Anhydrous solvent for capturing carbon dioxide as well as preparation method and application of anhydrous solvent

Abstract

The invention belongs to the technical field of gas separation, and relates to an anhydrous solvent for carbon dioxide capture and a preparation method and application thereof. The anhydrous solvent provided by the invention is composed of effective components and auxiliaries, wherein the effective components are diethanol amine, N-methyldiethanol amine, ethanol amine, piperazine, diglycolamine, N-methylmonoethanol amine and ethylene glycol; the auxiliaries are a corrosion inhibitor, an antioxidant and a defoaming agent. Compared with an alcohol amine aqueous solution, the anhydrous solvent provided by the invention has stronger absorption capacity when being used for absorbing carbon dioxide, and shows better stability and higher absorption speed.

Description

Technical Field

[0001] The present invention belongs to the technical field of gas separation, and relates to an anhydrous solvent for capturing carbon dioxide, and a preparation method and application thereof. Background Art

[0002] Existing carbon dioxide capture and recovery technologies include physical methods, chemical methods, and biological methods. The chemical method includes a variety of technologies, such as chemical fixation technology, chemical absorption method, chemical adsorption method, membrane separation method, and carbon dioxide recombination method. Among them, the chemical absorption method is the separation and absorption method with the lowest cost. Compared with other methods, the organic amine method has the characteristics of large absorption capacity, good absorption effect, low cost, recyclable absorbent, and high-purity product recovery. The molecular structure of organic alcohol amine compounds contains at least one hydroxyl group that has the function of reducing the vapor pressure of the compound and providing the necessary alkalinity for the aqueous solution, as well as an amino group that can promote the absorption of acidic gas components. The absorption of CO2 by organic amine aqueous solution is mainly due to the presence of nitrogen atoms in the amine molecules. The amine dissociates in the aqueous solution, making the solution alkaline, and is easy to react with acidic gases such as CO2 to achieve the purpose of removing and recovering CO2. According to the number of "active" hydrogen atoms connected to the nitrogen atom of the amino group, alcoholamine molecules can be divided into three categories: primary alcoholamines (such as monoethanolamine, abbreviated as MEA; diglycolamine, abbreviated as DGA), secondary alcoholamines (such as diethanolamine, abbreviated as DEA; diisopropanolamine, abbreviated as DIPA) and tertiary alcoholamines (such as triethanolamine, abbreviated as TEA; N-methyldiethanolamine, abbreviated as MDEA).

[0003] In actual industrial applications, the monoethanolamine (MEA) solution method and the diethanolamine (DEA) solution method are relatively mature in technology. The characteristics of MEA and DEA solutions for enriching carbon dioxide are fast absorption speed, but they are easy to corrode equipment and easy to degrade. Triethanolamine (TEA) and N-methyldiethanolamine (MDEA) solutions are gradually attracting attention for absorbing carbon dioxide. MDEA and TEA have good stability, large load capacity, small regeneration heat, and basically no corrosion to equipment. Their disadvantage is that the absorption rate is relatively low. Adding a small amount of primary alcoholamine and secondary alcoholamine to the tertiary alcoholamine solvent can significantly increase the reaction rate of tertiary alcoholamine. Therefore, it is particularly important to select a suitable activator according to the characteristics of tertiary alcoholamine. Piperazine (PZ), also known as diazinon, is one of the more commonly used activators. In addition, amine compounds such as 1,4-butanediamine (BDA), N-methyl-1,3-diaminopropane (MAPA), hexamethylenediamine (HMDA), diethylenetriamine (DETA) and triethylenetetramine (TETA) are often used as activators because they contain multiple primary amine or swollen amine nitrogen atoms in one molecule, which greatly increases the solvent loading and reaction rate. The use of alcohol amine aqueous solution to absorb carbon dioxide is a relatively mature process, but it still faces problems such as the large impact of temperature on the reaction system, easy equipment corrosion, low reuse rate, and the inability to achieve both absorption rate and absorption amount. Summary of the invention

[0004] The purpose of the present invention is to provide an anhydrous solvent for carbon dioxide capture, which solves the problems of large temperature influence on the reaction system, easy equipment corrosion, low reuse rate, and inability to achieve both absorption rate and absorption amount in the process of absorbing carbon dioxide with alcohol amine aqueous solution. The present invention adopts an anhydrous solvent, which has relatively lower heat capacity and vapor pressure and relatively higher boiling point than aqueous solution, thereby reducing regeneration energy consumption and solvent loss.

[0005] On the one hand, the present invention relates to an anhydrous solvent for carbon dioxide capture, wherein the effective ingredients of the anhydrous solvent are diethanolamine (DEA), N-methyldiethanolamine (MDEA), ethanolamine (MEA), piperazine (PZ), diglycolamine (DGA), N-methylmonoethanolamine (MMEA) and ethylene glycol.

[0006] Specifically, in the anhydrous solvent for carbon dioxide capture provided by the present invention, the main absorbent is diethanolamine, N-methyldiethanolamine, ethanolamine, diglycolamine, and N-methylmonoethanolamine, which plays a major role in absorbing carbon dioxide; the auxiliary absorbent (or activator) is piperazine, which plays a role in increasing the reaction rate of the main absorbent.

[0007] Those skilled in the art should know that the kinetics of the single reaction of CO2 and alcohol amine compounds have been widely studied. Adding a small amount of primary alcohol amine and secondary alcohol amine to the tertiary alcohol amine solvent can significantly increase the reaction rate of the tertiary alcohol amine. However, the effect of mixing multiple alcohol amine compounds for absorbing carbon dioxide is difficult to predict. Because there are many theoretical models for explaining the chemical absorption of carbon dioxide by alcohol amine aqueous solution, such as the dual model theory, the permeation model theory and the surface renewal theory model, there is no research model for non-aqueous solution.

[0008] Furthermore, in the anhydrous solvent for carbon dioxide capture provided by the present invention, the anhydrous solvent is composed of the active ingredients and auxiliary agents, and the auxiliary agents are corrosion inhibitors, antioxidants and defoaming agents.

[0009] Specifically, in the anhydrous solvent for carbon dioxide capture provided by the present invention, the role of the corrosion inhibitor is to slow down the corrosion rate of the anhydrous solvent on the equipment in use, thereby extending the service life of the equipment; the role of the antioxidant is to slow down the oxidative degradation rate of the anhydrous solvent; the role of the defoaming agent is to reduce and eliminate foam, thereby improving the stability of the equipment operation.

[0010] Furthermore, in the anhydrous solvent for carbon dioxide capture provided by the present invention, the corrosion inhibitor is a surface adsorption type corrosion inhibitor, the antioxidant is a metal oxide antioxidant, and the defoamer is a silicone type defoamer.

[0011] Furthermore, in the anhydrous solvent for carbon dioxide capture provided by the present invention, the surface adsorption type corrosion inhibitor is selected from SW-ODM, dodecylamine or octadecylamine, the metal oxide antioxidant is selected from sodium metavanadate, titanium oxide or cerium oxide, and the silicone type defoamer is selected from dimethyl silicone oil, XIAMETER TM AFE-1410 or XIAMETE TM OFX-5330Fluid.

[0012] Preferably, in the anhydrous solvent for carbon dioxide capture provided by the present invention, the surface adsorption type corrosion inhibitor is SW-ODM, the metal oxide antioxidant is sodium metavanadate, and the organosilicon type defoamer is XIAMETE TM OFX-5330 Fluid.

[0013] Furthermore, in the anhydrous solvent for carbon dioxide capture provided by the present invention, the solvent is composed, by mass percentage, of 12-18% diethanolamine, 8-12% N-methyldiethanolamine, 18-24% ethanolamine, 8-12% piperazine, 5-10% diglycolamine, 5-10% N-methylmonoethanolamine, 0.01-0.1% corrosion inhibitor, 0.5-1% antioxidant, 0.8-1.2% defoaming agent and the remainder ethylene glycol.

[0014] Illustratively, in the anhydrous solvent for carbon dioxide capture provided by the present invention, corrosion inhibitors, antioxidants and defoamers are auxiliary ingredients, and those skilled in the art can selectively add them during implementation. For example, the defoamer is generally added when the anhydrous solvent shows signs of bubbles, and can also be added together with the anhydrous solvent at the initial stage of use.

[0015] Illustratively, in the anhydrous solvent for carbon dioxide capture provided by the present invention, no corrosion inhibitor, antioxidant and defoaming agent are added, and the components of the anhydrous solvent are, by mass percentage, 12-18% of diethanolamine, 8-12% of N-methyldiethanolamine, 18-24% of ethanolamine, 8-12% of piperazine, 5-10% of diglycolamine, 5-10% of N-methylmonoethanolamine and the remainder of ethylene glycol.

[0016] Furthermore, in the anhydrous solvent for carbon dioxide capture provided by the present invention, the solvent is composed, by mass percentage, of 15% diethanolamine, 10% N-methyldiethanolamine, 20% ethanolamine, 10% piperazine, 7% diglycolamine, 8% N-methylmonoethanolamine, 0.05% corrosion inhibitor, 0.75% antioxidant, 0.1% defoaming agent and the remainder ethylene glycol.

[0017] On the other hand, the present invention relates to a method for preparing an anhydrous solvent for carbon dioxide capture, the preparation of the anhydrous solvent for carbon dioxide capture comprising: mixing diethanolamine, N-methyldiethanolamine, ethanolamine, diglycolamine, N-methylmonoethanolamine and ethylene glycol, heating to above 30°C to obtain a uniform liquid, and then adding piperazine to mix evenly.

[0018] In another aspect, the present invention relates to the use of the anhydrous solvent for carbon dioxide capture in absorbing carbon dioxide.

[0019] Furthermore, in the application provided by the present invention, the anhydrous solvent for carbon dioxide capture is used without adding water.

[0020] Compared with the prior art, the technical solution provided by the present invention has at least the following beneficial effects or advantages: The present invention uses a main absorbent composed of specific primary alcohol amines, secondary alcohol amines, tertiary alcohol amines and polyamine compounds for carbon dioxide capture. As an anhydrous solvent, it has a relatively low heat capacity and vapor pressure and a relatively high boiling point compared with an aqueous solution, thereby reducing regeneration energy consumption and solvent loss. In addition, when the anhydrous solvent provided by the present invention is used for carbon dioxide capture, the temperature has little effect on the reaction system, the equipment has low corrosiveness, the reuse rate is high, and both the absorption rate and the absorption amount are taken into account. DETAILED DESCRIPTION

[0021] The technical scheme of the present invention is described below in conjunction with the examples, but the present invention is not limited to the following examples. The experimental methods and detection methods described in each example are conventional methods unless otherwise specified; the reagents and materials are available on the market unless otherwise specified, and the % in the following examples are all mass percentages unless otherwise specified.

[0022] Example 1: This example provides a method for preparing an anhydrous solvent for carbon dioxide capture.

[0023] In terms of mass percentage, 12% of diethanolamine, 8% of N-methyldiethanolamine, 18% of ethanolamine, 8% of piperazine, 5% of diglycolamine, 5% of N-methylmonoethanolamine and the balance of ethylene glycol are taken.

[0024] In a water bath, diethanolamine, N-methyldiethanolamine, ethanolamine, diglycolamine, N-methylmonoethanolamine and ethylene glycol were mixed, heated to 30°C to obtain a uniform liquid, and piperazine was added after cooling and mixed evenly.

[0025] Example 2: This example provides a method for preparing an anhydrous solvent for carbon dioxide capture.

[0026] In terms of mass percentage, take 18% of diethanolamine, 12% of N-methyldiethanolamine, 24% of ethanolamine, 12% of piperazine, 10% of diglycolamine, 10% of N-methylmonoethanolamine and the balance of ethylene glycol.

[0027] In a water bath, diethanolamine, N-methyldiethanolamine, ethanolamine, diglycolamine, N-methylmonoethanolamine and ethylene glycol were mixed, heated to 40°C to obtain a uniform liquid, and piperazine was added after cooling and mixed evenly.

[0028] Example 3: This example provides a preparation of an anhydrous solvent for carbon dioxide capture.

[0029] In terms of mass percentage, 15% of diethanolamine, 10% of N-methyldiethanolamine, 20% of ethanolamine, 10% of piperazine, 7% of diglycolamine, 8% of N-methylmonoethanolamine and the balance of ethylene glycol are taken.

[0030] In a water bath, diethanolamine, N-methyldiethanolamine, ethanolamine, diglycolamine, N-methylmonoethanolamine and ethylene glycol were mixed, heated to 40°C to obtain a uniform liquid, and piperazine was added after cooling and mixed evenly.

[0031] Comparative Example 1: This comparative example is a composite organic alcohol amine aqueous solution conventionally used for carbon dioxide capture.

[0032] In terms of mass percentage, take 10% monoethanolamine, 10% triethanolamine and the remainder water.

[0033] After monoethanolamine and triethanolamine are evenly mixed, add water and stir evenly.

[0034] Comparative Example 2: This comparative example is intended to illustrate the effect of component replacement on performance provided in this application. This comparative example is the same as Example 3, except that diisopropanolamine, which is also a secondary alcohol amine, is used to replace diethanolamine.

[0035] Test Example 1: This test example is used to test the absorption effect of the liquids provided in Examples 1 to 3 and Comparative Examples 1 to 2 on CO2.

[0036] The gas absorption device used in the test consists of three parts: a cylinder gas supply system, a gas absorption reaction system and a measurement system. The gas absorption reaction system consists of a buffer kettle, an absorption kettle and a constant temperature water bath. The exterior of the gas buffer kettle and the absorption kettle are both made of stainless steel, and the lining material of the inner wall is polytetrafluoroethylene. The straight, three-way, four-way and ball valves used to connect the pipelines are all made of 304 stainless steel and connected by ferrules. The buffer kettle and the absorption kettle in the device are connected to pressure sensors, and the gas change is calculated by reading the change in pressure value. The temperature in the two kettles is read by temperature sensors inserted into the kettles respectively. The pressure sensor and the temperature sensor are both connected to a paperless recorder, and the readings can be directly read on the electronic screen.

[0037] The gas absorption device must be tested for air tightness before each experiment. The specific testing method is as follows: open the ball valve, first evacuate the entire device to a vacuum degree of 0.001Mpa. Then close the ball valve at the outlet of the vacuum pump, open the ball valve at the outlet of the CO2 cylinder, and slowly introduce CO2 gas into the system to a pressure of 0.6Mpa; close the ball valve at the outlet of the CO2 cylinder, and observe the changes in the pressure reading displayed on the paperless recorder. If the pressure does not change within 2 hours, it indicates that the air tightness of the device is good. If the pressure reading decreases, the leaking part of the device must be re-tested.

[0038] The device is used to measure the solubility of CO2 in the liquid provided in Examples 1 to 3 and Comparative Examples 1 to 2 at different temperatures. The test steps are as follows: 1. Turn on the weighing device, weigh the empty beaker, and pour the liquid to be tested into the empty beaker, about four-fifths of the liquid. 2. Fix the stirring rod, thermocouple, and CO2 vent tube, and record the original weight. 3. Turn on the agitator and temperature control system, keep the agitator speed unchanged, and set the required temperature for measurement. 4. Turn off the stirring after reaching the required temperature, and read the balance reading after the balance reading stabilizes. 5. Repeat step 3, open the CO2 valve, and control the bubbles to five or six per second. 6. Record the weight of the balance every 15 minutes, and turn off the stirring and CO2 vent tube before recording. 7. Until the weight no longer increases, it means that CO2 absorption has reached saturation. 8. Other temperatures are as shown in the above steps. In order to prevent the influence of the absorption of CO2 solvent at the previous temperature on the next temperature, the solution required for each temperature to be measured is a reconfigured solution, and the determination method of other solutions to be measured is similar. Under normal pressure conditions, the absorption capacities of the liquids provided in Examples 1 to 3 and Comparative Examples 1 to 2 at 25° C., 35° C. and 45° C. are measured as shown in Table 1.

[0039] Table 1: CO2 absorption capacity of different liquids at different temperatures (unit: mol / mol)

[0040] Temperature has two effects on the reaction system: on the one hand, temperature positively affects the reaction activation energy and reaction rate constant; on the other hand, too high temperature will lead to volatilization loss of the absorbent, affecting the absorption effect. The temperature of the coal-fired flue gas in the power plant is about 45~55℃, so the absorbent is required to maintain stability and good absorption at higher temperatures. As can be seen from Table 1, the liquids prepared in Examples 1~3 will have a reduced absorption capacity as the temperature rises within the temperature range of 25~45℃, but the effect is not very obvious, so it can be judged that the system is relatively stable in absorbing CO2.

[0041] In addition to having a large absorption capacity, an absorbent with excellent performance should also have the ability to be recycled. The definition of CO2 regeneration efficiency is: the ratio of the CO2 absorption capacity of the solution after regeneration to the absorption capacity of the fresh absorbent.

[0042] After the composite solution provided in Examples 1 to 3 and Comparative Example 1 has completed one absorption saturation in the absorption device, the sample is taken out and placed in the desorption device, vacuum dried at 110°C, and its weight is weighed to keep constant, indicating that the absorption and desorption have been completed, and then placed in the absorption device for the next absorption capacity measurement. After 4 cycles, the regeneration efficiency of CO2 is measured as shown in Table 2.

[0043] Table 2: CO2 regeneration efficiency (normal temperature and pressure)

[0044] As can be seen from Table 2, the regeneration efficiency of the liquids prepared in Examples 1 to 3 after four regenerations can still reach more than 97%, while the regeneration efficiency of the conventional composite organic alcohol amine aqueous solution is about 80%, indicating that the adsorption-desorption of the composite solution is a reversible process and has a higher regeneration efficiency.

[0045] Example 4: This example provides a preparation of an anhydrous solvent for carbon dioxide capture.

[0046] In terms of mass percentage, take 12% diethanolamine, 8% N-methyldiethanolamine, 18% ethanolamine, 8% piperazine, 5% diglycolamine, 5% N-methylmonoethanolamine, 0.01% dodecylamine, 0.5% titanium oxide, 0.8% dimethyl silicone oil and the balance ethylene glycol.

[0047] In a water bath, diethanolamine, N-methyldiethanolamine, ethanolamine, diglycolamine, N-methylmonoethanolamine and ethylene glycol were mixed, and heated to 30°C to obtain a uniform liquid. After cooling, piperazine, dodecylamine, titanium oxide and dimethyl silicone oil were added and mixed evenly.

[0048] Example 5: This example provides a preparation of an anhydrous solvent for carbon dioxide capture.

[0049] In terms of mass percentage, the following ingredients were used: 18% diethanolamine, 12% N-methyldiethanolamine, 24% ethanolamine, 12% piperazine, 10% diglycolamine, 10% N-methylmonoethanolamine, 0.1% octadecylamine, 1% cerium oxide, and XIAMETER TM AFE-1410 1.2% and ethylene glycol balance.

[0050] In a water bath, diethanolamine, N-methyldiethanolamine, ethanolamine, diglycolamine, N-methylmonoethanolamine and ethylene glycol were mixed and heated to 40°C to obtain a uniform liquid. After cooling, piperazine, octadecylamine, cerium oxide and XIAMETER TM AFE-1410 is mixed evenly.

[0051] Example 6: This example provides a preparation of an anhydrous solvent for carbon dioxide capture.

[0052] In terms of mass percentage, diethanolamine 15%, N-methyldiethanolamine 10%, ethanolamine 20%, piperazine 10%, diglycolamine 7%, N-methylmonoethanolamine 8%, SW-ODM 0.05%, sodium metavanadate 0.75%, XIAMETE TM OFX-5330 Fluid 0.1% and ethylene glycol balance.

[0053] In a water bath, diethanolamine, N-methyldiethanolamine, ethanolamine, diglycolamine, N-methylmonoethanolamine and ethylene glycol were mixed and heated to 40°C to obtain a uniform liquid. After cooling, piperazine, SW-ODM and XIAMETE TM OFX-5330 Fluid is mixed evenly.

[0054] Comparative Example 3: This comparative example is a composite organic alcohol amine aqueous solution conventionally used for carbon dioxide capture.

[0055] In terms of mass percentage, 10% monoethanolamine, 10% triethanolamine, 0.05% SW-ODM, 0.75% sodium metavanadate, and XIAMETE TM OFX-5330 Fluid 0.1% and water balance.

[0056] Mix the above components except water evenly, then add water and stir evenly.

[0057] The hanging plate method was used to hang 304 stainless steel and the weight loss of the steel plate was tested regularly to obtain the corrosion rate of the sample, expressed in mm / year. The test results are shown in Table 3.

[0058] Table 3: Corrosion rate and CO2 absorption capacity

[0059] As can be seen from Table 3, the corrosion rate of the liquids prepared in Examples 4 to 6 on 304 stainless steel is 0.01 to 0.02 mm / year, which is significantly lower than the corrosion rate of the conventional composite organic alcohol amine aqueous solution (Comparative Example 3), indicating that the anhydrous solvent for carbon dioxide capture prepared in the present invention has a high CO2 absorption capacity and low corrosion to equipment.

[0060] The embodiments described above are part of the embodiments of the present invention, but not all of them. The detailed description of the embodiments of the present invention is not intended to limit the scope of the invention claimed for protection, but only represents selected embodiments of the present invention. All other embodiments obtained without creative work and related deductions and substitutions made by ordinary technicians in the field under the conditions of the concept of the present invention belong to the scope of protection of the present invention.

Claims

1. An anhydrous solvent for carbon dioxide capture, characterized in that: The effective components of the anhydrous solvent are diethanolamine, N-methyldiethanolamine, ethanolamine, piperazine, diglycolamine, N-methylmonoethanolamine and ethylene glycol.

2. The anhydrous solvent for carbon dioxide capture according to claim 1, characterized in that: The anhydrous solvent is composed of the effective ingredients and auxiliary agents, and the auxiliary agents are corrosion inhibitors, antioxidants and defoamers.

3. The anhydrous solvent for carbon dioxide capture according to claim 2, characterized in that: The corrosion inhibitor is a surface adsorption type corrosion inhibitor, the antioxidant is a metal oxide antioxidant, and the defoamer is an organosilicon type defoamer.

4. The anhydrous solvent for carbon dioxide capture according to claim 3, characterized in that: The surface adsorption type corrosion inhibitor is selected from SW-ODM, dodecylamine or octadecylamine, the metal oxide antioxidant is selected from sodium metavanadate, titanium oxide or cerium oxide, and the silicone type defoamer is selected from dimethyl silicone oil, XIAMETER TM AFE-1410 or XIAMETE TM OFX-5330 Fluid.

5. The anhydrous solvent for carbon dioxide capture according to claim 2, characterized in that: Calculated by mass percentage, it is composed of 12-18% of diethanolamine, 8-12% of N-methyldiethanolamine, 18-24% of ethanolamine, 8-12% of piperazine, 5-10% of diglycolamine, 5-10% of N-methylmonoethanolamine, 0.01-0.1% of corrosion inhibitor, 0.5-1% of antioxidant, 0.8-1.2% of defoaming agent and the balance of ethylene glycol.

6. The anhydrous solvent for carbon dioxide capture according to claim 5, characterized in that: Calculated by mass percentage, it consists of 15% diethanolamine, 10% N-methyldiethanolamine, 20% ethanolamine, 10% piperazine, 7% diglycolamine, 8% N-methylmonoethanolamine, 0.05% corrosion inhibitor, 0.75% antioxidant, 0.1% defoaming agent and the balance ethylene glycol.

7. A method for preparing an anhydrous solvent for carbon dioxide capture, characterized in that: The anhydrous solvent for carbon dioxide capture according to any one of claims 1 to 6 comprises: diethanolamine, N-methyldiethanolamine, ethanolamine, diglycolamine, N-methylmonoethanolamine and ethylene glycol are mixed and heated to above 30° C. to obtain a uniform liquid, and then piperazine is added and mixed evenly.

8. Use of the anhydrous solvent for carbon dioxide capture according to any one of claims 1 to 6 in absorbing carbon dioxide.

9. The use according to claim 8, characterized in that: The anhydrous solvent for carbon dioxide capture is used without adding water.

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