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    • 专利摘要:
    The present invention relates to a process for the production and storage of hydrogen by catalytic dehydrogenation based on the use of a transition metal catalyst anchored on a support of a carbon material. Additionally, the present invention also relates to the use of a transition metal catalyst anchored on a support of a carbon material for obtaining hydrogen by catalytic dehydrogenation reactions, preferably for the use of said hydrogen obtained in a cell of fuel or a combustion engine. (Machine-translation by Google Translate, not legally binding)
    公开号:ES2651161A1
    申请号:ES201730918
    申请日:2017-07-11
    公开日:2018-01-24
    发明作者:José Antonio MATA MARTÍNEZ；David VENTURA ESPINOSA；Alba CARRETERO CERDÁN；Miguel BAYA GARCÍA；Hermenegildo García Gómez
    申请人:Consejo Superior de Investigaciones Cientificas CSIC；Universidad Politecnica de Valencia；Universidad de Zaragoza；Universitat Jaume I de Castello；
    IPC主号:
    专利说明:

    The present invention relates to the use of a transition metal catalyst anchored on a support of a carbon material for obtaining hydrogen by catalytic dehydrogenation reactions, preferably for the use of said hydrogen.
    ϭϬ obtained in a fuel cell or combustion engine. Additionally, the present invention also relates to a process for the production and storage of hydrogen by catalytic dehydrogenation based on the use of said catalyst of a transition metal anchored on a support of a carbon material.
    ϭϱ
    Background of the invention
    There is a growing need to achieve a stable energy supply from alternative energy sources, which will stop the exponential increase in the
    ϮϬ pollution, especially CO2 emissions, and that in the medium term may represent a viable solution to the depletion of fossil fuels.
    Currently, some alternative forms of energy production based on the capture of natural resources are taking on a prominent role, such as Ϯϱ wind energy or solar energy (V. Blagojeviü, D. Miniü, JG Novakoviü and D. Miniü Hydrog. Energy - Challenges Perspect. 2012, 3-28). However, the main problem presented by these renewable energy sources is their intermittent nature, linked to their dependence on meteorological factors. Therefore, in recent years numerous efforts have been devoted both to the search for safe power generation systems and
    ϯϬ sustainable, such as the development of storage systems for this energy to improve its use.
    The storage of energy in the form of chemical bonds is especially promising, and in this context, the so-called “Economy of ϯϱ Hydrogen”, based on the use of hydrogen as an energy vector, stands out. Through its combination with oxygen, hydrogen allows energy to be obtained quickly and sustainably, generating only water as a byproduct. However, hydrogen is not found in the earth's crust, and therefore its production is necessary. However, it is known that such production is not sustainable, unless it is carried out through the use of wind or solar energy, in which case it would also be especially advantageous to be able to store the excess hydrogen for later use. There are different hydrogen storage processes, although many of them are not efficient or pose a high risk to users. Additionally, hydrogen storage implies a series of requirements from the point of view of infrastructure, especially at the industrial level, given the need to avoid possible
    ϭϬ overpressures during storage and its extremely flammable and reactive character.
    Technology based on the use of organic liquids as hydrogen carriers
    (i.e. Liquid Or ganic Hydrogen Car riers or LOHC) for storage and transportation is
    ϭϱ Acquiring special relevance in recent years, since it also makes it possible to store the excess energy produced by sustainable methods, thus improving its use. Therefore, this strategy based on LOHCs begins to emerge as a possible, highly versatile route to a sustainable energy system and free of carbon dioxide emissions, which also allows a cyclic hydrogenation process
    ϮϬ and dehydrogenation, which translates into the possibility of producing and storing significant amounts of hydrogen depending on the needs (P. Preuster, C. Papp Acc. Chem. Res. 2017, 50 (1), 74-85).
    This technology is based on a catalytic dehydrogenation reaction (R. H. Crabtree
    Ϯϱ Energy Environ. Sci. 2008, 1, 134-138), by means of which hydrogen can be produced quickly depending on the needs. At the same time, LOHC systems allow a safe storage of hydrogen, even facilitating its transport to the place where such energy is needed, as summarized in the following figure:
    There are different parameters that determine the efficiency of these LOHC hydrogen storage systems, one of the most widely used being the ability to
    ϱ hydrogen storage (ii.e. Hydr ogen storage capacit and or HSC), which is based on determining the mass ratio of hydrogen contained. Thus, the greater the value of this parameter, the greater the efficiency of the LOHC system because it is capable of storing a larger amount of hydrogen in a smaller volume. A second parameter of interest is the effective hydrogen storage capacity, which refers to
    ϭϬ the amount of molecular hydrogen obtained in a given process, without considering
    hydrogen atoms that do not actively participate in the generation of hydrogen.
    Cycloalkanes were the first organic compounds applied in these LOHC systems due to their high hydrogen content. However, these compounds ϭϱ required high temperatures for hydrogen generation. Subsequently, the introduction of heteroatoms in these cycloalkanes allowed to work at lower temperatures, facilitating dehydrogenation; Within these heterocyclooalkanes, the N-heterocyclic compounds as hydrogen carriers, which provide numerous advantages, especially the possibility of working at ϮϬ lower temperatures without diminishing their hydrogen storage capacity, stand out. However, the
    Dehydrogenation of this type of compounds is also endothermic, so
    they require high reaction temperatures, or the use of catalysts.Subsequently, other LOHC systems have been developed, such as the one based on
    formic acid. This system has the advantage of its easy obtaining at an industrial level and a relatively low cost, but its use leads to the formation of stoichiometric amounts of carbon dioxide.
    ϱ The LO-amino-borane system, which has a high HSC value due to its composition of light atoms, and requires relatively low reaction temperatures, is currently one of the most commonly used options for hydrogen storage. In addition, amino-borane systems have another attractive property, which consists of the difference in electronegativity between boron (2.04) and nitrogen (3.04), which
    ϭϬ favors the reaction between B-H and N-H, and therefore, the formation of molecular hydrogen. However, the amino-borane systems lead to the formation of extremely stable borates, from which it is difficult to regenerate the starting products, and therefore, to achieve a reversible system that allows hydrogen storage-generating according to demand. .
    ϭϱ The alcohololysis or dehydrogenation reaction of hydrosilanes in silanoalcohol LOHC systems (D. Wechsler, Y. Cui, D. Dean, B. Davis, PG Jessop J. Am. Chem. Soc. 2008, 130, 17195-17203) is a catalytic process thermodynamically favored by the formation of Si-O bonds in the resulting silyl ether compound, and entropically favored by the
    ϮϬ gas release. Therefore, the use of this silane-alcohol system as LOHC allows working with low temperatures to obtain hydrogen, and also has great versatility due to the different silanes and alcohols currently available. In addition, the silyl ether obtained as a result of this reaction can be transformed allowing recovery of the initial silane or, alternatively, can be used in the
    Ϯϱ silicone industry.
    This last way of obtaining hydrogen, however, although it is especially promising, still has certain limitations in terms of the possibility of regenerating the starting products, especially the catalyst, which is often deactivated, or
    ϯϬ is lost in the reaction medium itself, leading to a phenomenon known as “leaching,” which ends the loss of part of the catalyst.
    Therefore, there is a need in the sector to find new solutions that allow carrying out the catalytic alcohololysis or dehydrogenation process to obtain ϯϱ hydrogen in a highly efficient manner, with good catalyst stabilization, and
    preferably, with a good resilience of this, which will allow recycling.
    ϱ DETAILED DESCRIPTION OF THE INVENTION An object of the present invention is to provide a process for the production and storage of hydrogen by catalytic dehydrogenation based on the use of a transition metal catalyst anchored on a support of a carbon material.
    ϭϬ ϭϱ The production and storage of hydrogen is favored by the use of a heterogeneous catalyst formed by a transition metal anchored on a carbon support. The main advantage of this type of catalysts is that it allows to stabilize the catalytically active species, and at the same time, facilitate the recovery of the catalyst, which allows recycling and reuse in subsequent dehydrogenation reactions.
    ϮϬ In the present invention, "carbon aggregate" means any carbon cluster of the fullerenes family (e.g. molecule C60, molecule C70), or fullerene type particles such as aggregates of ultrafine carbon particles. By "carbon fibers" is meant the set of filaments of approximately 5-10 micrometers in diameter, mainly composed of carbon atoms bonded together.
    Ϯϱ By "carbon nanotubes" is meant in the present invention a grouping of carbon atoms linked together in a hexagonal manner, where each atom covalently bonds to three other carbon atoms, forming a sheet that bends over itself giving place to tubes of nanometric size.
    ϯϬ In the present invention, "graphene" is understood as a single sheet of carbon atoms packed together in a hexagonal pattern.
    ϯϱ By "graphene derivatives" is meant any graphene structure that has been functionalized by the addition of atoms other than carbon, such as hydrogen, oxygen or halogen, which can be attached to said carbon atoms by different types of bonds or interactions , modifying its local structure and / or properties
    Electronic Examples of graphene derivatives include, but are not limited to, hydrogenated graphene (ie graphene), fully fluorinated graphene (ie fluorografen or C1F1), oxidized graphene (ie GO) or graphene oxide, and reduced graphene oxide (ie rGO) .
    ϱ The term "approximately", as used in the present invention when it precedes a temperature value and refers to it, is intended to designate any temperature value in a range corresponding to ± 10% of its numerical value, preferably a range corresponding to ± 5% of its numerical value, more preferably a range corresponding to ± 2% of its numerical value, and even more preferably a
    ϭϬ range corresponding to ± 1% of its numerical value. For example, "about 100 ° C" should be interpreted as a range of 90 ° C to 110 ° C, preferably a range of 95 ° C to 105 ° C, more preferably a range of 98 ° C to 102 ° C, and even more preferably a range of 99 ° C to 101 ° C.
    ϭϱ In a first aspect of the invention, there is provided a process for the production and storage of hydrogen by catalytic dehydrogenation which comprises contacting an amount of a transition metal catalyst anchored on a support of a carbon material selected from the group consisting of carbon aggregates, carbon fibers, carbon nanotubes, graphene and graphene derivatives, with
    ϮϬ an amount of at least one alcohol and an amount of at least one silane, wherein said at least one silane is converted to hydrogen and at least one silyl ether.
    It will be apparent to the person skilled in the art that the contacting of the different elements involved in the catalytic dehydrogenation reaction, that is, said
    Ϯϱ catalyst of a transition metal anchored on a carbon material, said at least one silane, and said at least one alcohol, can be produced simultaneously or sequentially, where the sequence and the rate of addition can be determined, by for example, for the different properties of silanes and alcohols that can be used as a LOHC system.
    ϯϬ In a preferred embodiment, said process for the production and storage of hydrogen by catalytic dehydrogenation comprises:
    a) disposing an amount of a transition metal catalyst anchored on a ϯϱ support of a carbon material selected from the group consisting of
    carbon aggregates, carbon fibers, carbon nanotubes, graphene and graphene derivatives, with an amount of at least one alcohol, and b) adding an amount of at least one silane over the mixture of step a),
    ϱ wherein as a result of said step b) said at least one silane is converted to hydrogen and at least one silyl ether.
    This procedure is applicable to a wide variety of silanes and alcohols, which form different LOHC systems with a wide range of ϭϬ hydrogen storage capacities. In fact, the versatility of the silanes can serve to significantly increase the hydrogen storage capacity, and so, while the use of a primary silane results in the release of three moles of hydrogen for each mole of this silane, it can be increased the generation of hydrogen through the use of, for example, disilanes, which can generate three moles of hydrogen per mole of silane.
    ϭϱ In a preferred embodiment, the process of the present invention is carried out at a temperature between about -25 ° C and about 40 ° C. More preferably, the process of the present invention is carried out at a temperature between about -15 ° C and about 30 ° C, and
    ϮϬ even more preferably, the process of the present invention is carried out at a temperature of about 30 ° C.
    With respect to said catalyst of a transition metal anchored on a support of a carbon material, in a preferred embodiment of the present process of the invention Ϯϱ it is present in a molar relationship with respect to said at least one silane equal to or less than 1, 5 mmol: 100 mmol, respectively, wherein the moles of catalyst do not include the support of a carbon material. Even more preferably, said transition metal catalyst anchored on a support of a carbon material is present in a molar ratio with respect to said at least one silane equal to or less than 0.5 mmol: 100 ϯϬ mmol, respectively, wherein the catalyst moles do not include the support of a carbon material. Even more preferably, said transition metal catalyst anchored on a support of a carbon material is present in a molar ratio relative to said at least one silane equal to or less than 0.1 mmol: 100 mmol, respectively, in where the catalyst moles do not include the support of a ϯϱ carbon material. Even more preferably, said transition metal catalyst anchored on a support of a carbon material is present in a molar relationship with respect to
    said at least one silane equal to or less than 0.05 mmol: 100 mmol, respectively, wherein the moles of catalyst do not include the support of a carbon material.
    The activity of said catalyst of a transition metal anchored on a support of a
    ϱ Carbon material is important for optimal management of hydrogen production through the procedure described above. The TOF or “turnover frequency” parameter, widely known in the catalysis sector, quantifies the specific activity of a catalytic center for a reaction determined by the number of molecular reactions or catalytic cycles that occur in said catalytic center by
    ϭϬ unit of time. Thus, the catalysts used in the process of the present invention have a TOF value for the catalytic dehydrogenation reaction of silanes between 1.90 s-1 and 18.00 s-1, which shows that they are catalysts which exhibit excellent activity for this catalytic dehydrogenation reaction, which results in a shelf life of said catalysts of
    ϭϱ several months, which undoubtedly represents a great economic advantage for its industrial application.
    In addition, various comparative catalytic tests performed with some of the heterogeneous catalysts (i.e. catalysts of a transition metal anchored on a
    ϮϬ support of a carbon material) used in the process of the present invention, and its homogeneous analogs (ie molecular complexes of the same transition metal, with similar coordination ligands, without anchoring in a solid support), revealed the superiority of the catalysts of the first type in terms of catalytic activity.
    Ϯϱ It is postulated, without limitation, that the use of a catalyst supported on a carbon material contributes to further stabilization of the catalytically active species formed during the process of the present invention, thereby improving the activity of the catalyst.
    ϯϬ Preferably, the catalyst of a transition metal anchored on a support of a carbon material used in the present process comprises a compound of general formula (I):
    A-X-B- [MLn] (I)
    ϯϱ
    where:
    ϵ

    - A is a polycyclic aromatic hydrocarbon, -X is a spacer fragment that is selected from the group consisting of [-CH2-] m, [-CH2-O-] m, [-aryl-CH2-] m and [-CH2- NH-] m, where m has a value ϱ between 1 and 4, -B is an N-heterocyclic group with a ring size between 5 and 8 members, consisting of carbon atoms and at least one atom of nitrogen,
    - [MLn] is a coordination compound, where M is a transition metal, L is a coordination ligand, and n has a value between 1 and 6, and
    ϭϬ wherein said support of a carbon material and said compound of general formula (I) are joined by non-covalent bonds.
    With respect to group A of the compound of general formula (I), "hydrocarbon"
    ϭϱ polycyclic aromatic ”means any aromatic organic compound that contains two or more benzene rings fused in a linear, angular or cluster manner. Preferably, said group A is selected from the group consisting of anthracene, benzopyrene, chromene, coronen, naphthacene, pentacene, naphthalene, phenanthrene, pyrene and triphenylene. More preferably, said group A is benzopyrene.
    ϮϬ Said group A advantageously allows the immobilization of the coordination compound [MLn], to which it is linked through the spacer fragment X and the N-heterocyclic fragment, on the support made of a carbon material, through ʌ-ʌ interactions , also known in the sector as ʌ-ʌ stacking or “ʌ-ʌ stacking”. These
    Ϯϱ interactions are non-covalent in nature and occur between the aromatic fragments of said group A and the support, through their ʌ type bonds.
    The function of the spacer fragment X is to act as a covalent bond bridge between the polycyclic aromatic hydrocarbon A and the N-heterocyclic fragment B. Accordingly,
    puente said bridge can be any organic group that provides stability to the union between A and B, such as an alkyl group [-CH2-] m, an ether group [-CH2-O-] m, an arylalkyl group [-aryl- CH2-] m or an amine [-CH2-NH-] m.
    In a preferred embodiment, the spacer fragment X is [-CH2-] m, where m has a
    ϯϱ value between 1 and 4. Even more preferably, the spacer fragment X is [-CH2-], that is, X is [-CH2-] m where m has a value equal to 1.
    With respect to group B of the compound of general formula (I), in the present invention "N-heterocyclic group" means a heterocycle with a ring size between 3 and 15 members, consisting of carbon atoms and at least one nitrogen atom; more preferably, said heterocyclic group has a ring size ϱ between 5 and 8 members, consisting of carbon atoms and at least one nitrogen atom. Depending on the number of rings, said heterocyclic group may be, for example, monocyclic, bicyclic or tricyclic, and may additionally include condensed ring systems. In addition, both the carbon atoms and said at least one nitrogen atom may be optionally substituted by a C1-C10 alkyl group, or by an ϭϬ aryl group. Examples of such N-heterocyclic groups include, but are not limited to, azepines, benzimidazole, benzothiazole, isothiazole, imidazole, indole, purine, pyridine, pyrimidine, quinoline, isoquinoline, thiadiazole, pyrrole, pyrazole, pyrazoline, oxazole, isoxazole, triazole and imidazole.
    In a preferred embodiment, said group B is an N-heterocyclic group selected from
    ϭϱ pyridine, pyrimidine, pyrazoline, quinoline, isoquinoline, pyrrole, indole, purine, imidazole, pyrazole and thiazole. More preferably, said group B is an imidazole group optionally substituted by a C1-C10 alkyl group or by an aryl group. Even more preferably, said group B is N-methylimidazole.
    ϮϬ "Alkyl group" means, in the context of the present invention, any linear or branched monovalent saturated hydrocarbon with a number of carbon atoms between 1 and 10, which may optionally be cyclic or include cyclic groups, which may optionally include in its skeleton one or more heteroatoms selected from nitrogen, oxygen or sulfur, and which may be optionally substituted
    Ϯϱ by one or more substituents selected from halogen, hydroxyl, alkoxy, carboxyl, carbonyl, cyano, acyl, alkoxycarbonyl, amino, nitro, mercapto and alkylthio. Examples of alkyl groups include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, cyclopentyl, cyclohexyl or cycloheptyl.
    ϯϬ In the present invention, "aryl group" is understood as an aromatic hydrocarbon which preferably contains a number of carbon atoms comprised between 3 and 12 carbon atoms, more preferably between 6 and 12 carbon atoms, such as for example cyclopropenyl, phenyl, tropyl, indenyl, naphthyl, azulenyl, biphenyl, fluorenyl or anthracenyl. This aryl group may be optionally substituted by one or more
    ϯϱ substituents that are selected from alkyl, haloalkyl, aminoalkyl, dialkylamino, hydroxy, alkoxide, phenyl, mercapto, halogen, nitro, cyano and alkoxycarbonyl. Optionally, said aryl group may include in its skeleton one or more heteroatoms selected from nitrogen, oxygen or sulfur.
    In the present invention, the [MLn] group is a coordination compound, wherein M is
    ϱ a transition metal and L are coordination ligands, linked together by coordination links, weaker than covalent bonds. The coordination compound may have one or more metal centers, i.e. transition metals.
    "Transition metal" means any element of block d (i.e. groups III-XII) of
    ϭϬ the periodic table of chemical elements. Preferably, the transition metal M is selected from the group consisting of ruthenium (Ru), osmium (Os), rhodium (Rh), iridium (Ir), palladium (Pd), platinum (Pt), silver (Ag) and gold (Au). More preferably, the transition metal M is ruthenium.
    ϭϱ Said L ligands can be neutral, cationic or anionic, and can have an donor or ʌ acceptor character depending on the metal to which they are coordinated and the oxidation state of this, in addition to their own electronic nature. Additionally, said ligands may have different hapticities (i.e. number of atoms of a ligand bound to a metal center), and may behave, for example, as ligands
    ϮϬ monohapto (e.g. ƾ1-allyl), dihapto (e.g. ƾ2-butadiene), trihapto (e.g. ƾ3-allyl) or tetrahapto (e.g. ƾ4-butadiene).
    The value n corresponding to the number of ligands bound to the central transition metal depends on both their hapticity and the oxidation state of the metal.
    Ϯϱ Preferably, n has a value between 1 and 4. In particular, when n is greater than 1, said n coordination ligands L may be the same or different.
    Examples of [MLn] groups include, but are not limited to, [RuCl2 (p-cimeno)] 2, [RhCl (COD)] 2, [IrCl (COD)] 2, [PdCl (ƾ3-allyl)] 2 or [AuCl (SMe2)]. The abbreviation "COD" corresponds to the ligand
    ϯϬ 1,5-cyclooctadiene.
    In a preferred embodiment, the support of a carbon material on which the catalyst of a transition metal is anchored is a graphene derivative that is selected from reduced graphene oxide (rGO) or oxidized graphene oxide. More preferably, said
    ϯϱ support of a carbon material is reduced graphene oxide (rGO).
    In particular, the catalyst of a transition metal anchored on a support of a carbon material used in the present process comprises a compound of general formula (I):
    ϱ A-X-B- [MLn] (I)
    where:
    - A is benzopyrene, ϭϬ -X is [-CH2-] m where m is equal to 1,
    - Bes N-methylimidazole, and
    - [MLn] is a coordination compound, wherein M is ruthenium, n is equal to 3, and said 3 coordination ligands L are selected from the group consisting of Cl, Br, I, p-cimeno, pyridine, cyclopentadienyl, 1,5-cyclooctadiene, ƾ3-allyl,
    ϭϱ dimethyl sulphide and dimethylsulfoxide and any combination thereof,
    wherein said support of a carbon material is reduced graphene oxide and said compound of general formula (I) are joined by non-covalent bonds.
    With respect to said at least one alcohol used in step a) of the process of the invention for the production and storage of hydrogen by catalytic dehydrogenation, this is preferably an alcohol with a number of carbon atoms between 1 and 10; preferably, said at least one alcohol has a number of carbon atoms between 1 and 8. More preferably, said alcohol is
    Ϯϱ selects between methanol, ethanol, propanol, isopropanol and benzyl alcohol, and even more preferably, said alcohol is methanol.
    The term "silane", in the context of the present invention, refers to any linear or branched organosilane, polysilane or silane, which may have one or more
    ϯϬ substituents. Likewise, the term "silyl" refers to a radical corresponding to a silane, and therefore, is considered to be included within the group of silanes.
    Preferably, said at least one silane is a compound of the formula SiR1R2R3H, wherein R1, R2 and R3 are the same or different and are selected from the group consisting of ϯϱ hydrogen, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, aryl optionally substituted, optionally heteroaryl
    substituted, optionally substituted cycloalkyl, optionally substituted heterocycloalkyl, optionally substituted silyl and optionally substituted polysilyl. Said one or more substituents are independently selected from the group consisting of alkyl, alkenyl, alkynyl, aryl, heteroaryl, cycloalkyl, heterocycloalkyl, acyl, carboxyl, halide,
    ϱ hydroxyl, ether, nitro, cyano, amido, amino, acylamido, acyloxide, thiol, thioether, sulfoxide, sulfonyl, thioamido, sulfonamido and silyl.
    More preferably, said at least one silane is a compound of formula SiR1R2R3H, wherein R1 and R2 are the same or different alkyl groups, optionally substituted, and R3 is a
    ϭϬ aryl group, optionally substituted, wherein said one or more substituents are selected independently from the group consisting of alkyl, alkenyl, alkynyl, aryl, heteroaryl, cycloalkyl, heterocycloalkyl, acyl, carboxyl, halide, hydroxyl, ether, nitro, cyano , amido, amino, acylamido, acyloxide, thiol, thioether, sulfoxide, sulphonyl, thioamido, sulfonamido and silyl.
    ϭϱ The process for the production and storage of hydrogen by catalytic dehydrogenation may contain a further additional step, intended to recover the catalyst, and regenerate the initial hydrosilane from the silyl ether obtained as a result of the process of the invention by a reduction reaction. with a
    ϮϬ reducing agent. This regeneration of the initial hydrosilane also involves the storage of a new amount of hydrogen in the form of new chemical bonds, which can be subsequently released when necessary, by means of the present catalytic dehydrogenation process.
    Ϯϱ Preferably, said process of the present invention comprises a further additional step (i.e. after the completion of the catalytic dehydrogenation reaction), comprising the following sub-stages:
    i) separating the catalyst from a transition metal anchored on a support of a ϯϬ carbon material from the crude resulting from stage b), and ii) subjecting the liquid fraction of the crude separated in stage i) to a reduction reaction with At least one reducing agent.
    The separation of the catalyst from the sub-stage i) can be carried out by filtration,
    ϯϱ decantation, or any other method of separation known in this sector of the technique suitable for this purpose. It has been found that, surprisingly, the catalysts of a transition metal anchored on a support of a carbon material recovered through step (i) can be subsequently recycled and reused in at least 9 additional catalytic dehydrogenation reactions, without suffering No loss of catalytic activity. It is considered that this beneficial effect is influenced by the fact that, being
    ϱ Supported heterogeneous catalysts, their deactivation processes are minimized, an aspect also favored by the fact that said catalytic hydrogenation reactions are carried out at low temperatures.
    In addition, it has been confirmed that the mild experimental conditions of the
    ϭϬ Catalytic dehydrogenation does not affect the properties of the carbon material support to which the catalyst of a transition metal is anchored. By way of illustration, high resolution transmission electron microscopy (HRTEM) images of a reduced graphene oxide (rGO) support used in the anchoring of one of the ruthenium catalysts used in the present process are shown in Fig. .
    ϭϱ Specifically, Fig. 1a shows the morphology of said reduced graphene oxide before the use of the anchored catalyst in a catalytic dehydrogenation process, while Fig. 1b shows the morphology of the same reduced graphene oxide, after use in 10 catalytic cycles These microscopy images confirm that there is no change in the morphology of said reduced graphene oxide.
    ϮϬ On the other hand, said at least one sub-stage reducing agent ii) is preferably selected from the group consisting of LiAlH4, LiH, NaBH4, DIBAL-H and any of their mixtures. More preferably, said reducing agent is LiAlH4.
    Segundo A second aspect of the invention relates to the use of a transition metal catalyst anchored on a support of a carbon material to obtain hydrogen by catalytic dehydrogenation reactions.
    Preferably, in said use, said transition metal catalyst anchored on a ϯϬ support of a carbon material comprises a compound of general formula (I):
    A-X-B- [MLn] (I)where:-A is a polycyclic aromatic hydrocarbon,
    - X is a spacer fragment that is selected from the group consisting of [-CH2-] m, [-CH2-O-] m, [-aryl-CH2-] m and [-CH2-NH-] m, where m It has a value between 1 and 4,
    - B is an N-heterocyclic group with a ring size between 5 and 8 ϱ members, consisting of carbon atoms and at least one nitrogen atom,
    - [MLn] is a coordination compound, where M is a transition metal, L is a coordination ligand, and n has a value between 1 and 6, and
    wherein said support of a carbon material and said compound of general formula (I) ϭϬ are linked by non-covalent bonds.
    Even more preferably, the hydrogen obtained through the use of the invention described herein can be used in a fuel cell or a combustion engine. It will be apparent to the person skilled in the art that there are numerous alternatives for
    ϭϱ supplying the hydrogen produced by the catalytic dehydrogenation reaction of the present invention to said fuel cell or said combustion engine, such as for example the connection by conduits and / or tubes, which may preferably contain valves to regulate the flow of hydrogen which Enter that cell or engine.
    ϮϬ Throughout the description and the claims, the word "comprises" and the variations of the word are not intended to exclude other technical characteristics, additives, components or steps. The objects, advantages and additional features of the invention will be apparent to those skilled in the art after analysis of the description, or can be learned from the examples of the invention. The following examples and drawings
    Ϯϱ are provided illustratively and are not intended to be limiting of the present invention. Additionally, the invention covers all possible combinations of the particular and preferred embodiments of the present document.
    Brief description of the drawings
    ϯϬ
    Fig. 1 - High resolution transmission electron microscopy (HRTEM) images of a reduced graphene oxide (rGO) support used for anchoring one of the ruthenium catalysts of the present invention. Fig. 1a shows the morphology of said reduced graphene oxide before the use of the anchored catalyst ϯϱ in a catalytic dehydrogenation process, while Fig. 1b shows the morphology of the same reduced graphene oxide, after use in 10 catalytic cycles. .
    Examples
    Evaluation of catalytic dehydrogenation of silanes and alcohols using a supported ruthenium catalyst on reduced graphene oxide (Ru-rGO system)
    ϱ
    Reaction conditions:
    - 1.0 mmol of silane (PhMe2SiH, PhSiH3 or Ph2SiH2) -0.05 mol% of ruthenium catalyst supported on reduced graphene oxide (rGO) ϭϬ with the following structure:
    wherein the catalyst moles considered do not include the reduced graphene oxide support. -1 ml of alcohol ROH (MeOH, EtOH or n-BuOH) ϭϱ -T = 30 ° C -t = 10 minutes
    The procedure consists in adding the corresponding amount of silane on a solution of the ruthenium catalyst in the alcohol ROH corresponding to 30 ° C, and maintaining the reaction for 10 minutes.
    Table 1 shows the results obtained with the silanes and alcohols described above, where a practically quantitative conversion of the silane to the corresponding silyl ether was observed in all cases:
    Ϯϱ
    Table 1
    Ru-rGO (Molar%) SilaneAlcoholYield (%) [a]
    0.05 PPhMe2SiH MeOH100
    0.05 PPhMe2SiH EtOH100 (93)
    0.05 PPhMe2SiHnBuOH95 (90)
    0.05 PhSiH3 MeOH90
    0.05 Ph2SiH2nBuOH100 (94)
    ϱ
    [a] The yield of the product indicated in parentheses was determined by proton nuclear magnetic resonance (NMR-1H), using 1,33,5-trimethoxybenzene as the external standard.
    PhMe2SiH silane recovery procedure by hydrogenation / reduction
    ϭϬ
    An example of hydrogenation reaction // reduction for
    regeneration of the silane used as the starting product (i.e. LOHC silane-alcohol) in the process of the present invention. Said reaction is based on the redduction of the silyl ether formed during the catalytic dehydrogenation.
    ϭϱ
    Me
    Et2OPh Si OMe + LiAlH4
    Ph SiH + MMeOH
    4 pm Me Me
    25ºC
    LiAlH4 (79.9 mg, 2 mmol) is added over a solution of PhMe2SiOMMe (200 µl, 1 mmol) in diethyl ether, and the suspension is stirred for 16 hours at room temperature. TO
    ϮϬ Then, excess LiAlH4 is neutralized by the addition of 1M HCCl (10 ml), and extraction is carried out with dichloromethane. Subsequently, the set of organic phases is brought to dryness, thus isolating the PhMe2SiH silane (90% yield).
    权利要求:
    Claims (24)
    [1]
    one. Process for the production and storage of hydrogen by catalytic dehydrogenation characterized in that it comprises contacting an amount of a transition metal catalyst anchored on a support of a carbon material selected from the group consisting of carbon aggregates, carbon fibers , carbon nanotubes, graphene and graphene derivatives, with an amount of at least one alcohol and an amount of at least one silane, wherein said at least one silane is converted to hydrogen and at least one silyl ether.
    [2]
    2. Method according to claim 1, comprising:
    a) disposing an amount of a transition metal catalyst anchored on a support of a carbon material selected from the group consisting of carbon aggregates, carbon fibers, carbon nanotubes, graphene and graphene derivatives, with an amount of at least one alcohol, and
    b) add an amount of at least one silane over the mixture of step a),
    wherein as a result of said step b) said at least one silane is converted to hydrogen and at least one silyl ether.
    [3]
    3. Process according to claim 1 or 2, which is carried out at a temperature between about -25 ° C and about 40 ° C.
    [4]
    Four. Process according to any of claims 1-3, wherein said transition metal catalyst anchored on a support of a carbon material is present in a molar ratio with respect to said at least one equal silane.
    or less than 1.5 mmol: 100 mmol, respectively, wherein the moles of catalyst do not include the support of a carbon material.
    [5]
    5. Process according to any one of claims 1-4, wherein said transition metal catalyst anchored on a support of a carbon material has a TOF value for the catalytic dehydrogenation reaction of silanes between 1.90 s- 1 and 18.00 s-1.
    [6]
    6. Process according to any one of claims 1-5, wherein said transition metal catalyst anchored on a support of a carbon material comprises a compound of general formula (I):
    A-X-B- [MLn] (I)
    wherein: -A is a polycyclic aromatic hydrocarbon, -X is a spacer fragment that is selected from the group consisting of
    [-CH2-] m, [-CH2-O-] m, [-aryl-CH2-] m and [-CH2-NH-] m, where m has a value between 1 and 4,
    - B is an N-heterocyclic group with a ring size between 5 and 8 members, consisting of carbon atoms and at least one nitrogen atom, - [MLn] is a coordination compound, where M is a metal of transition, L is
    a coordination ligand, and n has a value between 1 and 6, and
    wherein said support of a carbon material and said compound of general formula (I) are joined by non-covalent bonds.
    [7]
    7. A method according to claim 6, wherein said group A is selected from the group consisting of anthracene, benzopyrene, chromene, coronenne, naphthacene, pentacene, naphthalene, phenanthrene, pyrene and triphenylene.
    [8]
    8. Method according to claim 6 or 7, wherein X is [-CH2-] m, wherein m has a value between 1 and 4.
    [9]
    9. Process according to any of claims 6-8, wherein group B is an N-heterocyclic group selected from pyridine, pyrimidine, pyrazoline, quinoline, isoquinoline, pyrrole, indole, purine, imidazole, pyrazole and thiazole.
    [10]
    10. Process according to any of claims 6-9, wherein group B is an imidazole group optionally substituted by a C1-C10 alkyl group, or by an aryl group.
    [11]
    eleven. Method according to any of claims 6-10, wherein M is a transition metal selected from the group consisting of ruthenium, osmium, rhodium, iridium, palladium, platinum, silver and gold.
    [12]
    12. Method according to any of claims 6-11, wherein M is ruthenium.
    [13]
    13. Method according to any of claims 6-12, wherein when n is greater than 1, said n coordination ligands L are the same or different.
    [14]
    14. Method according to claim 13, wherein:
    -A is benzopyrene,-X is [-CH2-] m, where m is equal to 1,-Bes N-methylimidazole, and- [MLn] is a coordination compound where M is ruthenium, n is equal to 3, and
    said 3 coordination ligands L are selected from the group consisting of Cl, Br, I, p-cimeno, pyridine, cyclopentadienyl, 1,5-cyclooctadiene, ŋ3-allyl, dimethylsulfide, dimethylsulfoxide and any combination thereof,
    wherein said support of a carbon material is reduced graphene oxide and said compound of general formula (I) are joined by non-covalent bonds.
    [15]
    fifteen. Method according to any of claims 1-14, wherein said support of a carbon material is a graphene derivative selected from reduced graphene oxide or oxidized graphene oxide.
    [16]
    16. Process according to any of claims 1-15, wherein said support of a carbon material is reduced graphene oxide.
    [17]
    17. Process according to any one of claims 1-16, wherein said at least one silane is a compound of formula SiR1R2R3H, wherein R1, R2 and R3 are the same or different and are selected from the group consisting of hydrogen, optionally alkyl substituted, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted cycloalkyl, optionally substituted heterocycloalkyl, silyl
    optionally substituted and optionally substituted polysilyl, wherein said one or more substituents are selected independently from the group consisting of alkyl, alkenyl, alkynyl, aryl, heteroaryl, cycloalkyl, heterocycloalkyl, acyl, carboxyl, halide, hydroxyl, ether, nitro, cyano , amido, amino, acylamido, acyloxide, thiol, thioether, sulfoxide, sulphonyl, thioamido, sulfonamido and silyl.
    [18]
    18. Process according to claim 17, wherein said at least one silane is a compound of formula SiR1R2R3H, wherein R1 and R2 are the same or different alkyl groups, optionally substituted, and R3 is an aryl group, optionally substituted, wherein said one or more substituents are selected independently from the group consisting of alkyl, alkenyl, alkynyl, aryl, heteroaryl, cycloalkyl, heterocycloalkyl, acyl, carboxyl, halide, hydroxyl, ether, nitro, cyano, amido, amino, acylamido, acyloxide, thiol , thioether, sulfoxide, sulfonyl, thioamido, sulfonamido and silyl.
    [19]
    19. Process according to any one of claims 1-18, wherein said at least one alcohol is methanol.
    [20]
    twenty. Method according to any of claims 1-19, comprising a further additional step, comprising:
    i) separating the catalyst from a transition metal anchored on a support of a carbon material from the crude resulting from step b), and
    ii) subjecting the liquid fraction of the crude separated in step i) to a reduction reaction with at least one reducing agent.
    [21]
    twenty-one. Process according to claim 20, wherein said at least one reducing agent is selected from the group consisting of LiAlH4, LiH, NaBH4, DIBAL-H and any of their mixtures.
    [22]
    22 Use of a transition metal catalyst anchored on a support of a carbon material to obtain hydrogen by catalytic dehydrogenation reactions.
    [23]
    2. 3. Use according to claim 22, wherein said transition metal catalyst anchored on a support of a carbon material comprises a compound of general formula (I):
    A-X-B- [MLn] (I)
    where:5 -A is a polycyclic aromatic hydrocarbon,
    - X is a spacer fragment that is selected from the group consisting of [-CH2-] m, [-CH2-O-] m, [-aryl-CH2-] m and [-CH2-NH-] m, where m It has a value between 1 and 4,
    - B is an N-heterocyclic group with a ring size between 5 and 8 members, consisting of carbon atoms and at least one nitrogen atom, - [MLn] is a coordination compound, where M is a metal transition, L is a coordination ligand, and n has a value between 1 and 6, and
    wherein said support of a carbon material and said compound of general formula (I) are joined by non-covalent bonds.
    [24]
    24. Use according to claim 22 or 23, wherein said hydrogen obtained is used in a fuel cell or combustion engine.
    Fig. 1
    (1st)
    (1 B)
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    同族专利:
    公开号 | 公开日
    WO2019012171A1|2019-01-17|
    ES2651161B2|2018-08-13|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    US20080267859A1|2005-08-23|2008-10-30|Abu-Omar Mahdi M|Catalytic hydrogen production from hydrolytic oxidation of organosilanes|
    WO2015071521A1|2013-11-18|2015-05-21|Universitat Jaume I De Castelló|Carrier for catalysts made of graphene derivatives|
    WO2011098614A1|2010-02-15|2011-08-18|Universite De La Mediterranee Aix-Marseille Ii|Phosphine-oxide catalyzed process of production of hydrogen from silylated derivatives as hydrogen carrier|
    KR101310777B1|2011-04-21|2013-09-25|고려대학교 산학협력단|Silane-based hydrogen storage materials and method for hydrogen release and regeneration|
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