WO2007128655A1

WO2007128655A1 - Method and device for purifying a gas reservoir

Info

Publication number: WO2007128655A1
Application number: PCT/EP2007/053725
Authority: WO
Inventors: Werner Gruenwald; Thorsten Allgeier; Kai Oertel; Ian Faye; Stephan Leuthner; Jan-Michael Graehn; Ulrich Mueller; Michael Hesse
Original assignee: Robert Bosch Gmbh; Basf Aktiengesellschaft
Priority date: 2006-05-04
Filing date: 2007-04-17
Publication date: 2007-11-15
Also published as: DE102006020847A1

Abstract

The invention relates to a device and a method for purifying a gas reservoir (10), in particular a sorption reservoir containing a sorption material (18). The gas reservoir is emptied into an exhaust line (58) via a tank inlet valve (26) or into an intermediate gas reservoir (20) via a purge valve (38). The sorption material (8) is heated by means of a heating unit (20). A negative pressure is generated in the gas reservoir (10) for the desorption of impurities in the sorption material (18) using a delivery unit (54).

Description

description

title

Method and apparatus for cleaning a gas storage

State of the art

Known from the prior art, powered with gaseous fuel vehicles have a compressed gas storage, which is acted upon in operation with a system pressure of about 200 bar. Such an accumulator may be filled with compressed gas only up to 80% of its volume content, the remaining 20% of the volume content is required as expansion volume for the gaseous fuel. Compressed-gas-powered motor vehicles require special petrol pumps at petrol stations, and the filling of the compressed gas container of such motor vehicles is associated with a high risk potential. On the other hand, gaseous fuel is characterized by a low lead and sulfur content, and also by an optimal combustion, especially at lower outside temperatures, which makes this fuel interesting.

The development of alternative storage devices for storage of gaseous fuel, such as CH ₄ , is currently being vigorously advanced. An alternative to the pressure accumulators mentioned above, which are designed for a pressure level of more than 200 bar operating pressure, are sorption reservoirs. Sorption reservoirs differ from the previously used conventional compressed gas reservoirs in that they contain a sorption material. By means of the sorption material, the storage density of the gaseous fuel in such a gas storage is improved, which can be achieved in particular at relatively low pressures. As sorption materials are used in the context of physisorption, for example zeolites and pure activated carbon; in the context of chemisorption metal hydrides are used. The sorption materials used can, in addition to the gas to be stored, such as CH ₄ , also impurities, such as H ₂ O and higher molecular weight hydrocarbons (C _x H ₅ , <1%), C ₂₊ and oils bind, but this too a reduction in the storage capacity for the actual gaseous fuel, such as CH ₄ , leads. This effect is exacerbated by accumulating impurities in the gas storage after repeated refueling operations. Contaminants also include moisture (100 ppm or less).

With respect to sorption storage, WO97 / 36819 discloses an apparatus and a method for storing hydrogen. Hydrogen is stored in a rechargeable device and released by it. The device delivers hydrogen in gaseous form as needed. A storage material in the form of a metal hydride is incorporated within the hydrogen storage in particle form, which requires no compaction or other treatment. Via partition walls, the interior of the hydrogen storage is subdivided into individual separate chambers, in each of which a matrix is formed, which is formed by a suitable material, for example thermally conductive aluminum foam, which forms a number of cells. The ratio of the length of these cells to the diameter of the hydrogen storage is between 0.5 and 2. Within the cells are placed the metal hydride particles or another suitable hydrogen storage medium. The hydrogen storage includes a hydrogen conduit port through which the hydrogen flows upon delivery through the metal hydride particles or upon loading of the metal hydride particles. Inside the port, filters are provided which allow hydrogen to pass but prevent the hydrogen storage medium particles from leaking out of the cells. Through a channel, which is thermally connected to the aluminum foam, a heat transfer device is shown. By means of a channel, which is flowed through by a medium, the heat released during the hydrogen extraction or hydrogen addition heat is transported from the hydrogen storage.

DE 101 10 169 A1 relates to a hydrogen storage unit. A hydrogen storage unit is proposed that includes a hydrogen storage tank that includes a hydrogen absorbing material and a filter section for removing contaminants that may be contained in the stored hydrogen gas. The impurities are removed from the hydrogen gas stored in the hydrogen storage tank, and in particular, the hydrogen absorption material is prevented from being loaded by the impurities. The filter section may be provided either inside or outside the hydrogen storage tank. In the filter section, an adsorbent material may be used to absorb the contaminants, and the filter section is provided with a heater to increase the elimination of the contaminants adsorbed in the filter section. The filter section can be regenerated during operation. Disclosure of the invention

The invention has for its object to keep mobile and stationary gas storage, in particular Sorptionsspeicher operable by removal of impurities and to keep the gas storage capacity of Sorptionsspeicher at an optimal value.

According to the invention, this object is achieved in that mobile or stationary sorption used for storing gaseous fuel to a temperature of about 350 ⁰ C, but preferably 200 ⁰ C, are heated or evacuated by means of a vacuum pump.

With the inventively proposed method for the removal of tank contaminants, the sorption storage can be cleaned regularly in order to increase its storage capacity for receiving gaseous fuel. The proposed methods can also be carried out at regular service intervals for the maintenance of the motor vehicle and are suitable both for mobile applications, in particular for installation of sorption storage in motor vehicles and for stationary gas storage, in particular sorption storage. To carry out the method proposed according to the invention, first of all the discharge valve to the consumer, in applications in vehicles operated with gaseous fuel, a valve to the internal combustion engine is closed and a service valve is opened. The tank contents still contained in the sorption can either be stored temporarily, which can be done for example in a cache, as disposed of from the sorption or used for example thermally. Thereafter, the service valve is closed and the tank can be emptied by opening the tank inlet valve to the outside in the direction of a trigger and the opening of a trigger valve in this way.

Depending on the degree of contamination of the sorbent material in the sorption storage, the purification steps listed below can be carried out in repeated cycles and in combination with each other.

By means of a heating device associated with the sorption storage or a heating device arranged outside the sorption storage, the gas storage can be heated up to a maximum temperature T _max of 350 ^° C. Will a sorption material, such as Example metal-organic frameworks (MOF) used, the heating temperature is preferably of the order of 200 ⁰ C. If the gas storage is a low pressure, the heating of the tank up to the temperature T _{max leads} to the desorption of impurities whose desorption below T _max is. The lower the pressure prevailing in the interior of the gas storage, the better the sorption yield can be achieved with regard to the discharged impurities. Ideally, an evacuation of the gas storage should be achieved. The storage temperature of the sorbent material of the gas storage can be restored via the heating temperature up to which the sorption material of the gas storage is heated, and the number of heating processes.

The sorption of the gas storage can also be done by evacuating the gas storage to a pressure drop to a pressure level p of about 0.001 bar by means of a vacuum pump. Various mounting positions are possible for the vacuum pump used. The vacuum pump may for example be connected downstream of a rinsing or service valve or upstream of a switching valve between a cleaning stage and a gas buffer. Alternatively, it is also possible to arrange the delivery unit used as a vacuum pump before the tank inlet valve. The low pressure generated by the vacuum pump in the interior of the gas storage leads to the desorption of impurities, thereby lowering the total pressure in the free storage volume of the gas storage, whereby the partial pressure of the impurities is lowered. By evacuating the gas reservoir and the tendency of pressure equalization, a substantial portion of the contaminants sorbed on the sorbent material are absorbed into the gas phase.

After the evacuation step or the above-outlined heating step, which can optionally be combined with the evacuation step and cycled through, a purge gas from a purge gas reservoir, either in the context of a single use or by providing a circulation pump through the gas storage, in particular the sorbent passed and go through an arranged outside of the gas storage purification stage. The lower the pressure in the gas storage is or the higher the temperature prevailing there, the less number of cycles with respect to evacuation steps or heating steps must be run through. The cleaning stage may optionally be run through several times by using a circulating pump. The purge gas used is preferably an inert gas, such as nitrogen or air, or alternatively a fuel gas, such as pure CH ₄ , in gas storage. As purge gas, all gases are suitable which do not react with the preferred embodiment as MOF. tion material of the gas storage react, so for example, in addition to N ₂ , air and He and natural gas without high boiler. The rinsing of the gas reservoir can also be carried out as part of the refilling of the gas storage.

A heating and / or lowering of the pressure can be used to expel the purge gas from the gas storage. A positive side effect of the passage of the gas storage with the purging gas present as an inert gas is the fact that with the purging gas also dust contamination and liquid droplets can be blown out of the gas storage.

As an alternative to cleaning the sorption of the gas storage and replacement of the sorbent material or the entire gas storage is possible. To replace the sorbent material from the gas storage closable filling and removal openings are provided on the gas storage. The removed gas storage could then be regenerated outside a vehicle, for example.

The cleaning of the sorption of the gas storage can be done via a controller or done manually. By way of a control device which receives the degree of impurities in the purge gas via a signal of a gas quality sensor, the heating device assigned to the gas accumulator can be switched on or off, for example, or the heating power of the heating device associated with the gas accumulator can be regulated. Via the control unit, the cleaning stage can be activated or deactivated in dependence on the signal of the gas quality sensor. In addition, both the tank inlet valve, the shut-off valve between the tank inlet valve and the purge gas reservoir can be opened or closed via the control unit. Furthermore, via the control unit, a delivery unit serving as a vacuum pump can be switched on and off, and a recovery or a return of the purge gas can be activated from an optionally provided gas intermediate storage.

drawing

Reference to the drawing, the invention will be described in more detail.

The drawing shows the interconnection of a gas storage tank, which makes it possible to remove impurities from the sorption material of the gas storage tank. variants

From the illustration according to the drawing, a gas storage 10 is shown. The gas storage 10 is limited by a gas storage wall 12. In the cavity of the gas reservoir 10, a sorption material 18 is accommodated, which is preferably Metal Organic Frameworks (MOF's).

The porous organometallic framework contains at least one at least one metal ion coordinated at least bidentate organic compound. This organometallic framework (MOF) is described, for example, in US Pat. No. 5,648,508, EP-A-0 790 253, M. O-Keeffe et al., J. Sol. State Chem., JJ2 (2000), pages 3 to 20, H. Li et al, Nature 402 (1999), page 276, M. Eddaoudi et al., Topics in Catalysis 9 (1999), pages 105 to 111, B Chen et al., Science 291 (2001), pages 1021 to 1023 and DE-A-101 11 230.

The MOFs according to the present invention contain pores, in particular micro and / or mesopores. Micropores are defined as those having a diameter of 2 nm or smaller and mesopores are defined by a diameter in the range of 2 to 50 nm, each according to the definition as described by Pure Applied Chem. 45_, page 71, in particular on page 79 (FIG. 1976). The presence of micro- and / or mesopores can be checked by means of sorption measurements, these measurements determining the uptake capacity of the organometallic frameworks for nitrogen at 77 Kelvin according to DIN 66131 and / or DIN 66134.

The specific surface area - calculated according to the Langmuir model (DIN 66131, 66134) for a MOF in powder form is preferably more than 5 m ² / g, more preferably more than 10 m ² / g, more preferably more than 50 m ² / g , more preferably more than 500 m ² / g, even more preferably more than 1000 m ² / g and particularly preferably more than 1500 m ² / g. MOF shaped bodies can have a lower specific surface; but preferably more than 10 m ² / g, more preferably more than 50 m ² / g, even more preferably more than 500 m ² / g and in particular more than 1000 m ² / g.

The metal component in the framework of the present invention is preferably selected from Groups Ia, IIa, IHa, IVa to Villa and Ib to VIb. Particularly preferred are Mg, Ca, Sr, Ba, Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Ru, Os, Co, Rh, Ir, Ni , Pd, Pt, Cu, Ag, Au, Zn, Cd, Hg, Al, Ga, In, Tl, Si, Ge, Sn, Pb, As, Sb and Bi. More preferred are Zn, Cu, Mg, Al, Ga, In, Sc, Y, Lu, Ti, Zr, V, Fe, Ni, and Co. In particular, Cu, Zn, Al, Fe, and Co. are particularly preferred. With respect to the ions of these elements, mention is particularly made of Mg ^{2 +} , Ca ²⁺ , Sr ²⁺ , Ba ²⁺ , Sc ³⁺ , Y ³⁺ , Ti ⁴⁺ , Zr ⁴⁺ , Hf ⁴⁺ , V ⁴⁺ , V ³⁺ , V ²⁺ ,

, "3+ m 3+ r ^ 3 + n It 3 + ττ r3 + nt 3+ nt 2+ τ- _> 3+ τ- _> 2+ T- 3 + T-" 2+ τ- _> 3+ τ- _> 2+ / ~ v 3+ / ~ v 2+

Nb, Ta, Cr, Mo, W, Mn, Mn, Re, Re, Fe, Fe, Ru, Ru, Os, Os, Co ^3+, Co ^2+, Rh ^2+, Rh ^+, Ir ^2+, Ir ⁺ , Ni ²⁺ , Ni ⁺ , Pd ²⁺ , Pd ⁺ , Pt ²⁺ , Pt ⁺ , Cu ²⁺ , Cu ⁺ , Ag ⁺ , Au ⁺ , Zn ²⁺ , r C <d A ^ ⁺ , T HJg ² +, AA il3 +, fG ~ ia 3+, TIn ³⁺ , TTll ³⁺ , CSi " ⁴⁺ , CSi" ² +, ^ Ge 4+, G, ^ e 2+, oSn 4+, oSn 2+, TPiUb ⁴⁺ , TP) Ub ²⁺ , AA s ⁵⁺ , AA s ³⁺ , As ⁺ , Sb ⁵⁺ , Sb ³⁺ , Sb ⁺ , Bi ⁵⁺ , Bi ³⁺ and Bi ⁺ .

The term "at least bidentate organic compound" refers to an organic compound containing at least one functional group capable of having at least two, preferably two coordinative, bonds to a given metal ion, and / or to two or more, preferably two, metal atoms, respectively to form a coordinative bond.

Examples of functional groups which can be used to form the abovementioned coordinative bonds are, for example, the following functional groups: CO ₂ H, -CS ₂ H, -NO ₂ , -B (OH) ₂ , -SO ₃ H, Si (OH) _3, -Ge (OH) _3, -Sn (OH) _3, -Si (SH) _4, - Ge (SH) _4, -Sn (SH) _3, -PO ₃ H, ₃ H -AsO , -AsO ₄ H, -P (SH) ₃ , -As (SH) ₃ , -CH (RSH) ₂ , -C (RSH) ₃ -CH (RNH ₂ ) ₂ -C (RNH ₂ ) ₃ , -CH (ROH) ₂ , -C (ROH) ₃ , -CH (RCN) ₂ , -C (RCN) ₃ where, for example, R preferably represents an alkylene group having 1, 2, 3, 4 or 5 carbon atoms, for example a methylene, ethylene , n-propylene, i-propylene, n-butylene, i-butylene, tert-butylene or n-pentylene group, or an aryl group containing 1 or 2 aromatic nuclei such as 2 Cό rings, which may be condensed and independently of one another can be suitably substituted by at least one substituent in each case, and / or independently of one another in each case at least one heteroatom, for example e may contain N, O and / or S. According to likewise preferred embodiments, functional groups are to be mentioned in which the abovementioned radical R not available. In this regard are, inter alia, -CH (SH) _2, -C (SH) _3, -CH (NH ₂₎ _2, - C (NH ₂₎ _3, -CH (OH) _2, -C (OH) _3, -CH (CN) ₂ or -C (CN) ₃ to call.

The at least two functional groups can in principle be bound to any suitable organic compound, as long as it is ensured that the organic compound containing these functional groups is capable of forming the coordinative bond and for preparing the framework material.

Preferably, the organic compounds containing the at least two functional groups are derived from a saturated or unsaturated aliphatic compound or an aromatic compound or an aliphatic as well as an aromatic compound.

The aliphatic compound or the aliphatic portion of the both aliphatic and aromatic compound may be linear and / or branched and / or cyclic, wherein also several cycles per compound are possible. More preferably, the aliphatic compound or the aliphatic portion of the both aliphatic and aromatic compound contains 1 to 15, more preferably 1 to 14, further preferably 1 to 13, further preferably 1 to 12, further preferably 1 to 11 and particularly preferably 1 to 10 C atoms such as, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 C atoms. Methane, adamantane, acetylene, ethylene or butadiene are particularly preferred in this case.

The aromatic compound or the aromatic part of both aromatic and aliphatic compound may have one or more cores, such as two, three, four or five cores, wherein the cores may be separated from each other and / or at least two nuclei in condensed form. Most preferably, the aromatic compound or the aromatic moiety of the both aliphatic and aromatic compounds has one, two or three nuclei, with one or two nuclei being particularly preferred. Independently of each other, furthermore, each core of the compound mentioned may contain at least one heteroatom, such as, for example, N, O, S, B, P, Si, Al, preferably N, O and / or S. More preferably, the aromatic compound or the aromatic portion of the both aromatic and aliphatic compound contains one or two C _ό cores, the two being either separately or in condensed form. In particular, benzene, naphthalene and / or biphenyl and / or bipyridyl and / or pyridyl may be mentioned as aromatic compounds. The at least bidentate organic compound is particularly preferably derived from a di-, tri- or tetracarboxylic acid or its sulfur analogs. Sulfur analogues are the functional groups -C (= O) SH and its tautomer and C (= S) SH, which can be used instead of one or more carboxylic acid groups.

The term "derive" in the context of the present invention means that the at least bidentate organic compound can be present in the framework material in partially deprotonated or completely deprotonated form. Furthermore, the at least bidentate organic compound may contain further substituents, such as -OH, -NH ₂ , - OCH ₃ , -CH ₃ , -NH (CH ₃ ), -N (CH ₃ ) ₂ , -CN and halides.

For example, dicarboxylic acids, such as oxalic acid, succinic acid, tartaric acid, 1,4-butanedicarboxylic acid, 4-oxo-pyran-2,6-dicarboxylic acid, 1,6-hexanedicarboxylic acid, decanedicarboxylic acid, 1,8-heptadecanedicarboxylic acid, are examples of the present invention. 1,9-heptadecanedicarboxylic acid, heptadecanedicarboxylic acid, acetylenedicarboxylic acid, 1,2-benzenedicarboxylic acid, 2,3-pyridinedicarboxylic acid, pyridine-2,3-dicarboxylic acid, 1,3-butadiene-1,4-dicarboxylic acid, 1,4-benzenedicarboxylic acid, Benzenedicarboxylic acid, imidazole-2,4-dicarboxylic acid, 2-methyl-quinoline-3,4-dicarboxylic acid, quinoline-2,4-dicarboxylic acid, quinoxaline-2,3-dicarboxylic acid, 6-chloroquinoxaline-2,3-dicarboxylic acid, 4,4'-diaminophenylmethane-3,3'-dicarboxylic acid, quinoline-3,4-dicarboxylic acid, 7-chloro-4-hydroxyquinoline-2,8-dicarboxylic acid, diimidedicarboxylic acid, pyridine-2,6-dicarboxylic acid, 2-methylimidazole 4,5-dicarboxylic acid, thiophene-3,4-dicarboxylic acid, 2-isopropylimidazole-4,5-dicarboxylic acid, tetrahydropyran-4,4-dicarboxylic acid, perylene-3,9 dicarboxylic acid, perylenedicarboxylic acid, Pluriol E 200-dicarboxylic acid, 3,6-dioxaoctanedicarboxylic acid, 3,5-cyclohexadiene-1,2-dicarboxylic acid, octadicarboxylic acid, pentane-3,3-carboxylic acid, 4,4'-diamino-1, r-diphenyl-3,3'-dicarboxylic acid, 4,4'-diaminodiphenyl-3,3'-dicarboxylic acid, benzidine-3,3'-dicarboxylic acid, 1, 4-bis-

(Phenylamino) -benzene-2,5-dicarboxylic acid, 1-dinaphthyl-5,5'-dicarboxylic acid, 7-chloro-8-methylquinoline-2,3-dicarboxylic acid, 1-anilinoanthraquinone-2,4'-dicarboxylic acid , Polytetrahydrofuran-250-dicarboxylic acid, 1,4-bis (carboxymethyl) -piperazine-2,3-dicarboxylic acid, 7-chloroquinoline-3,8-dicarboxylic acid, 1- (4-carboxy) -phenyl-3 - (4-chloro) -phenylpyrazolin-

4,5-dicarboxylic acid, 1, 4,5,6,7,7, hexachloro-5-norbornene-2,3-dicarboxylic acid, phenylindane-1-carboxylic acid, 1,3-dibenzyl-2-oxo-imidazolidine-4,5 dicarboxylic acid, 1, 4-

Cyclohexanedicarboxylic acid, naphthalene-1, 8-dicarboxylic acid, 2-benzoylbenzene-1,3-dicarboxylic acid, 1,3-dibenzyl-2-oxo-imidazolidine-4,5-cis-dicarboxylic acid, 2,2'-biquinoline-4,4'- dicarboxylic acid, pyridine-3,4-dicarboxylic acid, 3,6,9-trioxaundecanedicarboxylic acid, O-hydroxybenzophenone dicarboxylic acid, Pluriol E 300 dicarboxylic acid, Pluriol E 400 dicarboxylic acid, Pluriol E 600 dicarboxylic acid, pyrazole-3,4-dicarboxylic acid, 2,3-pyrazine dicarboxylic acid, 5,6-dimethyl-2,3-pyrazine dicarboxylic acid, 4,4'-

Diaminodiphenyl ether diimide dicarboxylic acid, 4,4'-diaminodiphenylmethanediimide dicarboxylic acid, 4,4'-diaminodiphenylsulfonediimide dicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,3-adamantanedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, 8-methoxy-2,3-benzoic acid naphthalenedicarboxylic acid, 8-nitro-2,3-naphthalenecarboxylic acid, 8-sulfo-2,3-naphthalenedicarboxylic acid, anthracene-2,3-dicarboxylic acid, 2 ', 3'-diphenyl-p-terphenyl-4,4'-dicarboxylic acid, diphenyl ether 4,4'-dicarboxylic acid, imidazole-4,5-dicarboxylic acid, 4 (1 H) -oxothiochromene-2,8-dicarboxylic acid, 5-tert-butyl-1, 3-benzenedicarboxylic acid, 7,8-quinolinedicarboxylic acid, 4, 5-imidazoledicarboxylic acid, 4-cyclohexane-1,2-dicarboxylic acid, hexatriacontanedicarboxylic acid, tetradecanedicarboxylic acid, 1,7-heptadicarboxylic acid, 5-hydroxy-1,3-benzenedicarboxylic acid, pyrazine-2,3-dicarboxylic acid, furan-2,5 dicarboxylic acid, 1-nonene-6,9-dicarboxylic acid, eicosendicarboxylic acid, 4,4'-dihydroxydiphenylmethane-3,3'-dicarboxylic acid, 1-amino-4-methyl- 9,10-dioxo-9,10-dihydroanthracene-2,3-dicarboxylic acid, 2,5-pyridinedicarboxylic acid, cyclohexene-2,3-dicarboxylic acid, 2,9-dichlorofluorubin-4,1-dicarboxylic acid, 7-chloro-3 methylquinoline-6,8-dicarboxylic acid, 2,4-dichlorobenzophenone-2 ', 5'-dicarboxylic acid, 1,3-benzenedicarboxylic acid, 2,6-pyridinedicarboxylic acid, 1-methylpyrrolo-3,4-dicarboxylic acid, 1-benzyl-1 H-pyrrole-3,4-dicarboxylic acid, anthraquinone-1, 5-dicarboxylic acid, 3, 5-pyrazoldicarboxylic acid, 2-nitrobenzene-1, 4-dicarboxylic acid, heptane-1, 7-dicarboxylic acid, cyclobutane-1,1-dicarboxylic acid 1 , 14-tetradecanedicarboxylic acid, 5,6-dehydronorbornane-2,3-dicarboxylic acid or 5-ethyl-2,3-pyridinedicarboxylic acid,

Tricarboxylic acids such as

2-hydroxy-l, 2,3-propanetricarboxylic acid, 7-chloro-2,3,8-quinoline tricarboxylic acid, 1,2,4-benzenetricarboxylic acid, 1, 2,4-butanetricarboxylic acid, 2-phosphono-1, 2,4- butanetricarboxylic acid, 1, 3,5-benzenetricarboxylic acid, 1-hydroxy-1,2,3-propanetricarboxylic acid, 4,5-dihydro-4,5-dioxo-1H-pyrrolo [2,3-F] quinoline 2,7,9-tricarboxylic acid, 5-acetyl-3-amino-6-methylbenzene-1, 2,4-tricarboxylic acid, 3-amino-5-benzoyl-6-methyl-1-bis-1,2,4-tricarboxylic acid acid, 1,2,3-propanetricarboxylic acid or aurintricarboxylic acid,

or tetracarboxylic acids such as

1, 1-dioxideperylo [1, 12-BCD] thiophene-3, 4,9,10-tetracarboxylic acid, perylenetetracarboxylic acids such as perylene-3,4,9,10-tetracarboxylic acid or perylene-1,15-sulfone-3, 4,9,10-tetracarboxylic acid,

Butanetetracarboxylic acids such as 1,2,3,4-butanetetracarboxylic acid or meso-1,2,3,4- Butanetetracarboxylic acid, decane-2,4,6,8-tetracarboxylic acid, 1,4,7,10,13,16-

Hexaoxacyclooctadecane-2,3,11,12-tetracarboxylic acid, 1, 2,4,5-benzene tetracarboxylic acid,

1, 2, 11, 12-dodecantetracarboxylic acid, 1, 2,5,6-hexanetetracarboxylic acid, 1, 2,7,8-octane-tetracarboxylic acid, 1, 4,5,8-naphthalenetetracarboxylic acid, 1, 2, 9, 10 Decantetracarboxylic acid, benzophenone tetracarboxylic acid, 3,3 ', 4,4'-benzophenone tetracarboxylic acid, tetrahydrofuran-tetracarboxylic acid or cyclopentanetetracarboxylic acids such as cyclopentane-1,2,3,4-tetracarboxylic acid

to call.

Very particular preference is given to using at least mono-, di-, tri-, tetra- or higher-nuclear aromatic di-, tri- or tetracarboxylic acids, where each of the cores can contain at least one heteroatom, where two or more nuclei have identical or different heteroatoms may contain. For example, preference is given to monocarboxylic dicarboxylic acids, monocarboxylic tricarboxylic acids, monocarboxylic tetracarboxylic acids, dicercaric dicarboxylic acids, dicercaric tricarboxylic acids, dicercaric tetracarboxylic acids, tricyclic dicarboxylic acids, tricarboxylic tricarboxylic acids, tricarboxylic tetracarboxylic acids, tetracyclic dicarboxylic acids, tetracyclic tricarboxylic acids and / or tetracyclic tetracarboxylic acids. Suitable heteroatoms are, for example, N, O, S, B, P, Si, Al. Preferred heteroatoms here are N, S and / or O. A suitable substituent in this regard is, inter alia, -OH, a nitro group, an amino group or an alkyl to name or alkoxy.

Especially preferred as the at least bidentate organic compounds are acetylenedicarboxylic acid (ADC), benzenedicarboxylic acids, naphthalenedicarboxylic acids, biphenyldicarboxylic acids such as 4,4'-biphenyldicarboxylic acid (BPDC), bipyridine dicarboxylic acids such as 2,2'-bipyridinedicarboxylic acids such as 2,2 '-Bipyridin-

5,5-dicarboxylic acid, benzene tricarboxylic acids such as 1,2,3-benzenetricarboxylic acid or 1,3,5-benzenetricarboxylic acid (BTC), adamantane tetracarboxylic acid (ATC), adamantane dibenzoate (ADB) benzene tribenzoate (BTB), methanetetrabenzoate (MTB), adamantane trenches - zoate or dihydroxyterephthalic acids such as 2,5-dihydroxyterephthalic acid

(DHBDC) used.

Isophthalic acid, terephthalic acid, 2,5-dihydroxyterephthalic acid, 1,2,3-benzenetricarboxylic acid, 1,3,5-benzenetricarboxylic acid or 2,2-bipyridine-5,5'-dicarboxylic acid are very particularly preferably used. In addition to these at least bidentate organic compounds, the MOF may also comprise one or more monodentate ligands.

Suitable solvents for the preparation of the MOF include ethanol, dimethylformamide, toluene, methanol, chlorobenzene, diethylformamide, dimethyl sulfoxide, water, hydrogen peroxide, methylamine, sodium hydroxide, N-methylpolidone ether, acetonitrile, benzyl chloride, triethylamine, ethylene glycol and mixtures thereof. Further metal ions, at least bidentate organic compounds and solvents for the preparation of MOF are described inter alia in US Pat. No. 5,648,508 or DE-A 101 11 230.

The pore size of the MOF can be controlled by choice of the appropriate ligand and / or the at least bidentate organic compound. Generally, the larger the organic compound, the larger the pore size. The pore size is preferably from 0.2 nm to 30 nm, and the pore size is particularly preferably in the range from 0.3 nm to 3 nm, based on the crystalline material.

In a MOF shaped body, however, larger pores also occur whose size distribution can vary. Preferably, however, more than 50% of the total pore volume, in particular more than 75%, of pores having a pore diameter of up to 1000 nm is formed. Preferably, however, a majority of the pore volume is formed by pores of two diameter ranges. It is therefore further preferred if more than 25% of the total pore volume, in particular more than 50% of the total pore volume, is formed by pores which are in a diameter range of 100 nm to 800 nm and if more than 15% of the total pore volume, in particular more than 25% of the total pore volume is formed by pores in a diameter range of up to 10 nm. The pore distribution can be determined by means of mercury porosimetry.

The gas reservoir 10 according to the drawing has a filling opening 14 and a removal opening 16. The filling opening 14 or the removal opening 16 can exchange the sorption material 18 present in the gas storage 10, to which the gaseous fuel, for example CH _{4 accumulates} as a main component of natural gas when filling the gas reservoir 10. As gaseous fuel for filling the gas reservoir 10, preference is given to using natural gas or city gas. The gas storage 10 according to the drawing is associated with a heating device 20 arranged outside in this embodiment variant. The heater 20 communicates with the interior of the gas reservoir 10 via a Supply line 22 and a discharge line 24 in conjunction; In the circulation circuit 20, 22, 24, a heat transfer medium, such as water, is moved.

The gas reservoir 10 is assigned a tank inlet valve 26, which comprises a shut-off valve and a throttle valve. Between the tank inlet valve 26 and the inlet side of the gas reservoir 12 extends a filler neck 32. At the tank inlet valve 26, a first shut-off valve 28 is connected. The shut-off valve 28 controls the inflow of a purge gas, which may be, for example, nitrogen or air from a Spülgasreservoir 30. Except N ₂ or air as purge gas, all gases that are not with the Sorp- tion material 18 (MOF ), for example, He, CH ₄ , and natural gas without high boiler. In the simplest case, the purge gas reservoir 30 consists of a gas cylinder, which is connected to the tank inlet valve 26 via the first shut-off valve 28.

On the outlet side of the gas reservoir 12 is a tank removal valve 34, from which extends a consumption line 36 to the internal combustion engine of a vehicle operated with gaseous fuel. Before the tank removal valve 34, a purge valve 38 branches off. Via the flushing valve 38, the contaminants desorbed from the interior of the gas reservoir 10 or its sorption material 18 reach a first switching valve 42. Between the flushing valve 38 and the first switching valve 42, between which the contaminated flushing gas 44 flows, a gas quality sensor 40 is received. Via the gas quality sensor 40, the degree of contamination of the purge gas with impurities 44 can be determined. A corresponding information is transmitted from the gas quality sensor 40 via a signal line 76 to a control unit 60.

From the first switching valve 42 can be branched both to a cleaning stage, as well as to a gas buffer 50, a recovery or a gas recirculation, which can optionally be connected to the gas storage 12.

From the cleaning stage 48, the purge gas purified in the purification stage 48 flows to a second changeover valve 52. At the second switching valve 52, a supply line from the intermediate gas storage 50, a recovery or a gas recirculation can be connected. The second switching valve 52 may be followed by a delivery unit 54, which is preferably a vacuum clean pump. From the control unit 60, the delivery unit 54 can be controlled via a control line 68, while the gas buffer 50 or the recovery or the return can be activated or deactivated via a control line 70 extending from the control unit 60. The delivery unit 54 may be accommodated on the one hand between the gas quality sensor 40 and the first changeover valve 42 and on the other hand also between the purge valve 38 and the gas quality sensor 40. It is also possible, as shown in the drawing, to position the delivery unit 54 serving as a vacuum pump behind the second changeover valve 52 or to connect it upstream of the tank inlet valve 26.

In addition, the tank inlet valve 26 is opened or closed via the control unit 60 via the control line 62; via a drive line 64 which extends from the controller 60 to the first shut-off valve 28, the actuation thereof, i. the opening or closing of the first shut-off valve 28, to which the Spülgasreservoir 30 is connected.

Downstream of the delivery unit 54 is a trigger valve 56, in front of which a supply line to the tank inlet valve 26 branches off.

The trigger valve 56, which is also activated or deactivated by a control line 66 from the control unit 60, a trigger 58 is connected downstream, via which the purge gas with impurities 44, bypassing the cleaning stage 48, from the gas buffer 50 with open second switching valve 52 via the Delivery unit 54 can be drained from the system. The sequence of the purification process proposed according to the invention is as follows:

First, the gas storage 10 is emptied so far that in this still a pressure level of <3 bar, preferably <1, 5 bar and more preferably ambient pressure level prevails.

The cleaning process, as described in more detail below, is preferably carried out within the scope of maintenance intervals of the vehicle in workshops. The gas storage 10 interconnected with the circuit shown in the drawing.

The removal valve 36 to the consumer, such as in the case of automotive applications of the internal combustion engine of a motor vehicle, is closed. Thereafter, the opening of the purge valve 38, so that the current residual content in the gas storage 12 remaining gaseous fuel depending on the version, for example, after opening the first change-over valve 42 in the intermediate gas storage 50 can be stored. From the gas intermediate store 50, both a return of the volume of the gaseous fuel stored there into the gas storage 12 via second changeover valve 52 and Tank inlet valve 26 take place, as well as a thermal utilization when opening the trigger valve 56 and outflow of the gas in the trigger 58th

An emptying of the still remaining in the gas storage 12 supply of gaseous fuel can also be done by opening the tank inlet valve 26 in the direction of the trigger 58. If the trigger valve 56 is also opened, the residual gas volume in the gas reservoir 12 can flow out via the open tank inlet valve 26 and the opened trigger valve 56 into the trigger 58 and be thermally utilized there.

When emptying the gas reservoir 12, the service valve 38 is closed. If necessary, flammable gases and impurities are rendered harmless before being emitted into the environment.

Depending on the degree of contamination and effectiveness and depending on the sorption material 18 used, various cleaning steps are possible in repeated cycles and combined with one another.

The subsequent individual steps of the method proposed according to the invention can be carried out both automatically with the aid of the control unit 60 and manually.

Removal of contaminants from the sorbent material 18 received within the gas reservoir 12 may be accomplished by turning on the heater 18. The in the supply line 22 and in the discharge line 24 by the heater 20 and the gas accumulator 12 Inne- re circulating heat transfer medium heats the tank up to a maximum temperature T _max of from about 350 ⁰ C. If the sorption material 18 within the gas reservoir 12 is MOF, the maximum temperature T _{max is} preferably 200 ^° C. At low pressure within the gas reservoir 10, the heating of the sorption material 18 leads to a desorption of impurities whose desorption temperature lies below the respective one Maximum temperature T _max is.

The gas storage 10 may also be evacuated either alternatively to the heating step - as described above - or combined with the heating step with a vacuum pump, whereby within the gas reservoir 12, a pressure p of 0.001 bar is generated. The vacuum pump can have various mounting positions. If a vacuum in the gas storage 10, such as a technical vacuum of the vacuum pump via the vacuum pump Example p = 0.001 bar, produced, this low pressure leads to the desorption of impurities from the sorbent material 18, since with the lowering of the total pressure in the free storage volume of the gas storage 12 and the partial pressure of the impurities is lowered. The pursuit of equilibrium means that part of the sorbent adsorbed on the sorption material 18 can be desorbed into the gas phase and expelled from the gas storage 12 by means of the purge gas 46.

The purge gas 46, which flows via the Spülgasreservoir 30, the first shut-off valve 28 and the tank inlet valve 26 via the filler plug 32 into the interior of the gas storage 12, can be used both once or be used with the interposition of a circulation pump after passage of the cleaning stage 48 several times or be driven through the gas storage 12 in several cleaning cycles. Preferably, a temperature control of the purge gas 46, which can be done for example via the heater 20. The purge gas 46 may be inert gas such as nitrogen or air or pure CH ₄ , He or natural gas without high boiler. The expulsion of the purge gas 46 with impurities from the interior of the gas storage 12 is effected by heating the gas storage interior via the heater 20 and / or lowering the pressure within the gas reservoir 10 by the already mentioned vacuum pump. A positive side effect of the passage of the gas storage 12 with purge gas 46 is the fact that from the interior of the gas storage 10 as well as from the surface of the sorbent material 18 also dust contamination and liquid drops can be blown out.

Since the tank removal valve 34 is closed at the outflow side of the gas reservoir 10 and the purge valve 38 is opened, the purge gas 44 laden with impurities flows via the purge valve 38 to the first changeover valve 42. The gas quality sensor 40 generates a signal corresponding to the degree of contamination of the laden purge gas 44 and transmits this via the signal line 76 to the control unit 60 in the case of automated cleaning of the sorbent material 18 of the gas reservoir 10th

Via the control unit 60, the cleaning stage 48 can be activated via signal line 74. In accordance with the switching position of the first switching valve 42, the flushing gas 44 loaded with impurities can both be supplied to the cleaning stage 48 and fed to the intermediate gas reservoir 50 at the first switching valve 42. The intermediate gas storage 50 is optionally present. If the flushing gas 44 loaded with impurities passes through the cleaning stage 48, the impurities are removed from the laden flushing gas 44. removed. The purified purge gas 46 flows to the second switching valve 52. From the second switching valve 52, the purified purge gas 46 is pumped in the direction of the trigger 58. If the trigger valve 56 is open, the purified purge gas 46 flows into the trigger 58. If the trigger valve 56 is closed, then the purified purge gas 46 flows to the tank inlet valve 26 and can pass into the interior of the gas reservoir 10 again in a further cleaning cycle via the filler neck 32 ,

In addition to the cleaning stage 48, the optionally existing intermediate gas reservoir 50 and the delivery unit 54 can be controlled via the control unit 60 via the signal line 74. From the control unit 60 also extend the signal line 72 to the heater 20 and drive lines, such as the Ansteuerleitung 62 to the tank inlet valve 26, as the Ansteuerleitung 64 to the check valve 28 and the Ansteuerleitung 66 to open or close the trigger valve 56th

The emptying of the gas storage 12 can take place both after closing the tank removal valve 34 and the opening of the purge valve 38 in the optionally existing gas buffer 50 and from this via the second switching valve 52 and open trigger valve 56 in the trigger 58, where the gaseous fuel, for example a thermal utilization can be supplied. Alternatively, the emptying of the gas reservoir 10 can take place even with the purge valve 38 closed and the tank retainer valve 34 closed via the open tank inlet valve 26 with the first shut-off valve 28 closed and the discharge valve 56 open directly into the vent 58. The pressure level in the gas reservoir 10 after emptying is <3 bar, preferably <1, 5 bar and particularly preferably at ambient pressure level.

The desorption of contaminants from sorbent material 18 of gas reservoir 10 by heating sorption material 18 via heater 20 may be one or more times depending on the degree of contamination of sorbent material 18. The evacuation of the interior of the gas reservoir 10 by means of the vacuum pump can be one or more times, desorb on the low pressure within the gas storage 12, the contaminants from the sorbent 18, as with the reduction of the total pressure in the free storage volume of the gas storage 10 and the Partialdruck the impurities is lowered. Further, the heating and evacuation of the gas storage 10 can be made combined with each other. The heater 20 may - as mentioned above - be used for temperature control of the purge gas 46, which flows to the interior of the gas reservoir 10 via the first, open shut-off valve 28 and the open tank inlet valve 26. The heating of the sorption material 18, the generation of the negative pressure in the gas reservoir 10 via the vacuum pump and the purging of the flushing gas 46 by heating or lowering the pressure can be repeated several times or combined or cyclic.

If the degree of contamination of the sorption material 18 by foreign substances after passing through the process steps proposed according to the invention is so high that its storage capacity has been improved only insufficiently, the sorption material 18 can be exchanged via the filling opening 14 provided on the gas storage 10 or the removal opening 16 formed on the gas storage 10 , Alternatively, the gas storage 10 - for example, in applications in the automotive sector - are completely removed from the vehicle, a new gas storage 10 with sorption material 18 (MOF) are installed in this and the built-up from the motor vehicle gas storage 10 are regenerated outside the vehicle.

Claims

claims

1. A method for cleaning a gas reservoir (10), in particular a sorption storage in which a sorption material (18) is located, with the following process steps:

a) the emptying of the gas reservoir (10) via a tank inlet valve (26) in a trigger (58) or via a flush valve (38) in a gas buffer (50) and at least one of the method steps bi) the heating of the sorbent material (18) via a Heating device (20) b ₂ ) generating a negative pressure in the gas reservoir (10) for desorption of impu- rities from the sorption material (18) by means of a delivery unit (54).

2. The method according to claim 1, characterized in that according to step a), a bleed valve (34) is closed and the flush valve (38) is opened.

3. The method according to claim 1, characterized in that according to step bi) the heating of the gas reservoir (10) for desorption of impurities from the sorbent material (18) to a maximum temperature T _max of 350 ⁰ C, preferably 200 ⁰ C or for expelling the Impurities laden purge gas (44) takes place.

4. The method according to claim 1, characterized in that according to step bi) or b ₂ ) of the gas storage (10) is rinsed at least once with pure or purified or inert purge gas.

5. The method according to claim 4, characterized in that laden with impurities flushing gas (44) of a cleaning stage (48) is supplied.

6. The method according to claim 4, characterized in that with impurities loaded purge gas (44) via the heating device (20) tempered and dried.

7. The method according to claim 4, characterized in that desorbed with desorbed impurities flushed purge gas (44) by heating the gas reservoir (10) via the heater (20) and / or lowering the pressure in the gas reservoir (10) by means of the delivery unit (54) expelled becomes.

8. The method according to claim 1, characterized in that the process steps bi) or 1) ₂ ) cyclically or repeatedly repeated or combined.

9. The method according to claim 1, characterized in that the sorption material (18) of the gas reservoir (10) via filling or removal openings (14, 16) is replaced at the gas storage (10).

10. The method according to claim 1, characterized in that according to step a) from the gas storage (10) bottled, combustible gas is rendered inert.

11. A device for cleaning a gas reservoir (10), in particular a Sorptionsspeichers in which a sorption material (18) is received, with a tank inlet valve (26) and a tank removal valve (34), characterized in that the gas supply (10) a Heating device (20) and / or a delivery unit (54) for generating a negative pressure in the gas reservoir (10) is associated.

12. The device according to claim 11, characterized in that the gas reservoir (10) via a flush valve (38) in a gas buffer (50) or via the tank inlet valve (26) in a trigger (58) can be emptied.

13. The apparatus according to claim 11, characterized in that the gas accumulator (10) is associated with a flushing valve (38) and a first switching valve (42) for acting on a cleaning stage (48) loaded with impurities flushing gas (44).

14. The apparatus according to claim 13, characterized in that between the purge valve (38) and the first switching valve (42) a gas quality sensor (40) is arranged, with which the degree of contamination of the laden with impurities purge gas (44) is determined.