A kind of air entraining agent capable of selectively adsorbing carbon dioxide and a preparation method thereof

Abstract

The application discloses a kind of carbon dioxide selectively adsorbed air entraining agent and preparation method, including the following raw materials: carbon dioxide adsorption functional group, crosslinking agent, rosin-based air entraining agent, catalyst and water.The carbon dioxide selectively adsorbed air entraining agent provided in the application guarantees good air entraining performance while improving the proportion of carbon dioxide in the introduced gas, providing a new way and method for the preparation of carbon capture concrete.The air entraining agent can be well compounded with the water reducing agent on the market, is easy and fast to use, and has a wide application field due to good air entraining effect, such as highways, bridges, reservoirs, dams and other engineering, and is also suitable for structural engineering with high requirements for frost resistance and durability, such as highways and bridge engineering in the northern cold region.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, and in particular relates to an air-entraining agent that can selectively adsorb carbon dioxide and its preparation method. Background Technology

[0002] With the introduction of the "dual carbon" target, the low-carbon and greening of cement concrete, the most widely used basic material, has received increasing attention. The carbon dioxide released during cement production accounts for 8% of global anthropogenic carbon dioxide emissions. To address the high carbon dioxide emissions from cement concrete, researchers have begun exploring the feasibility of using concrete as a "vessel" to solidify carbon dioxide. Studies have found that carbon dioxide can undergo a carbonization reaction with calcium hydroxide, hydrated calcium silicate gel, and cement clinker in cement-based materials, thereby reducing the amount of carbon dioxide released during cement preparation.

[0003] Air-entraining agents, acting as surfactants, significantly reduce the surface tension and interfacial energy of water, promoting the generation of tiny, closed air bubbles in the aqueous solution during stirring. These agents enhance the freeze-thaw resistance and workability of concrete by increasing its air content. Besides containing hydration products that can chemically react with carbon dioxide, the closed pores of concrete also serve as "vessels" for solidifying carbon dioxide. Common concrete has a porosity of 1%–5% and an air content typically of 3.5%–6%. Sealing carbon dioxide within the closed pores of concrete increases its carbon absorption capacity, improves operability, eliminates the need for carbonation treatment of raw materials or specimens, reduces the cost of preparing carbon-capturing concrete, and simplifies the preparation process.

[0004] Existing patents related to air-entraining agents, such as CN201810515600.X and CN202010735672.2, mostly focus on improving the pore structure of concrete and increasing air-entraining efficiency. However, research on carbon-fixing air-entraining agents specifically designed for carbon dioxide absorption by the pore structure of concrete is relatively limited. Therefore, in order to utilize air-entraining agents to increase the carbon dioxide content in the introduced gas and achieve large-scale carbon fixation in the concrete industry, research on carbon dioxide adsorption air-entraining agents is urgently needed. Summary of the Invention

[0005] In view of this, the present invention provides an air-entraining agent that can selectively adsorb carbon dioxide and a preparation method thereof, with the aim of increasing the proportion of carbon dioxide gas introduced into the pores of concrete, and providing a new idea and approach for the preparation of carbon capture concrete.

[0006] To achieve the above objectives, the following technical solution is adopted:

[0007] An air-entraining agent capable of selectively adsorbing carbon dioxide, comprising the following raw materials:

[0008] Carbon dioxide adsorption functional groups, crosslinking agents, rosin-based air-entraining agents, catalysts, and water.

[0009] The raw materials, by mass percentage, are:

[0010] Carbon dioxide adsorption functional groups: 5%–30%

[0011] Crosslinking agent: 2%–8%

[0012] Rosin-based air-entraining agent: 50%–80%

[0013] Catalyst: 0.5%–2.0%

[0014] Water: 10%–40%.

[0015] The carbon dioxide adsorption functional group is one or a mixture of several of polyethylene glycol-carboxyl, hydroxyacetamide, and maleic acid.

[0016] The crosslinking agent is one or a mixture of several of the following: two-arm polyethylene glycol-carboxyl, three-arm polyethylene glycol-carboxyl, and four-arm polyethylene glycol-carboxyl.

[0017] The rosin-based air-entraining agent is one or a mixture of several of the following: rosin acid, rosin saponification air-entraining agent, and rosin thermal polymer.

[0018] The catalyst is one of the following: concentrated sulfuric acid or a catalytic system composed of dicyclohexylcarbodiimide and 4-dimethylaminopyridine.

[0019] The preparation process of the above-mentioned selective carbon dioxide adsorption agent includes the following steps:

[0020] After heating the rosin-based air-entraining agent to temperature T1, a catalyst is added, and heating is stopped. After cooling to the reaction temperature T2, a crosslinking agent is added, followed by the addition of carbon dioxide adsorption functional groups to carry out the reaction. After the reaction is completed, the temperature is cooled to T3, and deionized water is added to obtain an air-entraining agent that can selectively adsorb carbon dioxide.

[0021] The role of the catalyst is to lower the reaction barrier of the esterification reaction, thereby reducing the occurrence temperature.

[0022] The purpose of heating to temperature T1 is to bring the rosin-based air-entraining agent into a molten state.

[0023] The purpose of cooling down to temperature T2 is to regulate the rate of esterification reaction between the crosslinking agent and the air-entraining agent.

[0024] The purpose of cooling to temperature T3 is to completely dissolve the reaction product, the air-entraining agent, while avoiding evaporation after the addition of deionized water.

[0025] The heating and melting temperature T1 of the rosin-based air-entraining agent is 120℃~140℃.

[0026] The reaction temperature T2 is 90℃~120℃, and the reaction time is 3~8h.

[0027] After the reaction is complete, cool down to temperature T3 of 80°C and add deionized water.

[0028] By employing the above technical solution, the selective carbon dioxide adsorption gas-entraining agent proposed in this invention has at least the following advantages:

[0029] 1. The method for preparing the selective carbon dioxide adsorbent proposed in this invention is simple and ensures good air entrainment performance while increasing the proportion of carbon dioxide in the introduced gas, so that the carbon dioxide is solidified in the pores of concrete, providing a new approach and method for the preparation of carbon capture concrete.

[0030] 2. The selective carbon dioxide adsorption air-entraining agent proposed in this invention exhibits better water solubility. Rosin soap-based air-entraining agents obtain a hydrophilic functional group through the saponification reaction of rosin acid and alkali, resulting in generally poor water solubility. In contrast, the carbon dioxide functional groups introduced in the air-entraining agent of this invention exhibit good hydrophilicity. They can form hydrogen bonds with water molecules in the aqueous phase, increasing the solubility of the air-entraining agent in aqueous solution.

[0031] 3. The selective carbon dioxide adsorption air-entraining agent proposed in this invention simplifies the preparation process of carbon capture concrete and reduces the preparation cost of carbon capture concrete.

[0032] 4. The selective carbon dioxide adsorption air-entraining agent proposed in this invention has been tested and found to be well-blended with water-reducing agents currently on the market. It is easy and quick to use, and its good air-entraining effect makes its application fields wider, such as highway, bridge, reservoir, dam and other projects. It is also suitable for structural engineering with high requirements for frost resistance and durability, such as highway and bridge projects in cold northern regions. Detailed Implementation

[0033] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below.

[0034] An air-entraining agent capable of selectively adsorbing carbon dioxide according to the present invention comprises the following raw materials:

[0035] Carbon dioxide adsorption functional groups, crosslinking agents, rosin-based air-entraining agents, catalysts, and water.

[0036] The raw materials, by mass percentage, are:

[0037] Carbon dioxide adsorption functional groups: 5%–30%

[0038] Crosslinking agent: 2%–8%

[0039] Rosin-based air-entraining agent: 50%–80%

[0040] Catalyst: 0.5%–2.0%

[0041] Water: 10%–40%.

[0042] The carbon dioxide adsorption functional group is one or a mixture of several of polyethylene glycol-carboxyl groups, hydroxyacetamide, and maleic acid. The function of this carbon dioxide adsorption functional group is to attach to the hydrophobic end of the rosin-based air-entraining agent, selectively adsorbing CO2 from the air and increasing the proportion of CO2 in the introduced gas.

[0043] The crosslinking agent is one or a mixture of several of the following: two-arm polyethylene glycol-carboxyl, three-arm polyethylene glycol-carboxyl, and four-arm polyethylene glycol-carboxyl. The polyethylene glycol-carboxyl group and its derivatives have a molecular weight of 500 g / mol to 1500 g / mol. The functions of the crosslinking agent are: ① Through esterification with small rosin molecules, multiple small rosin-based air-entraining agents are linked to form a network structure, thereby increasing the contact area with CO2 in the air and increasing the CO2 content introduced into the concrete; ② Utilizing the alkaline environment of the concrete, the formed ester bonds are hydrolyzed and the network structure is destroyed, refining the size of the air bubbles introduced into the concrete; ③ Selectively adsorbing CO2 from the air.

[0044] The rosin-based air-entraining agent is one or a mixture of several of rosin acid, rosin saponification air-entraining agents, and rosin thermal polymers. The function of the rosin-based air-entraining agent is to significantly reduce the surface tension of the liquid, causing the concrete to generate a large number of microbubbles during the mixing process.

[0045] The catalyst is one of the following: concentrated sulfuric acid or a catalytic system composed of dicyclohexylcarbodiimide and 4-dimethylaminopyridine. The catalyst functions to: ① lower the activation energy of the esterification reaction between rosin-based air-entraining agents and carbon dioxide-loving functional groups, and increase the branching rate of carbon dioxide-loving functional groups; ② promote the formation of network structures by different rosin-based air-entraining agent molecules; ③ lower the esterification reaction temperature.

[0046] The preparation process of the above-mentioned selective carbon dioxide adsorption agent includes the following steps:

[0047] After heating the rosin-based air-entraining agent to temperature T1, a catalyst is added, and heating is stopped. After cooling to the reaction temperature T2, a crosslinking agent is added, followed by the addition of carbon dioxide adsorption functional groups to carry out the reaction. After the reaction is completed, the temperature is cooled to T3, and deionized water is added to obtain an air-entraining agent that can selectively adsorb carbon dioxide.

[0048] The purpose of heating to temperature T1 is to bring the rosin-based air-entraining agent into a molten state.

[0049] The purpose of cooling down to temperature T2 is to regulate the rate of esterification reaction between the crosslinking agent and the air-entraining agent.

[0050] The purpose of cooling to temperature T3 is to completely dissolve the reaction product, the air-entraining agent, while avoiding evaporation after the addition of deionized water.

[0051] The heating and melting temperature T1 of the rosin-based air-entraining agent is 120℃~140℃.

[0052] The reaction temperature T2 is 90℃~120℃, and the reaction time is 3~8h.

[0053] After the reaction is complete, cool down to temperature T3 of 80°C and add deionized water.

[0054] The present invention will be further described below with reference to more specific embodiments, but the present invention is not limited to the embodiments described below.

[0055] Example 1

[0056] First, add 300g of rosin resin to the reactor and heat it to 135℃. When the rosin resin is in a molten state, add 8g of concentrated sulfuric acid to the reactor and stop heating. When the temperature drops to 115℃, add 35g of double-arm polyethylene glycol-carboxyl with a molecular weight of 500g / mol. After reacting for 2 hours, add 15g of hydroxyacetamide. After reacting for 1.5 hours, add 25g of maleic acid and react for 1 hour. After the esterification reaction is completed, cool down to 80℃ and add 180g of deionized water to finally obtain an air-entraining agent that can selectively adsorb carbon dioxide.

[0057] Example 2

[0058] First, 320g of rosin resin was added to the reactor and heated to 140℃. When the rosin resin was in a molten state, 10g of concentrated sulfuric acid was added to the reactor, and the heating was stopped. When the temperature dropped to 118℃, 40g of double-arm polyethylene glycol-carboxyl with a molecular weight of 500g / mol was added. After reacting for 2.5h, 35g of hydroxyacetamide was added. After reacting for 2h, 28g of maleic acid was added. After reacting for 1.5h, the esterification reaction was completed. The temperature was then lowered to 80℃, and 205g of deionized water was added. Finally, an air-entraining agent that can selectively adsorb carbon dioxide was obtained.

[0059] Example 3

[0060] First, 295g of rosin resin was added to the reactor and heated to 135℃. When the rosin resin was in a molten state, 2.5g of dicyclohexylcarbodiimide and 3.2g of 4-dimethylaminopyridine were added to the reactor. Heating was stopped, and when the temperature dropped to 95℃, 15g of double-arm polyethylene glycol-carboxyl with a molecular weight of 500g / mol was added. After reacting for 2.5h, 35g of hydroxyacetamide was added, and after reacting for 1.5h, 22g of maleamic acid was added. After reacting for 2h, the esterification reaction was completed, and the temperature was lowered to 80℃. 130g of deionized water was added, and finally, a gas-entraining agent that can selectively adsorb carbon dioxide was obtained.

[0061] Example 4

[0062] First, 350g of rosin resin was added to the reactor and heated to 140℃. When the rosin resin was in a molten state, 3.5g of dicyclohexylcarbodiimide and 4.2g of 4-dimethylaminopyridine were added to the reactor. Heating was stopped, and when the temperature dropped to 100℃, 35g of three-arm polyethylene glycol-carboxyl with a molecular weight of 1000g / mol was added. After reacting for 2 hours, 25g of hydroxyacetamide was added. After reacting for another 2 hours, 35g of maleic acid was added. After reacting for 1 hour, the esterification reaction was completed. The temperature was then lowered to 80℃, and 200g of deionized water was added to obtain a gas-entraining agent that can selectively adsorb carbon dioxide.

[0063] Example 5

[0064] First, 228g of rosin resin was added to the reaction vessel and heated to 130℃. When the rosin resin was in a molten state, 7g of concentrated sulfuric acid was added to the reaction vessel, and the heating was stopped. When the temperature dropped to 120℃, 35g of four-arm polyethylene glycol-carboxyl with a molecular weight of 800g / mol was added. After reacting for 3 hours, 15g of hydroxyacetamide was added. After reacting for 2 hours, 28g of maleic acid was added. After reacting for 2 hours, the esterification reaction was completed. The temperature was then lowered to 80℃, and 130g of deionized water was added. Finally, an air-entraining agent that can selectively adsorb carbon dioxide was obtained.

[0065] Example 6

[0066] First, 428g of rosin resin was added to the reactor and heated to 140℃. When the rosin resin was in a molten state, 13g of concentrated sulfuric acid was added to the reactor, and the heating was stopped. When the temperature dropped to 120℃, 55g of four-arm polyethylene glycol-carboxyl group with a molecular weight of 1500g / mol was added. After reacting for 2.5h, 55g of hydroxyacetamide was added. After reacting for 2h, 45g of maleic acid was added. After reacting for 2h, the esterification reaction was completed. The temperature was then lowered to 80℃, and 178g of deionized water was added. Finally, a gas-entraining agent that can selectively adsorb carbon dioxide was obtained.

[0067] Example 7

[0068] First, 360g of rosin resin was added to the reactor and heated to 140℃. When the rosin resin was in a molten state, 3.8g of dicyclohexylcarbodiimide and 3.1g of 4-dimethylaminopyridine were added to the reactor. Heating was stopped, and when the temperature dropped to 99℃, 25g of double-arm polyethylene glycol-carboxyl with a molecular weight of 1200g / mol was added. After reacting for 2.4h, 18g of hydroxyacetamide was added. After reacting for 2h, 29g of maleamic acid was added. After reacting for 1.5h, the esterification reaction was completed. The temperature was then lowered to 80℃, and 195g of deionized water was added to obtain a gas-entraining agent that can selectively adsorb carbon dioxide.

[0069] Example 8

[0070] First, 308g of rosin resin was added to the reactor and heated to 135℃. When the rosin resin was in a molten state, 4g of concentrated sulfuric acid was added to the reactor, and the heating was stopped. When the temperature dropped to 120℃, 38g of three-arm polyethylene glycol-carboxyl group with a molecular weight of 1400g / mol was added. After reacting for 2 hours, 25g of hydroxyacetamide was added. After reacting for 2.5 hours, 35g of maleic acid was added. After reacting for 2 hours, the esterification reaction was completed. The temperature was then lowered to 80℃, and 145g of deionized water was added. Finally, an air-entraining agent that can selectively adsorb carbon dioxide was obtained.

[0071] Example 9

[0072] First, 305g of rosin resin was added to the reactor and heated to 135℃. When the rosin resin was in a molten state, 6g of concentrated sulfuric acid was added to the reactor, and the heating was stopped. When the temperature dropped to 120℃, 38g of three-arm polyethylene glycol-carboxyl with a molecular weight of 1400g / mol was added. After reacting for 2.5h, 135g of hydroxyacetamide was added. After the esterification reaction was completed, the temperature was lowered to 80℃, and 134g of deionized water was added. Finally, an air-entraining agent that can selectively adsorb carbon dioxide was obtained.

[0073] The samples (products) synthesized in Examples 1-9 were compared with the performance of rosin-based air-entraining agents currently on the market. The experimental materials used were as follows:

[0074] Cement: This is a reference cement for testing the performance of admixtures, produced by Fushun Cement Co., Ltd. It is a PI-type Portland cement conforming to Appendix A of GB8076-2008 "Concrete Admixtures," with a specific surface area of ​​350 m². 2 / kg;

[0075] Sand: Natural sand, medium sand of Zone II, fineness modulus of 2.92, mud content of 0.6%, conforming to the national standard GB / T14684-2011 "Sand for Construction";

[0076] Gravel: Limestone crushed stone, 5-20mm continuous gradation, mud content ≤0.5%, meeting the requirements of national standard GB / T 14685-2011 "Construction Gravel and Crushed Stone";

[0077] The concrete mix design used to test the air-entraining agent effect is shown in Table 1.

[0078] Table 1

[0079]

[0080] The results of the air content test in concrete are shown in Table 2 below.

[0081] Table 2

[0082]

[0083] As can be seen from the test data in Table 1, the air-entraining agent obtained by this method has a higher air content than traditional rosin-based air-entraining agents under the test conditions, indicating that the air-entraining agent prepared by this method has good air-entraining ability.

[0084] According to GB / T8984-2008 "Determination of carbon monoxide, carbon dioxide and hydrocarbons in gases by gas chromatography", the specific gravity of carbon dioxide in the gas introduced into the samples synthesized in Examples 1 to 9 was tested, and the results are shown in Table 3.

[0085] Table 3

[0086]

[0087]

[0088] As can be seen from the test data in Table 3, the proportion of carbon dioxide introduced into the gas by the gas-entraining agent obtained by this method is significantly increased under the test conditions, indicating that the gas-entraining agent prepared by this method has a strong adsorption capacity for carbon dioxide.

Claims

1. A gas entraining agent that can selectively adsorb carbon dioxide, characterized in that, The raw materials include: carbon dioxide adsorption functional groups, cross-linking agents, rosin-based air entraining agents, catalysts, and water; The raw materials are in mass percentages of: carbon dioxide adsorption functional groups: 5% to 30% cross-linking agents: 2% to 8% rosin-based air entraining agents: 50% to 80% catalysts: 0.5% to 2.0% water: 10% to 40%; The carbon dioxide adsorption functional groups are one or a mixture of several of hydroxyacetamide and maleamic acid; The cross-linking agents are one or a mixture of several of two-armed polyethylene glycol-carboxyl, three-armed polyethylene glycol-carboxyl, and four-armed polyethylene glycol-carboxyl; The catalysts are one of a concentrated sulfuric acid or a catalytic system composed of dicyclohexyl carbodiimide and 4-dimethylamino pyridine; The preparation method of the air entraining agent that can selectively adsorb carbon dioxide is: after heating the rosin-based air entraining agent to a molten state and adding a catalyst, stop heating; after cooling to the reaction temperature, add a cross-linking agent, and then add carbon dioxide adsorption functional groups for reaction; after the reaction is completed, add deionized water to obtain the air entraining agent that can selectively adsorb carbon dioxide.

2. The air entraining agent that can selectively adsorb carbon dioxide according to claim 1, characterized in that: The rosin-based air entraining agent is one or a mixture of several of rosin acid, rosin saponification air entraining agent, and rosin thermal polymer.

3. A preparation method of the air entraining agent that can selectively adsorb carbon dioxide according to claim 1 or 2, characterized in that: comprising: The rosin-based air entraining agent is heated to a molten state and a catalyst is added, heating is stopped; after cooling to the reaction temperature, a cross-linking agent is added, and then carbon dioxide adsorption functional groups are added for reaction; after the reaction is completed, deionized water is added to obtain the air entraining agent that can selectively adsorb carbon dioxide.

4. The preparation method of the air entraining agent that can selectively adsorb carbon dioxide according to claim 3, characterized in that: The heating and melting temperature of the rosin-based air entraining agent is 120°C to 140°C.

5. The preparation method of the air entraining agent that can selectively adsorb carbon dioxide according to claim 3, characterized in that: The reaction temperature is 90°C to 120°C, and the reaction time is 3 to 8 hours.

6. The method of claim 3, wherein the method is characterized by: After the reaction is completed, the temperature is cooled to 80°C, and deionized water is added.

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