Porous catalyst for preparing green ammonia as well as preparation method and application of porous catalyst

Abstract

The invention discloses a porous catalyst for preparing green ammonia and a preparation method and application thereof, the porous catalyst for preparing green ammonia comprises the following raw material components: 50-70% of austenite iron powder, 15-20% of silica gel and the balance of an auxiliary agent, and the auxiliary agent is a mixture of kaolin, calcium carbonate powder and diatomite. According to the porous catalyst for preparing the green ammonia, the green ammonia synthesis temperature and pressure are reduced, and the ammonia synthesis rate is increased; the catalyst is high in structural strength, good in stability, slow in attenuation, long in service life and capable of being continuously and stably used for a long time, the replacement frequency of the catalyst is reduced, and the production cost is reduced; the method is suitable for industrialization.

Description

Technical Field

[0001] The invention relates to a porous catalyst for preparing green ammonia, a preparation method and application thereof, belonging to the technical field of electrolyzing hydrated ammonia using wind energy or solar energy, and belonging to the technical field of wind energy industry or solar energy industry. Background Art

[0002] The production process of green ammonia mainly relies on renewable energy (such as wind power, solar energy, hydropower, etc.), electrolyzing water to produce green hydrogen, which is then catalytically synthesized with nitrogen to form ammonia. Specifically, green power is obtained through renewable energy (wind power, solar energy, etc.) and used to produce hydrogen and nitrogen. The produced hydrogen and nitrogen are compressed to a certain pressure by a compressor and then enter the ammonia synthesis system. The reaction of synthesizing ammonia is completed under high temperature and high pressure.

[0003] The production process of green ammonia does not rely on fossil energy. It is essentially a zero-carbon fuel that only produces nitrogen and water after combustion, but no carbon dioxide. Ammonia has high volumetric energy density and is easy to liquefy, making it easier to store and transport than hydrogen. Ammonia can be transported in a variety of ways, such as pipelines and ships. In particular, as a carrier for the storage and transportation of hydrogen, it can achieve low-cost ocean transportation of hydrogen. At the same time, ammonia is also an important chemical raw material and can be used in the production and preparation of fertilizers, etc.

[0004] The reaction pressure of green ammonia in the prior art is about 35MPa and the temperature is 500-600℃. There are also individual reports that low-temperature and low-pressure synthesis of green ammonia can be achieved through the selection and improvement of catalysts, but the rate of synthetic ammonia is low, at about 50-600μmol / (gh), which is not conducive to industrial production. At the same time, the existing synthesis of ammonia catalyst preparation process is complicated, and a large amount of precious metals are required in the preparation process, resulting in high catalyst costs, which is not conducive to industrial promotion. Summary of the invention

[0005] The present invention provides a porous catalyst for preparing green ammonia, a preparation method thereof and an application thereof. The porous catalyst for preparing green ammonia of the present invention has the advantages of fast ammonia production rate, simple preparation, low cost, high structural strength, long service life and the like, and is conducive to industrial promotion.

[0006] In order to solve the above technical problems, the technical solutions adopted by the present invention are as follows:

[0007] A porous catalyst for preparing green ammonia, the raw material components of which include: 50-70% austenite iron powder, 15-20% silica gel, and the balance of auxiliary agent, wherein the auxiliary agent is a mixture of kaolin, calcium carbonate powder and diatomaceous earth.

[0008] The porous catalyst has a simple raw material composition and can be used repeatedly for a long time.

[0009] The inventors have found in practice that different additives affect the structural morphology and comparative surface area of ​​the porous catalyst, and also affect the dispersion of the metal component to a certain extent. After repeated tests, different additives have a greater impact on the rate of ammonia synthesis in the present application. Preferably, the additive is a mixture of kaolin, calcium carbonate powder and diatomaceous earth in a mass ratio of 1: (0.2-0.5): (1-1.2).

[0010] The austenitic iron used in the present application can be ground from austenitic iron, or directly purchased from the market.

[0011] In order to take both dispersibility and processability into consideration, the fineness of the austenitic iron powder is 100-300 meshes.

[0012] In order to further improve the catalytic effect of the porous catalyst used for preparing green ammonia, the raw material components also include: 0.3-0.6% beryllium powder.

[0013] In order to further improve the catalytic effect of the porous catalyst used for preparing green ammonia, the raw material components also include: 0.1-0.3% scandium powder.

[0014] The fineness of the beryllium powder and scandium powder is 250-350 mesh.

[0015] The invention found that the addition of beryllium and scandium promoted the dispersion and refinement of the porous catalyst, obtained a porous catalyst with ultrafine nanopore size, and promoted a significant improvement in the catalytic effect; at the same time, it also promoted the improvement of the strength of the porous catalyst, reduced loss, and extended the service life.

[0016] The preparation method of the porous catalyst for green ammonia preparation is as follows: austenitic iron powder, silica gel and additives are mixed evenly, extruded into granules, heated to 800-1000°C at a rate of 6-8°C / min under nitrogen protection, calcined for 8-10 hours, and naturally cooled to room temperature to obtain a porous catalyst.

[0017] If the raw material components also include: beryllium powder and / or scandium powder, first mix the austenitic iron powder, beryllium powder and / or scandium powder, and the additives, then add silica gel and mix, extrude and granulate, then heat to 800-1000°C at a rate of 6-8°C / min under nitrogen protection, calcine at this temperature for 8-10 hours, and cool naturally to room temperature to obtain a porous catalyst.

[0018] The raw materials not specifically described in this application were of analytical grade AR.

[0019] The porous catalyst obtained by the above method has high strength and good stability and can be used continuously for more than 3 years.

[0020] The porous catalyst for preparing green ammonia is used to catalyze hydrogen and nitrogen to synthesize ammonia; the reaction temperature is 300-350° C. and the pressure is 1-7 MPa.

[0021] The technologies not mentioned in the present invention are all referred to the prior art.

[0022] The porous catalyst used for preparing green ammonia of the present invention reduces the temperature and pressure of green ammonia synthesis and improves the rate of synthesizing ammonia; the catalyst has high structural strength, good stability, slow decay, long service life, can be used continuously and stably for a long time, reduces the number of times the catalyst is replaced, and reduces the production cost; and is suitable for industrialization. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural schematic diagram of a green ammonia synthesis tower;

[0024] Figure 2 It is a structural schematic diagram of a green ammonia preparation system;

[0025] In the figure, 1 is a synthesis tower, 101 is a gas distribution pipe, 102 is a gas collecting pipe, 103 is a first cooling pipe, 104 is a second cooling pipe, 105 is a temperature equalizing pipe, 106 is an inner tube, 107 is a preheater, 108 is an air inlet main pipe, 109 is a central heating pipe, 110 is a transition pipe; 111 is a temperature measuring device, 112 is a primary cold air inlet, 113 is a secondary cold air inlet, 114 is a discharge port, and 115 is a waste discharge port; 2 is a nitrogen and hydrogen storage tank, 3 is a first delivery port, delivery pipe, 4 is the second delivery pipe, 5 is the first heat exchanger, 6 is the third delivery pipe, 7 is the second heat exchanger, 8 is the fourth delivery pipe, 9 is the ammonia separator, 10 is the fifth delivery pipe, 11 is the liquid ammonia storage tank, 12 is the sixth delivery pipe, 13 is the synthesis cycle compressor, 14 is the seventh delivery pipe, 15 is the eighth delivery pipe, 16 is the electrolytic hydrogen production device, 17 is the hydrogen purification device, 18 is the nitrogen production device, 19 is the high-pressure unit, 20 is the delivery pump, and a is the finished liquid ammonia. DETAILED DESCRIPTION

[0026] In order to better understand the present invention, the content of the present invention is further explained below in conjunction with the embodiments, but the content of the present invention is not limited to the following embodiments.

[0027] Example 1

[0028] like Figure 2 As shown, a green ammonia preparation system includes an electrolytic hydrogen production device, a hydrogen purification device, a nitrogen production device, a high-pressure unit, a nitrogen-hydrogen storage tank, a first delivery pipe, a synthesis tower, a second delivery pipe, a first heat exchanger, a third delivery pipe, a second heat exchanger, a fourth delivery pipe, an ammonia separator, a fifth delivery pipe, a liquid ammonia storage tank, a sixth delivery pipe and a synthesis cycle compressor, a seventh delivery pipe and an eighth delivery pipe;

[0029] The hydrogen outlet of the electrolytic hydrogen production device is connected to the air inlet of the hydrogen purification device through a pipeline, and the air outlet of the hydrogen purification device is connected to the air inlet of the high-pressure unit through a pipeline; the nitrogen outlet of the nitrogen production device is connected to the air inlet of the high-pressure unit through a pipeline; the air outlet of the high-pressure unit is connected to the nitrogen and hydrogen storage tank through a pipeline; the electric energy required by the electrolytic hydrogen production device is provided by the photovoltaic power generation device and the wind power generation device;

[0030] like Figure 1 As shown, the synthesis tower includes a synthesis tower body, an inner tube, an air distribution pipe, an air collecting pipe, a first cooling pipe, a second cooling pipe, a temperature equalizing pipe, a preheater, an air intake main pipe, a central heating pipe and a transition pipe;

[0031] The inner tube is located inside the synthesis tower body, and a gap is left between the inner tube and the synthesis tower body to form a sandwich structure, and the top of the sandwich structure is connected with the top of the inner tube;

[0032] The gas distribution pipe, gas collecting pipe, first cooling pipe, second cooling pipe, temperature equalizing pipe, preheater, central heating pipe and transition pipe are all located inside the inner tube;

[0033] The gas distribution pipe and the gas collection pipe are both annular pipes. The gas distribution pipe is located directly above the gas collection pipe. A porous catalyst layer is arranged between the gas distribution pipe and the gas collection pipe. In order to facilitate the internal structure, the porous catalyst layer is omitted in the figure.

[0034] The first cooling tube, the second cooling tube and the equalizing tube are all located in the porous catalyst layer between the gas distribution tube and the gas collection tube; the lengths of the first cooling tube and the second cooling tube are both less than the interval between the gas distribution tube and the gas collection tube, the first cooling tube and the second cooling tube are arranged alternately, the top of the first cooling tube is connected to the gas distribution tube, the bottom of the second cooling tube is connected to the gas collection tube, and air holes are distributed on the side walls of the first cooling tube and the second cooling tube; the length of the equalizing tube is not less than the interval between the gas distribution tube and the gas collection tube, the top of the equalizing tube is connected to the gas distribution tube, and the bottom is connected to the gas collection tube;

[0035] The preheater is located at the bottom of the gas collecting pipe, one end of the air inlet main pipe is connected to the air inlet on the preheater, and the other end passes through the bottom of the synthesis tower body, the top of the central heating pipe is connected to the air outlet on the preheater, the top passes through the porous catalyst layer, and is connected to the top of the inner tube;

[0036] A primary cold air inlet is provided at the top of the synthesis tower body, and the primary cold air inlet is connected to the air distribution pipe through a transition pipe; a secondary cold air inlet, a discharge port and a waste discharge port are provided at the bottom of the synthesis tower body, and the secondary cold air inlet is connected to the sandwich structure between the inner tube and the synthesis tower body.

[0037] When in use, the raw mixed gas (a mixture of nitrogen and hydrogen) enters from the air inlet main pipe, is preheated by the preheater, enters the central heating tube for heating, and then flows out from the top of the central heating tube, and enters the porous catalyst layer for frequent catalytic reaction. The present application is provided with a secondary cold air inlet and a primary cold air inlet at the same time, and low-temperature reaction raw gas can be input to the secondary cold air inlet and the primary cold air inlet according to the reaction needs, so as to form cooling for the inner tube and the porous catalyst layer. The low-temperature reaction raw gas entering from the secondary cold air inlet cools the side wall of the inner tube from bottom to top, and finally flows from the top of the sandwich structure into the inner tube and enters the porous catalyst layer for reaction. The low-temperature reaction raw gas entering from the primary cold air inlet enters the gas distribution pipe through the transition pipe, circulates between the gas distribution pipe, the temperature-averaging pipe and the gas collecting pipe, forms cooling for the porous catalyst layer, and when flowing through the first cooling pipe and the second cooling pipe, flows into the porous catalyst layer through the air permeable hole for reaction. Catalytic synthesis of ammonia is discharged from the discharge port at the bottom of the synthesis tower body. By setting up the primary and secondary cold air inlets, the inner cylinder and the catalyst layer can be cooled and precise temperature control can be achieved without the need to introduce additional cooling media, thereby improving energy utilization.

[0038] Temperature measuring devices are distributed at the top (T1), middle (T2), and bottom (T3) of the inner tube; a porous catalyst layer is also distributed around the preheater in the inner tube, and the porous catalyst layer in the inner tube extends from the gas distribution pipe to the bottom of the inner tube. The gas distribution pipe and the gas collection pipe have the same shape and size, and are arranged opposite to each other up and down; the length of the temperature equalizing pipe is equal to the distance between the gas distribution pipe and the gas collection pipe. Figure 2 As shown, there are 6 temperature-averaging tubes, all of which are evenly distributed between the gas distribution tube and the gas collection tube along the circumferential direction; 3 first cooling tubes and second cooling tubes are arranged alternately between every two temperature-averaging tubes, and the top of the second cooling tube is higher than the bottom of the first cooling tube. In the case of insufficient power, low-material continuous and stable operation can be achieved without being affected by weather.

[0039] One end of the first delivery pipe is connected to the nitrogen and hydrogen storage tank, and the other end is branched into a first delivery branch pipe A, a first delivery branch pipe B and a first delivery branch pipe C; the first delivery branch pipe A is connected to the inlet of the synthesis cycle compressor, and a control valve K1 is provided on the first delivery branch pipe A; the first delivery branch pipe B is connected to the secondary cold air inlet at the bottom of the synthesis tower body, and a control valve K2 is provided on the first delivery branch pipe B; the first delivery branch pipe C is connected to the primary cold air inlet at the top of the synthesis tower body, and a control valve K3 is provided on the first delivery branch pipe C;

[0040] The first heat exchanger is provided with a first hot material inlet, a first hot material outlet, a first cold material inlet and a first cold material outlet; the second heat exchanger is provided with a second hot material inlet, a second hot material outlet, a second cold material inlet and a second cold material outlet;

[0041] One end of the second delivery pipe is connected to the discharge port at the bottom of the synthesis tower body, and the other end is connected to the first hot material inlet, and a control valve K4 is provided on the second delivery pipe; one end of the third delivery pipe is connected to the first hot material outlet, and the other end is connected to the second hot material inlet, and a control valve K5 and a control valve K6 are provided on the third delivery pipe; the second cold material inlet is connected to the outlet of the cold medium supply device through the cold medium inlet pipe, and a control valve K8 is provided on the cold medium inlet pipe, and the second cold material outlet is connected to the inlet of the cold medium supply device through the cold medium outlet pipe;

[0042] One end of the fourth delivery pipe is connected to the second hot material outlet, and the other end is connected to the top feed port of the ammonia separator. A control valve K7 is provided on the fourth delivery pipe;

[0043] One end of the fifth delivery pipe is connected to the bottom discharge port of the ammonia separator, and the other end leads to the liquid ammonia storage tank. A control valve K8' is provided on the fifth delivery pipe;

[0044] One end of the sixth delivery pipe is connected to the gas outlet at the top of the ammonia separator, and the other end is connected to the inlet of the synthesis cycle compressor. The sixth delivery pipe is provided with a control valve K9 and a control valve K10;

[0045] One end of the seventh delivery pipe is connected to the outlet of the synthesis cycle compressor and the other end is connected to the first cold material inlet. The seventh delivery pipe is provided with a control valve K11. One end of the eighth delivery pipe is connected to the first cold material outlet and the other end is connected to the air intake main pipe at the bottom of the synthesis tower body. The second heat exchanger is provided with a cold source through a cold medium supply device, which is a cooling water circulation machine.

[0046] The first heat exchanger is a shell-and-tube heat exchanger; the second heat exchanger is a tube-and-tube heat exchanger; the control valve K5 is arranged on the end of the third delivery pipe connected to the first hot material outlet, and the control valve K6 is arranged on the end of the third delivery pipe connected to the second hot material inlet; the control valve K9 is arranged on the end of the sixth delivery pipe connected to the top gas outlet of the ammonia separator, and the control valve K10 is arranged on the end of the sixth delivery pipe connected to the inlet of the synthesis cycle compressor. In this example, the synthesis cycle compressor is a variable frequency device. The liquid ammonia in the liquid ammonia storage tank is transported to the target container by a delivery pump. Pump bodies, instruments and other equipment can be connected to each pipeline as needed.

[0047] The method for producing ammonia using the YHL preparation system for photovoltaic and wind power generation to produce hydrogen and synthesize green ammonia comprises the following steps:

[0048] 1) Close all control valves, open the central heating pipe on the synthesis tower body, so that the temperature inside the synthesis tower body reaches 300-350°C, and then open the control valves except control valve K2 and control valve K3;

[0049] 2) The hydrogen produced by the electrolytic hydrogen production device is purified by the hydrogen purification device, and then enters the high-pressure unit for compression with the nitrogen produced by the nitrogen production device at a ratio of 3:1.2, and the compressed nitrogen-hydrogen mixed gas enters the nitrogen-hydrogen storage tank; the nitrogen-hydrogen mixed raw material gas in the nitrogen-hydrogen storage tank passes through the first delivery branch pipe A, the synthesis cycle compressor, the seventh delivery pipe, the first heat exchanger, the eighth delivery pipe and the air intake main pipe in sequence, and then enters the preheater in the synthesis tower body, and then is heated by the central heating pipe, flows out from the top of the central heating pipe, and enters the porous catalyst layer to catalyze the reaction to generate ammonia;

[0050] 3) Ammonia flows out from the discharge port at the bottom of the synthesis tower body, enters the first heat exchanger through the second delivery pipe, is cooled by the nitrogen-hydrogen mixed raw material gas (that is, the nitrogen-hydrogen mixed raw material gas is heated by the gas flowing out from the discharge port at the bottom of the synthesis tower body), enters the second heat exchanger through the third delivery pipe for secondary cooling, and then is sent to the ammonia separator through the fourth delivery pipe to separate the unreacted nitrogen and hydrogen, and the liquid ammonia in the ammonia separator enters the liquid ammonia storage tank through the fifth delivery pipe;

[0051] 4) The unreacted nitrogen and hydrogen separated by the ammonia separator enter the synthesis cycle compressor through the sixth delivery pipe to mix with the nitrogen and hydrogen mixed raw material gas, and then enter the synthesis tower body for inner cycle reaction after passing through the seventh delivery pipe, the first heat exchanger, the eighth delivery pipe and the air inlet main pipe in sequence;

[0052] 5) During the reaction process, the opening of the control valve K2 and the control valve K3 are controlled, and the nitrogen-hydrogen mixed raw material gas directly output from the nitrogen-hydrogen storage tank is used to cool the inner tube and the porous catalyst layer, so that the temperature of the inner tube and the porous catalyst is maintained at 300°C and the pressure is maintained at 2MPa; the low-temperature reaction raw gas entering from the secondary cold air inlet cools the side wall of the inner tube from bottom to top, and finally flows from the top of the sandwich structure into the inner tube and enters the porous catalyst layer for reaction; the low-temperature reaction raw gas entering from the primary cold air inlet enters the gas distribution pipe through the transition pipe, circulates between the gas distribution pipe, the temperature equalizing pipe and the gas collecting pipe, forms cooling for the porous catalyst layer, and when flowing through the first cooling pipe and the second cooling pipe, it flows into the porous catalyst layer through the air holes for reaction;

[0053] 6) When the hydrogen production capacity of the electrolytic hydrogen production device has been or will be affected by weather, the amount of hydrogen and nitrogen entering the synthesis tower body and the amount of liquid ammonia taken out are adjusted by adjusting the opening of the control valve K4, and the temperature in the synthesis tower body is controlled to be maintained at 300℃ ( Figure 2 The temperatures of T1 / T2 / T3 are all 300°C), and the pressure is maintained at 2MPa to achieve continuous operation.

[0054] In this example, the raw material components of the porous catalyst include: 70% 200-mesh austenitic iron powder, 20% organic silica gel (Doher-711, Sains) and 10% additives, the additives are a mixture of 325-mesh kaolin, 250-mesh calcium carbonate powder and 300-mesh diatomaceous earth in a mass ratio of 1:0.3:1; the preparation method of the catalyst is: the austenitic iron powder, silica gel and additives are mixed evenly, extruded into granules (cylindrical, 5 mm in length, 5 mm in diameter), heated to 900°C at a rate of 6°C / min under nitrogen protection, calcined for 8 hours, and naturally cooled to room temperature (25°C) to obtain a porous catalyst. This catalyst has high strength, no powdering, good stability, can be used continuously for more than 3 years, and the rate of reduction of synthetic ammonia is ≤1.8% after continuous use for 6 months. In this example, the rate of synthetic ammonia is: 65mmol / (gh), the single conversion rate is more than 37%, and the cycle conversion rate reaches more than 95%.

[0055] The temperature of the nitrogen-hydrogen mixed raw material gas in the nitrogen-hydrogen storage tank is about 25°C. The nitrogen-hydrogen mixed raw material gas first passes through the synthesis cycle compressor to form a stable pressure, and then enters the synthesis tower after being heated by the product, which not only ensures the stability of operation, but also reduces energy consumption. The above method can operate continuously, stably and efficiently under the condition that the electrolytic hydrogen production device has sufficient power supply. When the electrolytic hydrogen production device has been or is about to be affected by the weather and the hydrogen production is affected, it can operate continuously and stably with low materials.

[0056] Example 2

[0057] In this example, the raw material components of the porous catalyst include: 70% 200 mesh austenitic iron powder, 0.5% 300 mesh beryllium powder (purity 98%, Shaanxi Didu New Materials Co., Ltd.), 20% organic silica gel (Doher-711, Sainz) and 9.5% additives, the additives are a mixture of 325 mesh kaolin, 250 mesh calcium carbonate powder and 300 mesh diatomaceous earth in a mass ratio of 1:0.3:1.

[0058] Preparation method of catalyst: firstly mix austenitic iron powder, beryllium powder and additives, then add silica gel and mix, extrude and granulate, heat to 900℃ at a rate of 6℃ / min under nitrogen protection, calcine for 8h, cool naturally to room temperature, and obtain a porous catalyst. The rest of the process in this example is referred to Example 1, the ammonia synthesis rate is 72mmol / (gh), the single conversion rate is more than 38%, and the cycle conversion rate reaches more than 95%. After continuous use for 6 months, the reduction rate of ammonia synthesis rate is ≤1.5%.

[0059] Example 3

[0060] In this example, the raw material components of the porous catalyst include: 70% 200 mesh austenitic iron powder, 0.2% 325 mesh scandium powder (purity 99.9%, M22-U40, Shanghai Bike New Material Technology Co., Ltd.), 20% organic silica gel (Doher-711, Sainz) and 9.8% additives, which are a mixture of 325 mesh kaolin, 250 mesh calcium carbonate powder and 300 mesh diatomaceous earth in a mass ratio of 1:0.3:1.

[0061] Preparation method of catalyst: first mix austenitic iron powder, scandium powder and additives, then add silica gel and mix, extrude and granulate, heat to 900°C at a rate of 6°C / min under nitrogen protection, calcine for 8 hours, and cool naturally to room temperature to obtain a porous catalyst. The rest of the process in this example refers to Example 1, the ammonia synthesis rate is: 83mmol / (gh), the single conversion rate is more than 37%, and the cycle conversion rate reaches more than 95%. After continuous use for 6 months, the reduction rate of ammonia synthesis rate is ≤1.2%.

[0062] Example 4

[0063] In this example, the raw material components of the porous catalyst include: 70% 200 mesh austenitic iron powder, 0.5% 300 mesh beryllium powder, 0.2% 325 mesh scandium powder, 20% organic silica gel (Doher-711, Cyanse) and 9.8% additives, and the additives are a mixture of 325 mesh kaolin, 250 mesh calcium carbonate powder and 300 mesh diatomaceous earth in a mass ratio of 1:0.3:1.

[0064] Preparation method of catalyst: firstly mix austenitic iron powder, beryllium powder, scandium powder and additives, then add silica gel and mix, extrude and granulate, heat to 900℃ at a rate of 6℃ / min under nitrogen protection, calcine for 8h, cool naturally to room temperature, and obtain a porous catalyst. The rest of the process in this example is referred to Example 1, the synthesis rate of ammonia is: 672mmol / (gh), the single conversion rate is more than 42%, and the cycle conversion rate reaches more than 98%. After continuous use for 6 months, the reduction rate of the synthesis rate of ammonia is ≤0.5%.

[0065] Comparative Example 1

[0066] The difference from Example 1 is that 200 mesh reduced iron powder is used, and the rest is the same as Example 1. Ammonia can only be synthesized at 500-600°C and 35MPa. The ammonia synthesis rate is 610μmol / (gh).

[0067] Comparative Example 2

[0068] The difference from Example 1 is that all the auxiliary agents are kaolin, and the rest are the same as Example 1. The rate of synthetic ammonia is 3020 μmol / (gh).

[0069] Comparative Example 3

[0070] The difference from Example 1 is that all the auxiliary agents are diatomaceous earth, and the rest are the same as Example 1. The rate of synthetic ammonia is 4500 μmol / (gh).

[0071] Comparative Example 4

[0072] The difference from Example 1 is that all the auxiliary agents are calcium carbonate powder, and the rest are the same as Example 1. The rate of synthetic ammonia is 2200 μmol / (gh).

Claims

1. A porous catalyst for preparing green ammonia, characterized in that: The raw material components include: 50-70% austenite iron powder, 15-20% silica gel, and the balance of auxiliary agent, which is a mixture of kaolin, calcium carbonate powder and diatomaceous earth.

2. The porous catalyst for preparing green ammonia according to claim 1, characterized in that: The auxiliary agent is a mixture of kaolin, calcium carbonate powder and diatomaceous earth in a mass ratio of 1: (0.2-0.5): (1-1.2).

3. The porous catalyst for preparing green ammonia according to claim 1 or 2, characterized in that: The fineness of austenitic iron powder is 100-300 mesh.

4. The porous catalyst for preparing green ammonia according to claim 1 or 2, characterized in that: The raw material components also include: 0.3-0.6% beryllium powder.

5. The porous catalyst for preparing green ammonia according to claim 6, characterized in that: The raw material components also include: 0.1-0.3% scandium powder.

6. The porous catalyst for preparing green ammonia according to claim 5, characterized in that: The fineness of beryllium powder and scandium powder is 250-350 mesh.

7. A method for preparing a porous catalyst for preparing green ammonia according to any one of claims 1 to 6, characterized in that: Austenitic iron powder, silica gel and additives are mixed evenly, extruded into granules, heated to 800-1000°C at a rate of 6-8°C / min under nitrogen protection, calcined for 8-10 hours, and naturally cooled to room temperature to obtain a porous catalyst.

8. The preparation method according to claim 7, characterized in that: If the raw material components also include: beryllium powder and / or scandium powder, first mix the austenitic iron powder, beryllium powder and / or scandium powder, and the additives, then add silica gel and mix, extrude and granulate, then heat to 800-1000°C at a rate of 6-8°C / min under nitrogen protection, calcine at this temperature for 8-10 hours, and cool naturally to room temperature to obtain a porous catalyst.

9. Use of a porous catalyst for preparing green ammonia according to any one of claims 1 to 6, characterized in that: Used to catalyze the synthesis of ammonia from hydrogen and nitrogen; the reaction temperature is 300-350℃ and the pressure is 1~7MPa.

Images