Device and method for efficiently capturing C4 aldol isomer volatile organic compound by using ionic liquid

Abstract

The invention relates to a device and a method for efficiently capturing C4 aldol isomer volatile organic compounds by using ionic liquid. The efficient capturing of four VOCs (Volatile Organic Compounds) NBA, NBU, IBA and IBU is realized by using an ionic liquid absorbent [BMIM] [TFO]. Specifically, a COSMO-SAC model is used for screening ionic liquid absorbents, [BMIM] [TFO] and [EMIM] [TFO] which have advantages in the aspects of solubility, selectivity and cost are preliminarily selected as the absorbents, and then absorption experiments and quantum chemistry analysis prove that the two ionic liquid absorbents can achieve the effect that the mass fraction of four VOCs is smaller than 0.02% after absorption, and the two ionic liquid absorbents can achieve the effect that the mass fraction of the four VOCs is smaller than 0.02% after absorption. The purity of the circulated ILs absorbent is greater than 99.9%. Compared with a [EMIM] [TFO] absorption system, the [BMIM] [TF0] absorption system has the advantages that the solvent consumption can be reduced by 26.26%, the alcohol aldehyde trapping effect is better, and the application range of the ionic liquid in fine chemical waste gas treatment is expanded.

Description

Technical Field

[0001] The present invention belongs to the field of fine chemical separation and purification, and particularly relates to a method for capturing C4 alcohol aldehyde isomer volatile organic compounds by using ionic liquids.

Background Art

[0002] As an important source of air pollution, volatile organic compounds (VOCs) have attracted much attention due to their potential environmental risks and health threats. In recent years, against the background of the rapid development of industries such as chemical engineering, pharmaceuticals, and coatings, the emissions of VOCs have been continuously increasing. Alcohol aldehyde compounds such as n-butanol (NBA), n-butanal (NBU), isobutanol (IBA), and isobutyraldehyde (IBU) have been listed as key research objects due to their wide applications in the industrial field. However, their volatile gases not only affect industrial production safety but also pose significant hazards to the ecological environment and the human respiratory system.

[0003] In response to the need for VOCs pollution control, ionic liquids (ILs) have become a promising new type of absorbent material due to their strong designability and low vapor pressure. Research shows that ILs exhibit excellent selective absorption capabilities for VOCs components such as fluorine-containing gases, chlorobenzene, benzene series, and sulfides, and their adsorption efficiency for polar molecules such as methanol and hydrogen sulfide is particularly prominent. This characteristic provides an important material basis for the development of efficient VOCs recovery technologies.

[0004] Patent (CN221999376U) discloses an integrated multi-stage VOCs absorption device, which treats harmful gases through the synergistic action of a spray tower, a dry filter, and a transfer component. However, this device has a complex structure and is difficult to operate.

[0005] Patent (CN117717878A) discloses a method for efficiently absorbing toluene waste gas at atmospheric pressure using ionic liquids. This method uses an ionic liquid absorbent, passes through a toluene absorption tower to separate toluene in the waste gas and dissolve it in the ionic liquid, and then undergoes atmospheric pressure stripping and purification to reduce the toluene content. However, this process is complex and does not adopt a heat integration process, resulting in high energy consumption.

[0006] The present invention realizes the efficient capture of four VOCs, namely NBA, NBU, IBA, and IBU, by using the ionic liquid absorbent [BMIM][TFO]. Specifically, the present invention uses the COSMO-SAC model to screen ionic liquid absorbents, and initially selects [BMIM][TFO] and [EMIM][TFO] which have advantages in solubility, selectivity, and cost as absorbents. Subsequently, absorption experiments and quantum chemical analyses have proven that for both ionic liquid absorbents, the mass fraction of the four VOCs after absorption is less than 0.02%, and the purity of the recycled ILs absorbent is greater than 99.9%. Compared with the [EMIM][TFO] absorption system, the use of the [BMIM][TF0] absorption system can reduce the solvent usage by 26.26%, and has a better capture effect on aldehydes and alcohols, expanding the application scope of ionic liquids in the treatment of fine chemical waste gas.

Summary of the Invention

[0007] [Technical Problem to be Solved]

[0008] The object of the present invention is to provide a method for efficiently capturing four VOCs by using ionic liquids. This method has a better capture effect on aldehydes and alcohols, and can also reduce the cost of the process.

[0009] Another object of the present invention is to provide the method and device to improve the separation efficiency of NBA, NBU, IBA, and IBU waste gas and avoid waste of absorbent.

[0010] [Technical Solution]

[0011] The present invention is realized by the following technical solutions.

[0012] Provide a method for efficiently capturing four VOCs, namely NBA, NBU, IBA, and IBU. The device for capturing NBA, NBU, IBA, and IBU mainly includes the following parts: absorption tower (T1), separator (T2), centrifugal pump 1 (P1), centrifugal pump (P2), heater (H1), condenser (C1), heat exchanger (H2); N2 is separated from the top of the absorption tower (T1), and the bottom mixed fluid flows through centrifugal pump 1 (P1) and heater (H1) and enters the separator (T2); waste heat recovery is carried out on the ILs stream after high-temperature and low-pressure desorption, and it is heat-exchanged with the VOCs-rich stream entering the separator (T2). The required VOCs are separated from the top of the separator (T2), and the bottom absorbent is condensed by the condenser (C1) and returns to the absorption tower (T1) via a pipeline together with the supplemented fresh absorbent.

[0013] The method for efficiently capturing four VOCs, namely NBA, NBU, IBA, and IBU, invented mainly includes the following steps:

[0014] (1) NBA, NBU, IBA, IBU and N2 are introduced from the bottom of an absorption tower (T1), and an absorbent is introduced from the top of the absorption tower (T1) to contact with the gas in a countercurrent manner. N2 is separated from the top of the absorption tower (T1), and the absorbent and NBA, NBU, IBA, IBU enter a separator (T2) from the bottom of the absorption tower (T2) via a centrifugal pump 1 (P1) and a heater (H2).

[0015] (2) In the separator (T2), NBA, NBU, IBA, and IBU are separated from the upper part of the separator (T2), and the waste heat of the ILs stream after high-temperature and low-pressure desorption is recovered and heat exchanged with the VOCs-rich stream entering the separator (T2). Part of the absorbent is cooled by the condenser (C1) and then refluxed to the separator (T2), and part of it is returned to the absorption tower (T1) together with the supplementary absorbent through the heat exchanger (H2).

[0016] Provided is a device for efficiently capturing four VOCs, NBA, NBU, IBA and IBU, using ionic liquids, including an ILs storage tank, a water supply pump, an absorption tower, an ILs storage tank containing VOCs, a gas chromatograph, a VOCs generator and a VOCs storage tank; further described: high-purity N2 (99.999%) is precisely pressure-regulated by a pressure reducing valve, and then flow-calibrated by a mass flow controller, and then introduced into a generator containing a VOCs mixed solvent in an equal molar ratio. The simulated exhaust gas carrying VOCs is introduced into the absorption tower through a distributed gas distribution system at the bottom of the tower. The absorbent is injected from the top of the tower at a specified flow rate through a constant-flow peristaltic pump to form a gas-liquid reverse micro-contact mass transfer process, and the system is maintained at (298.15±0.1)K through a precise temperature control system. The tail gas detection adopts an online gas chromatography analysis scheme: the periodically sampled gas phase components are introduced into the GC-2014C system through a six-way valve. Data acquisition and peak area integration are realized through a LabSolutions workstation, and the concentration of residual VOCs in the gas phase is quantitatively analyzed based on the external standard method. Three parallel determinations were performed for each experiment, and the relative standard deviation was controlled within 2%.

[0017] According to another preferred embodiment of the present invention, the method for absorbing a mixture of four VOCs, NBA, NBU, IBA and IBU, by using ionic liquid is characterized in that: [EMIM][TFO] ionic liquid is used to absorb NBA, NBU, IBA and IBU, the mass fraction of the four VOCs is less than 0.02%, and the purity of the circulating ILs is greater than 99.9%.

[0018] [Beneficial Effects]

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] (1) The present invention achieves efficient capture of four VOCs: NBA, NBU, IBA and IBU.

[0021] (2) The present invention uses ionic liquid as an absorbent to absorb four VOCs, namely NBA, NBU, IBA and IBU, reducing the harm to the environment.

[0022] (3) The process of the present invention is simple and easy to operate, successfully separating four VOCs, namely NBA, NBU, IBA and IBU, and reducing the cost of the process.

Description of the Drawings

[0023] Figure 1 It is a process flow chart of a method for efficiently capturing C4 alcohol aldehyde isomer volatile organic compounds using ionic liquid.

[0024] In the figure, there are absorption tower (T1), separator (T2), centrifugal pump 1 (P1), centrifugal pump (P2), heater (H1), and condenser (C1).

Detailed Embodiments

[0025] The following is further described in conjunction with the drawings, which does not limit the scope involved in the present invention.

[0026] Example 1:

[0027] The feed flow rate is 1000 kg / h, the feed contains 90% N2, and 2.5% (mass fraction) of NBA, NBU, IBA and IBU respectively. The number of theoretical plates in the absorption tower (T1) is 10. N2, NBA, NBU, IBA and IBU first enter the absorption tower (T1), and countercurrently contact with the absorbent [EMIM][TFO] in the absorption tower (T1). N2 is separated from the upper part of the absorption tower (T1), and the absorbent and NBA, NBU, IBA, IBU enter the separator (T2) from the lower part of the absorption tower (T2) through centrifugal pump 1 (P1) and heater (H2). In the separator (T2), NBA, NBU, IBA, IBU are separated from the upper part of the separator (T2). Waste heat recovery is carried out on the ILs stream after high-temperature and low-pressure desorption, and it is heat-exchanged with the VOCs-rich stream entering the separator (T2), with a heat load of 48.56 Kw. Part of the absorbent is cooled by the condenser (C1) and then refluxed to the separator (T2), and part of it returns to the absorption tower (T1) together with the heat exchanger (H2) and the supplementary absorbent. The mass fraction of the four VOCs is less than 0.02%, and the purity of the recycled ILs is greater than 99.9%.

[0028] Example 2:

[0029] The feed flow rate is 1000 kg / h, and the feed contains 90% N2, 2.5% each of NBA, NBU, IBA, and IBU (mass fraction). The number of theoretical plates in the absorption column (T1) is 10. N2, NBA, NBU, IBA, and IBU first enter the absorption column (T1) and contact countercurrently with the absorbent [EMIM][TFO] in the absorption column (T1). N2 is separated from the upper part of the absorption column (T1). The absorbent and NBA, NBU, IBA, and IBU enter the separator (T2) from the lower part of the absorption column (T2) via the centrifugal pump 1 (P1) and the heater (H2). In the separator (T2), NBA, NBU, IBA, and IBU are separated from the upper part of the separator (T2). The absorbent is cooled by the centrifugal pump 2 (P2) and the condenser (C1) and then returns to the absorption column (T1) together with the supplementary absorbent. The mass fraction of the four VOCs is less than 0.02%, and the purity of the recycled ILs is greater than 99.9%.

Claims

1. Provide a device for efficiently capturing four VOCs, NBA, NBU, IBA and IBU, using ionic liquids, including an ILs storage tank, a water supply pump, an absorption tower, an ILs storage tank containing VOCs, a gas chromatograph, a VOCs generator, and a VOCs storage tank; further described: high-purity N2 (99.999%) is precisely pressure-regulated by a pressure reducing valve, and then flow-calibrated by a mass flow controller, and then introduced into a generator containing a mixed solvent of VOCs in an equal molar ratio. The simulated exhaust gas carrying VOCs is introduced into the absorption tower through a distributed gas distribution system at the bottom of the tower. The absorbent is injected from the top of the tower at a specified flow rate through a constant-flow peristaltic pump to form a gas-liquid reverse micro-contact mass transfer process, and the system is maintained at (298.15±0.1)K through a precise temperature control system. The exhaust gas detection adopts an online gas chromatography analysis scheme: the periodically sampled gas phase components are introduced into the GC-2014C system through a six-way valve. The LabSolutions workstation was used to collect data and integrate peak areas, and the concentration of residual VOCs in the gas phase was quantitatively analyzed based on the external standard method. Three parallel determinations were set for each group of experiments, and the relative standard deviation was controlled within 2%.

2. Provide a method for efficiently capturing four VOCs, namely NBA, NBU, IBA, and IBU, characterized in that The device for capturing NBA, NBU, IBA and IBU mainly comprises the following parts: an absorption tower (T1), a separator (T2), a centrifugal pump 1 (P1), a centrifugal pump (P2), a heater (H1), a condenser (C1) and a heat exchanger (H2); N2 is separated at the top of the absorption tower (T1), and the mixture at the bottom of the tower flows through the centrifugal pump 1 (P1) and the heater (H1) and enters the separator (T2); the waste heat of the ILs stream after high-temperature and low-pressure desorption is recovered, and it is heat exchanged with the VOCs-rich stream entering the separator (T2), and the required VOCs are separated at the top of the separator (T2), and the bottom absorbent is condensed by the condenser (C1) and returned to the absorption tower (T1) through a pipeline with the replenished fresh absorbent.

3. According to claim 1, wherein A method for separating an azeotropic mixture of amyl alcohol-amyl formate-water by pressure swing distillation is as follows: NBA, NBU, IBA, IBU and N2 are introduced from the bottom of the absorption tower (T1), and the absorbent is introduced from the upper part of the absorption tower (T1) to contact with the gas in countercurrent. N2 is separated from the upper part of the absorption tower (T1), and the absorbent and NBA, NBU, IBA, IBU enter the separator (T2) from the lower part of the absorption tower (T2) through the centrifugal pump 1 (P1) and the heater (H2). In the separator (T2), NBA, NBU, IBA, IBU are separated from the upper part of the separator (T2), and the waste heat of the ILs stream after high-temperature and low-pressure desorption is recovered, and it is heat-exchanged with the VOCs-rich stream entering the separator (T2). A part of the absorbent is cooled by the condenser (C1) and then refluxed to the separator (T2), and a part of it is returned to the absorption tower (T1) together with the supplementary absorbent through the heat exchanger (H2). The operating pressure of the absorption tower (T1) is 5 atm, the number of theoretical plates is 10, and the heat exchanger power is 48.56 kW.

4. According to claim 1, it is characterized in that: The mass fractions of the four VOCs were less than 0.02%, and the purity of the recycled ILs was greater than 99.9%.

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