An adsorption resin for separating hydrogen and nitrogen and its preparation method

Abstract

The present invention discloses an adsorbent resin for separating hydrogen and nitrogen and a preparation method thereof. By carrying out special functional modification on a hydrophobic styrene resin, an adsorbent is designed which contains hierarchical pores and is beneficial to the mass transfer and diffusion of gas adsorbate molecules inside the adsorbent. Finally, the adsorbent has good separation ability for H2 and N2 and is easy to regenerate, expanding the application of the adsorbent resin in the separation and purification of special gases, and solving the problems that the 5A molecular sieve used for separating H2 and N2 in the prior art is sensitive to water vapor, has a high activation temperature, and has narrow pores which are not conducive to mass transfer and diffusion.

Description

Technical field:

[0001] The invention relates to the technical field of adsorption resins for separation of hydrogen and nitrogen, and in particular to an adsorption resin for separation of hydrogen and nitrogen and a preparation method thereof. Background technology:

[0002] Hydrogen is an important industrial raw material and also the cleanest energy source. The preparation, separation and application of hydrogen are hot topics in today's society. There are many hydrogen production processes, such as coal-to-hydrogen, methanol-to-hydrogen, water electrolysis and biomass conversion. Among them, water electrolysis accounts for only 1% of hydrogen production. Most of the hydrogen is obtained by separation and purification from mixed gases containing hydrogen. 2 and N 2 Separation is mainly carried out through membrane separation and pressure swing adsorption separation. However, the purity of hydrogen obtained by membrane separation is generally lower than 99%, which is difficult to meet application requirements. The pressure swing adsorption process can not only obtain hydrogen with a purity higher than 99.9%, but also has the convenience of easy scalability. The raw mixed gas containing different proportions of hydrogen has a wide range of sources, such as water gas, methanol production purge gas, and ammonia production purge gas. Producing hydrogen from non-renewable resources does not meet the requirements of the sustainable development route. Hydrogen production through biomass conversion has great prospects. Renewable resources such as biomass, such as wood and straw, are inexhaustible, and my country is a major agricultural country. Generally, hydrogen-rich synthesis gas is obtained by high-temperature carbonization of biomass, and it also contains H 2 、N 2 , CO, CH 4 and CO 2 . H in the pressure swing adsorption process 2 With N 2 The separation of residual N 2 It will affect the purity of hydrogen, thus limiting the application of hydrogen in high-tech fields. At present, in the common industrial pressure swing adsorption process, 5A molecular sieve is generally used to separate H 2 and N 2 However, 5A molecular sieve is sensitive to water vapor and is easily deactivated. In addition, the activation temperature is too high during regeneration, which poses a great safety hazard. In addition, the pores of 5A molecular sieve are uniform and narrow, and the gas molecule mass transfer is slow, resulting in H 2 and N 2 Separation requires a relatively high fixed adsorption bed, generally 5 m, and needs to be carried out under high pressure. This places extremely high demands on the safety performance of the equipment. 2 and N 2 To improve the performance, it is necessary to introduce Li+ into the molecular sieve framework through multiple ion exchanges, which increases the preparation cost of the adsorbent. 2 The molecular binding force is strong, and there will still be more N after desorption at reduced pressure 2Residue affects the regeneration performance of the adsorbent.

[0003] Styrene-based macroporous adsorption resins, with high specific surface area and hierarchical pores, and good mechanical strength and spherical morphology, have been widely used in industrial wastewater treatment, heavy metal ion enrichment, and air VOCs removal. The resin is rich in phenyl structures and is easily chemically modified, which enables the adsorption resin to be easily designed and modified according to the adsorption separation target to achieve selective adsorption. Although macroporous adsorption resins have good application value in the field of water body adsorption, they are rarely used in gas separation and purification. Summary of the Invention:

[0004] The object of the present invention is to provide an adsorption resin for hydrogen and nitrogen separation and its preparation method. The hydrophobic styrene resin is specially functionally modified to design a resin containing hierarchical pores that is beneficial to the mass transfer and diffusion of gas adsorbate molecules inside the adsorbent. Finally, it has good separation ability for H 2 and N 2 and an adsorbent that is easy to regenerate, expanding the application of adsorption resins in the separation and purification of special gases, and solving the problems that the existing technology for separating H 2 and N 2 using 5A molecular sieve is sensitive to water vapor, has a high activation temperature, and the narrow pores are not conducive to mass transfer and diffusion.

[0005] The present invention is realized through the following technical solutions:

[0006] An adsorption resin for hydrogen and nitrogen separation, whose backbone structure is polystyrene divinylbenzene. An organic amine structure is introduced into the backbone of the styrene-based resin, and through protonation, the interaction force between the resin and N 2 molecules is enhanced. The fixed bed of this resin can effectively separate H 2 and N 2 , and the fixed bed can be regenerated by vacuum desorption.

[0007] The preparation method of the adsorption resin for hydrogen and nitrogen separation includes the following steps:

[0008] 1) Swell the chlorine beads in an organic solvent at 25 - 45 °C for 6 - 12 h; the chlorine beads are styrene-divinylbenzene backbone resins, and the mass ratio of the chlorine beads to the organic solvent is 1:5 - 1:10; the organic solvent is one or a mixture of nitrobenzene, dichloroethane, and chlorobenzene;

[0009] 2) According to the chloromethyl content, add a catalyst, and then stir the system evenly at room temperature. Then raise the temperature of the system to 60 - 80 °C, control the reaction time to be 0.5 - 2 h. After the reaction ends, cool the system to room temperature, filter out the resin, wash it with ethanol and dilute acid multiple times, then wash it with pure water until the filtrate is neutral, and then wash it with ethanol multiple times, and dry it at 100 °C; the dosage of the catalyst is m(catalyst):m(chlorinated beads) = 0.1 - 0.3, and the catalyst is AlCl 3 、FeCl 3 and ZnCl 2 or a mixture of one or more of them;

[0010] 3) Take the resin obtained in step 2) and swell it in an organic solvent for a certain time. Add an organic amine and a base catalyst to the system, stir for 2 h at a certain temperature, then raise the temperature of the system to 60 - 100 °C and react for 4 - 8 h. Filter while it is hot, wash it with hot water multiple times, then soak it in a dilute acid solution for a period of time, then wash it with water until it is neutral, and finally wash it with ethanol multiple times and dry it.

[0011] The dilute acid used in step 2) is one of HCl and H 2 SO 4 , and the concentration of the dilute acid is controlled at 0.1 - 1 mol / L. The drying method is vacuum drying or air-blowing drying.

[0012] The organic solvent in step 3) is one or a mixture of N,N-dimethylformamide or dimethyl sulfoxide. When it is a mixed solvent, the two are mixed in any proportion.

[0013] The organic amine used in step 3) is one or a mixture of organic amines such as triethylenetetramine, tetraethylenepentamine, polyethyleneimine with different molecular weights, and melamine. The dosage of the organic amine is m(organic amine):m(resin) = 0.2 - 0.6. The base catalyst used is K 2 CO 3 or Na 2 CO 3 or a mixture of one or more of them, and the dosage of the base catalyst is n(catalyst):n(organic amine) = 3:1 - 1:1.

[0014] The dilute acid used in step 3) is one or a mixture of HCl, HBr, HI, HBF 4 and H 2 SO 4 , and the concentration of the dilute acid is 0.1 - 1 mol / L.

[0015] The present invention also protects the application of the adsorption resin for separating hydrogen and nitrogen. Fill the resin into a column, and at a pressure of 100 KPa and a temperature of 25 °C, pass a hydrogen and nitrogen mixed gas through the adsorption column at room temperature.

[0016] At room temperature, a vacuum pump is used to reduce the pressure of the adsorption column for desorption to achieve regeneration.

[0017] The beneficial effects of the present invention are as follows: The organic amine cation is introduced into the polystyrene divinylbenzene adsorption resin framework, enhancing the interaction force between the resin and N 2 molecules, improving the adsorption capacity of the macroporous adsorption resin for N 2 and the separation capacity of N 2 / H 2 Moreover, the binding force between the organic amine cation and N 2 is weaker than the binding force between Li+ and N 2 , making it easier for the resin to recover and regenerate by pressure reduction desorption. The resin contains macropores and mesopores, which are beneficial for gas molecules to quickly diffuse inside the pores, increasing the utilization efficiency of adsorption sites and reducing the pressure for separating H 2 and N 2 by the pressure swing adsorption process. In addition, the resin has a controllable and uniform particle size, which is very suitable as an adsorbent in the adsorption column, and thus has good application prospects. Brief Description of the Drawings:

[0018] Figure 1 is the breakthrough curve of H 2 and N 2 of 5A molecular sieve and the adsorption resin prepared in Example 2 at 298K;

[0019] Among them, at 298K, the time difference for H 2 and N 2 to break through the 5A molecular sieve is 3 min, while the time difference for H 2 and N 2 to break through the organic amine cationized resin adsorption column is 3.5 min. It can be seen that the organic amine cationized resin has good H 2 and N 2 separation ability. Detailed Embodiments:

[0020] The following is a further description of the present invention, rather than a limitation of the present invention.

[0021] Example 1:

[0022] Take 30 g of chlorinated beads and swell them in 100 mL of dichloroethane at room temperature for 12 h. Add 6 g of AlCl 3 , and stir at room temperature for 2 h. Heat the system to 80 °C and stir for reaction for 1 h. After the system cools, filter out the resin. Then wash it with ethanol multiple times, then wash it with 0.1 mol / L HCl three times, then wash it with water until neutral, and then wash it with ethanol twice, and dry it at 100 °C.

[0023] Take 10 g of the post-crosslinked resin prepared above and swell it in 100 mL of DMF at room temperature for 12 h. Add 5.8 g of tetraethylenepentamine and 13.34 g of K 2 CO 3 . Heat to 80 °C and react for 8 h. Filter while it is hot, wash with hot water multiple times, soak the resin in 0.1 mol / L HBF 4 for 12 h. Wash with pure water until the filtrate is neutral, then wash with ethanol multiple times, and dry in a forced-air drying oven for 12 h.

[0024] Example 2:

[0025] Take 30 g of chlorinated beads and swell them in 100 mL of nitrobenzene at room temperature for 12 h. Add 6 g of AlCl 3 , and stir at room temperature for 2 h. Heat the system to 80 °C and stir and react for 0.5 h. After the system cools, filter out the resin. Then rinse with ethanol multiple times, then wash with 0.1 mol / L HCl three times, then wash with water until neutral, then wash with ethanol twice, and dry at 100 °C.

[0026] Take 10 g of the post-crosslinked resin prepared above and swell it in 100 mL of DMF at room temperature for 12 h. Add 5.8 g of polyethyleneimine and 13.34 g of Na 2 CO 3 . Heat to 80 °C and react for 8 h. Filter while it is hot, wash with hot water multiple times, soak the resin in 0.1 mol / L HBr for 12 h. Wash with pure water until the filtrate is neutral, then wash with ethanol multiple times, and dry in a forced-air drying oven for 12 h.

[0027] Example 3:

[0028] Take 30 g of chlorinated beads and swell them in 100 mL of dichloroethane at room temperature for 12 h. Add 6 g of AlCl 3 , and stir at room temperature for 2 h. Heat the system to 80 °C, stir and react for 0.5 h. After the system cools, filter out the resin. Then rinse with ethanol multiple times, then wash with 0.1 mol / L HCl three times, then wash with water until neutral, then wash with ethanol twice, and dry at 100 °C.

[0029] Take 10 g of the post-crosslinked resin prepared above and swell it in 100 mL of DMSO at room temperature for 12 h. Add 5.8 g of melamine and 13.34 g of K 2 CO 3 . Heat to 80 °C and react for 8 h. Filter while it is hot, wash with hot water multiple times, soak the resin in 0.1 mol / L HCl for 12 h. Wash with pure water until the filtrate is neutral, then wash with ethanol multiple times, and dry in a forced-air drying oven for 12 h.

[0030] Example 4:

[0031] The H of the resin was investigated by dynamic adsorption method 2 and N 2 separation performance: A certain dry volume of the resin prepared in Example 2 or 5A molecular sieve was filled into a column of 10 cm × 1.8 cm. At a column head pressure of 100 KPa and a temperature of 25 °C, the mixed gas (V(H 2 ):V(N 2 ) = 90:10) was passed through the adsorption column at a flow rate of 10 mL / min at room temperature, and the tail gas components were detected by gas chromatography. The results are shown in Table 1 or Table 2.

[0032] Figure 1 is the breakthrough curve of H 2 and N 2 of 5A molecular sieve and the adsorption resin prepared in Example 2 at 298 K;

[0033] Among them, at 298 K, the time difference for H 2 and N 2 to break through 5A molecular sieve is 3 min, while the time difference for H 2 and N 2 to break through the organic amine cationized resin adsorption column is 3.5 min. It can be seen that the organic amine cationized resin has good H 2 and N 2 separation ability.

[0034] At room temperature, the adsorption column was depressurized and desorbed by a vacuum pump to achieve regeneration.

[0035] Table 1 Tail gas components of 5A molecular sieve adsorption column

[0036]

[0037]

[0038] Table 2 Tail gas components of cationized resin adsorption column

[0039] Time (min) <![CDATA[H 2 Peak area]]> <![CDATA[H 2 Percentage content (%)]]> <![CDATA[N 2 Peak area]]> <![CDATA[N 2 Percentage content (%)]]> 1 0 0 0 0 2 0 0 0 0 3 0 0 0 0 4 0 0 0 0 5 0 0 0 0 5.5 17355 0.11 0 0 6 189333 1.21 0 0 6.5 1183333 7.35 0 0 7 2447133 15.51 0 0 7.5 3108222 19.72 0 0 8 4307333 27.23 0 0 8.5 5063018 32.09 0 0 9 6452511 41.53 9670 0.51 10 8214089 53.61 29123 1.14 11 10903573 66.65 90662 4.55 12 11421610 76.09 131107 6.59 13 13393575 83.56 156917 8.06 14 13984544 88.45 178719 9.15 15 14340217 90.09 192505 9.91

Claims

1. Application of an adsorbent resin for hydrogen and nitrogen separation, Characterized in that, The resin is loaded into a column, and a mixed gas of hydrogen and nitrogen is passed through the adsorption column at room temperature under a pressure of 100 KPa and a temperature of 25 °C; the resin has a polystyrene divinylbenzene backbone structure, an organic amine structure is introduced into the backbone of the styrene-based resin, and through protonation, the fixed bed of this resin can effectively separate H 2 and N 2 , and the fixed bed is regenerated by pressure reduction desorption; the preparation method of the adsorption resin comprises the following steps: 1) Swell the chlorinated beads in an organic solvent at 25 - 45 °C for 6 - 12 h; the chlorinated beads are styrene - divinylbenzene framework resins, and the mass ratio of the chlorinated beads to the organic solvent is 1:5 - 1:10; the organic solvent is one or a mixture of nitrobenzene, dichloroethane, and chlorobenzene; 2) According to the chloromethyl content, add a catalyst, then stir the system evenly at room temperature, then heat the system to 60 - 80 °C, control the reaction time to be 0.5 - 2 h. After the reaction ends, cool the system to room temperature, filter out the resin, wash it repeatedly with ethanol and dilute acid, then wash it with pure water until the filtrate is neutral, and then wash it repeatedly with ethanol, and dry it at 100 °C; the mass dosage of the catalyst is m(catalyst):m(chlorinated beads)=0.1 - 0.3, and the catalyst is AlCl 3 , FeCl 3 and ZnCl 2 or a mixture of several of them; 3) Take the resin obtained in step 2), swell it in an organic solvent for a certain time, add an organic amine and a base catalyst to the system, stir at a certain temperature for 2 h, raise the temperature of the system to 60 - 100 °C, and react for 4 - 8 h. Filter while it is hot, wash it with hot water multiple times, then soak it in a dilute acid solution for a period of time, then wash it with water until neutral, and finally wash it with ethanol multiple times and dry it.

2. The application of the adsorbent resin for hydrogen and nitrogen separation according to claim 1, Characterized in that, At room temperature, use a vacuum pump to depressurize and desorb the adsorption column to achieve regeneration.

3. The application of the adsorbent resin for hydrogen and nitrogen separation according to claim 1, Characterized in that, Step 2) The dilute acid used is one of HCl and H 2 SO 4 , and the concentration of the dilute acid is controlled at 0.1 - 1 mol / L.

4. The application of the adsorbent resin for hydrogen and nitrogen separation according to claim 1, Characterized in that, The drying method in step 2) is vacuum drying or air - blast drying.

5. The application of the adsorbent resin for hydrogen and nitrogen separation according to claim 1, Characterized in that, The organic solvent in step 3) is one or a mixture of N,N - dimethylformamide or dimethyl sulfoxide. When it is a mixed solvent, the two are mixed in any proportion.

6. The application of the adsorbent resin for hydrogen and nitrogen separation according to claim 1, Characterized in that, The organic amine used in step 3) is one or a mixture of triethylenetetramine, tetraethylenepentamine, polyethyleneimines with different molecular weights, and melamine. The mass dosage of the organic amine is m(organic amine):m(resin)=0.2 - 0.

6.

7. The application of the adsorbent resin for hydrogen and nitrogen separation according to claim 1, Characterized in that, The base catalyst used in step 3) is K 2 CO 3 or Na 2 CO 3 or a mixture thereof, and the mass ratio of the base catalyst to the organic amine is n(catalyst):n(organic amine) = 3:1 to 1:

1.

8. The application of the adsorbent resin for hydrogen and nitrogen separation according to claim 1, Characterized in that, The dilute acid used in step 3) is one or a mixture of several of HCl, HBr, HI, HBF 4 and H 2 SO 4 , and the concentration of the dilute acid is 0.1 - 1 mol / L.

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