Patent Application
20240228309
The present disclosure relates to a technical field of preparing ammonia synthesis catalysts, and in particular, to a porous ammonia synthesis catalyst and its preparation method and use.
Ammonia is one of the most important raw materials for synthetic chemical products and fertilizers, and has significant application prospects in a field of hydrogen storage in recent years. In 1904, Haber first used iron-based catalysts to prepare ammonia from hydrogen and nitrogen as raw materials under conditions of high temperature and high pressure. In 1913, its industrialization was achieved by Bosch. Subsequently, the research on ammonia synthesis has been widely concerned and developed rapidly. Almquist et al. studied the relationship between the activity of pure iron catalysts and iron components at different valence states, confirming that Fe3O4-based catalyst has the highest activity. Bridger et al. found that the introduction of Al2O3—K2O double additives can greatly improve the catalytic activity of iron-based catalysts. In 1979, the British Imperial Chemical Industry Group took the lead in using cobalt oxide as an additive and developed the Fe2Co-based catalyst, further improving the catalytic activity. In 1985, Huazhang LIU et al. discovered that Fe1-xO-based catalysts with a Wustite structure had higher catalytic activity for ammonia synthesis and achieved industrialization. And in 1992, British Petroleum Company and Kellogg Corporation of America jointly developed the first ruthenium-based catalyst and its process (KAAP), the ruthenium-based catalyst is considered as the second-generation ammonia synthesis catalyst.
The iron-based catalyst for industrial ammonia synthesis is prepared by melting Fe3O4 with different types of accelerators, such as Al2O3, CaO, K2O, at a temperature of about 2000K. The ammonia synthesis process needs to be carried out at a high temperature (400° C. to 600° C.) and high pressure (10 MPa to 30 MPa), and has the disadvantages of high energy consumption that accounts for 1% to 2% of global energy annually, and large emissions of greenhouse gases, such as CO2. Harsh reaction conditions will further lead to serious sintering of the catalyst and loss of active sites. And Ruthenium based catalyst has poor stability, for example, easy sintering and aggregation at high temperature and thus hydrogen poisoning, and has higher preparation costs than cheap transition metals. Therefore, the development of a novel catalyst with low-cost, environmentally friendly, less energy consuming, more stable that can achieve ammonia synthesis under mild conditions has become an important research topic in recent times.
In view of the problems in the existed ammonia synthesis catalysts, an object of the present disclosure is to provide a porous ammonia synthesis catalyst, preparation method thereof, and use, which can efficiently catalyze ammonia synthesis at low temperature and low pressure conditions, and has an application prospect of replacing the existed industrial ammonia synthesis catalyst.
The technical solution of the present disclosure is: a porous ammonia synthesis catalyst is prepared by a sol-gel method using a metal complex as a templating agent and using a silicon source as a raw material. The metal complex is a compound formed by metal ion and an organic ligand through coordination bond. The metal ion is composed of one or more of boron ion, sodium ion, potassium ion, magnesium ion, calcium ion, barium ion, cesium ion, aluminum ion, zirconium ion, nickel ion, titanium ion, cobalt ion, manganese ion, vanadium ion, chromium ion, iron ion, copper ion, zinc ion, tungsten ion, platinum ion, ruthenium ion, rhodium ion, palladium ion, lanthanum ion, cerium ion, praseodymium ion, samarium ion, neodymium ion, and dysprosium ions mixed in a ratio. The organic ligand is an organic compound containing two or more elements of nitrogen, phosphorus, and oxygen mixed in a ratio.
Further, the organic ligand is preferably a carboxylic acid ligand, and the carboxylic acid ligand is preferably one or more of benzoic acid, pyridine carboxylic acid, terephthalic acid, formic acid, acetic acid, propionic acid, 1-naphthoic acid, and 2-naphthoic acid.
Further, the silicon source is preferably a silicate ester, sodium metasilicate, and chlorosilane; and the silicate ester is preferably one or more of methyl orthosilicate, tetraethyl orthosilicate, tetrabutyl orthosilicate, and tetraisopropyl orthosilicate.
Further, the porous ammonia synthesis catalyst is a silicate catalytic material containing a metal active center, and a molar ratio of silicon to the metal active center is (2 to 100):1.
Further, the porous ammonia synthesis catalyst has a specific surface area ranging from 50 m2/g to 800 m2/g and a pore size ranging from 1 nm to 10 nm.
Further, the porous ammonia synthesis catalyst is an iron-based catalyst. The metal ion is composed of iron ion and other co-catalytic element ions mixed in a ratio. The other co-catalytic element ions are one or more of boron ion, sodium ion, potassium ion, magnesium ion, calcium ion, barium ion, cesium ion, aluminum ion, zirconium ion, nickel ion, titanium ion, cobalt ion, manganese ion, vanadium ion, chromium ion, copper ion, zinc ion, tungsten ion, platinum ion, ruthenium ion, rhodium ion, palladium ion, lanthanum ion, cerium ion, praseodymium ion, samarium ion, neodymium ion, and dysprosium ion. The catalytic efficiency of the catalyst is greatly improved by in-situ introducing an iron active center into the porous metal silicate material and doping different co-catalytic elements.
A preparation method of the porous ammonia synthesis catalyst that is prepared by a sol-gel method, comprises the following steps. A silicon source is added into a metal carboxylate solution, and is stirred to be fully dissolved. Then, the metal carboxylate solution is placed into a hydrothermal reaction vessel, and is placed into an oven for hydrothermal reaction to form a gel. After being dried, the gel is transferred to a muffle furnace to programed-heat to 100° C.-1000° C. in an air atmosphere, and is calcined at a constant temperature for 1 hours to 24 hours. Or, the gel is placed into a tubular furnace, is heated to 100° C.-1000° C. in an inert atmosphere, and is calcined at a constant temperature for 1 hours to 24 hours, obtaining the porous ammonia synthesis catalyst.
Further, the metal carboxylate solution is prepared by dissolving a carboxylic acid ligand and a metal salt in a solvent in a molar ratio of (0.5 to 10):1. The metal ion in the metal salt is composed of one or more of boron ion, sodium ion, potassium ion, magnesium ion, calcium ion, barium ion, cesium ion, aluminum ion, zirconium ion, nickel ion, titanium ion, cobalt ion, manganese ion, vanadium ion, chromium ion, iron ion, copper ion, zinc ion, tungsten ion, platinum ion, ruthenium ion, rhodium ion, palladium ion, lanthanum ion, cerium ion, praseodymium ion, samarium ion, neodymium ion, and dysprosium ion mixed in a ratio. The solvent is one or more of water, methanol, ethanol, N,N-dimethylformamide, acetonitrile, and acetone mixed in any ratio.
Further, the metal carboxylate is preferably a benzoate. The metal salt is dissolved in the solvent in a molar ratio of (1 to 5):(0.5 to 1).
Further, the concentration of metal ion in the metal carboxylate solution is 0.1 mmol/L to 1 mmol/L.
Further, the metal salt is a substance dissolvable in a solvent, e.g., a chloride, a nitrate, an acetate, a sulfate.
Further, the conditions of the hydrothermal reaction are: 80° C. to 200° C., 6 hours to 48 hours.
The porous ammonia synthesis catalyst is applied in a synthesis ammonia reaction.
Further, a specific operation is: the porous ammonia synthesis catalyst is mixed with quartz sand and filled into a reactor. The reaction gas is a mixing gas of nitrogen and hydrogen, and a ratio of nitrogen to hydrogen is (0.1 to 10):1. A reaction condition is 0.1 MPa to 15 MPa. A reaction temperature is 150° C. to 450° C. And a reaction space velocity is IL·g−1·h−1 to 72 L·g−1·h−1.
Compared with the prior art, the present disclosure has the following effects:
The present disclosure provides a porous ammonia synthesis catalyst, its preparation method, and its use. The porous ammonia synthesis catalyst takes porous metal silicate as a skeleton, and the catalytic activity center is composed of one or more metals in proportion, which has low raw material cost, easily prepared catalyst and low energy consumption. When the porous ammonia synthesis catalyst is applied to catalytic synthesis of ammonia, the reaction pressure and temperature are low, the catalytic efficiency is high, the energy consumption is low, pollution is avoided, and the catalyst can be used for a long time with high activity.
The following embodiments will assist in understanding the present disclosure, but the scope of protection of the present disclosure is not limited thereto.
Benzoic acid (13.44 mmol), ferric nitrate (2.24 mmol), cesium chloride (0.112 mmol), and tetraethyl orthosilicate (6.72 mmol) were added to a mixing solvent of 4 mL of N,N-dimethylformamide and 0.5 mL of water, stirred at 120° C. for 3 hours, cooled to room temperature, and stirred overnight. The mixture was placed into a hydrothermal reaction vessel, and aged at 160° C. for 24 hours to form a gel. The dried gel was transferred to a muffle furnace and calcined at 600° C. for 5 hours in an air atmosphere to obtain a solid material named as PMS-100. The porous ammonia synthesis catalyst has a specific surface area of 427 m2/g, a uniform pore distribution, and an average pore size of 0.96 nm.
Benzoic acid (13.44 mmol), ferric nitrate (2.24 mmol), and tetraethyl orthosilicate (6.72 mmol) were added to a mixing solvent of 4 mL of N,N-dimethylformamide and 0.5 mL of water, stirred at 120° C. for 3 hours, cooled to room temperature, and stirred overnight. The mixture was placed into a hydrothermal reaction vessel, and aged at 160° C. for 24 hours to form a gel. The dried gel was transferred to a muffle furnace, and calcined at 600° C. for 5 hours in an air atmosphere to obtain a solid material named as PMS-100-a. The porous ammonia synthesis catalyst has a specific surface area of 475 m2/g, a uniform pore distribution, and an average pore size of 0.83 nm.
Benzoic acid (13.44 mmol), ferric nitrate (2.24 mmol), calcium chloride (0.112 mmol), and tetraethyl orthosilicate (6.72 mmol) were added to a mixing solvent of 4 mL of N, N-dimethylformamide and 0.5 mL of water, stirred at 120° C. for 3 hours, cooled to room temperature, and stirred overnight. The mixture was placed into a hydrothermal reaction vessel, and aged at 160° C. for 24 hours to form a gel. The dried gel was transferred to a muffle furnace and calcined at 600° C. in an air atmosphere to obtain a solid material named as PMS-100-b. The porous ammonia synthesis catalyst has a specific surface area of 456 m2/g, a uniform pore distribution, and an average pore size of 0.90 nm.
Benzoic acid (13.44 mmol), ferric nitrate (2.24 mmol), boric acid (0.112 mmol), and tetraethyl orthosilicate (6.72 mmol) were added to a mixing solvent of 4 mL of N,N-dimethylformamide and 0.5 mL of water, stirred at 120° C. for 3 hours, cooled to room temperature, and stirred overnight. The mixture was placed into a hydrothermal reaction vessel, and aged at 160° C. for 24 hours to form a gel. The dried gel was transferred to a muffle furnace, and calcined at 600° C. in an air atmosphere to obtain a solid material named as PMS-100-c. The porous ammonia synthesis catalyst has a uniform pore distribution, and a specific surface area and average pore size similar to the material of the aforementioned examples.
Benzoic acid (13.44 mmol), ferric nitrate (2.24 mmol), aluminum chloride (0.112 mmol), and tetraethyl orthosilicate (6.72 mmol) were added to a mixing solvent of 4 mL of N,N-dimethylformamide and 0.5 mL of water, stirred at 120° C. for 3 hours, cooled to room temperature, and stirred overnight. The mixture was placed into a hydrothermal reaction vessel, and aged at 160° C. for 24 hours to form a gel. The dried gel was transferred to a muffle furnace and calcined at 600° C. in an air atmosphere to obtain a solid material named as PMS-100-d. The porous ammonia synthesis catalyst has a uniform pore distribution, and a specific surface area and average pore size similar to the material of the aforementioned examples.
Benzoic acid (13.44 mmol), ferric nitrate (2.24 mmol), aluminum chloride (0.112 mmol), potassium nitrate (0.224 mmol), and tetraethyl orthosilicate (6.72 mmol) were added to a mixing solvent of 4 mL of N,N-dimethylformamide and 0.5 mL of water, stirred at 120° C. for 3 hours, cooled to room temperature, and stirred overnight. The mixture was placed into a hydrothermal reaction vessel, and aged at 160° C. for 24 hours to form a gel. The dried gel was transferred to a muffle furnace, and calcined at 600° C. in an air atmosphere to obtain a solid material named as PMS-100-e. The porous ammonia synthesis catalyst has a uniform pore distribution, and a specific surface area and average pore size similar to the material of the aforementioned examples.
Benzoic acid (13.44 mmol), ferric nitrate (2.24 mmol), chromium nitrate (0.112 mmol), and tetraethyl orthosilicate (6.72 mmol) were added to a mixing solvent of 4 mL of N,N-dimethylformamide and 0.5 mL of water, stirred at 120° C. for 3 hours, cooled to room temperature, and stirred overnight. The mixture was placed into a hydrothermal reaction vessel, and aged at 160° C. for 24 hours to form a gel. The dried gel was transferred to a muffle furnace and calcined at 600° C. in an air atmosphere to obtain a solid material named as PMS-100-f. The porous ammonia synthesis catalyst has a uniform pore distribution, and a specific surface area and average pore size similar to the material of the aforementioned examples.
Benzoic acid (13.44 mmol), ferric nitrate (2.24 mmol), cerium chloride (0.112 mmol), and tetraethyl orthosilicate (6.72 mmol) were added to a mixing solvent of 4 mL of N,N-dimethylformamide and 0.5 mL of water, stirred at 120° C. for 3 hours, cooled to room temperature, and stirred overnight. The mixture was placed into a hydrothermal reaction vessel, and aged at 160° C. for 24 hours to form a gel. The dried gel was transferred to a muffle furnace and calcined at 600° C. in an air atmosphere to obtain a solid material named as PMS-100-g. The porous ammonia synthesis catalyst has a uniform pore distribution, and a specific surface area and average pore size similar to the material of the aforementioned examples.
The evaluation of activity of the catalyst was carried out in a high-pressure activity testing device having a reactor with an inner diameter of 8 mm. The catalyst prepared in Examples 1-8 or commercial catalyst (see Table 1 for specific amount) was mixed with a certain amount of quartz sand and filled into a stainless steel reactor. The reaction gas was a mixing gas of nitrogen and hydrogen with a nitrogen hydrogen ratio of 1:3, a reaction pressure of 2 MPa, a reaction temperature of 350° C., and a reaction space velocity of 9 L·g−1·h−1. The reaction gas was absorbed by a dilute sulfuric acid aqueous solution, and the concentration of ammonium ions in the absorption solution was determined by ion chromatography. As shown in Table 1, under the same conditions, when the catalyst of the present disclosure is used for catalytic ammonia synthesis, its catalytic efficiency is much higher than the catalytic efficiency of DNCA type industrial ammonia synthesis catalyst and commercial ruthenium carbon catalyst, indicating that the present disclosure has a good industrial application prospect.
0.2 g of PMS-100/PMS-100-a/DNCA was mixed with a certain amount of quartz sand respectively and filled in a stainless steel reactor. The reaction gas was a mixing gas of nitrogen and hydrogen with a nitrogen hydrogen ratio of 1:3, a reaction pressure of 2 MPa, a reaction temperature from 250° C. to 400° C. at intervals of 25° C., and a reaction space velocity of 9 L·g−1·h−1. The reaction gas was absorbed with a dilute sulfuric acid aqueous solution at each temperature condition, and the concentration of ammonium ions in the absorption solution was determined by ion chromatography. The results are shown in
Benzoic acid (26.88 mmol), ferric nitrate (4.48 mmol), cobalt nitrate (0.112 mmol), and tetraethyl orthosilicate (6.72 mmol) were added to a mixing solvent of 4 mL of N,N-dimethylformamide and 0.5 mL of water, stirred at 120° C. for 3 hours, cooled to room temperature, and stirred overnight. The mixture was placed into a hydrothermal reaction vessel, and aged at 100° C. for 12 hours to form a gel. The dried gel was transferred to a muffle furnace, and calcined at 400° C. for 8 hours in an air atmosphere to obtain a solid material. The porous ammonia synthesis catalyst has a uniform pore distribution, a specific surface area and average pore size similar to the materials of the aforementioned examples, and good ammonia synthesis catalytic efficiency.
Formic acid (13.44 mmol), platinum nitrate (1.344 mmol), and methyl orthosilicate (6.72 mmol) were added to a mixing solvent of 4 mL of N,N-dimethylformamide and 0.5 mL of water, stirred at 120° C. for 3 hours, cooled to room temperature, and stirred overnight. The mixture was placed into a hydrothermal reaction vessel, and aged at 120° C. for 16 hours to form a gel. The dried gel was transferred to a muffle furnace, and calcined at 100° C. for 24 hours in an air atmosphere to obtain a solid material. The porous ammonia synthesis catalyst has a uniform pore distribution, a specific surface area and average pore size similar to the materials of the aforementioned examples, and good ammonia synthesis catalytic efficiency.
Acetic acid (1.12 mmol), cobalt nitrate (2.24 mmol), and sodium metasilicate (6.72 mmol) were added to 4 mL of water, stirred at 100° C. for 4 hours, cooled to room temperature, and stirred overnight. The mixture was placed into a hydrothermal reaction vessel, and aged at 200° C. for 20 hours to form a gel. The dried gel was transferred to a tubular furnace, and calcined at 600° C. for 1 hours in a nitrogen atmosphere to obtain a solid material. The porous ammonia synthesis catalyst has a uniform pore distribution, a specific surface area and average pore size similar to the materials of the aforementioned examples, and good ammonia synthesis catalytic efficiency.
Terephthalic acid (13.44 mmol), rhodium chloride (2.24 mmol), cesium chloride (0.112 mmol), and chlorosilane (235.2 mmol) were added to a mixing solvent of 4 mL of N,N-dimethylformamide and 0.5 mL of water, stirred at 120° C. for 3 hours, cooled to room temperature, and stirred overnight. The mixture was placed into a hydrothermal reaction vessel, and aged at 160° C. for 36 hours to form a gel. The dried gel was transferred to a muffle furnace, and calcined at 600° C. for 4.5 hours in an air atmosphere to obtain a solid material. The porous ammonia synthesis catalyst has a uniform pore distribution, a specific surface area and average pore size similar to the materials of the aforementioned examples, and good ammonia synthesis catalytic efficiency.
1-naphthoic acid (13.44 mmol), ferric nitrate (2.24 mmol), cerium chloride (0.112 mmol), and tetraisopropyl orthosilicate (6.72 mmol) were added to a mixing solvent of 4 mL of N,N-dimethylformamide, and 0.5 mL of water, stirred at 120° C. for 3 hours, cooled to room temperature, and stirred overnight. The mixture was placed into a hydrothermal reaction vessel, and aged at 200° C. for 48 hours to form a gel. The dried gel was transferred to a muffle furnace, and calcined at 600° C. for 5 hour in an air atmosphere to obtain a solid material. The porous ammonia synthesis catalyst has a uniform pore distribution, a specific surface area and average pore size similar to the materials of the aforementioned examples, and good ammonia synthesis catalytic efficiency.
The above is only part of embodiments of the present disclosure, and any equivalent changes and modifications made according to the claims of the patent disclosure shall fall within the scope of the present disclosure.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/CN2023/071010 | Jan 2023 | WO |
| Child | 18454824 | US |
