Material for adsorbing, trapping and recycling high-concentration nitrogen oxide and preparation method thereof

Abstract

The invention discloses a material for adsorbing, trapping and recycling high-concentration nitric oxide and a preparation method of the material. The material for adsorbing, trapping and recycling the high-concentration nitric oxide is a nickel ion modified ZSM-5 zeolite molecular sieve with a high silica-alumina ratio. The material for adsorbing, trapping and recycling the high-concentration nitric oxide can be suitable for tail gas treated in the nuclear industry, has NO catalytic oxidation capacity and hydrophobicity, and can prevent CO2 from forming competitive adsorption on NO2, and the treatment efficiency is improved. The silica-alumina ratio is high, so that the hydrophobicity of the adsorbent can be improved, and meanwhile, a certain amount of Al ions can catalyze NO into NO2. The nickel ions have the effects that the nickel ions and NO2 / N2O4 form supramolecular interaction in a confined space, selective reversible adsorption of NO2 is realized under the synergistic effect of multi-site Van der Waals force, regeneration of the adsorbent is promoted, and NO2 is desorbed and recovered, and nitrogen oxide molecules play an important role in diffusion in pore channels of the molecular sieve.

Description

Technical Field

[0001] The invention belongs to the technical field of spent fuel post-processing, and particularly relates to a material for adsorption, capture and recovery of high-concentration nitrogen oxides and a preparation method thereof. Background Art

[0002] With the continuous expansion of nuclear power, in order to achieve safe management of spent fuel and waste minimization in nuclear power plants, improve the utilization rate of uranium resources, and ensure the sustainable development of nuclear energy, we must adhere to the closed cycle of nuclear fuel based on advanced reprocessing technology.

[0003] If spent fuel NOx is not recycled and discharged directly, the nitrogen oxides (such as NO2) in NOx will react with water in the atmosphere to produce nitric acid and nitrous acid, which will form acid rain and damage the soil, water bodies and vegetation. NOx treatment can effectively reduce the risk of acid rain formation.

[0004] NOx will undergo photochemical reactions with hydrocarbons under sunlight to produce harmful chemicals such as ozone and peroxyacetyl nitrate, forming photochemical smog. NOx treatment helps reduce the occurrence of photochemical smog.

[0005] NOx emissions can also affect plant growth, reduce crop yield and quality, and damage the living environment of wild animals. NOx treatment is beneficial to protecting ecosystem balance and biodiversity.

[0006] Nitrogen dioxide (NO2) is the preferred oxidant in post-processing processes and a decomposer for hydrazine. However, the current production cost of NO2 is high and it causes serious pollution. Therefore, upgrading the post-processing technology system is of great significance in promoting the sustainable development of the nuclear energy industry. By recovering NO2 from spent fuel exhaust and realizing its resource utilization, it complies with the principle of minimizing green chemical waste and is expected to achieve an in-plant nitrogen economic cycle.

[0007] Currently, there is no adsorption material for the adsorption of high-concentration NOx in the nuclear industry, and the ZSM-5 molecular sieve used in civilian chemical industry cannot be used for the adsorption and purification of high-concentration NOx in the nuclear industry. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to address the above-mentioned deficiencies in the prior art and provide a material for the adsorption, capture and recovery of high-concentration nitrogen oxides and a preparation method thereof. The material of the present invention has NO catalytic oxidation ability, hydrophobicity and can avoid competitive adsorption of CO2 on NO2, thereby improving treatment efficiency.

[0009] The technical solution adopted to solve the technical problem of the present invention is to provide a material for adsorption, capture and recovery of high-concentration nitrogen oxides, which is a nickel ion-modified high-silicon-aluminum ratio ZSM-5 zeolite molecular sieve.

[0010] Preferably, the high silicon-to-aluminum ratio of the ZSM-5 zeolite molecular sieve is 200-500.

[0011] Preferably, the ZSM-5 zeolite molecular sieve is represented by xNaOH·yC4H 16 N2·(z / 300)NaAlO2·zSiO2·wH2O, wherein x is 3-4; y is 2-3; z is 5-8; and w is 10-12.

[0012] The present invention provides a method for preparing the above-mentioned material for adsorption, capture and recovery of high-concentration nitrogen oxides, comprising the following steps:

[0013] The ZSM-5 zeolite molecular sieve with a high silicon-aluminum ratio is modified with a nickel ion solution to obtain a material for the adsorption, capture and recovery of high-concentration nitrogen oxides.

[0014] Preferably, the method for preparing the material for the adsorption, capture and recovery of high-concentration nitrogen oxides further comprises the following steps: preparing a ZSM-5 zeolite molecular sieve with a high silicon-aluminum ratio.

[0015] Preferably, the step of preparing the ZSM-5 zeolite molecular sieve with a high silicon-aluminum ratio is as follows:

[0016] The following steps are involved:

[0017] (1) Preparation of materials: silica sol, sodium aluminate, sodium hydroxide, 1,6-hexanediamine, and anhydrous ethanol;

[0018] (2) mixing the raw materials in step (1) to obtain a mixed solution;

[0019] (3) subjecting the obtained mixed solution to crystallization treatment;

[0020] (4) After crystallization, the mixture is cooled, washed, and dried to obtain a ZSM-5 zeolite molecular sieve with a high silicon-aluminum ratio.

[0021] Preferably, the molar ratio of silica sol, sodium aluminate, sodium hydroxide and 1,6-hexanediamine in step (1) is x:y:(z / 300):z, wherein x is 3-4; y is 2-3; and z is 5-8.

[0022] Preferably, the mixing time of step (2) is 20 to 40 minutes, and the mixing is carried out by stirring at a stirring speed of 1000 to 1400 r / min.

[0023] Preferably, the crystallization treatment temperature in step (3) is 165-168° C., and the crystallization treatment time is 3-4 days.

[0024] Preferably, the washing in step (4) is: repeatedly rinsing with water for 10 to 30 minutes.

[0025] Preferably, the drying in step (4) is specifically carried out at a temperature of 102-105° C. for 2-3 hours.

[0026] Preferably, the nickel ion modification treatment of the high silicon-aluminum ratio ZSM-5 zeolite molecular sieve comprises the following steps:

[0027] Prepare nickel ion treatment solution;

[0028] The ZSM-5 zeolite molecular sieve with a high silicon-aluminum ratio is mixed with a nickel ion treatment solution, and then subjected to vacuum impregnation treatment, and then filtered, dried, and calcined to obtain a modified ZSM-5 zeolite molecular sieve with a high silicon-aluminum ratio.

[0029] Preferably, the concentration of nickel ions in the prepared nickel ion treatment solution is 1-1.5 mol / L.

[0030] Preferably, the temperature of the vacuum impregnation treatment is 70-80° C., the time is 10-12 hours, and the vacuum degree is 0.1-0.3 Pa.

[0031] Preferably, the drying temperature after the vacuum impregnation treatment is 110 to 115° C., and the drying time is 1 to 3 hours.

[0032] Preferably, the calcination temperature after the vacuum impregnation treatment is 620-630° C., the time is 4-6 hours, and the calcination atmosphere is air atmosphere.

[0033] Preferably, the nickel ion content in the modified high silicon-aluminum ratio ZSM-5 zeolite molecular sieve is 1.8 to 2.1 mmol / g.

[0034] The material prepared by the present invention for the adsorption, capture and recovery of high-concentration nitrogen oxides can be applied to tail gas treated by the nuclear industry. The material of the present invention has NO catalytic oxidation ability, hydrophobicity and can avoid the competitive adsorption of CO2 on NO2, thereby improving the treatment efficiency.

[0035] A high silicon-aluminum ratio can improve the hydrophobicity of the adsorbent, and a certain amount of Al ions can catalyze NO to NO2.

[0036] In order to avoid competitive adsorption of CO2, based on the -complexation interaction between transition metal ions and -bond (i.e., NO2) molecules, the present invention developed transition metal ion (nickel ion) exchange zeolite as a NO2 adsorbent. The high NO2 selectivity is related to the high interaction strength of π complexation, which is achieved by changing the type and valence of cations and the topological structure of the zeolite.

[0037] In addition, the role of metal cations (nickel ions) is to form supramolecular interactions with NO2 / N2O4 in a confined space, creating selective reversible adsorption of NO2 under the synergistic action of multi-site van der Waals forces, thereby promoting adsorbent regeneration and desorbed gas NO2 recovery.

[0038] In the adsorption process of the present invention, the diffusion of nitrogen oxide molecules in the pores of the zeolite molecular sieve also plays an important role. The suitable pore structure thereof can promote the diffusion of nitrogen oxide molecules, making it easier for them to reach the adsorption sites and be adsorbed. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a statistical graph of the NOx breakthrough adsorption amount in each group in Examples 1 to 4 and Comparative Examples 1 to 4. DETAILED DESCRIPTION

[0040] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0041] The present invention provides a material for adsorption, capture and recovery of high-concentration nitrogen oxides in a post-processing plant, which is a nickel-ion-modified ZSM-5 zeolite molecular sieve with a high silicon-aluminum ratio.

[0042] The present invention provides a method for preparing the above-mentioned material for adsorption, capture and recovery of high-concentration nitrogen oxides in a post-processing plant, comprising the following steps:

[0043] The ZSM-5 zeolite molecular sieve with a high silicon-aluminum ratio is modified with a nickel ion solution to obtain a material for the adsorption, capture and recovery of high-concentration nitrogen oxides in a post-processing plant.

[0044] The material prepared by the present invention for the adsorption, capture and recovery of high-concentration nitrogen oxides in post-processing plants can be applied to tail gas treated by the nuclear industry. The material of the present invention has NO catalytic oxidation ability, hydrophobicity and can avoid the competitive adsorption of CO2 on NO2, thereby improving the treatment efficiency.

[0045] Example 1

[0046] This embodiment provides a material for the adsorption, capture and recovery of high-concentration nitrogen oxides in a post-processing plant, which is a nickel-ion-modified ZSM-5 zeolite molecular sieve with a high silicon-aluminum ratio.

[0047] Preferably, the high silicon-to-aluminum ratio of the ZSM-5 zeolite molecular sieve is 200-500.

[0048] Preferably, the ZSM-5 zeolite molecular sieve is represented by xNaOH·yC4H 16 N2·(z / 300)NaAlO2·zSiO2·wH2O, wherein x is 3-4; y is 2-3; z is 5-8; and w is 10-12.

[0049] This embodiment provides a method for preparing the above-mentioned material for the adsorption, capture and recovery of high-concentration nitrogen oxides in a post-processing plant, comprising the following steps:

[0050] The ZSM-5 zeolite molecular sieve with a high silicon-aluminum ratio is modified with a nickel ion solution to obtain a material for the adsorption, capture and recovery of high-concentration nitrogen oxides in a post-processing plant.

[0051] Preferably, the method for preparing the material for the adsorption, capture and recovery of high-concentration nitrogen oxides in a post-processing plant further comprises the following steps: preparing a ZSM-5 zeolite molecular sieve with a high silicon-aluminum ratio.

[0052] Preferably, the step of preparing the ZSM-5 zeolite molecular sieve with a high silicon-aluminum ratio specifically comprises the following steps:

[0053] (1) Preparation of materials: silica sol, sodium aluminate, sodium hydroxide, 1,6-hexanediamine, and anhydrous ethanol;

[0054] (2) mixing the above raw materials to obtain a mixed solution;

[0055] (3) subjecting the obtained mixed solution to crystallization treatment;

[0056] (4) After crystallization, the mixture is cooled, washed, and dried to obtain a ZSM-5 zeolite molecular sieve with a high silicon-aluminum ratio.

[0057] Preferably, the molar ratio of silica sol, sodium aluminate, sodium hydroxide and 1,6-hexanediamine in step (1) is x:y:(z / 300):z, wherein x is 3-4; y is 2-3; and z is 5-8.

[0058] Preferably, the mixing time of step (2) is 20 to 40 minutes, and the mixing is carried out by stirring at a stirring speed of 1000 to 1400 r / min.

[0059] Preferably, the crystallization treatment temperature in step (3) is 165-168° C. and the crystallization treatment time is 3-4 days. Carrying out the crystallization treatment in this temperature range can increase the crystallinity and improve the crystallinity and particle size uniformity of the molecular sieve.

[0060] Preferably, the washing in step (4) is performed by repeatedly rinsing with water for 10 to 30 minutes, the main purpose of which is to remove unreacted soluble impurities.

[0061] Preferably, the drying in step (4) is carried out at a temperature of 102-105° C. for 2-3 hours. Drying at this temperature is more efficient. Too low a drying temperature will significantly increase the drying time, while too high a drying temperature will negatively affect the structure.

[0062] Preferably, the nickel ion modification treatment of the high silicon-aluminum ratio ZSM-5 zeolite molecular sieve comprises the following steps:

[0063] Prepare nickel ion treatment solution;

[0064] The ZSM-5 zeolite molecular sieve with a high silicon-aluminum ratio is mixed with a nickel ion treatment solution, and then subjected to vacuum impregnation treatment, and then filtered, dried, and calcined to obtain a modified ZSM-5 zeolite molecular sieve with a high silicon-aluminum ratio.

[0065] Preferably, the nickel ion concentration in the nickel ion treatment solution is 1-1.5 mol / L. Within this concentration range, a higher cationic modification efficiency can be achieved.

[0066] Preferably, the temperature of the vacuum impregnation treatment is 70-80° C., the time is 10-12 hours, and the vacuum degree is 0.1-0.3 Pa.

[0067] In this temperature range, the uniformity of the combination of ZSM-5 zeolite molecular sieve and metal cations (nickel ions) can be improved. In this vacuum range, the dispersion of metal cations can be improved, promoting the combination of the two.

[0068] Preferably, the drying temperature after vacuum impregnation is 110-115°C for 1-3 hours. Drying at this temperature is more efficient. Too low a drying temperature will significantly increase the drying time, while too high a drying temperature will negatively affect the structure.

[0069] Preferably, the calcination temperature after vacuum impregnation is 620-630°C for 4-6 hours in an air atmosphere. Calcination in this temperature range can improve calcination efficiency, produce a more stable molecular sieve, and effectively remove impurities, thereby improving the stability of the binding between metal cations (nickel ions) and the molecular sieve.

[0070] Preferably, the nickel ion content in the modified high-silicon-aluminum ratio ZSM-5 zeolite molecular sieve is 1.8 to 2.1 mmol / g. At this nickel ion content, it can exhibit a higher degree of supermolecular interaction with NO2 / N2O4 within a confined space, creating selective and reversible NO2 adsorption under the synergistic action of multi-site van der Waals forces, thereby promoting adsorbent regeneration and desorbed NO2 recovery. Excessively high or low nickel ion content will affect adsorbent regeneration and desorption.

[0071] Specifically, this embodiment provides a material for adsorption, capture and recovery of high-concentration nitrogen oxides (NOx) in a post-processing plant, which is a nickel-ion-modified high-silicon-to-aluminum ZSM-5 zeolite molecular sieve. The high silicon-to-aluminum ratio of the ZSM-5 zeolite molecular sieve is 300.

[0072] The method for preparing the material for the adsorption, capture and recovery of high-concentration nitrogen oxides in a post-processing plant in this embodiment comprises the following steps:

[0073] Preparation of ZSM-5 zeolite molecular sieve with high silicon-aluminum ratio;

[0074] The ZSM-5 zeolite molecular sieve with a high silicon-aluminum ratio is modified with a nickel ion solution to obtain a material for the adsorption, capture and recovery of high-concentration nitrogen oxides in a post-processing plant.

[0075] Among them, the preparation method of ZSM-5 zeolite molecular sieve with high silicon-aluminum ratio is:

[0076] (1) Preparation of materials: silica sol, sodium aluminate, sodium hydroxide, 1,6-hexanediamine, and anhydrous ethanol;

[0077] (2) Add the above raw materials into the reactor in sequence and stir at high speed for 30 minutes to obtain a mixed solution. The amount of each raw material is:

[0078] The silicon-aluminum ratio of the raw material is 300, xNaOH·yC4H 16 N2·(z / 300)NaAlO2·zSiO2·wH2O;

[0079] Where x is 3;

[0080] y is 2;

[0081] z is 5;

[0082] w is 10.

[0083] The high-speed stirring speed is 1200r / min;

[0084] (3) The obtained mixed solution was added to a crystallization container and crystallized at a constant temperature; the crystallization temperature was 165° C. and the crystallization time was 3 days.

[0085] (4) After the crystallization is completed, it is cooled, washed, and dried; the drying step is: drying at 102°C for 2 hours; the washing step is: rinsing repeatedly with room temperature water for 20 minutes;

[0086] Among them, the specific method of metal cation modification treatment is:

[0087] Prepare metal cation treatment solution;

[0088] Mix the high silicon-aluminum ratio ZSM-5 zeolite molecular sieve with the metal cation treatment solution, add it to the vacuum impregnation reactor, and then perform vacuum impregnation treatment for 10 hours, followed by filtration, drying, and calcination.

[0089] The vacuum impregnation temperature is 70°C;

[0090] The vacuum degree of vacuum impregnation is 0.1Pa;

[0091] The drying temperature is 110°C and the drying time is 2 hours;

[0092] The calcination temperature is 620°C and the time is 5 hours;

[0093] Wherein, the calcination atmosphere is air atmosphere;

[0094] The metal cation content in the modified high silicon-aluminum ratio ZSM-5 zeolite molecular sieve is:

[0095] 2.1mmol / g.

[0096] Wherein, the preparation method of metal cation treatment solution is:

[0097] First, nickel nitrate is added to deionized water and stirred to mix well to obtain metal cation treatment;

[0098] The nickel ion concentration in the metal cation treatment solution is 1 mol / L.

[0099] The material for adsorption, capture and recovery of high-concentration nitrogen oxides in a post-processing plant in this embodiment is applied to adsorption, capture and recovery of high-concentration NOx in a post-processing plant.

[0100] The primary selection of NO2 adsorbent is mainly based on two principles:

[0101] 1) The main pore diameter of the adsorbent is larger than the NO2 kinetic diameter (~0.34nm);

[0102] 2) The adsorption space has a suitable size, which can promote the dimerization of NO2 in the pores to form N2O4 with a larger molecular volume, such as zeolites with more than ten-membered rings. The present invention selects MFI type ZSM-5 molecular sieve as the initial material and performs metal cation modification to obtain a material for the adsorption, capture and recovery of high-concentration NOx in post-treatment plants.

[0103] The material prepared in this embodiment for the adsorption, capture and recovery of high-concentration nitrogen oxides in post-processing plants can be applied to exhaust gases treated by the nuclear industry. The material in this embodiment has NO catalytic oxidation ability, hydrophobicity and can avoid competitive adsorption of CO2 on NO2, thereby improving treatment efficiency.

[0104] Through a large number of tests with various silicon-aluminum ratios, it was found that a silicon-aluminum ratio of 300 is the best adsorption material. This is because a higher silicon-aluminum ratio can increase the hydrophobicity of the adsorbent, and a certain amount of Al ions can catalyze NO to NO2.

[0105] In order to avoid competitive adsorption of CO2, based on the -complexation interaction between transition metal ions and -bond (i.e., NO2) molecules, this embodiment developed a transition metal ion (nickel ion) exchange zeolite as a NO2 adsorbent. The high NO2 selectivity is related to the high interaction strength of π complexation, which is achieved by changing the type and valence of cations and the topological structure of the zeolite.

[0106] In addition, the role of metal cations (nickel ions) is to form supramolecular interactions with NO2 / N2O4 in a confined space, creating selective reversible adsorption of NO2 under the synergistic action of multi-site van der Waals forces, thereby promoting adsorbent regeneration and desorbed gas NO2 recovery.

[0107] In the adsorption process of this embodiment, the diffusion of nitrogen oxide molecules in the pores of the zeolite molecular sieve also plays an important role. The suitable pore structure thereof can promote the diffusion of nitrogen oxide molecules, making it easier for them to reach the adsorption sites and be adsorbed.

[0108] Example 2

[0109] This embodiment provides a material for the adsorption, capture and recovery of high-concentration nitrogen oxides (NOx) in a post-processing plant, which is a nickel-ion-modified high-silicon-to-aluminum ZSM-5 zeolite molecular sieve. The high silicon-to-aluminum ratio of the ZSM-5 zeolite molecular sieve is 250.

[0110] The method for preparing the material for the adsorption, capture and recovery of high-concentration nitrogen oxides in a post-processing plant in this embodiment comprises the following steps:

[0111] Preparation of ZSM-5 zeolite molecular sieve with high silicon-aluminum ratio;

[0112] The ZSM-5 zeolite molecular sieve with a high silicon-aluminum ratio is modified with a nickel ion solution to obtain a material for the adsorption, capture and recovery of high-concentration nitrogen oxides in a post-processing plant.

[0113] Among them, the preparation method of ZSM-5 zeolite molecular sieve with high silicon-aluminum ratio is:

[0114] (1) Preparation of materials: silica sol, sodium aluminate, sodium hydroxide, 1,6-hexanediamine, and anhydrous ethanol;

[0115] (2) Add the above raw materials into the reactor in sequence and stir at high speed for 30 minutes to obtain a mixed solution. The amount of each raw material is:

[0116] The silicon-aluminum ratio of the raw material is 250, xNaOH·yC4H 16 N2·(z / 300)NaAlO2·zSiO2·wH2O;

[0117] Where x is 3.5;

[0118] y is 2;

[0119] z is 6;

[0120] w is 11.

[0121] The high-speed stirring speed is 1200r / min;

[0122] (3) The obtained mixed solution was added to a crystallization container and crystallized at a constant temperature; the crystallization temperature was 167° C. and the crystallization time was 3 days.

[0123] (4) After the crystallization is completed, it is cooled, washed, and dried; the drying step is: drying at 105°C for 2 hours; the washing step is: rinsing repeatedly with room temperature water for 10 minutes;

[0124] Among them, the specific method of metal cation modification treatment is:

[0125] Prepare metal cation treatment solution;

[0126] Mix the high silicon-aluminum ratio ZSM-5 zeolite molecular sieve with the metal cation treatment solution, add it to the vacuum impregnation reactor, and then perform vacuum impregnation treatment for 12 hours, followed by filtration, drying, and calcination.

[0127] The vacuum impregnation temperature is 75°C;

[0128] The vacuum degree of vacuum impregnation is 0.2Pa;

[0129] The drying temperature is 113°C and the drying time is 2 hours;

[0130] The calcination temperature is 6240°C and the time is 5 hours;

[0131] Wherein, the calcination atmosphere is air atmosphere;

[0132] The metal cation content in the modified high silicon-aluminum ratio ZSM-5 zeolite molecular sieve is:

[0133] 1.9mmol / g.

[0134] Wherein, the preparation method of metal cation treatment solution is:

[0135] First, nickel nitrate is added to deionized water and stirred to mix well to obtain metal cation treatment;

[0136] The nickel ion concentration in the metal cation treatment solution is 1 mol / L.

[0137] The material for adsorption, capture and recovery of high-concentration nitrogen oxides in a post-processing plant in this embodiment is applied to adsorption, capture and recovery of high-concentration NOx in a post-processing plant.

[0138] The primary selection of NO2 adsorbent is mainly based on two principles:

[0139] 1) The main pore diameter of the adsorbent is larger than the NO2 kinetic diameter (~0.34nm);

[0140] 2) The adsorption space has a suitable size, which can promote the dimerization of NO2 in the pores to form N2O4 with a larger molecular volume, such as zeolites with more than ten-membered rings. The present invention selects MFI type ZSM-5 molecular sieve as the initial material and performs metal cation modification to obtain a material for the adsorption, capture and recovery of high-concentration NOx in post-treatment plants.

[0141] The material prepared in this embodiment for the adsorption, capture and recovery of high-concentration nitrogen oxides in post-processing plants can be applied to exhaust gases treated by the nuclear industry. The material in this embodiment has NO catalytic oxidation ability, hydrophobicity and can avoid competitive adsorption of CO2 on NO2, thereby improving treatment efficiency.

[0142] A high silicon-aluminum ratio can improve the hydrophobicity of the adsorbent, and a certain amount of Al ions can catalyze NO to NO2.

[0143] In order to avoid competitive adsorption of CO2, based on the -complexation interaction between transition metal ions and -bond (i.e., NO2) molecules, this embodiment developed a transition metal ion (nickel ion) exchange zeolite as a NO2 adsorbent. The high NO2 selectivity is related to the high interaction strength of π complexation, which is achieved by changing the type and valence of cations and the topological structure of the zeolite.

[0144] In addition, the role of metal cations (nickel ions) is to form supramolecular interactions with NO2 / N2O4 in a confined space, creating selective reversible adsorption of NO2 under the synergistic action of multi-site van der Waals forces, thereby promoting adsorbent regeneration and desorbed gas NO2 recovery.

[0145] In the adsorption process of this embodiment, the diffusion of nitrogen oxide molecules in the pores of the zeolite molecular sieve also plays an important role. The suitable pore structure thereof can promote the diffusion of nitrogen oxide molecules, making it easier for them to reach the adsorption sites and be adsorbed.

[0146] Example 3

[0147] This embodiment provides a material for adsorption, capture and recovery of high-concentration nitrogen oxides (NOx) in a post-processing plant, which is a nickel-ion-modified high-silicon-to-aluminum ZSM-5 zeolite molecular sieve. The high silicon-to-aluminum ratio of the ZSM-5 zeolite molecular sieve is 450.

[0148] The method for preparing the material for the adsorption, capture and recovery of high-concentration nitrogen oxides in a post-processing plant in this embodiment comprises the following steps:

[0149] Preparation of ZSM-5 zeolite molecular sieve with high silicon-aluminum ratio;

[0150] The ZSM-5 zeolite molecular sieve with a high silicon-aluminum ratio is modified with a nickel ion solution to obtain a material for the adsorption, capture and recovery of high-concentration nitrogen oxides in a post-processing plant.

[0151] Among them, the preparation method of ZSM-5 zeolite molecular sieve with high silicon-aluminum ratio is:

[0152] (1) Preparation of materials: silica sol, sodium aluminate, sodium hydroxide, 1,6-hexanediamine, and anhydrous ethanol;

[0153] (2) Add the above raw materials into the reactor in sequence and stir at high speed for 20 minutes to obtain a mixed solution. The amount of each raw material is:

[0154] The silicon-aluminum ratio of the raw material is 450, xNaOH·yC4H 16 N2·(z / 300)NaAlO2·zSiO2·wH2O;

[0155] Where x is 4;

[0156] y is 3;

[0157] z is 8;

[0158] w is 12.

[0159] The high-speed stirring speed is 1000r / min;

[0160] (3) The obtained mixed solution was added to a crystallization container and crystallized at a constant temperature; the crystallization temperature was 168° C. and the crystallization time was 4 days.

[0161] (4) After the crystallization is completed, it is cooled, washed, and dried; the drying step is: drying at 104°C for 3 hours; the washing step is: rinsing repeatedly with room temperature water for 30 minutes;

[0162] Among them, the specific method of metal cation modification treatment is:

[0163] Prepare metal cation treatment solution;

[0164] Mix the high silicon-aluminum ratio ZSM-5 zeolite molecular sieve with the metal cation treatment solution, add it to the vacuum impregnation reactor, and then perform vacuum impregnation treatment for 12 hours, followed by filtration, drying, and calcination.

[0165] The vacuum impregnation temperature is 80°C;

[0166] The vacuum degree of vacuum impregnation is 0.3Pa;

[0167] The drying temperature is 115°C and the drying time is 2 hours;

[0168] The calcination temperature is 630°C and the time is 4 hours;

[0169] Wherein, the calcination atmosphere is air atmosphere;

[0170] The metal cation content in the modified high silicon-aluminum ratio ZSM-5 zeolite molecular sieve is:

[0171] 2.0mmol / g.

[0172] Wherein, the preparation method of metal cation treatment solution is:

[0173] First, nickel nitrate is added to deionized water and stirred to mix well to obtain metal cation treatment;

[0174] The nickel ion concentration in the metal cation treatment solution is 1.5 mol / L.

[0175] The material for adsorption, capture and recovery of high-concentration nitrogen oxides in a post-processing plant in this embodiment is applied to adsorption, capture and recovery of high-concentration NOx in a post-processing plant.

[0176] The primary selection of NO2 adsorbent is mainly based on two principles:

[0177] 1) The main pore diameter of the adsorbent is larger than the NO2 kinetic diameter (~0.34nm);

[0178] 2) The adsorption space has a suitable size, which can promote the dimerization of NO2 in the pores to form N2O4 with a larger molecular volume, such as zeolites with more than ten-membered rings. The present invention selects MFI type ZSM-5 molecular sieve as the initial material and performs metal cation modification to obtain a material for the adsorption, capture and recovery of high-concentration NOx in post-treatment plants.

[0179] The material prepared in this embodiment for the adsorption, capture and recovery of high-concentration nitrogen oxides in post-processing plants can be applied to exhaust gases treated by the nuclear industry. The material in this embodiment has NO catalytic oxidation ability, hydrophobicity and can avoid competitive adsorption of CO2 on NO2, thereby improving treatment efficiency.

[0180] A high silicon-aluminum ratio can improve the hydrophobicity of the adsorbent, and a certain amount of Al ions can catalyze NO to NO2.

[0181] In order to avoid competitive adsorption of CO2, based on the -complexation interaction between transition metal ions and -bond (i.e., NO2) molecules, this embodiment developed a transition metal ion (nickel ion) exchange zeolite as a NO2 adsorbent. The high NO2 selectivity is related to the high interaction strength of π complexation, which is achieved by changing the type and valence of cations and the topological structure of the zeolite.

[0182] In addition, the role of metal cations (nickel ions) is to form supramolecular interactions with NO2 / N2O4 in a confined space, creating selective reversible adsorption of NO2 under the synergistic action of multi-site van der Waals forces, thereby promoting adsorbent regeneration and desorbed gas NO2 recovery.

[0183] In the adsorption process of this embodiment, the diffusion of nitrogen oxide molecules in the pores of the zeolite molecular sieve also plays an important role. The suitable pore structure thereof can promote the diffusion of nitrogen oxide molecules, making it easier for them to reach the adsorption sites and be adsorbed.

[0184] Example 4

[0185] This embodiment provides a material for the adsorption, capture and recovery of high-concentration nitrogen oxides (NOx) in a post-processing plant, which is a nickel-ion-modified high-silicon-to-aluminum ZSM-5 zeolite molecular sieve. The high silicon-to-aluminum ratio of the ZSM-5 zeolite molecular sieve is 500.

[0186] The method for preparing the material for the adsorption, capture and recovery of high-concentration nitrogen oxides in a post-processing plant in this embodiment comprises the following steps:

[0187] Preparation of ZSM-5 zeolite molecular sieve with high silicon-aluminum ratio;

[0188] The ZSM-5 zeolite molecular sieve with a high silicon-aluminum ratio is modified with a nickel ion solution to obtain a material for the adsorption, capture and recovery of high-concentration nitrogen oxides in a post-processing plant.

[0189] Among them, the preparation method of ZSM-5 zeolite molecular sieve with high silicon-aluminum ratio is:

[0190] (1) Preparation of materials: silica sol, sodium aluminate, sodium hydroxide, 1,6-hexanediamine, and anhydrous ethanol;

[0191] (2) The above raw materials were added to the reactor in sequence and stirred at high speed for 40 minutes to obtain a mixed solution. The amount of each raw material was as follows:

[0192] The silicon-aluminum ratio of the raw material is 500, xNaOH·yC4H 16 N2·(z / 300)NaAlO2·zSiO2·wH2O;

[0193] Where x is 3.6;

[0194] y is 2.8;

[0195] z is 7;

[0196] w is 11.

[0197] The high-speed stirring speed is 1400r / min;

[0198] (3) The obtained mixed solution was added to a crystallization container and crystallized at a constant temperature; the crystallization temperature was 166° C. and the crystallization time was 3.5 days.

[0199] (4) After the crystallization is completed, it is cooled, washed, and dried; the drying step is: drying at 103°C for 3 hours; the washing step is: rinsing repeatedly with room temperature water for 25 minutes;

[0200] Among them, the specific method of metal cation modification treatment is:

[0201] Prepare metal cation treatment solution;

[0202] Mix the high silicon-aluminum ratio ZSM-5 zeolite molecular sieve with the metal cation treatment solution, add it to the vacuum impregnation reactor, and then perform vacuum impregnation treatment for 11 hours, followed by filtration, drying, and calcination.

[0203] The vacuum impregnation temperature is 72°C;

[0204] The vacuum degree of vacuum impregnation is 0.2Pa;

[0205] The drying temperature is 114°C and the drying time is 2 hours;

[0206] The calcination temperature is 626°C and the time is 6 hours;

[0207] Wherein, the calcination atmosphere is air atmosphere;

[0208] The metal cation content in the modified high silicon-aluminum ratio ZSM-5 zeolite molecular sieve is:

[0209] 1.8mmol / g.

[0210] Wherein, the preparation method of metal cation treatment solution is:

[0211] First, nickel nitrate is added to deionized water and stirred to mix well to obtain metal cation treatment;

[0212] The nickel ion concentration in the metal cation treatment solution is 1.2 mol / L.

[0213] Comparative Example 1: This comparative example is basically the same as Example 2, except that the ZSM-5 zeolite molecular sieve with a high silicon-aluminum ratio is not subjected to metal cation modification treatment.

[0214] Comparative Example 2: This comparative example is basically the same as Example 2, except that vacuum impregnation is replaced by room temperature impregnation.

[0215] Comparative Example 3: This comparative example is basically the same as Example 2, except that the metal cation treatment solution is replaced by a copper nitrate ion solution with the same concentration.

[0216] Comparative Example 4: This comparative example is basically the same as Example 2, except that the metal cation treatment solution is replaced by a cobalt nitrate ion solution with the same concentration.

[0217] test:

[0218] Test exhaust gas: 3% NO, 6% NO2, 6% CO2, 2000ppm water;

[0219] Equal amounts of the example and comparative example materials were used for adsorption treatment:

[0220] The test experimental conditions are as follows: adsorption temperature is 50℃, inlet air flow rate is 25L / min; desorption temperature is 50℃, purge air flow rate is 2L / min, and desorption pressure is -95kPa.

[0221] Table 1

[0222] NOx breakthrough adsorption capacity mmol / g Example 1 1.53 Example 2 1.49 Example 3 1.51 Example 4 1.47 Comparative Example 1 0.98 Comparative Example 2 1.12 Comparative Example 3 1.29 Comparative Example 4 1.20

[0223] Through Table 1, Figure 1 It can be seen that the material prepared in the present invention can effectively improve the adsorption performance for NOx.

[0224] Based on the sample in Example 1, the effects of different intake air flow rates on NOx adsorption were compared for 1 hour:

[0225] Test exhaust gas: 3% NO, 6% NO2, 6% CO2, 2000ppm water;

[0226] The test experimental conditions are: adsorption temperature of 50°C, air flow rate of 10-50 L / min (preferably 25 L / min); desorption temperature of 50°C, purge gas flow rate of 2 L / min, and desorption pressure of -95 kPa, as shown in Table 2:

[0227] Table 2

[0228]

[0229] It can be seen from Table 2 that different intake air flow rates have a significant impact on the adsorption performance of the material. When the intake air flow rate is 25 L / min, the material of the present invention can achieve the maximum efficiency in adsorbing NOx.

[0230] Taking Example 1 as the basic sample, the effects of different silicon-aluminum ratios on the adsorption performance of the material are compared:

[0231] Table 3

[0232]

[0233]

[0234] It can be seen from Table 3 that the material made with a silicon-aluminum ratio of 300 has the best adsorption performance; by changing the silicon-aluminum ratio to 60, 120, 300, 600, and 1200 (the penetration adsorption amounts are 0.55, 0.73, 1.53, 0.93, and 0.81 mmol / g, respectively), it is found that the silicon-aluminum ratio of 300 is the best adsorbent. This is because a higher silicon-aluminum ratio can improve the hydrophobicity of the adsorbent, and a certain amount of Al ions can catalyze NO to NO2. However, an excessively high silicon-aluminum ratio will reduce the adsorption performance.

[0235] Test exhaust gas a: 3% NO, 6% NO2, 2000ppm water;

[0236] Test exhaust gas b: 3% NO, 6% NO2, 6% CO2, 2000ppm water;

[0237] Equal amounts of the materials from Example 1 were used for adsorption treatment:

[0238] The test experimental conditions are as follows: adsorption temperature is 50℃, inlet air flow rate is 25L / min; desorption temperature is 50℃, purge air flow rate is 2L / min, and desorption pressure is -95kPa.

[0239] Table 4 NOx breakthrough adsorption capacity mmol / g Test exhaust gas a 1.55 Test exhaust gas b 1.53

[0240] It can be seen from Table 4 that the adsorption amount of the raw gas remains basically unchanged when CO2 is added, which proves that the high selectivity of the adsorbent for NO2 can avoid competitive adsorption of CO2.

[0241] The material for adsorption, capture and recovery of high-concentration nitrogen oxides in a post-processing plant in this embodiment is applied to adsorption, capture and recovery of high-concentration NOx in a post-processing plant.

[0242] The primary selection of NO2 adsorbent is mainly based on two principles:

[0243] 1) The main pore diameter of the adsorbent is larger than the NO2 kinetic diameter (~0.34nm);

[0244] 2) The adsorption space has a suitable size, which can promote the dimerization of NO2 in the pores to form N2O4 with a larger molecular volume, such as zeolites with more than ten-membered rings. The present invention selects MFI type ZSM-5 molecular sieve as the initial material and performs metal cation modification to obtain a material for the adsorption, capture and recovery of high-concentration NOx in post-treatment plants.

[0245] The material prepared in this embodiment for the adsorption, capture and recovery of high-concentration nitrogen oxides in post-processing plants can be applied to exhaust gases treated by the nuclear industry. The material in this embodiment has NO catalytic oxidation ability, hydrophobicity and can avoid competitive adsorption of CO2 on NO2, thereby improving treatment efficiency.

[0246] A high silicon-aluminum ratio can improve the hydrophobicity of the adsorbent, and a certain amount of Al ions can catalyze NO to NO2.

[0247] In order to avoid competitive adsorption of CO2, based on the -complexation interaction between transition metal ions and -bond (i.e., NO2) molecules, this embodiment developed a transition metal ion (nickel ion) exchange zeolite as a NO2 adsorbent. The high NO2 selectivity is related to the high interaction strength of π complexation, which is achieved by changing the type and valence of cations and the topological structure of the zeolite.

[0248] In addition, the role of metal cations (nickel ions) is to form supramolecular interactions with NO2 / N2O4 in a confined space, creating selective reversible adsorption of NO2 under the synergistic action of multi-site van der Waals forces, thereby promoting adsorbent regeneration and desorbed gas NO2 recovery.

[0249] In the adsorption process of this embodiment, the diffusion of nitrogen oxide molecules in the pores of the zeolite molecular sieve also plays an important role. The suitable pore structure thereof can promote the diffusion of nitrogen oxide molecules, making it easier for them to reach the adsorption sites and be adsorbed.

[0250] It will be understood that the above embodiments are merely exemplary embodiments for illustrating the principles of the present invention, and the present invention is not limited thereto. Those skilled in the art will appreciate that various modifications and improvements can be made without departing from the spirit and substance of the present invention, and such modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A material for the adsorption, capture and recovery of high-concentration nitrogen oxides, characterized in that: It is a nickel ion modified high silicon to aluminum ratio ZSM-5 zeolite molecular sieve.

2. The material for adsorption, capture and recovery of high-concentration nitrogen oxides according to claim 1, characterized in that: The high silicon to aluminum ratio of ZSM-5 zeolite molecular sieve is 200-500.

3. The material for adsorption, capture and recovery of high-concentration nitrogen oxides according to claim 1, characterized in that: ZSM-5 zeolite molecular sieve is represented by xNaOH·yC4H 16 N2·(z / 300)NaAlO2·zSiO2·wH2O, wherein x is 3-4; y is 2-3; z is 5-8; and w is 10-12.

4. A method for preparing a material for adsorption, capture and recovery of high-concentration nitrogen oxides according to any one of claims 1 to 3, characterized in that: The following steps are involved: The ZSM-5 zeolite molecular sieve with a high silicon-aluminum ratio is modified with a nickel ion solution to obtain a material for the adsorption, capture and recovery of high-concentration nitrogen oxides.

5. The method for preparing a material for adsorption, capture and recovery of high-concentration nitrogen oxides according to claim 4, characterized in that: The following steps are also included: Preparation of ZSM-5 zeolite molecular sieve with high silicon-aluminum ratio.

6. The method for preparing a material for adsorption, capture and recovery of high-concentration nitrogen oxides according to claim 5, characterized in that: The step of preparing the ZSM-5 zeolite molecular sieve with a high silicon-aluminum ratio specifically comprises the following steps: (1) Preparation of materials: silica sol, sodium aluminate, sodium hydroxide, 1,6-hexanediamine, and anhydrous ethanol; (2) mixing the raw materials in step (1) to obtain a mixed solution; (3) subjecting the obtained mixed solution to crystallization treatment; (4) After crystallization, the mixture is cooled, washed, and dried to obtain a ZSM-5 zeolite molecular sieve with a high silicon-aluminum ratio.

7. The method for preparing a material for adsorption, capture and recovery of high-concentration nitrogen oxides according to claim 6, characterized in that: The molar ratio of silica sol, sodium aluminate, sodium hydroxide and 1,6-hexanediamine in step (1) is x:y:(z / 300):z, wherein x is 3-4; y is 2-3; and z is 5-8.

8. The method for preparing a material for adsorption, capture and recovery of high-concentration nitrogen oxides according to claim 6, characterized in that: The mixing time of step (2) is 20 to 40 minutes, and the mixing is carried out by stirring at a stirring speed of 1000 to 1400 r / min.

9. The method for preparing a material for adsorption, capture and recovery of high-concentration nitrogen oxides according to claim 6, characterized in that: In the step (3), the crystallization treatment temperature is 165-168° C., and the crystallization treatment time is 3-4 days.

10. The method for preparing a material for adsorption, capture and recovery of high-concentration nitrogen oxides according to claim 6, characterized in that: The washing in step (4) is: repeatedly rinsing with water for 10 to 30 minutes.

11. The method for preparing a material for adsorption, capture and recovery of high-concentration nitrogen oxides according to claim 6, characterized in that: The drying in step (4) is specifically: drying at a temperature of 102-105° C. for 2-3 hours.

12. The method for preparing a material for adsorption, capture and recovery of high-concentration nitrogen oxides according to claim 4, characterized in that: The specific method for nickel ion modification of ZSM-5 zeolite molecular sieve with a high silicon-aluminum ratio comprises the following steps: Prepare nickel ion treatment solution; The ZSM-5 zeolite molecular sieve with a high silicon-aluminum ratio is mixed with a nickel ion treatment solution, and then subjected to vacuum impregnation treatment, and then filtered, dried, and calcined to obtain a modified ZSM-5 zeolite molecular sieve with a high silicon-aluminum ratio.

13. The method for preparing a material for adsorption, capture and recovery of high-concentration nitrogen oxides according to claim 12, characterized in that: The concentration of nickel ions in the prepared nickel ion treatment solution is 1-1.5 mol / L.

14. The method for preparing a material for adsorption, capture and recovery of high-concentration nitrogen oxides according to claim 12, characterized in that: The temperature of the vacuum impregnation treatment is 70-80° C., the time is 10-12 hours, and the vacuum degree is 0.1-0.3 Pa.

15. The method for preparing a material for adsorption, capture and recovery of high-concentration nitrogen oxides according to claim 12, characterized in that: The drying temperature after the vacuum impregnation treatment is 110 to 115° C., and the drying time is 1 to 3 hours.

16. The method for preparing a material for adsorption, capture and recovery of high-concentration nitrogen oxides according to claim 12, characterized in that: The calcination temperature after the vacuum impregnation treatment is 620-630° C., the time is 4-6 hours, and the calcination atmosphere is air atmosphere.

17. The method for preparing a material for adsorption, capture and recovery of high-concentration nitrogen oxides according to claim 12, characterized in that: The nickel ion content in the modified high silicon-aluminum ratio ZSM-5 zeolite molecular sieve is 1.8-2.1 mmol / g.

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