WO2009071436A1

WO2009071436A1 - Method for storing gaseous hydrocarbons

Info

Publication number: WO2009071436A1
Application number: PCT/EP2008/065692
Authority: WO
Inventors: Ulrich Mueller; Frank Poplow; Markus Schubert; Jan-Michael Graehn; Werner Gruenwald; Ian Faye
Original assignee: Robert Bosch Gmbh; Basf Aktiengesellschaft
Priority date: 2007-12-06
Filing date: 2008-11-17
Publication date: 2009-06-11
Also published as: DE102007058673B4; DE102007058673A1

Abstract

The invention relates to a method for storing gaseous hydrocarbons in a sorption reservoir (5). The temperature of the stored hydrocarbons when the sorption reservoir (5) is full is lower than room temperature and higher than the evaporation temperature of the hydrocarbon. The invention also relates to a device for storing gaseous hydrocarbons, comprising a sorption reservoir (5) that is isolated in relation to the surroundings. The sorption reservoir (5) contains zeolith, activated carbons or metal-organic framework compounds.

Description

description

title

Method for storing gaseous hydrocarbons

State of the art

The invention relates to a method for storing gaseous hydrocarbons in a Sorptionsspeicher. Furthermore, the invention relates to a device for storing gaseous hydrocarbon substances according to the preamble of claim 10.

For the storage of gaseous hydrocarbons compressed gas tanks are generally used today. These can be used both in stationary applications, e.g. for heating buildings, or in mobile applications, e.g. used in gas-powered vehicles. With regard to the mobile applications of compressed gas tanks, these are generally designed for a system pressure of 200 bar and are installed in a gaseous fuel-powered motor vehicle. The storage is usually carried out at ambient temperature. Disadvantage of compressed gas tanks for the storage of gaseous hydrocarbons is that particular safety requirements are made especially for use in motor vehicles.

In addition to pressure accumulators, there is currently a tendency to use sorption accumulators. Sorption reservoirs generally contain a highly porous material, e.g. a MOF (Metal Organic Framework) with a high inner surface. The gas is absorbed by the highly porous material and stored thereby. Sorption reservoirs are currently particularly, e.g. from US Pat. No. 6,748,748, known for hydrogen.

Disclosure of the invention

Advantages of the invention

In the inventive method for storing gaseous hydrocarbons in a Sorptionsspeicher the temperature of the stored hydrocarbon is at Closed sorption reservoir is less than room temperature and greater than the evaporation temperature of the hydrocarbon. The temperature is preferably for filling the memory and for storing the gaseous hydrocarbon in a range from - 196 ° C to -23 ° C, more preferably in a range of -196 ° C to -50 ⁰ C and particularly in the range of -196 ° C to -75 ° C.

A sorption reservoir generally contains a highly porous material, e.g. a MOF (Metal Organic Framework). Other suitable highly porous materials for storing the gaseous hydrocarbon are e.g. Zeolites and activated carbon.

The fact that the temperature of the stored hydrocarbon is reduced when the sorption storage is filled, the storage capacity of the sorbent material can be increased. More hydrocarbon can be absorbed by the sorption reservoir. The fact that the temperature is kept greater than the evaporation temperature of the hydrocarbon, it is avoided that the hydrocarbon condenses in the sorption. The hydrocarbon is still present in gaseous form.

In a preferred variant of the method, the temperature of the hydrocarbon when the sorption reservoir is charged is less than or equal to the temperature of the stored hydrocarbon when the sorption reservoir is filled. As a result, the energy requirement for cooling the hydrocarbon can be reduced in the sorption storage since it no longer has to be cooled down to storage temperature. In addition, the maximum storage capacity of the sorbent material is already achieved when the sorption accumulator is charged. Another advantage of filling the sorption reservoir with already cooled hydrocarbon is that higher-boiling constituents of the gaseous hydrocarbon condense out before the sorption reservoir is charged and thus do not enter the sorption reservoir. In this way it is avoided that the sorption storage is contaminated by heavy boiling components of the gaseous hydrocarbons and in this way the storage capacity decreases over time.

Gaseous hydrocarbons in the context of the present invention are, in particular, C 1 -C 4 -alkanes, C 2 -C 4 -alkenes and C 2 -C 3 -alkynes. Particularly preferred hydrocarbons are natural gas, methane, ethane, propane and butane. And more preferably, the gaseous hydrocarbon is selected from natural gas or methane.

In order to be able to keep the temperature in the sorption storage, it is preferred if the sorption storage is cooled to control the temperature of the gaseous hydrocarbon. The cooling medium used is dependent on the temperature to which the sorption is to be cooled. In particular, suitable as a coolant, for example, liquid nitrogen.

Furthermore, it is preferred if the sorption storage is enclosed by an insulation. The insulation prevents the sorption storage from being warmed up by the environment. In particular, in previously cooled hydrocarbons, it is possible in this way, to use for cooling only little energy. With a particularly good insulation, it may even be possible to completely dispense with the cooling.

In a preferred variant of the method, in order to empty the sorption reservoir, the temperature in the sorption reservoir is increased with decreasing gas content until a maximum permissible temperature is reached so that a predetermined minimum pressure in the sorption reservoir is not undershot. The maximum allowable temperature may be for removal above the temperature to infest the storage and to store the gaseous hydrocarbon.

Increasing the temperature decreases the storage capacity of the sorption reservoir. In this way, more and more gas is released. The maximum permissible temperature, up to which the sorption reservoir is heated, is selected so that only a small proportion of gas remains in the sorption reservoir.

The predetermined minimum pressure depends on the consumer who is to be supplied with the gas from the sorption storage. For example, e.g. when using the Sorptionsspeicher in motor vehicles, a minimum pressure required to provide at predetermined valve cross-sections nor the desired gas mass can. This is necessary to achieve the desired burning power. Below the minimum pressure, losses in performance must be accepted or it is possible that the gas metering valves will no longer open. Gas consumers in the vehicle are e.g. the internal combustion engine in gas-powered internal combustion engines or a fuel cell.

By increasing the temperature when emptying the Sorptionsspeichers the usable tank capacity is significantly increased, whereby a reduced installation space of the tank can be realized with the Sorptionsspeicher or a greater range when used in the vehicle. In addition, the maximum power, that is, a constant gas pressure is available until the tank is substantially empty. -A-

In a first embodiment, the temperature is gradually increased. In this case, each gas is removed at a constant temperature until reaching a predetermined setpoint for the pressure and upon reaching the setpoint, the temperature is increased until a predetermined upper pressure limit is reached. Due to the decreasing sorption capacity of the sorption reservoir as the temperature increases, the pressure in the tank increases due to the increase in temperature. Therefore, when increasing the temperature, make sure that the maximum permitted tank pressure is not exceeded. Excessive pressure could otherwise cause damage to the tank and possibly even rupture of the tank. Especially at higher temperatures, it is necessary to carry out only small temperature increases, since even with small temperature increases, a large increase in pressure occurs. At low temperatures, as they are at the beginning of the removal process and at strongly cooled Sorptionsspeicher, even larger temperature increases only lead to a small increase in pressure.

In order to avoid that the pressure during heating exceeds the maximum permissible pressure of the tank, it is therefore preferred that the predetermined upper pressure limit corresponds to the maximum permissible storage pressure.

Since falling below the predetermined minimum pressure, e.g. leads to a decrease in performance of the gas-powered internal combustion engine or fuel cell, it is preferred that the predetermined desired value for the pressure assumes a value which is between the predetermined minimum pressure and the maximum permissible storage pressure. This ensures that the pressure during gas extraction does not fall below the specified minimum pressure. The upper limit of the range is chosen so that the Sorptionsspeicher the largest possible amount of gas at the temperature reached can be removed.

By gradually increasing the temperature, a comparatively simple two-stage control is possible.

The heating of the Sorptionsspeichers done for example by a heater which is arranged in the tank. The heating can be done for example by heat exchange with a heating medium. Furthermore, however, it is also possible that the heating is carried out, for example, with electrical heating elements. Alternatively, however, heating is also possible by targeted interruption of the heat insulation of the tank. The targeted interruption of thermal insulation can be achieved for example by thermal bridges, which are preferably switchable. When heating the tank with a heating medium is usually a liquid

Heating medium used. This is cooled by the heating of the tank. The thus cooled heating medium can be e.g. to use the temperature of the interior of a motor vehicle, in which the inventive method for controlling the removal of the gas from the Sorptionsspeicher is used.

In an alternative embodiment, when a predetermined pressure has been reached, the temperature in the sorption reservoir is increased when gas is withdrawn such that the pressure remains substantially constant until a predetermined maximum permissible temperature is reached. In order to achieve the most complete emptying of the tank, it is preferred if the predetermined pressure, from which the temperature in the sorption tank is increased, is substantially equal to the predetermined minimum pressure. Substantially equal to the predetermined minimum pressure also means in this case that the predetermined pressure in the range between the minimum pressure and a pressure which is at most 10% greater than the predetermined minimum pressure is.

In contrast to the stepwise increase of the temperature, a greater control effort is required in the temperature control, in which the pressure remains substantially constant.

The sorption can be removed as long as gaseous hydrocarbon with the specified nominal power until the maximum allowable temperature and the predetermined minimum pressure are reached. The maximum permissible temperature is determined in such a way that as complete as possible emptying of the sorption storage is achieved in order to fully exploit the capacity of the Sorptionsspeichers can. The maximum permissible temperature can also be above the bypass temperature.

The invention further relates to a device for storing gaseous hydrocarbons, comprising a sorption storage, which is isolated from the environment, wherein the sorption storage zeolites, activated carbon or organometallic metal framework (MOF) contains.

The isolation of the sorption storage unit ensures that only a small amount of heat is absorbed from the surroundings and thus the carbon hydrogen stored in the sorption storage unit heats up only slowly due to the absorption of heat from the environment. This minimizes the energy required to cool the gaseous hydrocarbon. Zeolites, activated carbon or MOFs are particularly suitable for the sorption of gaseous hydrocarbons. When the gaseous hydrocarbon is natural gas or methane, in particular MOFs are suitable as storage media.

In order to cool the gaseous hydrocarbons stored in the sorption storage, it is preferred if the sorption storage comprises a cooling device. Any suitable cooling device known to those skilled in the art is suitable here. Furthermore, it is also possible that e.g. Channels are formed in the sorption reservoir which are flowed through by a cooling medium. The channels may e.g. be formed in the form of a coil, which is contained in the sorption. As a coolant, as already described above, e.g. liquid nitrogen.

The device according to the invention preferably also detects a control system with which the temperature increase in the sorption reservoir when removing gas can be controlled in such a way that a predetermined minimum pressure is not undershot until a maximum permissible temperature is reached. By the control device, it is possible to increase the temperature during gas removal in order to achieve the most complete removal of the gas from the Sorptionsspeicher. The regulation can, as described above, either take place in such a way that the temperature is increased stepwise or alternatively the temperature is increased such that the pressure remains substantially constant during the temperature increase.

In order to heat the sorption storage with the gaseous hydrocarbon contained therein, it is preferred if the device further comprises a heating element with which the sorption storage can be heated. The heating element is e.g. a heater, which is arranged in the tank. In this case, the heating takes place e.g. by heat exchange with a heating medium. Alternatively, however, it is also possible that e.g. electrical heating elements are used.

In addition to the use of a heating element, it is also possible that the cooling device is also used for heating. In this case, the cooling medium, which was previously used for cooling the Sorptionsspeichers and the gaseous hydrocarbon contained therein, heated, whereby the temperature in the Sorptionsspeicher is increased.

In order to infiltrate and empty the sorption reservoir, it is possible, on the one hand, for a connection to be provided with a valve via which gas is first introduced into the sorptive reservoir. filled in memory. As soon as the sorption reservoir is completely filled, the gas can also be removed again via the same connection. In an alternative embodiment, however, two separate terminals are provided. One port for infilling the sorption reservoir and a second port for removing gas from the sorptive reservoir. The two connections are particularly advantageous when the sorption is used in a vehicle. In this way, the Sorptionsspeicher can be infected via an inlet nozzle with gas. For this purpose, the inlet nozzle ends preferably on the outside of the body of the vehicle, in order to allow easy filling of the tank. The gas can be removed again via a second connection. For this purpose, the second connection is connected, for example, to the internal combustion engine in a gas-operated internal combustion engine or to the fuel cell when the vehicle is operated with a fuel cell.

Brief description of the drawings

Embodiments of the invention are illustrated in the drawings and explained in more detail in the following description.

Show it:

1 shows a device according to the invention for storing a gaseous hydrocarbon,

FIG. 2 shows the method for withdrawing methane in a first embodiment in a storage capacity pressure diagram,

Figure 3 shows the inventive method for removal of methane in a second

Embodiment in a storage capacity pressure diagram.

Embodiments of the invention

FIG. 1 schematically shows a device according to the invention for storing a gaseous hydrocarbon.

A device 1 for storing a gaseous hydrocarbon comprises a tank 3, which contains a sorption storage 5. The sorption storage 5 is preferably a porous organometallic framework compound (MOF). Organometallic framework compounds are described, for example, in US Pat. No. 5,648,508, EP-A 0 790 253, M. O-Keeffe et al., J. Sol. State Chem., 152 (2000), pages 3 to 20, H. Li et al., Nature 402 (1999), page 276, M. Eddaoudi et al., Topics in Catalysis 9 (1999), 105-10 111, 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, especially 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⁺ , Nb ³⁺ , Ta ³⁺ , Cr ³⁺ , Mo ³⁺ , W ³⁺ , Mn ³⁺ , Mn ²⁺ , Re ³⁺ , Re ²⁺ , Fe ³⁺ , Fe ²⁺ , Ru ³⁺ , Ru ²⁺ , Os ^{3 +} , Os ²⁺ , 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⁺ , Cd ²⁺ , Hg ²⁺ , Al ³⁺ , Ga ³⁺ , In ³⁺ , Tl ³⁺ , Si ⁴⁺ , Si ²⁺ , Ge ^{4 +} , Ge ²⁺ , Sn ⁴⁺ , Sn ²⁺ , Pb ⁴⁺ , Pb ²⁺ , As ⁵⁺ , As ³⁺ , As ⁺ , Sb ⁵⁺ , Sb ³⁺ , Sb ⁺ , Bi ⁵⁺ , Bi ^{3 +} and Bi ⁺ . The term "at least bidentate organic compound" refers to an organic

A compound which contains at least one functional group which is capable of forming at least two, preferably two coordinative bonds, and / or two or more, preferably two metal atoms in each case form a coordinate bond to a given metal ion.

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 ), -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 Cβ rings, which may optionally be condensed and independently may be suitably substituted with at least one each substituent, and / or which independently of one another may each contain at least one heteroatom, such as, for example, N, O and / or S. According to likewise preferred embodiments, functional groups in which the abovementioned radical R is absent are to be mentioned. In this regard, 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 having these functional groups is capable of forming the coordinative bond and the preparation of the framework.

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, more preferably 1 to 12, more preferably 1 to 11 and particularly preferably 1 to 10 C atoms such as 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. Particularly preferably, the aromatic compound or the aromatic part of the both aliphatic and aromatic compound one, two or three nuclei, with one or two nuclei being particularly preferred. Independently of one another, each nucleus of the compound mentioned can furthermore 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 part of the both aromatic and aliphatic compounds contains one or two Cβ 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, in the context of the present invention 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, 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, p-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,

Diimide dicarboxylic 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, l, r-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, A-

Cyclohexanedicarboxylic acid, naphthalene-1, 8-dicarboxylic acid, 2-benzoylbenzene-1,3-dicarboxylic acid, 1,3-dibenzyl-2-oxoimidazolidine-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-pyrazinedicarboxylic 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-naphthalenedicarboxylic acid, 8-nitro-2,3-naphthalenecarboxylic acid, 8-sulfo-2,3-naphthalenedicarboxylic acid, anthracene-2,3-dicarboxylic acid , 2 ', 3'-DiphenyI-p-terphenyl-4,4 "-dicarboxylic acid, diphenyl ether-4,4'-dicarboxylic acid, imidazole-4,5-dicar Bonsäure, 4 (1 H) - oxothiochromene-2,8-dicarboxylic acid, 5-tert-butyl-1, 3-benzenedicarboxylic acid, 7,8-

Quinoline dicarboxylic 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-4,11-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-methylpyrrole-3,4-dicarboxylic acid, 1-benzyl-1H-pyrrole-3,4-dicarboxylic acid, anthraquinone -l, 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-methylbenzene-1, 2,4-tricarboxylic acid acid, 1,2,3-propanetricarboxylic acid or aurintricarboxylic acid,

or tetracarboxylic acids such as

1,1-dioxide peroxy [1,2-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-benzenetetracarboxylic acid, 1,2,11,12-dodecantetracarboxylic acid, 1,2,5,6-hexanetetracarboxylic acid, 1,2,7,8- Octanetracarboxylic acid, 1, 4,5,8-naphthalenetetracarboxylic acid, 1,2,9,10-decantetracarboxylic acid, benzophenonetetracarboxylic acid, 3,3 ', 4,4'-benzophenonetetracarboxylic 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, dicerous 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 is including, inter alia, -OH, a nitro group, an amino group or an alkyl or

To name alkoxy group.

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, for example, 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 tetrabenzoate or dihydroxyterephthalic acids such as, for example, 2,5-dihydroxyterephthalic acid

(DHBDC) used.

Very particular preference is given, inter alia, to using 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.

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 more preferable if more than 25% of the total pore volume, in particular more than 50% of the total pore volume of

Pores is formed, which are in a diameter range of 100 nm to 800 nm and when more than 15% of the total pore volume, in particular more than 25% of the total pore volume of pores is formed, which are in a diameter range of up to 10 nm. The pore distribution can be determined by means of mercury porosimetry.

The sorption storage 5 is cooled according to the invention to increase the absorption capacity. This is done e.g. with the help of liquid nitrogen. In order to avoid that a temperature increase due to heat absorption takes place by the environment, the Sorp- tion memory 5 is enclosed by a thermal insulation 9.

In the embodiment shown here, the sorption storage 5 is provided with a first connection 11, with which the sorption storage 5 can be filled with the gaseous hydrocarbon. In order to prevent the gaseous hydrocarbon from flowing out of the sorption storage 5 via the first connection 11 and also to permit infestation, a refueling valve 13 is accommodated in the first connection 11. The fueling valve 13 is e.g. a check valve which opens as soon as the pressure in the connection line is greater than the pressure in the sorption storage 5. A pressure in the Sorptionsspeicher 5, which is greater than that in the connection line 11 causes the refueling valve 13 closes. This avoids that gas can flow out of the sorption storage 5 via the first port 11. A suitable valve as refueling valve 13 is e.g. a check valve.

Gas is withdrawn from the sorption storage 5 via a second connection 15. In order to be able to adjust the quantity and the pressure of the gas which is taken off via the second connection 15, a removal valve 17 is preferably arranged in the second connection 15.

In order to heat the Sorptionsspeicher 5 with the gas absorbed therein, a heating element 19 is contained in the sorption 5. As the heating element 19, e.g. e- lectric heating elements. Alternatively, however, it is also possible, e.g. Use heat exchanger as heating element 19. However, the heating element 19 is preferably an electrical heating element.

The inventive device 1 also includes a control system 21. With the control system 21, the heating rate of the heating element 19 is controlled so that when removing gas, the temperature in the Sorptionsspeicher 5 is increased such that until reaching a maximum permissible temperature does not fall below a predetermined minimum pressure in the sorption storage. For this purpose, the temperature is measured with the aid of at least one temperature sensor 23, and the pressure in the sorption storage 5 is measured with the aid of a pressure sensor 25, and the values for temperature and pressure are transmitted to the control system 21.

In the case of a stepwise increase in the temperature, gaseous hydrocarbon is withdrawn via the second port 15 until a predetermined threshold value for the pressure is reached. As soon as the threshold value for the pressure is measured with the pressure sensor 25, the heating element 19 is switched on by the control system 21 in order to increase the temperature in the sorption storage 5. For this purpose, the temperature is detected by means of the temperature sensor 23. The pressure is further detected by the pressure sensor 25. Once a predetermined upper pressure limit is reached, which is stored as a value in the control system 21, the heating process is terminated by switching off the heating element 19. It can be removed again via the second port 15 gas until the pressure has reached the predetermined threshold.

If the temperature is to be increased so that the pressure remains substantially constant, pressure and temperature are detected by means of the temperature sensor 23 and the pressure sensor 25 and processed in the control system 21 so that the heating element 19 is operated in such a way that with the pressure sensor 25 measured pressure remains substantially constant. The detection of the temperature ensures that the maximum permissible temperature is not exceeded.

The temperature detection by means of the temperature sensor 23 is particularly necessary to determine the maximum allowable temperature in the sorption 5. From the maximum permissible temperature and the minimum pressure results in the state in which the gas sampling process is terminated. The maximum temperature and the minimum pressure determine the minimum amount of gas remaining in the sorption reservoir after the removal process has ended.

FIG. 2 shows the removal process in a first embodiment in a storage capacity pressure diagram. Furthermore, FIG. 2 shows adsorption isotherms for methane on a Cu ₃ (BTC) ₂ -MOF (Basolite C300-STR3.5 from BASF AG).

The abscissa 31 shows the pressure of the methane in bar. The ordinate 33 shows the content of methane in grams per liter of tank volume. In the diagram, a first adsorption isotherm 35 at a temperature of 195 K, a second adsorption isotherm 37 at a temperature of 248 K, a third adsorption isotherm 39 at a temperature of 273 K, and a fourth adsorption isotherm 41 at a temperature of 298 K. It can be seen here that the storage capacity of the sorption storage decreases with increasing temperature and in each case can absorb a smaller amount of methane. It can also be seen that the loading of methane at low temperatures, even at low pressures, is much higher than the maximum possible loading at higher temperatures. Due to the lower possible loading at higher temperatures, methane is released from the sorption reservoir as the temperature is raised. At a temperature increase without gas removal, the pressure in the supply increases at the same time. This makes it possible to remove more gas from the Sorptionsspeicher at the same pressure and increasing temperature.

In addition to the adsorption isotherms, curves are also shown in FIG. 2 which show the content of methane in a tank without sorption storage.

The reference numeral 43 shows the remaining methane content in a tank without sorption storage at a temperature of 195 K. Here it can be seen that the methane content increases with increasing pressure. In particular, it can be seen that there is a strong increase in the range of 40 to 60 bar. This is due to a liquefaction of the methane in this pressure range. The curve designated by reference numeral 45 shows the methane content in a tank without sorption storage at a temperature of 273 K and the curve designated by reference numeral 47, the methane content in a tank without Sorptionsspeicher at a temperature of 289 K. The curves 43,45 and 47 were off a pVT database. In comparison, the curve shows the measured methane content in a tank without sorption storage at 298 K. It can be seen from these curves that with the same tank volume in a tank with sorption storage, a larger amount of methane can be stored than in a tank without sorption storage.

The maximum load of the sorption accumulator results from a permissible maximum pressure 51 in the tank and the minimum temperature that is reached. To empty the reservoir, gas is first removed from the reservoir until a minimum pressure 53 is reached. The gas removal is shown by the arrow 55. The minimum pressure 53 generally results from the pressure requirements of the gas consumer, eg an internal combustion engine or a fuel cell. For example, losses in performance must be added if the pressure falls below the minimum pressure 53. Furthermore, it is also possible that, for example, the metering valves no longer open when the pressure is lower than the minimum pressure 53. FIG. 2 shows a stepwise removal of the gas. For this purpose, gas is first removed from the sorption reservoir at a constant temperature. The gas is removed in each case along an adsorption isotherm. When the sorption storage is maximally loaded, the load decreases with decreasing pressure corresponding to the first adsorption isotherm 35, as indicated by the arrow 55. As soon as the pressure approaches the minimum pressure 53, the temperature is increased. Due to the increase in temperature, the pressure increases with constant loading. This is shown by the arrow 57. The heating is terminated upon reaching a predetermined threshold, which is between the minimum pressure 53 and the maximum permissible storage pressure. This is done for example by switching off an electrically operated heater or by stopping the heating by a heat exchanger. For example, the upper threshold may also correspond to the maximum allowable accumulator pressure.

After reaching the upper threshold, the heating is stopped or reduced and gaseous hydrocarbon can be withdrawn until the pressure returns to the lower threshold. This is repeated until either the sorption is emptied as much as possible or a predetermined temperature is reached. The predetermined maximum temperature may e.g. also be determined from the residual amount that should remain in the sorption after removal of the gaseous hydrocarbon. The removal of hydrocarbon is of course also possible during heating.

In order to avoid that the pressure drops below the predetermined minimum pressure 53 during removal, the heating is preferably started as soon as the pressure is in a range between the minimum pressure 53 and a pressure which is at most 20% greater than the predetermined minimum pressure 15 ,

In addition to the heating 57 shown here without gas removal, it is of course also possible for gaseous hydrocarbon to be removed from the sorption reservoir during the heating process.

In order to further avoid that the pressure exceeds the maximum permissible pressure 51 due to the temperature increase, it is preferably only heated until the maximum permissible storage pressure is reached. Exceeding the permissible maximum pressure 51 must be avoided in any case in order to avoid damage to the tank, where the tank may burst, if necessary. The maximum permissible pressure 51 is thus special from the strength of the tank. It is also possible that the maximum pressure results from properties of the extraction valve. Thus, it is possible, for example, that a removal valve is used which can no longer open at pressures which are above the maximum pressure 51.

FIG. 3 shows the gas removal in a second embodiment. The embodiment shown in FIG. 3 differs from the embodiment shown in FIG. 2 in that the temperature is not increased stepwise, but a continuous increase in temperature is carried out while gaseous hydrocarbon is removed from the sorption reservoir. The temperature is thereby increased so that the pressure remains substantially constant when gas is removed. This is represented by the withdrawal curve 59. Preferably, the pressure, which is kept substantially constant by the temperature increase, the minimum pressure 53. This ensures that the maximum possible amount of gas is removed from the Sorptionsspeicher with minimal energy consumption by the increase in temperature.

However, while in the embodiment shown in Figure 2, a simple 2-stage control is sufficient to perform the stepwise increase in temperature, in the embodiment shown in Figure 3, a continuous control must be made to avoid that the pressure at removal below the minimum pressure sinks.

At a storage temperature at a maximum loaded sorption of 195 K and a maximum temperature to which the gas is removed from the Sorptionsspeicher of 298 K, a maximum pressure of 50 bar and a minimum pressure of 10 bar results, for example, a maximum tank capacity, as with the Double arrow 61 is shown.

Claims

claims

1. A method for storing gaseous hydrocarbons in a Sorptionsspeicher (5), characterized in that the temperature of the stored hydrocarbon in the filled Sorptionsspeicher (5) is less than room temperature and greater than the evaporation temperature of the hydrocarbon.

2. The method according to claim 1, characterized in that the temperature of the hydrocarbon when infesting the Sorptionsspeichers (5) is less than or equal to the temperature of the stored hydrocarbon with a filled Sorptionsspeicher (5).

3. The method according to claim 1 or 2, characterized in that the Sorptionsspeicher (5) is cooled for controlling the temperature of the gaseous hydrocarbon.

4. The method according to any one of claims 1 to 3, characterized in that for emptying the Sorptionsspeichers (5) the temperature in the Sorptionsspeicher (5) is increased with decreasing content of gas until reaching a maximum allowable temperature that a predetermined minimum pressure in Sorption Store (5) is not fallen below.

5. The method according to claim 4, characterized in that a stepwise increase in the temperature is performed, each gas is removed at a constant temperature until reaching a predetermined setpoint for the pressure and upon reaching the setpoint, the temperature is increased until a predetermined upper Pressure limit is reached.

6. The method according to claim 5, characterized in that the predetermined upper pressure limit corresponds to the maximum permissible storage pressure.

7. The method according to claim 4, characterized in that from reaching a predetermined pressure, the temperature in the Sorptionsspeicher (5) is increased upon removal of gas such that the pressure remains substantially constant until a predetermined maximum allowable temperature is reached.

8. The method according to claim 7, characterized in that the predetermined pressure, from which the temperature in the sorption storage (5) is increased, is substantially equal to the predetermined minimum pressure.

9. The method according to any one of claims 1 to 8, characterized in that the gaseous hydrocarbon is selected from natural gas, methane, ethane, propane and butane.

10. An apparatus for storing gaseous hydrocarbons, comprising a Sorptionsspeicher (5), which is isolated from the environment, characterized in that the Sorptionsspeicher (5) contains zeolite, activated carbon or organometallic framework compounds.

11. The device according to claim 10, characterized in that the sorption storage (5) comprises a cooling device.

12. Device according to claim 10 or 11, characterized in that a control system (21) is included, with which the temperature increase in the sorption storage (5) at

Removal of gas can be controlled so that a predetermined minimum pressure is not exceeded until reaching a maximum allowable temperature.

13. The device according to any one of claims 10 to 12, characterized in that further comprises a heating element (19), with which the sorption (5) can be heated.

14. Device according to one of claims 10 to 13, characterized in that the sorption storage (5) comprises a first connection (11) for infestation and a second connection (15) for emptying