Phosphorus-doped PGM type catalyst and catalyst system for storing and releasing hydrogen in organic hydrogen carriers

Abstract

This invention relates to catalysts and their production that can be used for hydrogenating and dehydrogenating organic hydrogen carrier compounds. The catalyst consists of a specially phosphorus-doped PGM-type catalyst. This can be used, for example, for use in fuel cells of electric propulsion vehicles, to store and release hydrogen on demand. Similarly, apparatus and use thereof comprising the catalyst of the present invention are intended.

Description

[Technical Field]

[0001] This invention relates to catalysts and their production that can be used for hydrogenating and dehydrogenating organic hydrogen carrier compounds. The catalyst consists of a specially phosphorus-doped PGM-type catalyst. This can be used, for example, for use in fuel cells of electric propulsion vehicles, to store and release hydrogen on demand. Similarly, apparatus and use thereof comprising the catalyst of the present invention are intended.

[0002] Within the framework of the European Union's "Green Deal" campaign, decarbonizing mobility is a key pillar. Several aspects related to this have already been addressed and discussed intensively in the field of technology (https: / / europa.eu / newsroom / content / presentation-efficient-and-green-mobility-package_en). When discussing carbon-free propulsion of vehicles, hydrogen fuel is often mentioned as a promising energy carrier, especially when hydrogen is produced from sustainable sources such as wind or solar energy generation.

[0003] Hydrogen is found in Group 1 and Period 1 of the periodic table, meaning it is the lightest element. Hydrogen is rarely found in its pure form in the atmosphere. In a flame of pure hydrogen burning in air, hydrogen (H2) reacts with oxygen (O2) to form water (H2O), releasing energy in the process.

[0004] [ka]

[0005] In atmospheric air rather than pure oxygen, hydrogen combustion can produce small amounts of nitrogen oxides along with water vapor.

[0006] On a weight basis, the heat of combustion of hydrogen gas is about three times that of hydrocarbon-based fuels, making it an efficient and attractive energy carrier. However, as a result of hydrogen gas's very low density, its energy density on a volume basis is lower compared to hydrocarbon fuels.

[0007] Hydrogen fuel is a zero-carbon fuel when burned with oxygen. Hydrogen fuel can be used in fuel cells or internal combustion engines (e.g., HICEVs). Regarding hydrogen-powered vehicles, hydrogen was initially used in commercial fuel cell vehicles such as passenger cars and has been used in fuel cell buses for many years.

[0008] Fuel cells, particularly proton-exchange membrane fuel cells (PEMFCs), also known as polymer electrolyte membrane (PEM) fuel cells, are primarily developed for transportation applications. Their notable features include a lower temperature / pressure range (50°C to 100°C) and a special proton-conducting polymer electrolyte membrane (https: / / en.wikipedia.org / w / index.php?title=Proton-exchange_membrane_fuel_cell&oldid=1064212583). In contrast to the direct combustion of hydrogen and oxygen gases to generate thermal energy, proton-exchange membrane fuel cells convert chemical energy released during an electrochemical reaction between hydrogen and oxygen into electrical energy. The hydrogen stream is delivered to the anode side of the membrane electrode assembly (MEA), where it is catalytically decomposed into protons and electrons. This oxidative half-cell reaction, or hydrogen oxidation reaction (HOR), is represented by the following equation:

[0009] [ka]

[0010] The newly formed protons permeate through the polymer electrolyte membrane (PEM) to the cathode side. Electrons move along the external load circuit to the cathode side of the MEA, thus generating the current output of the fuel cell. Meanwhile, an oxygen stream is delivered to the cathode side of the MEA. On the cathode side, oxygen molecules react with the protons permeating the polymer electrolyte membrane and the electrons arriving through the external circuit to form water molecules. This reducing half-cell reaction, or oxygen reduction reaction (ORR), is represented by the following equation:

[0011] [ka]

[0012] For example, in mobile applications, storing hydrogen for intended use to supply hydrogen to fuel cells is one of the major technical challenges. Methods for storing hydrogen include mechanical approaches such as high pressure and low temperature, or chemical compounds that release H2 on demand. Interest in using hydrogen for on-board energy storage in zero-emission vehicles is motivating the development of new storage methods better suited to this new application. The most significant challenge is the extremely low boiling point of hydrogen; it boils at approximately -253°C. Achieving such low temperatures requires considerable energy.

[0013] To date, several methods exist to enable hydrogen storage. Compressed or liquefied hydrogen is a storage method in which hydrogen gas is kept under pressure to increase storage density. Compressed hydrogen in 350 bar (5,000 psi) and 700 bar (10,000 psi) hydrogen tanks is used in hydrogen tank systems in vehicles. Another form of hydrogen storage involves chemically bonding hydrogen to a carrier. Metal hydrides, ammonia, and liquid organic carriers, as well as others, are being discussed extensively as promising solutions, particularly for mobile hydrogen storage applications.

[0014] Liquid organic compounds that can be used to store hydrogen are called liquid organic hydrogen carriers (LOHCs). These are unsaturated organic compounds that can store a useful amount of hydrogen and release the stored hydrogen on demand. These LOHCs are hydrogenated for storage and dehydrogenated again when hydrogen is needed, for example, for fuel cells. Using LOHCs, a relatively high gravimetric storage density can be achieved (about 7 wt% H2 per LOHC), and the volumetric density is about twice that of H2 at 700 bar, comparable to liquid H2.

[0015] The function of LOHC is described below. The low-energy form of LOHC is reversibly converted to a high-energy form by hydrogenation with hydrogen, which in the reverse reaction recovers hydrogen from the hydrogenation product, accompanied by the formation of the low-energy form, simply by increasing the temperature and / or decreasing the hydrogen pressure. Thus, the reaction is reversible. Reversibility means that the material undergoes conversion from a low-energy dehydrogenated state to an energy-rich hydrogenated state and then back to the low-energy dehydrogenated state without significant loss of LOHC material. In optimal cases, these reversible steps can be repeated indefinitely. The reaction can be carried out in a flow-through reactor, packed-bed reactor, stirred reactor, or batch reactor to produce hydrogen and dehydrated LOHC. In a batch reactor, it is possible to carry out the hydrogenation and dehydrogenation steps with the same amount of LOHC loaded, without the need to reload the LOHC after dehydrogenation.

[0016] In practice, both hydrogenation and dehydrogenation reactions require catalysts. Hydrogenation and dehydrogenation can be carried out in different locations, and in this way, LOHC materials provide a method for transporting energy in the form of hydrogen over longer distances without any loss or consumption of hydrogen or LOHC material. In particular, advantageously usable LOHCs enable this reversible conversion under technically relevant conditions, such as pressure and temperature, which are mentioned as examples.

[0017] Several patents and patent applications have already taught the use of LOHC in connection with fuel cell applications (International Publication No. 2020120261(A1), International Publication No. 2020064222(A1), International Publication No. 2018228895(A1), German Patent Application Publication No. 102017201451(A1), US Patent Application Publication No. 2016061383(AA), German Patent Application Publication No. 102012004444(A1)). LOHC is interpreted to mean the group of chemical materials described in "Energy Environ. Sci.", April 2011, p. 2767, or U.S. Patent Application Publication No. 20100081034(AA), or Huang et al., "J.Am.Chem.Soc," 2009, Vol. 131 (No. 39), pp. 13898-13899, and Fang et al., "J Am.Chem.Soc," 2009, Vol. 131 (No. 42), Nos. 15330-15338, as well as https: / / en.wikipedia.org / w / index.php?title=Liquid_organic_hydrogen_carriers&oldid=1071399187 or https: / / en.wikipedia.org / w / index.php?title=Hydrogen_storage&oldid=1080342247.

[0018] Further LOHC systems are known to date. LOHC systems are often based on cyclic hydrocarbon molecules (Heublein, N. et al., "International Journal of Hydrogen Energy", Vol. 45 (No. 46), 2020, pp. 24902 - 24916, https: / / doi.org / 10.1016 / j.ijhydene.2020.04.274; Kwak et al., "Energy Conversion and Management", 2021, Vol. 239, p. 114124, https: / / doi.org / 10.1016 / j.enconman.2021.114124). First, mention is made of polycyclic aromatic hydrocarbons such as dibenzyltoluene, benzyltoluene, which are currently used as industrial heat transfer liquids, for example, those known under the trade name Marlotherm™, or mixtures of their isomers (Scheme 1).

[0019] [Chemical formula]

[0020] Scheme 1: Special LOHC

[0021] The method and arrangement aim to supply pure hydrogen safely and technically simply to various types of vehicles collectively referred to as "vehicles", such as motor vehicles, buses, large trucks, forklifts, ships, trains, etc. Thus, rather than re-equipping filling stations to operate at very low temperatures or very high pressures at high cost (as in the case of liquid hydrogen), the existing infrastructure is continued to be used, and there is the advantage of storing hydrogen in the form of LOHC, which is much less flammable and much easier to handle compared to compressed or liquefied H2.

[0022] It has been demonstrated that replacing hydrocarbons with heteroatoms such as N and O improves reversible dehydrogenation properties (Xie, Y., Milstein, D., "ACS Appl. Energy Mater," 2019, Vol. 2 (No. 6), pp. 4302-4308, https: / / doi.org / 10.1021 / acsaem.9b00523; Jorschick, H. et al., "Sustainable Energy Fuels," 2021, Vol. 5 (No. 5), pp. 1311-1346, https: / / doi.org / 10.1039 / D0SE01369B). Here, we will discuss the hydrogenation / dehydrogenation of N-ethylcarbazole (NEC). In this case, N-ethylcarbazole (NEC) as a low-energy form is converted to the perhydro form (H12-NEC) as a high-energy form according to the following reaction plan (Scheme 2).

[0023] [ka]

[0024] Scheme 2: Special N-heterocyclic LOHC

[0025] H12-NEC is a liquid that can be stored at ambient temperature and pressure. The storage density of hydrogen produced by this reaction is approximately twice the volume of a 700-bar tank filled with hydrogen. The tank can take any form, as opposed to a pressure vessel, making it easier to accommodate in technical applications.

[0026] Dehydrogenation of LOHCs is an endothermic method that proceeds at a rate only feasible at high temperatures. In any case, the endothermic nature of the dehydrogenation reaction negatively impacts the overall efficiency of the LOHC system: the release of hydrogen from the LOHC requires a continuous supply of energy (heat) to the reactor to maintain the progress of the reaction. Therefore, thermal management in the LOHC system is crucial for heating the LOHC reactor to produce enough hydrogen to be provided for the generation of electricity in the fuel cell. Several approaches exist in this regard. The first approach is direct electric heating of the catalytic element, which includes a catalytic active layer on a heater element or conductive material (U.S. Patent Application Publications 2011265738(A) and 2011268651(A)). In certain designs, the required power is extracted from a fuel cell (US Patent Application Publication No. 2015056526(A)), or the electricity from the fuel cell is used to heat a heat transfer medium connected to the LOHC reactor via a heat exchanger (China Patent Application Publication No. 108940150(A)). Another approach is to install a burner to produce heat by directly burning H2 (Korea Patent Application Publication No. 20210120577(A)) or by burning additives contained in the LOHC fluid, such as biofuels, fossil fuels, methanol, or (bio)ethanol (German Patent Application Publication No. DE102014006430(A1)). Yet another approach is the use of a heat pump (China Patent Application Publication No. 112768724(A)).

[0027] As already explained, the hydrogenation and dehydrogenation methods in the LOHC cycle require suitable catalysts. These catalysts can be heterogeneous or homogeneous. The most well-known catalysts to date are heterogeneous catalysts containing metal particles on an oxide support. The metals are typically selected from the group Ni, Co, Pd, Pt, Rh, Ru, Pd, Ir, and Re, but are not limited to these. Examples of oxide supports include alumina, titania, silica, and ceria. These catalysts can, in principle, be used in both the hydrogenation and dehydrogenation parts of the LOHC cycle, except that Ni is mainly used for hydrogenation. Suitable catalysts can also be obtained by using combinations of metals, alloys, and catalyst supports.

[0028] Noble metal catalysts have a long chemical history for the hydrogenation or dehydrogenation of organic molecules. Heteroatom-doped noble metal catalysts have also been developed. For example, in cyclohexene dehydrogenation, the Pd(111)-P model catalyst has been proposed. The P-modification results in an increased inactivation barrier, thereby improving catalyst stability, leading to less benzene decomposition and a lower rate compared to pure Pd-catalysts (Sampath, A. and Flaherty, DW (2020), "Effects of phosphorus addition on selectivity and stability of Pd model catalysts during cyclohexene dehydrogenation," "Catalysis Science & Technology," Vol. 10 (No. 4), pp. 993-1005). Furthermore, Ouma et al. studied Si, P, S, and Se surface additives as Pt(111) catalytic activity boosters for the dehydrogenation of methylcyclohexane to toluene (Ouma, CN, Obodo, KO, Modisha, PM, and Bessarabov, D. (2022); Si, P, S, and Se surface additives as catalytic activity boosters for the dehydrogenation of methylcyclohexane to toluene ("A liquid organic hydrogen carrier system: Density functional theory insights"; "Materials Chemistry and Physics", Vol. 279, p. 125728).

[0029] In addition, PtP2 nanoparticles on SiO2 exhibit high selectivity but low activity in propene and acetylene hydrogenation, as well as propane dehydrogenation. The P:Pt molar ratio varies from 10 to 50. The catalyst was obtained by impregnating a solid support with Pt and then calcining it at 225°C. The latter was then impregnated with H3PO4, followed by calcination at 600°C, and reduced with hydrogen at 550°C to form a crystalline PtP2 phase, as verified by the characteristic X-ray diffraction pattern of the compound (JTMiller et al., "Structural and Catalytic Properties of Isolated Pt2"). + "Sites in Platinum Phosphide (PtP2)"; "ACS Catalysis", Volume 11 (No. 21) (2021), pp. 13496-13509).

[0030] In addition to Pt, crystalline Ru2P-based catalysts are also known for hydrogenation and dehydrogenation reactions. For the hydrogenation of toluene to methylcyclohexene, crystalline Ru2P supported on SiO2 showed significantly higher activity for this reaction compared to the corresponding Ru catalyst without phosphorus (Furukawa, S.; Matsunami, Y.; Hamada, I.; Hashimoto, Y.; Sato, Y.; Komatsu, T., "Remarkable Enhancement in Hydrogenation Ability by Phosphidation of Ruthenium: Specific Surface Structure Having Unique Ru Ensembles.", "ACS Catal.", 2018, Vol. 8 (No. 9), pp. 8177-8181, https: / / doi.org / 10.1021 / acscatal.8b02582). In this case, the crystallinity of the Ru2P phase was determined by high-resolution transmission electron microscopy (HR-TEM). In contrast, the same document also teaches that the activity of phosphides of Pt, Pd, Ir, and Rh in the hydrogenation of toluene is lower than that of the corresponding catalysts that do not contain phosphorus.

[0031] Similarly, crystalline Ru2P supported on SiO2 is also a known catalyst for the dehydrogenation of propane, as verified by HR-TEM (Ma, R.; Yang, T.; Gao, J.; Kou, J.; Chen, JZ; He, Y.; Miller, JT; "Li, D. Composition Tuning of Ru-Based Phosphide for Enhanced Propane Selective Dehydrogenation." "ACS Catal.", October 2020). Crystalline Ru2P supported on activated carbon has also been shown to be a catalyst for the hydrogenation and dehydrogenation of N-heterocyclic compounds (Shao, F. "Geometric and Electronic Effects on the Performance of a Bifunctional Ru2P Catalyst in the Hydrogenation and Acceptorless Dehydrogenation of N-Heteroarenes." "Chinese Journal of Catalysis," Vol. 10, 2021). Note that the presence of the crystalline Ru2P phase in these catalysts is essential for their catalytic properties.

[0032] Low reactivity, the required high reaction temperature, and the applicable pressure conditions limit the applicability of carbon-containing molecules as hydrogen storage, and are incompatible with, for example, the operating temperatures of conventional PEM fuel cells. Therefore, finding more and better catalysts that will allow for further reductions in the temperature required for hydrogenation / dehydrogenation methods of LOHC-based catalytic systems, in order to make the overall method more energy-efficient and adaptable to fuel cell implementations, for example, remains an objective. Furthermore, the catalysts applied should be stable and robust in use, easy to manufacture, and provide a less complex mode for carrying out hydrogenation and dehydrogenation using LOHC in conjunction with fuel cells for electricity generation, particularly PEMs.

[0033] These and other objectives, which are obvious to those skilled in the art, are achieved by providing the phosphorus-doped PGM type catalyst and the catalyst system comprising the catalyst as described in claims 1 and 7, respectively. Dependent claims of the said claims relate to preferred embodiments of the catalyst / catalyst system. Claims 8 to 12 point to the method of the present invention for producing such catalysts. Claims 13 to 17 relate to the catalyst system of the present invention. Claim 18 relates to an apparatus for generating electricity, and claim 19 protects the use of the catalyst system of the present invention.

[0034] To provide a Lindau platinum group metal (PGM)-type catalyst for the hydrogenation and dehydrogenation of organic hydrogen carrier molecules, especially liquid hydrogen carrier compounds, wherein the catalyst is supported on a solid support material, phosphorus has an average formal oxidation state of 2 or less, and the molar ratio x of PGM:P is 0.1 < x < 10, while not containing a crystalline phosphide phase, where PGM is selected from the group consisting of Pt, Pd, Ru, Ir, Rh, and mixtures thereof. By providing this, the object is achieved in an excellent manner despite being very easy. The oxidation state of phosphorus can be measured by known techniques, for example, by X-ray photoelectron spectroscopy, chemical identification of the phosphorus phase present in the catalyst (Kim, S.S.; Britcher, L.; Kumar, S.; Griesser, H.J., "XPS Study of Sulfur and Phosphorus Compounds with Different Oxidation States.", JSM, 2018, Vol. 47 (No. 8), pp. 1913 - 1922, https: / / doi.org / 10.17576 / jsm-2018-4708-33). The PGM:P ratio can be determined by standard chemical analysis methods well-known to those skilled in the art, such as Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). According to the present invention, by doping a supported PGM-type catalyst with a certain amount of phosphorus atoms, the rate of the dehydrogenation reaction of organic molecules, especially hydrogenation, such as perhydrobenzyltoluene (H12-BT), increases surprisingly and can reach a given degree of dehydrogenation of more than 50% in at least 20% less time. This is almost obvious in light of the known prior art.

Summary of the Invention

Means for Solving the Problems

[0035] In this invention, the PGM catalyst is doped with a certain amount of phosphorus. This results in increased catalytic activity, making it a viable catalyst for the hydrogenation and dehydrogenation of organic hydrogen carrier molecules, particularly liquid organic hydrogen carrier molecules. The formal oxidation state of phosphorus in this type of composition is, on average, phosphate (PO4 3- ) or phosphate (PO3 3- This indicates that when phosphorus is added as a phosphate or phosphate under reducing conditions, it is partially reduced. Since existing PH3 species bonded to the solid PGM surface are known to be unstable at the high temperatures involved, it is considered likely that the reduction will not, on average, reach formal oxidation state -3. Therefore, preferably, the average formal oxidation state of the present phosphorus atoms is somewhere between -3 and 2, most preferably between -2 and 2, and most preferably between 0 and 2.

[0036] It is conceivable that phosphorus dopants can act on PGM-type catalysts by occupying specific positions on the outer sphere of PGM-containing particles, typically on the surface of a high-surface-area solid support material, which is commonly known in the field of heterogeneous catalysts. Phosphorus dopants on the surface of PGM-containing particles can be expected to affect catalytic activity, which, according to the present invention, will be directed toward higher activity. Another possibility is that the phosphorus dopants are directly positioned on a high-surface-area surface, which may hinder the sintering of the PGM particles and thus contribute to the catalytic stability of the phosphorus-doped catalyst.

[0037] The platinum group metal (PGM) catalysts used within the concept of this invention are typical catalysts well known in various applications of heterogeneous catalytic action, such as automotive exhaust treatment catalysts, emission control catalysts for stationary sources, and hydrogenation, dehydrogenation, and oxidation reactions in large-scale chemical methods. Typically, the platinum group metal in question is deposited on a solid support material, such as alumina, titania, ceria, silica, zirconia, and combinations thereof, by methods well known to those skilled in the art ("Heterogeneous Catalysis and Solid Catalysts," Ullmann Encyclopedia 2009, Wiley-VCH Verlag GmbH & Co.KGaA, Weinheim, p. 47 and subsequent pages).

[0038] Solid support materials are materials on which the activated PGM metal particles are placed. These may be powders, powders processed into catalyst products (see the paragraph below), or pre-formed or pre-formed solids ("articles"). All solid support materials in powder form can be used in this case (e.g., "Heterogeneous Catalysis and Solid Catalysts," Ullmann Encyclopedia 2009, Wiley-VCH Verlag GmbH & Co.KGaA, Weinheim, p. 36 and subsequent). Typically, these are high-surface-area metal oxides that are somewhat stable to the high temperatures that may occur in the anticipated reaction. Other types such as carbon, carbides, nitrides, and phosphates are also likely solid support materials in powder form. The size of the powder particles is typically in the range of 0.1 to 500 μm, preferably 1 to 100 μm (ISO 13320-1 - latest version as of the filing date). In particular, the support material is 30 to 250 μm 2 / g, preferably 100-200m 2It has a BET surface area of ​​1 / g (determined according to German standard DIN 66132 - latest version as of the filing date). Preferred materials in this regard include, for example, alumina, alumina / silica mixed oxide, magnesia / alumina mixed oxide, ceria and ceria / zirconia mixed oxide, ceria / alumina mixed oxide, cordierite, silicon carbide, aluminum titanate, cordierite-alumina, silicon nitride, zircon mullite, carbon, spodumene, alumina-silica-magnesia, zirconium silicate, sillimanite, magnesium silicate, zircon, petalite, silicolite, alumina, aluminosilicate, silicon phosphate-aluminum, and similar materials. Most preferred materials are selected from the group consisting of alumina, silica, magnesia, titania, zirconia, ceria, mixtures containing at least two of these materials, and mixed oxides containing at least two of these materials. Mixed oxides are, in particular, solid solutions. The solid support material is most preferably selected from the group consisting of alumina, zirconia, titania, ceria, SiC, AlTi, cordierite, or mixtures or composites thereof. When alumina is used, it is preferably stabilized with, for example, 1 to 6 weight percent, and especially about 4 weight percent, of lanthanum, silica, or barium.

[0039] These powders can be processed into different forms of catalyst products, such as pellets, rings, extruded products like flow-through or wall-flow monoliths, spheres, hollow spheres, and granules. The size of these products typically varies from approximately 1 mm to 5 cm. Such catalyst products may contain pores ("Synthesis of Solid Catalysts"; de Jong, KP (ed.), Wiley-VCH:Weinheim, 2009, Chapter 9). The powder support material may be processed before the addition of the PGM components. In this case, one or more selected platinum group metals are deposited onto such pre-formed solid support material by a method well known to those skilled in the art ("Heterogeneous Catalysis and Solid Catalysts," Ullmann Encyclopedia 2009, Wiley-VCH Verlag GmbH&Co.KGaA, Weinheim, p. 47 and thereafter; "Synthesis of Solid Catalysts"; de Jong, KP (ed.), Wiley-VCH:Weinheim, 2009, Chapters 3-8). In the second step, after the selected platinum group metals have been deposited by a method well known to those skilled in the art, the powder is processed into a catalyst product ("Synthesis of Solid Catalysts"; de Jong, KP (ed.), Wiley-VCH:Weinheim, 2009, Chapters 3-9). PGM-containing solid support materials in powder form can also be processed into catalytic products such as ceramic foams in the size range of 1 to 500 cm, 3D printed forms, and porous ceramic filters (HBFriedrich et al., "Monoliths: A Review of the Basics, Preparation Methods and Their Relevance to Oxidation," Catalysts (2017), Vol. 7, p. 62).In the third step, a solid support material in the form of a powder containing a platinum group metal is processed into a catalyst product, and then the steps referred to herein are combined so that a second portion of the same or different platinum group metal is deposited by a method well known to those skilled in the art ("Synthesis of Solid Catalysts"; de Jong, KP (ed.), Wiley-VCH:Weinheim, 2009, Chapters 3-9).

[0040] In another embodiment, a PGM-containing solid support material in powder form is processed into a catalyst article by applying it to an accessible surface of a preformed article such as a flow-through monolith, wall-flow filter or corrugated monolith, plate, mesh, wire, other preformed body, glass wool, metal wool, etc., known from exhaust treatment catalysts in automotive applications, for example by wash coating, deposition, or any other method designed to fix the solid support material to the outer surface of the solid (Avila et al., "Chem.Eng.J." (2005), Vol. 109, pp. 11-36). The preformed article can, in principle, be any solid material, such as metals, oxide materials, ceramic materials, glass fibers, polymers, etc. Such articles are often based on fibrous or powdered materials that are preformed into a solid by using appropriate binders, coatings, or adhesives (HBFriedrich et al., "Monoliths: A Review of the Basics, Preparation Methods and Their Relevance to Oxidation," Catalysts (2017), Vol. 7, p. 62).

[0041] PGMs can also be directly supported on articles as solid support materials, such as the aforementioned solid preformed articles, forms, and objects. In typical methods for producing such articles, these articles are brought into contact with, for example, a solution of platinum group metals, according to methods well known to those skilled in the art ("Heterogeneous Catalysis and Solid Catalysts," Ullmann Encyclopedia 2009, Wiley-VCH Verlag GmbH & Co.KGaA, Weinheim, p. 47 and subsequent; "Synthesis of Solid Catalysts"; de Jong, KP (ed.), Wiley-VCH:Weinheim, 2009, Chapters 3-8). This measurement results in the PGMs being deposited on the article in small clusters. These are then typically fixed to the outer surface of the article or inside the porous structure of the article by drying and calcination procedures.

[0042] Suitable PGMs for the present invention have been previously identified. In a preferred embodiment, the PGM is Pt and / or Pd. In a very preferred embodiment, Pt is the only PGM used within the scope of the present invention.

[0043] A flow-through monolith has fine parallel gas channels extending from the inlet to the outlet surface of the substrate so that the channels are open for fluid flow. The channels, which are essentially straight paths from the fluid inlet to the fluid outlet, are defined by walls. The catalyst material can be coated as a washcoat so that the flowing gas comes into contact with the catalyst material. The channels of the monolithic substrate are thin-walled channels and may be any preferred cross-sectional shape and size such as trapezoidal, rectangular, square, sinusoidal, hexagonal, elliptical, circular, and others. Such structures may contain about 20 to 900 or more gas inlet openings (i.e., cells) per square inch of cross-sectional area (3 to 140 cells / cm²). 2The wall thickness, i.e., the thickness of the walls separating the channels of the substrate from each other, is typically about 0.005 cm to about 0.3 cm. Flow-through monoliths have a porosity of over 20%, generally 20% to 70%, and particularly 35% to 65% [measured according to DIN 66133, the latest version as of the filing date]. The average pore size is at least 1 μm, e.g., 1.5 μm to 25 μm, preferably greater than 3 μm, and particularly 5 μm to 18 μm [measured according to DIN 66134, the latest version as of the filing date].

[0044] The wall flow filter consists of multiple parallel channels formed by porous walls. These channels are alternately sealed at one of the two ends of the filter, forming channel A, which is open at the first side of the filter and sealed at the second side, and channel B, which is sealed at the first side and open at the second side. For example, fluid flowing into channel A can only leave the filter through channel B, and for this purpose, it must flow through the porous wall between channel A and channel B. The finished substrate has a porosity of more than 40%, generally 40% to 75%, and particularly 45% to 70% [measured according to DIN 66133, the latest version as of the filing date]. The average pore size is at least 7 μm, for example 7 μm to 34 μm, preferably more than 10 μm, and particularly 10 μm to 20 μm [measured according to DIN 66134, the latest version as of the filing date].

[0045] A corrugated monolith consists of alternating layers of flat and corrugated sheets having regular curved folds or grooves (see Figure 2). Channels are created in the corrugated layer of the article by winding or stacking the combined flat and corrugated sheets into a desired shape. In principle, such structures can be made from any material capable of forming, joining, and holding such structures, such as metals, ceramics, paper sheets, polymers, or glass fiber sheets. One or more further processing steps, such as welding, soldering, bonding, coating, or heating, may be required to stabilize the structure. Such corrugated substrates and their manufacture are disclosed in International Publication No. 2010066345(A1), and its teachings can be applied to the present invention without departing from the scope of the claims. A corrugated catalyst article is obtained by applying a catalytically active material on the surface of the channels or within the porous structure of these materials.

[0046] A preferred embodiment of the corrugated catalyst article is a corrugated article based on a glass fiber substrate. The glass fiber substrate preferably has a wall density of at least 50 g / L but no more than 150 g / L, and a porosity of at least 50%. The substrate monolith consists of a sheet of high silica-content glass or a sheet of E-glass fiber. The high silica-content glass sheet may optionally contain a layer of metal oxide such as alumina, silica, TiO2, or diatomaceous earth to stabilize its structure. In the present invention, the phosphorus-doped PGM catalyst according to the present invention, supported on a powder support, is applied to the surface of the corrugated and flat sheets of the article. In another embodiment, the phosphorus-doped PGM catalyst according to the present invention, supported on a powder support, is applied to the inside of the porous structure of the glass fiber material constituting the corrugated and flat sheets of the article. In yet another embodiment, the unsupported PGM metal and phosphorus are applied directly to the corrugated and flat sheets. In a typical method for producing such fiberglass articles, these articles are brought into contact with, for example, a solution of a platinum group metal, according to methods well known to those skilled in the art ("Heterogeneous Catalysis and Solid Catalysts," Ullmann Encyclopedia 2009, Wiley-VCH Verlag GmbH & Co.KGaA, Weinheim, p. 47 and subsequent; "Synthesis of Solid Catalysts"; de Jong, KP (ed.), Wiley-VCH:Weinheim, 2009, Chapters 3-8). This measurement results in the deposition of PGMs on the article in small clusters. The PGM clusters can be fixed to the outer surface of the fiberglass wall or into the porous structure of the fiberglass wall by appropriate drying and firing procedures well known to those skilled in the art.

[0047] The amount of PGM used to support the solid support material or article can be selected by those skilled in the art. Since an excess amount of PGM makes the catalyst very expensive, the amount selected should be as small as possible to ensure sufficient catalytic activity. Typically, the amount of PGM per unit weight of the solid support material is in the range of 0.01 to 8.0% by weight, preferably 0.1 to 6.0% by weight, and most preferably 0.3 to 5.0% by weight.

[0048] PGMs deposited on a solid support material typically exist in small clusters in the nanometer range. In heterogeneous catalysis, the catalytic activity is determined by the total surface area of ​​these small clusters, with larger surface areas leading to higher activity. Small clusters are often preferred in catalysts because they provide a larger surface area and therefore higher catalytic activity. However, there is a lower limit to the diameter of PGM clusters. For particles with a diameter of less than 1-1.5 nm, quantum effects already occur, depending on the metal used, which can lead to a decrease in the expected catalytic activity. Those skilled in the art know which range of diameters for deposited PGM clusters works best for the present invention. For example, a PGM-type catalyst contains PGM clusters on a solid support material with a scale y of 1.0 nm ≤ y ≤ 50 nm. The particle size is determined from the CO adsorption capacity of the catalyst, which is measured by pulsed CO monoxide chemisorption under appropriate conditions for catalysts known to those skilled in the art (Tanabe, T.; Nagai, Y.; Hirabayashi, T.; Takagi, N.; Dohmae, K.; Takahashi, N.; Matsumoto, S.; Shinjoh, H.; Kondo, JN; Schouten, JC; Brongersma, HH, "Low Temperature CO Pulse Adsorption for the Determination of Pt Particle Size in a Pt / Cerium-Based Oxide Catalyst," Applied Catalysis A:General, 2009, Vol. 370 (Nos. 1-2), pp. 108-113, https: / / doi.org / 10.1016 / j.apcata.2009.09.030). Preferably, the diameter y of the deposited PGM-type catalyst is 1.5 nm ≤ y ≤ 20 nm, most preferably 2.0 ≤ y ≤ 10 nm, and most preferably 2.0 ≤ y ≤ 5.0 nm.

[0049] To produce a phosphorus-doped catalyst, PGM clusters immobilized on a solid support material are then brought into contact with a phosphorus species and held under reducing conditions, for example, at 450°C or higher for at least 1 hour, to produce a phosphorus-doped PGM-type catalyst. The phosphorus compound is used in an amount that obtains the above-mentioned molar PGM:P ratio x of 0.1 ≤ x ≤ 10, preferably 0.3 ≤ x ≤ 5, more preferably 0.4 ≤ x ≤ 2, and most preferably 0.5 ≤ x ≤ 1. It is clearly emphasized that the phosphorus-doped PGM-type catalyst does not contain a phosphine phase, such as the XP2 type where X is the above-mentioned PGM. In particular, X-ray diffraction of the catalyst of the present invention does not show the characteristic features of a crystalline PtP2 phase (see Figure 1), indicating the absence of PtP2.

[0050] In addition, the phosphorus-doped PGM type catalyst may contain further accelerator or inhibitor atoms, which are well known to those skilled in the art. These may promote the reduction or oxidation of the organic hydrogen support molecule in question, or inhibit undesirable side reactions, such as the decomposition of the organic hydrogen support. Thus, in a preferred embodiment, the phosphorus-doped PGM type catalyst comprises a further dopant selected from the group consisting of S, Se, and Si, and most preferably S.

[0051] The phosphorus-doped PGM type catalyst of the present invention can be obtained by the first method, where: (i) At least one PGM is supported on a solid support material; (ii) to contact it with a salt or acid of phosphorus oxide; and, (iii) Next, it is treated with a reducing agent at a temperature of ≥450°C.

[0052] Steps (i) and (ii) can be performed sequentially, i.e., (i) first and (ii) second. However, steps (i) and (ii) in the method of the present invention can also be performed simultaneously by contacting the support material with a solution containing a PGM precursor and a salt or acid of phosphorus oxide. Subsequently, the obtained material is treated with a reducing agent at a temperature of 450°C or higher.

[0053] As already indicated, the deposition of at least one type of PGM onto the surface of a solid support material is already readily known to those skilled in the art, for example, from the field of producing catalysts for automotive exhaust treatment applications. Deposition can be advantageously carried out, for example, by initial wetting techniques, wet impregnation, nanoparticle deposition, or deposition precipitation from a solution of PGM (Chattopadhyay, S., "Review on Monolithic Ceramic Catalysts in Different Applications Support Materials, Incorporation Techniques and Physical Properties," Topical Reviews (2005), Vol. 65 (No. 4), p. 179 and thereafter). In a preferred manner, PGM deposition onto the surface region of a solid support material is carried out by incipient wetness impregnation (https: / / en.wikipedia.org / w / index.php?title=Incipient_wetness_impregnation&oldid=946130465) or by precipitation deposition techniques such as deposition (http: / / www.fhi-berlin.mpg.de / acnew / department / pages / teaching / pages / teaching__wintersemester__2006_2007 / koehler_preparation_supported_catalysts_111006.pdf).

[0054] In a typical procedure for deposition and precipitation, for example, an aqueous solution of PGM is brought into contact with a solid support material. By appropriately changing the pH, the PGM becomes insoluble and deposits onto the surface of the solid support material and into the pores of the solid support material. The material is then dried and calcined to fix the PGM to the solid support material. This drying and calcination can be performed by those skilled in the art. The specific calcination temperature depends on the PGM metal, the specific compounds in the precursor solution, and the deposition conditions. Typically, calcination is carried out at 200-600°C, more preferably 250-500°C, and most preferably about 300-450°C. Often, the gas atmosphere in the calcination process is simply air, but this can be modified. Such modifications include the absence or variation of the partial pressure of oxygen and water, and the addition of one or more auxiliary gases such as hydrogen, carbon monoxide, ammonia, NO, methanol, ethanol, or other small organic molecules such as (C1-C3)-alkanes and / or (C1-C3)-alkenes.

[0055] Solutions of PGMs that can be used in this case are well known to those skilled in the art (Preuster, P., Papp, C., and Wasserscheid, P (2017), "Liquid organic hydrogen carriers (LOHCs): toward a hydrogen-free hydrogen economy," Accounts of Chemical Research, Vol. 50 (No. 1), pp. 74-85). In a preferred form, palladium and / or rhodium and / or platinum are used to produce the PGM-type catalyst of the present invention. Examples in the case of palladium include palladium; halides such as palladium chloride; inorganic salts such as palladium nitrates and sulfates; carboxylates such as palladium acetates; and palladium hydroxides, halides; inorganic salts; carboxylates; hydroxides, alkoxides, dinitrodiamminepalladium, and oxides of tetraaminepalladium and hexaaminepalladium. Preferred examples include nitrates and nitrates; carboxylates; and dinitrodiaminepalladium, tetraamminepalladium, and hexaminepalladium. More preferred examples include nitrates (palladium nitrate) and nitrates; carboxylates; and hydroxides of tetraaminepalladium and hexaaminepalladium.

[0056] Examples of platinum include platinum; halides such as platinum bromide and platinum chloride; inorganic salts of platinum such as hexahydroxoates, chloroplatinic acid (H2[PtCl6]), and tetranitrates; carboxylates such as platinum acetate; and hydroxides, halides, inorganic salts, and carboxylates of platinum; as well as hydroxides of tetraamine platinum and hexaamine platinum; alkoxides, dinitrodiammineplatin, and oxides. Preferred examples include chloroplatinic acid (H2[PtCl6]), and nitrates, carboxylates, hydroxides, and hexahydroxoates of dinitrodiammineplatin, tetraammineplatin, and hexaammineplatin. More preferred examples include chloroplatinic acid (H2[PtCl6]), and nitrates, carboxylates, hydroxides, and hexahydroxoates of dinitrodiammineplatin, tetraammineplatin, and hexaammineplatin.

[0057] Examples of rhodium include rhodium; halides such as rhodium chloride; inorganic salts of rhodium such as nitrates, sulfates, hexaammine salts, and hexacyanoates; carboxylates such as rhodium acetate; and hydroxides, alkoxides, and oxides of rhodium. Preferred examples include nitrates and hexaammine salts, and more preferred examples include nitrates, particularly rhodium nitrate. The above-mentioned compounds of platinum group metals (PGM sources or precursors) in the present invention can be used alone or as mixtures of two or more compounds. When mixing PGM sources or precursors, it is preferable to use counterions of the same type.

[0058] PGM-containing materials are prepared by contacting a support material with one or more PGM-containing solutions. The support materials have already been discussed above. For example, after the deposition of one or more PGM particles onto a solid support material by impregnation, initial wet impregnation, or nanoparticle deposition, the material is dried and optionally calcined as described above.

[0059] The next step is to perform phosphorus doping. In one embodiment of the present invention, phosphorus doping is carried out by contacting the PGM-containing material with a phosphorus oxide salt or acid known to those skilled in the art. Preferred compounds in this regard are phosphates, phosphites, or hypophosphites, and ammonium, alkali, alkaline earth, or other metal salts of phosphorus oxides, such as their acids. The acid or salt derived from the phosphorus oxide acid is more preferably selected from the group consisting of phosphoric acid, phosphonic acid (H3PO3), hypophosphorous acid, and diphosphoric acid. In this regard, phosphonic acid and hypophosphorous acid, and their respective salts, are most preferred. These precursors are preferably contacted with the PGM-type catalyst in the form of a solution. The concentration of this solution is such that the required PGM:P ratio (see above) is achieved. Typically, the concentration of the precursor is in the range of 0.01 to 1000 mmol / L, more preferably 0.5 to 100 mmol / L, and most preferably 1 to 10 mmol / L.

[0060] After contact with the aforementioned compounds, the resulting mixture is optionally dried and calcined again to immobilize the phosphorus compound on the PGM-type catalyst. Those skilled in the art will know what temperature is required. Calcination is carried out preferably at 100-800°C, more preferably 200-500°C, and most preferably 300-450°C, under an oxidizing, reducing, or inert gas flow.

[0061] Here, the phosphorus precursor present on the PGM-type catalyst is treated with a reducing agent in the final step to reduce the formal oxidation state of phosphorus to 2 or less, as shown above. This reduction can be carried out according to those skilled in the art (Kou, J. et al. (2021), "Structural and Catalytic Properties of Isolated Pt 2+-Sites in Platinum Phosphide (PtP2), ACS Catalysis, Vol. 11 (No. 21), pp. 13496-13509; Alvarado Rupflin, L. et al., "Platinum group metal phosphides as heterogeneous catalysts for the gas-phase hydroformylation of small olefins," ACS Catalysis (2017), Vol. 7 (No. 5), pp. 3584-3590; Alvarado Rupflin, L. et al., "Platinum group metal phosphides as efficient catalysts in hydroprocessing and syngas-related catalysis," Catalysts (2018), Vol. 8 (No. 3), p. 122). Preferably, this can be done with a reducing agent which is a hydrogen molecule or a compound that produces hydrogen in reaction with a proton. These compounds are well known to those skilled in the art (Beghi, GE, "Review of thermochemical hydrogen production," International Journal of Hydrogen Energy (1981), Vol. 6 (No. 6), pp. 555-566; http: / / en.wikipedia.org / wiki / Hydrogen#Discovery_and_use). In a preferred manner, the reduction is carried out in a hydrogen atmosphere, or in a mixed atmosphere of hydrogen and an inert gas, such as argon or nitrogen.

[0062] The reduction temperature depends on the type of metal and reducing agent used and is known to those skilled in the art. Reduction is carried out at a suitable temperature depending on the reducing agent, typically above 300°C. Preferably, when hydrogen is used, reduction is carried out at a temperature of 450°C or higher. More preferably, reduction is carried out at a temperature of 500°C or higher, and most preferably, the reduction temperature is set to 550°C or higher. The upper limit of the temperature may not seem important, but for efficiency reasons, it should not exceed 700°C, and preferably is 650°C or lower.

[0063] In an exemplary production method, the PGM-type catalyst is first synthesized by impregnating an oxide support (e.g., Al2O3) with, for example, Pt using a suitable precursor (e.g., H2[PtCl6], Pt(NH3)4(NO3)2, etc.). After impregnation (e.g., stirring at room temperature for 16 hours), solvent (H2O) removal, and calcination (e.g., 400°C, 2 hours, air), a subsequent impregnation with, for example, H3PO3 is carried out. After a second impregnation (e.g., stirring at room temperature for 16 hours) and solvent (H2O) removal, the catalyst is reduced, for example, at 600°C with, for example, 10% H2 in N2 for 2 hours.

[0064] Alternatively, the phosphorus-doped PGM type catalyst of the present invention can also be obtained by this method, where: (i) At least one PGM is supported on a solid support material; (ii) Contact it with a compound selected from the group consisting of PH3, alkyl, or arylphosphine; and, (iii) Optionally, contact it with a reducing agent. Contacting the PGM on a solid support material with a phosphorus compound as described above simultaneously results in phosphating and reduction of the PGM. Compounds containing reduced phosphorus can also be obtained in situ by the decomposition of suitable precursor compounds (Sheng, Q.; Li, X.; Prins, R.; Liu, C.; Hao, Q.; Chen, S., "Understanding the Reduction of Transition-Metal Phosphates to Transition-Metal Phosphides by Combining Temperature-Programmed Reduction and Infrared Spectroscopy," Angewandte Chemie International Edition, 2021, Vol. 60 (No. 20), pp. 11180-11183, https: / / doi.org / 10.1002 / anie.202100767; Liu, D.; Li, X.; Wei, L.; Zhang, T.; Wang, A.; Liu, C.; Prins, R., "Disproportionation of Hypophosphite and Phosphite," Dalton). Trans., 2017, Vol. 46 (No. 19), pp. 6366-6378, https: / / doi.org / 10.1039 / C7DT00243B.).

[0065] In another method of the present invention, phosphorus doping is carried out by contacting the PGM-containing material with a compound containing reduced oxidized phosphorus. Organic or inorganic compounds selected from alkylphosphines, arylphosphines, or phosphane (PH3) are preferred. Compounds containing reduced oxidized phosphorus can also be produced in situ by the decomposition of each phosphorus-containing precursor compound, such as sodium hypophosphite (NaH2PO2). The PGM-containing material is contacted with the above-mentioned compound at a temperature of 100-800°C, more preferably 200-600°C, and most preferably 250-450°C. If phosphane is used, additional treatment with a reducing agent is optional. As the reducing agent, hydrogen can be used, as already mentioned in the first production method. In a preferred manner, this reaction is carried out under a hydrogen atmosphere, or under a mixed atmosphere of hydrogen and an inert gas, such as argon or nitrogen. The reaction is carried out at a high temperature of 100°C or higher. More preferably, the reduction is carried out at a temperature of 200-600°C or higher, and most preferably, the reduction temperature is set to 250-450°C or higher. The applicable conditions and materials used for the first method, as already described, also apply to this alternative method with the necessary modifications.

[0066] In an exemplary production method, the PGM-type catalyst is first synthesized by impregnating an oxide support (e.g., Al2O3) with, for example, Pt using a suitable precursor (e.g., H2[PtCl6], Pt(NH3)4(NO3)2, etc.). After impregnation (e.g., stirring at room temperature for 16 hours), solvent (H2O) removal, and calcination (e.g., 400°C, 2 hours, air), the subsequent phosphating-reduction step is carried out. The PGM-containing material is brought into contact with PH3 by, for example, placing it in a tubular furnace containing sodium hypophosphite present in a ceramic boat upstream of the PGM-containing material. The furnace is then heated to 300°C in N2 for 2 hours to decompose the phosphorus-containing precursor and form PH3, which is thought to result in the phosphating and reduction of the PGM-containing catalyst. In this case, a further reduction step is unnecessary.

[0067] In further embodiments, the present invention relates to a catalyst system for the hydrogenation and dehydrogenation of organic hydrogen carrier molecules, particularly liquid hydrogen carrier compounds, which includes: (i) The phosphorus-doped PGM type catalyst of the present invention; (ii) Organic hydrogen carrier molecules; (iii) Optionally, the solvent and This applies to catalytic systems that include [specific components / features].

[0068] Organic hydrogen carrier molecules can store and release hydrogen on demand in the presence of a suitable catalyst. Such molecules are well known to those skilled in the art. An organic hydrogen carrier molecule suitable for the intended purpose has sufficient hydrogenation / dehydrogenation efficiency. Preferably, the organic hydrogen carrier molecule in question should have a minimum hydrogen storage and release capacity of at least 3% by weight, more preferably at least 4% by weight, and most preferably at least 5% by weight under test conditions. By weight percent refers to hydrogen and molecules only.

[0069] In a preferred embodiment, the organic hydrogen carrier molecule is advantageously selected from the group consisting of a hydrocarbon aromatic compound, a heteroaromatic compound, and ketones, esters, carboxylic acids, and CO2. With respect to liquid organic hydrogen carriers, those skilled in the art will know which LOHC compounds work best for the intended purpose, i.e., to establish a catalytic system that enables the preferably reversible hydrogenation and dehydrogenation of LOHCs under technically reasonable conditions.

[0070] LOHCs that can be used in the catalyst system of the present invention have already been disclosed in the prior art. Preferably, as already mentioned, the LOHC used for this purpose should be able to undergo reversible hydrogenation and dehydrogenation within a suitable temperature and pressure range, particularly under conditions (operating conditions) that can be established in a vehicle equipped with a fuel cell. In a more preferred embodiment, the liquid organic hydrogen carrier is selected from the group consisting of saturated or unsaturated cyclic hydrocarbons and optionally contains N and / or O atoms.

[0071] For example, in a more preferred embodiment, the LOHC employed in the catalyst system of the present invention includes hydrocarbon aromatic compounds. The term liquid organic hydrogen carrier also refers to a partially or completely dehydrogenated form. Partially hydrogenated compounds may still have a reasonable H2 capacity. Therefore, when a hydrocarbon compound is referred to as an LOHC in this context, the reaction products that can be hydrogenated from the low-energy (dehydrogenated) form of the compound are also included, as they are essentially the same in this context. For example, in the case of aromatic hydrocarbons, a partially hydrogenated form of such a compound may no longer be chemically an "aromatic" compound. However, since it is a product of the partial hydrogenation of an aromatic compound, it is still considered an aromatic LOHC. The term "hydrocarbon aromatic compound" then refers to a compound that can be obtained by the hydrogenation of an aromatic compound. More preferred compounds in this regard are those mentioned in the Prior Art section. Compounds selected from the group consisting of diarylmethylenes such as toluene, benzyltoluene, and dibenzyltoluene are extremely preferred.

[0072] In a more preferred embodiment, the liquid organic hydrogen carrier comprises a heteroaromatic compound. A partially hydrogenated heteroaromatic compound may still have a reasonable H2 capacity. This is essentially the same thing in this context, but the compound may no longer be chemically an "aromatic" compound. Thus, when we speak of a heteroaromatic compound as an LOHC in this context, the possible reaction products of the hydrogenation of such heteroaromatic compound are also included. The phrase "heteroaromatic compound" stipulates the fact that it can be obtained by hydrogenation of hydrocarbons and heteroaromatic systems composed of at least one heteroatom such as N, O, and S.

[0073] In a more preferred embodiment, the compounds for hydrogen storage in organic molecules that enable reversible dehydrogenation and hydrogenation in the catalyst system of the present invention are ketones, esters, carboxylic acids, CO2, and C3-C3 compounds such as acetone, butanone, or acetophenone. 10Ketones, formates, acetates, or propionates in which the ester substituents are organils such as alkyl or aryl such as methyl, ethyl, propyl, benzyl, phenyl, or naphthyl, C1-C 10 esters, C1-C such as formic acid, acetic acid, or benzoic acid 10 carboxylic acids are particularly preferred. LOHC systems such as dibenzyltoluene (DBT) / H18-DBT, toluene / methylcyclohexane, pyridine / piperidine, N-ethylcarbazole (NEC) / H12-NEC, CO2 / methanol, CO2 / formic acid, acetone / isopropanol are most preferred. Most preferred in the present invention are LOHC compounds selected from the group consisting of acetone / isopropyl alcohol, perhydro-benzyltoluene / benzyltoluene, perhydrodibenzyltoluene / dibenzyltoluene, N-ethylcarbazole (NEC) / H12-NEC.

[0074] In this regard, compounds that can theoretically be hydrogenated and dehydrogenated in the catalyst system of the present invention but provide too many side reactions during these cycles or cannot be managed in the catalyst system for other reasons such as low fluidity are not included in the definition of LOHC according to the present invention. In particular, instability (side reactions or decomposition under working conditions) due to either thermal or chemical means, for example, reaction with H2O, O2, PGM-type catalysts. According to the present invention, in reversible hydrogenation and dehydrogenation, advantageous organic hydrogen carrier molecules can undergo 5000 cycles under test conditions, but maintain at least 50%, more preferably at least 70%, and most preferably at least 90% of the H2 storage / release capacity compared to a fresh catalyst system under the same conditions.

[0075] Preferably, for example, aldehydes are excluded from the definition of LOHC compounds according to the present invention, especially those that may easily react with themselves and are thus not suitable for use in the reversible hydrogenation / dehydrogenation reactions required for this purpose.

[0076] The solvent that may optionally be present in the catalytic system is one that dissolves the LOHC to the required extent and remains in a liquid state under the operating conditions. For example, due to lower reaction temperatures, certain OHC molecules may become solid or at least waxy, and therefore unsuitable for use as hydrogen carrier molecules. In order to carry out the reaction in a liquid state, the addition of a solvent that plays a role in keeping the OHC molecules in a liquid state may be important. In principle, all solvents well known to those skilled in the art that dissolve each OHC to the required extent and behave inertly under the applicable reaction conditions can be used here. Useful solvents are selected from the group consisting of linear, branched, or cyclic alkanes such as pentane, hexane, heptane, or octane. Aromatic molecules such as benzene or toluene are also possible. In addition, ketones such as acetone and MIBK can be used. Alcohols, ethers, esters, haloalkanes, DMSO, or DMF can also be considered in this regard.

[0077] In this sense, the components of the catalyst system are mixed together in their respective compartments, heated to a preferred temperature, and thereby dehydrogenated. As compartments, airtight tanks, beakers, containers, etc., with fluid connections to devices for H2 consumption or storage can be used. A certain hydrogen pressure may be present, but it is preferably not necessary to apply excessive H2 pressure for dehydrogenation. The temperature of this reaction is advantageously varied between -40°C and 350°C, more preferably between 100°C and 320°C, and most preferably between 180°C and 280°C. Hydrogenation occurs under a specific H2 pressure, preferably between 0.01 and 200 bar, more preferably between 0.1 and 100 bar, and most preferably between 10 and 50 bar. The hydrogenation temperature is varied between -40°C and 300°C, more preferably between 100°C and 300°C, and most preferably between 150°C and 250°C. The above temperature and hydrogen pressure conditions are referred to as the working conditions according to the present invention.

[0078] As already shown, the catalyst system is a heterogeneous mixture containing the components of the catalyst system. The envisioned system should be adapted to the conditions necessary for its intended purpose, i.e., technically reasonable conditions, such as operating conditions, particularly those present in fuel cell-powered vehicles, to establish a catalyst system that enables the reversible hydrogenation and dehydrogenation reactions of organic hydrogen carriers.

[0079] In further embodiments, the present invention relates to an apparatus for generating electricity, comprising a fuel cell and the catalyst system of the present invention. Such an apparatus for generating electricity preferably comprises a reactor containing the catalyst system of the present invention, preferably a system for heating the reactor, optionally a system for separating hydrogen from an organic hydrogen carrier, and optionally one or more heat exchangers. In one embodiment, the system for heating the reactor comprises a burner for burning hydrogen. (Niermann, M. et al., "Energy Environ. Sci.", 2019, Vol. 12 (No. 1), pp. 290-307; http: / / doi.org / 10.1039 / C8EE02700E). In another embodiment, the system for heating the reactor comprises one or more electrically heated bodies, such as plates or meshes, connected to an external power source such as a battery or a generator. In further embodiments, the electric heating body is connected to a fuel cell, and the fuel cell supplies power to the heating system.

[0080] Preferred embodiments of the catalyst system according to the present invention are applicable to apparatus with necessary modifications. In a very preferred embodiment, the catalyst system of the present invention functions in a one-pot compartment (e.g., European Patent No. 3221256(B1)) in which hydrogenation and dehydrogenation reaction steps are alternately carried out by changing reaction conditions such as hydrogen partial pressure or temperature.

[0081] In a further third embodiment of the present invention, the use of the catalyst system of the present invention is claimed. The catalyst system of the present invention is used to supply hydrogen to a fuel cell for generating electricity. Preferably, the hydrogen is supplied in a purified form, for example, as required for use in a PEM fuel cell. Preferred embodiments of the catalyst system and apparatus are also applicable to the use of the present invention with necessary modifications.

[0082] LOHC catalyst systems for releasing hydrogen for fuel advantageously include, for example, (1) a tank containing hydrogen-rich LOHC liquid, (2) a second tank containing dehydrogenated LOHC liquid, (3) a dehydrogenation reactor, (4) equipment for heating the reactor, such as a hydrogen burner, oil heater, or electric heater, (5) equipment for purifying the hydrogen product gas, typically including a cooler or heat exchanger for cooling the product, and (6) a gas-oil separation unit. The purified hydrogen gas is then supplied to a fuel cell to produce electricity (Niermann, M. et al., "Energy Environ. Sci.", 2019, Vol. 12 (No. 1), pp. 290-307; http: / / doi.org / 10.1039 / C8EE02700E; Preuster, P. et al., "J. Hydrog. Ener.", 2018, Vol. 43 (No. 3), pp. 1758-1768).

[0083] This invention relates to the storage and release of hydrogen in an organic liquid. For example, a complete cycle using an LOHC consists of (1) hydrogenation of the dehydrogenated form of the LOHC system using hydrogen gas, and (2) dehydrogenation of the hydrogenated form of the LOHC in a catalytic system. Thus, hydrogen is stored as the hydrogenated form of the LOHC. The hydrogenated form of the LOHC has a higher energy density per unit volume than compressed or liquefied hydrogen, is easier to transport or store due to the lower flammability of the organic liquid, and is safer to handle. The catalytic system of this invention allows those skilled in the art to carry out the expected release and storage of hydrogen at much lower temperatures, and is therefore useful for a technically applicable solution for mobile vehicles equipped with fuel cells for generating electricity. This was not evident from the prior art. [Brief explanation of the drawing]

[0084] [Figure 1] X-ray diffraction patterns of an Al2O3 support, 3.1 wt% Pt / Al2O3 (reduced at 600°C), and phosphorus-doped Pt-P catalysts (all reduced at 600°C). XRD was measured at 10–90°, with a step size of 0.0170 and a time of 100 seconds per step. The diffraction pattern of the P-doped Pt catalyst shows features of γ-Al2O3 that overlap with Pt, but the characteristic features of PtP2 are not observed. This includes reference data for Al2O3 (Gutierrez, G.; Taga, A.; Johansson, B., "Theoretical structure determination of gamma-(Al2O3)"; Physical Review, 3rd series. "B-Condensed Matter" (18, 1978-), 2002, Vol. 65, 012101 / 1-012101 / 4), Pt (Bredig, G; Allolio, R; "Roentgenuntersuchungen an katalytisch wirkenden Metallen," Zeitschrift fuer Physikalische Chemie (Frankfurt Am Main), 1927, Vol. 126, pp. 41-71), and PtP2 (Wyckoff, RWG, "The second edition of Structure of Crystals," The Chemical Catalog Company Inc., New York, 1931, Vols. 234 and 238). [Figure 2] Figures 2a-2c. Top: Corrugated glass fiber showing alternating flat and corrugated layers. Bottom left: Catalyst article obtained by winding flat and corrugated sheets together. In this example, the corrugated structure is made of metal. Bottom right: Catalyst article obtained by stacking flat and corrugated sheets of glass fiber paper. [Figure 3]A batch setup for the dehydrogenation of perhydrobenzyltoluene. This setup consists of a 100 mL three-neck round-bottom flask with a magnetic stirrer (1), a heating mantle (2), a magnetic stirrer plate (3), and a two-neck attachment (4) for Ar supply and for storing the catalyst (5) during the heating / deactivation step. One neck of the flask is used for sampling through a thermocouple and partition (6). The released hydrogen is guided through a reflux condenser (7) and a bubbler (8) before the hydrogen is guided to exhaust. [Modes for carrying out the invention]

[0085] [Examples] material The Al2O3 support material is UmicoreNV / SA (BET surface area 150m²). 2 / g, pore size 13.7nm, total pore volume 0.490g / cm³ 3 ), or Sasol (Puralox, BET surface area 136m²) 2 / g, pore size 13.7nm, total pore volume 0.466g / cm³ 3 Provided by one of the following:

[0086] I purchased chloroplatinate hexahydrate (H2[PtCl6]6H2O, 38-40% Pt) from abcr GmbH.

[0087] Sodium hypophosphate monohydrate (NaH2PO2·H2O), phosphonic acid (H3PO3), and GC-grade acetone (Suprasolv) were purchased from Merck KGaA.

[0088] Example 1 This example demonstrates that an active catalyst for LOHC dehydrogenation can be obtained by the method of the present invention.

[0089] Catalyst A was prepared by synthesizing Pt / Al2O3 in the first step by mixing an Al2O3 support with equal amounts of aqueous H2[PtCl6] (pH=4) to obtain a 3 wt% Pt / Al2O3 catalyst. The suspension was stirred overnight at room temperature (300 rpm, 16 hours). The solvent was then removed using a rotary evaporator (80°C, 100 mbar), and the dried catalyst was then calcined in a muffle oven at 400°C for 2 hours under a flow of air (heating rate 10°C / min). A portion of this catalyst was then reduced in 10% H2 / N2 at 440°C for 2 hours to obtain 3.0 wt% Pt / Al2O3 (Catalyst A - red).

[0090] Another portion of catalyst A is impregnated with phosphonic acid (H3PO3) in a second impregnation step to form catalyst B. Here, Pt / Al2O3 is suspended in deionized water, and then P-precursor H3PO3 is added in the respective amounts to obtain a 0.9 wt% load. The mixture is stirred overnight at room temperature (300 rpm, 16 hours). The solvent is then removed using a rotary evaporator (80°C, 100 mbar), and the dried catalyst is then reduced in 10% H2 / N2 at 600°C for 2 hours. The catalyst contains 2.9 wt% Pt and 0.8 wt% P, which corresponds to a Pt:P molar ratio of 0.58.

[0091] A glass batch setup was used to test the performance of the catalyst powder in the dehydrogenation of perhydro-benzyltoluene (H12-BT) (Figure 3). In the experiment, 15.00 g of H12-BT and 250 mg of catalyst were placed in the setup, resulting in an H12-BT:Pt molar ratio of 2000:1. The reaction temperature was adjusted to 250°C. After 360 minutes of reaction, a liquid sample (approximately 0.5 mL) was taken, and the degree of dehydrogenation (DoDh) of the liquid phase was measured by refractive index. The hydrogen production rate could be calculated from DoDh.

[0092] [Table 1]

[0093] For catalyst A-red, the total amount of hydrogen produced after 6 hours was 69g. H2 / g Pt For catalyst B, the total amount of hydrogen produced after 6 hours was 85g. H2 / g Pt This corresponds to a 23% increase in total hydrogen production in the P-doped catalyst (catalyst B).

[0094] Example 2 This example shows a reduction in the formation of methylfluorene, an indicator of LOHC decomposition by the Pt-P catalyst prepared by the phosphating method of the present invention, compared to non-phosphated Pt / Al2O3.

[0095] Catalyst A-Red was prepared as described in Example 1.

[0096] Catalyst C was prepared by placing 1 g of unreduced Pt / Al2O3 (Catalyst A from Example 1) into a ceramic boat in a tubular furnace. Upstream, 250 mg of NaH2PO2H2O was placed into another ceramic boat. The furnace was then heated to 300°C at a rate of 10°C / min in pure N2 and maintained at this temperature for 2 hours. Here, the NaH2PO2 decomposes into Na2HPO4 and PH3, the latter of which should reduce the Pt / Al2O3 catalyst and simultaneously modify it with phosphorus. The catalyst contains 2.5 wt% Pt and 0.4 wt% P, corresponding to a Pt:P ratio of 1.0.

[0097] The performance of the catalyst powder in the dehydrogenation of perhydro-benzyltoluene (H12-BT) was tested as described in Example 1. The liquid phase was analyzed using gas chromatography (GC-FID) to determine the methylfluorene content.

[0098] [Table 2]

[0099] For catalyst A-red, the total methylfluorene content in the liquid phase after 6 hours was 0.43%, and for catalyst C, the total methylfluorene content in the liquid phase after 6 hours was 0.36%. This corresponds to a 16% reduction in methylfluorene formation by the P-doped catalyst (catalyst C).

[0100] Example 3 This example demonstrates the effect of reduction temperature on the performance of a Pt-P / Al2O3 catalyst prepared by the method of the present invention in H12-BT dehydrogenation.

[0101] A portion of catalyst A (prepared as described in Example 1) was reduced in 10% H2 / N2 at 440°C for 2 hours to obtain 3.0 wt% Pt / Al2O3 (catalyst A-440), and another portion was reduced in 10% H2 / N2 at 600°C for 2 hours to obtain 3.1 wt% Pt / Al2O (catalyst A-600).

[0102] A catalyst was prepared as described in Example 1 (Catalyst B), which contained 2.7 wt% Pt and 0.6 wt% P (Catalyst B-600). Another catalyst was prepared as described in Example 1 (Catalyst B), but reduced at 440°C instead of 600°C to obtain a catalyst (Catalyst B-440) having 3.0 wt% Pt and 0.6 wt% P, which corresponded to a Pt:P molar ratio of 0.8.

[0103] The performance of the catalyst powder in the dehydrogenation of perhydro-benzyltoluene (H12-BT) was tested as described in Example 1.

[0104] [Table 3]

[0105] For catalysts A-440 and A-600, the total amount of hydrogen produced after 6 hours was 56g and 33g, respectively. H2 / g Pt The results were as follows: For catalysts B-440 and B-600, the total amount of hydrogen produced after 6 hours was 19g and 81g, respectively. H2 / gPt This corresponds to a 45% (compared to A-440) and 145% (compared to A-600) increase in total hydrogen production in the P-doped catalyst (B-600) reduced at 600°C. On the other hand, the P-doped catalyst (B-440) reduced at 440°C shows a 66% lower hydrogen production rate compared to catalyst A-440.

[0106] Example 4 This example demonstrates the effect of the Pt:P ratio on the performance of a Pt-P / Al2O3 catalyst in H12-BT dehydrogenation.

[0107] Catalysts with different P loadings are prepared by adjusting the precursor ratio as described in Example 1 (Catalyst B) to reach final Pt:P ratios of 1.75 (Catalyst B-1.75), 0.99 (Catalyst B-0.99), 0.58 (Catalyst B-0.58), and 0.40 (Catalyst B-0.40), respectively.

[0108] The performance of the catalyst powder in the dehydrogenation of perhydro-benzyltoluene (H12-BT) was tested as described in Example 1.

[0109] [Table 4]

[0110] Catalyst B-0.58 achieves the highest hydrogen production within a reaction time of 360 minutes compared to other phosphorus-modified catalysts with lower and higher P content.

[0111] Example 5 This example demonstrates that, in the hydrogenation reaction of benzyltoluene (H0-BT) to perhydrobenzyltoluene (H12-BT), the phosphorus-modified Pt catalyst prepared by the method of the present invention exhibits increased activity compared to an unphosphorusted Pt catalyst.

[0112] Catalyst AH was prepared as described in Example 1 (Catalyst A - Red, 3 wt% Pt), and catalyst BH was prepared as described in Example 1 (Catalyst B, 3 wt% Pt, 0.6 wt% P).

[0113] To test the performance of a catalyst powder in the hydrogenation of benzyltoluene (H0-BT) to perhydrobenzyltoluene, an autoclave was filled with 0.8 moles of H0-BT and a catalyst amount corresponding to a Pt concentration of 0.04 mol%. The temperature was raised to 210°C and a hydrogen pressure of 30 bar was applied. To track the progress of the reaction, the degree of hydrogenation (DoH) of the liquid phase was measured by gas chromatography by taking a liquid sample from the autoclave reactor during the reaction. As a measure of activity, the time required to reach 99% DoH was compared.

[0114] [Table 5]

[0115] For catalysts A through H, the time required to reach 99% DoH is 30 minutes, while for catalysts B through H, it is 7.5 minutes. This is equivalent to four times the acceleration of the hydrogenation reaction using P-doped catalysts (catalysts B through H).

Claims

1. A phosphorus-doped PGM type catalyst for the hydrogenation and dehydrogenation of organic hydrogen carrier molecules, particularly liquid hydrogen carrier compounds, wherein the catalyst is supported on a solid support material, the phosphorus has an average formal oxidation state of 2 or less, and the molar ratio x of PGM:P is 0.1 ≤ x ≤ 10, but does not contain a crystalline phosphide phase, and the PGM is selected from the group consisting of Pt, Pd, Ru, Ir, Rh, and mixtures thereof.

2. The solid support material is selected from the group consisting of alumina, zirconia, titania, ceria, SiC, AlTi, cordierite, or mixtures or composites thereof. The phosphorus-doped PGM type catalyst according to claim 1.

3. The PGM is characterized in that it is Pt and / or Pd. The phosphorus-doped PGM type catalyst according to claim 1.

4. The amount of PGM per solid support material is characterized in being within the range of 0.01 to 8% by weight. The phosphorus-doped PGM type catalyst according to claim 1.

5. The PGM-type catalyst is characterized in that it contains PGM on the support with a scale y of 1.0 nm ≤ y ≤ 50 nm. The phosphorus-doped PGM type catalyst according to claim 1.

6. The PGM:P molar ratio x is characterized in that 0.3 ≤ x ≤ 5. The phosphorus-doped PGM type catalyst according to claim 1.

7. The catalyst is characterized by comprising a further dopant selected from the group consisting of S, Se, and Si. The phosphorus-doped PGM type catalyst according to claim 1.

8. The following steps: (i) supporting at least one PGM on a solid support material; (ii) bringing it into contact with a phosphorus oxide salt or acid; (iii) Next, it is treated with a reducing agent at a temperature of ≥300°C, A method for producing a phosphorus-doped PGM type catalyst according to any one of claims 1 to 7, comprising:

9. The acid or salt derived from the acid of the phosphorus oxide is selected from the group consisting of phosphoric acid, phosphonic acid, hypophosphorous acid, and diphosphate. The method according to claim 8.

10. The reducing agent is characterized by being a hydrogen molecule or a compound that generates hydrogen in reaction with a proton. The method according to claim 8.

11. The reduction temperature is set to 550°C or higher. The method according to claim 8.

12. The following steps: (i) supporting at least one PGM on a solid support material; (ii) That, PH ３ Contacting with a compound selected from the group consisting of alkyl or arylphosphine; (iii) Selectively bringing it into contact with a reducing agent, A method for producing a phosphorus-doped PGM type catalyst according to any one of claims 1 to 7, comprising:

13. A catalyst system for the hydrogenation and dehydrogenation of organic hydrogen carrier molecules, particularly liquid hydrogen carrier compounds, the following: (i) a phosphorus-doped PGM type catalyst according to any one of claims 1 to 7; (ii) Organic hydrogen carrier molecules; (iii) Optionally, the solvent and A catalyst system including the following.

14. The organic hydrogen carrier is selected from the group consisting of saturated or unsaturated cyclic hydrocarbons, and optionally contains N and / or O atoms. The catalyst system according to claim 13.

15. The organic hydrogen carrier molecule is characterized in that it is a liquid organic hydrogen carrier containing a hydrocarbon aromatic compound. The catalyst system according to claim 13.

16. The aforementioned organic hydrogen carrier molecule is characterized by being a liquid organic hydrogen carrier containing a heteroaromatic compound. The catalyst system according to claim 13.

17. The aforementioned organic hydrogen support is a ketone, ester, carboxylic acid, CO ２ Characterized by comprising a compound selected from the group consisting of, The catalyst system according to claim 13.

18. An apparatus for generating electricity, comprising a fuel cell and the catalyst system described in claim 13.

19. Use of the catalyst system according to claim 13 for supplying hydrogen to a fuel cell for generating electricity.

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