Amino-functionalized ionic liquid-alcohol amine compound absorbent for CO2 capture and preparation method of amino-functionalized ionic liquid-alcohol amine compound absorbent

Abstract

The invention discloses an amino-functionalized ionic liquid-alcohol amine compound absorbent for CO2 capture and a preparation method thereof, the compound absorbent is prepared from a main absorbent alcohol amine, an absorption promoter amino-functionalized ionic liquid and water, the mass concentration of the main absorbent in the compound absorbent is 15-26%, the mass concentration of the absorption promoter in the compound absorbent is 15-26%, and the mass concentration of the absorption promoter in the compound absorbent is 15-26%. The mass ratio of the main absorbent to the absorption enhancer is (1-5): 1. The preparation method comprises the following steps: respectively weighing the main absorbent alkylol amine and the absorption enhancer amino-functionalized ionic liquid according to the ratio, putting the main absorbent alkylol amine and the absorption enhancer amino-functionalized ionic liquid into a container, adding water into the container, uniformly stirring, sealing the container, and carrying out ultrasonic dispersion treatment for 4-6 minutes to obtain the compound absorbent. The preparation method is simple, and the prepared compound absorbent has good carbon capture capability and stability, is compatible with a carbon capture device in industrial operation at present, and has a wide industrial application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon dioxide capture, and in particular to an amino-functionalized ionic liquid-alcoholamine composite absorbent for CO2 capture and a preparation method thereof. Background Art

[0002] Carbon capture, utilization and storage (CCUS) technology plays a vital role in global climate change mitigation and effective control of carbon dioxide (CO2) emissions. This technical path aims to capture CO2 from large flue gas emission sources (such as coal-fired power plants, cement plants, etc.) and prevent it from entering the atmosphere through utilization or long-term storage, thereby significantly reducing greenhouse gas accumulation. However, the practical application of CCUS technology still faces many challenges, especially in the key link - CO2 capture stage, the development of efficient and economically viable absorbents is particularly urgent.

[0003] At present, although alcohol amine absorbents such as MEA (monoethanolamine) and DEA (diethanolamine) have been widely used in commercial-scale CO2 capture devices, they also have obvious limitations. Although alcohol amines have a high affinity for CO2, they have poor stability and are prone to degradation under actual use conditions, resulting in a decrease in absorption effect. As a green solvent, ionic liquids (ILs) are considered by researchers to be a very potential low-energy capture solvent for CO2 due to their adjustable structure and properties, extremely low vapor pressure and low specific heat, but ionic liquids have encountered several bottlenecks in practical applications. The first problem is its high cost. Compared with traditional absorbents, the synthetic raw materials and cumbersome synthesis process of ionic liquids make their market price much higher than similar products, which undoubtedly increases the overall economic burden of CCUS projects; secondly, ionic liquids generally have a high viscosity, especially at high concentrations, which not only affects their mass transfer efficiency in the absorption tower, but also may cause difficulties in pipeline transportation, bringing significant technical difficulties to large-scale industrial applications. Therefore, the development of new CO2 absorbents with high efficiency capture performance, good stability and low cost has become the key to CCUS technology research. Summary of the invention

[0004] The purpose of the present invention is to provide an amino-functionalized ionic liquid-alcoholamine composite absorbent for CO2 capture and a preparation method thereof. The preparation method is simple, and the prepared composite absorbent has good carbon capture capacity and stability, and is compatible with the currently industrially operated carbon capture devices, and has broad industrial application prospects.

[0005] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention is:

[0006] An amino-functionalized ionic liquid-alcoholamine composite absorbent for CO2 capture is prepared from a main absorbent alcoholamine, an absorption promoter amino-functionalized ionic liquid and water. The mass concentration of the main absorbent in the composite absorbent is 15-26%, and the mass ratio between the main absorbent and the absorption promoter is (1-5):1.

[0007] Preferably, the alcoholamine is hydroxyethylethylenediamine.

[0008] Preferably, the absorption enhancer is diethylenetriamine imidazole or diethylenetriamine piperazine.

[0009] Preferably, the mass concentration of the main absorbent in the composite absorbent is 21%, the mass ratio between the main absorbent and the absorption enhancer is 2:1; and the total concentration of the composite absorbent is 31%.

[0010] The present invention also provides a method for preparing the above-mentioned amino-functionalized ionic liquid-alcoholamine composite absorbent for CO2 capture, which comprises weighing the main absorbent alcoholamine and the absorption promoter amino-functionalized ionic liquid in a proportion and placing them in a container, adding water to the container, stirring evenly, and then sealing the container and performing ultrasonic dispersion treatment for 4-6 minutes to obtain the composite absorbent.

[0011] Compared with the prior art, the present invention has the following beneficial effects:

[0012] (1) The alcohol amine-ionic liquid composite absorbent prepared by the present invention has stronger absorption and desorption capabilities than the traditional MEA absorbent, and its CO2 absorption capacity is as high as 0.50g CO2 / g amine to 0.55g CO2 / g amine, the desorption amount is 0.42g CO2 / g amine to 0.44g CO2 / g amine, and the rich liquid desorption rate can reach up to 88%, which has excellent CO2 absorption and desorption performance;

[0013] (2) The alcohol amine-ionic liquid composite absorbent prepared by the present invention has a viscosity of 3.7 mPa·s to 4.7 mPa·s at 30°C, which is much lower than the ionic liquid CO2 absorbent currently used in the field of carbon capture. In addition, the system is compatible with the composite amine absorption system device that is currently the most widely used in industry, and there is no need to make large-scale changes to the existing device, which has broad industrial application value;

[0014] (3) After five cycles of absorption-desorption, the regeneration rate of the alcoholamine-ionic liquid composite absorbent prepared by the present invention is still maintained at more than 90%, and the performance of the absorbent does not change significantly, and has good stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A diagram of the CO2 absorption device used in this embodiment;

[0016] Figure 2 A diagram of the CO2 desorption device used in this embodiment;

[0017] Figure 3 Schematic diagram of the effect of the composite absorbents prepared in two blank control groups and Examples 1-3 on the CO2 absorption;

[0018] Figure 4 Schematic diagram of the effect of the composite absorbents prepared in two blank control groups and Examples 1-3 on the CO2 desorption amount;

[0019] Figure 5 Schematic diagram of the effect of the composite absorbents prepared by two blank control groups and Examples 4-6 on the CO2 absorption;

[0020] Figure 6 Schematic diagram of the effect of the composite absorbents prepared in two blank control groups and Examples 4-6 on the CO2 desorption amount;

[0021] Figure 7 This is a schematic diagram of the change in absorption capacity of the composite absorbent prepared in Example 5 after five cycles;

[0022] Figure 8 This is a schematic diagram of the change in desorption amount of the composite absorbent prepared in Example 5 after five cycles;

[0023] Fig. 9 This is a schematic diagram of the color change of the composite absorbent prepared in Example 5 after five cycles of absorption-desorption. DETAILED DESCRIPTION

[0024] The present invention is further described in detail below in conjunction with specific embodiments.

[0025] Example 1

[0026] An amino-functionalized ionic liquid-alcoholamine composite absorbent for CO2 capture is prepared from a main absorbent hydroxyethylethylenediamine (AEEA), an absorption promoter diethylenetriamineimidazole ([DETA][Im]) and water, wherein the mass ratio between the main absorbent and the absorption promoter is 5:1.

[0027] The preparation method is as follows: 7.5g AEEA and 1.5g [DETA] [Im] are weighed and placed in a container according to a ratio, 20g deionized water is added to the container, and the mixture is stirred evenly with a glass rod. After the beaker is sealed, the mixture is placed in an ultrasonic device for dispersion treatment for 5 minutes, and finally an AEEA-[DETA] [Im] composite absorbent is formed with a total concentration of 31%, a total mass of 29g, and a mass ratio of AEEA and [DETA] [Im] of 5:1. The viscosity of the composite absorbent at 30°C is measured to be 3.7mPa·s.

[0028] The preparation process of [DETA][Im] is as follows:

[0029] (1) Weigh 0.05 mol of diethylenetriamine and 0.05 mol of imidazole into a round-bottom flask, add 10 mL of a mixed solution of water and 40 mL of ethanol to dissolve them, and react with magnetic stirring at 25° C. and 500 rpm for 24 h;

[0030] (2) After the reaction is completed, the mixed solution is distilled under reduced pressure at 70° C. for at least 3 h to constant weight to remove unreacted raw materials and excess solvent in the ionic liquid. The obtained solution is then dried in a vacuum drying oven for 12 h to finally obtain a novel amino-functionalized ionic liquid [DETA][Im].

[0031] Example 2

[0032] The difference between this embodiment and embodiment 1 is that: 6g AEEA and 3g [DETA] [Im] are weighed, and the other steps are kept consistent with embodiment 1 to form an AEEA-[DETA] [Im] composite absorbent with a mass ratio of AEEA to [DETA] [Im] of 2:1; the viscosity is measured to be 3.9 mPa·s at 30°C.

[0033] Example 3

[0034] The difference between this embodiment and embodiment 1 is that: 4.5 g AEEA and 4.5 g [DETA] [Im] are weighed, and the other steps are kept consistent with embodiment 1 to form an AEEA-[DETA] [Im] composite absorbent with a mass ratio of AEEA to [DETA] [Im] of 1:1; the viscosity is measured to be 4.5 mPa·s at 30°C.

[0035] Example 4

[0036] An amino-functionalized ionic liquid-alcoholamine composite absorbent for CO2 capture is prepared from a main absorbent hydroxyethylethylenediamine (AEEA), an absorption promoter diethylenetriaminepiperazine ([DETA][Pz]) and water, wherein the mass ratio between the main absorbent and the absorption promoter is 5:1.

[0037] The preparation method is as follows: 7.5g AEEA and 1.5g [DETA] [Pz] are weighed and placed in a container according to a ratio, 20g deionized water is added to the container, and the mixture is stirred evenly with a glass rod. After the beaker is sealed, the mixture is placed in an ultrasonic device for dispersion treatment for 5 minutes, and finally an AEEA-[DETA] [Pz] composite absorbent is formed with a total concentration of 31%, a total mass of 29g, and a mass ratio of AEEA and [DETA] [Pz] of 5:1. The viscosity of the composite absorbent at 30°C is measured to be 4.3mPa·s.

[0038] The preparation process of [DETA][Pz] is as follows:

[0039] (1) Weigh 0.05 mol of diethylenetriamine and 0.05 mol of piperazine into a round-bottom flask, add 10 mL of a mixed solution of water and 40 mL of ethanol to dissolve them, and react with magnetic stirring at 40° C. and 500 rpm for 24 h;

[0040] (2) After the reaction is completed, the mixed solution is distilled under reduced pressure at 70° C. for at least 3 h to constant weight to remove unreacted raw materials and excess solvent in the ionic liquid. The obtained solution is then dried in a vacuum drying oven for 12 h to finally obtain a novel amino-functionalized ionic liquid [DETA][PZ].

[0041] Example 5

[0042] The difference between this embodiment and embodiment 1 is that: 6g AEEA and 3g [DETA] [PZ] are weighed, and the other steps are kept consistent with embodiment 1 to form an AEEA-[DETA] [PZ] composite absorbent with a mass ratio of AEEA to [DETA] [PZ] of 2:1; after measurement, the viscosity at 30°C is 4.4mPa·s.

[0043] Example 6

[0044] The difference between this embodiment and embodiment 4 is that: 4.5 g AEEA and 4.5 g [DETA] [PZ] are weighed, and the other steps are kept consistent with embodiment 1 to form an AEEA-[DETA] [PZ] composite absorbent with a mass ratio of AEEA to [DETA] [PZ] of 1:1; the viscosity is measured to be 4.7 mPa·s at 30°C.

[0045] Tests prove:

[0046] Put 30g of the prepared composite absorbent into the bubbling absorption tube, and place the bubbling absorption tube in a constant temperature oil bath at 40℃; after the temperature of the composite absorbent stabilizes, open the valve of the CO2 gas cylinder, adjust the pressure reducing valve to control the inlet pressure at 0.1MPa, and control the inlet volume at 100ml / min through the mass flow meter. Use a wet flow meter to detect the amount of CO2 in the outlet gas of the bubbling absorption tube in real time, and record the data every 2 minutes. When the difference between the inlet and outlet flow rates is less than 5mL / min, it is considered that the absorption has reached saturation and the test is stopped. The specific absorption device is as follows Figure 1 shown.

[0047] During the desorption process, the bubbling absorption tube containing the saturated ionic liquid solution-organic amine composite solution is placed in a constant temperature oil bath at 130°C, connected to a serpentine condenser, and regenerated by normal pressure heating. The amount of CO2 desorbed from the solution is read by a wet flow meter. The data is recorded every 2 minutes, and the experiment is stopped when the wet flow meter stops rotating. The specific regeneration experimental device is as above. Figure 2 shown.

[0048] At the same time, two blank control groups were set up, namely, 30g MEA aqueous solution with a mass fraction of 30% and 30g AEEA aqueous solution with a mass fraction of 30%.

[0049] Each AEEA-ILs composite absorbent prepared in the above embodiments was tested according to the above determination method, and the obtained CO2 absorption-desorption performance data was plotted into a curve as follows: Figure 3-5 The analysis shows that the saturated absorption capacity of the AEEA-[DETA][Im] system is between 0.45g CO2 / g amine and 0.48g CO2 / g amine, and the desorption capacity is between 0.36g CO2 / g amine and 0.40g CO2 / g amine, among which the 20% AEEA-10% [DETA][Im] composite absorbent has the best comprehensive absorption and desorption performance, with an absorption capacity of 0.45g CO2 / g amine, a desorption capacity of 0.40g CO2 / g amine, and a desorption rate of 88.89%. The saturated absorption capacity of the AEEA-[DETA][PZ] system is between 0.50g CO2 / g amine and 0.55g CO2 / g amine, and the desorption capacity is between 0.42g CO2 / g amine and 0.44g CO2 / g amine. Among them, the 20% AEEA-10% [DETA][PZ] composite absorbent has the best comprehensive absorption and desorption performance, with an absorption capacity of 0.50g CO2 / g amine, a desorption capacity of 0.44g CO2 / g amine, and a desorption rate of 88%.

[0050] Among them, the 20% AEEA-10% [DETA] [PZ] composite absorbent has the best absorption and desorption performance. The composite absorbent was repeated five times according to the above absorption-desorption test steps. The changes in the absorption and desorption amounts of the five times are as follows Figure 7-8 As shown, the solution color changes as follows Fig. 9 As shown in the figure, the absorption and desorption amount of the 20% AEEA-10% [DETA] [PZ] composite absorbent remained basically constant after five cycles, and the solution color did not change significantly, indicating that the system has good stability and has broad industrial application prospects.

Claims

1. An amino-functionalized ionic liquid-alcoholamine composite absorbent for CO2 capture, characterized in that: The composite absorbent is prepared from alcohol amine as a main absorbent, amino functionalized ionic liquid as an absorption promoter and water. The mass concentration of the main absorbent in the composite absorbent is 15-26%, and the mass ratio between the main absorbent and the absorption promoter is (1-5):

1.

2. The amino-functionalized ionic liquid-alcoholamine composite absorbent for CO2 capture according to claim 1, characterized in that: The alcoholamine is hydroxyethylethylenediamine.

3. An amino-functionalized ionic liquid-alcoholamine composite absorbent for CO2 capture according to claim 1 or 2, characterized in that: The absorption enhancer is diethylenetriamine imidazole or diethylenetriamine piperazine.

4. An amino-functionalized ionic liquid-alcoholamine composite absorbent for CO2 capture according to claim 1 or 2, characterized in that: The mass concentration of the main absorbent in the composite absorbent is 21%, the mass ratio between the main absorbent and the absorption promoter is 2:1; and the total concentration of the composite absorbent is 31%.

5. A method for preparing an amino-functionalized ionic liquid-alcoholamine composite absorbent for CO2 capture as claimed in any one of claims 1 to 4, characterized in that: The main absorbent alcohol amine and the absorption promoter amino-functionalized ionic liquid are weighed in a proportion and placed in a container, water is added to the container, stirred evenly, and then the container is sealed and subjected to ultrasonic dispersion treatment for 4-6 minutes to obtain a composite absorbent.

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