Amino-functional ionic complex anhydrous absorbent for absorbing carbon dioxide and preparation method thereof

Abstract

The present application relates to the technical field of carbon dioxide recovery, and particularly relates to an amino-functional ion complex anhydrous absorbent for absorbing carbon dioxide and a preparation method thereof, which solves the problems of low carbon dioxide absorption rate, high desorption energy consumption and corrosion to equipment of the existing ammonia water solution method and alcohol amine solution method, and provides an ionic liquid, i.e. carbamate monohydroxyethane-dimethyl sulfoxide ([DETAH][HCOO]-MEA-DMSO) ionic solution, a manufacturing method of the ionic liquid, which comprises the steps of preparing diethylenetriaminocarbamate [DETAH][HCOO], preparing diethylenetriaminocarbamate-ethanolamine [DETAH][HCOO]-MEA solution and preparing amino-functional ion complex anhydrous absorbent [DETAH][HCOO]-MEA-DMSO, the amino-functional ion complex anhydrous absorbent prepared by the method has the advantages of high absorption rate, large absorption amount, regeneration, low desorption energy consumption, corrosion resistance to metal and the like. Meanwhile, the process is simple, easy to realize, can effectively control the corrosion to the equipment, save the cost, and can recycle and utilize the carbon dioxide as a resource.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of carbon dioxide recovery, in particular to an amino-functional ion complex anhydrous absorbent for absorbing carbon dioxide and a preparation method thereof. BACKGROUND

[0002] The massive emission of CO2 is the main cause of global warming. The hydrogen-rich carbon cycle blast furnace process is an important technology for realizing low-carbon metallurgy in the future, and the recycling of CO and H2 in blast furnace gas can be realized through CO2 capture technology of blast furnace gas, thereby improving energy utilization efficiency and reducing carbon emissions of blast furnace ironmaking. The commonly used CO2 capture methods in industry are ammonia water solution method and alcohol amine solution method, etc. Although these methods have the advantages of mature technology and low cost, they also have obvious disadvantages: high energy consumption for desorption, easy corrosion of equipment and poor recycling performance. As a kind of green and efficient CO2 absorbent, functional ionic liquid has become a research hotspot in the field of chemical absorption method for capturing CO2.

[0003] In the chemical absorption method of carbon capture technology, the performance of the chemical absorbent determines the CO2 capture effect and the level of system energy consumption. In traditional chemical absorption, hot potassium base solution, ammonia water and alcohol amine solution are commonly used as absorbents in the carbon capture process, which has good effect on capturing CO2 and mature technology. However, due to the high energy consumption of chemical absorption, the poor oxidation resistance of absorbent, the easy degradation and deterioration, and the strong corrosion, etc. For example, Chinese invention patent CN201310339924.X discloses an organic amine composite absorbent for removing carbon dioxide in coal-fired flue gas, Chinese invention patent CN201410852514.X discloses an ionic solution for absorbing carbon dioxide gas in flue gas and a manufacturing method thereof, and Chinese invention patent CN201811626843.7 discloses a preparation method of a new type of low-water CO2 absorption ternary complex organic amine agent. The absorbent in such patents adds deionized water, which is a water solution, and has corrosion to pipelines and equipment during long-term use. Chinese invention patent CN202010993465.7 discloses a non-aqueous liquid-liquid phase change absorbent for carbon dioxide capture and its application. Chinese invention patent CN201810928071.6 discloses a non-aqueous carbon dioxide absorbent and a method for absorbing and desorbing carbon dioxide. Although there is no water in the method, the corrosion is reduced, and it belongs to alcohol amine type non-aqueous solution, but the desorption energy consumption is high, and it is easy to volatilize and degrade.

[0004] In view of the above defects, the present inventors have finally obtained the present application after long-term research and practice. SUMMARY

[0005] The present application aims to solve how to reduce the existing flue gas CO2 emissions, solve the problem of easy corrosion of equipment with water-containing absorbent and easy oxidation and volatile degradation of anhydrous alcohol amine, and provide an amino-functional ion complex anhydrous absorbent for absorbing carbon dioxide and a preparation method thereof.

[0006] In order to achieve the above-mentioned purpose, the present application discloses an amino-functional ion complex anhydrous absorbent for absorbing carbon dioxide, which is [DETAH][HCOO]-MEA-DMSO amino-functional ion complex anhydrous absorbent, comprising the following components by mass fraction: diethylene triamine 3% to 10%, formic acid 2% to 5%, ethanol amine solution 5% to 15%, and dimethyl sulfoxide 40 to 80%.

[0007] The diethylene triamine is analytical pure, the formic acid is analytical pure, the ethanol amine solution is analytical pure, and the dimethyl sulfoxide is analytical pure.

[0008] The present application also discloses a preparation method of the amino-functional ion complex anhydrous absorbent for absorbing carbon dioxide, comprising the following steps: under the condition of a temperature of 20 to 60 DEG C and normal pressure, diethylene triaminomethane carbonate is used as an activator to be compounded with an organic solvent ethanol amine (MEA) to obtain a modified organic amine absorbent.

[0009] The mass ratio of the diethylene triaminomethane carbonate to the organic solvent ethanol amine is 1:1 to 1:4.

[0010] The preparation method of the diethylene triaminomethane carbonate comprises the following steps: weighing diethylene triamine (DETA) and formic acid (HCOOH) for standby, diluting the diethylene triamine solution in an ice water bath by adding deionized water, adding formic acid drop by drop while stirring in the ice water bath, continuing to stir for more than 12 hours after the formic acid is completely added, then distilling the mixed solution in a 70 DEG C water bath for 1 to 3 hours, and then drying at 60 DEG C for 48 hours to obtain diethylene triaminomethane carbonate.

[0011] The molar ratio of the diethylene triamine to the formic acid is 1:1.2.

[0012] Compared with the prior art, the amino-functional ion complex anhydrous absorbent for absorbing carbon dioxide in the present application can absorb low content carbon dioxide (15% to 22%) in blast furnace gas, has the advantages of high carbon capture amount, low desorption energy consumption, non-volatility, non-oxidative degradation, strong metal pipeline corrosion resistance, and the like, and is a "green" chemical solvent with good thermal stability and chemical stability. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 Effects of different temperatures on the absorption capacity of the anhydrous system mixed absorbent;

[0014] Figure 2 Effect of different temperatures on the absorption rate of the anhydrous system mixed absorbent;

[0015] Figure 3 Effect of different concentrations on the absorption capacity of the anhydrous system mixed absorbent;

[0016] Figure 4 Effect of different concentrations on the absorption rate of the anhydrous system mixed absorbent;

[0017] Figure 5 Effect of different desorption temperatures on the desorption performance of the anhydrous system absorbent;

[0018] Figure 6 Cycling performance of the anhydrous system mixed absorbent;

[0019] Figure 7 The experimental photos of the carbon dioxide absorbent prepared by the present application before and after corroding 20# carbon steel sheets, a1-a3 are MEA-H2O, [DETAH][HCOO]-MEA-H2O, [DETAH][HCOO]-MEA-DMSO before corrosion, and b1-b3 are MEA-H2O, [DETAH][HCOO]-MEA-H2O, [DETAH][HCOO]-MEA-DMSO after corrosion, respectively;

[0020] Figure 8 The SEM photos of the surface of 20# steel sheets amplified by 1000 times, (a) MEA-H2O, (b) [DETAH][HCOO]-MEA-H2O, (c) [DETAH][HCOO]-MEA-DMSO, (d) uncorroded;

[0021] Figure 9 Effect of different solvents on the CO2 absorption capacity;

[0022] Figure 10 Effect of different solvents on the CO2 absorption rate;

[0023] Figure 11 Effect of different solvents on the desorption load;

[0024] Figure 12 Effect of different solvents on the energy consumption of CO2 desorption. DETAILED DESCRIPTION

[0025] The above and other technical features and advantages of the present application will be made more apparent by the following detailed description of the application, given in conjunction with the accompanying drawings.

[0026] Example 1

[0027] 1. First, add an appropriate amount of deionized water to dilute the diethylenetriamine solution in an ice-water bath, then add formic acid. After the formic acid is added, continue stirring with a magnetic stirrer for at least 12 hours. Then, use a rotary evaporator to distill the mixed solution in a 70°C water bath for 1 to 3 hours, then place it in a 60°C vacuum oven and dry for 48 hours to obtain diethylenetriamine formate.

[0028] 2. At an absorption temperature of 20°C to 60°C, a gas-liquid ratio of 2:1, and normal pressure, diethylenetriamine [DETAH][HCOO] is used as an activator and compounded with an organic solvent ethanolamine in a mass ratio of 1:1 to obtain a modified organic amine absorbent diethylenetriamine-ethanolamine;

[0029] 3. Then, the diethylenetriamine formate-ethanolamine [DETAH][HCOO]-MEA is dissolved in DMSO solvent to form an anhydrous ionic solution, wherein the mass percentage of [DETAH][HCOO]-MEA in the ionic solution is 20%.

[0030] like Figure 1 、 Figure 2 As shown, the absorbent temperature is 20 ° C and the CO2 absorption capacity is 0.98 mol·mol -1 , the maximum CO2 absorption rate is 0.00790mol·(mol·min) -1 The absorbent temperature is 30℃ and the CO2 absorption capacity is 0.85mol·mol -1 The maximum CO2 absorption rate is 0.00796 mol·(mol·min) -1 The absorbent temperature is 40℃ and the CO2 absorption capacity is 0.75mol·mol -1 The maximum CO2 absorption rate is 0.00797 mol·(mol·min) -1 The absorbent temperature is 50℃ and the CO2 absorption capacity is 0.73mol·mol -1 , the maximum CO2 absorption rate is 0.008mol·(mol·min) -1 When the temperature rises to 60℃, the CO2 absorption capacity of [DETAH][HCOO]-MEA-DMSO anhydrous absorbent is 0.71mol·mol -1 , CO2 maximum absorption rate 0.00808mol·(mol·min) -1 The absorption capacity decreased significantly, which shows that the CO2 absorption capacity of the anhydrous absorbent decreases with increasing temperature, and the maximum absorption rate increases slightly with increasing absorbent temperature. In general, it has little effect on the absorption rate. When the absorbent temperature is 20℃, the CO2 absorption capacity is the largest.

[0031] Example 2

[0032] 1. First, add a proper amount of deionized water to dilute the diethylene triamine solution in an ice water bath, then add formic acid. After the addition of formic acid, continue stirring with a magnetic stirrer for more than 12 hours. Distill the mixed solution in a 70°C water bath for 1-3 hours using a rotary evaporator, then place it in a 60°C vacuum incubator for 48 hours to obtain diethylene triamine formate;

[0033] 2. At a temperature of 20°C, a gas-liquid ratio of 2:1, and normal pressure, diethylene triamine formate [DETAH][HCOO] is used as an activator to prepare a modified organic amine absorbent diethylene triamine formate-ethanol amine by compounding with organic solvent ethanol amine at a mass ratio of 1:1. Then the diethylene triamine formate-ethanol amine [DETAH][HCOO]-MEA is dissolved in DMSO solvent to form an amino functional ion complex anhydrous absorbent.

[0034] As shown in Figure 3 , Figure 4 , the total mass fraction of [DETAH][HCOO]-MEA is in the range of 20-60%, when the mass fraction is 20%, the CO2 absorption capacity of the anhydrous absorbent mixed absorbent is 0.98 mol·mol -1 ; when the mass fraction is 30%, the CO2 absorption capacity of the anhydrous absorbent mixed absorbent is 0.85 mol·mol -1 ; when the mass fraction is 40%, the CO2 absorption capacity of the anhydrous absorbent mixed absorbent is 0.74 mol·mol -1 ; when the mass fraction is 50%, the CO2 absorption capacity of the anhydrous absorbent mixed absorbent is 0.64 mol·mol -1 ; when the mass fraction rises to 60%, the CO2 absorption capacity of the [DETAH][HCOO]-MEA-DMSO anhydrous absorbent decreases to 0.58 mol·mol -1 ; when the mass fraction is 20%, the CO2 absorption capacity of the anhydrous absorbent mixed absorbent is the largest.

[0035] Example 3

[0036] The CO2-saturated mixed absorbent is placed in a reaction bottle, the oil bath is opened, the desorption temperature and stirring speed are controlled, and the cooling circulating water pump is opened; when bubbles begin to appear in the absorbent, the power consumption is recorded by an intelligent electric meter, and the desorbed gas is measured by a CO2 flow meter after cooling. The CO2 desorption load and CO2 desorption rate are calculated.

[0037] The desorption experiment was carried out on the saturated solution of the anhydrous absorbent with the mass ratio of MEA to [DETAH][HCOO] being 1:1 and the total mass fraction of [DETAH][HCOO] and MEA being 20%. As shown in Figure 5 , the desorption temperature range was 90-120°C. When the desorption temperature of the anhydrous absorbent was 90°C, the desorption rate was the lowest, being 40.02%. With the increase of the desorption temperature, the desorption rate gradually increased. When the desorption temperature was 100°C and 110°C, the desorption rates were 51.81% and 62.85%, respectively. When the desorption temperature increased to 120°C, the desorption efficiency of the anhydrous absorbent reached the maximum value, being 68.78%. At this time, the desorption rate of the anhydrous absorbent increased by 71.86% compared with that at 90°C. The desorption rate was the best at the desorption temperature of 120°C.

[0038] Example 4

[0039] The CO2-saturated mixed absorbent was placed in a reaction bottle, and the oil bath was opened to control the desorption temperature and stirring speed, and the cooling circulating water pump was opened. When bubbles began to appear in the absorbent, the power consumption was recorded by an intelligent electric meter, and the desorbed gas was measured by a CO2 flowmeter after cooling. The CO2 desorption load and CO2 desorption rate were calculated.

[0040] At the desorption temperature of 120°C, the absorption-desorption cycle test was carried out on the [DETAH][HCOO]-MEA-DMSO anhydrous absorbent for 5 times, as shown in Figure 6 , the test results showed that the CO2 saturation absorption amount of the [DETAH][HCOO]-MEA-DMSO anhydrous absorbent gradually decreased with the increase of the cycle regeneration times. The first absorption of the [DETAH][HCOO]-MEA-DMSO anhydrous absorbent was the best, and the absorption amount reached 0.98 mol·mol -1 . After 5 times of cycle regeneration, the absorption amounts of the [DETAH][COO]-MEA-H2O system mixed absorbent decreased to 0.65 mol·mol -1 , 0.63 mol·mol -1 , 0.62 mol·mol -1 and 0.62 mol·mol -1 , respectively. The absorbent had good recyclability and good application prospect in industry.

[0041] Example 5

[0042] A 20# carbon steel sheet was immersed in fresh and saturated solutions of [DETAH][HCOO]-MEA-H2O and [DETAH][HCOO]-MEA-DMSO (the ratio of [DETAH][HCOO] to MEA was 1:1, the mass fraction of the mixed absorbent was 20%, and the corrosion temperature was 30°C). After being allowed to corrode naturally for 168 hours, the corrosion rate was measured. Fresh and saturated aqueous solutions of 20% mass fraction of ethanolamine were used as control experiments. Then, a 20# carbon steel sheet was used as the working electrode, and fresh and saturated [DETAH][HCOO]-MEA-H2O and [DETAH][HCOO]-MEA-DMSO solutions were used as electrolytes (the ratio of [DETAH][HCOO] to MEA was 1:1, and the mass fraction of the mixed absorbent was 20%). The electrolyte temperature was controlled at 30°C, and the Tafel polarization curve and electrochemical impedance spectrum were measured. Fresh and saturated aqueous solutions of ethanolamine with a concentration of 20% by mass were also used as control experiments to measure their corrosiveness to the 20# carbon steel sheet.

[0043] The corrosion rates of the solutions obtained from the experiment are shown in Table 1:

[0044] Table 1 Corrosion rate of 20# carbon steel sheet in different absorbents (mm·a -1 )

[0045]

[0046] like Figure 7 、 8 As shown in the figure, after the 20# carbon steel sheet was corroded by the saturated MEA-H2O and [DETAH][HCOO]-MEA-H2O absorbents, obvious etching stripes appeared on the steel sheet surface. However, after the steel sheet was corroded by the anhydrous [DETAH][HCOO]-MEA-DMSO system, only cutting lines caused by sandpaper polishing were observed on the surface of the steel sheet. Therefore, the saturated [DETAH][HCOO]-MEA-DMSO anhydrous system is much less corrosive to 20# carbon steel sheet than the saturated [DETAH][HCOO]-MEA-H2O and MEA-H2O solutions.

[0047] Example 6

[0048] At a temperature of 20°C, a ratio of [DETAH][HCOO] to MEA of 1:1, and a concentration of 20 wt%, the effect of different organic solvents replacing water on the CO2 absorption capacity of the mixed absorbent was investigated. Figure 9 It can be seen that after absorption saturation, the capacities of [DETAH][HCOO]-MEA-BP and [DETAH][HCOO]-MEA-PEG200 are 0.71 mol·mol -1、 0.57mol·mol -1 , which is smaller than the absorption capacity of [DETAH][HCOO]-MEA-H2O (0.85 mol·mol -1 ), while the CO2 absorption capacity of the anhydrous [DETAH][HCOO]-MEA-DMSO system is 0.98 mol·mol -1 Compared with the [DETAH][HCOO]- MEA-H2O system, the CO2 absorption capacity is increased by about 15.29%. It can be seen that the anhydrous system absorbent prepared by using DMEA instead of water has a higher CO2 absorption capacity than the water system absorbent.

[0049] At a temperature of 20°C, a ratio of [DETAH][HCOO] to MEA of 1:1, and a concentration of 20 wt%, the effect of different organic solvents replacing water on the CO2 absorption rate of the mixed absorbent was investigated. Figure 10 It can be seen that the maximum CO2 absorption rates of [DETAH][HCOO]-MEA-BP and [DETAH][HCOO]-MEA-PEG200 are 0.00751 mol·(mol·min) respectively. -1 、0.00739mol·(mol·min) -1 , which is lower than the maximum CO2 absorption rate of [DETAH][HCOO]-MEA-H2O (0.00798 mol·(mol·min) -1 ), while the maximum CO2 absorption rate of the anhydrous [DETAH][HCOO]-MEA-DMSO system is 0.00808 mol·(mol·min) -1 Compared with the [DETAH][HCOO]-MEA-H2O system, the maximum CO2 absorption rate is slightly improved, and the high CO2 absorption rate is maintained within the first 100 minutes. This shows that the anhydrous system absorbent prepared by using DMEA instead of water has a better CO2 absorption rate than the aqueous system absorbent.

[0050] At a desorption temperature of 120°C, desorption experiments were conducted on four saturated [DETAH][HCOO]-MEA mixed absorbents to explore the effects of different organic solvents on the desorption load of the mixed absorbents. Figure 11 It shows that the desorption load of the mixed absorbent of [DETAH][HCOO]-MEA-DMSO anhydrous system is 0.67 mol·mol after desorption. -1 , the desorption load of the absorbent of the [DETAH][HCOO]-MEA-BP anhydrous system is 0.50 mol·mol -1and the desorption load of [DETAH][HCOO]-MEA-H2O is 0.50 mol·mol -1 The desorption load of [DETAH][HCOO]-MEA-BP anhydrous system absorbent is 0.39 mol·mol -1 Therefore, the desorption load of [DETAH][HCOO]-MEA-DMSO anhydrous system mixed absorbent is the largest, which is 34% higher than that of the water system mixed absorbent, and thus the anhydrous system absorbent formed by replacing water with DMSO has better desorption performance.

[0051] At a desorption temperature of 120℃, the desorption experiments of the four saturated [DETAH][HCOO]-MEA mixed absorbents were carried out to explore the influence of different organic solvents on the desorption energy consumption of the mixed absorbent. In this section, the electric meter was used to measure the desorption energy consumption, although the measured result is not the absolute value of the CO2 desorption energy consumption, which includes the heat dissipation amount in the desorption process and the additional power consumption amount of the heating equipment during operation, so that the measured value is higher than the actual value, but this section only explores the influence of the anhydrous absorbent formed by replacing water with an organic solvent on the desorption energy consumption, and only the relative value of the CO2 desorption energy consumption of different anhydrous absorbents under the same experimental conditions is needed, therefore, it is feasible to calculate the desorption energy consumption by recording the power consumption amount by the electric meter. It can be known from Figure 12 The desorption energy consumption of the anhydrous system mixed absorbent is lower than that of the water system mixed absorbent, and the desorption energy consumption of the [DETAH][HCOO]-MEA-DMSO anhydrous system mixed absorbent is the lowest, which is 3.10 MJ·Kg -1 The desorption energy consumption of the [DETAH][HCOO]-MEA-DMSO anhydrous system mixed absorbent is only 45.59% of that of the water system mixed absorbent. This is because the boiling point of water is 373K, and a large amount of latent heat of vaporization is consumed during long-time desorption, while the boiling points of DMSO, BP and PEG200 are much higher than that of water, and the latent heat of vaporization required during desorption is small, and the specific heat capacity of the organic solvent is much smaller than that of water, so the sensible heat of the anhydrous system mixed absorbent during heating to the desorption temperature is greatly reduced

[99] Therefore, the anhydrous system absorbent formed by replacing water with DMSO has lower desorption energy consumption.

[0052] The above only describes the preferred embodiments of the present application, which are only illustrative but not limiting. Those skilled in the art understand that many changes, modifications and even equivalents can be made to the present application within the spirit and scope defined by the claims of the present application, but all will fall within the protection scope of the present application.

Claims

1. An amino functional ion composite anhydrous absorbent for absorbing carbon dioxide, characterized in that: The amino functional ion composite anhydrous absorbent is [DETAH][HCOO]-MEA-DMSO amino functional ion composite anhydrous absorbent, which includes the following components by mass fraction: 3% to 10% diethylenetriamine, 2% to 5% formic acid, 5% to 15% ethanolamine solution, and 40% to 80% dimethyl sulfoxide.

2. The amino functional ion composite anhydrous absorbent for absorbing carbon dioxide according to claim 1, characterized in that: The diethylenetriamine was of analytical grade, the formic acid was of analytical grade, the ethanolamine solution was of analytical grade, and the dimethyl sulfoxide was of analytical grade.

3. A method for preparing the amino functional ion composite anhydrous absorbent for absorbing carbon dioxide according to claim 1 or 2, characterized in that: The following steps are involved: At a temperature of 20-60°C and normal pressure, diethylenetriamine as an activator is compounded with an organic solvent, ethanolamine, to prepare a modified organic amine absorbent.

4. The method for preparing the amino-functional ion composite anhydrous absorbent for absorbing carbon dioxide according to claim 3, wherein: The mass ratio of the diethylenetriamine salt to the organic solvent ethanolamine is 1:1 to 1:

4.

5. The method for preparing the amino functional ion composite anhydrous absorbent for absorbing carbon dioxide according to claim 3, wherein: The preparation method of diethylenetriamine formate comprises the following steps: weighing diethylenetriamine and formic acid for standby use, adding deionized water to dilute the diethylenetriamine solution in an ice-water bath, adding formic acid dropwise while stirring in the ice-water bath, continuing stirring for more than 12 hours after the formic acid is added, then distilling the mixed solution in a 70°C water bath for 1 hour to 3 hours, and then drying at 60°C for 48 hours to obtain diethylenetriamine formate.

6. The method for preparing the amino functional ion composite anhydrous absorbent for absorbing carbon dioxide according to claim 5, characterized in that: The molar ratio of diethylenetriamine to formic acid is 1:1.2.

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