A method for the preparation of a fly ash-based supported catalyst for catalyzing the desorption of a CO2-rich amine solution

Abstract

The present application relates to CO2 capture and storage technology, disclose a kind of preparation method of fly ash-based supported catalyst applied in catalytic CO2-rich amine solution desorption, including catalyst carrier and catalyst active component, the catalyst carrier is fly ash, the active component is Fe2O3Or Al2O3, catalyst active component accounts for 5~50% of catalyst mass fraction.The present application discloses the preparation method of the above-mentioned catalyst, Fe or Al metal ion is loaded on fly ash by impregnation method, then calcined into metal oxide by high temperature, finally made fly ash-based supported catalyst.The preparation method is simple, material source is extensive, with high stability, low price and catalytic effect is remarkable, not only improves the utilization of resources, realizes the reduction of waste, resource utilization, more effectively reduces the cost of CO2 capture, is a kind of widely used technology.

Description

[0001] Technology Neighborhood

[0002] This invention relates to the field of industrial CO2 emission reduction and control technology, specifically to a method for preparing a fly ash-based supported catalyst for catalyzing the desorption of CO2-rich amine solutions. Background Technology

[0003] Rapid industrial development has consumed vast amounts of fossil fuels (such as coal and oil), while simultaneously emitting large quantities of greenhouse gases, primarily CO2, resulting in an irreversible greenhouse effect. Global warming has become a serious global environmental problem, attracting widespread attention from governments and academia worldwide. Currently, vigorously developing a low-carbon economy to address the severe challenges posed by global warming to human survival and development has become a global consensus. Among carbon capture and storage technologies, CO2 capture is the most crucial and expensive step, accounting for approximately 85% of the total cost. Therefore, developing low-cost, technologically advanced, and easily industrially applicable CO2 capture and storage technologies is of paramount industrial significance.

[0004] Chemical absorption based on organic amine solvents boasts advantages such as high CO2 capture efficiency, high CO2 recovery purity (>99%), and mature technology, making it the technology with the greatest potential for large-scale application at present. However, this technology has several drawbacks: high equipment corrosion rate, organic amine degradation, and high regeneration energy consumption, accounting for more than 60% of the total cost of the CO2 capture process. To address the high energy consumption during the regeneration of CO2-rich amine solvents, researchers have proposed adding a catalyst during the regeneration of CO2-rich amine solutions to reduce energy consumption.

[0005] Synthetically synthesized molecular sieves have long been highly efficient commercial solid catalysts. Liang Zhiwu and Bhatti et al. added molecular sieves to organic solutions, which reduced the heat load by 9-24.3% compared to blank ethanolamine solutions (Bhatti et al. Chem. Eng. J. 2020, 389, 123439; Zhang et al. Appl. Energy 2019, 240, 827-841; Zhang et al. Appl. Energy 2017, 202, 673-684; Liu et al. Ind. Eng. Chem. Res. 2017, 56(27), 7656-7664; Gao et al. Appl. Energy 2020, 259, 114179).

[0006] Bhatti et al. investigated the effect of transition metal oxides (V2O5, MoO3, WO3, ZrO2, TiO2, MnO2, ZnO) on the energy consumption required for the desorption of the rich solution in the regeneration process, and found that transition metal oxides can provide acidic sites in alkaline solution to promote the desorption of MEA solution (Bhatti, et al. ACS Sustainable Chem. Eng, 2017, 5, 5862-5868; Bhatti, et al. ACS Sustainable Chemistry & Engineering. 2018, 6:12079-87.). Monoethanolamine solution is alkaline, and Fe2O3 and Al2O3 are metal oxides, which can provide acidic sites in alkaline solution to promote the desorption of monoethanolamine solution.

[0007] One of the most solid waste generated by coal-fired power plants is fly ash, which has been widely used to manufacture cement, bricks, tiles and road construction facilities. The chemical composition of fly ash includes SiO2, Al2O3, Fe2O3, CaO, K2O, TiO2, SO3, P2O5, MgO, SrO, BaO and other trace components, etc. Due to its high content of SiO2, Al2O3 and other metal oxides, in addition to being a source of many metals, it can also be a catalyst for various chemical reactions. Studies have shown that the use of fly ash as a catalyst is one of the most promising applications of fly ash.

[0008] Table 1 Comparison of desorption performance of different catalysts

[0009] SUMMARY

[0010] The key technical problem solved by the present application is to address the problem of high energy consumption in the regeneration of CO2-rich amine solution by adding a fly ash-based supported catalyst to promote the desorption of CO2-rich amine solution, thereby reducing the energy consumption of CO2 desorption and reducing the cost of CO2 capture, while realizing the resource utilization of waste fly ash. The catalyst uses waste fly ash generated by coal-fired power plants as a carrier and is prepared by impregnation method. The catalyst has excellent catalytic performance, long service life and is much cheaper than traditional molecular sieve catalysts.

[0011] The technical solution of the present application is to provide a fly ash-based supported catalyst for catalyzing the desorption of CO2-rich amine solution, which is composed of a carrier and an active component. The carrier is fly ash, and the active component is Fe2O3 and Al2O3.

[0012] The application provides a fly ash-based supported catalyst for catalyzing CO2-rich amine solution, which takes fly ash, a waste of coal-fired power plants, as a carrier, realizes reduction, resource utilization and harmless utilization of fly ash, and has the advantages of high activity, high recycling times and low cost.

[0013] The application provides a fly ash-based supported catalyst for catalyzing CO2-rich amine solution, which takes fly ash, a waste of coal-fired power plants, as a carrier, realizes reduction, resource utilization and harmless utilization of fly ash, and has the advantages of high activity, high recycling times and low cost.

[0014] As preferred, the catalyst carrier is fly ash generated by a coal-fired power plant. Fly ash is a gray solid waste left after coal in a coal-fired power plant is calcined at high temperature, has a large specific surface area, and is rich in various metal oxides, so that the fly ash can be used as a catalyst carrier, is low in cost, and realizes reduction, resource utilization and harmless utilization of fly ash.

[0015] As preferred, the fly ash is composed of SiO2 26.7%, Al2O3 13%, Fe2O3 4.99%, CaO 3.37%, K2O 1.44%, TiO2 1.13%, SO3 0.723%, P2O5 0.589%, MgO 0.353%, SrO 0.235%, BaO 0.185% and other trace components. Al2O3 and SiO2 are main components of fly ash, have excellent thermal stability and a large specific surface area after high-temperature calcination, and can become a good catalyst carrier.

[0016] The application provides a preparation method of a fly ash-based supported catalyst for catalyzing CO2-rich amine solution, which comprises the following steps:

[0017] (1) calcining fly ash at 300-800 DEG C for 2-6 h to obtain a catalyst carrier;

[0018] (2) dissolving soluble salts of iron or aluminum in ultrapure water to obtain a metal salt solution, and the mass of the metal salt is calculated according to the mass fraction of the metal oxide in the finally prepared catalyst, and the mass fraction is 5-50%;

[0019] (3) adding the catalyst carrier obtained in the step (1) into the salt solution, and the solid-liquid ratio is 1:10-20, then performing constant-temperature impregnation, stirring and steam drying and drying treatment to obtain a solid powder, so as to obtain a precursor A of the catalyst; the impregnation temperature is 30-60 DEG C, the time is 1-12 h, the stirring and steam drying temperature is 40-80 DEG C, the drying temperature is 80-120 DEG C, and the drying time is 8-24 h.

[0020] (4) grinding and calcining the catalyst precursor A obtained in step (3) at a temperature of 300-800°C for 2-6h to obtain the fly ash-based supported catalyst.

[0021] The fly ash is calcined to remove the impurities adsorbed on the surface and obtain a stable catalyst carrier. The calcination temperature is 300-800°C, and the activation effect is good. When the calcination temperature exceeds 800°C, the activation effect is not obvious, and even weakened, which may be due to the internal structure change of the fly ash at high temperature.

[0022] Preferably, the soluble salt solution of iron or aluminum in step (2) is nitrate or chloride, and further preferably iron nitrate or aluminum nitrate. Iron nitrate or aluminum nitrate is relatively low in price and has good solubility in water.

[0023] The impregnation time in step (3) is 1-12h. If the impregnation time is too short, the iron or aluminum salt cannot be fully impregnated on the surface of the fly ash. If the impregnation time is too long, the pore structure of the fly ash is affected, and the catalytic performance is inhibited.

[0024] Preferably, the calcination temperature in step (4) is 300-800°C. Within this range, the loaded metal ions can be fully oxidized to metal oxides. When the calcination temperature is higher than 800°C, the internal structure of the fly ash may change, resulting in a decrease in catalytic activity. If the calcination temperature is too low, the active component cannot be fully reacted into oxides, which may lead to unstable catalyst structure and short service life of the catalyst.

[0025] The calcination time in step (4) is 2-6h. Within this range, the dispersion of the active component after calcination is high, and the catalytic activity is high. If the calcination time is too long, the active component will change, resulting in a decrease in catalytic activity. If the calcination time is too short, the metal salt cannot be fully decomposed, and the metal oxides cannot be fully generated, resulting in a decrease in catalytic effect.

[0026] The application is a fly ash-based supported catalyst for catalyzing the desorption of CO2-rich amine solution. The waste fly ash generated by coal-fired power plants is used as a catalyst carrier, which has the characteristics of high stability, wide source and low price. This application provides an efficient and economic way for the comprehensive utilization of fly ash generated by coal-fired power plants, and realizes the reduction, resource utilization and harmless utilization of fly ash solid waste.

[0027] Experiments on the desorption of CO2-rich amine solution by catalysis show that the addition of the catalyst to the CO2 desorption reaction of rich amine solution can effectively improve the CO2 desorption rate, and has high catalytic activity, long catalytic life and reduced energy consumption by 58.3%.

[0028] Compared with the prior art, the present application has the following technical advantages and catalytic effects:

[0029] (1) The catalyst preparation raw material is widely sourced and low in price.

[0030] (2) The catalyst preparation process is simple and easy to operate.

[0031] (3) The catalyst has superior catalytic desorption performance and higher catalytic performance than traditional molecular sieves and other materials.

[0032] (4) The catalyst is relatively stable and can be well mixed with the amine solvent.

[0033] (5) After adding the catalyst, the amine solvent desorption temperature is low, and the catalyst has no effect on the CO2 absorption performance of the amine solution. The addition of the catalyst does not change the CO2 absorption amount.

[0034] (6) The catalyst has good cycle stability and is easy to separate and recycle. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 shows the cycle regeneration performance of the catalyst in Example 1 DETAILED DESCRIPTION

[0036] Example 1: Al2O3 / FA-50% supported catalyst

[0037] Take 37.164g of aluminum nitrate nonahydrate and add it to 100mL of deionized water, stir until the aluminum nitrate is completely dissolved, then take 5g of the calcined FA in Comparative Example 1 and add it to the aluminum nitrate solution, stir in a water bath at 40℃ for 0.5h, then soak for 8h, then steam dry at 65℃. Put the steam-dried product into a drying box and dry at 110℃ for 12h. Finally, grind the dried product in a mortar, sieve, and put it into a muffle furnace and heat it to 500℃ at a heating rate of 5℃ / min, calcine for 4h, and naturally cool and store for later use. The catalyst prepared by this method is marked as Al2O3 / FA-50%.

[0038] Comparative Example 1: FA catalyst

[0039] Take 10g of raw fly ash and place it in a muffle furnace, heat it to 500℃ at a heating rate of 5℃ / min, calcine for 4h, and naturally cool and store for later use. The fly ash prepared by this method is simply marked as FA.

[0040] Comparative Example 2: Al2O3 catalyst

[0041] Take 37.164g of aluminum nitrate nonahydrate and place it in a muffle furnace, heat it to 500℃ at a heating rate of 5℃ / min, calcine for 4h, and naturally cool and grind it in a mortar, sieve, and store for later use. The catalyst prepared by this method is marked as Al2O3.

[0042] Example 2: Fe2O3 / FA-50% supported catalyst

[0043] The same as example 1, except that 25.684 g of iron nitrate nonahydrate was added during the catalyst preparation process, and the prepared catalyst was marked as Fe2O3 / FA-50%.

[0044] Application example

[0045] Catalytic desorption of CO2-rich monoethanolamine solvent

[0046] The absorption experiment was carried out by placing a freshly prepared 5 mol / L ethanolamine (MEA) solution into a 40°C constant temperature water bath, and passing 200 ml / min of pure CO2 gas to saturate the MEA solution with CO2. The CO2 loading of the saturated MEA solution was determined by titration with 1 mol / L HCl. The CO2 loading of the MEA solution was adjusted to be 0.53 mol CO2 / mol amine.

[0047] The heating device used in the desorption experiment was an intelligent magnetic stirring electric heating jacket. The reactor was a 500 mL three-necked flask. The CO2-saturated MEA solution was placed in the three-necked flask. The neck in the middle of the three-necked flask was connected to a condenser tube, and the other neck was inserted into the temperature probe of the electric heating jacket to detect the temperature of the solution in real time during the regeneration and desorption of CO2. The third neck was tightly plugged with a glass stopper to prevent gas leakage. At the beginning of the experiment, 200 mL of the MEA solution with the desired initial CO2 loading (e.g., 0.53 mol CO2 / mol amine) was added to the reactor. The regeneration temperature was 80-100°C. During the desorption process, 0.25-1.25 wt% of the fly ash-based supported catalyst was added. After the desorption was completed, the CO2-lean MEA solution was cooled to room temperature, and then CO2 was introduced again for absorption saturation, followed by desorption. The absorption and desorption cycle was repeated for 20 times.

[0048] The concentration of the MEA solution used in the desorption was 5 mol / L. The catalysts used were the FA catalyst, the Al2O3 catalyst, the Fe2O3 / FA-50% catalyst, and the Al2O3 / FA-50% catalyst prepared in the above examples and comparative examples. The specific experimental procedure was as follows: open the mass flowmeter, adjust the mass flow of nitrogen to 500 ml / min, and take a new three-necked flask to replace the air in the device. Then, the CO2-saturated MEA solution was transferred from the water bath to the three-necked flask containing 0.5 g of the above catalyst, and the flask mouth was plugged with a glass stopper. The intelligent magnetic stirring electric heating jacket was heated to 88°C, and was connected in series with an electric energy meter. The electric energy meter was used to record the consumed electric energy, which was used to calculate the relative energy consumption of the CO2 desorption process.

[0049] The Al203 / FA-50% catalyst was tested for its cyclic regeneration performance. The lean amine solution after desorption was cooled and recharged with CO2 for absorption. After absorption, the loaded amine solution was desorbed again. The above steps were repeated for 20 times. The absorption conditions were: room temperature, gas flow rate of 300 ml / min CO2 and 200 ml / min N2, absorption time of 60 min, and final loading of 0.53 (±0.01) mol CO2 / mol amine. The desorption conditions were: temperature of 88°C, catalyst dosage of 0.25 wt%, gas flow rate of 500 ml / min N2, and desorption time of 60 min.

[0050] The experimental results are shown in the following table:

[0051] Table 2 Comparison of relative energy consumption for desorption of catalysts in examples

[0052]

[0053] As shown in the above table, the energy consumption for desorption of the amine solvent is significantly reduced after adding the catalyst relative to the blank MEA, and the catalytic performance of the supported catalyst prepared in the examples is superior to that of the FA catalyst without loading of metal.

Claims

1. Use of a fly ash-based supported catalyst in catalyzing the desorption of a CO2-rich amine solution, said fly ash-based supported catalyst comprising a catalyst support and a catalyst active component, characterized in that, The catalyst carrier is fly ash, the catalyst active component is Fe2O3 or Al2O3, and the catalyst active component accounts for 5-50% of the mass fraction of the catalyst; The main components of the fly ash include SiO2 26.7%, Al2O3 13%, Fe2O3 4.99%, CaO 3.37%, K2O 1.44%, TiO2 1.13%, SO3 0.723%, P2O5 0.589%, MgO 0.353%, SrO 0.235%, BaO 0.185%, and other trace components.

2. Use according to claim 1, characterized in that, Metal oxides are loaded on fly ash by an impregnation method, and the loaded metal oxides are abbreviated as M x O y The preparation steps of the fly ash-based supported catalyst are as follows: (1) calcining the fly ash at 300-800 DEG C for 2-6 hours to obtain a catalyst carrier; (2) dissolving soluble salts of iron or aluminum in ultrapure water to obtain a metal salt solution; the mass of the metal salt is calculated according to the mass fraction of the metal oxide in the finally prepared catalyst, and the mass fraction is 5-50%; (3) adding the catalyst carrier obtained in step (1) to the above salt solution, and the solid-liquid ratio is 1g: 10-20ml, then performing constant temperature immersion, stirring, steam drying and drying treatment to obtain a solid powder, thereby obtaining a catalyst precursor A; the immersion temperature is 30-60 DEG C, the time is 1-12 hours, the stirring and steam drying temperature is 40-80 DEG C, the drying temperature is 80-120 DEG C, and the drying time is 8-24 hours; (4) grinding and calcining the solid catalyst precursor A obtained in step (3) at a calcining temperature of 300-800 DEG C for 2-6 hours, thereby obtaining the fly ash-based supported catalyst.

3. Use according to claim 2, characterized in that, The soluble salt of iron or aluminum in step (2) is a nitrate salt or a chloride salt.

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