Application of mesoporous silica core-shell catalyst in catalysis of carbon dioxide desorption

Abstract

The invention discloses an application of a mesoporous silica (mSiO2) coated metal oxide nanoparticle (MxOy at mSiO2) core-shell structure catalyst in catalysis of CO2 desorption. The preparation method of the core-shell type catalyst MxOy (at) mSiO2 comprises the following steps: firstly, preparing nano metal hydroxide particles by a one-pot method, and then covering the surfaces of the nano particles with a SiO2 layer to prepare the core-shell type catalyst MxOy (at) mSiO2. According to the prepared core-shell type MxOy-mSiO2, agglomeration and loss of active components in the reaction process can be effectively prevented through protection of a shell layer, the stability of the catalyst is improved, and the service life of the catalyst is prolonged. The catalyst provided by the invention has a unique core-shell structure, so that the catalyst has excellent CO2 desorption catalysis performance and excellent stability. In addition, the catalyst has small influence on CO2 absorption performance of an amine solution.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of CO2 capture in coal-fired power plants, and particularly relates to application of mesoporous silica core-shell catalyst in catalytic CO2 desorption. BACKGROUND

[0002] Since the industrial revolution, large-scale consumption of fossil energy has led to a sharp increase in CO2 emissions, which has triggered global warming and exacerbated the greenhouse effect. In December 2015, nearly 200 countries signed the Paris Agreement under the United Nations Framework Convention on Climate Change, establishing the goal of controlling the global average temperature within 2℃ in this century. China's energy structure is still dominated by coal, with the highest coal consumption in the world and the highest annual CO2 emissions. Among numerous low-carbon emission reduction technologies, CO2 capture, utilization and storage (CCUS) technology is considered a key solution. Among them, the chemical absorption method with organic amine solution as the absorbent has become the most mature, widely used and most potential CO2 capture method due to its low cost, fast absorption rate, large absorption capacity and recyclable solution. However, the current technology faces bottlenecks in practical application. The regeneration process of traditional rich amine solution desorbing CO2 requires high-temperature conditions, and the energy consumption is huge, accounting for more than 60% of the total cost of CO2 capture. Therefore, exploring effective methods to reduce the heat energy consumption of CO2 capture process is of great significance to promote the large-scale application of organic amine solution CO2 capture technology in coal-fired power plants and achieve deep carbon reduction in the coal-fired power generation industry.

[0003] In view of the problem of high temperature (120-140℃) of rich CO2 amine solution regeneration energy consumption, Bhatti et al. reported that adding V2O5, MoO3, WO3, ZrO2, TiO2, MnO2, ZnO and other metal oxide catalysts can reduce the heat load of 5M ethanolamine solution (MEA) regeneration by about 20-48%.(Umair H. Bhatti et al. ACS Sustainable Chemistry & Engineering, 2017, 5(7): 5862-8). Liang Ziwu et al. proposed adding metal oxide supported sulfate type solid superacid catalysts, which can reduce the regeneration heat load of 5M MEA solution by about 40% at 98℃ (CN106984333A).

[0004] Most of the existing catalysts are prepared by simple impregnation or co-precipitation method, but the problem of the supported catalysts is that the active components are easy to flow out in the reaction process, and the reaction solvent is mostly alkaline solution, and the reaction of metal oxides with the alkaline solution further aggravates the flow out of the active components of the catalyst. In order to further reduce the regeneration energy consumption of the CO2-rich amine solution, and then reduce the CO2 capture cost, and improve the practicability of the amine method for capturing CO2, it has great practical significance to develop and design a new type of high-efficiency solid acid catalyst applied to the regeneration process of the CO2-rich amine solution. The present application aims to provide a MxOy@mSiO2 catalyst with a core-shell structure, which can prevent the agglomeration and flow out of the active components in the catalytic desorption reaction process, improve the stability of the catalyst, and prolong the service life of the catalyst under the premise of maintaining the high-efficiency catalytic performance of the catalyst. SUMMARY

[0005] The technical problem to be solved by the present application is to synthesize a core-shell catalyst with superior performance, and to be used for catalytically reducing the regeneration energy consumption of the CO2-rich organic amine solution, so as to reduce the cost of the organic method for capturing CO2.

[0006] The technical scheme of the present application is to provide an application of a MxOy@mSiO2 core-shell catalyst in catalyzing the desorption of CO2 from an organic amine solution, characterized in that the oxide is an acidic or amphoteric metal oxide; and the preparation method of the catalyst is as follows:

[0007] (1) Dissolve the soluble metal salt and the surfactant in water or alcohol solution to obtain solution A; add an alkaline substance to increase the pH value of solution A, so that the metal salt is precipitated, and a mixed solution B is obtained;

[0008] (2) After the B solution is ultrasonically treated for a period of time, tetraethyl orthosilicate is added, and the obtained solution is stirred in a water bath for a period of time. The obtained solution is filtered, washed with ethanol and dried, and then ground to obtain a solid powder C.

[0009] (3) The solid powder C is calcined for a period of time to obtain MxOy@mSiO2.

[0010] Preferably, in step (1), the pH value is 6-12.

[0011] Preferably, in step (2), the ultrasonic treatment time is 0-20h, and the ultrasonic treatment temperature is 10-50℃.

[0012] Preferably, in step (2), the drying temperature is 40-200℃, and the drying time is 1-48h.

[0013] Preferably, the molar ratio of the metal salt to tetraethyl orthosilicate is 1:5-5:1.

[0014] Preferably, in step (3), the calcination temperature is 300-800℃, and the calcination time is 2-12h.

[0015] Preferably, the oxide is one or more of acidic oxide or amphoteric oxide TiO2, CuO, Fe2O3, SnO2, NiO, ZrO2, ZnO, Cr2O3, V2O5, MoO3, WO3, Al2O3, CoO.

[0016] Preferably, in step (2), the heating temperature is 40-130℃, and the stirring time is 0.5-8h.

[0017] The present technology has the following advantages:

[0018] (1) The catalyst preparation process is simple, and the raw materials are cheap and easy to obtain.

[0019] (2) The catalyst has excellent desorption performance and stronger catalytic performance than traditional catalysts such as single metal oxide, molecular sieve, and mSiO2.

[0020] (3) The catalyst has good stability and good repeat cycle performance.

[0021] (4) Through the protection of the core-shell, the agglomeration and loss of active components during the reaction process are prevented, the stability of the catalyst is improved, and the service life of the catalyst is prolonged. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 Indicates a laboratory-scale batch desorption device for CO2-rich amine solution.

[0023] Figure 2 Indicates the X-ray diffraction spectrum of the catalyst in the example.

[0024] Figure 3 Indicates the N2adsorption-desorption curve of the catalyst in the example.

[0025] Table 1: Comparison of energy consumption of catalyst desorption of examples and control examples. DETAILED DESCRIPTION

[0026] The present application will be further described below in conjunction with examples.

[0027] Example 1: Al2O3@mSiO2catalyst

[0028] First, 450 mL of deionized water was added into a 1000 mL three-neck flask, 1.0 g of CTAB was added, and the solution was stirred at 95 °C for 30 min. Second, 20 mL of 0.05 mol / L aluminum nitrate solution was added, and the solution was stirred at 95 °C for 1 h. Third, 1 mol / L NaOH solution was added dropwise to adjust the solution pH to 11. Fourth, the solution was stirred for 5 min, and then 8 mL of TEOS was added dropwise. The solution gradually turned white, and the solution was stirred for 3 h, followed by overnight standing. Fifth, the resulting solution was centrifuged and washed to neutral, and then centrifuged with anhydrous ethanol to remove residual CTAB. Sixth, the resulting precipitate was dried in an oven at 80 °C for 12 h, and then calcined in a muffle furnace at 500 °C for 4 h with a heating rate of 5 °C / min. The resulting catalyst was designated as Al2O3@mSiO2.

[0029] Comparative Example 1: mSiO2 catalyst

[0030] As a comparison, the mSiO2 catalyst was prepared in a similar way as Al2O3@mSiO2, except that no nitrate salt was added.

[0031] Example 2: NiO@mSiO2 catalyst

[0032] Similar to Example 1, except that the metal salt used was nickel nitrate, and the resulting catalyst was designated as NiO@mSiO2.

[0033] Example 3: ZrO2@mSiO2 catalyst

[0034] Similar to Example 1, except that the metal salt used was zirconium nitrate, and the resulting catalyst was designated as ZrO2@mSiO2.

[0035] Application Example

[0036] Catalytic desorption of CO2-rich monoethanolamine solvent regeneration process

[0037] A laboratory-scale batch desorption apparatus for CO2-rich amine solution was constructed as shown in Figure 1. Figure 1As shown, the main body is a 500ml three-necked flask with a thermometer inserted in the middle. A reflux condenser is installed on the right side of the flask to prevent the amine solution from evaporating, and a gas inlet is located on the left. The three-necked flask contains a magnetic stir bar, and an oil bath with magnetic stirring is located below the flask. Desorption energy consumption (KJ / mol) is defined as the energy required to desorb 1 mol of CO2, calculated using an electric meter. The heat is provided by the oil bath. The amine solution used for desorption is a 5mol / L monoethanolamine solution (MEA) with a rich amine loading of 0.52 CO2 / mol amine. The catalyst used is prepared by the method described above. The specific operation process is as follows: 200ml of the CO2-rich MEA solution to be desorbed is added to the flask, and 0.5g of the above-mentioned catalyst is added at a ratio of 0.25%. The three-necked flask is placed in the oil bath and heated to the required desorption temperature of 88℃.

[0038] Table 1 shows the comparison results of catalyst energy consumption in the examples and comparative examples. As can be seen from the table, compared with the blank energy consumption, the relative energy consumption of mSiO2 is 68%, while that of Al2O3@mSiO2, NiO@mSiO2, and...

[0039] The relative energy consumption of ZrO2@mSiO2 was 49%, 56%, and 60%, respectively. The Al2O3@mSiO2 catalyst showed the best catalytic effect, with a relative energy consumption reduction of 51%.

[0040] XRD and N2 adsorption-desorption tests were performed on the catalyst in the example, and the results were as follows: Figure 2 and Figure 3 .from Figure 2 As can be seen, the Al2O3@mSiO2, NiO@mSiO2, and ZrO2@mSiO2 catalysts all exhibit diffraction peaks for SiO2, while no diffraction peaks for other oxides are observed, indicating that the oxides are uniformly coated with SiO2. From... Figure 3 As can be seen, all four catalysts exhibit type IV adsorption isotherms, indicating that they all possess mesoporous structures.

[0041] The above description provides an illustrative overview of the present invention and its embodiments, and is not restrictive. The embodiments shown are merely one example of the present invention, and the implementation of the reagents is not limited thereto. Therefore, if those skilled in the art are inspired by this description and, without departing from the spirit of the invention, design similar embodiments and examples without creative effort, all such embodiments and examples should fall within the protection scope of the present invention.

[0042] Table 1 Comparison of catalyst energy consumption in the examples and comparative examples.

[0043] Catalyst Energy consumption ratio (%) Energy consumption reduction (%) Blank 100 0 Comparative Example 1 : mSiO2 68 32 Example 1 : Al203@mSi02 49 51 Example 2: NiO@mSiO2 56 44 Example 3: Zr02@mSi02 60 40

Claims

1. Use of mesoporous silica encapsulated metal oxide nanoparticle (MxOy@mSiO2) core-shell catalysts in catalyzing the desorption of CO2 from organic amine solutions, characterized in that, The oxide is an acidic or amphoteric metal oxide; the preparation method of the catalyst is as follows: (1) dissolving a soluble metal salt and a surfactant in water or alcohol solution to obtain solution A; adding a basic substance to increase the pH value of solution A, so that the metal salt is precipitated, and a mixed solution B is obtained; (2) after ultrasonic treatment of B solution for a period of time, tetraethyl silicate is added, and stirring is carried out in a water bath for a period of time. The obtained solution is filtered, washed with ethanol and dried and ground to obtain solid powder C. (3) calcining solid powder C for a period of time to obtain the target catalyst MxOy@mSiO2.

2. Use according to claim 1, characterized in that, In step (1), the pH is 6-12.

3. Use according to claim 1, characterized in that, In step (2), the ultrasonic treatment time is 0-20h, and the ultrasonic treatment temperature is 10-50℃.

4. Use according to claim 1, characterized in that, In step (2), the drying temperature is 40-200℃, and the drying time is 1-48h.

5. The use according to claim 1, characterized in that, The molar ratio of the metal salt to tetraethyl silicate is 1:5-5:

1.

6. Use according to claim 1, characterized in that, In step (3), the calcination temperature is 300-800℃, and the calcination time is 2-12h.

7. Use according to claim 1, characterized in that, The oxide is one or more of acidic oxides or amphoteric oxides TiO2, CuO, Fe2O3, SnO2, NiO, ZrO2, ZnO, Cr2O3, V2O5, MoO3, WO3, Al2O3, CoO.

8. The use according to claim 1, characterized in that, In step (2), the heating temperature is 40-130℃, and the stirring time is 0.5-8h.

Images