Method for synthesizing ammonia through electro-thermal catalysis

Abstract

The invention relates to the technical field of catalysis, in particular to a method for synthesizing ammonia through electro-thermal catalysis. The method comprises the following steps: contacting nitrogen, hydrogen and a catalyst in a power-on state, and reacting to obtain ammonia gas; wherein the catalyst comprises an active component and a catalyst carrier; the active component comprises a transition metal, and the transition metal comprises one of ruthenium, iron, cobalt or nickel; the catalyst carrier comprises a first rare earth hydride ReHx or a rare earth oxygen hydride ReH3-2yOy; wherein Re is a rare earth element; 2 < = x < = 3; 0 lt; y < = 1. According to the method, efficient ammonia synthesis under mild conditions is realized by applying an external electric field, screening an electrothermal catalyst and reasonably designing process parameters, and the method has the advantages of mild reaction conditions, high synthesis efficiency, low energy consumption, strong operational feasibility and the like.

Description

Technical Field

[0001] The invention relates to the field of catalytic technology, and in particular to a method for synthesizing ammonia by electrothermal catalysis. Background Art

[0002] Ammonia has the advantages of easy liquefaction, high energy density, large hydrogen storage capacity, mature production, storage and transportation technology, and no carbon-containing compounds produced when decomposed. It can be used as a raw material for fertilizers, plastics, medicines and synthetic fibers, and can also be used as a hydrogen carrier with potential application prospects.

[0003] The Haber-Bosch process is mainly used for industrial ammonia synthesis, which converts nitrogen and hydrogen into ammonia over transition metals. Due to thermodynamic and kinetic limitations, the process needs to be carried out under high temperature (350-500°C) and high pressure (10-30MPa), resulting in high energy consumption. The energy consumed by the process each year accounts for 1-2% of the world's total energy supply, and carbon dioxide emissions account for 1.5% of the global total emissions. At present, two generations of industrial ammonia synthesis catalysts, iron-based and ruthenium-based, have been developed. Although iron-based catalysts are low-cost, they require high temperature and high pressure conditions to achieve a high ammonia synthesis efficiency. Ruthenium-based catalysts have the advantages of high activity and relatively mild reaction conditions, but they are expensive and their reaction activity under low temperature conditions still needs to be improved. Therefore, there is an urgent need to find a new technology that can efficiently synthesize ammonia under mild conditions.

[0004] Compared with the traditional Haber-Bosch process, electrocatalysis and plasma catalysis technology can utilize the synergistic effect between electrochemical and catalytic processes, and thus are expected to achieve efficient synthesis of ammonia under low temperature conditions. Electrocatalytic synthesis of ammonia is the cathode reduction of nitrogen molecules on metal electrodes. This method has the advantage of mild reaction conditions, but the low solubility of nitrogen severely limits its mass transfer process. In addition, due to the competition of other side reactions, it is difficult to improve the Faraday efficiency of synthetic ammonia and the ammonia yield is low, which seriously restricts its industrial development. Plasma catalytic synthesis of ammonia uses high-energy electrons to excite the vibrational state of nitrogen molecules in the gas phase and adsorb them on the catalyst, effectively improving the efficiency of ammonia synthesis. However, the energy required to excite and manufacture plasma in this process is high, the process energy consumption is large, and a special plasma generator is required. The equipment manufacturing and operation costs are high, which limits its promotion in large-scale industrial applications. Therefore, it is of great research significance to develop new and efficient synthesis of ammonia technology under mild conditions. Summary of the invention

[0005] The present invention aims to solve at least one of the technical problems in the related art to a certain extent. To this end, the present invention provides a method for synthesizing ammonia by electrothermal catalysis, which realizes efficient ammonia synthesis under mild conditions by applying an external electric field, screening electrothermal catalysts and rationally designing process parameters. The method has the advantages of mild reaction conditions, high synthesis efficiency, low energy consumption, strong operational feasibility, etc.

[0006] To this end, the first aspect of the present invention provides a method for synthesizing ammonia by electrothermal catalysis, comprising the following steps:

[0007] Nitrogen and hydrogen are brought into contact with a catalyst under an electric state to react and obtain ammonia;

[0008] Wherein, the catalyst comprises an active component and a catalyst carrier;

[0009] The active component includes a transition metal, and the transition metal includes one of ruthenium, iron, cobalt or nickel;

[0010] The catalyst support includes a first rare earth hydride ReH x Or rare earth oxyhydride ReH 3-2y O y ;

[0011] Wherein, Re is a rare earth element; 2≤x≤3; 0 <y≤1。

[0012] The present invention directly applies an electric field to the traditional catalyst bed. By applying an external electric field, the electronic structure of the catalyst and reactants can be changed, and the electron transfer on the catalyst surface can be accelerated, thereby promoting the catalytic reaction. By adjusting the external electric field, the adsorption behavior and kinetic parameters of the reactants and intermediates can also be changed, affecting the breaking and formation of chemical bonds on the catalyst surface, thereby realizing the manipulation of the reaction path. In addition, the present invention can achieve efficient ammonia synthesis under mild conditions by screening electrothermal catalysts and rationally designing process parameters. Compared with traditional thermal catalysis, electrocatalysis and plasma catalysis, this method has the advantages of mild reaction conditions, high synthesis efficiency, low energy consumption, and strong operational feasibility.

[0013] According to an embodiment of the present invention, the content of the active component is 0.1%-20% of the total mass of the catalyst.

[0014] According to an embodiment of the present invention, the volume ratio of nitrogen to hydrogen is (1-9):(9-1).

[0015] According to an embodiment of the present invention, the reaction temperature is 50°C-500°C.

[0016] According to an embodiment of the present invention, the reaction pressure is 0.1 MPa-30 MPa.

[0017] According to an embodiment of the present invention, the space velocity of the nitrogen and hydrogen is 1000 mL·g· cat -1 ·h -1 -1000000mL·g· cat -1 ·h -1 .

[0018] According to an embodiment of the present invention, the voltage used in the reaction is 0-60V, the current is 0-10A, and both the voltage and the current are not zero.

[0019] According to an embodiment of the present invention, the method further comprises the following steps of preparing the first rare earth hydride:

[0020] Carrying out a hydrogenation reaction on a rare earth hydride precursor to obtain the first rare earth hydride;

[0021] Wherein, the rare earth hydride precursor includes at least one of scandium, yttrium, lanthanum, praseodymium, neodymium, promethium, samarium, europium, and gadolinium;

[0022] According to an embodiment of the present invention, the temperature of the hydrogenation reaction is 30°C-800°C.

[0023] According to an embodiment of the present invention, the pressure of the hydrogenation reaction is 0.5 MPa-5 MPa.

[0024] According to an embodiment of the present invention, the hydrogenation reaction time is 2h-12h.

[0025] According to an embodiment of the present invention, the method further comprises the following steps of preparing the rare earth oxyhydride:

[0026] The rare earth oxide is once calcined in an inert atmosphere;

[0027] A second rare earth hydride is added and calcined twice in hydrogen to obtain the rare earth oxyhydride.

[0028] According to an embodiment of the present invention, the rare earth oxide includes at least one of scandium oxide, yttrium oxide, lanthanum oxide, praseodymium oxide, neodymium oxide, promethium oxide, samarium oxide, europium oxide, and gadolinium oxide.

[0029] According to an embodiment of the present invention, the second rare earth hydride includes at least one of scandium hydride, yttrium hydride, lanthanum hydride, praseodymium hydride, neodymium hydride, promethium hydride, samarium hydride, europium hydride, and gadolinium hydride.

[0030] According to an embodiment of the present invention, the molar ratio of the second rare earth hydride to the rare earth oxide is (1-30):1.

[0031] According to an embodiment of the present invention, the temperature of the primary calcination is 200°C-1200°C.

[0032] According to an embodiment of the present invention, the time of the first calcination is 1h-20h.

[0033] According to an embodiment of the present invention, the temperature of the secondary calcination is 400°C-1000°C.

[0034] According to an embodiment of the present invention, the secondary calcination time is 10h-24h.

[0035] According to an embodiment of the present invention, the pressure of the secondary calcination is 0.1 MPa-2 MPa.

[0036] According to an embodiment of the present invention, the method further comprises the following steps of preparing the catalyst:

[0037] Adding a transition metal precursor into a solvent, adding the catalyst support for impregnation, drying, and reducing with hydrogen to obtain the catalyst;

[0038] Wherein, the transition metal precursor is used to provide the active component.

[0039] According to an embodiment of the present invention, the transition metal precursor includes at least one of chloride, nitrate, acetylacetonate, and carbonyl complex.

[0040] According to an embodiment of the present invention, the chloride includes at least one of ruthenium trichloride, ferric chloride, cobalt chloride and nickel chloride.

[0041] According to an embodiment of the present invention, the nitrate includes at least one of ruthenium nitrosyl nitrate, iron nitrate, cobalt nitrate and nickel nitrate.

[0042] According to an embodiment of the present invention, the acetylacetonate includes at least one of ruthenium acetylacetonate, iron acetylacetonate, cobalt acetylacetonate, and nickel acetylacetonate.

[0043] According to an embodiment of the present invention, the carbonyl complex includes at least one of triruthenium dodecacarbonyl, diiron nonacarbonyl, dicobalt octacarbonyl, and nickel tetracarbonyl.

[0044] According to an embodiment of the present invention, the immersion temperature is 20°C-100°C.

[0045] According to an embodiment of the present invention, the immersion time is 0.3h-12h.

[0046] According to an embodiment of the present invention, the solvent includes at least one of methanol, ethanol or tetrahydrofuran.

[0047] According to an embodiment of the present invention, the drying temperature is 60°C-120°C.

[0048] According to an embodiment of the present invention, the drying time is 0.5h-12h.

[0049] According to an embodiment of the present invention, the temperature of the hydrogen reduction is 200°C-600°C.

[0050] According to an embodiment of the present invention, the time of hydrogen reduction is 1h-12h.

[0051] According to an embodiment of the present invention, the hydrogen flow rate in the hydrogen reduction is 30 mL min -1 -100mL·min -1 .

[0052] The beneficial effects of the present invention compared to the prior art are as follows:

[0053] The present invention successfully achieves efficient ammonia synthesis under mild conditions by applying an external electric field, simultaneously screening electrothermal catalysts, and rationally designing process parameters. Compared with traditional thermal catalysis, electrocatalysis, and plasma catalysis, the method adopted by the present invention has the advantages of mild reaction conditions, high synthesis efficiency, low energy consumption, and strong operational feasibility.

[0054] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0056] Figure 1 The specific synthesis device that can be used in the method for electrothermal catalytic synthesis of ammonia provided by the present invention is shown.

[0057] Reference numerals:

[0058] Quartz tube 1, conductive filter element 2, catalyst 3, electrode 4, thermocouple 5, DC power supply 6, air inlet 7-1, and air outlet 7-2. DETAILED DESCRIPTION

[0059] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be understood as limiting the present invention.

[0060] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. Further, in the description of the present invention, unless otherwise specified, the meaning of "plurality" is two or more.

[0061] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0062] In order to make the present invention more easily understood, certain technical and scientific terms are specifically defined below. Unless otherwise clearly defined elsewhere in this document, all other technical and scientific terms used herein have the meanings commonly understood by those skilled in the art to which the present invention belongs.

[0063] In this document, the terms “include” or “comprising” are open expressions, that is, including the contents specified in the present invention but not excluding other contents.

[0064] As used herein, the terms "optionally", "optional" or "optionally" generally mean that the subsequently described event or circumstance may but need not occur, and that the description includes instances where the event or circumstance occurs and instances where it does not.

[0065] According to an embodiment of the present invention, a first aspect of the present invention provides a method for synthesizing ammonia by electrothermal catalysis, comprising the following steps:

[0066] Nitrogen and hydrogen are brought into contact with a catalyst under an electric state to react and obtain ammonia;

[0067] Wherein, the catalyst comprises an active component and a catalyst carrier;

[0068] The active component includes a transition metal, and the transition metal includes one of ruthenium, iron, cobalt or nickel;

[0069] The catalyst support includes a first rare earth hydride ReH x Or rare earth oxyhydride ReH 3-2y O y ;

[0070] Wherein, Re is a rare earth element; 2≤x≤3; 0 <y≤1。

[0071] The present invention can change the electronic structure of the catalyst and reactants by applying an external electric field, accelerate the electron transfer on the catalyst surface, and thus promote the catalytic reaction; regulating the external electric field can also change the adsorption behavior and kinetic parameters of the reactants and intermediates, affect the breaking and formation of chemical bonds on the catalyst surface, and thus realize the manipulation of the reaction path. In addition, the present invention also screened the electrothermal catalyst, and the catalyst carriers rare earth hydrides and rare earth oxyhydrides used have high hydrogen anion mobility. During the reaction, the catalyst carriers rare earth hydrides and rare earth oxyhydrides have strong metal-support interactions with transition metals, resulting in electron transfer from the carrier to the transition metal, and under the action of the electric field, the reaction mechanism will change from a dissociation mechanism in the absence of an electric field to an association mechanism in the presence of an electric field. Finally, the present invention also rationally designs the process parameters, thereby achieving efficient ammonia synthesis under mild conditions.

[0072] According to a specific embodiment of the present invention, the rare earth metal elements (scandium, yttrium, lanthanum, praseodymium, neodymium, promethium, samarium, europium, and gadolinium) in the first rare earth hydride or the rare earth oxyhydride are replaced with alkali metal elements (including lithium, sodium, potassium, and cesium) or alkaline earth metal elements (including beryllium, magnesium, calcium, strontium, and barium), and the catalyst can also exhibit better catalytic performance.

[0073] According to a specific embodiment of the present invention, the value of x is not particularly limited. As some specific examples, the value of x may be 2, 2.2, 2.4, 2.6, 2.8, 3, etc.; the value of y is not particularly limited. As some specific examples, the value of y may be 0.2, 0.4, 0.6, 0.8, 1, etc.

[0074] According to a specific embodiment of the present invention, the content of the active component is 0.1%-20% of the total mass of the catalyst. As some specific examples, the content of the active component may be 0.1%, 0.5%, 1%, 5%, 10%, 15%, 20% and the like of the total mass of the catalyst.

[0075] According to a specific embodiment of the present invention, the volume ratio of nitrogen and hydrogen is (1-9):(9-1). As some specific examples, the volume ratio of nitrogen and hydrogen may be 1:9, 1:5, 1:1, 5:1, 9:1, etc.

[0076] According to a specific embodiment of the present invention, the reaction temperature is 50°C-500°C. As some specific examples, the reaction temperature may be 50°C, 100°C, 200°C, 300°C, 400°C, 500°C, etc.

[0077] According to a specific embodiment of the present invention, the pressure of the reaction is 0.1 MPa-30 MPa. As some specific examples, the pressure of the reaction may be 0.1 MPa, 0.5 MPa, 1 MPa, 5 MPa, 10 MPa, 20 MPa, 30 MPa, etc.

[0078] According to a specific embodiment of the present invention, the space velocity of the nitrogen and hydrogen is 1000 mL·g· cat -1 ·h -1 -1000000mL·g· cat -1 ·h -1 As some specific examples, the space velocity of the nitrogen and hydrogen can be 1000 mL·g· cat -1 ·h -1 、10000mL·g· cat -1 ·h -1 、100000mL·g· cat -1 ·h -1 、1000000mL·g· cat -1 ·h -1 Etc. Wherein, "space velocity" should be understood as the amount of raw material passing through a unit catalyst per unit time.

[0079] According to a specific embodiment of the present invention, the voltage used in the reaction is 0-60V, the current is 0-10A, and both the voltage and the current are not 0. The synthesis efficiency of ammonia can be improved by controlling the current flowing through the catalyst. As some specific examples, the voltage used in the reaction may be 10V, 20V, 30V, 40V, 50V, 60V, etc.; the current may be 2A, 4A, 6A, 8A, 10A, etc.

[0080] According to a specific embodiment of the present invention, the method further comprises the following steps of preparing the first rare earth hydride:

[0081] Carrying out a hydrogenation reaction on a rare earth hydride precursor to obtain the first rare earth hydride;

[0082] Wherein, the rare earth hydride precursor includes at least one of scandium, yttrium, lanthanum, praseodymium, neodymium, promethium, samarium, europium and gadolinium.

[0083] According to a specific embodiment of the present invention, the temperature of the hydrogenation reaction is 30°C-800°C. As some specific examples, the temperature of the hydrogenation reaction may be 30°C, 100°C, 200°C, 300°C, 400°C, 500°C, 600°C, 700°C, 800°C, etc.

[0084] According to a specific embodiment of the present invention, the pressure of the hydrogenation reaction is 0.5 MPa-5 MPa. As some specific examples, the pressure of the hydrogenation reaction may be 0.5 MPa, 1 MPa, 2 MPa, 3 MPa, 4 MPa, 5 MPa, etc.

[0085] According to a specific embodiment of the present invention, the time of the hydrogenation reaction is 2h-12h. As some specific examples, the time of the hydrogenation reaction can be 2h, 4h, 6h, 8h, 10h, 12h, etc.

[0086] According to a specific embodiment of the present invention, the method further comprises the following steps of preparing the rare earth oxyhydride:

[0087] The rare earth oxide is once calcined in an inert atmosphere;

[0088] A second rare earth hydride is added and calcined twice in hydrogen to obtain the rare earth oxyhydride.

[0089] According to a specific embodiment of the present invention, the type of the rare earth oxide is not particularly limited. As some specific examples, the rare earth oxide includes at least one of scandium oxide, yttrium oxide, lanthanum oxide, praseodymium oxide, neodymium oxide, promethium oxide, samarium oxide, europium oxide, and gadolinium oxide.

[0090] According to a specific embodiment of the present invention, the type of the second rare earth hydride is not particularly limited. As some specific examples, the second rare earth hydride includes at least one of scandium hydride, yttrium hydride, lanthanum hydride, praseodymium hydride, neodymium hydride, promethium hydride, samarium hydride, europium hydride, and gadolinium hydride.

[0091] According to a specific embodiment of the present invention, the molar ratio of the second rare earth hydride and the rare earth oxide is (1-30):1. As some specific examples, the molar ratio of the second rare earth hydride and the rare earth oxide may be 1:1, 5:1, 10:1, 20:1, 30:1, etc.

[0092] According to a specific embodiment of the present invention, the temperature of the primary calcination is 200°C-1200°C. As some specific examples, the temperature of the primary calcination may be 200°C, 400°C, 600°C, 800°C, 1000°C, 1200°C, etc.

[0093] According to a specific embodiment of the present invention, the time of the first calcination is 1 hour to 20 hours. As some specific examples, the time of the first calcination can be 1 hour, 5 hours, 10 hours, 15 hours, 20 hours, etc.

[0094] According to a specific embodiment of the present invention, the temperature of the secondary calcination is 400°C-1000°C. As some specific examples, the temperature of the secondary calcination may be 400°C, 600°C, 800°C, 1000°C, etc.

[0095] According to a specific embodiment of the present invention, the time of the secondary roasting is 10h-24h. As some specific examples, the time of the secondary roasting can be 10h, 12h, 15h, 18h, 21h, 24h, etc.

[0096] According to a specific embodiment of the present invention, the pressure of the secondary calcination is 0.1 MPa-2 MPa. As some specific examples, the pressure of the secondary calcination may be 0.1 MPa, 0.5 MPa, 1 MPa, 1.5 MPa, 2 MPa, etc.

[0097] According to a specific embodiment of the present invention, the method further comprises the following steps of preparing the catalyst:

[0098] Adding a transition metal precursor into a solvent, adding the catalyst support for impregnation, drying, and reducing with hydrogen to obtain the catalyst;

[0099] Wherein, the transition metal precursor is used to provide the active component.

[0100] According to a specific embodiment of the present invention, the type of the transition metal precursor is not particularly limited. As some specific examples, the transition metal precursor includes at least one of chloride, nitrate, acetylacetonate, and carbonyl complex.

[0101] According to a specific embodiment of the present invention, the type of the chloride is not particularly limited. As some specific examples, the chloride includes at least one of ruthenium trichloride, ferric chloride, cobalt chloride, and nickel chloride.

[0102] According to a specific embodiment of the present invention, the type of the nitrate is not particularly limited. As some specific examples, the nitrate includes at least one of ruthenium nitrosyl nitrate, iron nitrate, cobalt nitrate, and nickel nitrate.

[0103] According to a specific embodiment of the present invention, the type of the acetylacetonate is not particularly limited. As some specific examples, the acetylacetonate includes at least one of ruthenium acetylacetonate, iron acetylacetonate, cobalt acetylacetonate, and nickel acetylacetonate.

[0104] According to a specific embodiment of the present invention, the type of the carbonyl complex is not particularly limited. As some specific examples, the carbonyl complex includes at least one of triruthenium dodecacarbonyl, diiron nonacarbonyl, dicobalt octacarbonyl, and nickel tetracarbonyl.

[0105] According to a specific embodiment of the present invention, the immersion temperature is 20°C-100°C. As some specific examples, the immersion temperature may be 20°C, 40°C, 60°C, 80°C, 100°C, etc.

[0106] According to a specific embodiment of the present invention, the immersion time is 0.3h-12h. As some specific examples, the immersion time may be 0.3h, 1h, 4h, 8h, 12h, etc.

[0107] According to a specific embodiment of the present invention, the type of the solvent is not particularly limited. As some specific examples, the solvent includes at least one of methanol, ethanol or tetrahydrofuran.

[0108] According to a specific embodiment of the present invention, the drying temperature is 60°C-120°C. As some specific examples, the drying temperature may be 60°C, 80°C, 100°C, 120°C, etc.

[0109] According to a specific embodiment of the present invention, the drying time is 0.5h-12h. As some specific examples, the drying time may be 0.5h, 1h, 4h, 8h, 12h, etc.

[0110] According to a specific embodiment of the present invention, the temperature of the hydrogen reduction is 200°C-600°C. As some specific examples, the temperature of the hydrogen reduction may be 200°C, 400°C, 600°C, etc.

[0111] According to a specific embodiment of the present invention, the time for the hydrogen reduction is 1 h-12 h. As some specific examples, the time for the hydrogen reduction may be 1 h, 4 h, 8 h, 12 h, etc.

[0112] According to a specific embodiment of the present invention, the hydrogen flow rate in the hydrogen reduction is 30 mL min -1 -100mL·min -1 As some specific examples, the hydrogen flow rate in the hydrogen reduction may be 30 mL min -1 、60mL·min -1 、90mL·min -1 、100mL·min -1 wait.

[0113] According to a specific embodiment of the present invention, the method for synthesizing ammonia by electrothermal catalysis can be specifically operated as follows (see Figure 1): The catalyst 3 is placed in a quartz tube 1, and the two ends are clamped with a conductive filter element 2, and then the electrode 4 is pressed against the conductive filter element 2, and the electrode 4 and the conductive filter element 2 form a current collector. The two ends of the electrode 4 are connected to a DC power supply 6, and the current flows through the catalyst 3 through the current collector to form a closed loop, thereby performing efficient ammonia synthesis under mild conditions. Two openings are reserved on both sides of the quartz tube 1, which serve as the inlet 7-1 and the outlet 7-2 of the reaction gas respectively. The inlet gas is a nitrogen-hydrogen mixed gas, and the outlet gas is connected to a conductivity meter. A thermocouple 5 is inserted into the middle opening of the reaction tube to monitor the ambient temperature of the reaction.

[0114] According to a specific embodiment of the present invention, the type of the electrode 4 is not particularly limited. As some specific examples, the electrode 4 includes at least one of a copper electrode, an aluminum electrode or a stainless steel electrode.

[0115] According to a specific embodiment of the present invention, the type of the conductive filter element 2 is not particularly limited. As some specific examples, the conductive filter element 2 includes at least one of a copper filter element, an aluminum filter element or a stainless steel filter element.

[0116] The scheme of the present invention will be explained below in conjunction with the embodiments. It will be appreciated by those skilled in the art that the following embodiments are only used to illustrate the present invention and should not be considered as limiting the scope of the present invention. Where specific techniques or conditions are not indicated in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. The reagents or instruments used are not indicated by the manufacturer and are all conventional products that can be obtained commercially.

[0117] Example 1

[0118] Weigh 200 mg of metallic lanthanum accurately, and hydrogenate it in hydrogen at 700°C and 5 MPa for 10 h to obtain lanthanum hydride (LaH3). Weigh 3.94 mg of ruthenium acetylacetonate and dissolve it in ethanol solution, immerse 200 mg of LaH3 in the above solution, and keep it at 30°C for 12 h. Dry the obtained sample at 80°C for 12 h and condense it at 60 mL min -1 The reaction mixture was reduced in hydrogen at 600°C for 2 h to obtain a ruthenium catalyst supported on lanthanum hydride (0.5% Ru / LaH3).

[0119] Accurately weigh 200 mg of Ru / LaH3, load it into a quartz reactor, clamp it with a copper conductive filter, and then use a stainless steel electrode to hold the copper conductive filter. Connect a DC power supply at both ends of the stainless steel and perform ammonia synthesis reaction at a working current of 20 mA. The reaction temperature is 200 ° C, N2:H2=1:3, the reaction pressure is 1.0 MPa, and the reaction gas space velocity is 36000 mL·g· cat -1 ·h -1 .

[0120] Example 2

[0121] Accurately weigh 153 mg of lanthanum oxide and calcine it at 1200°C in argon for 10 h. Weigh 200 mg of lanthanum hydride, mix it with the calcined lanthanum oxide, and calcine it in hydrogen at 800°C and 1.5 MPa for 20 h to obtain rare earth hydride (LaHO). Weigh 3.94 mg of ruthenium acetylacetonate and dissolve it in ethanol solution, immerse 200 mg of LaHO in the above solution, and keep it at 30°C for 12 h. Dry the obtained sample at 80°C for 12 h and precipitate it at 60 mL min -1 The lanthanum oxyhydride-supported ruthenium catalyst (0.5% Ru / LaHO) was obtained by reduction in hydrogen at 400°C for 2h.

[0122] Accurately weigh 200 mg of Ru / LaHO, load it into a quartz reactor, clamp it with a copper conductive filter, and then use a stainless steel electrode to hold the copper conductive filter. Connect a DC power supply at both ends of the stainless steel and perform ammonia synthesis reaction at a working current of 20 mA. The reaction temperature is 200 ° C, N2:H2=1:3, the reaction pressure is 1.0 MPa, and the reaction gas space velocity is 36000 mL·g· cat -1 ·h -1 .

[0123] Example 3

[0124] Weigh 138 mg of lanthanum oxide accurately and calcine it at 1200°C for 10 h in argon. Weigh 200 mg of lanthanum hydride, mix it with the calcined lanthanum oxide, and calcine it at 800°C and 1.5 MPa in hydrogen for 20 h to obtain rare earth oxyhydride (LaH 2.5 O 0.25 ). Weigh 3.94 mg of ruthenium acetylacetonate and dissolve it in ethanol solution. Add 200 mg of LaH 2.5 O 0.25 Immerse in the above solution and keep at 30°C for 12 h. Dry the obtained sample at 80°C for 12 h and -1 The ruthenium catalyst supported by lanthanum oxyhydride (0.5% Ru / LaH 2.5 O 0.25 ).

[0125] Accurately weigh 200 mg Ru / LaH 2.5 O 0.25 , loaded into a quartz reactor, clamped with a copper conductive filter, and then a stainless steel electrode was used to hold the copper conductive filter. A DC power supply was connected to both ends of the stainless steel, and ammonia synthesis reaction was carried out at a working current of 20 mA. The reaction temperature was 200°C, N2:H2=1:3, the reaction pressure was 1.0MPa, and the reaction gas space velocity was 36000mL·g· cat -1 ·h-1 .

[0126] Example 4

[0127] Ru / LaH 2.5 O 0.25 The preparation is the same as in Example 3. Accurately weigh 200 mg of Ru / LaH 2.5 O 0.25 , loaded into a quartz reactor, clamped with a copper conductive filter, and then a stainless steel electrode was used to hold the copper conductive filter. A DC power supply was connected to both ends of the stainless steel, and ammonia synthesis reaction was carried out at a working current of 50 mA. The reaction temperature was 200°C, N2:H2=1:3, the reaction pressure was 1.0MPa, and the reaction gas space velocity was 36000mL·g· cat -1 ·h -1 .

[0128] Example 5

[0129] Ru / LaH 2.5 O 0.25 The preparation is the same as in Example 3. Accurately weigh 200 mg of Ru / LaH 2.5 O 0.25 , loaded into a quartz reactor, clamped with a copper conductive filter, and then a stainless steel electrode was used to hold the copper conductive filter. A DC power supply was connected to both ends of the stainless steel, and ammonia synthesis reaction was carried out at a working current of 500mA. The reaction temperature was 200℃, N2:H2=1:3, the reaction pressure was 1.0MPa, and the reaction gas space velocity was 36000mL·g· cat -1 ·h -1 .

[0130] Example 6

[0131] Ru / LaH 2.5 O 0.25 The preparation is the same as in Example 3. Accurately weigh 200 mg of Ru / LaH 2.5 O 0.25 , put it into a quartz reactor, clamp it with a copper conductive filter, and then use a stainless steel electrode to hold the copper conductive filter. Connect a DC power supply at both ends of the stainless steel, and perform ammonia synthesis reaction at a working current of 50mA. The reaction temperature is 250℃, N2:H2=1:3, the reaction pressure is 1.0MPa, and the reaction gas space velocity is 36000mL·g· cat -1 ·h -1 .

[0132] Example 7

[0133] Ru / LaH 2.5 O 0.25The preparation is the same as in Example 3. Accurately weigh 200 mg of Ru / LaH 2.5 O 0.25 , put it into a quartz reactor, clamp it with a copper conductive filter, and then use a stainless steel electrode to hold the copper conductive filter. Connect a DC power supply at both ends of the stainless steel, and perform ammonia synthesis reaction at a working current of 50mA. The reaction temperature is 300℃, N2:H2=1:3, the reaction pressure is 1.0MPa, and the reaction gas space velocity is 36000mL·g· cat -1 ·h -1 .

[0134] Comparative Example 1

[0135] Ru / LaH 2.5 O 0.25 The preparation is the same as in Example 3. Ammonia synthesis is carried out by conventional thermal catalysis. 200 mg Ru / LaH 2.5 O 0.25 The reaction temperature was maintained at 300°C by an electric furnace without applying current, N2:H2=1:3, the reaction pressure was 1.0 MPa, and the reaction gas space velocity was 36000 mL·g· cat -1 ·h -1 .

[0136] Comparative Example 2

[0137] The only difference between this comparative example and Example 1 is that lanthanum is used as a catalyst carrier instead of lanthanum hydride to obtain a lanthanum-supported ruthenium catalyst (0.5% Ru / La).

[0138] Accurately weigh 200 mg of Ru / La, load it into a quartz reactor, clamp it with a copper conductive filter, and then use a stainless steel electrode to hold the copper conductive filter. Connect a DC power supply at both ends of the stainless steel and perform ammonia synthesis reaction at a working current of 20 mA. The reaction temperature is 200 ° C, N2:H2=1:3, the reaction pressure is 1.0 MPa, and the reaction gas space velocity is 36000 mL·g· cat -1 ·h -1 .

[0139] A conductivity meter was installed at the product outlet of the reaction device to detect the ammonia production rates of the examples and comparative examples. The ammonia production rates of Examples 1-7 and Comparative Examples 1-2 are shown in Table 1.

[0140] Table 1

[0141] <![CDATA[Ammonia production rate (μmol g cat -1 h -1 )]]> Example 1 2003 Example 2 2219 Example 3 2452 Example 4 2817 Example 5 3108 Example 6 5225 Example 7 9339 Comparative Example 1 1519 Comparative Example 2 1325

[0142] It can be seen from the data in Table 1 that Examples 1-7 of the present invention all have high ammonia production rates under mild reaction conditions. The ammonia production rate of Comparative Example 1 is significantly lower than that of the Examples, indicating that if an external electric field is not applied, the efficiency of ammonia synthesis by the traditional thermal catalytic method is low; the ammonia production rate of Comparative Example 2 is significantly lower than that of the Examples, indicating that the selection of catalysts has a huge impact on the rate of ammonia synthesis, and the catalytic performance of rare earth hydrides or rare earth oxyhydrides is significantly better than that of their metal elements.

[0143] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0144] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for synthesizing ammonia by electrothermal catalysis, characterized in that: The steps include: Nitrogen and hydrogen are brought into contact with a catalyst under an electric state to react and obtain ammonia; Wherein, the catalyst comprises an active component and a catalyst carrier; The active component includes a transition metal, and the transition metal includes one of ruthenium, iron, cobalt or nickel; The catalyst support includes a first rare earth hydride ReH x Or rare earth oxyhydride ReH 3-2y O y ; Wherein, Re is a rare earth element; 2≤x≤3; 0 <y≤1。 2. The method according to claim 1, characterized in that The content of the active component is 0.1%-20% of the total mass of the catalyst; Optionally, the volume ratio of nitrogen to hydrogen is (1-9):(9-1).

3. The method according to claim 1, characterized in that The reaction temperature is 50°C-500°C; Optionally, the reaction pressure is 0.1 MPa-30 MPa; Optionally, the space velocity of the nitrogen and hydrogen is 1000 mL·g· cat -1 ·h -1 -1000000mL·g· cat -1 ·h -1 ; Optionally, the voltage used in the reaction is 0-60V, and the current is 0-10A, and both the voltage and the current are not zero.

4. The method according to claim 1, characterized in that: The method further comprises the following steps of preparing the first rare earth hydride: Carrying out a hydrogenation reaction on a rare earth hydride precursor to obtain the first rare earth hydride; Wherein, the rare earth hydride precursor includes at least one of scandium, yttrium, lanthanum, praseodymium, neodymium, promethium, samarium, europium, and gadolinium; Optionally, the temperature of the hydrogenation reaction is 30°C-800°C; Optionally, the pressure of the hydrogenation reaction is 0.5MPa-5MPa; Optionally, the hydrogenation reaction time is 2h-12h.

5. The method according to claim 1, characterized in that: The method further comprises the following steps of preparing the rare earth oxyhydride: The rare earth oxide is once calcined in an inert atmosphere; adding a second rare earth hydride and performing secondary calcination in hydrogen to obtain the rare earth oxyhydride; Optionally, the rare earth oxide includes at least one of scandium oxide, yttrium oxide, lanthanum oxide, praseodymium oxide, neodymium oxide, promethium oxide, samarium oxide, europium oxide, and gadolinium oxide; Optionally, the second rare earth hydride includes at least one of scandium hydride, yttrium hydride, lanthanum hydride, praseodymium hydride, neodymium hydride, promethium hydride, samarium hydride, europium hydride, and gadolinium hydride.

6. The method according to claim 5, characterized in that The molar ratio of the second rare earth hydride to the rare earth oxide is (1-30): 1; Optionally, the primary calcination temperature is 200°C-1200°C; Optionally, the time of the first calcination is 1h-20h; Optionally, the secondary calcination temperature is 400°C-1000°C; Optionally, the secondary roasting time is 10h-24h; Optionally, the secondary calcination pressure is 0.1 MPa-2 MPa.

7. The method according to claim 1, characterized in that The method further comprises the following steps of preparing the catalyst: Adding a transition metal precursor into a solvent, adding the catalyst support for impregnation, drying, and reducing with hydrogen to obtain the catalyst; Wherein, the transition metal precursor is used to provide the active component; Optionally, the transition metal precursor includes at least one of chloride, nitrate, acetylacetonate, and carbonyl complex; Optionally, the chloride includes at least one of ruthenium trichloride, ferric chloride, cobalt chloride, and nickel chloride; Optionally, the nitrate includes at least one of ruthenium nitrosyl nitrate, iron nitrate, cobalt nitrate, and nickel nitrate; Optionally, the acetylacetonate includes at least one of ruthenium acetylacetonate, iron acetylacetonate, cobalt acetylacetonate, and nickel acetylacetonate; Optionally, the carbonyl complex includes at least one of triruthenium dodecacarbonyl, diiron nonacarbonyl, dicobalt octacarbonyl, and nickel tetracarbonyl.

8. The method according to claim 7, characterized in that The immersion temperature is 20°C-100°C; Optionally, the immersion time is 0.3h-12h; Optionally, the solvent comprises at least one of methanol, ethanol or tetrahydrofuran.

9. The method according to claim 7, characterized in that: The drying temperature is 60°C-120°C; Optionally, the drying time is 0.5h-12h.

10. The method according to claim 7, characterized in that The temperature of the hydrogen reduction is 200°C-600°C; Optionally, the hydrogen reduction time is 1h-12h; Optionally, the hydrogen flow rate in the hydrogen reduction is 30 mL min -1 -100mL·min -1 .

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