A method for absorbing mineralized carbon dioxide using an organic amine

Abstract

This invention discloses a method for absorbing and mineralizing carbon dioxide using organic amines. The main method uses salt lake brine as the mineralization raw material and organic alcoholic amines as carbon dioxide absorbents to fix carbon dioxide and prepare magnesium carbonate trihydrate. This method can produce high-purity magnesium carbonate trihydrate, playing an important role in achieving CO2 emission reduction and protecting the ecological environment of salt lakes. Simultaneously, it facilitates the separation and utilization of magnesium, lithium, and boron resources in salt lakes. This invention utilizes ethanolamine as a carbon dioxide absorbent, which has high absorption efficiency, mineralizing a large amount of magnesium into a homogeneous and stable magnesium carbonate trihydrate product. This can significantly promote the development of carbon neutrality and carbon peaking, and facilitate the efficient utilization of salt lake resources.

Description

Technical Field

[0001] This invention relates to the field of carbon dioxide absorption and mineralization, using salt lake brine as a mineralization raw material and organic amines as an absorbent to fix and convert carbon dioxide. Background Technology

[0002] Carbon capture, utilization, and storage (CCUS) is the process of separating carbon dioxide from industrial processes, energy use, or the atmosphere, and then directly utilizing it or injecting it into geological formations to achieve permanent emission reductions. Integrated carbon dioxide absorption-mineralization technology is a promising post-combustion capture technology. Carbon dioxide captured in organic amine solutions can be directly reacted with calcium and magnesium compounds to form carbonates, thus regenerating the organic amine solution. This utilizes abundant mineral resources on Earth or solid waste from factories to react with carbon dioxide captured from the air or factory flue gas, generating stable inorganic carbonates, achieving carbon dioxide fixation and organic amine regeneration. This method overcomes the low solubility of carbon dioxide in aqueous solutions, accelerates the mineral carbonation rate, and reduces the energy consumption for organic amine solution regeneration.

[0003] With the continuous development of new energy vehicles, lithium extraction from salt lakes has become a research hotspot. The brine after lithium extraction contains a large amount of magnesium, and its return to the salt lake would negatively impact its ecological environment. Utilizing magnesium-rich ammonia-soda wastewater from salt lakes for mineralization and carbon dioxide fixation, converting CO2 into chemicals for carbon recovery and utilization, can significantly reduce carbon emissions and generate economic benefits. Simultaneously, it can achieve efficient utilization and transformation of salt lake resources.

[0004] Magnesium carbonate trihydrate, a mineralized product, has wide applications in industry and daily life. Firstly, it is primarily used in the manufacture of magnesium salts, magnesium oxide, fire-retardant coatings, inks, glass, toothpaste, and rubber fillers. Secondly, it is a raw material for antacids used to treat gastric and duodenal ulcers. Thirdly, it serves as an alkali, desiccant, color-protecting agent, and leavening agent, widely used in the food and chemical industries. Furthermore, the crystal morphology of magnesium carbonate trihydrate plays a crucial role; a uniform and stable crystal structure yields greater economic benefits.

[0005] This paper proposes a carbon dioxide absorption mineralization method that utilizes abundant magnesium resources in salt lake brine as mineralization raw materials and organic amines as absorbents to prepare a uniform and stable trihydrate magnesium carbonate product. This method can achieve carbon dioxide emission reduction while promoting the efficient utilization and transformation of salt lake resources.

[0006] Patent No. CN202410395597.8 provides a method and system for directly absorbing carbon dioxide using alkaline industrial solid waste. By selecting alkaline industrial solid waste as the raw material for DAC, specifically using carbide slag as the main component and other solid wastes as auxiliary components, and a small amount of additives, the mineralization and utilization of carbon dioxide is achieved.

[0007] Patent number CN202210838748.3 provides a method for the resource utilization of captured carbon dioxide, specifically involving the direct addition of a carbon dioxide absorbent to cement-based materials to achieve the utilization and mineralization of carbon dioxide. Patent No. CN202210108336.4 provides a method for absorbing and mineralizing carbon dioxide in waste gas. The method involves preparing a waste gas pretreatment liquid using wood ash and water; pretreating the waste gas using the pretreatment liquid; preparing an absorbent using an inorganic strong alkali, a weak acid, and water; removing carbon dioxide from the pretreated waste gas using the absorbent to obtain a carbon dioxide absorption product; and finally converting the carbon dioxide absorption product using waste gypsum and brine to achieve carbon dioxide mineralization and fixation. Summary of the Invention

[0009] A method for carbon dioxide absorption and mineralization, characterized by the following steps: Preparation steps: Prepare a simulated salt lake brine and an aqueous solution of ethanolamine of a certain concentration based on the Qinghai Qarhan Salt Lake; Mineralization reaction steps: Mix simulated salt lake brine and a certain amount of ethanolamine aqueous solution and add to a three-necked flask. Heat in a water bath and continuously introduce a mixture of carbon dioxide and nitrogen gas. Stir for a certain period of time to obtain the reaction solution. Exhaust gas treatment steps: After the gas participates in the mineralization reaction, the exhaust gas is passed through a condenser tube and then through concentrated sulfuric acid and degreased cotton for dehydration and drying. Finally, it enters a carbon dioxide infrared gas analyzer to determine the carbon dioxide content of the exhaust gas. Product processing steps: Stop the gas supply, vacuum filter the reaction solution, wash and dry it to obtain the mineralized product; Solution processing steps: Vacuum filtration was used to obtain the filtrate, which was then diluted to a fixed volume. The element content in the solution was determined by inductively coupled plasma atomic emission spectrometry.

[0010] According to the carbon dioxide absorption mineralization method described in claim 1, the simulated brine content of the salt lake is shown in the table below. element <![CDATA[Li + ]]> <![CDATA[Mg 2+ ]]> <![CDATA[K + ]]> <![CDATA[Na + ]]> <![CDATA[Cl - ]]> <![CDATA[B 2+ ]]> <![CDATA[SO4 2- ]]> g / L 1.98 37.61 4.30 3.75 121.6 2.22 2.52

[0011] The carbon dioxide absorption and mineralization method according to claim 1 is characterized in that a gas flow meter is used to control the gas flow rate in the reaction step.

[0012] According to the carbon dioxide absorption and mineralization method of claim 1, the retention time in the product processing step is 0-24h, the water bath temperature is 30℃-70℃, the reaction time is 60min, and the stirring speed is 200r / min.

[0013] According to the carbon dioxide absorption mineralization method of claim 1, the washing agent in the post-processing step is ultrapure water, and the product is placed in a drying oven at 50°C for 24 hours.

[0014] According to the carbon dioxide absorption and mineralization method of claim 1, the solution treatment step is characterized in that the filtrate obtained by filtration is diluted to a fixed volume, diluted 100 times, and the element content in the filtrate is determined. Attached Figure Description

[0015] Figure 1 The X-ray diffraction pattern of the mineralized product obtained in Example 1 of this invention. Figure 2 This is a scanning electron microscope image of the mineralized product obtained in Example 1 of the present invention. Figure 3 This is an X-ray diffraction pattern of magnesium carbonate trihydrate obtained in Example 2 of the present invention. Detailed Implementation Example

[0016] 50 ml of simulated salt lake brine solution and 50 ml of ethanolamine solution (1 mol / L) were prepared and placed in a three-necked flask. The flask was heated in a water bath, and a mixture of nitrogen and carbon dioxide was introduced at a flow rate of 40 mL / min and 50 mL / min, respectively. The water bath temperature was 50 °C, and the reaction was carried out for 60 min. After the reaction was complete, the mixture was vacuum filtered, washed with deionized water, and the resulting product was dried in a 50 °C oven for 24 h. The filtrate was diluted, and the magnesium and lithium concentrations were determined.

[0017] The product was tested and found to be magnesium carbonate trihydrate, with a magnesium mineralization rate of 61.35% and a lithium loss rate of 8%. The X-ray diffraction pattern of the product is shown below. Figure 1 Scanning electron microscope image (see) Figure 2 .

[0018] Example 2 50 ml of simulated salt lake brine solution and 50 ml of ethanolamine solution with a concentration of 1 mol / L were prepared and placed in a three-necked flask. The mixture was heated in a water bath, with nitrogen and carbon dioxide simulating flue gas at a flow rate of 40 mL / min and a nitrogen flow rate of 50 mL / min. The water bath temperature was 70 °C, and the reaction was carried out for 60 min. After the reaction was complete, the mixture was vacuum filtered, washed with deionized water, and the resulting product was dried in a 50 °C oven for 24 h. The filtrate was diluted, and the magnesium and lithium concentrations were determined.

[0019] The obtained product, upon testing, was found to be a mixture of magnesium carbonates, including basic magnesium carbonate, magnesium carbonate trihydrate, magnesium carbonate, and magnesium hydroxide. The magnesium mineralization rate was 71.78%, and the lithium loss rate was 12%. The X-ray diffraction pattern of the product is shown below. Figure 3 .

[0020] The above embodiments merely illustrate the implementation of the present invention, and their descriptions are relatively specific and detailed. However, they should not be construed as limiting the scope of the present invention. Any technical solutions obtained by adopting equivalent substitutions or equivalent transformations should fall within the protection scope of the present invention.

Claims

1. A method for carbon dioxide absorption and mineralization, characterized by the following steps: Preparation steps: Prepare a simulated salt lake brine and an aqueous solution of ethanolamine of a certain concentration based on the Qinghai Qarhan Salt Lake; Mineralization reaction steps: Mix simulated salt lake brine and a certain amount of ethanolamine aqueous solution and add to a three-necked flask. Heat in a water bath and continuously introduce a mixture of carbon dioxide and nitrogen gas. Stir for a certain period of time to obtain the reaction solution. Exhaust gas treatment steps: After the gas participates in the mineralization reaction, the exhaust gas is passed through a condenser tube and then through concentrated sulfuric acid and degreased cotton for dehydration and drying. Finally, it enters a carbon dioxide infrared gas analyzer to determine the carbon dioxide content of the exhaust gas. Product processing steps: Stop the gas supply, vacuum filter the reaction solution, wash and dry it to obtain the mineralized product; Solution processing steps: Vacuum filtration was used to obtain the filtrate, which was then diluted to a fixed volume. The elemental content in the solution was determined by inductively coupled plasma atomic emission spectrometry.

2. The carbon dioxide absorption mineralization method according to claim 1, the simulated salt lake brine content is shown in the table below.

3. The carbon dioxide absorption and mineralization method according to claim 1, characterized in that... The product processing steps include a retention time of 0–24 h, a water bath temperature of 30 °C–70 °C, a reaction time of 60 min, and a stirring speed of 200 r / min.

4. The carbon dioxide absorption and mineralization method according to claim 1, characterized in that... In the post-processing steps, ultrapure water was used as the detergent, and the product was placed in a drying oven at 50°C for 24 hours.

5. The carbon dioxide absorption and mineralization method according to claim 1, characterized in that... In the solution treatment step, the filtrate obtained by filtration is brought to a fixed volume, diluted 100 times, and the element content in the filtrate is determined.

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