Nitrous oxide trapping and separating adsorbent as well as preparation method and application thereof

Abstract

The invention discloses a nitrous oxide trapping and separating adsorbent as well as a preparation method and application thereof. The preparation method comprises the following steps: in a protective gas atmosphere, adding an anhydride compound, a polyamine compound, a cross-linking agent and a catalyst into a reaction solvent for reaction; and after the reaction is finished, obtaining a precipitate, separating, washing and drying to obtain the nitrous oxide trapping and separating adsorbent. The anhydride compound is a compound containing more than two carboxylic acid anhydride functional groups; the polyamine compound is a compound containing more than two NH2 functional groups; the cross-linking agent is triaminopyrimidine; the catalyst is isoquinoline. According to the method, the anhydride compound, the polyamine compound and the triaminopyrimidine are used as raw materials, cross-linking polymerization is performed through imidization reaction, the reaction conditions are simple and easy to control, the reaction raw materials are low in cost, adsorbents with different pore structures can be prepared, and N2O in mixed gas is captured and separated through simple, low-consumption and efficient pressure swing adsorption.

Description

Technical Field

[0001] The present invention relates to the technical field of greenhouse gas capture and separation, and in particular to a nitrous oxide capture and separation adsorbent, a preparation method and an application thereof. Background Art

[0002] The three major greenhouse gases are CO 2 , CH 4 and N 2 O. N as nitrous oxide 2 As the third largest greenhouse gas, O has undoubtedly had a huge impact on global warming, and N 2 O may also cause ozone holes, thereby increasing the intensity of ultraviolet radiation. 2 O not only affects the atmosphere, but also forms nitrates when it dissolves in the atmosphere, which enter the water body through rainfall and other means, causing eutrophication of the water body, which in turn affects the balance of the aquatic ecosystem. 2 O, and due to human industrial activities, its content is still increasing year by year. 2 Although O will have a negative impact on the atmospheric environment, high-purity N 2 O also has practical applications in many areas of life, such as medicine, electronics, food, etc. 2 O Recycling and utilizing it is the best choice from both environmental and economic perspectives.

[0003] N 2 The emission of O is mainly natural and human activities. Among them, people emit N 2 O accounts for as much as 40% of the total. In current industrial activities, we cannot simply reduce N 2 O emissions, it is also necessary to 2 O treatment, treatment of N in tail gas from adipic acid or nitric acid production 2 O usually uses the following methods: 1) Decomposition method, that is, N 2 O decomposes into non-greenhouse gas N 2 and O 2 , but this method has strict requirements on operating conditions and catalysts, is energy-consuming and not environmentally friendly; 2) directly converting N 2 O is used as an oxidant, such as N 2 O can oxidize benzene to phenol in one step. Obviously, this method also requires high-purity N 2 Therefore, it is necessary to find a way to capture N in a low-energy and environmentally friendly way. 2 O is very meaningful.

[0004] From the comparison of many treatment methods, the adsorption process has the advantages of relatively simple preparation process, high efficiency, low energy consumption, and the ability to obtain high-purity target gas, and is more suitable for separating N 2 O is a means of separation. Among them, pressure swing adsorption separation of binary mixed gases has received a lot of attention in recent years. For pressure swing adsorption, the most important thing is to find an adsorption separation material with excellent performance. Since the performance of the material directly affects the separation efficiency, the purity of the target product, and the sustainable working time, the adsorption separation material is crucial to the industrialization and popularization of this technology. Among many adsorption materials, compared with molecular sieves and activated carbon, polyimide PIs has obvious advantages and excellent comprehensive performance. It has excellent thermal stability, mechanical properties, rich pore structure, adjustable pore size, and functionalization, etc., showing great potential in the adsorption and separation of gases.

[0005] CN108837678A discloses a method for treating nitrogen oxide waste gas, which includes enrichment treatment of NOx waste gas and SCR treatment of NOx waste gas. The enrichment treatment includes the following steps: preparing an aqueous solution of glycidyl ether in a soaking container, soaking a filler plate made of polyimide, and drying at 75-85°C to obtain an enrichment filler; placing the enrichment filler in a pipeline for discharging waste gas, and the cross section of the enrichment filler is equal to the cross section of the pipeline for discharging waste gas; during SCR treatment, placing the enrichment filler after enriching the waste gas in an SCR system for treatment; after the SCR treatment is completed, air is passed into the SCR reaction system to replace the gas, the polyimide filler plate is taken out, the pH of the SCR reaction system is adjusted to 5.5, and FeCl is added 3 and ethanol until solids are completely precipitated, and the filtrate is filtered and dripped with NaOH aqueous solution until solids are completely precipitated, which can enrich NOx waste gas and then be treated in a centralized manner. However, this method for treating nitrogen oxide waste gas has the following defects: (1) it uses aromatic diamine and aromatic tetracarboxylic acid dialkyl ester to prepare condensation-type aromatic polyimide, which is only used as filler and soaked as enrichment filler. Pd (palladium) precious metal is used in the enrichment filler, which is relatively expensive; (2) the entire treatment process is extremely complicated and energy-intensive.

[0006] For example, CN114191981A discloses a harmless treatment method for industrial waste gas, which includes the following steps: passing the flue gas containing nitrogen oxides into a dust removal device for dust removal to obtain dust-removed flue gas; passing the dust-removed flue gas into a desulfurization device for desulfurization to obtain desulfurized flue gas; adjusting the temperature of the desulfurized flue gas to 100-200°C, passing it into an SCR denitrification device equipped with a denitration filter material, wherein the denitration filter material is a polyimide fiber filter material covalently grafted with a denitration catalyst, and passing ammonia into the SCR denitrification device for selective catalytic reduction denitration to complete the harmless treatment of the flue gas. However, this method has the following defects: in the gas denitration link, it is to pass the heated gas through a polyimide fiber filter material covalently grafted with a denitration catalyst, which is mainly a catalyst preparation method and denitration by chemical reaction method, and the selection of polyimide is not described.

[0007] For example, CN118028999A discloses a method for preparing high-performance polyimide fibers by two-step chemical imidization, which comprises the following steps: adding a certain amount of polyamino compound to a polyamic acid spinning stock solution prepared by polycondensation of dianhydride and diamine monomers to obtain a slightly cross-linked polyamic acid solution; adding a certain amount of imidization agent to the above polyamic acid solution to carry out a first imidization reaction to obtain a polyamic acid spinning solution with a certain degree of pre-imidization; according to a wet spinning process, the spinning solution is directly extruded through a spinneret and then enters a coagulation bath composed of an imidization agent to carry out a second imidization reaction to obtain gelled primary fibers, and high-multiple drafting is carried out at this stage; thereafter, partially imidized fibers are obtained after washing and drying; and finally, polyimide fibers are obtained after further thermal cyclization and drafting. However, this method has the following defects: (1) its preparation method is to first prepare a slightly cross-linked polyamic acid solution, then add an imidization agent to obtain a pre-imidized polyamic acid spinning solution, and then perform a second imidization reaction to obtain a gelled primary fiber. The preparation steps are numerous and complicated; (2) the cross-linking of the obtained polyimide fiber is not sufficient.

[0008] For another example, CN111748113A discloses a heat-resistant low dielectric constant polyimide film, whose raw materials include: diamine monomer, dianhydride monomer, 2,4,6-triaminopyrimidine, octa(aminophenyltrioxysilane) and modified nano hollow silica, wherein the content of modified silica is 3.5-4.5wt%. The application also discloses a preparation method of the above-mentioned heat-resistant low dielectric constant polyimide film: in an inert gas atmosphere, the diamine monomer, 2,4,6-triaminopyrimidine, modified nano hollow silica and N,N-dimethylacetamide are ultrasonically mixed, and then the dianhydride monomer is added to react at room temperature for 3-5h, and then octa(aminophenyltrioxysilane) is added to continue the reaction for 1-2h to obtain a glue solution; the glue solution is degassed and coated on the surface of the substrate, imidized, naturally cooled to room temperature, and the film is removed to obtain the heat-resistant low dielectric constant polyimide film. However, the preparation method of the polyimide film disclosed in the patent application has the following defects: (1) In the preparation process, it is necessary to first mix and prepare the glue solution, and then go through multiple steps of heating operation, and the reaction steps are complicated; (2) The prepared material does not have N 2 O gas separation performance.

[0009] For example, "Designed synthesis of large-pore crystalline polyimide covalentorganic framework" (Qianrong Fang, Yushan Yan, et al., Nature Communications, Vol. 5, No. 1, 8 pages) discloses the use of dianhydride and triamine to prepare polyimide COFs (porous crystalline polymers) through imidization reaction, and the pore size can be as large as The specific surface area is as high as 2346m 2 / g, which is a relatively high level among amorphous porous polyimide and two-dimensional COFs. However, its reaction conditions are relatively harsh, energy consumption is high, product cost is higher, and it is not easy to apply industrially.

[0010] Another example is "Effect of the Number of Methyl Groups in DMOF on N 2 O Adsorption and N 2 O / N 2 Separation" (Li Wang, Jiangfeng Yang, et al., Inorganic Chemistry, Vol. 63, No. 25, pp. 11501-11505) studied the effects of DMOF (metal organic framework) materials with different polarity and ligand methyl numbers on N 2 O adsorption. The simulation method proves that the surface methyl groups are adsorbed on N 2O plays a key role in the preferential affinity. However, the preparation cost of adsorbent materials with metal organic frameworks is high and it is not easy to industrialize.

[0011] Therefore, a preparation method is provided which has simple reaction conditions, low preparation cost, and can effectively capture and separate N 2 Polyimide adsorbents for O gas have become an urgent problem to be solved in the industry. Summary of the invention

[0012] The purpose of the present invention is to provide a nitrous oxide capture and separation adsorbent and its preparation method and application. The present invention uses anhydride compounds, polyamine compounds and triaminopyrimidine as raw materials, and crosslinks and polymerizes through imidization reaction. The reaction conditions are simple and easy to control, and the cost of the reaction raw materials is low. A polyimide adsorbent with different pore structures can be prepared; it is used as a nitrous oxide capture and separation adsorbent to capture and separate N in a mixed gas by simple, low-consumption, and high-efficiency pressure swing adsorption. 2 O.

[0013] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0014] The first aspect of the present invention provides a method for preparing a nitrous oxide capture and separation adsorbent, comprising the following steps:

[0015] In a protective gas atmosphere, an anhydride compound, a polyamine compound, a crosslinking agent and a catalyst are added to a reaction solvent to react; after the reaction is completed, a precipitate is obtained, separated, washed and dried to obtain a polyimide adsorbent, namely, a nitrous oxide capture and separation adsorbent;

[0016] The acid anhydride compound is a compound containing two or more carboxylic anhydride functional groups; the polyamine compound is a compound containing two or more NH 2 The compound has a functional group; the cross-linking agent is triaminopyrimidine; and the catalyst is isoquinoline.

[0017] According to the preparation method of the present invention, preferably, the acid anhydride compound is selected from one or a combination of two or more of 1,4,5,8-naphthalenetetracarboxylic anhydride (NTCDA), pyromellitic dianhydride (PMDA), 3,4,9,10-perylenetetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), 4,4'-oxydiphthalic anhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA), 1,2,3,4-butanetetracarboxylic dianhydride, mellitic acid trianhydride, terphenylene [2,3-c:6,7-c':10,11-c"]trifuran-1,3,6,8,11,13-hexaketone or hexaazatrimellitic acid trianhydride; wherein the combined acid anhydride compounds can be mixed in any proportion.

[0018] Specifically, the structural formulas corresponding to the above anhydride compounds are as follows:

[0019]

[0020]

[0021] More preferably, the anhydride compound is selected from one or a combination of two or more of mellitic acid trianhydride, terphenylene [2,3-c:6,7-c':10,11-c"]trifuran-1,3,6,8,11,13-hexaketone or hexaazatrimellitic acid trianhydride; wherein the combined anhydride compounds can be mixed in any proportion.

[0022] In the present invention, the more carboxylic anhydride functional groups there are in the acid anhydride compound, the more effective the synthesized adsorbent is for N 2 The greater the adsorption capacity of O; the more nitrogen atoms in the anhydride compound, the greater the adsorption capacity of the synthesized adsorbent for N 2 The O adsorption capacity is also larger.

[0023] According to the preparation method of the present invention, preferably, the polyamine compound is selected from one or a combination of two or more of benzidine, tris(4-aminophenyl)amine (TAPA), 1,3,5-tris(4-aminophenyl)benzene (TAPB), 3,3'-diaminobenzidine, 4',5'-bis(4-aminophenyl)-[1,1':2',1"-terphenyl]-4,4"-diamine, tetrakis(4-aminophenyl)methane, N,N,N',N'-tetrakis(p-aminophenyl)p-phenylenediamine, hexa(4-aminohexaphenyl)benzene, 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, and 4',4"',4""'-(1,3,5-triazine-2,4,6-triyl)tris(([1,1'-biphenyl]-4-amine)); wherein the combined polyamine compounds can be mixed in any proportion.

[0024] Specifically, the structural formulas of the above polyamine compounds are as follows:

[0025]

[0026]

[0027] More preferably, the polyamine compound is selected from one or a combination of tris(4-aminophenyl)amine (TAPA) and 2,4,6-tris(4-aminophenyl)-1,3,5-triazine; wherein the combined polyamine compounds can be mixed in any proportion.

[0028] According to the preparation method of the present invention, preferably, the triaminopyrimidine is selected from one or a combination of two or more of 2,4,6-triaminopyrimidine (TAP), 4,5,6-triaminopyrimidine or 2,4,5-triaminopyrimidine; wherein the combined compounds can be mixed in any proportion.

[0029] Specifically, the structural formula of the above triaminopyrimidine is as follows:

[0030]

[0031] According to the preparation method of the present invention, preferably, the reaction solvent is selected from one or a combination of two or more of N,N-dimethylformamide (DMF), N,N-dimethylacetamide, N-methylpyrrolidone (NMP), 1,3-dimethyl-2-imidazolidinone, 1,1,3-trimethylcyclohexenone, m-cresol, dodecane, diphenyl ether, cyclopentane, toluene, propylbenzene, mesitylene, and o-dichlorobenzene; wherein the combined reaction solvents can be mixed in any proportion.

[0032] According to the preparation method of the present invention, preferably, the reaction temperature is 100 to 300°C and the reaction time is 24 to 200 hours. In the preparation process of the present invention, when the reaction temperature is higher than 300°C, the reaction product will decompose; when the reaction temperature is lower than 100°C, the reaction activation effect of the reactant cannot be achieved. The specific setting of the reaction temperature is determined by the boiling point of the reaction solvent, so as to facilitate condensation reflux.

[0033] According to the preparation method of the present invention, preferably, the molar ratio of the total amount of the polyamine compound and the cross-linking agent to the acid anhydride is 1:(1-1.5);

[0034] The molar ratio of the polyamine compound to the cross-linking agent is 1:(0.3-3);

[0035] The molar ratio of the catalyst to the acid anhydride compound is (2.5-5):1.

[0036] The amount of the reaction solvent used needs to be able to dissolve all the reactants. When all the reactants are dissolved, the amount of the solvent used has little effect on the reaction rate and yield. The protective gas is an inert gas and nitrogen commonly used in laboratories, and the inert gas includes helium, neon, argon, krypton, xenon, and radon.

[0037] According to the preparation method of the present invention, the separation adopts a separation method such as filtration and suction filtration to separate the precipitate generated in the reaction system; for example, normal pressure suction filtration, reduced pressure suction filtration, etc.

[0038] According to the preparation method of the present invention, preferably, the washing adopts THF or THF and methanol, and is generally washed 3 to 5 times.

[0039] According to the preparation method of the present invention, preferably, the drying conditions include: vacuum drying at 80-110° C. for 24-72 hours.

[0040] In a preferred embodiment, the preparation method comprises:

[0041] First, a prepared reaction solvent is added to a pressure-resistant glass tube or other pressure-resistant container, and then a mixture of anhydride compounds, polyamine compounds and triaminopyrimidine is added, and a catalyst isoquinoline is added. Inert gas protection is introduced, the temperature is set at 100 to 300° C., and a closed reaction is performed for 24 to 200 hours to obtain a precipitate; after separation, washing, and drying, a cross-linked polyimide adsorbent is obtained, namely the nitrous oxide capture and separation adsorbent.

[0042] The second aspect of the present invention provides a nitrous oxide capture and separation adsorbent obtained by any one of the above preparation methods.

[0043] The third aspect of the present invention provides one or more nitrous oxide capture and separation adsorbents for capturing and separating N 2 O gas application.

[0044] According to the application of the present invention, preferably, from 2 Capture and separate N from O mixed gas 2 O gas; the gas containing N 2 O mixed gas is N 2 O / N 2 、N 2 O / H 2 or N 2 O / CH 4 .

[0045] According to the application of the present invention, preferably, the N 2 The temperature for the adsorption separation of O gas is 298-313K, and the pressure for the adsorption separation is 0-4MPa.

[0046] According to the application of the present invention, preferably, the nitrous oxide capture and separation adsorbent is compounded with an ionic liquid.

[0047] According to the application of the present invention, preferably, the mass of the nitrous oxide capture and separation adsorbent and the ionic liquid are fully mixed, dried and then ground. The drying can be vacuum drying, for example, at a temperature of 80 to 150° C., and the time can be determined according to the specific drying effect, which is not limited by the present invention. After drying, the adsorbent and the ionic liquid can be fully combined, and ground after cooling to room temperature.

[0048] When the adsorbent synthesized by the present invention is compounded with an ionic liquid containing a specific functional group, such as a fluorine-containing ionic liquid or an amino-containing ionic liquid, the ionic liquid can increase the active sites and gel the adsorbent to N 2 The O gas adsorption performance is improved. More preferably, the ionic liquid is selected from one or a combination of two or more of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-butyl-3-methylimidazolium hexafluorophosphate, and 1-aminopropyl-3-methylimidazolium bromide; wherein the combined ionic liquids can be mixed in any proportion.

[0049] According to the application of the present invention, preferably, the mass ratio of the nitrous oxide capture and separation adsorbent to the ionic liquid is 95:5.

[0050] When the gas adsorption performance of the nitrous oxide capture and separation adsorbent of the present invention is tested, gas adsorption under various conditions can be used, such as pressure swing adsorption (PSA), temperature swing adsorption (TSA) and a combination of the two, pressure swing temperature adsorption (PTSA).

[0051] In some embodiments, the capture and separation of N 2 O gas or N 2 The adsorption separation temperature of the mixed gas of O was set to 298K, and the adsorption separation pressure was set to 4MPa; 2 The adsorption capacity of O is 4.32~9.09mmol / g, and that of N 2 O / N 2 The separation selectivity is 10.50~100.82.

[0052] The beneficial effects of the present invention include:

[0053] 1) The nitrous oxide capture and separation adsorbent prepared by the present invention has a stable rigid structure, excellent thermal stability, and a rich and adjustable pore structure, and can quickly capture and separate the greenhouse gas nitrous oxide;

[0054] 2) The nitrous oxide capture and separation adsorbent of the present invention has low preparation cost, can be functionalized, and has mild synthesis conditions, and has the potential for industrial production;

[0055] 3) The nitrous oxide capture and separation adsorbent prepared by the present invention separates N 2 The process flow of O mixed gas is simple, low in consumption, high in efficiency, and the target gas obtained is of high purity, which is of great significance for the separation, recovery and utilization of nitrous oxide. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 The infrared spectra of the products PI-1 to 3 prepared in Examples 1 to 3 of the present invention are shown.

[0057] Figure 2 The thermogravimetric spectra of the products PI-1 to 3 prepared in Examples 1 to 3 of the present invention.

[0058] Figure 3a This is the SEM image of the product PI-1 prepared in Example 1 of the present invention.

[0059] Figure 3b This is the SEM image of the product PI-2 prepared in Example 2 of the present invention.

[0060] Figure 3c This is the SEM image of the product PI-3 prepared in Example 3 of the present invention.

[0061] Figure 4 The XRD diagrams of the products PI-1 to PI-3 prepared in Examples 1 to 3 of the present invention are shown in FIG.

[0062] Figure 5a N is the product PI-1 prepared in Example 1 of the present invention 2 O and N 2 Adsorption isotherm curve.

[0063] Figure 5b N is the product PI-2 prepared in Example 2 of the present invention 2 O and N 2 Adsorption isotherm curve.

[0064] Figure 5c N is the product PI-3 prepared in Example 3 of the present invention 2 O and N 2 Adsorption isotherm curve.

[0065] Figure 6 The product PI-1 prepared in Example 1 of the present invention has a certain effect on N under different pressure conditions. 2 O / N 2 Schematic diagram of adsorption selectivity of mixed gases. DETAILED DESCRIPTION

[0066] In order to explain the present invention more clearly, the present invention is further described below in conjunction with preferred embodiments. It should be understood by those skilled in the art that the following specific description is illustrative rather than restrictive, and should not be used to limit the scope of protection of the present invention.

[0067] All numerical specifications herein (e.g., temperature, time, concentration, and weight, etc., including ranges for each thereof) are generally approximate values ​​that may be appropriately varied (+) or (-) in increments of 0.1 or 1.0. All numerical specifications may be understood as being preceded by the term "about."

[0068] Example 1

[0069] This embodiment prepares a nitrous oxide capture and separation adsorbent PI-1, comprising the following steps:

[0070] In a 15mL heat-resistant glass test tube, add 10 ml of a mixed solvent of mesitylene and N-methylpyrrolidone in a volume ratio of 1:1, add 0.327 g (1.5 mmol) of pyromellitic anhydride, 0.218 g (0.75 mmol) of tris(4-aminophenyl)amine and 0.0313 g (0.25 mmol) of 2,4,6-triaminopyrimidine, dropwise add 0.55 g of isoquinoline, fill the heat-resistant glass test tube with nitrogen and seal it. After sealing, heat the reaction mixture at 150°C for 100 hours to obtain a precipitate; separate it by suction filtration (normal pressure organic filter paper), wash it with anhydrous THF and methanol, repeat three times, and finally vacuum dry it at 100°C to remove the solvent to obtain PI-1 in powder form.

[0071] The reaction formula is as follows:

[0072]

[0073] Example 2

[0074] This embodiment prepares a nitrous oxide capture and separation adsorbent PI-2, comprising the following steps:

[0075] In a 15 mL heat-resistant glass test tube, add 10 ml of a mixed solvent of mesitylene and N-methylpyrrolidone in a volume ratio of 1:1, add 0.327 g (1.5 mmol) of pyromellitic anhydride, 0.145 g (0.5 mmol) of tris(4-aminophenyl)amine and 0.0626 g (0.5 mmol) of 2,4,6-triaminopyrimidine, dropwise add 0.55 g of isoquinoline, fill the heat-resistant glass test tube with nitrogen and seal it. After sealing, heat the reaction mixture at 150°C for 100 h to obtain a precipitate, separate it by suction filtration (normal pressure organic filter paper), wash it with anhydrous THF and methanol, repeat three times, and finally vacuum dry it at 100°C to remove the solvent to obtain PI-2 in powder form.

[0076] The reaction formula is as follows:

[0077]

[0078] Example 3

[0079] This embodiment prepares a nitrous oxide capture and separation adsorbent PI-3, comprising the following steps:

[0080] In a 15mL heat-resistant glass test tube, add 10 ml of a mixed solvent of mesitylene and N-methylpyrrolidone in a volume ratio of 1:1, add 0.327 g (1.5 mmol) of pyromellitic anhydride, 0.0726 g (0.25 mmol) of tris(4-aminophenyl)amine and 0.9385 g (0.75 mmol) of 2,4,6-triaminopyrimidine, add 0.55 g of isoquinoline, fill the heat-resistant glass test tube with nitrogen and seal it. After sealing, heat the reaction mixture at 150°C for 100 h to obtain a precipitate, separate it by suction filtration (normal pressure organic filter paper), wash it with anhydrous THF and methanol, repeat three times, and finally vacuum dry it at 100°C to remove the solvent to obtain PI-3 in powder form. The reaction formula is as follows:

[0081]

[0082] Example 4

[0083] This embodiment prepares a nitrous oxide capture and separation adsorbent PI-4, comprising the following steps:

[0084] In a 15 mL heat-resistant glass test tube, add 10 ml of a mixed solvent of toluene and N-methylpyrrolidone in a volume ratio of 1:1, add 0.327 g (1.5 mmol) of pyromellitic anhydride, 0.177 g (0.5 mmol) of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and 0.0626 g (0.5 mmol) of 2,4,6-triaminopyrimidine, dropwise add 0.55 g of isoquinoline, fill the heat-resistant glass test tube with nitrogen and seal it. After sealing, heat the reaction mixture at 100°C for 200 h to obtain a precipitate, separate it by suction filtration (normal pressure organic filter paper), and wash it with anhydrous THF and methanol, repeat three times, and finally vacuum dry it at 80°C to remove the solvent to obtain the product PI-4.

[0085] The reaction formula is as follows:

[0086]

[0087] Example 5

[0088] This embodiment prepares a nitrous oxide capture and separation adsorbent PI-5, comprising the following steps:

[0089] In a 15 mL heat-resistant glass test tube, add 10 ml of a mixed solvent of mesitylene, N,N-dimethylformamide, and 1,3-dimethyl-2-imidazolidinone in a volume ratio of 1:1, add 0.588 g (1.5 mmol) of 3,4,9,10-perylenetetracarboxylic dianhydride, 0.145 g (0.5 mmol) of tris(4-aminophenyl)amine, and 0.0626 g (0.5 mmol) of 2,4,6-triaminopyrimidine, and dropwise add 0.55 g of isoquinoline. The heat-resistant glass test tube is filled with nitrogen and then sealed. After sealing, the reaction mixture is heated at 300°C for 24 hours to obtain a precipitate, which is separated by suction filtration (normal pressure organic filter paper), and washed with anhydrous THF and methanol, repeated three times, and finally vacuum dried at 100°C to remove the solvent to obtain the product PI-5.

[0090] The reaction formula is as follows:

[0091]

[0092] Example 6

[0093] This embodiment prepares a nitrous oxide capture and separation adsorbent PI-6, comprising the following steps:

[0094] In a 15mL heat-resistant glass test tube, add 10 ml of a mixed solvent of mesitylene and N-methylpyrrolidone in a volume ratio of 1:1, add 0.2881 g (1 mmol) of mellitic acid trianhydride, 0.145 g (0.5 mmol) of tris(4-aminophenyl)amine, and 0.0626 g (0.5 mmol) of 2,4,6-triaminopyrimidine, and drop 0.55 g of isoquinoline. Fill the heat-resistant glass test tube with nitrogen and seal it. After sealing, heat the reaction mixture at 150°C for 100 h to obtain a precipitate, separate it by suction filtration (normal pressure organic filter paper), and wash it with anhydrous THF and methanol, repeat three times, and finally vacuum dry it at 100°C to remove the solvent to obtain the product PI-6.

[0095] The reaction formula is as follows:

[0096]

[0097] Example 7

[0098] This embodiment prepares a nitrous oxide capture and separation adsorbent PI-7, comprising the following steps:

[0099] In a 15 mL heat-resistant glass test tube, add 10 ml of a mixed solvent of mesitylene and N-methylpyrrolidone in a volume ratio of 1:1, add 0.4383 g (1 mmol) of triphenylene [2,3-c:6,7-c':10,11-c"]trifuran-1,3,6,8,11,13-hexaketone, 0.145 g (0.5 mmol) of tris(4-aminophenyl)amine and 0.0626 g (0.5 mmol) of 2,4,6-triaminopyrimidine, add 0.55 g of isoquinoline dropwise, fill the heat-resistant glass test tube with nitrogen and seal it. After sealing, heat the reaction mixture at 150°C for 100 h to obtain a precipitate, separate it by suction filtration (normal pressure organic filter paper), and wash it with anhydrous THF and methanol, repeat three times, and finally vacuum dry it at 100°C to remove the solvent to obtain the product PI-7.

[0100] The reaction formula is as follows:

[0101]

[0102] Example 8

[0103] This embodiment prepares a nitrous oxide capture and separation adsorbent PI-8, comprising the following steps:

[0104] In a 15mL heat-resistant glass test tube, add 10 ml of a mixed solvent of mesitylene and N-methylpyrrolidone in a volume ratio of 1:1, add 0.4442 g (1 mmol) of hexaazatrimellitic acid trianhydride, 0.145 g (0.5 mmol) of tris(4-aminophenyl)amine, and 0.0626 g (0.5 mmol) of 2,4,6-triaminopyrimidine, and drop 0.55 g of isoquinoline. Fill the heat-resistant glass test tube with nitrogen and seal it. After sealing, heat the reaction mixture at 150°C for 100 h to obtain a precipitate, separate it by suction filtration (normal pressure organic filter paper), and wash it with anhydrous THF and methanol, repeat three times, and finally vacuum dry it at 100°C to remove the solvent to obtain the product PI-8.

[0105] The reaction formula is as follows:

[0106]

[0107] Example 9

[0108] This example uses the nitrous oxide capture and separation adsorbent PI-2 prepared in Example 2 to prepare PI-9 adsorbent with 5% ILc, including the following steps:

[0109] Weigh 0.95 g of PI-2 adsorbent powder and put it into a glass beaker. Weigh 0.05 g of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt ionic liquid and slowly add it to the beaker. Stir the mixture and mix it evenly by ultrasonication for 30 minutes. Transfer the mixture to a vacuum drying oven and dry it in vacuum at 100°C for 4 hours to fully combine the two. After drying, take out the mixture and cool it to room temperature. Grind the composite to obtain PI-9 adsorbent.

[0110] (I) Test characterization

[0111] (1) Infrared (IR) test characterization

[0112] The present invention conducted infrared spectroscopy tests on the products PI-1, PI-2 and PI-3, and the infrared spectra thereof are shown in FIG. Figure 1 As shown, the products PI-1, PI-2 and PI-3 all showed: 1780cm -1 and 1720cm -1 The peaks near 1375 cm are attributed to the asymmetric and symmetric vibrations of the C=O group of the imine ring; -1 The peak near is caused by the tensile vibration of CNC; 725cm -1 The peaks near the imine are due to the deformation of the imine. These infrared absorption peaks confirm that the material has been successfully imidized, and the obvious 3200cm -1 -3500cm -1 The characteristic peaks of amino groups within the range have completely disappeared in the cross-linked product, proving that the reaction cross-linking synthesis is successful and the product is successfully synthesized.

[0113] (2) Thermogravimetric (TG) test characterization

[0114] The present invention is in N 2 The TG curves of the products PI-1, PI-2 and PI-3 at 25-800°C were measured under the atmosphere. Figure 2 As shown, weightlessness can be divided into three stages:

[0115] The first temperature stage: 25-200°C. The temperature in this stage is not high. Since the sample has complex pores and some water and solvents remain in them, in this temperature stage, the three products remove water molecules and gas molecules remaining in the pores, resulting in a decrease in quality.

[0116] The second stage: 200-400°C. In this temperature stage, the three products lose weight slowly, which is mainly due to the removal of some high-boiling point organic solvents remaining in the three products.

[0117] The third stage: 400-800℃. In this temperature stage, all three products lose weight rapidly. It is the main weight loss stage in the whole thermogravimetric experiment. This stage is caused by the thermal decomposition of the three products. At the same time, the material pore frames of the three products begin to collapse.

[0118] It can be seen that product PI-1, product PI-2 and product PI-3 all have good thermal stability.

[0119] (3) Scanning electron microscope (SEM) test characterization

[0120] The surface structures of the products PI-1, PI-2 and PI-3 were observed by cold field emission scanning electron microscope. Figure 3a to Figure 3c As shown, although the surface morphologies of the three samples are different, they all show a rough surface and have a large number of particles. These characteristics indicate that this series of materials is suitable for use in the field of gas adsorption and separation.

[0121] (4) PXRD test characterization

[0122] The present invention tests the properties of the products PI-1, PI-2 and PI-3 by powder X-ray diffractometer, such as Figure 4 As shown, they all show the common diffuse "mantou peak", indicating that the synthesized materials are amorphous.

[0123] (II) Adsorption capacity test

[0124] (1) Pure gas adsorption test

[0125] The products PI-1, PI-2, PI-3, PI-6, PI-7, PI-8 and PI-9 were measured for the gas N in the pressure range of 0-4 MPa at 298 K using a high temperature and high pressure adsorber analyzer (3H-2000PH, Beijing Best Instrument Technology Co., Ltd.). 2 O and gas N 2 Tables 1 to 7 show the adsorption of products PI-1, PI-2, PI-3, PI-6, PI-7, PI-8 and PI-9 to gas N 2 O and gas N 2 Specific test data of adsorption capacity.

[0126] It can be seen from Tables 1 to 3 that the product PI-1 has a good 2 The adsorption amount of O is for gas N 2 The adsorption capacity of product PI-2 is 10 to 32 times of that of gas N under basically the same pressure conditions. 2 The adsorption amount of O is for gas N 2The adsorption capacity of product PI-3 is 8 to 29 times of that of gas N under basically the same pressure conditions. 2 The adsorption amount of O is for gas N 2 It can be seen that this series of materials has a good adsorption capacity for gas N 2 The adsorption effect of O is much better than that of gas N 2 adsorption effect.

[0127] The products PI-1, PI-2 and PI-3 react with pure gas N 2 O and gas N 2 The adsorption isotherm of Figure 5a , Figure 5b as well as Figure 5c As shown in the figure, under 4MPa, products PI-1, PI-2 and PI-3 all showed resistance to N 2 O / N 2 The adsorption capacity of gas N 2 The adsorption of O is gas N 2 This indicates that the products PI-1, PI-2 and PI-3 all have excellent N 2 O / N 2 Separation ability, that is, the ability to separate gas N 2 OGood separation performance.

[0128] It can be seen from Tables 1 to 7 that the adsorption amounts of products PI-2, PI-6, PI-7, PI-8 and PI-9 are very different. At 298K and 4MPa pressure, the adsorption amounts of products PI-2, PI-6, PI-7, PI-8 and PI-9 are 6.93mmol / g, 7.48mmol / g, 7.18mmol / g, 8.60mmol / g and 9.09mmol / g, respectively, while for N 2 The adsorption amounts of PI-2, PI-6, PI-7, PI-8 and PI-9 were 0.74 mmol / g, 0.89 mmol / g, 0.67 mmol / g, 0.70 mmol / g and 0.94 mmol / g, respectively. 2 The adsorption of O is always higher than that of N 2 This indicates that the products PI-2, PI-6, PI-7, PI-8 and PI-9 have a significant effect on N 2 The adsorption affinity of O is significantly stronger than that of N 2 At the same time, it can be seen that N 2 The order of adsorption capacity of O is PI-9>PI-8>PI-6>PI-7>PI-2. It can be seen that the more the number of anhydride functional groups, the more the synthesized adsorbent is for N 2 The greater the adsorption capacity of O, the more nitrogen atoms are in the anhydride.2 In addition, the adsorbent compounded with fluorine-containing ionic liquid can make N 2 The O gas adsorption performance is improved.

[0129] Table 1: The product PI-1 has a maximum pressure of 4 MPa and a high pressure of N 2 O and N 2 The measured adsorption amount

[0130]

[0131] Table 2: Product PI-2 at the highest pressure of 4 MPa for N 2 O and N 2 The measured adsorption amount

[0132]

[0133] Table 3: The product PI-3 has a maximum pressure of 4 MPa and a high pressure of N 2 O and N 2 The measured adsorption amount

[0134]

[0135] Table 4: Product PI-6 at the highest pressure of 4 MPa for N 2 O and N 2 The measured adsorption amount

[0136]

[0137]

[0138] Table 5: Product PI-7 at the highest pressure of 4 MPa for N 2 O and N 2 The measured adsorption amount

[0139]

[0140] Table 6: Product PI-8 at the highest pressure of 4 MPa for N 2 O and N 2 The measured adsorption amount

[0141]

[0142] Table 7: Product PI-9 at the highest pressure of 4 MPa for N 2 O and N 2 The measured adsorption amount

[0143]

[0144]

[0145] (2) The products PI-1, PI-2, PI-6, PI-7, PI-8 and PI-9 have an effect on N 2 O / N 2 Analysis of Selective Effects

[0146] The Langmuir equation was used to fit the adsorption isotherms of the products PI-1, PI-2, PI-6, PI-7, PI-8 and PI-9, where the Langmuir equation is:

[0147]

[0148] Where: q—equilibrium adsorption capacity per unit volume (mmol / g), q m —saturated adsorption capacity per unit volume of adsorbent (mmol / g), p—equilibrium pressure (MPa), b—Langmuir constant (MPa -1 ). The Langmuir model can be used to fit the experimental data to obtain the relationship between N 2 O and N 2 separation selectivity.

[0149] (3) Calculation of separation coefficient of product PI-1 at different pressures

[0150] The Langmuir adsorption model was used to calculate the adsorption of different PI products on binary mixture components (N 2 O and N 2 In order to simulate the actual industrial production environment, the separation coefficient of N 2 O / N 2 Ratio, i.e. N 2 The binary mixed gas with an O content of 40% was analyzed and the separation coefficient was calculated at different pressures.

[0151] First, the product PI-1 was used to calculate the N at three different pressures: 1MPa, 2MPa, and 4MPa. 2 O / N 2 The selectivity varies with the molar ratio of gas components. Figure 6 As shown, N 2 O / N 2 The selectivity of the mixture increases with the N 2 The selectivity increases with the increase of O content, but the slopes of the three curves are different, indicating that the selectivity increases with the increase of N content in the component at 4 MPa. 2 The increase rate of O content is the fastest at 2MPa, followed by 1MPa. According to this rule, it can be seen that under higher pressure, as N 2 As the O mole fraction increases, the selectivity increases faster. 2O is more adsorbed on the sample than N 2 , which is more affected by the mixture composition and is more favorable to N 2 O / N 2 Among them, selectivity refers to the separation of two gas mixtures. If the adsorption performance of one gas is very high and the other is very low, it is easy to separate and has good separation selectivity. 2 O / N 2 The separation coefficient of binary gas mixture is investigated according to Figure 6 From the slopes of the three curves, it can be found that for the same material and other conditions, the separation factor increases with increasing pressure. 2 O / N 2 The separation factor is 59.60.

[0152] For PI-2, PI-6, PI-7, PI-8 and PI-9, N 2 O / N 2 Analysis of Selective Effects

[0153] N 2 The O content is 50% binary mixed gas, and the fitted data are shown in Table 8.

[0154] Table 8. Adsorption of 298K materials on N at 0-4 MPa pressure 2 O / N 2 Adsorption selectivity (YN 2 O=0.5)

[0155]

[0156] It can be seen that at 4 MPa pressure, PI-2, PI-6, PI-7, PI-8 and PI-9 have a significant effect on N 2 O / N 2 The selectivities are 10.5, 35.3, 71.9, 100.8, and 26.3 respectively.

[0157] It can be seen that the adsorbent synthesized by the present invention has a stable rigid structure, excellent thermal stability, rich and adjustable pore structure, and can be functionalized. That is, on the one hand, monomers with special groups that are basically consistent with the listed ones can be selected for synthesis, so that functionalized monomers can be directly obtained or chemical modification effects can be achieved. On the other hand, the synthesized material can be blended and modified with other polymers.

[0158] When using the nitrous oxide capture and separation adsorbent of the present invention for adsorption, the specific method is: accurately weigh a certain mass of the nitrous oxide capture and separation adsorbent, and place it in a dry, clean stainless steel reactor, which is not limited here, as long as it is a sealed container.2 O, i.e. the target gas mixture, is slowly injected into the container containing the nitrous oxide capture and separation adsorbent according to the set volume or pressure, so that the gas and the adsorbent are fully in contact. This process is carried out in a constant temperature water bath to keep the temperature constant, and the set temperature is 25°C.

[0159] When adsorbing the target gas, the gas and the adsorbent are fully in contact with each other and the process is controlled in a constant temperature environment to eliminate the interference of temperature on the adsorption process. It can also be carried out in a constant temperature box that can accurately control the temperature to keep the temperature constant. The set temperature can be determined according to actual research needs, such as 25°C or 30°C.

[0160] Then, the mixed gas was contacted with the adsorbent for at least 30 min to allow the adsorption to reach equilibrium state, and the equilibrium was maintained for 30 min.

[0161] In the above-mentioned equilibrium process, the equilibrium time is preferably 30 minutes to 2 hours. When the time is less than 30 minutes, a complete adsorption equilibrium state cannot be achieved. When the time is longer than 2 hours, there is not much effect on the adsorption equilibrium.

[0162] A gas chromatograph is used to measure the change in gas concentration before and after adsorption. The analytical testing instrument can also use a gas sensor to measure the change in gas concentration before and after adsorption, and based on relevant calculations (such as the adsorption amount calculation formula: adsorption amount = (initial gas concentration-gas concentration after adsorption) × gas volume ÷ polyimide sample mass), the adsorption amount of the gas by the nitrous oxide capture and separation adsorbent is obtained.

[0163] It can be seen that when the adsorbent provided by the present invention is used to adsorb N 2 When the mixed gas of O is used, the operation is relatively simple and convenient. It does not require complicated equipment to achieve operations such as continuous flow of gas, which is convenient for controlling experimental conditions and is very convenient for exploring the adsorption performance of different gases.

[0164] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not limitations on the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are still within the protection scope of the present invention.

Claims

1. A method for preparing a nitrous oxide capture and separation adsorbent, wherein: The preparation method comprises the following steps: In a protective gas atmosphere, an acid anhydride compound, a polyamine compound, a cross-linking agent and a catalyst are added to a reaction solvent to react; after the reaction is completed, a precipitate is obtained, separated, washed and dried to obtain the nitrous oxide capture and separation adsorbent; The acid anhydride compound is a compound containing two or more carboxylic anhydride functional groups; the polyamine compound is a compound containing two or more NH2 functional groups; the cross-linking agent is triaminopyrimidine; and the catalyst is isoquinoline.

2. The preparation method according to claim 1, wherein The acid anhydride compound is selected from one or a combination of two or more of 1,4,5,8-naphthalenetetracarboxylic anhydride, pyromellitic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 4,4'-oxydiphthalic anhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 1,2,3,4-butanetetracarboxylic dianhydride, mellitic acid trianhydride, terphenylene [2,3-c:6,7-c':10,11-c"]trifuran-1,3,6,8,11,13-hexaketone or hexaazatrimellitic acid trianhydride.

3. The preparation method according to claim 1, wherein The polyamine compound is selected from one or a combination of two or more of benzidine, tris(4-aminophenyl)amine, 1,3,5-tris(4-aminophenyl)benzene, 3,3'-diaminobenzidine, 4',5'-bis(4-aminophenyl)-[1,1':2',1"-terphenyl]-4,4"-diamine, tetrakis(4-aminophenyl)methane, N,N,N',N'-tetrakis(p-aminophenyl)p-phenylenediamine, hexa(4-aminohexaphenyl)benzene, 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, and 4',4"',4""'-(1,3,5-triazine-2,4,6-triyl)tris(([1,1'-biphenyl]-4-amine)).

4. The preparation method according to claim 1, wherein The triaminopyrimidine is selected from 2,4,6-triaminopyrimidine, 4,5,6-triaminopyrimidine or 2,4,5-triaminopyrimidine, or a combination of two or more thereof.

5. The preparation method according to claim 1, wherein The reaction solvent is selected from one or a combination of two or more of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, 1,3-dimethyl-2-imidazolidinone, 1,1,3-trimethylcyclohexenone, m-cresol, dodecane, diphenyl ether, cyclopentane, toluene, propylbenzene, mesitylene, and o-dichlorobenzene.

6. The preparation method according to claim 1, wherein The reaction temperature is 100-300° C. and the reaction time is 24-200 hours.

7. The preparation method according to claim 1, wherein The molar ratio of the total amount of the polyamine compound and the cross-linking agent to the acid anhydride is 1:(1-1.5); The molar ratio of the polyamine compound to the cross-linking agent is 1:(0.3-3); The molar ratio of the catalyst to the acid anhydride compound is (2.5-5):

1.

8. A nitrous oxide capture and separation adsorbent obtained by the preparation method according to any one of claims 1 to 7.

9. Use of the nitrous oxide capture and separation adsorbent according to claim 8 in capturing and separating N2O gas.

10. The use according to claim 9, wherein: Capturing and separating N2O gas from a mixed gas containing N2O; the mixed gas containing N2O is N2O / N2, N2O / H2 or N2O / CH4; Preferably, the temperature of the adsorption separation for capturing and separating the N2O gas is 298 to 313 K, and the pressure of the adsorption separation is 0 to 4 MPa; Preferably, the nitrous oxide capture and separation adsorbent is compounded with an ionic liquid; Preferably, the nitrous oxide capture and separation adsorbent and the ionic liquid are fully mixed, dried and then ground; Preferably, the ionic liquid is selected from one or a combination of two or more of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-butyl-3-methylimidazolium hexafluorophosphate, and 1-(3-aminopropyl)-3-methylimidazolium bromide; Preferably, the mass ratio of the nitrous oxide capture and separation adsorbent to the ionic liquid is 95:5.

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