CN105664841A - Hydration-calcination modification method of high temperature CO2 adsorption material Li4SiO4 - Google Patents

Abstract

The invention relates to a hydration-calcination modification method of a high-temperature CO2 adsorption material Li4SiO4. Lithium silicate powder synthesized by a solid phase method is modified by a hydration-calcination method. Hydration temperature is 80-100 DEG C, calcination temperature is 700-900 DEG C, and calcination time is 2-6 h. Average particle size of an adsorbent is less than 50 micrometers, absorption capacity is greater than 25%, and absorptive capacity is not obviously attenuated after 15 times of circulations. Pore structure of the lithium silicate material prepared after modification is more abundant, and the material has high carbon dioxide adsorption rate and absorptive capacity and has good cyclic adsorption performance.

Description

Hydration-calcination modification method of high temperature CO2 adsorption material Li4SiO4

technical field

The invention belongs to the technical field of materials, and in particular relates to a modified preparation method of a lithium silicate material used for absorbing high-temperature carbon dioxide. The material can be used for absorbing carbon dioxide discharged from flues of fossil fuel power plants and cement pits.

Background technique

With the rapid development of modern industry, the consumption of fossil energy is increasing year by year, and a large amount of CO ₂ emitted during its utilization has caused a serious greenhouse effect. Fossil fuel power plants are the main source of CO ₂ emissions, and the CO ₂ emitted from the high-temperature furnace has a high temperature. The high-temperature flue gas circulation removal method can avoid the cooling treatment before CO ₂ separation and reduce the CO ₂ capture and separation process. Energy loss, the need to achieve energy saving and emission reduction. Therefore, the synthesis of excellent materials capable of reversibly absorbing CO ₂ at high temperatures has important theoretical significance and practical application value for reducing CO ₂ gas emissions in the combustion process of fossil fuel power plants. Lithium silicate material is considered to be one of the best materials for _CO2 adsorption at high temperature, it has high absorption capacity, good recyclability at high temperature, and provides great potential for reducing _CO2 emissions from high temperature furnaces new way.

The preparation methods of Li ₄ SiO ₄ adsorbent mainly include high temperature solid synthesis method, sol-gel method and precipitation method. In recent years, researchers from various countries have shown that reducing particle size, increasing particle specific surface area, and improving material activity can effectively improve the adsorption performance of Li ₄ SiO ₄ materials. Although the sample particles synthesized by the sol-gel method are finer, compared with the solid-phase method, its preparation cost is high and the synthesis time is long.

Contents of the invention

The object of the present invention is to provide a hydration-calcination modification method of Li ₄ SiO ₄ , a high-temperature CO ₂ adsorption material, which has low modification cost and good CO ₂ adsorption effect after modification.

The technical solution of the present invention is: a hydration-calcination method modification method for high _- temperature _CO2 adsorption material _Li4SiO4 , the lithium silicate powder synthesized by solid-phase method is modified by hydration-calcination method, and the hydration temperature is 80~ 100°C, the calcination temperature is 700°C-900°C, the calcination time is 2h-6h, the average particle size of the adsorption material is less than 50 microns, the absorption capacity is greater than 25%, and the absorption capacity has no obvious attenuation after 15 cycles.

The specific method for synthesizing lithium silicate powder by the solid-phase method is as follows: lithium carbonate and silicon dioxide are uniformly mixed, ground and dried with alcohol, and then calcined at high temperature to obtain lithium silicate powder.

The hydration-calcination method specifically includes: adding lithium silicate powder synthesized by solid-phase method into water, fully reacting under constant stirring in a water bath, drying, and then calcining.

During hydration, keep the water volume constant.

The Li ₄ SiO ₄ high-temperature CO ₂ adsorbent obtained by the hydration-calcination method modification method of the Li ₄ SiO ₄ high-temperature CO ₂ adsorbent is modified by the hydration-calcination method for the solid-phase synthesis of lithium silicate, and the hydration The temperature is 80-100°C, the calcination temperature is 700-900°C, and the calcination time is 2h-6h. The average particle size of the adsorbent is less than 50 microns, and the absorption capacity is greater than 25%. After 15 cycles of adsorption and desorption cycles, the absorption capacity No significant attenuation.

Beneficial effect:

(1) The adsorbent is modified by hydration, the method is simple and the price is low. Constant stirring is required during the hydration process, and water evaporation should be avoided.

(2) The modified adsorbent has richer pore structure, higher carbon dioxide adsorption rate and larger adsorption capacity. It can directly absorb a large amount of high-temperature carbon dioxide emitted from the exhaust flue of cement kilns and glass factories.

(3) The recycling performance is good, and it still has good adsorption performance after 15 cycles of adsorption/desorption cycles.

Description of drawings

Fig. 1. In embodiment 1, lithium silicate sample adsorption CO ₂ thermogravimetric curves before and after modification.

Figure 2. In Example 1, the absorption/desorption cycle performance of lithium silicate samples before and after modification.

Fig. 3. In embodiment 1, the electron micrograph of lithium silicate sample before and after modification.

detailed description

Example 1

Mix lithium carbonate and silicon dioxide with a molar ratio of 2:1 evenly, add an appropriate amount of alcohol to grind and mix, and then dry. The mixed powder was put into a muffle furnace for calcination at 800° C. for 4 hours to obtain lithium silicate powder. Put the prepared lithium silicate powder (1-2g) into a 500ml beaker filled with water, then place the beaker in a water bath at 80°C and stir continuously, take it out after 8 hours, and dry it at 105°C. The dried powder was put into the muffle furnace again, and calcined at 800° C. for 4 hours to obtain lithium silicate powder.

Put the lithium silicate powder before and after modification into the thermogravimetric analyzer, in the 99.999% _N2 atmosphere, raise the temperature to 680°C at a rate of 10K/min, and then switch to the 99.999% _CO2 atmosphere, at 680°C The _CO2 absorption reaction was carried out at a constant temperature for 2 hours, and the obtained thermogravimetric curve is shown in Figure 1. The maximum adsorption capacity of the lithium silicate samples before and after modification was 23.8% and 30.3%, respectively.

The lithium silicate powder before and after modification was tested in a dual-temperature zone tube furnace for multiple cycle adsorption tests. The test method was as follows: during the cycle test of absorption and desorption, CO ₂ and N ₂ were introduced respectively, and the flow rate was 1.0 L/min, the corresponding furnace temperature is divided into 680°C and 800°C. During the test, the samples were weighed and evenly spread in the corundum ark to form a thin layer. After reacting in the carbonation furnace at 680°C for 30 minutes, weighed, and then entered the calciner for 10 minutes of calcination, and the test was repeated in this way. After 15 cycles, the _CO2 uptake is shown in Fig. 2. The absorption rates of W-Li ₄ SiO ₄ after modification and S-Li ₄ SiO ₄ before modification were maintained at about 27% and 11%, respectively, and the absorption capacity of the samples did not decay significantly.

Using a scanning electron microscope, the lithium silicate powder before and after modification is observed, as shown in Figure 3, wherein (a) is before modification and (b) is the SEM image after modification. It can be seen from the figure that hydration-calcination modification After curing, the average particle size of the particles is reduced from 200 μm to 50 μm.

Example 2

Reference Example 1 was hydrated and calcined to prepare a lithium silicate adsorbent, and the _CO2 adsorption test was carried out under the same conditions, except that the hydration temperature was 100°C and the hydration time was 4h, and the _CO2 absorption capacity was 29.7%.

Example 3

Reference Example 1 was hydrated-calcined to prepare a lithium silicate adsorbent, and the _CO2 adsorption test was carried out under the same conditions. The difference was that the calcination time was 2h and 6h, and the _CO2 absorption capacity was 32.3% and 25.5%.

Claims (5)

1. a high temperature CO₂Adsorbing material Li₄SiO₄Hydration-calcining method of modifying, it is characterised in that: to Solid phase synthesis lithium silicate powder adopt hydration-method for calcinating be modified, hydration temperature is 80 ~ 100 DEG C, and calcining heat is 700 DEG C ~ 900 DEG C, and calcination time is 2h~6h, described adsorbing material mean diameter is less than 50 microns, and absorptive capacity is more than 25%, and after 15 circulation absorption desorption cycle, absorptive capacity is without obvious decay.

2. high temperature CO according to claim 1₂Adsorbing material Li₄SiO₄Hydration-calcining method of modifying, it is characterised in that: described Solid phase synthesis lithium silicate powder method particularly includes: lithium carbonate and after silicon dioxide mix homogeneously ethanol mill-drying, high-temperature calcination obtains lithium silicate powder again.

3. high temperature CO according to claim 1₂Adsorbing material Li₄SiO₄Hydration-calcining method of modifying, it is characterised in that: described hydration-method for calcinating is particularly as follows: be added to the water Solid phase synthesis lithium silicate powder, after water-bath is stirred continuously lower reaction fully, dries, then calcines.

4. high temperature CO according to claim 1₂Adsorbing material Li₄SiO₄Hydration-calcining method of modifying, it is characterised in that: in hydro-combination process, keep the water yield constant.

5. according to the arbitrary described high temperature CO of claim 1 ~ 4₂Adsorbing material Li₄SiO₄The Li that obtains of hydration-calcining method of modifying₄SiO₄, it is characterised in that: adopting hydration-method for calcinating to be modified Solid phase synthesis Lithium metasilicate, hydration temperature is 80 ~ 100 DEG C, and calcining heat is 700 DEG C ~ 900 DEG C, and calcination time is 2h~6h, Li₄SiO₄Mean diameter is less than 50 microns, and absorptive capacity is more than 25%, and after 15 times circulate, absorptive capacity is without obvious decay.