JP7590740B2 - Cyclohexyldiamine-based aqueous ionic solutions and their use in the absorption of sulfur dioxide. - Google Patents

Description

The present application relates to the technical field of the use of aqueous ionic solutions , in particular the use of aqueous ionic solutions based on cyclohexyl diamine in the field of absorbing sulfur dioxide in gases.

Pollution caused by sulfur dioxide emissions and acid rain has serious impacts on the ecological environment and human health, and controlling sulfur dioxide emissions in gas is the main task of air pollution control. Therefore, it is urgent to control and reduce sulfur dioxide gas emissions, and the development of new efficient and environmentally friendly materials and processes for capturing and recovering sulfur dioxide is of great importance.

Currently, the capture of sulfur dioxide gas using traditional processes such as limestone, ammonia, and organic solvents has advantages such as low cost, fast capture speed, and large capture volume. However, these types of trapping agents have problems such as the solvent being easily volatilized, being highly corrosive, producing large amounts of low-quality by-products, and being difficult to regenerate, and are not in line with the principles of sustainable development.

Ionic liquids have the characteristics of low vapor pressure, high thermal stability, stable chemical properties, and adjustable and controllable structure, and have attracted great attention from scientific researchers in various countries. The use of ionic liquids in the field of flue gas desulfurization has the advantages of high stability of the absorption liquid and good recycling performance. Many studies have been published on the absorption of sulfur dioxide by ionic liquids, mainly including guanidine-based ionic liquids , alcoholamine-based ionic liquids , pyridine-based ionic liquids , imidazole-based ionic liquids , ether-functionalized ionic liquids , and deep eutectic ionic liquids .

Although ionic liquids show good use prospects in absorbing sulfur dioxide, most ionic liquids have very high viscosity, which results in low mass and heat transfer efficiency, affecting the industrial use of ionic liquids . In addition, since sulfur dioxide-containing gases in practice usually contain water, the influence of water on the absorption performance of ionic liquids must be considered. According to the literature, water has a high affinity with most ionic liquids , and combines with ionic liquids to rapidly reduce the absorption of sulfur dioxide. In addition to water vapor, flue gas also contains oxygen. In the desulfurization process, sulfur dioxide is oxidized to produce sulfuric acid. The formation of sulfuric acid destroys the structure of the ionic liquid , rapidly reducing the absorption capacity of the ionic liquid and finally deactivating it. The disadvantages such as expensive raw material prices, too high viscosity, and poor stability of water limit the industrial use of traditional ionic liquids . Therefore, developing an ionic liquid desulfurization process with good efficiency, higher reversibility, and lower energy consumption applicability based on a renewable absorption process is an important development direction in the field of flue gas desulfurization of ionic liquids at present.

However, the current industrial methods for capturing sulfur dioxide gas using functionalized ionic liquids generally have problems such as insufficient capture capacity, high absorption enthalpy, difficult desorption, and poor recycling performance, which affect their industrial use.

The present application provides a cyclohexyldiamine-based ionic aqueous solution and its use, in which the ionic aqueous solution of the present application can absorb 0.78g/g of _SO2 saturated per gram of ionic aqueous solution , has low toxicity, is easy to synthesize, and is easy to prepare on a large scale. It can be used as an absorbent to efficiently absorb _SO2 , and is easy to desorb and recycle.

The structural formula of the cyclohexyldiamine ion aqueous solution of the present application is:
or
and
R ₁ and R ₂ are C _n H _2n (n is an integer, 0≦n≦4), and the anion is one or more of inorganic acid ions or organic acid ions.

The inorganic acid ion is one or more of NO ₃ ⁻ , Cl ⁻ or HSO ₃ ⁻ .

The organic acid ion is one or more of the following: phthalate ion, cyclohexanedicarboxylate ion, acrylate ion, methacrylate ion, formate ion, acetate ion, propionate ion, lactate ion, benzoate ion, methanesulfonate ion, trifluoroacetate ion, dichloroacetate ion, tartrate ion, citrate ion, methanesulfonate ion, malate ion, and ascorbate ion.

The cyclohexyldiamine-based ion aqueous solution of the present application can be used to absorb sulfur dioxide by mixing with water to form an absorption solution for sulfur dioxide in gas. The multi-site hydrogen bonding action between the multifunctional groups, such as amino groups, aldehyde groups, and hydroxyl groups, contained in the cyclohexyldiamine ion aqueous solution and _SO2 molecules realizes efficient absorption of _SO2 .

The process of absorbing _SO2 using the above-mentioned ionic aqueous solution is as follows: (1) contacting _SO2- containing gas with a pre-absorption absorbing solution containing a cyclohexyldiamine-based ionic aqueous solution and water to absorb the _SO2 in the gas and form an absorbing solution after absorption; (2) heating and/or depressurizing the absorbing solution after absorption to desorb and regenerate the absorbing solution, thereby generating the absorbing solution and gaseous sulfur dioxide by regeneration; (3) applying the absorbing solution regenerated in step (2) to step (1), and recycling steps (2) and (1) to realize the recycling of the absorbing solution.

In step (1), the temperature of the _SO2 in the gas to be absorbed is 5 to 80°C, and the pressure is 0.08 to 1 MPa.

The absorbent after absorption is heated to 70 to 150°C and the desorption pressure is 0.001 to 0.11 MPa to desorb _SO2 .

The absorbing liquid can be recycled by desorbing the sulfur dioxide through distillation to regenerate the absorbing liquid, and then returning it to an absorption tower or other absorption device.

The mass percentage of water in the absorption liquid before absorption is 5 to 95%.

In order to reduce the corrosion of the device during the absorption process, a corrosion inhibitor can be added to the absorption solution before absorption, and the weight ratio of the corrosion inhibitor to the absorption solution before absorption is 0.01 to 0.4. The corrosion inhibitor may be one or more of metal oxides or inorganic salts, such as chromates, dichromates, nitrates, nitrites, silicates, molybdates, tungstates, or sulfates.

The present application further claims an absorbing solution for sulfur dioxide containing said aqueous ionic solution , which may further contain other auxiliary substances that do not affect the absorbing effect.

By introducing various functional groups such as cyano, ether, amino and halogen into the anions and cations in the ionic aqueous solution, the ionic aqueous solution can be synthesized to meet specific requirements, so that the ionic aqueous solution can absorb _SO2 efficiently, reversibly and with low energy consumption. Through the structural design of the functionalized ionic aqueous solution , the present application not only improves the capture amount of the ionic aqueous solution , but also improves the desorption performance of the ionic aqueous solution , thereby achieving the capture of sulfur dioxide gas with large capacity and low energy consumption. Compared with the previously reported ionic aqueous solutions , the cyclohexyldiamine-based ionic aqueous solution has the advantages of simple synthesis process, low toxicity, and excellent decomposition.

The beneficial effects of the present invention are as follows:
The cyclohexyldiamine-based ionic aqueous solution in the method of the present application is not only low in toxicity, simple in synthesis process, and easy to prepare on a large scale, but also has low vapor pressure, low volatility, and little diffusion into the atmosphere, making it suitable as an absorbing solution. As an absorbing solution, it can achieve efficient absorption of _SO2 through the multi-site hydrogen bonding action between amino groups, aldehyde groups, and hydroxyl groups and _SO2 molecules, and the saturated absorption amount of _SO2 per gram of ionic aqueous solution is as high as 0.78g/g. It can also be used to completely desorb _SO2 by heating or decompression to realize the regeneration of the absorbing solution, with good recyclability, and the regenerated absorbing solution can be recycled and has stable absorption performance. The absorbing solution has the advantages of simple synthesis, low price, low viscosity, good stability, high _SO2 absorption, easy desorption, and recyclability, providing a new way for the purification and separation of _SO2 .

The technical solution of the present application will be further described below with reference to specific embodiments. Those skilled in the art should understand that the following examples are merely intended to aid in the understanding of the present application and should not be considered as specific limitations on the present application.

Example 1
58.57 g of 1,3-cyclohexanedimethaneamine and 58.5 g of water were added to the flask, and 37.09 g of lactic acid and 40.39 g of sulfuric acid were added to the constant pressure dropping funnel, and the mixture was slowly titrated at room temperature. After the titration was completed, the temperature was raised to 80°C and the reaction was continued for 3 hours, after which the reaction was terminated. The aqueous ionic solution prepared by the reaction was a pale yellow liquid with good fluidity.

The above ionic aqueous solution and water were mixed and diluted at a volume ratio of 1:1, and 5 ml of the diluted ionic aqueous solution was taken and placed in a reaction flask as an absorbing solution. The gas flow rate was adjusted to 50 ml/min, and _SO2 gas was introduced into the reaction flask. During the absorption process, the mass of the absorbing solution was measured every minute, and the experiment was stopped after absorbing for 30 minutes. The saturated absorption amount of _SO2 per gram of the ionic aqueous solution was 0.67 g/g.

Example 2
55.72 g of 1,3-cyclohexanedimethaneamine and 55.7 g of water were added to the flask, and 70.57 g of lactic acid was added to the constant pressure dropping funnel so that the molar ratio of 1,3-cyclohexanedimethaneamine to lactic acid was 1:2. The mixture was slowly titrated at room temperature, and after the titration was completed, the temperature was raised to 80°C and the reaction was continued for about 3 hours, after which the reaction was completed. The aqueous ionic solution prepared by the reaction was a deep yellow liquid with good fluidity.

The above ionic aqueous solution and water were mixed and diluted at a volume ratio of 1:1, and 5 ml of the diluted ionic aqueous solution was taken and placed in a reaction flask as an absorbing solution. The gas flow rate was adjusted to 50 ml/min, and _SO2 gas was introduced into the reaction flask. During the absorption process, the mass of the absorbing solution was measured every minute, and the experiment was stopped after absorbing for 30 minutes. The saturated absorption amount of _SO2 per gram of the ionic aqueous solution was 0.52 g/g.

Example 3
Add 17.13g of malic acid to the flask, and react 1,4-cyclohexanedimethaneamine with malic acid in a molar ratio of 1:1. Weigh out 18.17g of 1,4-cyclohexanedimethaneamine, add twice the amount of water (36.34g) and mix evenly. Add to the flask, stir and heat, and increase the temperature to 80°C. At this time, the malic acid gradually dissolves. After stirring and reacting at 80°C for 3 hours, the reaction is completed. The ionic aqueous solution is pale yellow, has good fluidity and low viscosity.

The ionic aqueous solution and water were mixed and diluted at a volume ratio of 1:1, and 5 ml of the diluted ionic aqueous solution was taken and placed in a reaction flask as an absorbing solution. The gas flow rate was adjusted to 50 ml/min, and _SO2 gas was introduced into the reaction flask. During the absorption process, the mass of the absorbing solution was measured every minute, and the experiment was stopped after absorbing for 30 minutes. The saturated absorption amount of _SO2 per gram of the ionic aqueous solution was 0.46 g/g.

Example 4
Add 22.24g of malic acid to the flask, and react 1,3-cyclohexanedimethaneamine with malic acid in a molar ratio of 1:1. Weigh out 23.59g of 1,3-cyclohexanedimethaneamine, add twice the amount of water (47.18g) and mix evenly. Add to the flask, stir and heat, and increase the temperature to 80°C. At this time, the malic acid gradually dissolves. After stirring and reacting at 80°C for 3 hours, the reaction is completed. The ionic aqueous solution is pale yellow, has good fluidity and low viscosity.

The above ionic aqueous solution and water were mixed and diluted at a volume ratio of 1:1, and 5 ml of the diluted ionic aqueous solution was taken and placed in a reaction flask as an absorbing solution. The gas flow rate was adjusted to 50 ml/min, and _SO2 gas was introduced into the reaction flask. During the absorption process, the mass of the absorbing solution was measured every minute, and the experiment was stopped after absorbing for 30 minutes. The saturated absorption amount of _SO2 per gram of the ionic aqueous solution was 0.71 g/g.

Example 5
70.45 g of 1,4-cyclohexanedimethaneamine and 70 g of water were added to the flask, and 85.28 g of methacrylic acid was added to the constant pressure dropping funnel so that the molar ratio of 1,4-cyclohexanedimethaneamine to methacrylic acid was 1:2. The reaction was slowly titrated at room temperature, with a small amount of heat being released during the reaction, and the temperature of the reactant rose to about 36°C. After the titration, the temperature was raised to 80°C and the reaction was continued for about 3 hours, after which it was terminated. A pale yellow ion aqueous solution with good fluidity was prepared by the reaction.

The above ionic aqueous solution and water were mixed and diluted at a volume ratio of 1:1, and 5 ml of the diluted ionic aqueous solution was taken and placed in a reaction flask as an absorbing solution. The gas flow rate was adjusted to 50 ml/min, and _SO2 gas was introduced into the reaction flask. During the absorption process, the mass of the absorbing solution was measured every minute, and the experiment was stopped after absorbing for 30 minutes. The saturated absorption amount of _SO2 per gram of the ionic aqueous solution was 0.78 g/g.

Example 6
The absorption liquid in Example 2 that absorbed _SO2 until it became saturated was taken, and was subjected to total reflux distillation at normal pressure and 105°C for 3 hours, and then cooled. According to the absorption conditions in Example 1, the gas flow rate was adjusted to 50ml/min, and _SO2 gas was introduced into the reaction flask. During the absorption process, the mass of the absorption liquid was measured every minute, and the experiment was stopped after absorbing for 30 minutes, and the _SO2 saturated absorption amount per gram of the ionic aqueous solution was calculated. The _SO2 saturated absorption amount per gram of the ionic aqueous solution that was repeated six times is shown in the table below.

Example 7
64.33 g of 1-aminomethyl-3-aminoethyl-cyclohexane and 58.5 g of water were added to the flask, and 74.29 g of lactic acid was added to the constant pressure dropping funnel so that the molar ratio of 1-aminomethyl-3-aminoethyl-cyclohexane to lactic acid was 1:2. The mixture was slowly titrated at room temperature, and after the titration was completed, the temperature was raised to 80°C and the reaction was continued for 3 hours, after which the reaction was completed. The aqueous ionic solution prepared by the reaction was a pale yellow liquid with good fluidity.

The ionic aqueous solution and water were mixed and diluted at a volume ratio of 1:1, and 5 ml of the diluted ionic aqueous solution was taken and placed in a reaction flask as an absorbing solution. The gas flow rate was adjusted to 50 ml/min, and _SO2 gas was introduced into the reaction flask. During the absorption process, the mass of the absorbing solution was measured every minute, and the experiment was stopped after absorbing for 30 minutes. The saturated absorption amount of _SO2 per gram of the ionic aqueous solution was 0.66 g/g.

Example 8
55.72 g of 1,4-cyclohexanedimethaneamine and 55.7 g of water were added to the flask, and 35.29 g of lactic acid and 47.83 g of benzoic acid were added to the constant pressure dropping funnel, and the titration was slowly carried out at room temperature. After the titration was completed, the temperature was raised to 80°C and the reaction was continued for about 3 hours, after which the reaction was completed. The aqueous ionic solution prepared by the reaction was a deep yellow liquid with good fluidity.

The above ionic aqueous solution and water were mixed and diluted at a volume ratio of 1:1, and 5 ml of the diluted ionic aqueous solution was taken and placed in a reaction flask as an absorbing solution. The gas flow rate was adjusted to 50 ml/min, and _SO2 gas was introduced into the reaction flask. During the absorption process, the mass of the absorbing solution was measured every minute, and the experiment was stopped after absorbing for 30 minutes. The saturated absorption amount of _SO2 per gram of the ionic aqueous solution was 0.53 g/g.

Example 9
58.57 g of 1,3-cyclohexanedimethaneamine and 58.5 g of water were added to the flask, and 51.89 g of nitric acid was added to the constant pressure dropping funnel and slowly titrated at room temperature. After the titration was completed, the temperature was raised to 80°C and the reaction was continued for 3 hours, after which the reaction was terminated. The aqueous ionic solution prepared by the reaction was a pale yellow liquid with good fluidity.

The above ionic aqueous solution and water were mixed and diluted at a volume ratio of 1:1, and 5 ml of the diluted ionic aqueous solution was taken and put into a reaction flask as an absorbing solution, and sodium nitrate was added as a corrosion inhibitor at a weight ratio of 0.1% of the absorbing solution, and the gas flow rate was adjusted to 50 ml/min. _SO2 gas was introduced into the reaction flask, and the mass of the absorbing solution was measured every minute during the absorption process, and the experiment was stopped after absorbing for 30 minutes. The saturated absorption amount of _SO2 per gram of the ionic aqueous solution was 0.65 g/g.

Although the present application has described the preparation method and use of the functionalized ion aqueous solution for absorbing sulfur dioxide (SO ₂ ) in the gas of the present application through the above examples, the applicant declares that the present application is not limited to the above process sequence, i.e., it does not mean that the present application can be carried out only by the above process sequence.

Claims (8)

A cyclohexyldiamine ion aqueous solution, the structural formula of the cyclohexyldiamine ion as a solute is:
or
A cyclohexyldiamine- based ion aqueous solution . 2. Use of the aqueous cyclohexyldiamine ion solution according to claim 1 in absorbing sulfur dioxide. The use of the aqueous cyclohexyldiamine ion solution according to claim _{2 in absorbing sulfur dioxide, comprising: a step (1) of contacting an SO 2-} containing gas with an absorbing solution before absorption containing an aqueous cyclohexyldiamine ion solution to absorb the SO ₂ in the gas to form an absorbing solution after absorption; a step (2) of heating and/or depressurizing the absorbing solution after absorption to desorb and regenerate the absorbing solution; and a step (3) of applying the absorbing solution regenerated in step (2) to step (1), and recycling step (2) and step (1) to realize recycling of the absorbing solution. The use of the aqueous cyclohexyldiamine ion solution according to claim 3 in absorbing sulfur dioxide, wherein in step (1), the temperature of the _SO2 in the gas to be absorbed is 5-80°C and the pressure is 0.08-1 MPa. The use of the aqueous cyclohexyldiamine ion solution according to claim 3 in absorbing sulfur dioxide, wherein the absorption liquid after absorption is desorbed from SO ₂ at 70 to 150 ° C., and the desorption pressure is 0.001 to 0.11 MPa. 4. Use of the aqueous cyclohexyldiamine ion solution according to claim 3 in absorbing sulfur dioxide, wherein the mass percentage of water in the absorbing solution before absorption is 5 to 95%. The use of the aqueous cyclohexyldiamine ion solution according to claim 3 in absorbing sulfur dioxide, wherein the absorption solution before absorption further comprises a corrosion inhibitor, the weight ratio of the corrosion inhibitor to the absorption solution before absorption is 0.01-0.4, and the corrosion inhibitor is one or more of chromate, dichromate, nitrate, nitrite, silicate, molybdate , tungstate or sulfate. A sulfur dioxide absorbing solution comprising the cyclohexyldiamine ion aqueous solution according to claim 1.