CN113318750A - Lithium-doped two-dimensional iron-molybdenum catalyst for synthesizing ammonia gas by thermally catalyzing nitrogen and hydrogen through mobile phase and preparation method thereof - Google Patents

Lithium-doped two-dimensional iron-molybdenum catalyst for synthesizing ammonia gas by thermally catalyzing nitrogen and hydrogen through mobile phase and preparation method thereof Download PDF

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CN113318750A
CN113318750A CN202110691226.0A CN202110691226A CN113318750A CN 113318750 A CN113318750 A CN 113318750A CN 202110691226 A CN202110691226 A CN 202110691226A CN 113318750 A CN113318750 A CN 113318750A
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李路
高卓炀
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Jilin University
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Abstract

A lithium-doped two-dimensional iron-molybdenum catalyst for synthesizing ammonia gas by thermally catalyzing nitrogen and hydrogen with a mobile phase and a preparation method thereof belong to the technical field of ammonia synthesis catalysis. The invention uses MoO2Vacuum calcining treatment, and loading iron ions and iron atoms to MoO2Mixing the surface of the substrate with lithium-containing reducing agent uniformly, calcining the mixture at high temperature in vacuum, and washing the calcined product with acid or water to dope lithium into MoO2Thereby peeling the two-dimensional catalyst to obtain the lithium-doped two-dimensional iron-molybdenum catalyst. According to the invention, a large amount of electrons are introduced into the catalyst by doping lithium, the catalyst has iron-molybdenum double activation sites, and can be subjected to mobile phase catalysis in a fixed bed reactor, and the catalyst can be used at high temperatureAnd can catalyze nitrogen and hydrogen to synthesize ammonia for a long time under high pressure. Wherein, the generation amount of ammonia gas of the lithium-doped two-dimensional iron-molybdenum catalyst can reach 3007.11umol g‑1*h‑1The ammonia gas generation amount of the acid-treated lithium-doped two-dimensional iron-molybdenum catalyst can reach 3207.61umol g‑1*h‑1。

Description

Lithium-doped two-dimensional iron-molybdenum catalyst for synthesizing ammonia gas by thermally catalyzing nitrogen and hydrogen through mobile phase and preparation method thereof
Technical Field
The invention belongs to the technical field of synthetic ammonia catalysis, and particularly relates to a lithium-doped two-dimensional iron-molybdenum catalyst for synthesizing ammonia gas by thermally catalyzing nitrogen and hydrogen through a mobile phase and a preparation method thereof.
Background
Ammonia has a very important influence on human sustainable development and is one of important chemical fertilizer raw materials and chemical raw materials in the world. Synthesis of ammonia (N) by the Habor-Bosch Process2+3H2＝2NH3350-500 ℃ and 50-200 bar), but still consumes a lot of energy in the field of ammonia synthesis, and faces a lot of challenges. Although the biocatalysis, the electrocatalysis, the photocatalysis and the thermocatalysis are developed in the field of ammonia synthesis at present, each catalytic direction has room for improvement, for example, an iron-based catalyst is low in price but low in catalytic efficiency, a ruthenium-based catalyst is high in activity but high in price and has a strong inhibition effect on hydrogen, and a thermocatalysis effect is good but high in energy consumption.
At present, ammonia synthesis towers are common in the chemical industry of China, a large amount of solid particle catalysts are stacked together to form a particle bed layer, and gas flow is subjected to gas-solid phase catalysis through the bed layer, so that a fixed bed reactor can effectively perform heterogeneous catalytic reaction.
However, the rotation system of leguminous plants and non-leguminous plants is still maintained in China from ancient times to present, and ancient people record that leguminous plants have the function of 'soil maturity and fertility'. Compared with the industrial nitrogen fixation method, the biological nitrogen preparation can be carried out at normal temperature and normal pressure. Various researches show that two independent enzyme proteins can be separated from the rhizobium azotase of the soybean, wherein one enzyme protein is ferromolybdenum, the other enzyme protein is ferritin, the two enzyme proteins have azotase activity only when being combined together, and the azotase is inactive when being separated. In the synergistic effect of the two, ferritin provides electrons for ferromolybdenum protein, and the ferromolybdenum protein plays a catalytic and complexing role in catalyzing nitrogen (N)2+8e-+8H++16Mg·ATP+16H2O→2NH3 +H2+16 Mg. ADP +16Pi), i.e. electrons and hydrogen in the case of ATP-supplied energyIon transfer to N by nitrogenase2Reducing them to NH3. At present, Michikazu Hara et al published a title "Synthesis of ammonia by Using a Stable Electron Compound as an Electron Donor and a reversible Hydrogen storage", in Nature Chemistry journal (2012, No. 4, pp. 934-940), and prepared a ruthenium-supported Electron Compound activated Nitrogen. Michikazu Hara et al, later, published a title "Synthesis of ammonia at 50 ℃ with solid solution" in Nature Communications journal (20: 15868-15876 of 2020) by introducing F-The electron-pushing capacity of the CaFH solid solution is enhanced, so that ammonia can be synthesized under low-temperature conditions, and the ammonia is compared with an industrial iron-based catalyst in the article. However, the method for preparing the catalyst by Michikazu Hara is harsh and is not suitable for industrial mass production.
Therefore, there is a need to design a catalyst that can have a large number of electrons to maintain the excellent activity of the catalyst and to stabilize the existing catalyst to solve the current problems.
Disclosure of Invention
In order to solve the problems, the invention aims to provide a lithium-doped two-dimensional iron-molybdenum catalyst for synthesizing ammonia gas by thermally catalyzing nitrogen and hydrogen through a mobile phase and a preparation method thereof.
The invention uses MoO2Vacuum calcining treatment, and loading iron ions and iron atoms to MoO2Mixing the surface of the substrate with lithium-containing reducing agent uniformly, calcining the mixture at high temperature in vacuum, and washing the calcined product with acid or water to dope lithium into MoO2Thereby peeling the two-dimensional catalyst to obtain the lithium-doped two-dimensional iron-molybdenum catalyst. According to the invention, a large amount of electrons are introduced into the catalyst through lithium doping, the catalyst has iron-molybdenum double activation sites, and can be subjected to mobile phase catalysis in a fixed bed reactor, and the catalyst can catalyze nitrogen and hydrogen to synthesize ammonia for a long time at high temperature and high pressure. The catalyst utilizes a small amount of iron, and has a simple structure and low price.
The invention relates to a preparation method of a lithium-doped two-dimensional iron-molybdenum catalyst for synthesizing ammonia gas by thermally catalyzing nitrogen and hydrogen with a mobile phase, which comprises the following steps:
(1) iron molybdenum catalyst precursorPreparation of the body: adding 0.4-5 g of MoO2Calcining the ground mixture for 1 to 5 hours at 300 to 800 ℃ in vacuum, and then placing the calcined mixture in 0.1 to 2g/L of organic solvent solution of iron salt in inert atmosphere (N)2Or Ar) stirring and dipping for 3-10 h, and performing rotary evaporation and evaporation to dryness and then vacuum drying to obtain an iron-molybdenum catalyst precursor; the organic solvent solution of ferric salt is FeCl3Ethanol solution of (3), Fe2(SO4)3Ethanol solution of (3), Fe3(CO)12THF solution of (1), Fe2(CO)9THF solution of (1), FeC4H7O5·nH2Ethanol solution of O, FePO4Ethanol solution of (3), Fe2(C2O4)3Ethanol solution of (2), FeSO4Ethanol solution of (3), Fe3(PO4)2·nH2Ethanol solution of O, FeBr3Ethanol solution of (D), FeCl2Ethanol solution of (5) FeBr2One of the ethanol solutions of (a);
(2) preparing a lithium-doped two-dimensional iron-molybdenum catalyst: mixing the iron-molybdenum catalyst precursor obtained in the step (1) with lithium salt in a molar ratio of 1: 5-13, grinding and uniformly mixing, slowly heating to 200-600 ℃ in a vacuum state, keeping for 1-10 h (the heating rate is 0.2-2 ℃/min), cooling to room temperature, and sealing; slowly injecting a little deionized water into the reaction system under the ice-water bath condition to immerse the reaction product, and transferring to 50-1000 mL of concentrated hydrochloric acid (the density is 1.179 g/cm) containing 0-10 mL after the reaction is completed3) Performing ultrasonic treatment for 2-10 min in the deionized water; washing the reaction product with deionized water for 3-5 times, and then drying in vacuum to obtain a lithium-doped two-dimensional iron-molybdenum catalyst; the sample washed without hydrochloric acid was named Li-Fe-MoO2The sample washed with hydrochloric acid was named H+-Li-Fe-MoO2(ii) a The lithium salt is LiH or C4H9Li、LiAlH4、LiBH4One of (1);
(3) thermal catalytic synthesis of ammonia: 0.1-1 g of the lithium-doped two-dimensional iron-molybdenum catalyst prepared in the step (2) is pressed into tablets under 2-30 MPa for 1-30 min, and the pressed tablets are taken out, smashed and sieved; selecting 20-60 mesh catalyst particles, filling the catalyst particles into a quartz reaction tube (inner diameter is 4-8 mm)The filling height of the catalyst is 2-3 times of the inner diameter, and the quartz reaction tube is sealed and then transferred to a fixed bed reactor; or 0.01-1 g of catalyst and 0.4-1.0 g of quartz sand of 20-140 meshes are uniformly mixed in a glove box, filled into a quartz reaction tube and sealed, and then transferred to a fixed bed reactor; the method comprises the following steps of: 3 is N2And H2The mixed gas is reaction gas, the flow rate is 5-100 mL/min, and the pressure is kept at 0.1-4 MPa; after the airflow is stable, the temperature is raised to 50-800 ℃ for catalytic reaction for 1-120 h, and the temperature raising rate is 3-5 ℃/min, so that the thermal catalytic synthesis of ammonia is completed.
MoO used in the invention2LiH, hydrochloric acid, sulfuric acid, quartz sand and other metals are commercially available.
Drawings
FIG. 1: is Li-MoO2、Li-Fe-MoO2And H+-Li-Fe-MoO2(wherein Li-Fe-MoO)2Is a lithium-doped two-dimensional iron-molybdenum catalyst, Li-MoO2Is a lithium-doped molybdenum dioxide catalyst, H+-Li-Fe-MoO2Lithium doped two-dimensional iron molybdenum catalyst washed with hydrochloric acid) and standard MoO2XRD pattern of (a); illustrates the MoO2The molybdenum at the edge of the lithium salt is reduced into molybdenum metal, MoO by the action of the reduced lithium salt LiH2The bulk phase has good crystallinity, the framework is not damaged, and the main diffraction peaks are shifted to small angles to indicate that lithium enters MoO2In the crystal lattice. MoO2After loading with iron, LiH is preferentially attracted by iron, bridging with MoO via iron2Reaction, MoO2The bulk phase crystal lattice is still intact, the edge metal molybdenum exists at the same time, and the main peak shifts; exposing a large amount of edge molybdenum after acid washing;
FIG. 2: (a) is Li-Fe-MoO2A transmission diagram of Li-Fe-MoO2Is a layered two-dimensional material; (b) is Li-Fe-MoO2STEM dark field map of (1); (c) is Li-Fe-MoO2The elemental distribution of O of (1); (d) is Li-Fe-MoO2The elemental distribution of Fe of (1); (e) is Li-Fe-MoO2The element distribution of Mo of (a); (b) the scale bar of the graphs (c), (d) and (e) is 500nm, which shows that Fe, O and Mo are uniformly distributed; corresponding to example 3;
FIG. 3: is Li-Fe-MoO2High resolution transmission diagram ofLi-Fe-MoO2The edge of (a) can see an obvious number of layers, 7-9 molecular layers, corresponding to example 3;
FIG. 4: (a) is H+-Li-Fe-MoO2Transmission diagram of (A), showing H after pickling+-Li-Fe-MoO2Still a layered two-dimensional material; (b) is H+-Li-Fe-MoO2STEM dark field map of (1); (c) is H+-Li-Fe-MoO2The elemental distribution of O of (1); (d) is H+-Li-Fe-MoO2The elemental distribution of Fe of (1); (e) is H+-Li-Fe-MoO2The element distribution of Mo of (a); (b) the scale bars of the graphs (c), (d) and (e) are 500nm, which shows that Fe, O and Mo are uniformly distributed, excessive acid washing cannot wash out all iron, and part of iron and MoO2Newly formed chemical bond stabilized in MoO2Above, corresponding to example 4;
FIG. 5: is Li-MoO2、Li-Fe-MoO2And H+-Li-Fe-MoO2The temperature programmed reaction of hydrogen (H) is shown in the figure+-Li-Fe-MoO2The adsorption capacity to hydrogen is strongest;
FIG. 6: is Li-MoO2、Li-Fe-MoO2And H+-Li-Fe-MoO2The electron spin resonance diagram shows that the three catalysts have a large number of lone-pair electrons which exist independently;
FIG. 7: is Li-MoO2、Li-Fe-MoO2、H+-Li-Fe-MoO2And MoO2FT-IR spectrum of (1), indicating the presence of MoO2And Li-MoO2Comparative Li-Fe-MoO2In addition to the pronounced Mo O, Mo-O-OH vibration, there is also the pronounced Fe O, Fe-O-Mo vibration, while H+-Li-Fe-MoO2Although the material is washed by hydrochloric acid, the obvious vibration of Fe-O, Fe-O-Mo still exists, and the excellent catalytic performance of the lithium-doped two-dimensional iron-molybdenum material is proved to be influenced by the coexistence of iron and molybdenum;
FIG. 8: standard NH determination by ion chromatography4 +Standard curve of concentration, the equation for the curve is Y-629748X-3641.5, Y represents NH measured by ion chromatography4 +Peak area, X represents NH4 +The unit of (1) is mmol/L; the curve passes throughMeasuring eight groups of NH of different concentrations4 +The series of peak areas are measured by ion chromatography, and NH is obtained by using the eight concentration/peak area mapping4 +Standard curve of concentration.
In each embodiment, the exhaust gas flows through the absorption liquid, and the ammonia gas generated by catalysis is dissolved in the absorption liquid to form NH4 +Taking out 1mL of tail gas absorption liquid of each embodiment, pumping into an ion chromatograph, and measuring NH in the tail gas absorption liquid4 +Substituting the peak area into a standard curve equation to obtain the tail gas absorption liquid NH4 +And (4) concentration.
FIG. 9: ammonia gas yield plot for the catalyst prepared in the examples, in umol g-1*h-1Corresponding to examples 1 to 9.
FIG. 10: ammonia gas yield plot for the catalyst prepared in the examples, in umol g-1*h-1Wherein Fe-1 corresponds to example 10, Fe-2 corresponds to example 3, Fe-3 corresponds to example 11, and Fe-4 corresponds to example 12.
FIG. 11: is Li-Fe-MoO2The ammonia yield plot over time, corresponding to example 13, shows Li-Fe-MoO2The catalytic performance of the catalyst is very stable.
FIG. 12: is Li-Fe-MoO2The activation energy graphs of (1) correspond to examples 14-17, and the activation energy can be obtained by taking one thousand times of reciprocal of different temperatures as the abscissa and taking the logarithm of the ammonia gas generation amount as the ordinate and multiplying the slope of the obtained trend line by R (8.314), which shows that the catalyst needs less activation energy and has good catalytic performance.
Detailed Description
The following examples are presented to further illustrate the practice and results of the invention and are not intended to limit the invention thereto.
Example 1
Preparation of iron-molybdenum catalyst precursor (named Fe-MoO)2) And their catalysis of N2、H2Synthesis of NH3。
(1) Preparing an iron-molybdenum catalyst precursor: 1g of MoO was weighed2Grinding, transferring into quartz boat, and placing in vacuumCalcining at 500 deg.C for 2 hr in an empty tube furnace, and placing in 14.48ml FeCl3In 0.5g/L of ethanol under an inert atmosphere (N)2Or Ar) stirring and dipping for 5h, evaporating to dryness by rotary evaporation, and then drying in vacuum to obtain an iron-molybdenum catalyst precursor Fe-MoO2；
(2) 30mg of Fe-MoO2Mixing with 0.5g and 140 mesh quartz sand in glove box, loading into quartz reaction tube (inner diameter of 6mm), sealing, transferring to fixed bed reactor, and adding N at molar ratio of 1:32And H2The mixed gas is used as reaction gas, the flow rate is 60mL/min, and the pressure is kept at 1 Mpa; after the gas flow is stable, heating to 400 ℃ for reaction for 3h (the heating rate is 4 ℃/min), thereby completing the thermocatalytic synthesis of ammonia; the final tail gas is diluted with 0.25mM of H2SO4Absorbing the solution, taking 1mL of tail gas absorption liquid to measure NH in the ion chromatogram4 +The peak area of (A) is substituted into the regression curve equation of FIG. 8 to obtain NH of the tail gas absorption liquid4 +The concentration is calculated, and the generation amount of ammonia gas can reach 95.99umol g-1*h-1。
Example 2
Preparation of lithium-doped molybdenum dioxide catalyst (named Li-MoO)2) And their catalysis of N2、H2Synthesis of NH3。
(1) Preparing a molybdenum dioxide catalyst precursor: 1g of MoO was weighed2Grinding, transferring the mixture into a quartz boat, placing the quartz boat into a vacuum tube furnace, and calcining the quartz boat for 2 hours at 500 ℃ to obtain a molybdenum dioxide catalyst precursor;
(2) grinding and uniformly mixing 0.8g of molybdenum dioxide catalyst and 0.4g of LiH, quickly transferring into a quartz bubble which is easy to seal, slowly heating to 450 ℃ in a vacuum state, keeping for 2h, wherein the heating rate is 1 ℃/min, sealing after cooling to room temperature, slowly injecting 5mL of deionized water into the quartz bubble under the condition of ice-water bath until the reaction is completed, transferring into 300mL of deionized water, and carrying out ultrasonic treatment for 8 min; washing the mixture for three times by using deionized water, and then drying the mixture in vacuum to obtain the lithium-doped two-dimensional molybdenum dioxide catalyst Li-MoO2；
(3) 30mg of Li-MoO20.5g, 140 meshMixing quartz sand in a glove box, loading into a quartz reaction tube (inner diameter of 6mm), sealing, transferring to a fixed bed reactor, and adding N at a molar ratio of 1:32And H2The mixed gas is used as reaction gas, the flow rate is 60mL/min, and the pressure is kept at 1 Mpa; after the gas flow is stable, heating to 400 ℃ for reaction for 3h (the heating rate is 4 ℃/min), thereby completing the thermocatalytic synthesis of ammonia; final tail gas consumption of 0.25mM H2SO4Absorbing the solution, taking 1mL of tail gas absorption liquid to measure NH in the ion chromatogram4 +The peak area of (A) is substituted into the regression curve equation of FIG. 8 to obtain NH of the tail gas absorption liquid4 +The concentration is calculated, and the generation amount of ammonia gas can reach 1191.48umol g-1*h-1。
Example 3
Preparation of lithium-doped two-dimensional iron-molybdenum catalyst (named Li-Fe-MoO)2) And their catalysis of N2、H2Synthesis of NH3。
(1) Preparing an iron-molybdenum catalyst precursor: same as example 1;
(2) preparing a lithium-doped two-dimensional iron-molybdenum catalyst: grinding 0.8g of a precursor of the iron-molybdenum catalyst and 0.4g of LiH to uniformly mix, quickly transferring the mixture into a quartz bubble which is easy to store, slowly heating to 450 ℃ in a vacuum state, keeping the temperature for 2 hours, wherein the heating rate is 1 ℃/min, sealing after cooling to room temperature, slowly injecting 5mL of deionized water into the quartz bubble under the condition of ice-water bath until the reaction is completed, transferring the mixture into 300mL of deionized water, and carrying out ultrasonic treatment for 8 minutes; washing with deionized water for three times, and vacuum drying to obtain Li-Fe-MoO as lithium-doped two-dimensional iron-molybdenum catalyst2；
(3) Mixing 30mg of lithium-doped two-dimensional iron-molybdenum catalyst and 0.5g of quartz sand of 140 meshes uniformly in a glove box, filling the mixture into a quartz reaction tube (the inner diameter is 6mm), sealing, transferring the quartz reaction tube to a fixed bed reactor, and adopting N with the molar ratio of 1:32And H2The mixed gas is used as reaction gas, the flow rate is 60mL/min, and the pressure is kept at 1 Mpa; after the gas flow is stable, heating to 400 ℃ for reaction for 3h (the heating rate is 4 ℃/min), thereby completing the thermocatalytic synthesis of ammonia; final tail gas consumption of 0.25mM H2SO4Absorbing the solution, taking 1mL of tail gas absorption liquid to measure NH in the ion chromatogram4 +The peak area of (A) is substituted into the regression curve equation of FIG. 8 to obtain NH of the tail gas absorption liquid4 +The concentration is calculated, and the generation amount of ammonia gas can reach 3007.11umol g-1*h-1。
Example 4
Preparation of acid-treated lithium-doped two-dimensional iron molybdenum catalyst (designated as H)+-Li-Fe-MoO2) And their catalysis of N2、H2Synthesis of NH3。
(1) Preparing an iron-molybdenum catalyst precursor: same as example 1;
(2) preparation of acid-treated lithium-doped two-dimensional iron-molybdenum catalyst: grinding 0.8g of precursor of the iron-molybdenum catalyst and 0.4g of LiH to uniformly mix, quickly transferring the mixture into a quartz bubble which is easy to store, slowly heating to 450 ℃ in a vacuum state, keeping the temperature for 2 hours, wherein the heating rate is 1 ℃/min, sealing after cooling to room temperature, slowly injecting 5mL of deionized water into the quartz bubble under the condition of ice-water bath until the reaction is completed, and transferring the mixture into concentrated hydrochloric acid containing 6mL (the density is 1.179 g/cm)3) In 300mL of deionized water, and carrying out ultrasonic treatment for 8 min; washing for three times by using deionized water, and then drying in vacuum to obtain the acid-treated lithium-doped two-dimensional iron-molybdenum catalyst H+-Li-Fe-MoO2；
(3) Mixing 30mg of acid-treated lithium-doped two-dimensional iron-molybdenum catalyst and 0.5g of 140-mesh quartz sand uniformly in a glove box, filling the mixture into a quartz reaction tube (the inner diameter is 6mm), sealing, transferring the quartz reaction tube to a fixed bed reactor, and adopting N with the molar ratio of 1:32And H2The mixed gas is used as reaction gas, the flow rate is 60mL/min, and the pressure is kept at 1 Mpa; after the gas flow is stable, heating to 400 ℃ for reaction for 3h (the heating rate is 4 ℃/min), thereby completing the thermocatalytic synthesis of ammonia; final tail gas consumption of 0.25mM H2SO4Absorbing the solution, taking 1mL of tail gas absorption liquid to measure NH in the ion chromatogram4 +The peak area of (A) is substituted into the regression curve equation of FIG. 8 to obtain NH of the tail gas absorption liquid4 +Concentration, and calculating the amount of ammonia gas generated, wherein the amount of ammonia gas generated can be3207.61umol g is achieved-1*h-1。
Example 5
Preparation of molybdenum dioxide catalyst (named MoO)2) And their catalysis of N2、H2Synthesis of NH3。
(1) Preparing a molybdenum dioxide catalyst precursor: the catalyst MoO was obtained in the same manner as in example 22；
(2) Mixing 30mg of molybdenum dioxide catalyst precursor and 0.5g of quartz sand with 140 meshes uniformly in a glove box, filling the mixture into a quartz reaction tube (the inner diameter is 6mm), sealing, transferring the quartz reaction tube to a fixed bed reactor, and adopting N with the molar ratio of 1:32And H2The mixed gas is used as reaction gas, the flow rate is 60mL/min, and the pressure is kept at 1 Mpa; after the gas flow is stable, heating to 400 ℃ for reaction for 3h (the heating rate is 4 ℃/min), thereby completing the thermocatalytic synthesis of ammonia; final tail gas consumption of 0.25mM H2SO4Absorbing the solution, taking 1mL of tail gas absorption liquid to measure NH in the ion chromatogram4 +The peak area of (A) is substituted into the regression curve equation of FIG. 8 to obtain NH of the tail gas absorption liquid4 +The concentration is calculated, and the generation amount of ammonia gas can reach 62.49umol g-1*h-1。
Example 6
Traditional catalyst-ruthenium cesium-loaded modified magnesium oxide (named as Ru-Cs-MgO) and catalytic N thereof2、H2Synthesis of NH3。
(1) Preparation of ruthenium-loaded magnesium oxide precursor: weighing 1.5g MgO, grinding, transferring into quartz boat, placing into vacuum tube furnace, calcining at 500 deg.C for 6 hr, and placing into a furnace containing 0.0314g Ru3(CO)12In tetrahydrofuran solution under an inert atmosphere (N)2Or Ar) stirring and dipping for 5h, evaporating to dryness by rotation, and then drying in vacuum to obtain a precursor Ru3(CO)12-MgO；
(2) 1.0g of Ru3(CO)12Transferring MgO into quartz bulb easy to be sealed, slowly heating to 450 deg.C under vacuum condition for 2 hr at heating rate of 1 deg.C/min, sealing after cooling to room temperature, and filling inert gas (N)2Or Ar) is rapidly transferred to Cs2CO3Evaporating the ethanol solution in a rotary manner to dryness and then drying in vacuum to obtain a catalyst Ru-Cs MgO;
(3) mixing 30mg Ru-Cs-MgO catalyst and 0.5g quartz sand of 140 meshes uniformly in a glove box, loading the mixture into a quartz reaction tube (the inner diameter is 6mm), sealing, transferring the quartz reaction tube to a fixed bed reactor, and adopting N with the molar ratio of 1:32And H2The mixed gas is used as reaction gas, the flow rate is 60mL/min, and the pressure is kept at 1 Mpa; after the gas flow is stable, heating to 400 ℃ for reaction for 3h (the heating rate is 4 ℃/min), thereby completing the thermocatalytic synthesis of ammonia; absorbing the final tail gas with 0.25mM H2SO4 solution, and taking 1mL tail gas absorption solution to measure NH in ion chromatography4 +The peak area of (A) is substituted into the regression curve equation of FIG. 8 to obtain NH of the tail gas absorption liquid4 +The concentration is calculated, and the generation amount of ammonia gas can reach 828.88umol g-1*h-1。
Example 7
Preparation of iron-supported magnesium oxide catalyst (named Li-Fe-MgO) and its catalytic N2、H2Synthesis of NH3。
(1) Preparing an iron-loaded magnesium oxide precursor: weighing 1g of MgO, grinding, transferring into a quartz boat, placing into a vacuum tube furnace, calcining at 500 ℃ for 6h, and placing into 14.48ml of FeCl3In 0.5g/L of ethanol under an inert atmosphere (N)2Or Ar) stirring and dipping for 5h, then carrying out rotary evaporation and evaporation to dryness, and then carrying out vacuum drying to obtain an iron-molybdenum catalyst precursor Fe-MgO; (ii) a
(2) Preparation of iron-supported magnesium oxide catalyst: grinding 0.8g of iron-loaded magnesium oxide precursor and 0.4g of LiH to achieve uniform mixing, quickly transferring into a quartz bubble which is easy to store, slowly heating to 450 ℃ in a vacuum state, keeping for 2h, wherein the heating rate is 1 ℃/min, sealing after cooling to room temperature, slowly injecting 5mL of deionized water into the quartz bubble under the condition of ice water bath until the reaction is completed, transferring into 300mL of deionized water, and carrying out ultrasonic treatment for 8 min; washing with deionized water for three times, and vacuum drying to obtain iron-loaded magnesium oxide catalyst Li-Fe-MgO;
(3) 30mg of iron was loaded with oxygenMixing magnesium oxide catalyst and 0.5g of 140-mesh quartz sand uniformly in a glove box, loading into a quartz reaction tube (the inner diameter is 6mm), sealing, transferring to a fixed bed reactor, and adopting N with the molar ratio of 1:32And H2The mixed gas is used as reaction gas, the flow rate is 60mL/min, and the pressure is kept at 1 Mpa; after the gas flow is stable, heating to 400 ℃ for reaction for 3h (the heating rate is 4 ℃/min), thereby completing the thermocatalytic synthesis of ammonia; final tail gas consumption of 0.25mM H2SO4Absorbing the solution, taking 1mL of tail gas absorption liquid to measure NH in the ion chromatogram4 +The peak area of (A) is substituted into the regression curve equation of FIG. 8 to obtain NH of the tail gas absorption liquid4 +The concentration is calculated, and the generation amount of ammonia gas can reach 26.00umol g-1*h-1。
Example 8
Preparation of calcium-doped two-dimensional iron-molybdenum catalyst (named Ca-Fe-MoO)2) And their catalysis of N2、H2Synthesis of NH3。
(1) Preparing an iron-molybdenum catalyst precursor: same as example 1;
(2) preparing a calcium-doped two-dimensional iron-molybdenum catalyst: 0.8g of precursor of the iron-molybdenum catalyst and 2.1328g of CaH are taken2Grinding to achieve uniform mixing, quickly transferring into a quartz bubble which is easy to store, slowly heating to 450 ℃ in a vacuum state, keeping for 2h, heating at the rate of 1 ℃/min, sealing after cooling to room temperature, slowly injecting 5mL of deionized water into the quartz bubble under the condition of ice-water bath, transferring into 300mL of deionized water after complete reaction, and carrying out ultrasonic treatment for 8 min; washing with deionized water for three times, and vacuum drying to obtain Ca-Fe-MoO as Ca-doped two-dimensional iron-molybdenum catalyst2；
(3) Mixing 30mg of calcium-doped two-dimensional iron-molybdenum catalyst and 0.5g of 140-mesh quartz sand uniformly in a glove box, filling the mixture into a quartz reaction tube (the inner diameter is 6mm), sealing, transferring the quartz reaction tube to a fixed bed reactor, and adopting N with the molar ratio of 1:32And H2The mixed gas is used as reaction gas, the flow rate is 60mL/min, and the pressure is kept at 1 Mpa; after the gas flow is stable, heating to 400 ℃ for reaction for 3h (the heating rate is 4 ℃/min), thereby completing the thermocatalytic synthesis of ammonia; finally, the0.25mM of H for the tail gas2SO4Absorbing the solution, taking 1mL of tail gas absorption liquid to measure NH in the ion chromatogram4 +The peak area of (A) is substituted into the regression curve equation of FIG. 8 to obtain NH of the tail gas absorption liquid4 +The concentration is calculated, and the generation amount of ammonia gas can reach 29.15umol g-1*h-1。
Example 9
Preparation of lithium-doped two-dimensional nickel-molybdenum catalyst (named Li-Ni-MoO)2) And their catalysis of N2、H2Synthesis of NH3。
(1) Preparing a nickel-molybdenum catalyst precursor: 1g of MoO was weighed2Grinding, transferring into quartz boat, calcining in vacuum tube furnace at 500 deg.C for 2 hr, and placing into 0.5g/L NiCl2In an inert atmosphere (N)2Or Ar) stirring and dipping for 5h, evaporating to dryness by rotary evaporation, and then drying in vacuum to obtain the precursor Ni-MoO of the iron-molybdenum catalyst2；
(2) Preparing a lithium-doped two-dimensional nickel-molybdenum catalyst: grinding 0.8g of a precursor of the nickel-molybdenum catalyst and 0.4g of LiH to uniformly mix, quickly transferring the mixture into a quartz bubble which is easy to store, slowly heating to 450 ℃ in a vacuum state, keeping the temperature for 2 hours, wherein the heating rate is 1 ℃/min, sealing after cooling to room temperature, slowly injecting 5mL of deionized water into the quartz bubble under the condition of ice-water bath until the reaction is completed, transferring the mixture into 300mL of deionized water, and carrying out ultrasonic treatment for 8 minutes; washing the mixture for three times by using deionized water, and then drying the mixture in vacuum to obtain the lithium-doped two-dimensional iron-molybdenum catalyst Li-Ni-MoO2；
(3) Mixing 30mg of lithium-doped two-dimensional nickel-molybdenum catalyst and 0.5g of 140-mesh quartz sand uniformly in a glove box, filling the mixture into a quartz reaction tube (the inner diameter is 6mm), sealing, transferring the quartz reaction tube to a fixed bed reactor, and adopting N with the molar ratio of 1:32And H2The mixed gas is used as reaction gas, the flow rate is 60mL/min, and the pressure is kept at 1 Mpa; after the gas flow is stable, heating to 400 ℃ for reaction for 3h (the heating rate is 4 ℃/min), thereby completing the thermocatalytic synthesis of ammonia; final tail gas consumption of 0.25mM H2SO4Absorbing the solution, taking 1mL of tail gas absorption liquid to measure in ion chromatographyNH4 +The peak area of (A) is substituted into the regression curve equation of FIG. 8 to obtain NH of the tail gas absorption liquid4 +The concentration is calculated, and the generation amount of ammonia gas can reach 1549.93umol g-1*h-1。
The above examples illustrate that lithium-doped two-dimensional iron molybdenum catalysts have significant advantages in the effect of ammonia synthesis compared to conventional catalysts and other differently doped or supported metals.
Example 10
Preparation of lithium-doped two-dimensional iron-molybdenum catalyst (named as Fe-0.5) and catalysis of N by using lithium-doped two-dimensional iron-molybdenum catalyst2、H2Synthesis of NH3。
(1) Preparing an iron-molybdenum catalyst precursor: 1g of MoO was weighed2Grinding, transferring into quartz boat, calcining in vacuum tube furnace at 500 deg.C for 2 hr, and placing in 7.24ml FeCl3In 0.5g/L of ethanol under an inert atmosphere (N)2Or Ar) stirring and dipping for 5h, evaporating to dryness by rotary evaporation, and then drying in vacuum to obtain an iron-molybdenum catalyst precursor Fe-MoO2；
(2) Preparing a lithium-doped two-dimensional iron-molybdenum catalyst: same as example 3, record as Fe-0.5;
(3) mixing 30mg of lithium-doped two-dimensional iron-molybdenum catalyst and 0.5g of quartz sand of 140 meshes uniformly in a glove box, filling the mixture into a quartz reaction tube (the inner diameter is 6mm), sealing, transferring the quartz reaction tube to a fixed bed reactor, and adopting N with the molar ratio of 1:32And H2The mixed gas is used as reaction gas, the flow rate is 60mL/min, and the pressure is kept at 1 Mpa; after the gas flow is stable, heating to 400 ℃ for reaction for 3h (the heating rate is 4 ℃/min), thereby completing the thermocatalytic synthesis of ammonia; final tail gas consumption of 0.25mM H2SO4Absorbing the solution, taking 1mL of tail gas absorption liquid to measure NH in the ion chromatogram4 +The peak area of (A) is substituted into the regression curve equation of FIG. 8 to obtain NH of the tail gas absorption liquid4 +The concentration is calculated, and the generation amount of ammonia gas can reach 1083.17umol g-1*h-1。
Example 11
Lithium-doped two-dimensional iron-molybdenum catalystPreparation of the Agents (named Fe-3) and their catalysis of N2、H2Synthesis of NH3。
(1) Preparing an iron-molybdenum catalyst precursor: 1g of MoO was weighed2Grinding, transferring into quartz boat, calcining in vacuum tube furnace at 500 deg.C for 2 hr, and placing into 43.44ml FeCl3In 0.5g/L of ethanol under an inert atmosphere (N)2Or Ar) stirring and dipping for 5h, evaporating to dryness by rotary evaporation, and then drying in vacuum to obtain an iron-molybdenum catalyst precursor Fe-MoO2；
(2) Preparing a lithium-doped two-dimensional iron-molybdenum catalyst: same as example 3, noted as Fe-3;
(3) mixing 30mg of lithium-doped two-dimensional iron-molybdenum catalyst and 0.5g of quartz sand of 140 meshes uniformly in a glove box, filling the mixture into a quartz reaction tube (the inner diameter is 6mm), sealing, transferring the quartz reaction tube to a fixed bed reactor, and adopting N with the molar ratio of 1:32And H2The mixed gas is used as reaction gas, the flow rate is 60mL/min, and the pressure is kept at 1 Mpa; after the gas flow is stable, heating to 400 ℃ for reaction for 3h (the heating rate is 4 ℃/min), thereby completing the thermocatalytic synthesis of ammonia; final tail gas consumption of 0.25mM H2SO4Absorbing the solution, taking 1mL of tail gas absorption liquid to measure NH in the ion chromatogram4 +The peak area of (A) is substituted into the regression curve equation of FIG. 8 to obtain NH of the tail gas absorption liquid4 +The concentration is calculated, and the generation amount of ammonia gas can reach 2140.59umol g-1*h-1。
Example 12
Preparation of lithium-doped two-dimensional iron-molybdenum catalyst (named as Fe-5) and N catalysis thereof2、H2Synthesis of NH3。
(1) Preparing an iron-molybdenum catalyst precursor: 1g of MoO was weighed2Grinding, transferring into quartz boat, calcining in vacuum tube furnace at 500 deg.C for 2 hr, and placing into 72.4ml FeCl3In 0.5g/L of ethanol under an inert atmosphere (N)2Or Ar) stirring and dipping for 5h, evaporating to dryness by rotary evaporation, and then drying in vacuum to obtain an iron-molybdenum catalyst precursor Fe-MoO2；
(2) Preparing a lithium-doped two-dimensional iron-molybdenum catalyst: same as example 3, noted as Fe-5;
(3) mixing 30mg of lithium-doped two-dimensional iron-molybdenum catalyst and 0.5g of quartz sand of 140 meshes uniformly in a glove box, filling the mixture into a quartz reaction tube (the inner diameter is 6mm), sealing, transferring the quartz reaction tube to a fixed bed reactor, and adopting N with the molar ratio of 1:32And H2The mixed gas is used as reaction gas, the flow rate is 60mL/min, and the pressure is kept at 1 Mpa; after the gas flow is stable, heating to 400 ℃ for reaction for 3h (the heating rate is 4 ℃/min), thereby completing the thermocatalytic synthesis of ammonia; final tail gas consumption of 0.25mM H2SO4Absorbing the solution, taking 1mL of tail gas absorption liquid to measure NH in the ion chromatogram4 +The peak area of (A) is substituted into the regression curve equation of FIG. 8 to obtain NH of the tail gas absorption liquid4 +The concentration is calculated, and the generation amount of ammonia gas can reach 1763.99umol g-1*h-1。
Example 13
Preparation of lithium-doped two-dimensional iron-molybdenum catalyst (named Li-Fe-MoO)2) And their catalysis of N2、H2Synthesis of NH3。
(1) Preparing an iron-molybdenum catalyst precursor: same as example 1;
(2) preparing a lithium-doped two-dimensional iron-molybdenum catalyst: same as in example 3;
(3) mixing 30mg of lithium-doped two-dimensional iron-molybdenum catalyst and 0.5g of quartz sand of 140 meshes uniformly in a glove box, filling the mixture into a quartz reaction tube (the inner diameter is 6mm), sealing, transferring the quartz reaction tube to a fixed bed reactor, and adopting N with the molar ratio of 1:32And H2The mixed gas is used as reaction gas, the flow rate is 60mL/min, and the pressure is kept at 1 Mpa; after the gas flow is stable, heating to 400 ℃ for reaction for 1h, 3h, 5h, 10h, 15h, 20h, 25h, 30h, 35h, 40h, 45h and 50h (the heating rate is 4 ℃/min), thereby completing the thermocatalytic synthesis of ammonia; final tail gas consumption of 0.25mM H2SO4Absorbing the solution, taking 1mL of tail gas absorption liquid to measure NH in the ion chromatogram4 +The peak area of (A) is substituted into the regression curve equation of FIG. 8 to obtain NH of the tail gas absorption liquid4 +Concentration and calculating the amount of ammonia gas producedThe ammonia gas can reach 2723.08umol g-1*h-1，3007.11umol*g-1*h-1， 1951.9umol*g-1*h-1，2486.61umol*g-1*h-1，2465.94umol*g-1*h-1，2475.7umol*g-1*h-1， 2309.37umol*g-1*h-1，2309.3umol*g-1*h-1，2335.08umol*g-1*h-1，2480.92umol*g-1*h-1， 2655.71umol*g-1*h-1，2525.77umol*g-1*h-1。
Example 14
Preparation of lithium-doped two-dimensional iron-molybdenum catalyst (named Li-Fe-MoO)2) And their catalysis of N2、H2Synthesis of NH3。
(1) Preparing an iron-molybdenum catalyst precursor: same as example 1;
(2) preparing a lithium-doped two-dimensional iron-molybdenum catalyst: same as in example 3;
(3) mixing 30mg of lithium-doped two-dimensional iron-molybdenum catalyst and 0.5g of quartz sand of 140 meshes uniformly in a glove box, filling the mixture into a quartz reaction tube (the inner diameter is 6mm), sealing, transferring the quartz reaction tube to a fixed bed reactor, and adopting N with the molar ratio of 1:32And H2The mixed gas is used as reaction gas, the flow rate is 60mL/min, and the pressure is kept at 1 Mpa; after the gas flow is stable, heating to 350 ℃ for reaction for 3h (the heating rate is 4 ℃/min), thereby completing the thermocatalytic synthesis of ammonia; final tail gas consumption of 0.25mM H2SO4Absorbing the solution, taking 1mL of tail gas absorption liquid to measure NH in the ion chromatogram4 +The peak area of (A) is substituted into the regression curve equation of FIG. 8 to obtain NH of the tail gas absorption liquid4 +The concentration is calculated, and the generation amount of ammonia gas can reach 779.06umol g-1*h-1。
Example 15
Preparation of lithium-doped two-dimensional iron-molybdenum catalyst (named Li-Fe-MoO)2) And their catalysis of N2、H2Synthesis of NH3。
(1) Preparing an iron-molybdenum catalyst precursor: same as example 1;
(2) preparing a lithium-doped two-dimensional iron-molybdenum catalyst: same as in example 3;
(3) mixing 30mg of lithium-doped two-dimensional iron-molybdenum catalyst and 0.5g of quartz sand of 140 meshes uniformly in a glove box, filling the mixture into a quartz reaction tube (the inner diameter is 6mm), sealing, transferring the quartz reaction tube to a fixed bed reactor, and adopting N with the molar ratio of 1:32And H2The mixed gas is used as reaction gas, the flow rate is 60mL/min, and the pressure is kept at 1 Mpa; after the gas flow is stable, heating to 375 ℃ and reacting for 3h (the heating rate is 4 ℃/min), thereby completing the thermal catalytic synthesis of ammonia; final tail gas consumption of 0.25mM H2SO4Absorbing the solution, taking 1mL of tail gas absorption liquid to measure NH in the ion chromatogram4 +The peak area of (A) is substituted into the regression curve equation of FIG. 8 to obtain NH of the tail gas absorption liquid4 +The concentration is calculated, and the generation amount of ammonia gas can reach 1603.48umol g-1*h-1。
Example 16
Preparation of lithium-doped two-dimensional iron-molybdenum catalyst (named Li-Fe-MoO)2) And their catalysis of N2、H2Synthesis of NH3。
(1) Preparing an iron-molybdenum catalyst precursor: same as example 1;
(2) preparing a lithium-doped two-dimensional iron-molybdenum catalyst: same as in example 3;
(3) mixing 30mg of lithium-doped two-dimensional iron-molybdenum catalyst and 0.5g of quartz sand of 140 meshes uniformly in a glove box, filling the mixture into a quartz reaction tube (the inner diameter is 6mm), sealing, transferring the quartz reaction tube to a fixed bed reactor, and adopting N with the molar ratio of 1:32And H2The mixed gas is used as reaction gas, the flow rate is 60mL/min, and the pressure is kept at 1 Mpa; after the gas flow is stable, heating to 425 ℃ and reacting for 3h (the heating rate is 4 ℃/min), thereby completing the thermocatalytic synthesis of ammonia; final tail gas consumption of 0.25mM H2SO4Absorbing the solution, taking 1mL of tail gas absorption liquid to measure NH in the ion chromatogram4 +The peak area of (A) is substituted into the regression curve equation of FIG. 8 to obtain NH of the tail gas absorption liquid4 +The concentration is calculated, and the generation amount of ammonia gas can reach 4108.97umol g-1*h-1。
Example 17
Preparation of lithium-doped two-dimensional iron-molybdenum catalyst (named Li-Fe-MoO)2) And their catalysis of N2、H2Synthesis of NH3。
(1) Preparing an iron-molybdenum catalyst precursor: same as example 1;
(2) preparing a lithium-doped two-dimensional iron-molybdenum catalyst: same as in example 3;
(3) mixing 30mg of lithium-doped two-dimensional iron-molybdenum catalyst and 0.5g of quartz sand of 140 meshes uniformly in a glove box, filling the mixture into a quartz reaction tube (the inner diameter is 6mm), sealing, transferring the quartz reaction tube to a fixed bed reactor, and adopting N with the molar ratio of 1:32And H2The mixed gas is used as reaction gas, the flow rate is 60mL/min, and the pressure is kept at 1 Mpa; after the gas flow is stable, heating to 425 ℃ and reacting for 3h (the heating rate is 4 ℃/min), thereby completing the thermocatalytic synthesis of ammonia; final tail gas consumption of 0.25mM H2SO4Absorbing the solution, taking 1mL of tail gas absorption liquid to measure NH in the ion chromatogram4 +The peak area of (A) is substituted into the regression curve equation of FIG. 8 to obtain NH of the tail gas absorption liquid4 +The concentration is calculated, and the generation amount of ammonia gas can reach 6068.27umol g-1*h-1。

Claims (7)

1. A preparation method of a lithium-doped two-dimensional iron-molybdenum catalyst for synthesizing ammonia gas by thermally catalyzing nitrogen and hydrogen with a mobile phase comprises the following steps:
(1) preparing an iron-molybdenum catalyst precursor: adding 0.4-5 g of MoO2Calcining the ground mixture for 1 to 5 hours at 300 to 800 ℃ in vacuum, and then placing the calcined mixture in 0.1 to 2g/L of organic solvent solution of iron salt in inert atmosphere (N)2Or Ar) stirring and dipping for 3-10 h, and performing rotary evaporation and evaporation to dryness and then vacuum drying to obtain an iron-molybdenum catalyst precursor;
(2) preparing a lithium-doped two-dimensional iron-molybdenum catalyst: mixing the iron-molybdenum catalyst precursor obtained in the step (1) with lithium salt in a molar ratio of 1: 5-13, grinding and uniformly mixing, slowly heating to 200-600 ℃ in a vacuum state, keeping for 1-10 h, cooling to room temperature, and sealing; slowly injecting a little deionized water into the reaction system under the ice-water bath condition to immerse the reaction product, transferring the reaction product into 50-1000 mL of deionized water containing 0-10 mL of concentrated hydrochloric acid after the reaction is completed, and carrying out ultrasonic treatment for 2-10 min; and washing the reaction product with deionized water for 3-5 times, and then drying in vacuum to obtain the lithium-doped two-dimensional iron-molybdenum catalyst for synthesizing ammonia gas by using the mobile phase thermal catalysis nitrogen and hydrogen.
2. The preparation method of the lithium-doped two-dimensional iron-molybdenum catalyst for synthesizing ammonia gas by thermally catalyzing nitrogen and hydrogen with the mobile phase according to claim 1, which is characterized by comprising the following steps: in the step (1), the organic solvent solution of ferric salt is FeCl3Ethanol solution of (3), Fe2(SO4)3Ethanol solution of (3), Fe3(CO)12THF solution of (1), Fe2(CO)9THF solution of (1), FeC4H7O5·nH2Ethanol solution of O, FePO4Ethanol solution of (3), Fe2(C2O4)3Ethanol solution of (2), FeSO4Ethanol solution of (3), Fe3(PO4)2·nH2Ethanol solution of O, FeBr3Ethanol solution of (D), FeCl2Ethanol solution of (5) FeBr2And (3) one of the ethanol solutions of (1).
3. The preparation method of the lithium-doped two-dimensional iron-molybdenum catalyst for synthesizing ammonia gas by thermally catalyzing nitrogen and hydrogen with the mobile phase according to claim 1, which is characterized by comprising the following steps: in the step (2), the temperature is slowly raised to 200-600 ℃ in a vacuum state at a heating rate of 0.2-2 ℃/min.
4. The preparation method of the lithium-doped two-dimensional iron-molybdenum catalyst for synthesizing ammonia gas by thermally catalyzing nitrogen and hydrogen with the mobile phase according to claim 1, which is characterized by comprising the following steps: the lithium salt is LiH or C4H9Li、LiAlH4、LiBH4One kind of (1).
5. A lithium-doped two-dimensional iron-molybdenum catalyst for synthesizing ammonia gas by thermally catalyzing nitrogen and hydrogen with a mobile phase is characterized in that: is prepared by the method of any one of claims 1 to 4.
6. The application of the lithium-doped two-dimensional iron-molybdenum catalyst for synthesizing ammonia gas by thermally catalyzing nitrogen and hydrogen with the mobile phase according to claim 5 in the thermal catalysis synthesis of ammonia.
7. The application of the lithium-doped two-dimensional iron-molybdenum catalyst for synthesizing ammonia gas by thermally catalyzing nitrogen and hydrogen with a mobile phase in the thermal catalysis of ammonia synthesis according to claim 6, wherein the lithium-doped two-dimensional iron-molybdenum catalyst comprises the following components in percentage by weight: 0.1-1 g of lithium-doped two-dimensional iron-molybdenum catalyst is pressed into tablets under 2-30 MPa for 1-30 min, and the pressed tablets are taken out, smashed and sieved; selecting 20-60-mesh catalyst particles, filling the catalyst particles into a quartz reaction tube with the inner diameter of 4-8 mm in a glove box, wherein the filling height of the catalyst is 2-3 times of the inner diameter, and transferring the quartz reaction tube to a fixed bed reactor after sealing; or 0.01-1 g of catalyst and 0.4-1.0 g of quartz sand of 20-140 meshes are uniformly mixed in a glove box, filled into a quartz reaction tube and sealed, and then transferred to a fixed bed reactor; the method comprises the following steps of: 3 is N2And H2The mixed gas is reaction gas, the flow rate is 5-100 mL/min, and the pressure is kept at 0.1-4 MPa; after the airflow is stable, the temperature is raised to 50-800 ℃ for catalytic reaction for 1-120 h, and the temperature raising rate is 3-5 ℃/min, so that the thermal catalytic synthesis of ammonia is completed.
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