A solid-liquid phase change carbon dioxide absorbent with a controllable phase change time node and its application

Abstract

The present invention discloses a solid-liquid phase change carbon dioxide absorbent with a controllable phase change time node and its application. This non-aqueous solid-liquid phase change absorbent is composed of 2-(2-aminoethylamino)ethanol (AEEA), 2-amino-2-methyl-1-propanol (AMP), and N-methylpyrrolidone (NMP). Among them, AEEA is used as an activator to adjust the solid phase generation time, avoiding the precipitation of products at low CO2 loads, which may cause equipment blockage; AMP is used as the main absorbent reactant to ensure the high absorption capacity and regeneration performance of the absorbent; NMP with a high boiling point and low vapor pressure is used as a solvent to ensure the use stability of the absorbent. After absorbing CO2, this absorbent can undergo controllable solid-liquid phase separation, with CO2 enriched in the solid phase. Through two-phase separation, only the CO2 solid phase needs to be used for regeneration, thus effectively reducing the regeneration energy consumption. In summary, the high-efficiency non-aqueous solid-liquid phase change CO2 absorbent of this application has the characteristic of a controllable phase change time node, can reduce the risk of equipment blockage, and has broad application prospects.

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon dioxide emission reduction and recovery, and particularly relates to a solid-liquid phase change carbon dioxide absorbent with a controllable phase change time node and its application. Background Art

[0002] Global warming has become one of the important environmental problems faced by the world today. A large amount of anthropogenic carbon dioxide (CO 2 ) emissions are the main cause of global warming. Reducing CO 2 emissions is the only way to solve the problem of global warming. Fossil fuel combustion, especially coal combustion, is the main cause of excessive CO 2 emissions. At present, the energy structure of our country is still dominated by coal, and it is difficult to fundamentally change in the short term. Therefore, to achieve the "dual carbon" goal, the key lies in reducing CO 2 emissions in the energy system. The chemical absorption method based on ethanolamine (MEA) absorbent has the advantages of rapid CO 2 absorption and good selectivity, and has been widely studied in the field of CO 2 capture. However, the traditional MEA absorbent has a water content as high as 70%. During regeneration, a large amount of energy is consumed for heating and evaporation of water, resulting in a regeneration energy consumption of the absorbent as high as 3.2 - 4.0 GJ / ton CO 2 , and the high energy consumption limits the popularization and application of MEA absorbent. Therefore, it is urgent to develop an absorbent with high efficiency and low energy consumption.

[0003] In recent years, researchers have found that solid-liquid phase change absorbents have significant potential in reducing regeneration energy consumption. Before absorbing CO 2 , this type of absorbent is a homogeneous solution. After absorbing CO 2 , it will form a solid-liquid two-phase, and CO 2 is mainly enriched in the solid phase. Therefore, only by regenerating the solid phase can the regeneration volume of the absorbent be greatly reduced, thereby reducing the regeneration energy consumption. However, the existing solid-liquid phase change absorbents generally have the bottleneck problem of uncontrollable phase change time, that is, solid products are immediately generated after introducing CO 2 . The solid phase is generated at a very low CO 2 load, which is extremely likely to cause blockage of spraying equipment and pipelines. Therefore, if the solid-liquid phase change time node can be adjusted so that the absorbent approaches CO 2 saturation and is transported to the sedimentation tank to generate solid precipitation, problems such as blockage of spraying equipment and pipelines can be effectively avoided. Based on this idea, constructing a solid-liquid phase change absorbent with a controllable phase change time node is expected to provide new ideas for the research of high-efficiency and low-consumption carbon capture technology. Currently, there is no non-aqueous solid-liquid phase change CO 2 absorbent with a controllable phase change time node. Summary of the Invention

[0004] To achieve the above object, the present invention provides a non-aqueous solid-liquid phase change CO 2 absorbent, which has good CO 2 absorbing performance, low energy consumption, and the phase change time node can be flexibly regulated. The solid phase is convenient for separation, solving the problems that the solid phase precipitation of the existing solid-liquid phase change absorbent is uncontrollable and the product is likely to cause blockage of the spraying equipment and pipelines.

[0005] In this new non-aqueous solid-liquid phase change absorbent, hydroxyethyl ethylenediamine (AEEA) is used as an activator to regulate the generation time of the solid phase, avoiding the precipitation of the product under low CO 2 load and resulting in equipment blockage; 2-amino-2-methyl-1-propanol (AMP) is used as the main absorption reactant to ensure the high absorption capacity and regeneration performance of the absorbent; N-methylpyrrolidone (NMP) with a high boiling point and low vapor pressure is used as the solvent to ensure the use stability of the absorbent. Before absorbing CO 2 , the new absorbent is a homogeneous solution. Based on the regulation of AEEA, the absorbent can generate solid precipitation when approaching CO 2 saturation, while the existing solid-liquid phase change absorbent generates solids at extremely low CO 2 load. In contrast, the non-aqueous solid-liquid phase change absorbent of the present invention can flexibly regulate the phase change time node, so that the absorbent approaches CO 2 saturation and is transported to the sedimentation tank to generate solid precipitation, effectively avoiding problems such as blockage of the spraying equipment and pipelines.

[0006] One of the technical solutions adopted by the present invention to solve its technical problems is to provide a solid-liquid phase change carbon dioxide absorbent with a controllable phase change time node, which is composed of a phase change time node regulator, a main absorption reactant, and an organic solvent. Among them, the phase change time node regulator is hydroxyethyl ethylenediamine (AEEA), the main absorption reactant is 2-amino-2-methyl-1-propanol (AMP), and the organic solvent is N-methylpyrrolidone (NMP). The concentration of the regulator AEEA is 0.05 - 0.20 mol / L, and the concentration of the main absorption reactant AMP is 3 mol / L.

[0007] During the CO 2 absorption process using the AEEA-AMP-NMP non-aqueous solid-liquid phase change absorbent of the present invention, the principle of AEEA regulating the phase change time node is as follows: After AEEA absorbs CO 2 , an AEEA-carbamate product is generated. The AEEA-carbamate product combines with AMP-carbamate and protonated AMP through electrostatic attraction and van der Waals forces to form AEEAH + COO - / AMPCOO - and AEEAH+ COO - / AMPH + Ion pair. The newly formed ion pair has weaker hydrogen bonding than the original AMPCOO - / AMPH + ion pair, and has weaker hydrogen bonding at low load, so the product is not likely to aggregate and precipitate at low load; while at high load (close to saturation), the hydrogen bonding becomes stronger, so the product aggregates and precipitates from the solution. By regulating the phase change time node with AEEA, the AEEA-AMP-NMP non-aqueous solid-liquid phase change absorbent is saturated with CO 2 and transported to the sedimentation tank to produce solid products, which can effectively avoid problems such as blockage of spraying equipment and pipelines.

[0008] Furthermore, the non-aqueous solid-liquid phase change absorbent is a homogeneous solution before absorbing CO 2 and undergoes solid-liquid phase separation when it absorbs CO 2 to near saturation. The liquid phase is the CO 2 lean phase, and the solid phase is the CO 2 rich phase.

[0009] Furthermore, in the two phases formed after the non-aqueous solid-liquid phase change absorbent absorbs CO 2 to saturation, the mass of the CO 2 rich phase accounts for 30-40% of the total mass of the absorbent, and its CO 2 content accounts for 90-95% of the total absorption amount.

[0010] Furthermore, the non-aqueous solid-liquid phase change absorbent is used to absorb pure CO 2 or CO with a volume fraction of 5-20% in the mixed gas 2 . When the absorption temperature is 30-60 °C, the absorption capacity is 1.2-1.9 mol CO 2 / (kg absorbent).

[0011] Furthermore, after the non-aqueous solid-liquid phase change absorbent absorbs CO 2 , the obtained CO 2 rich phase can be regenerated by microwave heating.

[0012] Even further, the process conditions for regeneration are: microwave heating power 100-400 W, regeneration time 5 min, regeneration efficiency 69%-85%, and the desorbed high-purity CO 2 can be used subsequently.

[0013] Another object of the present invention is to provide the application of the above-mentioned non-aqueous solid-liquid phase change absorbent for CO 2 capture in the field of CO 2 capture.

[0014] Furthermore, it includes the following steps:

[0015] (1) Using AMP as the main absorption reactant, AEEA as the phase change time node regulator, and NMP as the organic solvent, prepare a non-aqueous solid-liquid phase change absorbent by dissolving AEEA and AMP in NMP according to the concentration of AEEA being 0.05 - 0.20 mol / L and the concentration of AMP being 3 mol / L.

[0016] (2) Absorb pure CO 2 or CO with a volume fraction of 5 - 20% in the mixed gas 2 using the non-aqueous solid-liquid phase change absorbent in step (1), with an absorption temperature of 30 - 60 °C, an absorption load of 1.2 - 1.9 mol CO 2 / (kg absorbent). After the absorbent absorbs CO 2 , solid-liquid phase separation occurs. The liquid phase is the CO 2 lean phase, and the solid phase is the CO 2 rich phase.

[0017] (3) Separate the two phases of the CO 2 rich phase and the CO 2 lean phase in (2), and regenerate the CO 2 rich phase by microwave heating desorption. The microwave heating power is 100 - 400 W, and the regeneration time is 5 min to obtain the regenerated absorbent and the trapped CO 2 .

[0018] After using the above absorbent to absorb CO 2 , the absorbent undergoes solid-liquid phase change and is divided into two phases: the CO 2 rich phase and the CO 2 lean phase. Just separate the CO 2 rich phase for heating regeneration, which can greatly reduce the regeneration amount of the absorbent and thus reduce the regeneration energy consumption. After the regenerated CO 2 rich phase is mixed with the CO 2 lean phase, it can be reused for CO 2 absorption.

[0019] The beneficial effects of the present invention are:

[0020] The present invention uses hydroxyethyl ethylenediamine (AEEA) as the phase change time node regulator, 2-amino-2-methyl-1-propanol (AMP) as the main absorption reactant, and N-methylpyrrolidone (NMP) with a high boiling point and low vapor pressure as the solvent to form a non-aqueous solid-liquid phase change absorbent. When this absorbent absorbs CO 2 , solid-liquid phase separation occurs when it is close to saturation. The CO 2It is mainly enriched in the solid phase. During the regeneration stage, only the solid phase needs to be regenerated, reducing the regeneration volume to lower the regeneration energy consumption. This new absorbent is a homogeneous solution before absorbing CO 2 Based on the regulation of AEEA, the absorbent can produce solid precipitation when it is close to CO 2 saturation, while the existing solid-liquid phase change absorbents produce solids at extremely low CO 2 loads. In contrast, the non-aqueous solid-liquid phase change absorbent of the present invention can flexibly control the phase change time node, enabling the absorbent to produce solid precipitation when it is close to CO 2 saturation and is transported to the sedimentation tank, effectively avoiding problems such as blockage of spraying equipment and pipelines. Therefore, the non-aqueous solid-liquid phase change absorbent of the present invention will be an economical and energy-saving CO 2 absorbent with practical application prospects, which is more conducive to industrial promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0022] Figure 1 It is the precipitation time graph of the absorbents of Example 1 and Comparative Example 1 of the present invention after absorbing CO 2

[0023] Figure 2 It is the load and CO 2 absorption load when the solid precipitation of the non-aqueous solid-liquid phase change absorbent of Example 1 of the present invention occurs

[0024] Figure 3 It is the distribution of CO 2 after saturation in the two phases when the non-aqueous solid-liquid phase change absorbent of Example 1 of the present invention absorbs CO 2

[0025] Figure 4 It is the absorption load of the non-aqueous solid-liquid phase change absorbent of Example 1 of the present invention at different absorption temperatures

[0026] Figure 5 It is the regeneration efficiency of the non-aqueous solid-liquid phase change absorbent of Example 1 of the present invention at different regeneration powers DETAILED DESCRIPTION OF THE INVENTION

[0027] ​​Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0028] Example 1

[0029] A non-aqueous solid-liquid phase change absorbent for CO 2 capture is prepared by using N-methylpyrrolidone (NMP) as a solvent according to the concentration of hydroxyethyl ethylenediamine (AEEA) being 0.05 - 0.2 mol / L and the concentration of 2-amino-2-methyl-1-propanol (AMP) being 3 mol / L to form an AEEA-AMP-NMP absorbent, which is the non-aqueous solid-liquid phase change absorbent. This absorbent is used to absorb CO with a volume ratio of 5 - 20% in the mixed gas 2 , and the absorption temperature is 30 - 60 °C.

[0030] After the absorbent is saturated, solid-liquid phase change occurs. The solid-liquid two phases are separated, and the solid phase is regenerated by microwave heating. The regeneration power is 100 - 400 W, and the regeneration time is 5 min.

[0031] Comparative Example 1

[0032] AMP is dissolved in NMP to prepare an AMP-NMP solution with an AMP concentration of 1.0 mol / L, and the rest are the same as in Example 1.

[0033] Experimental Example 1: Phase separation effect, absorption capacity, and detection of CO content in the solid-liquid two phases after the non-aqueous solid-liquid phase change absorbent of Example 1 absorbs CO 2 2 content detection

[0034] At 40 °C, the precipitation generation situation during the absorption of CO by the non-aqueous solid-liquid phase change absorbent AEEA-AMP-NMP of Example 1 and the absorbent AMP-NMP of Comparative Example 1 was investigated, and the CO absorption load of AEEA-AMP-NMP and the CO content in the two phases were detected simultaneously. 2 2 2 content.

[0035] Method: Prepare 25 mL of the corresponding absorbents according to Example 1 and Comparative Example 1, and transfer the absorbents into different bubbling reactors. Place the absorption tube in a water bath at 40 °C, and introduce a mixed gas containing CO into the absorbent 2 ​​​The gas starts the absorption performance test until absorption saturation. After absorption saturation, by standing still, the phase separation of the absorbent can be observed. During the absorption process, the outlet flow rate is measured using a soap film flowmeter, and CO 2 The absorption rate can be calculated from the difference between the inlet flow rate and the outlet flow rate, and CO 2 The absorption load can be obtained by integrating the absorption rate with respect to the absorption time. The saturated absorbent is separated into solid-liquid two phases by vacuum filtration, and the CO in the liquid phase is determined by the sulfuric acid hydrolysis method. 2 content, and the CO in the solid phase 2 content can be calculated from the difference between the total CO 2 capacity and the CO 2 capacity in the liquid phase.

[0036] Results: As Figure 1 shown, at AEEA concentrations of 0.05 - 0.2 M, both AEEA-AMP-NMP can delay the generation time of solid precipitation to varying degrees, and as the AEEA concentration increases, the precipitation generation time is gradually postponed. While for the AMP-NMP in Comparative Example 1, precipitation occurs immediately after 5 min of CO 2 absorption.

[0037] Figure 2 shows the CO 2 absorption capacity and precipitation generation of the AEEA-AMP-NMP absorbent at different AEEA concentrations. It can be seen that during the absorption process, the precipitation generation time is gradually postponed as the AEEA concentration increases, achieving the purpose of generating precipitation when approaching absorption saturation. At the same time, the CO 2 absorption capacity of the absorbent also slightly increases as the AEEA concentration increases.

[0038] Figure 3 shows the CO 2 content in the solid and liquid phases of the AEEA-AMP-NMP absorbent after CO 2 absorption at different AEEA concentrations. It can be seen that the change in AEEA concentration has a slight effect on the CO 2 content in the solid and liquid phases of AEEA-AMP-NMP. After CO 2 is absorbed, it is mainly enriched in the solid phase, and the CO 2 content in the solid phase accounts for more than 90% of the total absorption.

[0039] Figure 4 shows the CO 2 absorption capacity of the AEEA-AMP-NMP absorbent at different absorption temperatures. It can be seen that the absorption capacity decreases as the absorption temperature increases, but it can still maintain a good absorption capacity at 60 °C, showing good temperature adaptability.

[0040] The AEEA-AMP-NMP non-aqueous solid-liquid phase change absorbent of the present invention undergoes solid-liquid phase separation after absorbing CO 2 and CO 2 is enriched in the solid phase. Compared with traditional organic amine solutions, only the solid phase needs to be used for regeneration, which reduces the regeneration volume and will greatly reduce the regeneration energy consumption. In addition, based on the regulation of AEEA, the AEEA-AMP-NMP non-aqueous solid-liquid phase change absorbent produces precipitation when it is close to saturation after absorbing CO 2 , which can effectively avoid problems such as blockage of spraying equipment and pipelines.

[0041] Experimental Example 2: Regeneration performance of the non-aqueous solid-liquid phase change absorbent of Example 1

[0042] Since CO 2 is mainly enriched in the solid phase after the solid-liquid phase change absorbent absorbs, only the solid phase needs to be regenerated in the regeneration process, which can effectively reduce the energy consumption of the carbon capture process. Currently, the main regeneration methods of absorbents include thermal desorption, microwave desorption, pressure swing method, etc. In this experimental example, the microwave desorption method is used, and the regeneration efficiency of the absorbent is measured to investigate the regeneration ability of the absorbent.

[0043] Method: Take the non-aqueous solid-liquid phase change absorbent AEEA-AMP-NMP of Example 1, absorb CO 2 in the mixed gas to saturation at 40 °C, perform solid-liquid separation by vacuum filtration, and microwave-desorb the solid phase at different powers (100 - 400 W) for 5 minutes. Measure the CO 2 regeneration efficiency of the absorbent at different desorption powers to investigate the regeneration performance of the absorbent.

[0044] Result: As Figure 4 shown, the CO 2 rich phase of the AEEA-AMP-NMP absorbent can achieve good CO 2 desorption at 100 - 400 W. The CO 2 regeneration efficiency increases with the increase of the regeneration power, and the regeneration efficiency can remain above 69% at different regeneration powers, and is as high as 84.6% at a power of 390 W. It shows that the non-aqueous solid-liquid phase change absorbent of Example 1 has good regeneration performance.

[0045] The above is only a preferred embodiment of the present invention, and thus the scope of implementation of the present invention cannot be limited thereby. That is, equivalent changes and modifications made according to the scope of the present invention patent and the content of the specification should still fall within the scope covered by the present invention.

Claims

1. A non-aqueous solid-liquid phase change absorbent for carbon dioxide (CO 2 ) capture It is characterized in that it is composed of hydroxyethyl ethylenediamine (AEEA), 2-amino-2-methyl-1-propanol (AMP) and organic solvent N-methylpyrrolidone (NMP); for the absorbent, the concentration of AEEA is 0.05 - 0.20 mol / L and the concentration of AMP is 3 mol / L; The absorbent can regulate the phase change time node by changing the concentration of AEEA, so that the solid-liquid phase change occurs near the absorption saturation; after the solid-liquid phase separation, the liquid phase is CO 2 lean phase, and the solid phase is CO 2 rich phase; the 2 mass of the CO rich phase accounts for 30-40% of the total mass of the absorbent, and its CO 2 content accounts for 90-95% of the total absorption amount.

2. A non-aqueous solid-liquid phase change absorbent for CO 2 capture according to claim 1 It is characterized in that The absorbent is used to absorb pure CO 2 or CO with a volume fraction of 5-20% in the mixed gas 2 , and the absorption temperature is 30-60 o °C. The absorption capacity is 1.2-1.9 mol CO 2 / (kg absorbent).

3. The non-aqueous solid-liquid phase change absorbent for CO 2 capture as claimed in claim 1, It is characterized in that The absorbent absorbs CO 2 The solid phase obtained after that is regenerated by microwave heating.

4. A non-aqueous solid-liquid phase change absorbent for CO 2 capture It is characterized in that the regeneration process conditions are: microwave heating power 100 - 400 W, regeneration time 5 min, and regeneration efficiency 69% - 85%.

5. Use of a non-aqueous solid-liquid phase change absorbent according to any one of claims 1 to 4 for CO 2 capture in the field of CO 2 capture applications.

6. The application according to claim 5, It is characterized in that it comprises the following steps: (1) Using AMP as the main absorption reaction agent, AEEA as the phase change time node regulator, and NMP as the organic solvent, dissolve AEEA and AMP in NMP to prepare a non-aqueous solid-liquid phase change absorbent according to the concentration of AEEA being 0.05 - 0.20 mol / L and the concentration of AMP being 3 mol / L. (2) Absorb pure CO with the non-aqueous solid-liquid phase change absorbent in step (1). 2 or CO with a volume fraction of 5-20% in the mixed gas 2 , the absorption temperature is 30-60 o °C, the absorption load is 1.2-1.9 mol CO 2 / (kg absorbent), after the absorbent absorbs CO 2 , solid-liquid phase separation occurs, the liquid phase is the CO 2 lean phase, and the solid phase is the CO 2 rich phase; (3) Separate the CO-rich phase and the CO-lean phase in step (2), and use microwave heating desorption to regenerate the CO-rich phase. The microwave heating power is 100 - 400 W, and the regeneration time is 5 min to obtain the regenerated absorbent and the trapped CO. 2 rich phase and CO 2 lean phase separation, and use microwave heating desorption to regenerate the CO 2 rich phase. The microwave heating power is 100 - 400 W, and the regeneration time is 5 min to obtain the regenerated absorbent and the trapped CO 2 .

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