₃ , B (OC ₂ H ₅ ) ₃ or B [N (CH ₃ ) ₂ ] ₃ , and / or a boron-containing acid-base complex, in particular B ( OCH ₃ ) ₃ NH ₃ , B (OC ₂ H ₅ ) ₃ NH ₃ , BH ₃ Py or BH ₃ N (C ₂ H ₅ ) ₃ . In the ionic liquids z. As nitrogen-containing ammonium-based, imidazolium-based or pyridinium-based compounds are preferred, in particular is used as imidazolium-based compound 1-butyl-3-methylimidazolium-tetrafluoroborate use.

In an advantageous embodiment are the hydrogen-containing compounds selected from the group consisting from complex hydrides, in particular borohydrides or alanates, or adducts thereof, metal hydrides and / or boron-nitrogen compounds, in particular borazane or substituted borazane. The hydrogen-containing Compound may be in solid, liquid or paste form in the storage container are located. Preferably, the concentration of at least one hydrogen-containing compound in the liquid transport medium between 10 to 90 wt .-%, preferably between 20 to 60 wt .-%, especially before given to set between 30 and 50 wt .-%.

The Activation of the decomposition reaction takes place principally thermally, especially at temperatures between 20 and 160 ° C, preferably between 25 and 110 ° C, more preferably between 70 and 110 ° C. Is the hydrogen release an exothermic process, e.g. B. decomposition of borazane, is the supply of just heat while the starting phase required. Due to the heat of reaction keeps the process then independently the working temperature. The activation of the decomposition reaction can z. B. thermally at elevated Temperature without catalyst, or at lower temperatures with Catalyst. Naturally it is also conceivable that the catalyst only at higher temperatures allows the decomposition reaction.

In order to minimize the activation energy of the decomposition reaction, it is advantageous if the decomposition of the hydrogen-containing compounds is catalytically activated. In this case, all known from the prior art catalysts, for. B. homogeneous or heterogeneous catalysts, in particular from the group of precious metals be used.

Of the Use of heterogeneous catalysts is preferred since they are multiply are usable. Catalysts are applied to support structures to one possible size specific reaction surface to achieve at minimal amount of catalyst, for. B. on honeycomb structures (Monoliths), in the form of coatings and / or as pellets in Packings. Consequently prevents v. a. the high quality noble metal catalysts dissolved in the transport medium and be disposed of with this.

The Decomposition reaction can be accelerated by catalytic Amounts of water are added to the reaction mixture.

Farther the process is characterized by the fact that the pressure of the resulting Hydrogen preferably between 1 and 800 bar, more preferably between 1 and 30 bar can be regulated. The flow rate the solution is preferably between 0.1 to 100 ml / min, particularly preferred adjusted between 0.5 and 50 ml / min.

Of the Hydrogen generator preferably produces hydrogen in one Range from 2 Nl / h to 200 Nl / h (release rate). Based on the lower calorific value of hydrogen corresponds to a power from 6 W to 600 W. Preferably, the hydrogen generator can be 16.7 Nl / h to 84 Nl / h (50 W to 250 W) release hydrogen.

• a) mindestens einen Vorratsbehälter für mindestens eine wasserstoffhaltige Verbindung,
• b) mindestens einen Reaktor zur Umsetzung der mindestens einen wasserstoffhaltigen Verbindung zu Wasserstoff und weiteren Reaktionsprodukten sowie
• c) mindestens eine Pumpe für den Transport der wasserstoffhaltigen Verbindung in einem flüssigen Transportmedium,
• d) wobei die Komponenten a) bis c) zur Gewährleistung eines Stofftransports verbunden sind.

The invention also provides a hydrogen generator comprising

• a) at least one storage container for at least one hydrogen-containing compound,
• b) at least one reactor for reacting the at least one hydrogen-containing compound to hydrogen and further reaction products and
• c) at least one pump for transporting the hydrogen-containing compound in a liquid transport medium,
• d) wherein the components a) to c) are connected to ensure a mass transfer.

Of the Reactor is preferred as a flow reactor, tubular reactor and / or stirred tank educated.

to Separation of solid, resulting in the reaction products is advantageous if in addition one Separator for the continuous or portionwise separation of these Products is available.

In a further advantageous embodiment is provided that in addition a container for the collection of other reaction products, in particular solid Reaction products is included.

Around to ensure continuous operation, it is further advantageous if the components of the hydrogen generator in a circulatory system are arranged.

Especially efficient is an arrangement of the components of the hydrogen generator in a circulatory system. Alternatively, however, it is equally possible that the components are arranged in a one-way flow system.

use finds the hydrogen generator in the filling of hydrogen pressure accumulators and Metal hydride storage and for the direct supply of fuel cells.

The The present invention will become apparent from the following explanations as well as the figures closer described, without the invention to the said specific embodiments restrict to want.

there demonstrate

1 the principal components of a hydrogen generator, wherein the individual components are arranged in a circuit,

2 a more detailed embodiment of a circular hydrogen reactor with associated extraction device for the hydrogen,

3 an alternative embodiment of the hydrogen generator, which is designed according to the flow principle.

• – in einem Vorratsbehälter 1 die wasserstoffhaltige Verbindung in fester oder auch flüssiger Form bevorratet wird,
• – bei Bedarf diese wasserstoffhaltige Verbindung in einem Lösungsmittel zum Transport gelöst wird,
• – die Lösung zu einem räumlich getrennten Zersetzungsort (Reaktor 3) transportiert wird,
• – die Wasserstofffreisetzung in diesem Reaktor 3 katalytisch oder nicht-katalytisch, unter Umgebungsbedingungen oder thermisch aktiviert erfolgt,
• – nach Dehydrierung der Verbindung die Zersetzungsprodukte mit der Restlösung abtransportiert werden,
• – die gegebenenfalls auftretenden festen Reaktionsprodukte in einem räumlich getrennten Separator 4 abgeschieden werden
• – und das Lösungsmittel bzw. die Restlösung im Kreislauf zirkuliert oder beim Durchlaufprinzip wieder verwendet wird.

The principle of the present invention is based on that:

• - in a storage container 1 the hydrogen-containing compound is stored in solid or liquid form,
• If necessary, this hydrogen-containing compound is dissolved in a solvent for transport,
• - The solution to a spatially separated decomposition site (reactor 3 ) is transported,
• - the hydrogen release in this reactor 3 catalytically or non-catalytically, under ambient conditions or thermally activated,
• After dehydrogenation of the compound, the decomposition products are removed with the residual solution,
• - The optionally occurring solid reaction products in a spatially separated separator 4 be deposited
• - And the solvent or the residual solution circulates in the circulation or is used again in the flow principle.

• – thermische Wasserstofffreisetzung durch Zuführung von Wärme (z. B. durch elektrische Aufheizung oder Nutzung von Abwärme) und damit bei erhöhter Temperatur bis 160°C, besser zwischen Raumtemperatur und 110°C, vorzugsweise zwischen 70°C und 110°C;
• – katalytische Wasserstofffreisetzung durch Einsatz heteroger Katalysatoren, z. B. Edelmetalle der Pt-Gruppe (Pt, Pd) oder homogener Katalysatoren bei Temperaturen nahe Raumtemperatur. Die heterogenen Katalysatoren sind vorzugsweise geträgert auf – Wabenstruktur (Monolithe) – beschichtete Rohre, Reaktorwand – Pellets in Schüttungen

The reactor is a flow or tubular reactor (plug flow) or stirred tank (mixed flow). The hydrogen release takes place in the reactor according to the following principles:

• - Thermal release of hydrogen by supplying heat (eg., By electrical heating or use of waste heat) and thus at elevated temperature up to 160 ° C, better between room temperature and 110 ° C, preferably between 70 ° C and 110 ° C;
• - Catalytic hydrogen release by use of heterogeneous catalysts, eg. B. noble metals of the Pt group (Pt, Pd) or homogeneous catalysts at temperatures near room temperature. The heterogeneous catalysts are preferably supported on - honeycomb (monoliths) - coated tubes, reactor wall - pellets in beds

• – z. B. ein komplexes Metallhydrid aus der Gruppe der Borhydride [BH₄-] oder der Aluminiumhydride [AIH₄-] mit Metallkationen aus den ersten drei Hauptgruppen, wie z. B. Lit, Mg²⁺, Al³⁺,
• – oder Addukte, bestehend aus einem komplexen Metallhydrid und einer wasserstoffhaltigen Base, wie z. B. Mg(BH₄)₂·6NH₃,
• – oder chemische Hydride, vorzugsweise aus der Gruppe der Bor-Stickstoffverbindungen. Besonders geeignet sind der Borwasserstoff-Ammoniak-Komplex BH₃NH₃ oder der Borwasserstoff-Methylamin-Komplex BH₃NH₂CH₃,

The hydrogen-containing compound may be in solid, liquid or paste form in the reservoir 1 are located. As a connection z. As complex metal hydrides or chemical hydrides are used:

• - z. B. a complex metal hydride from the group of borohydrides [BH ₄ -] or the aluminum hydrides [AIH ₄ -] with metal cations from the first three main groups, such as. B. Lit, Mg ²⁺ , Al ³⁺ ,
• - or adducts consisting of a complex metal hydride and a hydrogen-containing base, such as. B. Mg (BH ₄ ) ₂ .6NH ₃ ,
• - or chemical hydrides, preferably from the group of boron-nitrogen compounds. Particularly suitable are the boron hydride-ammonia complex BH ₃ NH ₃ or the borohydride-methylamine complex BH ₃ NH ₂ CH ₃ ,

• – Lösungsmittel mit einer oder mehreren -CR₂-O-CR₂-Gruppen (u. a. mit R = H, CH₃, C₂H₅, C₃H₇, iso-C₃H₇, C₄H₉, tert-C₄H₉), insbesondere die Glyme CH₃(OCH₂CH₂)₂OCH₃ (Diglym), CH₃(OCH₂CH₂)₃OCH₃, (Triglym), CH₃(OCH₂CH₂)₄OCH₃ (Tetraglym),
• – borhaltige Lösungsmittel, insbesondere borhaltige Lewis-Säuren, z. B. B(OCH₃)₃, B(OC₂H₅)₃, B[N(CH₃)₂]₃, oder borhaltige Säure-Base-Komplexe, z. B. BH₃Py, BH₃N(C₂H₅)₃, B(OCH₃)₃·NH₃, B(OC₂H₅)₃·NH₃,
• – ionische Flüssigkeiten, vorzugsweise aus der Gruppe der stickstoffhaltigen Ammonium-basierten, Imidazolium-basierten oder Pyridinium-basierten Verbindungen, z. B. 1-Butyl-3-methylimidazolium tetrafluoroborate [BMIM][BF₄]

The solvents used are organic solvents, water or else ionic liquids. The solvent is used several times to minimize the amount used in the circuit. This is possible because the solvent is chosen such that it does not interfere with the release of hydrogen from the hydrogen-containing compound and thus is not consumed in the reactor operation. In particular, solvents are used, such as. B.

• Solvent with one or more -CR ₂ -O-CR ₂ groups (inter alia with R =H, CH ₃ , C ₂ H ₅ , C ₃ H ₇ , iso-C ₃ H ₇ , C ₄ H ₉ , tert-butyl C ₄ H ₉ ), in particular the glymes CH ₃ (OCH ₂ CH ₂ ) ₂ OCH ₃ (diglyme), CH ₃ (OCH ₂ CH ₂ ) ₃ OCH ₃ , (triglymine), CH ₃ (OCH ₂ CH ₂ ) ₄ OCH ₃ (tetraglyme),
• Boron-containing solvents, in particular boron-containing Lewis acids, eg. B (OCH ₃ ) ₃ , B (OC ₂ H ₅ ) ₃ , B [N (CH ₃ ) ₂ ] ₃ , or boron-containing acid-base complexes, e.g. BH ₃ Py, BH ₃ N (C ₂ H ₅ ) ₃ , B (OCH ₃ ) ₃ .NH ₃ , B (OC ₂ H ₅ ) ₃ .NH ₃ ,
• - ionic liquids, preferably from the group of nitrogen-containing ammonium-based, imidazolium-based or pyridinium-based compounds, eg. B. 1-Butyl-3-methylimidazolium tetrafluoroborate [BMIM] [BF ₄ ]

The reaction products are obtained in dissolved form or as an insoluble solid and are removed with the solvent from the decomposition site. If they fall in solid form, they will be in a Seperator 4 separated from the residual solution. In liquid form, they circulate with the solution in the circulation. In the latter case, the solvent can be chosen such that the dissolved reaction products catalyze the further release of hydrogen (autocatalysis).

The hydrogen generator 100 can be realized as a pump-around system or as a once-through system.

In 1 are the principal components of the hydrogen generator 100 shown. Therein is the hydrogen-containing compound from which the hydrogen release takes place in a storage container 1 , wherein in the embodiment as shown in 1 is shown, nor a separate storage tank 9 is present for the particular solvent. Through the pump 2 circulation in the system is guaranteed, so that the solvent in the container 9 stored by entry into the storage container 1 is pumped for the hydrogen-containing compound and dissolves the hydrogen-containing compound. This solution is in the reactor 3 registered in the z. B. catalytically and / or by thermal activation hydrogen generation takes place. For separation of any resulting solid reaction products is still a separator 4 for example, mechanical means such. As sieves or filters may contain to separate such solids.

In 2 is a pumped-around system. The hydrogen-containing compound is in dissolved liquid form in a reservoir 1 Alternatively, the hydrogen-containing compound is stored in pasty or solid form and, if necessary, dissolved in the solvent during operation. With the help of the pump 2 the solution is in the reactor 3 transported, in which the hydrogen is released. The solid or dissolved reaction products who removed by means of the pump from the reactor. Solid products are stored in another container 4 collected. Into the system can additionally after the reactor 3 a heat exchanger can be integrated. Thus, the waste heat of the product is used to preheat the input material. In addition, the precipitation of the solid reaction products can be facilitated.

The solvent is circulated several times in the circulation, whereby the men used ge can be minimized. This is possible because the solvent is chosen such that it does not interfere with the release of hydrogen from the hydrogen-containing compound and thus is not consumed in the reactor operation. The liquid reaction products circulate in the solution in the circulation. In this case, the solvent can be chosen such that the dissolved reaction products catalyze the further hydrogen release (autocatalysis). To purify the generated hydrogen, a filter is connected to the reactor 5 present, which separates, for example, entrained by the hydrogen flow of solid particles or droplets. For pressure regulation is following the filter 5 a valve 6 existing, for example, by feedback via a controller 7 , z. As a computer, to regulate the pressure in the line 8th can be controlled. Depending on the need of the required pressure, which may for example be between 10 and 800 bar, the valve must 6 be designed as high or low pressure valve.

In 3 the hydrogen generator is realized as a one-time system (once-through). Here, the solution is not pumped repeatedly, but from the reservoir 1 containing the hydrogen-containing compound as well as the solvent at the same time, only once through the reactor 3 in the collection container 10 transported. As in 2 Here is also a system for cleaning or pressure regulation of the resulting hydrogen present.

Claims (27)

Process for the production of hydrogen from hydrogen-containing compounds, in which at least one hydrogen-containing compound is prepared by means of a liquid transport medium from a reservoir provided for the hydrogen-containing compound (US Pat. 1 ) in one of the reservoir ( 1 ) spatially separated reactor ( 3 ) and in the reactor ( 3 ) the hydrogen-containing compound is converted into hydrogen and further reaction products, the liquid transport medium reacting in the reactor ( 3 ) is not reactively involved and is thus not consumed during the implementation. Method according to claim 1, characterized in that that the transport medium is a solvent for the at least one hydrogen-containing compound. Method according to one of the preceding claims, characterized characterized in that the transport medium is an organic solvent, a boron-containing solvent, an ionic liquid and / or Mixtures of this is. Process according to the preceding claim, characterized in that the organic solvent is an ether having at least one -CR ₂ -O-CR ₂ group with R =H, CH ₃ , C ₂ H ₅ , iso-C ₃ H ₇ , C ₄ H ₉ , tert-C ₄ H ₉ , in particular glyme, diglyme, triglyme or tetraglyme, or an alcohol having at least one OH group, in particular methanol, ethanol, n-propanol or iso-propanol. A method according to claim 3, characterized in that the boron-containing solvent is a boron-containing Lewis acid, in particular B (OCH ₃ ) ₃ , B (OC ₂ H ₅ ) ₃ or B [N (CH ₃ ) ₂ ] ₃ , and / or a boron-containing acid-base complex, in particular B (OCH ₃ ) ₃ NH ₃ , B (OC ₂ H ₅ ) ₃ NH ₃ , BH ₃ Py or BH ₃ N (C ₂ H ₅ ) ₃ . Method according to claim 3, characterized that the ionic liquid selected is from the group of nitrogen-containing ammonium-based, imidazolium-based or pyridinium-based Links. Method according to Claim 6, characterized that as imidazolium-based Compound 1-butyl-3-methylimidazolium tetrafluoroborate is used. Method according to one of the preceding claims, characterized characterized in that the at least one hydrogen-containing compound selected is from the group consisting of complex hydrides, in particular Borohydrides or alanates, or adducts thereof, metal hydrides and / or boron-nitrogen compounds, in particular borazane or substituted borazane. Method according to one of the preceding claims, characterized in that the concentration of the at least one hydrogen-containing compound is in the liquid Transport medium between 10 to 90 wt .-%, preferably between 20 to 60 wt .-%, more preferably between 30 and 50 wt .-% is. Method according to one of the preceding claims, characterized characterized in that the decomposition of the hydrogen-containing compounds is activated catalytically. Method according to one of the preceding claims, characterized characterized in that homogeneous or heterogeneous catalysts, in particular from the group of precious metals. Method according to the preceding claim, characterized characterized in that the catalysts are applied to carrier structures, z. B. on honeycomb structures (monoliths), in the form of coatings and / or as pellets in beds. Method according to one of the preceding Claims, characterized in that the decomposition of the hydrogen-containing compounds is thermally activated. Method according to the preceding claim, characterized characterized in that the thermal activation at temperatures between 20 and 160 ° C, preferably between 25 and 110 ° C, more preferably between 70 and 110 ° C takes place. Method according to one of the preceding claims, characterized characterized in that the hydrogen release by adding catalytic Amounts of water is accelerated. Method according to one of the preceding claims, characterized characterized in that the pressure of the resulting hydrogen between 1 and 800 bar, preferably between 1 and 30 bar is regulated. Method according to one of the preceding claims, characterized characterized in that the flow rate of the solution is between 0.1 to 100 ml / min, is preferably set between 0.5 and 50 ml / min. Method according to one of the preceding claims, characterized characterized in that the rate of release of hydrogen in the range of 2 to 200 Nl / h, in particular in the range of 16 to 84 Nl / h. Hydrogen generator ( 100 ) comprising a) at least one storage container ( 1 ) for at least one hydrogen-containing compound, b) at least one reactor ( 3 ) for reacting the at least one hydrogen-containing compound to hydrogen and further reaction products, and c) at least one pump ( 2 ) for the transport of the hydrogen-containing compound in a liquid transport medium, wherein the components a) to c) are connected to ensure a mass transfer. Hydrogen generator ( 100 ) according to claim 19, characterized in that the at least one reactor ( 3 ) is a flow reactor, a tubular reactor and / or a stirred tank. Hydrogen generator ( 100 ) according to claim 19 or 20, characterized in that additionally a separator ( 4 ) is contained for the separation of solid reaction products. Hydrogen generator ( 100 ) according to one of claims 19 to 21, characterized in that the reactor ( 3 ) a filter ( 5 ) is connected downstream to purify the hydrogen. Hydrogen generator ( 100 ) according to one of claims 19 to 22, characterized in that in addition a container ( 10 ) is included for the collection of further reaction products, in particular solid reaction products. Hydrogen generator ( 100 ) according to one of claims 19 to 23, characterized in that the components of the hydrogen generator are arranged in a circulatory system. Hydrogen generator ( 100 ) according to one of claims 19 to 23, characterized in that the components of the hydrogen generator are arranged in a one-way flow-through system. Hydrogen generator ( 100 ) according to one of claims 19 to 25 for carrying out the method according to one of claims 1 to 17. Use of the hydrogen generator ( 100 ) according to any one of claims 19 to 26 for filling hydrogen pressure accumulators and metal hydride storage and for the direct supply of fuel cells.