CN114307976B - Adsorbent and application thereof in separation of carbon dioxide/acetylene mixed gas - Google Patents
Adsorbent and application thereof in separation of carbon dioxide/acetylene mixed gas Download PDFInfo
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Abstract
The invention relates to the technical field of gas separation, in particular to carbon dioxide/acetylene mixed gas separation, and specifically relates to application of an adsorbent in carbon dioxide/acetylene mixed gas separation. The invention aims to solve the problems of high energy consumption and complex separation process of the existing carbon dioxide/acetylene mixed gas separation, and provides an adsorbent and application thereof in the carbon dioxide/acetylene mixed gas separation. The adsorbent prepared by the method has high structural stability, long cycle service life and simple separation process, can be separated by one step to obtain high-purity acetylene product gas compared with the traditional adsorbent, and effectively reduces the energy consumption of gas separation.
Description
Technical Field
The invention relates to the technical field of gas separation, in particular to separation of carbon dioxide/acetylene mixed gas, and specifically relates to an adsorbent and application thereof in separation of carbon dioxide/acetylene mixed gas.
Background
Acetylene is an important petrochemical basic raw material, is widely used for synthesizing organic products such as butanediol, acrylic acid, vinyl chloride and the like, and is also widely used in the gas welding and cutting industries. Carbon dioxide impurity gas is inevitably introduced in the current acetylene production process, so that the reduction of the purity of acetylene seriously influences the downstream application of the acetylene, and therefore, the carbon dioxide/acetylene mixed gas needs to be separated.
Carbon dioxide/acetylene separation is difficult due to the similar kinetic diameters, molecular sizes and boiling points. The traditional carbon dioxide/acetylene separation technology such as low-temperature rectification and solvent extraction technology has high separation energy consumption, is easy to corrode equipment and easily causes environmental pollution, and the adsorption separation technology can effectively reduce the separation energy consumption and has extremely important application value and prospect. However, most of the conventional adsorbents preferentially adsorb acetylene, and then acetylene is desorbed from the adsorbents to obtain high-purity acetylene product gas, if a carbon dioxide selective adsorbent can be used, the separation process can be greatly simplified, and the high-efficiency separation of carbon dioxide/acetylene can be realized through one-step separation to obtain high-purity acetylene gas, so that the characteristics of the adsorption separation technology are better met.
The Metal Organic Framework (MOF) has the advantages of rich structure, designable pore channel, easy functional modification and the like, and is suitable for constructing the high-efficiency adsorbent to solve the separation problem. The conventional unsaturated metal site is introduced to improve the adsorption affinity and further improve the adsorption selectivity, the regeneration energy consumption of the adsorbent is higher along with the increase of adsorption heat, and meanwhile, the structure stability of the adsorbent in a humid environment is poor. Molecular size sieving is a relatively ideal separation effect, however, for carbon dioxide/acetylene mixed gas with very close molecular size, precise regulation of the structural pore size is often very challenging, and the narrow pore size often limits the difference of gas adsorption capacity and adsorption diffusion rate, thereby affecting the actual separation effect. Considering that the influence factors of the actual separation effect of the mixed gas mainly comprise thermodynamic adsorption and kinetic factors, if the two separation mechanisms are combined for improvement, the synergistic effect of the two can also achieve a good separation effect even if the unilateral performance is not optimal.
Disclosure of Invention
The invention provides an adsorbent and application thereof in separation of carbon dioxide/acetylene gas mixture, aiming at solving the problems of high energy consumption and complex separation process of the existing carbon dioxide/acetylene gas mixture.
The invention is realized by adopting the following technical scheme: an adsorbent is obtained by the following preparation method: 1) adding yttrium nitrate hexahydrate, 3,3',5,5' -biphenyl tetracarboxylic acid and 2-fluorobenzoic acid into the mixtureN,NMixing and stirring the solution of dimethylformamide and water to dissolve the mixture to form a mixed solution, wherein yttrium nitrate hexahydrate, 3,3',5,5' -biphenyltetracarboxylic acid, 2-fluorobenzoic acid,N,N-dimethylformamide and water in a molar ratio of 2:1:82:1.28: 2.2; 2) putting the mixed solution into an oven for reaction until white crystals are obtained; 3) using the obtained white crystalsN,N-washing with a dimethylformamide solvent, followed by natural drying, thereby obtaining an adsorbent. The adsorbent prepared by the preparation method has the advantages of simple synthesis method, expandable synthesis scale and stable structure, and is suitable for batch production.
The adsorbent prepared by the preparation method is applied to the separation of carbon dioxide/acetylene mixed gas, the carbon dioxide/acetylene mixed gas is contacted with the adsorbent, and the separation of the carbon dioxide/acetylene is realized by an adsorption method. Because the structure of the adsorbent is a cage-type skeleton structure connected by the size of the ultramicropore window, the adsorption rate of acetylene can be effectively limited by the ultramicropore window, and the influence on the adsorption rate of carbon dioxide is small; meanwhile, the existence of the cage-shaped structure effectively ensures the adsorption quantity of carbon dioxide, and OH-in the structure can also form strong hydrogen bond action with carbon dioxide. The adsorbent is used for selectively adsorbing the carbon dioxide, so that carbon dioxide impurity gas is preferentially adsorbed in the separation process of mixed gas, high-purity acetylene product gas can be directly obtained from the outlet of the device, an additional adsorption-desorption cyclic process is not needed, the energy consumption of gas separation is further reduced, and the gas adsorption separation process flow is simplified.
Further, the application of the adsorbent in the separation of carbon dioxide/acetylene mixed gas comprises the following separation steps:
1) activating the adsorbent;
2) filling the activated adsorbent into an adsorption column;
3) introducing the carbon dioxide/acetylene mixed gas into an adsorption column filled with an adsorbent for separation, and directly collecting the separated acetylene product gas at the outlet end of the adsorption column, wherein the outlet end of the adsorption column adopts a gas chromatograph provided with a thermal conductivity detector to detect whether the gas is acetylene gas, if the gas chromatograph detects that the gas is acetylene, the gas is collected, and if the gas chromatograph detects that the gas is mixed gas, a gas collection channel is closed. In the separation step, whether the gas is acetylene gas or not is detected by adopting a gas chromatograph equipped with a thermal conductivity detector at the outlet end of the adsorption column, so that high-purity acetylene product gas is obtained, and the method is simple and practical.
The beneficial effects produced by the invention are as follows: the adsorbent prepared by the invention has the advantages of simple synthesis method, high structural stability and long cycle service life; meanwhile, the adsorbent is applied to the separation of carbon dioxide/acetylene mixed gas, and the high-purity acetylene product gas can be obtained through one-step separation due to preferential adsorption of carbon dioxide, and a desorption process flow after adsorption is not needed, so that the gas separation process flow is simplified, and the energy consumption of gas separation is effectively reduced.
Drawings
FIG. 1 is a scanning electron micrograph of an adsorbent according to the present invention;
FIG. 2 is a carbon dioxide adsorption isotherm of the adsorbent at a temperature of 0 deg.C;
FIG. 3 is a graph of pore size distribution for the adsorbent corresponding to FIG. 2;
FIG. 4 is a single component gas adsorption isotherm of carbon dioxide and acetylene with an adsorbent at room temperature;
FIG. 5 is a graph of the kinetic adsorption of an adsorbent for carbon dioxide and acetylene at room temperature;
FIG. 6 is a graph showing the separation of an adsorbent at room temperature against a carbon dioxide/acetylene mixture gas of equal volume ratio;
FIG. 7 is a schematic diagram of a cyclic breakthrough test of an adsorbent on a carbon dioxide/acetylene gas mixture;
fig. 8 is a graph of the separation of adsorbent material 5A molecular sieve versus an equal volume ratio of carbon dioxide/acetylene mixed gas at room temperature.
Detailed Description
An adsorbent obtained by the following preparation method: 1) 38.3 mg of yttrium nitrate hexahydrate, 16.5 mg of 3,3',5,5' -biphenyltetracarboxylic acid and 1g of 2-fluorobenzoic acid were added to 5 mL of the mixtureN,N-dimethylformamide and 2mL of water are dissolved by stirring to form a mixed solution; 2) putting the mixed solution into an oven for reaction at the reaction temperature of 120 ℃ for 3 days to obtain white crystals; 3) the obtained white crystals were used in an amount of 10 mLN,N-dimethylformamide solvent washing three times, and then placing in air for natural drying, thereby obtaining the adsorbent, as shown in fig. 1, and as can be seen from fig. 1, the obtained adsorbent has a cubic morphology with smooth surface and no impurities. The adsorbent prepared by the preparation method has the advantages of simple synthesis method, expandable synthesis scale and stable structure, and is suitable for batch production.
Performance experiments of the adsorbents prepared by the above preparation methods:
experiment one: the adsorbent is used for testing the adsorption capacity of the single-component gas of carbon dioxide and acetylene at room temperature, as shown in figure 4 and can be seen from figure 4, the adsorption capacity of carbon dioxide is higher than that of acetylene, which shows that the material has stronger adsorption affinity for carbon dioxide and has the potential of separating carbon dioxide/acetylene mixtures;
experiment two: the dynamic adsorption curves of the adsorbent for carbon dioxide and acetylene at room temperature were tested, and as can be seen from fig. 5 and from fig. 5, the adsorption rate of carbon dioxide was significantly faster than that of acetylene, indicating that the adsorbent can achieve separation of carbon dioxide/acetylene mixtures by a kinetic effect.
The adsorbent prepared by the preparation method is applied to the separation of carbon dioxide/acetylene mixed gas, and the carbon dioxide/acetylene is separated by contacting the carbon dioxide/acetylene mixed gas with the adsorbent and utilizing an adsorption method. As shown in fig. 2 and fig. 3, it can be seen that the pore diameter of the adsorbent is about 0.4 nm, which indicates that the adsorbent material has an ultramicropore structure, and since the structure is a cage-type skeleton structure connected by the size of an ultramicropore window, the adsorption rate of acetylene can be effectively limited through the window, and the influence on the adsorption rate of carbon dioxide is small; meanwhile, the existence of the cage-shaped structure effectively ensures the adsorption quantity of carbon dioxide, and OH-in the structure can also form strong hydrogen bond action with carbon dioxide. The adsorbent is used for selectively adsorbing the carbon dioxide, so that carbon dioxide impurity gas is preferentially adsorbed in the separation process of the carbon dioxide/acetylene mixed gas, high-purity acetylene product gas can be directly obtained from an outlet of an adsorption column, the acetylene product gas can be obtained by further separation, an additional adsorption-desorption cyclic process is not needed, the gas separation energy consumption is further reduced, and the gas adsorption separation process flow is simplified.
Further, the application of the adsorbent prepared by the preparation method in the separation of carbon dioxide/acetylene mixed gas comprises the following separation steps:
1) activating the adsorbent under the condition of high vacuum degree, wherein the activation temperature is 300 ℃, and the activation time is 6 hours, so as to obtain the activated adsorbent;
2) loading the activated adsorbent into a stainless steel adsorption column with the diameter of 4 multiplied by 130mm, and purging for half an hour by using nitrogen;
3) introducing the carbon dioxide/acetylene mixed gas into an adsorption column filled with an adsorbent for separation, adjusting the inlet pressure of the carbon dioxide/acetylene mixed gas to be 1.01bar by an adjusting valve, adjusting the flow rate of the carbon dioxide/acetylene mixed gas to be 3.3mL/min by a gas mass flow meter, and adjusting the indoor temperature to be 25 ℃, and then directly collecting the separated acetylene product gas at the outlet end of the adsorption column, wherein the outlet end of the adsorption column adopts a gas chromatograph equipped with a thermal conductivity detector to detect whether the gas is acetylene gas, if the gas detected by the gas chromatograph is acetylene, collecting the gas, and if the gas detected by the gas chromatograph is mixed gas, closing a gas collecting channel, wherein the flow rate, the pressure and the temperature of the carbon dioxide/acetylene mixed gas are kept unchanged in the separation process. In the separation step, whether the gas is acetylene gas or not is detected by adopting a gas chromatograph equipped with a thermal conductivity detector at the outlet end of the adsorption column, so that high-purity acetylene product gas is obtained, and the method is simple and practical.
As shown in fig. 6, as can be seen from the separation curve of the adsorbent against carbon dioxide/acetylene mixed gas with equal volume ratio at room temperature, the adsorbent can preferentially adsorb carbon dioxide in the separation of carbon dioxide/acetylene mixed gas, and acetylene is detected at the outlet first through a short adsorption process, so that high-purity acetylene can be stably obtained for a long time. As shown in fig. 7, the adsorbent maintained substantial gas separation performance after 5 cycles breakthrough testing.
Comparative example: the activated molecular sieve 5A is put into a stainless steel adsorption column with the diameter of 4 multiplied by 130mm, a gas separation experiment is carried out at the room temperature of 25 ℃, the inlet pressure is 1.01bar, and the flow rate of acetylene/carbon dioxide mixed gas is 3.3mL/min, and as can be observed from a graph of figure 8, under the same separation condition of the adsorbent prepared by the invention, the separation effect of the adsorbent 5A molecular sieve on the acetylene/carbon dioxide mixed gas is poor, so that the co-adsorption time is long, the separation time is short, acetylene is preferentially adsorbed, high-purity acetylene product gas cannot be obtained through one-step separation, the subsequent separation step is increased, and the reduction of the energy consumption of gas separation is not facilitated.
Claims (9)
1. The application of the adsorbent in the separation of carbon dioxide/acetylene mixed gas is characterized in that the adsorbent is prepared by the following preparation method: 1) adding yttrium nitrate hexahydrate, 3,3',5,5' -biphenyl tetracarboxylic acid and 2-fluorobenzoic acid into the mixtureN,NMixing and stirring the solution of dimethylformamide and water to dissolve the dimethylformamide and the water to form a mixed solution, whereinYttrium nitrate hydrate, 3,3',5,5' -biphenyltetracarboxylic acid, 2-fluorobenzoic acid,N,N-dimethylformamide and water in a molar ratio of 2:1:82:1.28: 2.2; 2) putting the mixed solution into an oven for reaction until white crystals are obtained; 3) using the obtained white crystalsN,N-washing with a dimethylformamide solvent, followed by natural drying, thereby obtaining an adsorbent.
2. The use of the adsorbent in the separation of a carbon dioxide/acetylene mixed gas according to claim 1, wherein the mixed solution is placed in an oven to react at a reaction temperature of 120 ℃ for 3 days.
3. The use of an adsorbent according to claim 1 or 2 in the separation of a carbon dioxide/acetylene mixture, wherein the carbon dioxide/acetylene mixture is contacted with the adsorbent and the separation of carbon dioxide/acetylene is achieved by adsorption.
4. The use of an adsorbent according to claim 1 or 2 in the separation of a carbon dioxide/acetylene mixture, comprising the following separation steps:
1) activating the adsorbent;
2) filling the activated adsorbent into an adsorption column;
3) introducing the carbon dioxide/acetylene mixed gas into an adsorption column filled with an adsorbent for separation, and directly collecting the separated acetylene product gas at the outlet end of the adsorption column, wherein the outlet end of the adsorption column adopts a gas chromatograph provided with a thermal conductivity detector to detect whether the gas is acetylene gas, if the gas detected by the gas chromatograph is acetylene, the gas is collected, and if the gas detected by the gas chromatograph is mixed gas, a gas collection channel is closed.
5. The use of an adsorbent in the separation of a carbon dioxide/acetylene gas mixture according to claim 4, wherein the activation in step 1) is carried out under a high vacuum.
6. The use of an adsorbent in the separation of a carbon dioxide/acetylene gas mixture according to claim 5, wherein the activation temperature in step 1) is 300 ℃ and the activation time is 6 hours.
7. The use of an adsorbent according to claim 6 in the separation of a carbon dioxide/acetylene mixture, wherein the flow rate, pressure and temperature of the carbon dioxide/acetylene mixture are maintained during the separation.
8. The use of an adsorbent in the separation of a carbon dioxide/acetylene gas mixture according to claim 7, wherein the inlet pressure of the carbon dioxide/acetylene gas mixture is adjusted to 1.01bar by a regulating valve, the flow rate of the carbon dioxide/acetylene gas mixture is adjusted to 3.3mL/min by a gas mass flow meter, and the indoor temperature is 25 ℃.
9. The use of an adsorbent according to claim 8 in the separation of a carbon dioxide/acetylene gas mixture, wherein the adsorption column is a 4 x 130mm stainless steel column.
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| DE102005054523A1 (en) * | 2005-11-14 | 2007-05-16 | Basf Ag | Porous organometallic framework containing another polymer |
| CN103657607B (en) * | 2013-11-20 | 2015-08-19 | 中北大学 | A kind of metal ion surface carbonization graft type polymeric adsorbent and preparation method thereof |
| WO2017210874A1 (en) * | 2016-06-08 | 2017-12-14 | Xia, Ling | Imperfect mofs (imofs) material, preparation and use in catalysis, sorption and separation |
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| CN106459590A (en) * | 2014-03-27 | 2017-02-22 | 巴斯夫欧洲公司 | Porous films comprising metal-organic framework materials |
| CN105237565A (en) * | 2015-11-19 | 2016-01-13 | 辽宁大学 | Metal organic framework material based on lead nitrate and application thereof |
| CN105312029A (en) * | 2015-12-02 | 2016-02-10 | 福建师范大学 | MOFs material capable of effectively separating acetylene mixed gas and preparation method of MOFs material |
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