Cesium carbonate modified layered double hydroxide/mesoporous alumina composite material as CO2Preparation method and application of adsorbent
阅读说明：本技术 碳酸铯改性层状双氢氧化物/介孔氧化铝复合材料作为co2吸附剂的制备方法和应用 (Cesium carbonate modified layered double hydroxide/mesoporous alumina composite material as CO2Preparation method and application of adsorbent ) 是由 叶青 吴凯 王兰洋 孟繁伟 于 2021-08-02 设计创作，主要内容包括：本发明提供了碳酸铯改性层状双氢氧化物/介孔氧化铝复合材料作为CO-(2)吸附剂的制备方法和应用。首先用原位法将层状双氢氧化物(LDH)沉积在介孔氧化铝(OMA)上组成的LDH-OMA复合材料,然后通过浸渍法将Cs-(2)CO-(3)负载于上述复合材料上,得到碳酸铯改性层状双氢氧化物/介孔氧化铝(Cs-(2)CO-(3)/LDH-OMA)复合材料作为低温CO-(2)吸附剂。本发明在宽的温度(25℃～200℃)范围内,对CO-(2)(浓度为5vol.％～25vol.％)和N-(2)(浓度为75vol.％～95vol.％)的混合气体具有较高的吸附能力,本发明吸附剂具有较高的比表面积和较好的热稳定性。(The invention provides a cesium carbonate modified layered double hydroxide/mesoporous alumina composite material as CO 2 A preparation method and application of the adsorbent. Firstly, depositing Layered Double Hydroxide (LDH) On Mesoporous Alumina (OMA) by in-situ method to form LDH-OMA composite material, and then soaking Cs by impregnation method 2 CO 3 Loading on the composite material to obtain cesium carbonate modified layered double hydroxide (DBM)Mesoporous alumina (Cs) 2 CO 3 /LDH-OMA) composite materials as low-temperature CO 2 An adsorbent. The invention can treat CO in a wide temperature range (25-200 ℃), and 2 (concentration of 5 vol.% to 25 vol.%) and N 2 The mixed gas (with the concentration of 75 vol.% to 95 vol.%) has high adsorption capacity, and the adsorbent has high specific surface area and good thermal stability.)
1. Cesium carbonate modified layered double hydroxide/mesoporous alumina composite material as CO2The preparation method of the adsorbent is characterized by comprising the following steps:
(1) preparation of LDH-OMA composite Carrier
Preparing a composite carrier by a coprecipitation method: dissolving 0.5-2 g of mesoporous alumina (OMA) in 100ml of deionized water, and stirring at room temperature for 0.5-3 h to obtain a uniformly dispersed OMA suspension; 0.036mol/L of Mg (NO)3)2·6H2O and 0.012mol/L Al (NO)3)3·9H2O preparing mixed liquid and keeping [ Mg2+]/[Al3+]2-3, adding the mixture into the suspension, and then adding a certain amount of 0.6-2 mol/L Na2CO3And 1.2-4 mol/L NaOH mixed solution, wherein [ Na2CO3]/[NaOH]Adjusting the pH value to be 10 +/-0.1, wherein the molar ratio is 2-10; mixing the aboveStirring the mixed solution in a water bath at 50-80 ℃ for 8-12 h, then carrying out suction filtration and washing until the pH value is 7, and drying in an oven at 80-100 ℃ to obtain LDH-OMA;
(2) impregnation method for preparing Cs2CO3/LDH-OMA composite adsorbent
By impregnating Cs2CO3Supported on LDH-OMA; firstly, (0.01-0.1 g) Cs2CO3Dissolving in 2-10 ml ethanol, and adding 1-5 g of the LDH-OMA [ LDH-OMA ]]:[Cs2CO3]Stirring the suspension for 2-10 h, and transferring the suspension to vacuum drying at 60 ℃; the sample obtained is designated xCs2CO3the/yLDH-OMA, x is Cs in the composite material2CO3And y is the mass percent of the loading of the LDH in the composite material.
2. The composite adsorbent prepared by the method of claim 1 for CO at low temperature2In the application of the adsorption, the method is characterized in that: placing the adsorbent in a thermogravimetric instrument, and introducing CO with the concentration of 5-25 vol%2And N at a concentration of 75 vol.% to 95 vol.%2The mixed gas of (2) is adsorbed, and the mass change of the adsorbent is used for detecting CO2The reaction temperature is 25-200 ℃.
Technical Field
The invention relates to Cs for adsorbing carbon dioxide2CO3Preparation method of modified layered double hydroxide/mesoporous alumina composite adsorbent and adsorption of CO under high-temperature condition2The use of (1).
Background
In recent years, environmental and energy issues have attracted worldwide attention. While many countries are developing and using more non-fossil fuel energy sources, the primary energy source is now derived from fossil fuel supplies. Therefore, in order to reduce the environmental impact of fossil fuels, people need to rationally plan and use fossil fuels. Carbon dioxide produced by the combustion of fossil fuels is one of the most important greenhouse gases and also one of the most important causes of global warming. Therefore, it is a task and an objective to control the emission of carbon dioxide, reduce the concentration of carbon dioxide in the atmosphere, and slow down global warming to build a green and environment-friendly home. Among the different sources of emissions, thermal power plants are one of the world's most prominent sources of carbon dioxide emissions, with power plants emitting approximately 20 million tons of carbon dioxide each year. In the past decades, the amount of carbon dioxide emitted worldwide has increased rapidly, and in particular, in developing countries represented by our country, the amount of carbon dioxide emitted in recent years has increased rapidly. According to the report of the inter-government committee on climate change (IPCC) of united nations, the amount of carbon dioxide in the atmosphere may reach 570ppm by 2100 years, which in turn may lead to an increase in the global average temperature of about 1.9 ℃ and an increase in the average sea level of 3.8 m. The adsorption method has wide application prospect due to low energy consumption and simple operation, and the key of the method is to select proper CO2Adsorbing the material. In recent years, with the research of novel solid adsorbents, the solid adsorption technology with low regeneration energy consumption, low environmental cost and no equipment corrosion problem shows good application prospect.
Ordered mesoporous materials MCM-41, SBA-15 and mesoporous alumina (OMA) have adjustable pore size and pore diameter due to their excellent high specific surface areaThe ordered pore structure is of interest. Hydrotalcite, also known as Layered Double Hydroxide (LDH). The general formula is as follows:LDHs have good adsorption properties and have good kinetics and regeneration properties. In the patent, a mesoporous material OMA with high specific surface area is used as a carrier, the mesoporous material OMA and a layered adsorption material LDH are combined to prepare a novel composite material LDH-OMA, and the OMA with high specific surface area is used as a carrier to deposit LDH with rich alkaline sites among and on the surfaces of pore channels; meanwhile, the Cs rich in more abundant alkaline sites2CO3Loading on LDH-OMA composite material by impregnation method. Cs finally obtained2CO3the/LDH-OMA composite adsorbent has higher specific surface area and abundant alkaline sites, and the composite material has very high CO at moderate regeneration temperature2Adsorption capacity. The implementation of this project resulted in: national science foundation project (number: 21277008; 20777005); beijing Natural science Foundation (number: 8082008); the subsidization of the national emphasis research and development program (No.2017YFC0209905) is also the research content of these projects.
Disclosure of Invention
The invention aims to provide a Cs2CO3Preparation of modified layered double hydroxide/OMA composite adsorbent and application of modified layered double hydroxide/OMA composite adsorbent in low-temperature CO2And (4) adsorbing. Layered Double Hydroxide (LDH) is deposited on OMA to form an LDH-OMA composite material by an in-situ method, and the OMA with high specific surface area is used as a carrier to deposit LDH with rich alkaline sites among and on the surfaces of pore channels; meanwhile, the Cs rich in more abundant alkaline sites2CO3Loading on LDH-OMA composite material by impregnation method. Cs finally obtained2CO3the/LDH-OMA composite adsorbent has higher specific surface area and abundant alkaline sites, and has excellent CO2Adsorption capacity and good regeneration performance. The composite material has high specific surface area: 300 to 425m2(ii) in terms of/g. The provided adsorbent can react with CO at a lower reaction temperature (25-200 ℃), and2has higher adsorption capacity. Among them, 5Cs2CO3The/30 LDH-OMA had the highest adsorption capacity (1.71mmol/g) 1.69 times that of unmodified SBA-15(1.01 mmol/g). The characterization result proves that the key factors for improving the adsorption performance of the composite material are the improvement of the specific surface area and the alkaline sites.
The invention provides a method for low-temperature CO2Adsorbed Cs2CO3The preparation method of the modified layered double hydroxide/OMA composite adsorbent comprises the following steps:
(1) a certain amount of OMA (0.5-2 g) is dissolved in 100ml of deionized water, and the mixture is stirred for 0.5-3 hours at room temperature to obtain an OMA suspension liquid with uniform dispersion. 0.036mol/L of Mg (NO)3)2·6H2O and 0.012mol/L Al (NO)3)3·9H2O is prepared into 50 to 200ml of mixed solution, added into the suspension, and then added with a certain amount of 0.6 to 2mol/L Na2CO3And 1.2-4 mol/L NaOH mixed solution, and adjusting the pH value to 10 +/-0.1. And stirring the mixed solution in a water bath at 50-80 ℃ for 8-12 h, then carrying out suction filtration and washing until the pH value is 7, and drying in an oven at 80-100 ℃ to obtain the LDH-OMA. Adding (0.01-0.1 g) Cs2CO3Dissolving the suspension in 2-10 ml ethanol, adding 1-5 g LDH-OMA, stirring the suspension for 2-10 h, and transferring the suspension to vacuum drying at 60 ℃. The sample obtained is designated xCs2CO3the/yLDH-OMA, x is Cs in the composite material2CO3And y is the mass percent of the loading of the LDH in the composite material.
(2) Placing the adsorbent in a thermogravimetric instrument, and introducing CO2(concentration of 5 vol.% to 25 vol.%) and N2(the concentration is 75 vol.% to 95 vol.%) of mixed gas, adsorbing the mixed gas, and detecting CO by mass change of the adsorbent2The reaction temperature is 25-200 ℃. Under the conditions, the adsorbent has high adsorption capacity (1.01-1.71 mmol/g).
Drawings
FIG. 1 shows OMA, 20LDH-OMA, 30LDH-OMA, 40LDH-OMA, 5Cs prepared according to the present invention2CO3XRD pattern of/30 LDH-OMA adsorbent.
FIG. 2 is a drawing of the present inventionPrepared LDH, OMA, 20LDH-OMA, 30LDH-OMA, 40LDH-OMA, 5Cs2CO3N of/30 LDH-OMA adsorbent2Adsorption/desorption scheme.
FIG. 3 shows OMA, 20LDH-OMA, 30LDH-OMA, 40LDH-OMA, 5Cs prepared according to the present invention2CO3The/30 LDH-OMA adsorbent adsorbs 15% CO at 50 deg.C2Adsorption pattern of the mixed gas for 2 hours.
FIG. 4 shows the preparation of 5Cs according to the present invention2CO3The/30 LDH-OMA adsorbent adsorbs 15% CO at 50 deg.C2The regeneration performance diagram of 10 times of adsorption and desorption of the mixed gas.
Detailed Description
The adsorbent is generally 5-30mg for experiment.
Example 1
(1) A certain amount of OMA (0.5g) is dissolved in 100ml of deionized water respectively, and the mixture is stirred for 0.5 to 3 hours at room temperature to obtain an OMA suspension liquid with uniform dispersion. 0.036mol/L of Mg (NO)3)2·6H2O and 0.012mol/L Al (NO)3)3·9H2O is prepared into 100ml of mixed solution, added into the suspension and then added with a certain amount of 0.6mol/L Na2CO3And 1.2mol/L NaOH mixed solution, and the pH is adjusted to 10 +/-0.1. The mixture was stirred in a water bath at 50 ℃ for 8h, then washed with suction until the pH became 7, and dried in an oven at 80 ℃ to obtain 20 LDH-OMA. Mixing (0.01g) Cs2CO3Dissolved in 2ml of ethanol, followed by addition of 1g of the above 20LDH-OMA, stirring the suspension for 3h and transferring it to vacuum drying at 60 ℃. The obtained sample was called 1Cs2CO3/20LDH-OMA。
(2) Placing the above certain amount of adsorbent (10mg) in a thermogravimetric instrument, introducing CO2(concentration 15 vol.%) and N2(85 vol.%) of the gas mixture, adsorbing it, and detecting CO by mass change of the adsorbent2The reaction temperature was 50 ℃.
Example 2
(1) A certain amount of OMA (1g) was dissolved in 100ml of deionized water and stirred at room temperature for 1h to give a well dispersed OMA suspension. 0.036mol/L of Mg (NO)3)2·6H2O and 0.012mol/L Al (NO)3)3·9H2O is prepared into 100ml of mixed solution, added into the suspension and then added with a certain amount of 1.2mol/L Na2CO3And 2mol/L NaOH mixed solution, and the pH is adjusted to 10 +/-0.1. The mixture was stirred in a water bath at 60 ℃ for 10 hours, then washed with suction until the pH became 7, and dried in an oven at 100 ℃ to obtain 30 LDH-OMA. Mixing (0.03g) Cs2CO3Dissolved in 4ml of ethanol, followed by addition of 1g of the above 30LDH-OMA, stirring the above suspension for 4h, transferring it to vacuum drying at 60 ℃. The obtained sample was named 3Cs2CO3/30LDH-OMA。
(2) Placing the above certain amount of adsorbent (10mg) in a thermogravimetric instrument, introducing CO2(concentration 15 vol.%) and N2(85 vol.%) of the gas mixture, adsorbing it, and detecting CO by mass change of the adsorbent2The reaction temperature was 50 ℃.
Example 3
(1) A certain amount of OMA (1.5g) was dissolved in 100ml of deionized water and stirred at room temperature for 2h to give a well dispersed OMA suspension. 0.036mol/L of Mg (NO)3)2·6H2O and 0.012mol/L Al (NO)3)3·9H2O is prepared into 100ml of mixed solution, added into the suspension and then added with a certain amount of 1.5mol/L Na2CO3And 3mol/L NaOH mixed solution, and the pH is adjusted to 10 +/-0.1. The mixture was stirred in a water bath at 70 ℃ for 12 hours, then washed with suction until the pH became 7, and dried in an oven at 100 ℃ to obtain 40 LDH-OMA. Mixing (0.05g) Cs2CO3Dissolved in 6ml of ethanol, followed by addition of 1g of the above LDH-OMA, stirring the suspension for 6h and transferring it to vacuum drying at 60 ℃. The obtained sample was named 5Cs2CO3/40LDH-OMA。
(2) Placing the above certain amount of adsorbent (10mg) in a thermogravimetric instrument, introducing CO2(concentration 15 vol.%) and N2(85 vol.%) of the gas mixture, adsorbing it, and detecting CO by mass change of the adsorbent2The reaction temperature was 50 ℃.
Example 4
(1) A certain amount of OMA (2g) was dissolved in 100ml of deionized water and stirred at room temperature for 3h to give a well dispersed OMA suspension. 0.036mol/L of Mg (NO)3)2·6H2O and 0.012mol/L Al (NO)3)3·9H2O is prepared into 200ml of mixed solution, added into the suspension and then added with a certain amount of 2mol/L Na2CO3And a 4mol/L NaOH mixed solution, and the pH is adjusted to 10 +/-0.1. The mixture was stirred in a water bath at 80 ℃ for 12 hours, then washed with suction until the pH became 7, and dried in an oven at 100 ℃ to obtain 50 LDH-OMA. Mixing (0.1g) Cs2CO3Dissolved in 10ml of ethanol, followed by addition of 1g of the above 50LDH-OMA, stirring the above suspension for 10 hours, and transferring it to vacuum drying at 60 ℃. The sample obtained is referred to as 10Cs2CO3/50LDH-OMA。
(2) Placing the above certain amount of adsorbent (10mg) in a thermogravimetric instrument, introducing CO2(concentration 15 vol.%) and N2(85 vol.%) of the gas mixture, adsorbing it, and detecting CO by mass change of the adsorbent2The reaction temperature was 50 ℃.