A method for desorbing CO2 using electric field-assisted alcohol amine

Abstract

The present invention relates to the field of alcohol amine decarbonization, and discloses a method for desorbing CO2 by using an electric field to assist alcohol amine. The method comprises the following steps: (1) contacting and mixing an alcohol amine absorbent with CO2 to obtain a rich liquid; (2) applying an external electric field to the rich liquid at a first preset temperature, and performing a desorption treatment at a second preset temperature to obtain a product CO2 gas and a regenerated alcohol amine absorbent; wherein the second preset temperature is 2-5°C lower than the first preset temperature; and the reaction voltage of the external electric field is 3-6V. The present invention provides a method for desorbing CO2 by using an electric field to assist alcohol amine, wherein an electric field is added to assist in enhanced desorption during the desorption process, and compared with a traditional heating desorption device, the method has the advantages of faster desorption rate, higher desorption efficiency, lower energy consumption, etc., and has simple steps, low cost, easy control of parameters, and obvious economic benefits.

Description

Technical Field

[0001] The invention relates to the field of alcohol amine decarbonization, and in particular to a method for utilizing electric field to assist alcohol amine in desorbing CO2. Background Art

[0002] The amine method in the chemical absorption method is one of the most widely used methods for CO2 capture industry. The chemical absorption method uses alkaline solution to contact with CO2 and react to generate unstable salt substances. The salts are reversely decomposed under certain conditions to release CO2 and regenerate the absorbent at the same time. Due to its high carbon dioxide treatment capacity, strong reliability and a lot of experience accumulated in engineering applications in the early stage, it is considered to be one of the most mature and commercially viable carbon capture technologies. At present, the traditional amine desorption technology is mainly heating desorption. The traditional heating desorption method is to make amine react with CO2 to generate salt and then heat it again to decompose it into amine absorption liquid and CO2. The decomposition reaction is a strong endothermic reaction, so the desorption process is accompanied by a lot of energy consumption. In addition, this technology has problems such as slow desorption speed, low desorption rate and solution loss caused by high regeneration temperature during heating desorption.

[0003] At present, various auxiliary methods are being studied to enhance the desorption of alcohol amines. Some literature uses thermal desorption process to desorb CO2 absorption rich liquid. Although thermal desorption is simple to operate, its desorption energy consumption is relatively high, and the energy consumption cost accounts for 70%-80% of the total cost. In addition, there is the problem that the absorbent is easily oxidized and degraded at high temperature. The desorption temperature of the decompression desorption process is low, and the desorption energy consumption is small, but its desorption efficiency is also relatively low.

[0004] CN 107596919A discloses a method for desorbing CO2 from an alcohol amine absorbent rich liquid by a membrane method. In the technical solution, a membrane method is used to desorb CO2 and absorb the rich liquid, so that the gas and liquid phases flow on both sides of the membrane without interfering with each other, thereby overcoming the problem of absorption liquid volatilization in the traditional thermal desorption process and saving energy consumption. However, the desorption effect of CO2 by this method still needs to be improved, and the method needs to add 5% dilute sulfuric acid to the rich liquid for detection, which will cause pollution to the alcohol amine absorbent and affect the reuse of the alcohol amine absorbent; in addition, since the method uses a polypropylene fiber membrane in the desorption process, the membrane will be contaminated during use and needs to be replaced regularly, which increases the cost and application difficulty during industrial application. Summary of the invention

[0005] The purpose of the present invention is to provide a method for desorbing CO2 by alcohol amine using an electric field. This method can not only improve the desorption efficiency and the desorption rate of CO2 while greatly reducing energy consumption, but also does not add other substances to pollute and damage the alcohol amine solution, and maintains the recycling performance of the alcohol amine.

[0006] In order to achieve the above object, the present invention provides a method for desorbing CO2 by using an electric field-assisted alcohol amine, the method comprising the following steps:

[0007] (1) contacting and mixing an alcohol amine absorbent with CO2 to obtain a rich liquid;

[0008] (2) applying an external electric field to the rich liquid at a first preset temperature, and performing a desorption treatment at a second preset temperature to obtain a product CO2 gas and a regenerated alcohol amine absorbent;

[0009] The second preset temperature is 2-5°C lower than the first preset temperature; and the reaction voltage of the external electric field is 3-6V.

[0010] The above technical solution of the present invention has at least the following advantages over the prior art:

[0011] (1) The present invention provides a method for desorbing CO2 by using an electric field to assist an amine, wherein an electric field is added during the desorption process to assist in enhancing the desorption. Compared with a conventional heating desorption device, the method has the advantages of faster desorption rate, higher desorption efficiency, lower energy consumption, etc., and has obvious economic benefits.

[0012] (2) The present invention provides a method for utilizing electric field to assist the desorption of CO2 by alcohol amine, which can ensure that the alcohol amine molecules in the alcohol amine absorbent do not undergo electrolysis, while promoting the migration and diffusion of carbamate salts generated by the reaction of alcohol amine molecules with carbon dioxide, thereby increasing the molecular collision rate and promoting the decomposition and regeneration of carbamate salts, thereby achieving the effect of improving the desorption rate.

[0013] (3) The present invention provides a method for desorbing CO2 using an electric field-assisted alcohol amine, which has simple steps, low cost, and easy-to-control parameters. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 4 is a graph showing the cyclic absorption results of the regenerated alcohol amine absorbent obtained in Example 1, Comparative Example 2 and Comparative Example 3 of the present invention after 4 cycles;

[0015] Figure 2 This is a graph showing the cyclic desorption results of the regenerated alcohol amine absorbent obtained in Example 1, Comparative Example 2, and Comparative Example 3 of the present invention after four cycles. DETAILED DESCRIPTION

[0016] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0017] In the present invention, "MDEA" means N-methyldiethanolamine, "TETA" means triethylenetetramine, and "PZ" and "anhydrous piperazine" mean p-diazepine.

[0018] As mentioned above, the present invention provides a method for desorbing CO2 using an electric field-assisted alcohol amine, the method comprising the following steps:

[0019] (1) contacting and mixing an alcohol amine absorbent with CO2 to obtain a rich liquid;

[0020] (2) applying an external electric field to the rich liquid at a first preset temperature, and performing a desorption treatment at a second preset temperature to obtain a product CO2 gas and a regenerated alcohol amine absorbent;

[0021] The second preset temperature is 2-5°C lower than the first preset temperature; and the reaction voltage of the external electric field is 3-6V.

[0022] During the research process, the inventors of the present invention discovered that, at a specific first preset temperature, an external electric field of a specific voltage is applied to the rich liquid obtained by contacting and mixing the alcoholamine absorbent with CO2, and the external electric field can promote the migration and diffusion of carbamate salts generated by the reaction of the alcoholamine absorbent and carbon dioxide in the rich liquid, thereby increasing the probability of collision between molecules and promoting the decomposition of more carbamate salts, thereby achieving the effect of enhanced desorption; in addition, during the application of the external electric field, the alcoholamine molecules of the alcoholamine absorbent are not electrolyzed, and the rich liquid is desorbed at a second preset temperature, and the regenerated alcoholamine absorbent obtained has good recycling capacity.

[0023] Preferably, in step (1), the mass ratio of the alcohol amine absorbent to the CO2 is 1:0.4-0.55. In this preferred case, the technical solution provided by the present invention can make the desorption rate of CO2 higher and the cost lower.

[0024] Preferably, in step (1), the alcohol amine absorbent is a mixture of N-methyldiethanolamine and water in a mass ratio of 1:2-7.

[0025] Preferably, in step (1), the alcohol amine absorbent is a mixture of triethylenetetramine and a polar solvent in a mass ratio of 1:2-6. In this preferred embodiment, the technical solution provided by the present invention can achieve a higher desorption rate of CO2.

[0026] More preferably, the polar solvent is water.

[0027] Preferably, in step (1), the alcohol amine absorbent is a mixture of N-methyldiethanolamine and p-diazepine in a mass ratio of 4-7:1.

[0028] Preferably, in step (1), the contact mixing conditions include: temperature of 20-40° C., pressure of 0.1-0.105 MPa, and time of 12-15 min.

[0029] Preferably, in step (2), the external electric field is provided by an electric field generating device, which includes a constant voltage current source, an adjustable power output line and electrodes, and is used to form a small electric field in the alcoholamine solution. The small electric field promotes the migration and diffusion of carbamate generated by the reaction of the alcoholamine absorbent and carbon dioxide in the alcoholamine rich solution, increases the probability of collision between molecules, and achieves the effect of enhanced desorption.

[0030] More preferably, the electrode is a customized electrode, the cathode and the anode of the electrode are both platinum sheets, and the action of the constant voltage current source on the electrode forms an electric field in the rich solution.

[0031] Further preferably, the size of the platinum sheet is 15×15 mm-25×25 mm, and the purity is 99-99.99%.

[0032] Further preferably, the length of the electrode clamp of the electrode is 10-15 cm, which is suitable for a three-necked flask with a capacity of 250 mL and a diameter of 26 mm; at the same time, the electrode clamp is provided with a rubber stopper to adjust the area of ​​the electrode to penetrate into the rich liquid, which is suitable for the application of the electric field generating device in solutions of different volumes.

[0033] Preferably, the three-necked flask containing the rich solution is placed in an alcoholamine desorption device, and a small electric field is formed in the rich solution by the action of the constant voltage current source on the electrode. By controlling the voltage, the migration and diffusion of carbamate in the rich solution can be promoted, and the CO2 removal efficiency of alcoholamine can be further improved. More preferably, the alcoholamine desorption device includes an electric heating device and a condensation and drainage device; wherein the electric heating device is used for auxiliary disturbance and temperature measurement during the desorption process, and the condensation and drainage device is used for absorbing heat during the desorption process.

[0034] Preferably, in step (2), the desorption treatment is carried out in the alcoholamine desorption device.

[0035] Preferably, in step (2), the first preset temperature is the end temperature reached by preheating the electric heating device.

[0036] Preferably, the electric heating device is connected with a temperature probe, and the temperature probe is inserted into the rich liquid during the desorption process. In this preferred case, the desorption temperature can be measured more accurately, which is convenient for temperature control.

[0037] Preferably, the condensation drainage device uses a saturated sodium bicarbonate solution as the drainage liquid. In this preferred case, the desorbed product CO2 gas can be further prevented from being reabsorbed, and experimental errors can be avoided.

[0038] Preferably, in step (2), the conditions for the desorption treatment include: a pressure of 0.1-0.15 MPa and a time of 30-60 min.

[0039] Preferably, in step (2), the first preset temperature is 95-110°C, and the second preset temperature is 90-105°C.

[0040] According to a preferred specific implementation, step (2) also includes: before applying an external electric field to the rich liquid, combining the assembled electric field generating device and the alcohol amine desorption device into a system to ensure a sealed connection between the electric field generating device in the system and the various components in the alcohol amine desorption device.

[0041] Preferably, in step (2), the absorption load of the alcohol amine absorbent is 0.3-0.5 g CO2 / g alcohol amine absorbent.

[0042] Preferably, in step (2), the desorption load of the alcohol amine absorbent is 0.29-0.45 g CO2 / g alcohol amine absorbent.

[0043] The present invention will be described in detail below through examples.

[0044] In the following examples, unless otherwise specified, the raw materials and equipment used are commercially available.

[0045] N-methyldiethanolamine was purchased from Shanghai Titan Technology Co., Ltd. with a purity of 99%.

[0046] Triethylenetetramine was purchased from Shanghai Titan Technology Co., Ltd. with a purity of 99%.

[0047] p-Diazepam was purchased from Shanghai Titan Technology Co., Ltd. with a purity of 99%.

[0048] In the following examples, the relevant characteristic parameters are measured by the following methods:

[0049] (1) CO2 desorption rate: The volume of desorbed CO2 gas is collected by the water displacement method and Dalton's law of partial pressure. The water displacement volume is converted into the desorption mass of CO2 in combination with the density of CO2. The ratio of the desorption mass of CO2 to the absorption mass of CO2 is the desorption rate.

[0050] In the following examples, the electrode is a custom electrode, the cathode and anode of the electrode are both platinum sheets, the size of the platinum sheet is 20×20 mm, the purity is 99.99%, and the length of the electrode clip of the electrode is 12 cm.

[0051] In the following examples, the amount of alcohol amine absorbent used is 60g.

[0052] Example 1

[0053] (1) contacting and mixing an alcohol amine absorbent with CO2 to obtain a rich solution; placing a three-necked flask (capacity of 250 mL and diameter of 26 mm) containing the rich solution into an alcohol amine desorption device;

[0054] (2) preheating the electric heating device to a first preset temperature, combining the assembled electric field generating device (including a constant voltage current source, an adjustable power output line and an electrode) with the aforementioned alcohol amine desorption device (including the aforementioned rich liquid, the electric heating device and the condensation drainage device) into a system, and ensuring that the aforementioned electric field generating device in the system is sealed and connected with each component in the aforementioned alcohol amine desorption device;

[0055] Turning on the electric field generating device to apply an external electric field to the aforementioned rich liquid;

[0056] The alcohol amine desorption device is turned on, and the temperature probe connected to the electric heating device is inserted into the rich liquid, and a desorption process is performed at a second preset temperature;

[0057] The condensation drainage device is turned on, and a saturated sodium bicarbonate solution is used as the drainage liquid to obtain product CO2 gas and regenerated alcohol amine absorbent.

[0058] The method of using electric field to assist alcohol amine to desorb CO2 used in Examples 2 and 3 of the present invention is the same. The difference is that the alcohol amine absorbent and its ratio with CO2 are different, and the reaction conditions are different, see the list in Table 1. The unlisted parts are the same as in Example 1.

[0059] Table 1

[0060]

[0061] Note: Quality and dosage ratio 1 It is the mass dosage ratio of amine absorbent and CO2.

[0062] Example 4

[0063] The method of Example 1 is followed, except that the mass ratio of the alcohol amine absorbent to CO2 is different, that is, the mass ratio of the alcohol amine absorbent to CO2 is 1:0.57, and the rest are the same.

[0064] Example 5

[0065] The method of Example 1 is followed, except that the type of the alcohol amine absorbent is different, and the alcohol amine absorbent is a mixture of N-methyldiethanolamine and water in a mass ratio of 1:9, and the rest are the same.

[0066] Comparative Example 1

[0067] This comparative example adopts the same method as Example 1, except that the second preset temperature in this comparative example is the same as the first preset temperature, both of which are 105°C.

[0068] Comparative Example 2

[0069] This comparative example adopts the same method as Example 1, except that the reaction voltage of the external electric field in this comparative example is 10V.

[0070] Comparative Example 3

[0071] This comparative example adopts the same method as Example 1, except that no external electric field is applied in this comparative example.

[0072] Test Case

[0073] The property changes of the methods in each example at 10 minutes of desorption were recorded, and the absorption load and desorption load within 60 minutes were statistically analyzed to calculate the CO2 desorption rate. The results are shown in Table 2.

[0074] Table 2

[0075]

[0076] The present invention Figure 1 The graphs of the absorption results of the regenerated amine absorbent obtained in Example 1, Comparative Example 2 and Comparative Example 3 are provided as examples. Figure 1 It can be seen that the cyclic absorption load of the regenerated alcoholamine absorbent obtained in Comparative Examples 2 and 3 after 4 cycles is much smaller than that in Example 1; in particular, the absorption load of the regenerated alcoholamine absorbent obtained in Example 1 after 4 cycles is 0.22gCO2 / g alcoholamine absorbent, while the absorption load of the regenerated alcoholamine absorbent obtained in Comparative Example 2 after 4 cycles is reduced to 0.13gCO2 / g alcoholamine absorbent, which is 41wt% lower than that in Example 1.

[0077] The present invention Figure 2 The cyclic desorption result diagram of the regenerated ethanolamine absorbent obtained in Example 1, Comparative Example 2 and Comparative Example 3 is provided as an example; Figure 2 It can be seen that the cyclic desorption load of the regenerated amine absorbent obtained in Comparative Examples 2 and 3 after 4 cycles is also much smaller than that in Example 1.

[0078] This indicates that the regenerated alcohol amine absorbent obtained by the method for desorbing CO2 by alcohol amine using electric field as an aid provided by the present invention is not polluted or damaged, and has good recycling performance.

[0079] It can be seen from the above results that the method of using an electric field to assist alcohol amine in desorbing CO2 provided by the present invention can significantly improve the desorption effect of CO2, and the desorption rate is faster and more economical compared to the traditional heating method to promote alcohol amine decarbonization; in addition, the regenerated alcohol amine absorbent obtained after desorption also has good recyclability.

[0080] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for desorbing CO2 by using an electric field to assist alcohol amine, characterized in that: The method comprises the following steps: (1) contacting and mixing an alcohol amine absorbent with CO2 to obtain a rich liquid; (2) applying an external electric field to the rich liquid at a first preset temperature, and performing a desorption treatment at a second preset temperature to obtain a product CO2 gas and a regenerated alcohol amine absorbent; The second preset temperature is 2-5°C lower than the first preset temperature; and the reaction voltage of the external electric field is 3-6V.

2. The method according to claim 1, wherein: In step (1), the mass ratio of the alcohol amine absorbent to the CO2 is 1:0.4-0.

55.

3. The method according to claim 1, wherein: In step (1), the alcohol amine absorbent is a mixture of N-methyldiethanolamine and water in a mass ratio of 1:2-7.

4. The method according to any one of claims 1 to 3, wherein: In step (1), the alcohol amine absorbent is a mixture of triethylenetetramine and a polar solvent in a mass ratio of 1:2-6.

5. The method according to any one of claims 1 to 3, wherein: In step (1), the alcohol amine absorbent is a mixture of N-methyldiethanolamine and p-diazepine in a mass ratio of 4-7:

1.

6. The method according to any one of claims 1 to 3, wherein: In step (1), the contact mixing conditions include: temperature of 20-40° C., pressure of 0.1-0.105 MPa, and time of 12-15 min.

7. The method according to any one of claims 1 to 3, wherein: In step (2), the conditions of the desorption treatment include: pressure of 0.1-0.15 MPa, and time of 30-60 min.

8. The method according to any one of claims 1 to 3, wherein: In step (2), the first preset temperature is 95-110°C, and the second preset temperature is 90-105°C.

9. The method according to any one of claims 1 to 3, wherein: In step (2), the absorption load of the alcohol amine absorbent is 0.3-0.5 g CO2 / g alcohol amine absorbent.

10. The method according to any one of claims 1 to 3, wherein: In step (2), the desorption load of the alcohol amine absorbent is 0.29-0.45 g CO2 / g alcohol amine absorbent.

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