Multifunctional composite material based on fly ash mineralization for CO2 storage and preparation method thereof

Abstract

The application discloses a multifunctional composite material based on fly ash mineralization CO2 storage and a preparation method thereof. The material is composed of high-activity fly ash treated by plasma activation, nanoscale metal oxide catalyst, metal organic framework, functional organic ligand, intelligent pH regulator, solid suspension stabilizer and water. The preparation method comprises the following steps: suspension preparation, high-pressure CO2 mineralization reaction in a reaction kettle, centrifugal separation and freeze-drying treatment. The method is simple, and the raw material cost is low. The prepared multifunctional composite material can not only significantly improve the storage efficiency of CO2, but also ensure the generation of stable carbonate products. The carbonate products have high specific surface area and excellent chemical stability, and can be widely applied to high-end building materials, energy storage materials and fine chemical industry. Meanwhile, the multifunctional composite material realizes high-value utilization of fly ash, an industrial by-product, and achieves the dual goals of reducing carbon emission and improving the utilization rate of solid waste.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of carbon dioxide capture and storage (CCS), in particular to a multifunctional composite material for mineralization and storage of CO2 based on fly ash and a preparation method thereof, and belongs to the cross field of environmental engineering, solid waste resource utilization and green low-carbon technology. BACKGROUND

[0002] With the increasingly serious global climate change problem, carbon dioxide (CO2), as one of the main greenhouse gases, has more and more obvious negative effects on the environment. In order to effectively reduce the emission of CO2, carbon dioxide capture and storage (CCS) technology has gradually become one of the important strategies for addressing climate change worldwide. However, the existing CO2 storage technology has many challenges in terms of economy and sustainability, especially the problems of low storage efficiency, high cost and insufficient long-term stability. In addition, with the rapid development of global industrialization, the emission of industrial by-products such as fly ash is increasing year by year, and how to efficiently and environmentally utilize these wastes has become an important issue to be solved in the fields of industry and environmental protection.

[0003] Fly ash is the main waste of coal-fired power plants, which contains rich silicon, aluminum and active calcium oxide, and has the potential to react with CO2. Fly ash mineralization and storage of CO2 not only can effectively reduce the emission of greenhouse gases, but also can realize the resource utilization of solid waste. However, the traditional fly ash mineralization CO2 technology still has a lot of room for improvement in terms of reaction efficiency and product stability. In order to improve the storage efficiency of CO2, accelerate the reaction rate, and improve the stability and added value of the product, it is imperative to study more efficient catalysts, multifunctional auxiliary materials and innovative mineralization reaction processes. SUMMARY

[0004] The purpose of the present application is to provide a multifunctional composite material for mineralization and storage of CO2 based on fly ash and a preparation method thereof. The method is simple, the raw material cost is low, the prepared multifunctional composite material can not only significantly improve the storage efficiency of CO2, but also ensure the generation of stable carbonate products, and at the same time realize the high value-added utilization of fly ash, an industrial by-product, achieving the dual goals of reducing carbon emissions and improving the utilization rate of solid waste.

[0005] To achieve the above purpose, the present application provides a multifunctional composite material for mineralization and storage of CO2 based on fly ash, which is composed of the following raw materials by mass: fly ash treated by plasma activation 70-85 parts, nano-sized metal oxide catalyst 3-7 parts, metal organic framework functionalized organic ligand ZIF-8 type MOF 5-10 parts, intelligent pH regulator poly(acrylic acid-co-acrylamide) copolymer 1-2 parts, solid suspension stabilizer 3-5 parts, and high-purity water 10-20 parts.

[0006] The plasma-activated fly ash contains 50-65wt% of SiO2, 20-30wt% of Al2O3 and 5-15wt% of CaO.

[0007] The preparation process of the nanoscale metal oxide catalyst is as follows: calcium oxide, magnesium oxide and zinc oxide are weighed according to the proportion, ball-milled and mixed to obtain a mixed powder, the mixed powder is calcined at high temperature to form a composite oxide, and then the composite oxide is placed in a graphene dispersion liquid and ultrasonically dispersed, so that the graphene uniformly coats the surface of the composite oxide to obtain the nanoscale metal oxide catalyst.

[0008] The solid suspension stabilizer is polyvinyl alcohol or modified polyvinylpyrrolidone.

[0009] Further, the treatment process of the plasma-activated fly ash is as follows: the fly ash is collected in a dust-free environment, and after screening to remove large impurities, the fly ash is placed in a plasma reactor, oxygen is introduced, the oxygen flow is 10-50L / min, the power of the plasma generator is adjusted to 500-1500W, and the fly ash is treated at 800-1200℃ for 1-2h, and then naturally cooled to room temperature.

[0010] Further, the preparation process of the metal-organic framework functionalized organic ligand ZIF-8 type MOF is as follows: zinc nitrate as a metal salt and 2-methylimidazole as an organic ligand are accurately weighed and placed in a reaction bottle, the molar ratio between zinc ions and 2-methylimidazole is 1:2, deionized water is added to adjust the pH to 3-6, and the hydrothermal synthesis reaction is carried out in a constant temperature water bath at 80-120℃ for 12-48h, and then the MOF material is obtained by natural cooling and centrifugal separation, the MOF material is washed with anhydrous ethanol for 3-5 times and vacuum dried at 60-80℃ for 12-24h.

[0011] Preferably, the molar ratio among the calcium oxide, magnesium oxide and zinc oxide is 1:(0.5-1.5):(0.3-1), the ball-milling and mixing is performed for 2-4h, the calcination temperature is 800-900℃, the calcination time is 2-4h, the ultrasonic dispersion is performed for 1-3h, and the concentration of the graphene dispersion liquid is 5-15mg / mL.

[0012] Preferably, the mass ratio between the acrylic acid and the acrylamide in the poly(acrylic acid-co-acrylamide) copolymer is 1:(0.8-1.2), and the molecular weight of the poly(acrylic acid-co-acrylamide) copolymer is 50-100w.

[0013] Preferably, the molecular weight of the polyvinyl alcohol is 10-300 million; the modification process of the modified polyvinylpyrrolidone is that, under the action of an initiator, a chemical crosslinking reaction occurs between the polyvinylpyrrolidone and divinylbenzene as a crosslinking agent, and the crosslinking degree is controlled at 5%-15%

[0014] To achieve the above-mentioned purpose, the application further provides a preparation method of the multifunctional composite material based on fly ash mineralization CO2 storage.

[0015] S1, the plasma-activated fly ash, nanoscale metal oxide catalyst, metal organic framework functional organic ligand ZIF-8 type MOF and high-purity water are stirred and mixed in proportion, and a solid suspension stabilizer is added during stirring to form a suspension, and the stirring time is 30-60 min;

[0016] S2, the suspension is placed in a high-pressure reaction kettle, the reaction temperature is controlled at 40-80 DEG C, the pressure is 5-10 MPa, CO2 gas is introduced under ultrasonic conditions, and the mineralization reaction is carried out for 2-6 h; during the mineralization process, the pH value of the reaction environment is dynamically regulated to 7-9 by using an intelligent pH regulator poly(acrylic acid-co-acrylamide) copolymer;

[0017] S3, the reaction liquid obtained in step S2 is centrifuged at a speed of 3000-5000 rpm for 30-60 min, the mineralization product is separated from the suspension at high speed, and then the precipitate is placed in a freeze dryer and dried at-40 DEG C to-20 DEG C for 12-24 h to obtain superfine nanoscale carbonate solid material, i.e. multifunctional composite material.

[0018] Preferably, in step S2, the temperature is controlled in stages, the reaction temperature is controlled at 60-80 DEG C at the beginning of the reaction, and the reaction is carried out for 1-3 h; then the temperature is lowered to 40-50 DEG C, and the reaction is carried out for 1-3 h.

[0019] Further, in step S2, a poly(acrylic acid-co-acrylamide) copolymer aqueous solution with a mass concentration of 5%-10% is prepared as an intelligent pH regulator, and the intelligent pH regulator is added before the suspension is added to the high-pressure reaction kettle.

[0020] Preferably, in step S2, the ultrasonic oscillation frequency is 20-40 kHz; the CO2 gas flow rate is 10-50 mL / min.

[0021] Compared with the prior art, the composite material prepared by the application has the following advantages:

[0022] (1) High-efficiency CO2 capture and mineralization ability: The nanoscale metal oxide catalyst in the present application can improve the electrical conductivity and surface activity of the catalyst, thereby significantly improving the mineralization efficiency of CO2; the functional organic ligand of the metal organic framework uses metal organic framework (MOF) material with three-dimensional porous structure to enhance its adsorption capacity and selectivity for CO2 molecules; the present application significantly improves the CO2 capture ability and mineralization reaction rate through the synergistic effect of the nanoscale metal oxide catalyst and the functional organic ligand of the metal organic framework, thereby realizing high-efficiency CO2 sequestration.

[0023] (2) Excellent chemical stability: The mineralization product of the present application is a nanoscale carbonate microparticle, the main components of which are calcium carbonate and magnesium carbonate, the purity of which is not less than 95%, the particle size range of which is 10-100 nanometers, which has high crystallinity, high specific surface area and excellent chemical stability, and can withstand a large range of temperature changes and acid-base environment, and is suitable for high-end building materials, energy storage materials and environmental remediation fields.

[0024] (3) Green and environmentally friendly: The present application uses industrial by-product fly ash as the main raw material, realizes the resource utilization of waste, and reduces environmental pollution and resource waste.

[0025] Compared with the prior art, the preparation method of the present application has the following advantages:

[0026] (1) Plasma activation treatment: The fly ash of the present application is treated by high-temperature plasma, which enhances the surface activity of the fly ash and improves its reaction ability with CO2, thereby optimizing the kinetic performance of the mineralization reaction;

[0027] (2) Ultrasonic enhancement technology: The present application uses ultrasonic oscillation in the mineralization reaction process, which improves the contact efficiency of CO2 and fly ash particles and further accelerates the mineralization reaction;

[0028] (3) Graded temperature control strategy: The present application adopts a graded temperature control strategy in the mineralization reaction process, maintaining a high temperature in the early stage to accelerate CO2 absorption, and reducing the temperature in the later stage to ensure the high purity and crystal integrity of the mineralization product;

[0029] (4) Intelligent pH adjustment technology: The intelligent pH adjuster in the present application is a high molecular material poly(acrylic acid-co-acrylamide) copolymer with self-adaptive response ability, which can dynamically adjust the solution pH to the optimal range according to the CO2 concentration change in the reaction process, ensuring the reaction stability and optimal mineralization conditions, and maximizing the mineralization efficiency;

[0030] (5) High-efficiency separation and drying technology: The present application uses high-speed centrifugal separation technology and freeze-drying technology to effectively separate the mineralization product and preserve the structure and chemical properties of the product, thereby improving the stability of the mineralization product.

[0031] In summary, the present application significantly improves the capture and mineralization efficiency of carbon dioxide (CO2) by introducing nanoscale metal oxide catalysts, metal organic framework functionalized organic ligands, plasma activation treatment, ultrasonic enhancement technology and intelligent control technology, significantly improves the CO2 storage efficiency, and meets the requirements of industrial application; the reaction conditions are optimized to generate high value-added stable carbonate products, further realizing the resource utilization of industrial by-products fly ash, achieving the dual goals of reducing carbon emissions and improving solid waste utilization rate. The present application has the characteristics of high efficiency, green environmental protection, simple preparation method, low material cost, significantly improved storage efficiency, etc., and is suitable for large-scale industrial application in carbon capture and storage (CCS) technology. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 A comparison chart of mechanical properties of the multifunctional composite material prepared by the present application and ordinary building materials is shown in the figure.

[0033] Figure 2 The adsorption-desorption isotherm chart of the multifunctional composite material prepared by the present application is shown in the figure. DETAILED DESCRIPTION

[0034] The present application will be further described in detail below in combination with the drawings and specific examples.

[0035] Example 1

[0036] A multifunctional composite material for mineralization and storage of CO2 based on fly ash, which is composed of the following raw materials by mass weight parts: plasma-activated fly ash 80 parts, nanoscale metal oxide catalyst 5 parts, metal organic framework functionalized organic ligand ZIF-8 type MOF 8 parts, intelligent pH regulator poly(acrylic acid-co-acrylamide) copolymer 1.5 parts, solid suspension stabilizer 4 parts, high-purity water 15 parts.

[0037] The plasma-activated fly ash contains 60wt% of SiO2, 25wt% of Al2O3, 10wt% of CaO and 5wt% of unavoidable impurities;

[0038] Fly ash is treated by high-temperature plasma to improve its surface activity and reaction capacity. During the treatment, oxygen plasma reacts with metal oxides in the fly ash, increasing the specific surface area of the fly ash and thus improving its reaction capacity with CO2. The specific treatment process is as follows: collect fly ash in a dust-free environment, remove large impurities by sieving, and then put it into a plasma reactor, introduce oxygen, set the oxygen flow rate to 30 L / min, and adjust the plasma generator power to 1000 W to ensure that the fly ash surface can fully contact the plasma; treat at 1000℃ for 1.5h to maximize the surface activity of the fly ash; after the treatment is completed, take out the fly ash and cool it to room temperature naturally, and prepare for use.

[0039] The preparation process of the nanoscale metal oxide catalyst is as follows: calcium oxide, magnesium oxide and zinc oxide are first mixed in a ball mill at a molar ratio of 1:1:0.5 for 3h to obtain a mixed powder, which is calcined at 850℃ for 3h under nitrogen protection to obtain a composite oxide, which is then placed in a graphene dispersion solution with a concentration of 10mg / mL, and ultrasonic dispersion is performed for 2h to uniformly coat the graphene on the surface of the composite oxide, and the uncoated graphene is separated by centrifugation to obtain the nanoscale metal oxide catalyst;

[0040] The preparation process of the metal-organic framework functionalized organic ligand ZIF-8 type MOF is as follows: accurately weigh zinc nitrate as a metal salt and 2-methylimidazole as an organic ligand into a reaction bottle, the molar ratio between zinc ions and 2-methylimidazole is 1:2, add deionized water to adjust the pH to 4.5, and perform hydrothermal synthesis reaction at 100℃ in a constant temperature water bath for 24h, then naturally cool down, centrifuge to obtain the MOF material, wash the MOF material with anhydrous ethanol 4 times and vacuum dry at 70℃ for 18h;

[0041] The mass ratio between acrylic acid and acrylamide in the intelligent pH regulator poly(acrylic acid-co-acrylamide) copolymer is 1:1, and the molecular weight of the poly(acrylic acid-co-acrylamide) copolymer is 80,000;

[0042] The solid suspension stabilizer is polyvinyl alcohol, and the molecular weight of the polyvinyl alcohol is 200,000.

[0043] The above preparation method of the multifunctional composite material for mineralization and sequestration of CO2 based on fly ash includes the following steps:

[0044] S1, the plasma-activated fly ash, nano metal oxide catalyst, metal organic framework functionalized organic ligand ZIF-8 type MOF and high purity water are added into a container with stirring device in proportion, the stirring is started, the stirring speed is controlled at 400 rpm, the solid suspension stabilizer is added during stirring to ensure the stability of the suspension, the stirring is uniform until the suspension presents uniform state without obvious precipitation and stratification, the stirring time is 45 min; the prepared suspension is filtered, the filter screen with pore size of 50 μm is used to remove possible large particle impurities, and the pure suspension is obtained for standby;

[0045] S2, the suspension is placed in a high-pressure reaction kettle, and a hierarchical temperature control is adopted, the reaction temperature is controlled at 70℃ in the initial stage of reaction, and the reaction is carried out for 2 h; then the temperature is reduced to 45℃, and the reaction is carried out for 2 h; the pressure is 8 MPa, CO2 gas is introduced under ultrasonic condition, the ultrasonic oscillation frequency is set to 30 kHz, the fly ash particles in the suspension are ensured to be in full contact with CO2, the mineralization reaction is promoted, the gas flow is controlled at 30 mL / min, CO2 is fully reacted with the fly ash in the suspension, and the mineralization reaction is carried out for 4 h; during the mineralization process, the intelligent pH regulator poly(acrylic acid-co-acrylamide) copolymer (previously prepared into an aqueous solution with a mass concentration of 8%, and added into the suspension before the suspension is added into the high-pressure reaction kettle) is used to dynamically control the pH value of the reaction environment to be 8, so as to maximize the mineralization efficiency;

[0046] S3, the reaction liquid obtained in step S2 is centrifuged at a speed of 4000 rpm for 45 min, the mineralization product is separated from the suspension at high speed, then the precipitate is placed in a freeze dryer and dried at-30℃ for 18 h to ensure that the moisture in the precipitate is completely removed, freeze drying can effectively preserve the structure and chemical properties of the product and improve the stability of the mineralization product, and finally the stable ultrafine nano carbonate solid material, i.e. multifunctional composite material, is obtained.

[0047] The mechanical properties of the nano carbonate solid material prepared in this embodiment and ordinary building materials in terms of compressive strength and flexural strength are compared as shown in the table. Figure 1 As can be seen from the table, Figure 1 the compressive strength of the nano carbonate solid material is close to 32 MPa, and the flexural strength is about 6 MPa. In contrast, the compressive strength of ordinary building materials is about 15 MPa, and the flexural strength is relatively low, only about 3.5 MPa. Therefore, the nano carbonate solid material is significantly superior to ordinary building materials in terms of compressive strength and flexural strength, especially in terms of compressive strength. This comparison highlights the higher application value of the nano carbonate solid material in the field of building.

[0048] The adsorption and desorption curves of the nanoscale carbonate solid material prepared in this embodiment in nitrogen are shown in Figure 2 From the Figure 2 It can be seen from the adsorption curve that the adsorption amount rises rapidly at low relative pressure and then slows down, indicating that the material has many active sites on the surface, and micropores preferentially adsorb nitrogen at low pressure, and mesopores and macropores gradually participate in adsorption and approach saturation as the pressure rises. The desorption amount decreases as the pressure decreases, and the adsorbed nitrogen is easy to desorb at high pressure and difficult to desorb at low pressure. The adsorption and desorption curves do not coincide to form a hysteresis loop, reflecting the complex pore structure and different pore size distribution of the material. The adsorption amount of the material is as high as 270 cm 3 / g, indicating that the material has strong adsorption performance. This advantage can make the material play an important role in the field of carbon dioxide mineralization and sequestration.

[0049] Example 2

[0050] A multifunctional composite material for mineralization and sequestration of CO2 based on fly ash, which is composed of the following raw materials by mass weight parts: plasma-activated fly ash 70 parts, nanoscale metal oxide catalyst 3 parts, metal-organic framework functionalized organic ligand ZIF-8 type MOF 5 parts, intelligent pH regulator poly(acrylic acid-co-acrylamide) copolymer 1 part, solid suspension stabilizer 3 parts, high-purity water 10 parts.

[0051] The plasma-activated fly ash contains 50wt% SiO2, 20wt% Al2O3, 15wt% CaO and 15wt% other components.

[0052] The fly ash is treated by high-temperature plasma to improve its surface activity and reaction capacity. During the treatment process, oxygen plasma reacts with metal oxides in the fly ash, increasing the specific surface area of the fly ash and thus improving its reaction capacity with CO2. The specific treatment process is as follows: collect the fly ash in a dust-free environment, remove large impurities by sieving, and then put it into a plasma reactor, introduce oxygen with a flow rate of 10 L / min, adjust the power of the plasma generator to 500 W to ensure that the surface of the fly ash can fully contact the plasma; treat at 800℃ for 1h to maximize the surface activity of the fly ash; after treatment, take out the fly ash and cool it to room temperature naturally, and then use it.

[0053] The preparation process of the nanoscale metal oxide catalyst is as follows: calcium oxide, magnesium oxide and zinc oxide are first mixed in a ball mill at a molar ratio of 1:0.5:0.3 for 2 hours to obtain a mixed powder, the mixed powder is calcined at 800 DEG C for 2 hours under nitrogen protection, and then the composite oxide is naturally cooled to room temperature, and then the composite oxide is placed in a graphene dispersion liquid with a concentration of 5 mg / mL, ultrasonic dispersion is carried out for 1 hour to make the graphene uniformly coated on the surface of the composite oxide, and the uncoated graphene is separated by centrifugal separation, thereby obtaining the nanoscale metal oxide catalyst;

[0054] The preparation process of the metal-organic framework functionalized organic ligand ZIF-8 type MOF is as follows: zinc nitrate as a metal salt and 2-methyl imidazole as an organic ligand are accurately weighed and placed in a reaction bottle, the molar ratio between zinc ions and 2-methyl imidazole is 1:2, deionized water is added to adjust the pH to 3, and the hydrothermal synthesis reaction is carried out at 80 DEG C in a constant temperature water bath for 12 hours, and then the reaction is naturally quenched and cooled, and the MOF material is obtained by centrifugal separation, and the MOF material is washed with anhydrous ethanol for 3 times and vacuum dried at 60 DEG C for 12 hours;

[0055] The mass ratio between acrylic acid and acrylamide in the intelligent pH regulator poly(acrylic acid-co-acrylamide) copolymer is 1:0.8, and the molecular weight of the poly(acrylic acid-co-acrylamide) copolymer is 50,000;

[0056] The solid suspension stabilizer is modified polyvinylpyrrolidone, and the modification process of the modified polyvinylpyrrolidone is as follows: divinylbenzene is used as a crosslinking agent, and a chemical crosslinking reaction occurs between the polyvinylpyrrolidone and the initiator under the action of the initiator, and the crosslinking degree is controlled at 5%.

[0057] The preparation method of the multifunctional composite material based on fly ash mineralization sequestration of CO2 includes the following steps:

[0058] S1, the plasma-activated fly ash, nanoscale metal oxide catalyst, metal-organic framework functionalized organic ligand ZIF-8 type MOF and high-purity water are added to a container with a stirring device in proportion, and stirring is started, and a solid suspension stabilizer is added during stirring to ensure the stability of the suspension, and the stirring is uniform until the suspension presents a uniform and consistent state without obvious precipitation and stratification, and the stirring time is 30 minutes; the prepared snapshot suspension is filtered to remove possible large particle impurities, and a pure suspension is obtained for standby use;

[0059] S2, the suspension is placed in a high-pressure reaction kettle, and a staged temperature control is adopted; the reaction temperature is controlled to be 60 DEG C in the initial stage of the reaction; the temperature is lowered to 40 DEG C after 1 h; the pressure is 5 MPa; CO2 gas is introduced under ultrasonic conditions; the ultrasonic oscillation frequency is set to be 20 kHz; the powder fly ash particles in the suspension are ensured to be in full contact with CO2, so that the mineralization reaction is promoted; the gas flow is controlled to be 10 mL / min; CO2 is fully reacted with the powder fly ash in the suspension; the mineralization reaction is carried out for 2 h; during the mineralization process, the pH value of the reaction environment is dynamically regulated to be 7 by using the intelligent pH regulator poly(acrylic acid-co-acrylamide) copolymer, so that the mineralization efficiency is maximized;

[0060] S3, the reaction liquid obtained in step S2 is centrifuged at a speed of 3000 rpm for 30 min; the mineralization product is separated from the suspension at high speed; then the precipitate is placed in a freeze dryer and dried at-40 DEG C for 12 h, so that the moisture in the precipitate is completely removed; the freeze drying can effectively preserve the structure and chemical properties of the product, and improve the stability of the mineralization product; finally, the stable ultrafine nanoscale carbonate solid material, i.e., the multifunctional composite material, is obtained.

[0061] The composite material prepared in the embodiment is proved to be significantly superior to ordinary building materials in terms of compressive strength and bending strength, especially in terms of compressive strength, by experiments. Therefore, the composite material prepared by the application has higher application value in the field of building.

[0062] In addition, the composite material prepared in the embodiment is subjected to adsorption and desorption experiments, and the experimental process is consistent with the embodiment, and the experimental results are similar to those of the embodiment. The adsorption capacity of the material is as high as 260 cm 3 / g, which indicates that the material has strong adsorption performance. Such an advantage can make the material play an important role in the field of CO2 mineralization and storage.

[0063] Example 3

[0064] A multifunctional composite material based on fly ash for mineralization and storage of CO2 is prepared from the following raw materials by mass: plasma-activated fly ash 85 parts, nanoscale metal oxide catalyst 7 parts, metal-organic framework functionalized organic ligand ZIF-8 type MOF 10 parts, intelligent pH regulator poly(acrylic acid-co-acrylamide) copolymer 2 parts, solid suspension stabilizer 5 parts, and high-purity water 20 parts.

[0065] The plasma-activated fly ash contains 65 wt% of SiO2, 20 wt% of Al2O3, 5 wt% of CaO, and 10 wt% of other components;

[0066] Fly ash is treated by high-temperature plasma to improve its surface activity and reaction capacity. During the treatment, oxygen plasma reacts with metal oxides in the fly ash, increasing the specific surface area of the fly ash and thus improving its reaction capacity with CO2. The specific treatment process is as follows: collect fly ash in a dust-free environment, remove large impurities by sieving, and then put it into a plasma reactor. Oxygen is introduced at a flow rate of 50 L / min, and the power of the plasma generator is adjusted to 1500 W to ensure that the surface of the fly ash can fully contact the plasma. The fly ash is treated at 1200℃ for 2h to ensure the maximum surface activity of the fly ash. After the treatment is completed, the fly ash is taken out and naturally cooled to room temperature for standby use.

[0067] The preparation process of the nanoscale metal oxide catalyst is as follows: calcium oxide, magnesium oxide, and zinc oxide are first mixed in a ball mill at a molar ratio of 1:1.5:1 for 4h to obtain a mixed powder. The mixed powder is calcined at 900℃ for 4h under nitrogen protection to obtain a composite oxide. After natural cooling to room temperature, the composite oxide is placed in a graphene dispersion solution with a concentration of 15mg / mL, and ultrasonic dispersion is performed for 3h to uniformly coat the graphene on the surface of the composite oxide. Centrifugal separation is performed to remove the uncoated graphene, and the nanoscale metal oxide catalyst is obtained.

[0068] The preparation process of the metal-organic framework functionalized organic ligand ZIF-8 type MOF is as follows: zinc nitrate as a metal salt and 2-methylimidazole as an organic ligand are accurately weighed and placed in a reaction bottle. The molar ratio of zinc ions to 2-methylimidazole is 1:2. Deionized water is added to adjust the pH to 6. The hydrothermal synthesis reaction is carried out at 120℃ in a constant-temperature water bath for 48h. After the reaction is completed, natural cooling is performed, and centrifugal separation is performed to obtain the MOF material. The MOF material is washed with anhydrous ethanol for 5 times and vacuum dried at 80℃ for 24h.

[0069] The mass ratio of acrylic acid to acrylamide in the intelligent pH regulator poly(acrylic acid-co-acrylamide) copolymer is 1:1.2, and the molecular weight of the poly(acrylic acid-co-acrylamide) copolymer is 100,000.

[0070] The solid suspension stabilizer is modified polyvinylpyrrolidone. The modification process of the modified polyvinylpyrrolidone is as follows: divinylbenzene is used as a crosslinking agent, and a chemical crosslinking reaction occurs between the polyvinylpyrrolidone and the initiator under the action of the initiator. The crosslinking degree is controlled at 15%.

[0071] The preparation method of the multifunctional composite material based on fly ash mineralization for CO2 sequestration includes the following steps:

[0072] S1, the plasma-activated fly ash, nano metal oxide catalyst, metal organic framework functionalized organic ligand ZIF-8 type MOF and high purity water are added into a container with stirring device in proportion, the stirring is started, the solid suspension stabilizer is added in the stirring process to ensure the stability of the suspension, the stirring is uniform until the suspension presents uniform state without obvious precipitation and stratification phenomenon, the stirring time is 60 min; the prepared suspension is filtered to remove possible large particle impurities to obtain pure suspension for standby;

[0073] S2, the suspension is placed in a high-pressure reaction kettle, a hierarchical temperature control is adopted, the reaction temperature is controlled to be 80 DEG C in the initial stage of reaction, the reaction is carried out for 3 h; then the temperature is reduced to 50 DEG C, and the reaction is carried out for 3 h; the pressure is 10 MPa, CO2 gas is introduced under ultrasonic condition, the ultrasonic oscillation frequency is set to 40 kHz, the fly ash particles in the suspension are ensured to be fully contacted with CO2 to promote the progress of mineralization reaction, the gas flow is controlled to be 50 mL / min, CO2 is fully reacted with fly ash in the suspension to carry out mineralization reaction for 6 h; in the mineralization process, the intelligent pH regulator poly (acrylic acid-co-acrylamide) copolymer is used to dynamically control the pH value of the reaction environment to be 9 to maximize the mineralization efficiency;

[0074] S3, the reaction liquid obtained in step S2 is centrifuged at a speed of 5000 rpm for 60 min, the mineralization product is separated from the suspension at high speed, then the precipitate is placed in a freeze dryer and dried at-20 DEG C for 24 h to ensure that the moisture in the precipitate is completely removed, freeze drying can effectively preserve the structure and chemical properties of the product and improve the stability of the mineralization product, finally the stable ultrafine nano carbonate solid material, i.e. multifunctional composite material, is obtained.

[0075] The composite material prepared in the embodiment is proved to be significantly better than ordinary building materials in compression and bending strength, especially in compression strength, through experiments, and the experimental process is consistent with the embodiment.

[0076] In addition, the composite material prepared in the embodiment is subjected to adsorption and desorption experiments, the experimental process is consistent with the embodiment, and the experimental results are similar to those of the embodiment. 3 The adsorption capacity of the material is as high as 280 cm / g, which indicates that the material has strong adsorption performance. This advantage can make the material play an important role in carbon dioxide mineralization and storage and other fields.

Claims

1. A multifunctional composite material for CO2 storage based on fly ash mineralization, characterized in that: The invention is composed of the following raw materials in parts by weight: 70-85 parts of fly ash treated with plasma activation, 3-7 parts of nano-scale metal oxide catalyst, 5-10 parts of metal organic framework functionalized organic ligand ZIF-8 type MOF, 1-2 parts of smart pH regulator poly(acrylic acid-co-acrylamide) copolymer, 3-5 parts of solid suspension stabilizer, and 10-20 parts of high-purity water; The fly ash treated by plasma activation contains 50-65wt% SiO2, 20-30wt% Al2O3, 5-15wt% CaO, and the remaining components are inevitable impurities; The preparation process of the nano-scale metal oxide catalyst comprises: weighing calcium oxide, magnesium oxide, and zinc oxide in order according to a ratio, ball-milling and mixing to obtain a mixed powder, calcining at a high temperature to form a composite oxide, and then placing the composite oxide in a graphene dispersion liquid, ultrasonically dispersing the composite oxide, and uniformly coating the graphene on the surface of the composite oxide to obtain the nano-scale metal oxide catalyst; The solid suspension stabilizer is polyvinyl alcohol or modified polyvinyl pyrrolidone.

2. The multifunctional composite material for CO2 storage based on fly ash mineralization according to claim 1, characterized in that: The treatment process of the fly ash treated with plasma activation is as follows: the fly ash is collected in a dust-free environment, sieved to remove large impurities, placed in a plasma reactor, oxygen is introduced at an oxygen flow rate of 10-50 L / min, the plasma generator power is adjusted to 500-1500 W, the fly ash is treated at 800-1200° C. for 1-2 hours, and then naturally cooled to room temperature.

3. A multifunctional composite material for CO2 storage based on fly ash mineralization according to claim 1 or 2, characterized in that: The preparation process of the metal-organic framework functionalized organic ligand ZIF-8 type MOF is as follows: zinc nitrate as a metal salt and 2-methylimidazole as an organic ligand are accurately weighed and placed in a reaction bottle, with the molar ratio of zinc ion to 2-methylimidazole being 1:2; deionized water is added to adjust the pH to 3-6; a hydrothermal synthesis reaction is carried out in a constant temperature water bath at 80-120° C. for 12-48 hours; after the reaction is completed, the mixture is naturally cooled and centrifuged to obtain a MOF material; the MOF material is washed with anhydrous ethanol 3-5 times and vacuum dried at 60-80° C. for 12-24 hours.

4. A multifunctional composite material for CO2 storage based on fly ash mineralization according to claim 1 or 2, characterized in that: The molar ratio of calcium oxide, magnesium oxide and zinc oxide is 1: (0.5-1.5): (0.3-1); ball milling mixing is performed for 2-4 hours; the calcination temperature is 800-900° C. and the calcination time is 2-4 hours; ultrasonic dispersion is performed for 1-3 hours; and the concentration of the graphene dispersion is 5-15 mg / mL.

5. A multifunctional composite material for CO2 storage based on fly ash mineralization according to claim 1 or 2, characterized in that: The mass ratio of acrylic acid to acrylamide in the poly(acrylic acid-co-acrylamide) copolymer is 1:(0.8-1.2), and the molecular weight of the poly(acrylic acid-co-acrylamide) copolymer is 50,000-100,000.

6. A multifunctional composite material for CO2 storage based on fly ash mineralization according to claim 1 or 2, characterized in that: The molecular weight of the polyvinyl alcohol is 100,000-300,000. The modification process of the modified polyvinyl pyrrolidone is as follows: divinylbenzene is used as a crosslinking agent, and a chemical crosslinking reaction occurs with the polyvinyl pyrrolidone under the action of an initiator, and the crosslinking degree is controlled at 5%-15%.

7. A method for preparing a multifunctional composite material for CO2 storage based on fly ash mineralization according to claim 1, characterized in that: The steps include: S1. Mix fly ash treated with plasma activation, nano-sized metal oxide catalyst, metal organic framework functionalized organic ligand ZIF-8 type MOF, and high-purity water in proportion, add a solid suspension stabilizer during the stirring process, and stir evenly to form a suspension. The stirring time is 30-60 minutes; S2. Placing the suspension in a high-pressure reactor, controlling the reaction temperature to 40-80°C and the pressure to 5-10 MPa, introducing CO2 gas under ultrasonic conditions, and conducting a mineralization reaction for 2-6 hours; during the mineralization process, using an intelligent pH regulator poly(acrylic acid-co-acrylamide) copolymer to dynamically control the pH value of the reaction environment to 7-9; S3. Centrifuge the reaction solution obtained in step S2 at a speed of 3000-5000 rpm for 30-60 minutes to separate the mineralized product from the suspension by high-speed centrifugation. Then, place the precipitate in a freeze dryer and dry it at -40°C to -20°C for 12-24 hours to obtain an ultrafine nano-scale carbonate solid material, i.e., a multifunctional composite material.

8. The method for preparing a multifunctional composite material for CO2 storage based on fly ash mineralization according to claim 7, characterized in that: In step S2, graded temperature control is adopted. In the initial stage of the reaction, the reaction temperature is controlled at 60-80°C and the reaction is carried out for 1-3 hours; then the temperature is lowered to 40-50°C and the reaction is carried out for 1-3 hours.

9. The method for preparing a multifunctional composite material for CO2 storage based on fly ash mineralization according to claim 7 or 8, characterized in that: In step S2, a poly(acrylic acid-co-acrylamide) copolymer aqueous solution with a mass concentration of 5%-10% is prepared in advance as an intelligent pH regulator, and the intelligent pH regulator is added before the suspension is added to the autoclave.

10. The method for preparing a multifunctional composite material for CO2 storage based on fly ash mineralization according to claim 7 or 8, characterized in that: In step S2, the ultrasonic oscillation frequency is 20-40 kHz; the CO2 gas flow rate is 10-50 mL / min.

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