Anhydrous homogeneous carbon dioxide amine absorbent based on aeea-amp-dmso

Abstract

The application belongs to the technical field of carbon dioxide absorbent, discloses anhydrous homogeneous carbon dioxide composite amine absorbent based on AEEA-AMP-DMSO, and the absorbent is composed of the following substances: hydroxyethyl ethylenediamine, isobutanol amine, dimethyl sulfoxide. The scheme has excellent comprehensive performance, the absorption load is 1.0739 mol / mol, the maximum absorption rate is 0.035 mol / (mol.min), and the absorption can be maintained for about 20 min; the desorption load is 1.04312 mol / mol, the maximum desorption rate is 0.0867 mol / (mol.min); the regeneration efficiency can still reach more than 91% after 6 cycles; the corrosion is 0.0765 mm / a; and the regeneration energy consumption is 2.287 GJ / t CO2.

Description

Technical Field

[0001] This invention belongs to the field of carbon dioxide absorbent technology, specifically relating to an anhydrous homogeneous carbon dioxide composite amine absorbent based on AEEA-AMP-DMSO. Background Technology

[0003] Among existing CO2 emission reduction technologies, CO2 capture, utilization, and storage (CCUS) is one of the key technologies for achieving carbon neutrality. Current CO2 capture technologies include chemical absorption, physical adsorption, and membrane separation, among which chemical absorption is a relatively mature technology, and organic amine absorption is already used in limited industrial applications.

[0004] Currently, organic amine solution absorbents used in industry suffer from drawbacks such as low absorption load, high regeneration energy consumption, and high corrosivity. Taking 30% MEA as an example, its absorption load is 0.557 mol / mol, its regeneration energy consumption is 3.99 GJ / tCO2, and its corrosivity is 0.1644 mm / a.

[0005] Based on this, a new type of carbon dioxide absorbent with superior performance was designed and developed. Summary of the Invention

[0006] To overcome the above-mentioned technical problems, the present invention provides an anhydrous homogeneous carbon dioxide composite amine absorbent based on AEEA-AMP-DMSO.

[0007] The present invention adopts the following technical solution:

[0008] The anhydrous homogeneous carbon dioxide composite amine absorbent based on AEEA-AMP-DMSO is composed of the following substances: hydroxyethyl ethylenediamine, isobutanolamine, and dimethyl sulfoxide.

[0009] Preferably, the mass fractions of hydroxyethyl ethylenediamine, isobutanolamine, and dimethyl sulfoxide in the absorbent are 16%, 2.5%, and 81.5%, respectively.

[0010] Preferably, the absorption load of the absorbent is above 1.

[0011] Preferably, the regeneration efficiency of the absorbent is above 97%.

[0012] Preferably, the absorption temperature of the absorbent is 40°C.

[0013] Preferably, the desorption temperature of the absorbent is 90°C.

[0014] Compared with the prior art, the beneficial effects of the present invention are:

[0015] In this scheme, AEEA has two amino groups, which can effectively improve the absorption capacity and absorption rate of the absorbent. DMSO, as a solvent, reduces the corrosivity of the absorbent and ensures that the products of AEEA / AMP exist stably in the solvent as carbamates. Carbamates are extremely unstable and can be desorbed at relatively low temperatures, thus improving the desorption load and regeneration efficiency of the absorbent. At the same time, the addition of the sterically hindered amine AMP, with a large functional group attached to its amino nitrogen atom, produces a steric hindrance effect. The resulting carbamate structure is unstable (it can be regenerated at 70-90℃) and weakens the interaction between products within the absorbent, improving the regeneration efficiency of the solution. Furthermore, the addition of AMP can effectively improve the absorbent's resistance to degradation.

[0016] This scheme exhibits excellent overall performance, with an absorption load of 1.0739 mol / mol and a maximum absorption rate of 0.035 mol / (mol·min), which can be maintained for approximately 20 minutes; a desorption load of 1.04312 mol / mol and a maximum desorption rate of 0.0867 mol / (mol·min); a regeneration efficiency of over 91% after 6 cycles; a corrosivity of 0.0765 mm / a; and a regeneration energy consumption of 2.287 GJ / t CO2. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the concentration screening absorption experiment results;

[0018] Figure 2 This is a physical image of the concentration screening experiment results;

[0019] Figure 3 This is a schematic diagram of the experimental results of CO2 absorption performance of the composite amine absorbent;

[0020] Figure 4 This is a schematic diagram showing the experimental results of CO2 absorption performance of 30% MEA absorbent;

[0021] Figure 5 This is a schematic diagram showing the experimental results of the desorption performance of the composite amine absorbent at different temperatures;

[0022] Figure 6 This is a schematic diagram showing the experimental results of the CO2 desorption performance of the composite amine absorbent;

[0023] Figure 7 This is a schematic diagram showing the experimental results of CO2 desorption performance of 30% MEA absorbent;

[0024] Figure 8 This is a schematic diagram of the experimental results of the cycle performance of the composite amine absorbent;

[0025] Figure 9 This is a schematic diagram of the results of a corrosion comparison experiment. Detailed Implementation

[0026] The embodiments of the present invention are described in detail below. Unless otherwise specified, the raw materials and equipment used can be purchased from the market or are commonly used in the art. The methods in the embodiments, unless otherwise specified, are conventional methods in the art. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0027] Anhydrous homogeneous carbon dioxide composite amine absorbent based on AEEA-AMP-DMSO

[0028] plan

[0029] Hydroxyethyl ethylenediamine (AEEA, C p,AEEA =104.15 g / mol, ρ AEEA =1.03g / mL) is an organic base compound. The molecule contains both active amino and hydroxyl groups, has strong polarity, and is a multi-level amine with two amino groups. It is used as an absorption promoter to ensure a high CO2 absorption rate and absorption load.

[0030] Isobutanolamine (AMP, C p,AMP =89.14 g / mol, ρ AMP =0.934 g / mL) is a sterically hindered amine. A large functional group is attached to the amino nitrogen atom of this type of amine, which produces a sterically hindered amine effect. Due to the influence of the steric hindrance effect, the resulting carbamate structure is unstable and easily decomposes. The addition of AMP brings the characteristics of reduced viscosity, reduced regeneration energy consumption, anti-degradation properties, and improved regeneration rate to the system.

[0031] Dimethyl sulfoxide (DMSO, C) p,DMSO =78.13 g / mol, ρ DMSO =1.10g / mL), it has the characteristics of high stability, low heat capacity and low vaporization enthalpy. As an organic diluent, it can reduce sensible heat and heat of vaporization, and effectively reduce the energy consumption of absorbent regeneration.

[0032] The three components are mixed evenly to prepare a carbon dioxide composite amine absorbent.

[0033] To preliminarily screen absorbents that maintain homogeneity before and after CO2 absorption and have low solution viscosity, 40℃ was used as the absorption temperature, and viscosity was measured using a digital viscometer NDJ-1S. The volume of the absorbent was 50 mL.

[0034] According to Table 1 and Figure 1 , 2The results showed that the absorption load of the absorbent gradually decreased with the addition of AMP, and the viscosity of the rich solution became excessive with the increase of organic amine concentration. Therefore, to optimize the regeneration performance while ensuring a sufficiently high absorption load, sample No. 2 was mainly selected for further experiments.

[0035]

[0036] The following experiments will test the performance of this absorbent.

[0037] In the experiment, the CO2 absorption (or desorption) rate is defined as the amount of CO2 absorbed (or desorbed) per mole of amine per unit time. It can be obtained by the difference between the inlet and outlet gas flow rates, and the calculation formula is as follows:

[0038]

[0039] In the formula, r represents the CO2 absorption (or desorption) rate (mol·mol⁻¹). -1 ·min -1 Q in and Q out P represents the inlet and outlet flow rates (mL / min) of the absorption bottle, respectively; act P0 and T represent the atmospheric pressure (kPa) under actual and standard conditions, respectively; act T0 and T0 represent the actual and standard temperatures (K), respectively; n amine represents the molar mass (mol) of the amine in the absorbent. During the desorption process, only the outlet flow rate is measured; the inlet flow rate Q is assumed to be used when calculating the desorption rate. in It is 0.

[0040] The CO2 absorption (or desorption) load is defined as the amount of CO2 absorbed (or desorbed) per mole of amine. It can be calculated by integrating the absorption rate over the absorption (or desorption) time, and the formula is as follows:

[0041]

[0042] In the formula, L is the CO2 absorption (or desorption) load, mol / mol; t is the absorption (or desorption) time, min.

[0043] Regeneration efficiency is defined as the ratio of CO2 desorption load to the CO2 absorption load of fresh absorbent, and the calculation formula is as follows:

[0044] η=L d / L a ×100%

[0045] In the formula, η is the regeneration efficiency, %; L aCO2 absorption load for the first absorption by the absorbent, mol / mol; L d CO2 desorption load, mol / mol. Cyclic performance was obtained by analyzing the CO2 load and efficiency after 6 cycles of the selected absorbent.

[0046] In practical industrial applications, it is also necessary to measure the regeneration energy consumption. Low-energy-consumption absorbents can achieve lower operating costs and losses. Regeneration energy consumption includes the sensible heat of absorbent regeneration (Q). sen ), the heat of desorption reaction of CO2 products (Q) rxn ) and the latent heat (Q) carried away by the regenerated gas. latent In this experiment, the heat of reaction was determined using a C80 micro calorimeter, and its specific heat capacity C was determined using DSC. p The energy consumption for absorbent regeneration consists of three parts: heat of reaction, sensible heat, and latent heat, calculated using the following formula:

[0047] Q regen =Q rxn +Q sens +Q latent

[0048]

[0049] In the formula, Q regen Energy consumption for absorbent regeneration, GJ / t CO2; Q rxn Q sens Q latent These represent the heat of reaction, sensible heat, and latent heat of the absorbent, respectively, in GJ / t CO2. rxn enthalpy of CO2 absorption reaction of the absorbent, kJ / mol; M is the molar mass of CO2, 44 g / mol; m is the mass of CO2-rich solution, kg; C p ΔT is the specific heat capacity of the CO2-rich solution, kJ / (kg·K); ΔT is the temperature difference between the solution after heating by the heat exchanger and the temperature of the stripping tower (temperature difference between the absorbent entering and exiting the desorption unit), K, generally taken as 10K; The mass of CO2 produced during the desorption process is expressed in g; m DMSO The mass of the solvent evaporated during desorption, in kg; generally, amines do not evaporate. The heat of vaporization of the evaporated solvent is kJ / kg, approximately equal to 677 kJ / kg (189℃, 52.9 kJ / mol).

[0050] I. Absorption Comparison Experiment

[0051] Experimental equipment: N2 gas cylinder, CO2 gas cylinder, D07 series mass flow meter, absorption bottle, water bath, flue gas analyzer.

[0052] Experimental conditions: absorption temperature 40℃, absorption time 70min, atmospheric pressure.

[0053] Control: 30% MEA absorbent.

[0054] Experimental method: Pass a mixture of N2 and CO2 gases through an absorption bottle containing an absorbent, record the amounts of N2 and CO2 before and after the process, and calculate the absorption performance.

[0055] The test results are as follows Figure 3 , Figure 4 As shown:

[0056] The absorption load of MEA at an absorption time of 70 min is only 0.557 mol / mol, with a maximum absorption rate of 0.0132 mol / (mol·min). At an absorption time of 30 min, the absorption load is 0.439 mol / mol, representing 78.74% of the total absorption load, and its maximum desorption rate is 0.0213 mol / (mol·min). The maximum absorption rate of this absorbent is 0.035 mol / (mol·min), which can be maintained for approximately 20 min, with an absorption load of 1.0739 mol / mol.

[0057] II. Desorption performance experiments of this absorbent at different temperatures

[0058] Experimental equipment: N2 gas cylinder, D07 series mass flow meter, absorption bottle, water bath, flue gas analyzer.

[0059] Experimental conditions: desorption time 90 min, atmospheric pressure.

[0060] Experimental method: N2 was passed through an absorption bottle containing this absorbent at temperatures of 70°, 75°, 80°, 85°, and 90° respectively. The amounts of N2 and CO2 before and after the absorption were recorded, and the desorption performance was calculated.

[0061] The test results are as follows Figure 5 As shown.

[0062] III. Desorption Comparison Experiment

[0063] Experimental equipment: N2 gas cylinder, D07 series mass flow meter, absorption bottle, water bath, flue gas analyzer.

[0064] Control: 30% MEA absorbent.

[0065] Experimental conditions: desorption temperature 90℃, desorption time 90min; desorption temperature 90℃, desorption time 90min, atmospheric pressure.

[0066] Experimental method: N2 was passed through absorption bottles containing absorbent, and the amounts of N2 and CO2 before and after the process were recorded to calculate the desorption performance.

[0067] Experimental results are as follows Figure 6 , Figure 7 As shown.

[0068] The maximum regeneration rate of this reagent is 0.0867 mol / (mol·min), and the desorption load is 1.04312 mol / mol.

[0069] IV. Regeneration Efficiency and Cyclic Performance Experiment

[0070] The absorption-desorption process of this reagent was repeated, and the experimental results are as follows: Figure 8 As shown, the regeneration efficiency of fresh reagent is 97.06%, and the regeneration efficiency can still reach more than 91% after 6 cycles.

[0071] V. Calculation of Regenerative Energy Consumption

[0072] The specific heat capacity of the absorbent was measured by DSC at the Analysis and Testing Center of Chongqing University, Cp = 2.39 J·g⁻¹·℃⁻¹; the heat of reaction was obtained by C80 micro calorimeter at the Qingshan Lake Energy Research Base of Zhejiang University, heat of reaction = 84.972 kJ / mol; the solvent loss during the cyclic desorption process was 0.3019 g.

[0073]

[0074] V. Corrosion Test

[0075] When using chemical absorbents to capture CO2, the solutions are generally highly corrosive, causing corrosion to the absorption equipment and other components. Selecting a suitable absorbent and evaluating its corrosive effect on equipment materials during CO2 capture is crucial for corrosion control, reducing operating costs, and ensuring the safe operation of the CO2 capture plant. This experiment uses the "weight loss method" to determine its corrosivity.

[0076] 20# steel sheets (40mm×13mm×2mm) were progressively polished with sandpaper of different grits, then washed sequentially with pure water, ethanol, and acetone, and dried with cold air before being weighed. The steel sheets were then immersed in a corrosive medium, and sample vials were placed in a 40℃ constant temperature water bath for 28 days. After the initial soaking, the sheets were washed sequentially with 8% HNO3 (volume ratio) solution, 5% NaOH (mass ratio) solution, pure water, and acetone, and then dried and weighed. The calculation formula for corrosion performance studies is as follows:

[0077]

[0078] In the formula, CR is the corrosion rate, mm / y; Δm is the weight loss of the sample, g; and ρ is the density of #20 steel, g / cm³. 3 The usual value is 7.85 g / cm³. 3 A is the surface area of ​​the sample, in cm². 2 t is the cycle of the corrosion experiment, h.

[0079] The corrosion performance of this scheme was measured to be 0.0765 mm / a using the "weight loss method".

[0080] The results of the comparative experiment on the corrosivity of this reagent and 30% MEA are as follows: Figure 9 As shown.

[0081] Reaction mechanism analysis

[0082] The reaction mechanism between amine absorbents and CO2 is currently mainly explained by the zwitterionic mechanism, and the reaction equation is as follows:

[0083]

[0084] The overall reaction formula is:

[0085]

[0086] In the formula, R1R2NH is a primary or secondary amine; R1R2NH + COO ― It is an amphoteric ion; It is a protonated amine; R1R2NCOO ― It is a carbamate (salt).

[0087] For 30% MEA containing water, and the absorption products also containing bicarbonate / carbonate, the reaction mechanism is as follows:

[0088]

[0089] According to the reaction formula, when the product is carbamate, the maximum CO2 absorption capacity of the absorbent is 0.5 mol CO2·molamine. -1 When the product is bicarbonate / carbonate, the maximum CO2 absorption capacity of the absorbent is 1 mol CO2·mol amine. -1 .

[0090] However, the reaction mechanism for CO2 absorption by the reagents AEEA / AMP / DMSO has certain unique characteristics. Both AEEA and AMP react with CO2 to form unstable zwitterions, some of which have intermediates that tautomerize into carbamates. In this case, the maximum CO2 absorption capacity of the absorbent is 1 mol CO2·mol amine. -1Carbamic acids are unstable and easily decompose, but can be stabilized by polar organic solvents. This scheme uses DMSO, a polar protophilic organic solvent. For carbamic acids, they can interact with DMSO through hydrogen bonds, allowing them to remain stable in solution. However, AEEA / AMP exhibits different degrees of bias in forming carbamic acids in DMSO (AEEA is more likely to form carbamic acids). Therefore, adding AMP will reduce the absorption load of the absorbent. However, correspondingly, with the addition of the sterically hindered amine AMP, the large functional group attached to the amino nitrogen atom creates a steric hindrance effect, resulting in an unstable carbamate structure (which can be regenerated at 70-90℃) and weakening the interactions between products within the absorbent, thus improving the regeneration efficiency of the solution.

[0091] Regarding the products, in addition to the AMPH obtained from the aforementioned analysis... + AMPCOO - AMP-COOH. Another amine, AEEA, is quite special, containing two amino groups, one primary and one secondary, both of which can react. This is because in the primary amino functional group, the N atom is bonded to two H atoms (-NH2). The H atoms can share electron pairs with the N atoms. This sharing relationship means that each H atom provides part of the electron cloud to the N atom, thereby increasing the electron density around the N atom. This means that the N atom is more likely to attract CO2 molecules to undergo electrophilic attack reactions, and the stronger the ability of the N atom to form coordinate bonds with the C atoms in the CO2 molecule, the more stable the carbamate produced by the reaction is, and the less likely it is to undergo decomposition reactions.

[0092] Although embodiments of the present invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and variations can be made to the above embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the claims and their equivalents.

Claims

1. An anhydrous homogeneous carbon dioxide composite amine absorbent based on AEEA-AMP-DMSO, characterized in that, It is composed of the following substances: hydroxyethyl ethylenediamine, isobutanolamine, and dimethyl sulfoxide.

2. The anhydrous homogeneous carbon dioxide composite amine absorbent based on AEEA-AMP-DMSO according to claim 1, characterized in that, The mass fractions of hydroxyethyl ethylenediamine, isobutanolamine, and dimethyl sulfoxide in the absorbent are 16%, 2.5%, and 81.5%, respectively.

3. The anhydrous homogeneous carbon dioxide composite amine absorbent based on AEEA-AMP-DMSO according to claim 2, characterized in that, The absorption load of the absorbent is above 1.

4. The anhydrous homogeneous carbon dioxide composite amine absorbent based on AEEA-AMP-DMSO according to claim 2, characterized in that, The regeneration efficiency of the absorbent is over 97%.

5. The anhydrous homogeneous carbon dioxide composite amine absorbent based on AEEA-AMP-DMSO according to claim 2, characterized in that, The absorption temperature of the absorbent is 40℃.

6. The anhydrous homogeneous carbon dioxide composite amine absorbent based on AEEA-AMP-DMSO according to claim 2, characterized in that, The desorption temperature of the absorbent is 90℃.

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