Process for producing a hydrogen product

Abstract

A method for producing hydrogen products from ammonia, comprising the following steps: - providing an ammonia feed stream; - feeding the ammonia feed stream to at least one ammonia pre-cracking reactor to produce a partially converted ammonia feed stream comprising ammonia, hydrogen, and nitrogen through a pre-cracking reaction, the pre-cracking reactor comprising a pre-cracking catalyst bed comprising 20% ​​to 60% by weight of nickel, preferably 25% to 50% by weight of nickel as a pre-cracking catalytic active material; - feeding the partially converted ammonia feed stream to an ammonia cracking reactor to produce an effluent gas stream comprising hydrogen, nitrogen, and optionally unconverted ammonia through a cracking reaction, the cracking reactor comprising a cracking catalyst bed comprising 10% to 20% by weight of nickel as a cracking catalytic active material.

Description

[0001] The field of this invention is a method for producing hydrogen products from ammonia. This invention also relates to a system for producing hydrogen products from ammonia.

[0002] The production of hydrogen products via endothermic cracking of ammonia feedstock can be carried out in a cracking reactor at elevated temperatures. Such a cracker typically comprises a metal shell, catalyst, and an external heat source. This method requires a significant amount of heat and energy. The production of hydrogen-containing effluent gas products via endothermic cracking of an ammonia feedstock can be carried out in a catalytic unit at elevated temperatures, typically between 400°C and 800°C. To achieve the lowest possible CO2 footprint for this cracking method, an external heat source is provided by the combustion of the ammonia fuel feedstock in the furnace. Heat is transferred to the catalyst that promotes the cracking reaction, which requires a significant amount of heat and energy to facilitate the reaction. If the temperature is too low for the catalyst to promote the cracking reaction, the ammonia conversion rate is significantly reduced. The disadvantages of this method are its requirement for significant external energy and the potential for low ammonia feedstock conversion. These pose challenges to the scalability of this method.

[0003] A system for producing hydrogen from ammonia, comprising an adiabatic pre-cracking reactor and a subsequent cracking reactor, is known from the prior art. Such a system operates with the same iron-based catalyst in both the pre-cracking reactor and the cracking reactor. This iron-based catalyst is preferred due to its low cost, but it forms iron nitrides when contacted with ammonia at temperatures above 500°C. The pre-cracking reactor operates at a lower temperature and can serve as an initial step in the process to convert a portion of the ammonia, thereby protecting the iron-based catalyst in the downstream cracking reactor, which operates at a higher temperature.

[0004] There is a need to improve the yield of the hydrogen production reaction from ammonia at a reasonable cost.

[0005] One object of the present invention is to improve hydrogen production in order to increase the yield of the pre-cracking and cracking stages and reduce the cost of the production method.

[0006] Therefore, the present invention proposes a system for producing hydrogen products from ammonia, comprising:

[0007] - At least one pre-cracking reactor arranged to receive an ammonia feed stream to produce a partially converted ammonia feed stream comprising ammonia, hydrogen, and nitrogen, said at least one pre-cracking reactor comprising a pre-cracking catalyst bed containing 20% ​​to 60% by weight nickel, preferably 25% to 50% by weight nickel as the pre-cracking catalytic active material.

[0008] - At least one ammonia cracking reactor arranged to receive the partially converted ammonia feed stream to produce an effluent gas stream comprising hydrogen and nitrogen and optionally unconverted ammonia, the ammonia cracking reactor comprising a cracking catalyst bed comprising 10% to 20% by weight of nickel as a cracking catalytic active material.

[0009] One advantage of this invention is that the adjusted nickel content of both the pre-cracking catalyst and the cracking catalyst enables high catalytic activity, resulting in high reaction rates in the pre-cracking reactor and ammonia cracking reactor systems of this invention. Furthermore, nickel exhibits good kinetics at a reasonable cost.

[0010] According to one aspect of the invention, the pre-cracked catalyst bed comprises a pre-cracked support, wherein the pre-cracked catalytically active material is mounted on the pre-cracked support. Specifically, the pre-cracked support comprises a material selected from MgO and CaO (Al₂O₃). n Materials containing MgAl2O4, Al2O3, and ZrO2.

[0011] According to one aspect of the invention, a precracked catalyst bed comprises a plurality of precracked catalyst particles, which include a precracked support and a precracked catalytic active material on the precracked support.

[0012] According to one aspect of the invention, a cracking catalyst bed comprises a cracking support, on which the cracking catalytically active material is placed. Specifically, the cracking support comprises a material selected from Al₂O₃, particularly α-Al₂O₃, CalAl₂O₄, particularly α-CalAl₂O₄, K / CaAl₂O₄, α-K / CaAl₂O₄, CaK₂Al₂O₃⁴, and MgAl₂O₄.

[0013] According to one aspect of the invention, a cracking catalyst bed comprises a plurality of cracking catalyst particles, which include a cracking support and a cracking catalytic active material on the cracking support.

[0014] The selected supports for both the pre-cracked catalyst bed and the cracked catalyst bed improve the stability of the catalyst bed and thus improve the reaction efficiency.

[0015] Catalytic activity, particularly in relation to the differences in catalytic activity when comparing two different catalysts, is understood as the degree of conversion from feedstock to product achieved per unit length of catalyst bed. Activity is influenced by the chemical composition of the catalyst bed (catalytically active material and support material), doping (introducing components into the support material that alter its original properties), available surface area, etc., as well as the geometry (e.g., shape) and textural parameters (e.g., porosity or loading) of the catalyst particles.

[0016] According to one aspect of the invention, the metal surface area of ​​the pre-cracked catalyst particles is higher than that of the cracked catalyst particles. In particular, the metal surface area of ​​the pre-cracked catalyst particles is 50% or 25% higher than that of the cracked catalyst particles.

[0017] According to one aspect of the invention, the metal surface area of ​​the pre-cracked catalyst particles is 10 m². 2 .g -1 up to 35 m 2 .g -1 between.

[0018] According to one aspect of the invention, the metal surface area of ​​the cracking catalyst particles is 2 m². 2 .g -1 Up to 4 m 2 .g -1 between.

[0019] According to one aspect of the invention, the nickel dispersion in the pre-cracked catalyst pellets is between 3% and 9%.

[0020] According to one aspect of the invention, the nickel dispersion in the cracking catalyst pellets is between 3% and 6%.

[0021] According to one aspect of the invention, the average nickel crystallite size in the pre-cracked catalyst particles is between 10 nm and 30 nm.

[0022] According to one aspect of the invention, the average nickel crystallite size in the cracking catalyst pellets is between 15 nm and 40 nm.

[0023] According to one aspect of the invention, the metal surface area of ​​the precracked catalyst pellets, the nickel dispersion in the precracked catalyst pellets, and / or the average nickel crystallite size in the precracked catalyst pellets are measured by hydrogen chemisorption analysis, wherein the metal surface area, nickel dispersion, and / or average nickel crystallite size are determined by hydrogen adsorption isotherms, particularly according to the ASTM D3908-20 standard procedure.

[0024] According to one aspect of the invention, the metal surface area of ​​the cracking catalyst pellets, the nickel dispersion in the cracking catalyst pellets, and / or the average nickel crystallite size in the cracking catalyst pellets are measured by hydrogen chemisorption analysis, wherein the metal surface area, nickel dispersion, and / or average nickel crystallite size are determined by hydrogen adsorption isotherms, particularly according to the ASTM D3908-20 standard procedure.

[0025] Specifically, prior to the hydrogen chemisorption measurement, the pre-cracked catalyst or cracking catalyst is degassed under vacuum at a temperature rate of 1 to 10 °C / min between 150 and 250 °C, and then held in this state for 1 to 2 hours. The degassed pre-cracked catalyst is then reduced at 350 to 450 °C, or the degassed cracking catalyst is reduced at 450 to 600 °C, by passing pure hydrogen through it at a temperature rate of 1 to 10 °C / min. The pre-cracked catalyst or cracking catalyst is then held in this state for 1 to 2 hours. The pre-cracked catalyst or cracking catalyst is then evacuated under vacuum at a temperature similar to that of the reduction for 1 to 2 hours to remove the adsorbed hydrogen from the surface.

[0026] The pre-cracked catalyst or cracked catalyst is then cooled to 40°C to reach the temperature used for hydrogen chemisorption measurements. Hydrogen is then incrementally titrated onto the catalyst at 40°C, with the pressure recorded after each pressure increment, allowing sufficient time for equilibrium to be reached.

[0027] Specifically, the ASTM D3908-20 standard is used for calibration.

[0028] According to one aspect of the invention, the porosity of the pre-cracked catalyst pellets is higher than that of the cracked catalyst pellets.

[0029] According to one aspect of the invention, the specific surface area of ​​the pre-cracked catalyst particles is higher than that of the cracked catalyst particles.

[0030] Metallic surface area refers to the surface area of ​​the granules in contact with reactants (e.g., ammonia). The porosity of the granules of this invention imparts an increased active surface area and thus improved reaction efficiency.

[0031] According to one aspect of the invention, the pre-cracking catalyst pellets and the cracking catalyst pellets have a shape selected from spherical or cylindrical.

[0032] According to one aspect of the invention, the cracking catalyst pellet shape includes at least one pore penetrating each of the pellets.

[0033] According to one aspect of the invention, the cracking catalyst pellets have a cylindrical shape with a rounded tip and / or a corrugated cylindrical shape.

[0034] These shapes of cracking catalyst pellets are advantageous in ammonia cracking reactors, where there is more pressure drop limitation than in pre-cracking reactors.

[0035] According to one aspect of the invention, the pre-cracked catalyst pellet shape does not include pores penetrating each of the pellets.

[0036] The shapes of the pre-cracked pellets and cracked pellets of the present invention increase the heat exchange between the catalyst and ammonia, and are selected based on the typical pressure drops occurring in the pre-cracked reactor and ammonia cracking reactor, respectively. This results in an improved reaction.

[0037] According to one aspect of the invention, each cracking catalyst pellet has a cylindrical shape with a diameter of 8 mm to 20 mm and a length of 8 mm to 20 mm.

[0038] According to one aspect of the invention, each pre-cracked catalyst pellet has a cylindrical shape with a diameter of 3 mm to 6 mm and a length of 3 mm to 6 mm.

[0039] According to one aspect of the invention, the at least one pre-cracking reactor is an adiabatic pre-cracking reactor.

[0040] According to one aspect of the invention, the system includes at least one heat exchanger upstream of the pre-cracking reactor, said heat exchanger being arranged to preheat the ammonia before it enters the pre-cracking reactor. Such a heat exchanger is also referred to as a preheater.

[0041] According to one aspect of the invention, the pre-cracking reactor includes an inlet arranged to receive preheated ammonia and an outlet arranged to release partially converted ammonia feed stream.

[0042] According to one aspect of the invention, a heat exchanger is arranged to preheat the ammonia feed stream at a temperature between 350°C and 650°C, preferably about 550°C.

[0043] According to one aspect of the invention, the system includes a plurality of heat exchangers upstream of the pre-cracking reactor, which are arranged to preheat the ammonia feed stream before it enters the pre-cracking reactor.

[0044] The term "adiabatic reactor" is used to refer to a chemical reactor in which the temperature decreases from the reactor inlet to the outlet, particularly a single-volume chemical reactor.

[0045] In one aspect of the invention, a cracking catalyst bed is arranged to produce outflow gas from a partially converted ammonia feed stream at a temperature between 500°C and 900°C, preferably between 600°C and 800°C, for example at a pressure of about 30 barg.

[0046] In one aspect of the invention, a pre-cracked catalyst bed is arranged to produce a partially converted ammonia feed stream comprising ammonia, hydrogen, and nitrogen at a temperature between 350°C and 650°C, preferably about 550°C, for example at a pressure of about 30 barg.

[0047] According to one aspect of the invention, the ammonia cracking reactor is a flame-heated reactor comprising one or more catalyst-filled tubes, the tubes being at least partially filled with a cracking catalyst bed.

[0048] According to one aspect of the invention, the system includes a combustion chamber in which fuel gas is burned to heat an ammonia cracking reactor.

[0049] According to one aspect of the invention, the system includes a fuel gas flow circulation conduit arranged to conduct the fuel gas flow from a fuel gas source to a combustion chamber.

[0050] According to one aspect of the invention, the pre-cracking reactor, particularly the adiabatic pre-cracking reactor, is a single-vessel reactor at least partially filled with a pre-cracked catalyst bed.

[0051] Single-vessel reactors have a simple geometry and therefore experience less thermal expansion than catalyst-packed tubes. Consequently, catalyst beds filling such single-vessel reactors experience less mechanical stress than catalyst beds filling catalyst-packed tubes. The inventors have discovered that the increased porosity of the pre-cracked catalyst pellets is compatible with this lower mechanical stress.

[0052] According to one aspect of the invention, the length of the pre-cracking reactor between its inlet and outlet is 3 m to 6 m.

[0053] According to one aspect of the invention, each tube has a length of approximately 12 m.

[0054] According to one aspect of the invention, a single-container pre-cracking reactor includes a first pre-cracking catalyst bed and a second pre-cracking catalyst bed, the second pre-cracking catalyst bed being downstream of the first pre-cracking catalyst bed in the direction of ammonia feed flow, the first and second pre-cracking catalyst beds being arranged to carry out an endothermic cracking reaction of ammonia, and the activation temperature of the first pre-cracking catalyst bed being different from the activation temperature of the second pre-cracking catalyst bed.

[0055] According to one aspect of the invention, at least one tube of an ammonia cracking reactor includes a first cracking catalyst bed and a second cracking catalyst bed, the second cracking catalyst bed being downstream of the first cracking catalyst bed in the direction of ammonia feed flow, the first and second cracking catalyst beds being arranged to carry out an endothermic cracking reaction of ammonia, and the activation temperature of the first cracking catalyst bed being different from the activation temperature of the second cracking catalyst bed.

[0056] According to one aspect of the invention, the system includes a hydrogen recovery unit arranged for producing hydrogen products from the outflowing gas stream.

[0057] According to one aspect of the invention, the ammonia feed stream contains impurities such as sulfur, oil, chlorine, and water at ppm levels. In other words, the ammonia feed stream has a high purity level and does not cause impurity deposition on the pre-cracking and cracking catalyst beds.

[0058] This invention also relates to a method for producing hydrogen from ammonia, comprising the following steps:

[0059] - Provide ammonia feed flow;

[0060] - The ammonia feed stream is fed to at least one ammonia pre-cracking reactor to produce a partially converted ammonia feed stream containing ammonia, hydrogen, and nitrogen through a pre-cracking reaction. The pre-cracking reactor contains a pre-cracking catalyst bed containing 20 to 60 wt% nickel, preferably 25 to 50 wt% nickel, as the pre-cracking catalytic active material.

[0061] - The partially converted ammonia feed stream is fed to an ammonia cracking reactor to produce an effluent gas stream containing hydrogen and nitrogen, and optionally unconverted ammonia, through a cracking reaction. The cracking reactor contains a cracking catalyst bed containing 10% to 20% by weight of nickel as a cracking catalytic active material.

[0062] According to one aspect of the invention, the method includes feeding the outflowing gas stream to a hydrogen recovery unit to generate the hydrogen product and an exhaust stream comprising hydrogen, nitrogen, and optionally unconverted ammonia.

[0063] The pre-cracking reaction is a reaction in which the feedstock (in this case, the ammonia feed stream) is pre-cracking upstream of the cracking reaction.

[0064] According to one aspect of the invention, the step of feeding the ammonia feed stream to the pre-cracking reactor is carried out in an adiabatic pre-cracking reactor.

[0065] According to one aspect of the invention, the method includes the step of preheating the ammonia feed stream upstream of the pre-cracking reactor. In other words, the ammonia feed stream is preheated before the pre-cracking reaction.

[0066] According to one aspect of the invention, preheating is carried out in a heat exchanger (also called a preheater) upstream of the pre-cracking reactor in the direction of the ammonia feed flow.

[0067] According to one aspect of the invention, the ammonia feed stream is preheated at a temperature between 350°C and 650°C, preferably at a temperature of about 550°C.

[0068] According to one aspect of the invention, the preheating step is not carried out in the pre-cracking reactor.

[0069] In one aspect of the invention, the pre-cracking reaction is carried out at a conversion rate lower than that of the cracking reaction.

[0070] According to one aspect of the invention, the catalytic conversion rate of the pre-cracking reaction is between 10% and 90%, preferably between 15% and 50%, and more preferably between 15% and 35%.

[0071] In one aspect of the invention, the pre-cracking reaction is carried out at a lower temperature than the cracking reaction.

[0072] In one aspect of the invention, the pre-cracking reaction is carried out at a temperature between 350°C and 650°C, preferably about 550°C, for example at a pressure of about 30 barg.

[0073] In one aspect of the invention, the cracking reaction is carried out at a temperature between 500°C and 900°C, preferably between 600°C and 800°C, for example at a pressure of about 30 barg.

[0074] According to one aspect of the invention, the pre-cracking reaction is carried out in a pre-cracking catalyst bed. Specifically, the pre-cracking catalyst bed comprises a pre-cracking support, on which the pre-cracking catalytically active material is placed. The pre-cracking support comprises, for example, materials selected from MgO or CaO (Al₂O₃). n Materials that are either MgAl2O4, AL2O3, or ZrO2.

[0075] According to one aspect of the invention, the pre-cracking reaction is carried out in a pre-cracking catalyst bed comprising a plurality of pre-cracking catalyst particles, the pre-cracking catalyst particles comprising a pre-cracking support and a pre-cracking catalytic active material on the pre-cracking support.

[0076] According to one aspect of the invention, the cracking reaction is carried out in a cracking catalyst bed. Specifically, the cracking catalyst bed comprises a cracking support on which the catalytically active cracking material is placed. The cracking support comprises, for example, a material selected from Al₂O₃, particularly α-Al₂O₃, CalAl₂O₄, particularly α-CalAl₂O₄, or K / CaAl₂O₄, or α-K / CaAl₂O₄, or CaK₂Al₂O₃⁴, or MgAl₂O₄.

[0077] According to one aspect of the invention, the cracking reaction is carried out in a cracking catalyst bed comprising a plurality of cracking catalyst particles, said cracking catalyst particles comprising a cracking support and a cracking catalytically active material on the cracking support.

[0078] According to one aspect of the invention, the pre-cracking catalyst pellets and the cracking catalyst pellets have a metal surface area, wherein the metal surface area of ​​the pre-cracking catalyst pellets is higher than that of the cracking catalyst pellets. Specifically, the metal surface area of ​​the pre-cracking catalyst pellets is 50% or 25% higher than that of the cracking catalyst pellets.

[0079] According to one aspect of the invention, the metal surface area of ​​the pre-cracked catalyst particles is 10 m². 2 .g -1 up to 35 m 2 .g -1 between.

[0080] According to one aspect of the invention, the metal surface area of ​​the cracking catalyst particles is 2 m². 2 .g -1 Up to 4 m 2 .g -1 between.

[0081] According to one aspect of the invention, the nickel dispersion in the pre-cracked catalyst pellets is between 3% and 9%.

[0082] According to one aspect of the invention, the nickel dispersion in the cracking catalyst pellets is between 3% and 6%.

[0083] According to one aspect of the invention, the average nickel crystallite size in the pre-cracked catalyst particles is between 10 nm and 30 nm.

[0084] According to one aspect of the invention, the average nickel crystallite size in the cracking catalyst pellets is between 15 nm and 40 nm.

[0085] According to one aspect of the invention, the metal surface area of ​​the precracked catalyst pellets, the nickel dispersion in the precracked catalyst pellets, and / or the average nickel crystallite size in the precracked catalyst pellets are measured by hydrogen chemisorption analysis, wherein the metal surface area, nickel dispersion, and / or average nickel crystallite size are determined by hydrogen adsorption isotherms, particularly according to the ASTM D3908-20 standard procedure.

[0086] According to one aspect of the invention, the metal surface area of ​​the cracking catalyst pellets, the nickel dispersion in the cracking catalyst pellets, and / or the average nickel crystallite size in the cracking catalyst pellets are measured by hydrogen chemisorption analysis, wherein the metal surface area, nickel dispersion, and / or average nickel crystallite size are determined by hydrogen adsorption isotherms, particularly according to the ASTM D3908-20 standard procedure.

[0087] Specifically, prior to hydrogen chemisorption measurements, the pre-cracked catalyst or cracked catalyst is degassed under vacuum at a temperature rate of 1°C to 10°C / min at a temperature between 150 and 250°C, and then held in this state for 1 to 2 hours.

[0088] Then, the degassed pre-cracking catalyst is reduced at a temperature rate of 1°C to 10°C / min by passing pure hydrogen gas through it, between 350°C and 450°C, or the degassed cracking catalyst is reduced at a temperature rate of 450°C to 600°C. The pre-cracking catalyst or cracking catalyst is then held in this state for 1 to 2 hours.

[0089] The pre-cracked catalyst or cracked catalyst is then evacuated under vacuum for 1 to 2 hours at a temperature similar to that of reduction to remove the adsorbed hydrogen from the surface.

[0090] The pre-cracked catalyst or cracked catalyst is then cooled to 40°C to reach the temperature used for hydrogen chemisorption measurements.

[0091] Then, hydrogen was incrementally titrated onto the catalyst at 40°C, and the pressure was recorded after each pressure increase, allowing sufficient time to reach equilibrium.

[0092] Specifically, the ASTM D3908-20 standard is used for calibration.

[0093] According to one aspect of the invention, the porosity of the pre-cracked catalyst pellets is higher than that of the cracked catalyst pellets.

[0094] According to one aspect of the invention, the specific surface area of ​​the pre-cracked catalyst particles is higher than that of the cracked catalyst particles.

[0095] Metallic surface area refers to the surface of the granules in contact with reactants (e.g., ammonia). The porosity of the granules of this invention enables an increased active surface area and thus improved reaction efficiency.

[0096] According to one aspect of the invention, the pre-cracking catalyst pellets and the cracking catalyst pellets have a shape selected from spherical or cylindrical.

[0097] According to one aspect of the invention, the cracking catalyst pellet shape includes at least one pore penetrating each of the pellets.

[0098] According to one aspect of the invention, the cracking catalyst pellets have a cylindrical shape with a rounded tip and / or a corrugated cylindrical shape.

[0099] These shapes of cracking catalyst pellets are advantageous in ammonia cracking reactors, where there is more pressure drop limitation than in pre-cracking reactors.

[0100] According to one aspect of the invention, the pre-cracked catalyst pellet shape does not include pores penetrating each of the pellets.

[0101] The shapes of the pre-cracked pellets and cracked pellets of the present invention increase the heat exchange between the catalyst and ammonia, and are selected based on the typical pressure drops occurring in the pre-cracked reactor and ammonia cracking reactor, respectively. This results in an improved reaction.

[0102] According to one aspect of the invention, each cracking catalyst pellet has a cylindrical shape with a diameter of 8 mm to 20 mm and a length of 8 mm to 20 mm.

[0103] According to one aspect of the invention, each pre-cracked catalyst pellet has a cylindrical shape with a diameter of 3 mm to 6 mm and a length of 3 mm to 6 mm.

[0104] According to one aspect of the invention, the method includes the step of heating a cracking reactor, the heating step comprising burning a fuel gas stream in a combustion reaction carried out in a combustion chamber, thereby generating the heat.

[0105] According to one aspect of the invention, fuel gas is supplied to the combustion chamber via a fuel gas flow circulation pipe.

[0106] According to one aspect of the invention, the method includes the step of conveying a first portion of ammonia partially converted from a pre-cracking reaction to a combustion chamber.

[0107] According to one aspect of the invention, the ammonia feed stream circulates in a single direction in the pre-cracking reactor.

[0108] According to one aspect of the invention, the generation of byproduct vapors in the hydrogen product production process is reduced compared to SMR reactions. Preferably, the generation of byproduct vapors during the pre-cracking and cracking reaction processes is avoided.

[0109] The present invention also relates to the use of a system for cracking ammonia to produce hydrogen products, said system comprising:

[0110] - At least one pre-cracking reactor arranged to receive an ammonia feed stream to produce a partially converted ammonia feed stream comprising ammonia, hydrogen, and nitrogen, said at least one pre-cracking reactor comprising a pre-cracking catalyst bed containing 20% ​​to 60% by weight nickel, preferably 25% to 50% by weight nickel as the pre-cracking catalytic active material.

[0111] - At least one ammonia cracking reactor arranged to receive the partially converted ammonia feed stream to produce an effluent gas stream comprising hydrogen and nitrogen and optionally unconverted ammonia, the ammonia cracking reactor comprising a cracking catalyst bed comprising 10% to 20% by weight of nickel as a cracking catalytic active material.

[0112] Other features, details, and advantages of the invention will become more apparent from the following description given as an indication, with reference to the accompanying drawings, in which:

[0113] [ Figure 1 [Illustration] is a schematic diagram of the system according to the present invention.

[0114] [ Figure 2 [Illustration] is a schematic diagram of the method according to the present invention.

[0115] First, it should be noted that the accompanying drawings disclose the invention in detail for the purpose of carrying out the invention, and the drawings can of course be used to more clearly define the invention when necessary.

[0116] Figure 1 This is a schematic diagram of the system of the present invention for producing hydrogen from ammonia. System 1 includes:

[0117] - A pre-cracking reactor 3, arranged to produce a partially converted ammonia feed stream 101 containing ammonia, hydrogen, and nitrogen from an ammonia feed stream 100 from an ammonia source 2, the pre-cracking reactor 3 comprising a pre-cracking catalyst bed 13, the pre-cracking catalyst bed 13 comprising 20% ​​to 60% by weight nickel, preferably 25% to 50% by weight nickel as the pre-cracking catalytic active material.

[0118] - An ammonia cracking reactor 4, arranged to receive the partially converted ammonia feed stream 101 to produce an effluent gas stream 102 comprising hydrogen and nitrogen and optionally unconverted ammonia, the ammonia cracking reactor 4 comprising a cracking catalyst bed 14 comprising 10% to 20% by weight nickel as a cracking catalytic active material.

[0119] Nickel exhibits high catalytic activity, leading to high conversion rates with selected compositions. Furthermore, nickel demonstrates good kinetics at a reasonable cost.

[0120] The pre-cracking 13 and cracking 14 catalyst beds have the specific features disclosed below.

[0121] The pre-cracked catalyst bed 13 includes a pre-cracked support, wherein the pre-cracked catalytic active material is disposed on the pre-cracked support, and the pre-cracked support comprises materials selected from MgO and CaO (Al2O3). nMaterials consisting of MgAl2O4, Al2O3, and ZrO2. The pre-cracked catalyst bed comprises multiple pre-cracked catalyst particles, which are contained in the pre-cracked catalytic active material on the pre-cracked support.

[0122] The cracking catalyst bed 14 comprises a cracking support on which the cracking catalytically active material is placed. The cracking support comprises a material selected from Al₂O₃, particularly α-Al₂O₃; CalAl₂O₄, particularly α-CalAl₂O₄; K / CaAl₂O₄; α-K / CaAl₂O₄; CaK₂Al₂O₃; and MgAl₂O₄. The cracking catalyst bed comprises a plurality of cracking catalyst particles, which are contained within the cracking catalytically active material on the cracking support.

[0123] These selected supports for the cracking catalyst bed and the pre-cracking catalyst bed improved the stability of the catalyst beds 13 and 14, and thereby improved the reaction efficiency.

[0124] The metal surface area of ​​the pre-cracking catalyst pellets is higher than that of the cracking catalyst pellets. Specifically, the metal surface area of ​​the pre-cracking catalyst pellets is 50% or 25% higher than that of the cracking catalyst pellets. For example, the metal surface area of ​​the pre-cracking catalyst pellets is 10 μm². 2 .g -1 up to 35 m 2 .g -1 Between, and the metal surface area of ​​the cracking catalyst particles is 2 m² 2 .g -1 Up to 4 m 2 .g -1 between.

[0125] Here, the nickel dispersion in the pre-cracked catalyst pellets is between 3% and 9%, and the nickel dispersion in the cracked catalyst pellets is between 3% and 6%.

[0126] In this embodiment, the average nickel crystallite size in the pre-cracked catalyst particles is between 10 nm and 30 nm, and the average nickel crystallite size in the cracked catalyst particles is between 15 nm and 40 nm.

[0127] In this embodiment, the metal surface area of ​​the precracked catalyst pellets, the nickel dispersion in the precracked catalyst pellets, and / or the average nickel crystallite size in the precracked catalyst pellets are measured by hydrogen chemisorption analysis. The metal surface area, nickel dispersion, and / or average nickel crystallite size are determined by hydrogen adsorption isotherms, specifically according to the ASTM D3908-20 standard procedure.

[0128] The porosity of pre-cracked catalyst particles is higher than that of cracked catalyst particles, and the specific surface area of ​​pre-cracked catalyst particles is higher than that of cracked catalyst particles.

[0129] The specific characteristics of the pre-cracking and cracking catalyst particles (metal surface area, nickel dispersion, nickel crystallite size, porosity, specific surface area) lead to improved catalyst efficiency and thus better conversion rates in pre-cracking reactor 3 and cracking reactor 4.

[0130] The pre-cracking catalyst pellets and the cracking catalyst pellets have shapes selected from spherical or cylindrical. The cracking catalyst pellets may have a shape including at least one pore penetrating each pellet and / or may have a cylindrical shape with rounded apexes and / or a corrugated cylindrical shape. These shapes of the cracking catalyst pellets are advantageous in ammonia cracking reactors, where there is more pressure drop limitation than in pre-cracking reactors. For example, the pre-cracking pellet shape does not include a pore penetrating each pellet. The shapes of the pre-cracking pellets and cracking pellets of the present invention increase the heat exchange between the catalyst and ammonia and are selected based on the typical pressure drops occurring in the pre-cracking reactor 3 and the cracking reactor 4, respectively.

[0131] The pre-cracking reactor 3 is an adiabatic pre-cracking reactor. System 1 includes at least one heat exchanger 5 upstream of the pre-cracking reactor 3, which is arranged to preheat the ammonia feed stream 100 at a temperature between 350°C and 650°C, preferably about 550°C, before it enters the pre-cracking reactor 3. Such a heat exchanger is also called a preheater.

[0132] In one embodiment not shown here, system 1 includes a plurality of heat exchangers upstream of the pre-cracking reactor, which are arranged to preheat the ammonia feed stream before it enters the pre-cracking reactor.

[0133] The cracking catalyst bed 14 is arranged to produce outflow gas 102 from a partially converted ammonia feed stream at a temperature between 500°C and 900°C, preferably between 600°C and 800°C, for example at a pressure of about 30 barg.

[0134] The pre-cracked catalyst bed 13 is arranged to produce a partially converted ammonia feed stream 101 containing ammonia, hydrogen and nitrogen at a temperature between 350°C and 650°C, preferably about 550°C, for example at a pressure of about 30 barg.

[0135] The ammonia cracking reactor 4 is a flame-heated reactor comprising one or more catalyst-filled tubes, which are at least partially filled with a cracking catalyst bed 14. Each tube has a length of approximately 12 m.

[0136] System 1 includes a combustion chamber 8 in which fuel gases are burned to heat the cracking reactor 4. System 1 therefore includes a fuel gas feed recirculation conduit 10 arranged to conduct a fuel gas feed stream 104 from a fuel gas source 9 to the combustion chamber 9. In one embodiment, not shown here, the fuel gas source is an ammonia feed stream 100.

[0137] System 1 includes a partially converted ammonia feed stream circulation pipe 6, which is arranged to conduct a first portion of the partially converted ammonia feed stream from the pre-cracking reactor 3 to the fuel gas feed stream circulation pipe 10 or to the combustion chamber 8, and to conduct a second portion of the partially converted ammonia feed stream to the cracking reactor 4.

[0138] The cracking reactor 4 is heated by the heat h generated from the first portion of the ammonia feed stream, which is partially converted during the combustion reaction in the combustion chamber. The pre-cracking reactor 3, particularly the adiabatic pre-cracking reactor, is a single-vessel reactor at least partially filled with a pre-cracking catalyst bed 13. The length of the pre-cracking reactor 13 between its inlet and outlet is 3 m to 6 m.

[0139] System 1 includes a hydrogen recovery unit 11, which is arranged to produce hydrogen product 103 from the outflowing gas stream 102. Figure 2 This is a schematic diagram of the method for producing hydrogen from ammonia according to the present invention. Method 200 includes the following steps:

[0140] The present invention also relates to a method 200 for producing hydrogen from ammonia, comprising the following steps:

[0141] - Provides 100g of 201 ammonia feed;

[0142] - The ammonia feed stream 100 is fed to at least one ammonia pre-cracking reactor 203 to produce a partially converted ammonia feed stream 101 containing ammonia, hydrogen, and nitrogen through a pre-cracking reaction. The pre-cracking reactor includes a pre-cracking catalyst bed containing 20% ​​to 60% by weight nickel, preferably 25% to 50% by weight nickel, as the pre-cracking catalytic active material.

[0143] - The partially converted ammonia feed stream 101 is fed to an ammonia cracking reactor 204 to produce an effluent gas stream 102 containing hydrogen and nitrogen and optionally unconverted ammonia through a cracking reaction. The cracking reactor contains a cracking catalyst bed containing 10% to 20% by weight of nickel as a cracking catalytic active material.

[0144] - The outflowing gas stream 102 is sent to the hydrogen recovery unit 205 to produce the hydrogen product 103 and an exhaust stream containing hydrogen, nitrogen and optionally unconverted ammonia.

[0145] Step 203, which involves feeding the ammonia feed stream to the pre-cracking reactor, is carried out in an adiabatic pre-cracking reactor. In other words, the heat supplied to the pre-cracking reactor is negligible, and therefore the temperature decreases from the inlet to the outlet of the pre-cracking reactor.

[0146] The method includes a step of preheating the ammonia feed stream 100 upstream of the step of feeding the ammonia feed stream to the pre-cracking reactor 203. In other words, the ammonia feed stream is preheated before the pre-cracking reaction. The preheating step 202 is carried out in a heat exchanger (also called a preheater) upstream of the pre-cracking reactor in the direction of the ammonia feed stream 100. The ammonia feed stream 100 is preheated at a temperature between 350°C and 650°C, preferably at a temperature of about 550°C. The preheating step 202 is not carried out in the pre-cracking reactor, but before the step of feeding to the pre-cracking reactor and therefore before the pre-cracking reaction.

[0147] The pre-cracking reaction is carried out at a lower temperature than the cracking reaction.

[0148] The pre-cracking reaction is carried out at a temperature between 350°C and 650°C, preferably about 550°C, for example at a pressure of about 30 barg. The cracking reaction is carried out at a temperature between 500°C and 900°C, preferably between 600°C and 800°C, for example at a pressure of about 30 barg.

[0149] The pre-cracking reaction is carried out in a pre-cracking catalyst bed as previously disclosed. The cracking reaction is carried out in a cracking catalyst bed as previously disclosed.

[0150] Method 200 includes a step 209 of heating the cracking reactor, said heating step 209 comprising burning the fuel gas stream 104 into a flue gas stream in a combustion reaction taking place in the combustion chamber. Fuel gas is supplied to the combustion chamber through a fuel gas stream circulation pipe.

[0151] The method includes step 208 of conveying a first portion of ammonia 101, partially converted from the pre-cracking reaction, to the combustion chamber.

[0152] The ammonia feed stream circulates in a single direction within the pre-cracking reactor.

[0153] The method includes a step 206 of processing hydrogen products, such as a step of purifying hydrogen products.

Claims

1. A method (200) for producing hydrogen from ammonia, comprising the following steps: - Provide ammonia feed flow (201); - The ammonia feed stream is fed to at least one ammonia pre-cracking reactor to produce a partially converted ammonia feed stream containing ammonia, hydrogen, and nitrogen through a pre-cracking reaction (203). The pre-cracking reactor contains a pre-cracking catalyst bed containing 20% ​​to 60% by weight nickel, preferably 25% to 50% by weight nickel, as the pre-cracking catalytic active material. - The partially converted ammonia feed stream is fed to an ammonia cracking reactor to produce an effluent gas stream containing hydrogen and nitrogen and optionally unconverted ammonia by a cracking reaction (204), the cracking reactor containing a cracking catalyst bed containing 10% to 20% by weight of nickel as a cracking catalytic active material.

2. The method (200) according to claim 1, wherein the pre-cracking reaction (203) is carried out in the pre-cracking catalyst bed, the pre-cracking catalyst bed comprising a pre-cracking support, the pre-cracking catalytically active material on the pre-cracking support, and the cracking reaction (204) is carried out in the cracking catalyst bed, the cracking catalyst bed comprising a cracking support, the cracking catalytically active material on the cracking support.

3. The method according to the preceding claim, wherein the pre-cracking support comprises a material selected from MgO, or CaO(Al2O3)n, or MgAl2O4, or Al2O3, or ZrO2, and the cracking support comprises a material selected from Al2O3, particularly α-Al2O3, CalAl2O4, particularly α-CalAl2O4, or K / CaAl2O4, or α-K / CaAl2O4, or CaK2Al22O34, or MgAl2O4.

4. The method (200) according to any one of claims 2 or 3, wherein the pre-cracking reaction (203) is carried out in a pre-cracking catalyst bed comprising a plurality of pre-cracking catalyst particles, the pre-cracking catalyst particles comprising a pre-cracking support and a pre-cracking catalytic active material on the pre-cracking support, and the cracking reaction (204) is carried out in a cracking catalyst bed comprising a plurality of cracking catalyst particles, the cracking catalyst particles comprising a cracking support and a cracking catalytic active material on the cracking support.

5. The method (200) according to claim 4, wherein the pre-cracked catalyst pellets and the cracked catalyst pellets have metal surface areas, and the metal surface area of ​​the pre-cracked catalyst pellets is higher than that of the cracked catalyst pellets.

6. The method (200) according to claim 4 or 5, wherein the nickel dispersion in the pre-cracked catalyst pellets is between 3% and 9%, and the nickel dispersion in the cracked catalyst pellets is between 3% and 6%.

7. The method (200) according to any one of claims 4 to 6, wherein the average nickel crystallite size in the pre-cracked catalyst particles is between 10 nm and 30 nm, and the average nickel crystallite size in the cracked catalyst particles is between 15 nm and 40 nm.

8. The method (200) according to any one of claims 4 to 7, wherein the porosity of the pre-cracked catalyst particles is higher than that of the cracked catalyst particles.

9. The method (200) according to any one of claims 4 to 8, wherein the specific surface area of ​​the pre-cracked catalyst particles is higher than that of the cracked catalyst particles.

10. The method (200) according to any one of claims 4 to 9, wherein the cracking catalyst pellets are cylindrical and have a cylindrical shape with a rounded top and / or a corrugated cylindrical shape.

11. The method (200) according to any one of claims 4 to 10, wherein the cracking catalyst pellet shape comprises at least one pore penetrating each of the pellets.

12. A system (1) for producing hydrogen products from ammonia, comprising: - At least one pre-cracking reactor (3) arranged to receive an ammonia feed stream to produce a partially converted ammonia feed stream comprising ammonia, hydrogen, and nitrogen, said at least one pre-cracking reactor (3) comprising a pre-cracking catalyst bed (13) comprising 20% ​​to 60% by weight nickel, preferably 25% to 50% by weight nickel as the pre-cracking catalytic active material. - At least one ammonia cracking reactor (4) arranged to receive the partially converted ammonia feed stream to produce an effluent gas stream comprising hydrogen and nitrogen and optionally unconverted ammonia, the ammonia cracking reactor (4) comprising a cracking catalyst bed (14) comprising 10% to 20% by weight of nickel as a cracking catalytic active material.

13. The system (1) according to claim 12, wherein the pre-cracked catalyst bed (13) comprises a pre-cracked support, the pre-cracked catalytic active material is on the pre-cracked support, and wherein the cracking catalyst bed (14) comprises a cracking support, the cracking catalytic active material is on the cracking support.

14. The system (1) according to claim 13, wherein the precracked catalyst bed (13) comprises a plurality of precracked catalyst particles, which comprises a precracked support and a precracked catalytic active material on the precracked support, and the cracked catalyst bed (14) comprises a plurality of cracked catalyst particles, which comprises a cracked support and a cracked catalytic active material on the cracked support.

15. The system (1) according to claim 14, wherein the metal surface area of ​​the pre-cracked catalyst particles is higher than the metal surface area of ​​the cracked catalyst particles.

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