Alpha-fe2o3 material for reducing carbon capture energy consumption and preparation method and application thereof

Abstract

The application discloses an alpha-Fe2O3 material for reducing carbon capture energy consumption and a preparation method and application thereof, the alpha-Fe2O3 material is obtained by calcining iron nitrate as raw material in a muffle furnace at high temperature. The application of the alpha-Fe2O3 material in the method steps of the organic amine desorption CO2 regeneration process is as follows: after CO2 absorption in the organic amine aqueous solution, liquid-liquid phase separation is carried out, and the CO2 enrichment phase is collected; the metal oxide alpha-Fe2O3 catalyst is added into the CO2 enrichment phase, and CO2 is desorbed at 90-95 DEG C, so that the regeneration of the organic amine at low energy consumption is realized. The preparation method of the alpha-Fe2O3 material is simple, the alpha-Fe2O3 material obtained can accelerate the CO2 desorption rate of the organic amine, improve the regeneration efficiency of the organic amine loaded with CO2, reduce the regeneration energy consumption, solve the technical bottleneck of the organic amine capturing CO2, and help to reach the carbon peak.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of catalysis, and particularly relates to an α-Fe2O3 material for reducing carbon capture energy consumption and a preparation method and application thereof. BACKGROUND

[0002] For the capture of carbon dioxide greenhouse gas, the most widely studied post-combustion capture technology is to use an alkaline solvent to absorb CO2 emitted at a fixed point, so as to achieve the effect of capturing CO2 from flue gas. The advantage of this technology is strong applicability, without the need to modify existing units and other equipment, and the technology is mature and has rich application cases. The main bottlenecks faced by this technology are two aspects, one is that the amount of CO2 gas in the flue gas is large and the partial pressure is low, so it is necessary to develop and use a solvent with high selectivity for CO2 absorption.

[0003] At present, mixed amine phase change absorbent is a hot research direction of new absorption technology development. Such phase change absorbents are generally composed of a primary amine with high reactivity and a tertiary amine or a hindered amine with large absorption capacity and low reaction heat, and have the advantages of fast absorption rate, large absorption capacity, and low regeneration energy consumption. The reason for low regeneration energy consumption is that 1) a large amount of tertiary amine is mixed in the phase change absorbent, which has low reaction heat, thereby reducing the reaction heat; 2) after CO2 absorption, liquid-liquid phase separation occurs, and more than 90% of the CO2 absorption product is enriched in one phase, so only the CO2-rich phase needs to be regenerated to realize the regeneration of the absorbent, thereby greatly reducing the sensible heat; 3) the CO2 equilibrium partial pressure of the rich phase is high, which greatly reduces the evaporation heat. Furthermore, due to the reduced mass of the absorbent to be regenerated, the size of the desorption tower can be reduced, further reducing the fixed investment cost.

[0004] In summary, mixed amine phase change absorbents are considered to be a new generation of absorbents that are expected to be industrialized. Previous studies have shown that the phase separation mechanism is that after the primary amine absorbs CO2, carbamate and protonated organic amine are generated, which increases the ionic strength of the solution, and then liquid-liquid phase separation occurs due to the "salting out" effect. Compared with MEA, the above phase change absorbent exhibits excellent performance such as large absorption capacity, fast absorption rate, and low regeneration energy consumption. However, the key technology of both single-phase solvent and mixed two-phase solvent is the regeneration process of the absorbent, and the traditional thermal regeneration has the problem of high energy consumption.

[0005] The CO2 capture method adopted by the prior art uses metal organics to reduce the regeneration energy consumption of organic amine solvents, which is expected to overcome the bottleneck of the technology. However, the existing catalyst preparation process is complicated, the raw material price is high, and its performance is not enough to reduce the regeneration energy consumption to a low level. In order to further improve the CO2 desorption rate of organic amines, reduce the regeneration energy consumption, reduce the cost of CO2 capture of organic amines, and enhance the practicability of the organic amine absorption method, it is of great market value and economic significance to research and develop solid catalysts with low price, high catalytic performance and strong stability for the generation of organic amines. SUMMARY

[0006] In view of the above technical problems existing in the prior art, the purpose of the present application is to provide an α-Fe2O3 material for reducing carbon capture energy consumption and a preparation method and application thereof. The preparation method of the α-Fe2O3 material of the present application is simple, and the obtained α-Fe2O3 can accelerate the CO2 desorption rate of organic amines, improve the regeneration efficiency of organic amines loaded with CO2, reduce the regeneration energy consumption, solve the technical bottleneck of CO2 capture of organic amines, and help to achieve the goal of "carbon peak".

[0007] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is:

[0008] The preparation method of the α-Fe2O3 material for reducing carbon capture energy consumption is to use iron nitrate as raw material and obtain metal oxide α-Fe2O3 by high-temperature calcination in a muffle furnace.

[0009] Further, the process of high-temperature calcination is: after programmed heating from room temperature to 400-700℃, constant temperature is maintained for 3-8h, and finally natural cooling to room temperature, the programmed heating rate is 2-10℃ / min.

[0010] Further, in the process of high-temperature calcination, the constant temperature is 500-600℃, the constant temperature maintaining time is 4-5h, and the programmed heating rate is 4-5℃ / min.

[0011] The α-Fe2O3 material for reducing carbon capture energy consumption is used as a catalyst in the application of reducing the regeneration energy consumption of organic amine desorbing CO2.

[0012] The application method of the present application for reducing the regeneration energy consumption of organic amine desorbing CO2 includes the following steps:

[0013] 1) CO2 is introduced into an aqueous organic amine solution containing primary amine and tertiary amine;

[0014] 2) After CO2 absorption in step 1), liquid-liquid phase separation is carried out, and the CO2-rich phase is collected;

[0015] 3) The metal oxide α-Fe2O3 catalyst is added to the CO2-rich phase to react and desorb CO2 at 90-95℃, thereby realizing regeneration of the organic amine at low energy consumption.

[0016] Further, in step 1), the aqueous organic amine solution comprises TETA and DEEA, the molar ratio of TETA to DEEA is 0.5-2:3, preferably 1:3, and the total amine concentration of the aqueous organic amine solution is 2-6 mol / L, preferably 4 mol / L.

[0017] Further, in step 2), the absorption amount of CO2 in the aqueous organic amine solution is greater than or equal to 0.75 mol CO2 / mol amine solution.

[0018] Compared with the prior art, the present application has the following beneficial effects:

[0019] 1) The α-Fe2O3 catalytic material of the present application is simple to prepare, requires less equipment investment and has low cost.

[0020] 2) The metal oxide α-Fe2O3 catalyst of the present application is used in the regeneration process of the TETA / DEEA representative two-phase solvent, which can effectively improve the problems of low desorption efficiency and high regeneration energy consumption. The catalytic effect of the catalyst on desorption of CO2 from the organic amine is better than that of the ordinary molecular sieve catalyst. The energy consumption of the amine solution for desorption of CO2 is reduced by 45.2% in one hour, and the amount of desorbed CO2 is increased by 84.3% under the same experimental conditions.

[0021] 3) The α-Fe2O3 catalyst of the present application has high catalytic stability and can be used cyclically, and the energy efficiency is higher than 85% after five cycles. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 Figure 4 is the XRD pattern of the four catalysts in Example 1.

[0023] Figure 2 Figure 5 is a scanning electron microscope picture (SEM) of the four catalysts in Example 1.

[0024] Figure 3 Figure 6 is a graph of the desorption amount and relative energy consumption of the metal oxide α-Fe2O3 catalyst prepared at different temperatures in Example 2. IMPLEMENTATION

[0025] The present application will be further described below in conjunction with specific examples, but the scope of protection of the present application is not limited thereto. EXAMPLE

[0026] The application relates to a preparation method of an alpha-Fe2O3 material for reducing carbon capture energy consumption, in particular to the following steps: taking iron nitrate nonahydrate as raw material, high-temperature calcining in a muffle furnace, the high-temperature calcining process is as follows: 5 DEG C / min program temperature rising, from room temperature to constant temperature calcining temperature, then constant temperature keeping for 5 hours, and finally natural cooling to room temperature. According to the above preparation method, the catalyst materials prepared at the constant temperature calcining temperatures of 400 DEG C, 500 DEG C, 600 DEG C and 700 DEG C are marked as 400 DEG C alpha-Fe2O3, 500 DEG C alpha-Fe2O3, 600 DEG C alpha-Fe2O3 and 700 DEG C alpha-Fe2O3 respectively.

[0027] The XRD patterns of the four alpha-Fe2O3 materials calcined at 400-700 DEG C in Example 1 are shown in Figure 1 The XRD patterns of the four alpha-Fe2O3 materials calcined at 400-700 DEG C in Example 1 are shown in Figure 1 It can be known from

[0028] The SEM photos of the four alpha-Fe2O3 materials calcined at 400-700 DEG C in Example 1 are shown in Figure 2 It can be known that the morphology structure of the metal oxide alpha-Fe2O3 prepared at different temperatures is difficult to control and is easy to agglomerate. The particle distribution of the 600 DEG C alpha-Fe2O3 material is relatively uniform.

[0029] Example 2: Influence of metal oxide alpha-Fe2O3 catalysts prepared at different temperatures on CO2 desorption of mixed phase change absorbent TETA / DEEA

[0030] A 300ml three-necked flask is used as the reactor, the left side is sealed, the right side neck is provided with a thermometer for measuring the real-time temperature of the amine solution; the middle neck is a 300ml serpentine condenser, ice blocks are used for cooling as condensing water to prevent loss of the amine solution, and the condenser is connected with a soap flow meter through a rubber hose; the right side neck is closed with a rubber plug to ensure the air tightness of the device. The temperature of the amine solution is provided by an oil bath, and the magnetic stirring speed is set to 300 revolutions per minute to ensure sufficient contact between the amine solution and the catalyst.

[0031] The method for desorbing CO2 of the mixed phase change absorbent TETA / DEEA in Example 2 comprises the following steps:

[0032] 1) The organic amine aqueous solution is a TETA and DEEA aqueous solution with a molar ratio of 1:3, and the total amine concentration of the organic amine aqueous solution is 4mol / L. CO2 is introduced into 300ml of the organic amine aqueous solution until the CO2 loading in the organic amine aqueous solution is 0.75mol CO2 / mol amine solution. After CO2 absorption by the method, liquid-liquid phase separation is carried out, and the CO2-rich phase is collected.

[0033] 2) Take 200 mL of the CO2-rich phase obtained in step 1) into a three-necked flask, and add the catalyst at a ratio of 1.25 g:100 mL (the blank control refers to no catalyst being added). Place the three-necked flask in an oil bath, heat the amine solution to 94°C, and react for 1 h. The desorbed CO2 gas passes through a condenser tube to a soap film flowmeter, and the desorption rate of CO2 at a certain time point is calculated according to the time required for the soap bubble to rise 100 mL (the rising volume of the soap bubble V (100 mL), the time t (s), and the desorption rate of V / t at the time point t (L / min)).

[0034] Under the same experimental conditions, the amount of desorbed CO2 without catalyst for 1 h is 0.1665 mol (defined as 100% as a control value) according to the above method, and the results of the amount of desorbed CO2 obtained by using the four α-Fe2O3 materials calcined at 400-700°C in Example 1 for 1 h are summarized in Table 1 (the results of the amount of desorbed CO2 are shown in the bar chart in FIG. 1, corresponding to the vertical coordinate on the left side). Figure 3 Figure 3 The amount of desorbed CO2 using the metal oxide α-Fe2O3 catalyst material in Example 1 is increased by 84.3%.

[0035] The energy consumption value is defined as the energy required to desorb one mole of CO2 (kJ / mol), and the energy consumption ratio of the group without catalyst (i.e., the blank control) is defined as 100%. The energy is the amount of electricity consumed during the experiment, which is converted to kJ. The results of the energy consumption obtained by using the four α-Fe2O3 materials calcined at 400-700°C in Example 1 for desorption are summarized in Table 2 (the results of the energy consumption are shown in the dot chart in FIG. 2, corresponding to the vertical coordinate on the right side). Figure 3 Figure 3 The relative energy consumption of the catalyst material of the present application is reduced by more than 45.2%.

[0036] The 600°C α-Fe2O3 material of the present application is used for a cyclic desorption experiment. After each desorption reaction for 1 h, the solid material is collected by centrifugation, dried, and directly used in the next experiment. After five cycles, the amount of desorbed CO2 using the 600°C α-Fe2O3 material for 1 h becomes 261.2 mol, and the relative energy consumption changes to 64.3%. The energy consumption ratio of the group without catalyst (i.e., the blank control) is defined as 100%.

[0037] The content described in the specification is only a list of forms of the inventive concept, and the protection scope of the present application should not be considered to be limited to the specific forms described in the examples.​​

Claims

1. The use of a-Fe2O3 material for reducing the energy consumption of carbon capture as a catalyst in reducing the energy consumption of the regeneration of organic amine desorbing CO2, characterized by The preparation method of the alpha-Fe2O3 material is to use ferric nitrate as raw material, and to obtain the metal oxide alpha-Fe2O3 by high-temperature calcination in a muffle furnace, the high-temperature calcination process is: from room temperature to 500-600 DEG C, and then keep constant temperature for 4-5 hours, and finally, natural cooling to room temperature, the programmed heating rate is 4-5 DEG C / min; The organic amine is an aqueous solution of organic amine containing primary amine and tertiary amine, the aqueous solution of organic amine contains TETA and DEEA, and the molar ratio of TETA and DEEA is 0.5-2:

3.

2. Use according to claim 1, wherein The application method comprises the following steps: 1) introducing CO2 into the aqueous solution of organic amine containing primary amine and tertiary amine; 2) after CO2 absorption in step 1), liquid-liquid phase separation is carried out, and the CO2-rich phase is collected; 3) the metal oxide alpha-Fe2O3 catalyst is added into the CO2-rich phase, and CO2 is desorbed by reaction at 90-95 DEG C, so as to realize regeneration of the organic amine at low energy consumption.

3. Use according to claim 2, wherein In step 1), the total amine concentration of the aqueous solution of organic amine is 2-6 mol / L.

4. The use according to claim 2, wherein In the aqueous solution of organic amine, the molar ratio of TETA and DEEA is 1:3, and the total amine concentration of the aqueous solution of organic amine is 4 mol / L.

5. The use according to claim 1, characterized in that In step 2), the absorption amount of CO2 in the aqueous solution of organic amine is greater than or equal to 0.75 mol CO2 / mol amine solution.

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