CO2 REVERSIBLE ADSORPTION MATERIAL, COMPOSITION AND REGENERATION METHOD THEREOF, AND CO2 CAPTURE METHOD

Abstract

Use of a zinc-aluminum spinel particle as a CO.sub.2 reversible adsorption material, a CO.sub.2 reversible adsorption material and a CO.sub.2 reversible adsorption composition, a CO.sub.2 capture method and a regeneration method of the CO.sub.2 reversible adsorption material or the CO.sub.2 reversible adsorption composition. The zinc-aluminum spinel particle having a specific microstructure has a micropore+mesopore porous structure and a relatively high specific surface area, thus having a function of adsorbing and capturing CO.sub.2 and being easy to regenerate, and is used as a CO.sub.2 adsorption and capture material with great application potential. The CO.sub.2 capture method can realize direct air capture of CO.sub.2, can be adapted to a variety of application scenarios, and has good universal applicability.

Claims

1. (canceled)

2. A CO.sub.2 reversible adsorption material, which is a zinc-aluminum spinel particle, wherein the zinc-aluminum spinel particle has a specific surface area of 190-380 m.sup.2/g, and comprising 5-13% of micropores and 87-95% of mesopores in percentage by volume.

3. A CO.sub.2 reversible adsorption composition, comprising, in percentage by weight, 10-90% of the CO.sub.2 reversible adsorption material according to claim 2 and a balance of water; and preferably, the CO.sub.2 reversible adsorption composition comprises, in percentage by weight, 40 to 60% of the CO.sub.2 reversible adsorption material according to claim 2 and the balance of water.

4. A CO.sub.2 capture method, wherein the capture method uses the CO.sub.2 reversible adsorption material according to claim 2 to capture CO.sub.2 in the air; preferably, a relative humidity of the air is 20-100%, preferably 30-90%, and more preferably 50-80%; and/or an ambient temperature during CO.sub.2 capture is 15-80 C., preferably 20-50 C.

5. A regeneration method of the CO.sub.2 reversible adsorption material according to claim 2, wherein the method comprises the step of heating the zinc-aluminum spinel particle after the capture of CO.sub.2 at a temperature of 70-400 C.; and preferably, the regeneration method comprises the step of heating the zinc-aluminum spinel particle after the capture of CO.sub.2 at a temperature of 10-300 C.

6. The adsorption material according to claim 2, wherein the zinc-aluminum spinel particle has the specific surface area of 230-350 m.sup.2/g; and/or the zinc-aluminum spinel particle comprises 5-13% of micropores, 75-85% of 2-10 nm mesopores and 7-12% of mesopores greater than or equal to 10 nm in percentage by volume.

7. The adsorption material according to claim 2, wherein the zinc-aluminum spinel particle has an average particle size of 2-10 nm, preferably 3-6 nm; and/or; the zinc-aluminum spinel particle has a pore volume of 0.3-1.2 cm.sup.3/g.

8. A method for preparing a zinc-aluminum spinel particle, comprising the following steps of: S1: respectively preparing a salt solution with a volume of V and containing Zn.sup.2+ and Al.sup.3+ and a precipitant solution; S2: adding an alkali liquor with a pH value of 9-10 into a reaction container, and then dripping the salt solution and the precipitant solution into the reaction container in parallel at a same speed for coprecipitation, wherein, in terms of volume, the pH value is controlled to be 7-9 when the first 20-50% of V is dripped, and the pH value is controlled to be reduced at a reduction range of 1-20% when a rest solution is dripped; and S3: aging after the coprecipitation is finished, and then drying and calcining an obtained solid at 300-400 C. to obtain the zinc-aluminum spinel particle; preferably, a molar ratio of Zn.sup.2+ to Al.sup.3+ in the salt solution containing Zn.sup.2+ and Al.sup.3+ is 0.5-1.5:2; and/or in the precipitant solution, the precipitant is one or more of sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, ammonium carbonate and ammonium bicarbonate, and a concentration of the precipitant is 0.1-0.5 g/mL.

9. The method according to claim 8, wherein the alkali liquor is an aqueous solution formed by one or more of sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, ammonium carbonate and ammonium bicarbonate, and a concentration of the alkali liquor is 0.05-2 mol/L; and/or an addition volume of the alkali liquor is 40-60% of V; and/or in the step S2, a temperature of the coprecipitation is 60-80 C.

10. The method according to claim 8, wherein in the step S3, the aging is carried out at a same temperature as the coprecipitation, and an aging time is 0.5-24 h; and/or the drying is carried out at 80-120 C. for 10-16 h; and/or the calcining is carried out at 300-350 C. for 3-6 h.

11. A CO.sub.2 capture method, wherein the capture method uses the CO.sub.2 reversible adsorption composition according to claim 3 to capture CO.sub.2 in the air; preferably, a relative humidity of the air is 20-100%, preferably 30-90%, and more preferably 50-80%; and/or an ambient temperature during CO.sub.2 capture is 15-80 C., preferably 20-50 C.

12. A regeneration method of the CO.sub.2 reversible adsorption composition according to claim 3, wherein the method comprises the step of heating the zinc-aluminum spinel particle after the capture of CO.sub.2 at a temperature of 70-400 C.; and preferably, the regeneration method comprises the step of heating the zinc-aluminum spinel particle after the capture of CO.sub.2 at a temperature of 10-300 C.

13. The adsorption composition according to claim 3, wherein the zinc-aluminum spinel particle has the specific surface area of 230-350 m.sup.2/g; and/or the zinc-aluminum spinel particle comprises 5-13% of micropores, 75-85% of 2-10 nm mesopores and 7-12% of mesopores greater than or equal to 10 nm in percentage by volume.

14. The capture method according to claim 4, wherein the zinc-aluminum spinel particle has the specific surface area of 230-350 m.sup.2/g; and/or the zinc-aluminum spinel particle comprises 5-13% of micropores, 75-85% of 2-10 nm mesopores and 7-12% of mesopores greater than or equal to 10 nm in percentage by volume.

15. The capture method according to claim 11, wherein the zinc-aluminum spinel particle has the specific surface area of 230-350 m.sup.2/g; and/or the zinc-aluminum spinel particle comprises 5-13% of micropores, 75-85% of 2-10 nm mesopores and 7-12% of mesopores greater than or equal to 10 nm in percentage by volume.

16. The regeneration method according to claim 5, wherein the zinc-aluminum spinel particle has the specific surface area of 230-350 m.sup.2/g; and/or the zinc-aluminum spinel particle comprises 5-13% of micropores, 75-85% of 2-10 nm mesopores and 7-12% of mesopores greater than or equal to 10 nm in percentage by volume.

17. The regeneration method according to claim 12, wherein the zinc-aluminum spinel particle has the specific surface area of 230-350 m.sup.2/g; and/or the zinc-aluminum spinel particle comprises 5-13% of micropores, 75-85% of 2-10 nm mesopores and 7-12% of mesopores greater than or equal to 10 nm in percentage by volume.

18. The adsorption composition according to claim 3, wherein the zinc-aluminum spinel particle has an average particle size of 2-10 nm, preferably 3-6 nm; and/or; the zinc-aluminum spinel particle has a pore volume of 0.3-1.2 cm.sup.3/g.

19. The capture method according to claim 4, wherein the zinc-aluminum spinel particle has an average particle size of 2-10 nm, preferably 3-6 nm; and/or; the zinc-aluminum spinel particle has a pore volume of 0.3-1.2 cm.sup.3/g.

20. The regeneration method according to claim 5, wherein the zinc-aluminum spinel particle has an average particle size of 2-10 nm, preferably 3-6 nm; and/or; the zinc-aluminum spinel particle has a pore volume of 0.3-1.2 cm.sup.3/g.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0056] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings required in the examples will be briefly described below. It should be understood that the following drawings illustrate only certain examples of the present disclosure, and therefore should not be regarded as limiting the scope of the present disclosure.

[0057] FIG. 1 is a TEM image of a zinc-aluminum spinel particle prepared in Example 1, wherein FIG. 1A is a TEM image of the zinc-aluminum spinel particle (scale: 5 nm), FIG. 1B is a partially enlarged image of FIG. 1A, and FIG. 1C is a standard schematic structural diagram of the zinc-aluminum spinel particle.

[0058] FIG. 2 is a TEM image (scale: 20 nm) of the zinc-aluminum spinel particle prepared in Example 1.

[0059] FIG. 3 is a graph of nitrogen physical adsorption and desorption of zinc-aluminum spinel particles prepared in Examples 1-4.

[0060] FIG. 4 is a TEM image of a zinc-aluminum spinel particle prepared in Comparative Example 1.

[0061] FIG. 5 is an XRD pattern of the zinc-aluminum spinel particle prepared in Example 1 at different adsorption times.

[0062] FIG. 6 is an XRD pattern of the zinc-aluminum spinel particle prepared in Example 1 at different degrees of crystallinity.

DETAILED DESCRIPTION

[0063] The embodiments of the present disclosure will be described in detail below with reference to specific embodiments, but those skilled in the art will understand that the following embodiments are only used to illustrate the present disclosure, and should not be regarded as limiting the scope of the present disclosure. Those embodiments without indicating specific conditions are carried out according to conventional conditions or conditions suggested by the manufacturers. Those reagents or instruments without indicating manufacturers are all conventional products that can be obtained through commercially available purchases.

[0064] Raw materials or reagents used in the embodiments and comparative examples of the present disclosure are all commercially available.

[0065] Percentages used in the embodiments and comparative examples of the present disclosure are all mass percentages unless otherwise specified.

[0066] In the embodiments and comparative examples of the present disclosure, a specific surface area and a pore structure of an obtained product can be obtained through a test result of a nitrogen physical adsorption instrument, a pore volume of the product is calculated, and the test result is shown in FIG. 3 (the higher a closed-loop area formed by a desorption curve, the larger the specific surface of the product, and a hysteresis loop appearing between relative pressures of 0.6-1 indicates that the obtained product structure has a mesopore of 2-50 nm).

[0067] A method for calculating a degree of crystallinity used in the test example of the present disclosure is as follows:

[0068] Diffraction peak areas of basic carbonate (characteristic diffraction peak at 10, 24, 35, 38 and 47) and zinc-aluminum spinel (characteristic diffraction peak is the wide peak between 30 and 40) were calculated using XRD data processing software EVA of Bruker Corporation, denoted as S.sub.c and S.sub.me respectively, and a peak area of an amorphous portion in a zinc-aluminum spinel phase was described as S.sub.mm using background function in EVA, a ratio of (S.sub.c+S.sub.mc)/(S.sub.c+S.sub.mc+S.sub.mm) represents a relative content of the crystalline phase in the sample to evaluate a degree of crystallinity of the crystalline phase after the zinc-aluminum spinel absorbs CO.sub.2. That is, the degree of crystallinity %=(S.sub.c+S.sub.mc)/(S.sub.c+S.sub.mc+S.sub.mm)100%.

[0069] The air at room temperature in the test example of the present disclosure refers to an air temperature of 21-25 C. and a relative humidity of 50-70%.

Example 1

[0070] 828 g of zinc nitrate hexahydrate and 2,087 g of aluminum nitrate nonahydrate were weighed and added with water to prepare a 4 L aqueous solution for use, and recorded as a precipitant A. 1,200 g of sodium carbonate was weighed and added with water to prepare a 4 L aqueous solution for later use, and recorded as a precipitant B. In a 10 L reaction kettle, firstly, 2 L of potassium bicarbonate with a concentration of 0.1 mol/L was added to a bottom of the kettle, and then the precipitant A and the precipitant B began to be dripped in parallel, keeping the precipitant A and the precipitant B to be precipitated at a constant speed of 40 mL/min and controlling a temperature of the reaction kettle to be 70 C., controlling the pH value to 8 when the first 30% (volume ratio) of solution (i.e., the first 30% of the respective volumes of the precipitant A and the precipitant B were dripped in parallel) was dripped and controlling a pH value to 7 when the later 70% (volume ratio) of solution (i.e., the later 70% of the respective volumes of the precipitant A and the precipitant B were dripped in parallel) was dripped. After the precipitation, the reaction solution was continuously stirred for 0.5 h at the same temperature and then cooled down. The mixture was filtered. A filter cake was washed repeatedly until a conductivity of an eluate was less than 50 S/cm, and dried at 110 C. for 15 h to remove free water in the filter cake to form a precursor with a moisture content less than 1%. The precursor was transferred to a muffle furnace for calcination, and a calcination temperature was controlled at 350 C. After calcining for 5 h, the zinc-aluminum spinel particles were obtained, and TEM images thereof were shown in FIG. 1A and FIG. 2.

[0071] As shown in FIG. 1, it can be seen from FIG. 1B and FIG. 1C that the obtained particles are of a zinc-aluminum spinel structure, and does not contain dispersed ZnO particles.

[0072] The zinc-aluminum spinel particles have an average size of 3.8 nm. In the spinel particles, a ratio of micropores less than 2 nm accounts for 9%, a ratio of pores of 2-10 nm accounts for 84%, and a ratio of pores of 10-50 nm accounts for 7%, a specific surface area is 258.7 m.sup.2/g, and a pore volume is 0.38 cm.sup.3/g.

Example 2

[0073] 828 g of zinc nitrate hexahydrate and 2,087 g of aluminum nitrate nonahydrate were weighed and added with water to prepare a 4 L aqueous solution for use, and recorded as a precipitant A. 1,000 g of sodium carbonate was weighed and added with water to prepare a 4 L aqueous solution for later use, and recorded as a precipitant B. In a 10 L reaction kettle, firstly, 2 L of sodium bicarbonate with a concentration of 0.05 mol/L was added to a bottom of the kettle, and then the precipitant A and the precipitant B began to be dripped in parallel, keeping the precipitant A and the precipitant B to be precipitated at a constant speed of 50 mL/min and controlling a temperature of the reaction kettle to be 80 C., controlling a pH value to 8 when the first 20% (volume ratio) of solution (i.e., the first 20% of the respective volumes of the precipitant A and the precipitant B were dripped in parallel) was dripped and controlling the pH value to 6.5 when the later 80% (volume ratio) of solution (i.e., the later 80% of the respective volumes of the precipitant A and the precipitant B were dripped in parallel) was dripped. After the precipitation, the reaction solution was continuously stirred for 1 h at the same temperature and then cooled down. The mixture was filtered. A filter cake was washed repeatedly until a conductivity of an eluate was less than 50 S/cm, and dried at 110 C. for 10 h to remove free water in the filter cake to form a precursor with a moisture content less than 1%. The precursor was transferred to a muffle furnace for calcination, and a calcination temperature was controlled at 300 C. After calcining for 3 h, the zinc-aluminum spinel particles were obtained.

[0074] The zinc-aluminum spinel particles have an average size of 4.8 nm. In the spinel particles, a ratio of micropores less than 2 nm accounts for 9%, a ratio of pores of 2-10 nm accounts for 82%, and a ratio of pores of 10-50 nm accounts for 9%, a specific surface area is 264.1 m.sup.2/g, and a pore volume is 0.48 cm.sup.3/g

Example 3

[0075] 828 g of zinc nitrate hexahydrate and 2,087 g of aluminum nitrate nonahydrate were weighed and added with water to prepare a 4 L aqueous solution for use, and recorded as a precipitant A. 1,300 g of sodium carbonate was weighed and added with water to prepare a 4 L aqueous solution for later use, and recorded as a precipitant B. In a 10 L reaction kettle, firstly, 2 L of ammonium bicarbonate with a concentration of 1.5 mol/L was added to a bottom of the kettle, and then the precipitant A and the precipitant B began to be dripped in parallel, keeping the precipitant A and the precipitant B to be precipitated at a constant speed of 60 mL/min and controlling keeping a temperature of the reaction kettle to be 75 C., controlling a pH value to 9 when the first 50% (volume ratio) of solution (i.e., the first 50% of the respective volumes of the precipitant A and the precipitant B were dripped in parallel) was dripped and controlling the pH value to 8 when the later 50% (volume ratio) of solution (i.e., the later 50% of the respective volumes of the precipitant A and the precipitant B were dripped in parallel) was dripped. After the precipitation, the reaction solution was continuously stirred for 1 h at the same temperature and then cooled down. The mixture was filtered. A filter cake was washed repeatedly until a conductivity of an eluate was less than 50 S/cm, and dried at 110 C. for 16 h to remove free water in the filter cake to form a precursor with a moisture content less than 1%. The precursor was transferred to a muffle furnace for calcination, and a calcination temperature was controlled at 320 C. After calcining for 5 h, the zinc-aluminum spinel particles were obtained.

[0076] The zinc-aluminum spinel particles have an average size of 5.1 nm. In the spinel particles, a ratio of micropores less than 2 nm accounts for 6%, a ratio of pores of 2-10 nm accounts for 82%, and a ratio of pores of 10-50 nm accounts for 12%, a specific surface area is 233.5 m.sup.2/g, and a pore volume is 0.35 cm.sup.3/g.

Example 4

[0077] 828 g of zinc nitrate hexahydrate and 2,087 g of aluminum nitrate nonahydrate were weighed and added with water to prepare a 4 L aqueous solution for use, and recorded as a precipitant A. 1,200 g of sodium carbonate was weighed and added with water to prepare a 4 L aqueous solution for later use, and recorded as a precipitant B. In a 10 L reaction kettle, firstly, 2 L of alkali liquor (mixture of sodium bicarbonate to potassium bicarbonate in a mass ratio of 1:1) with a concentration of 0.01 mol/L was added to a bottom of the kettle, and then the precipitant A and the precipitant B began to be dripped in parallel, keeping the precipitant A and the precipitant B to be precipitated at a constant speed of 30 mL/min and controlling a temperature of the reaction kettle to be 60 C., controlling a pH value to 7 when the first 30% (volume ratio) of solution (i.e., the first 30% of the respective volumes of the precipitant A and the precipitant B were dripped in parallel) was ripped and controlling the pH value to 6.8 when the later 70% (volume ratio) of solution (i.e., the later 70% of the respective volumes of the precipitant A and the precipitant B were dripped in parallel) was dripped. After the precipitation, the reaction solution was continuously stirred for 1 h at the same temperature and then cooled down. The mixture was filtered. A filter cake was washed repeatedly until a conductivity of an eluate was less than 50 S/cm, and dried at 110 C. for 14 h to remove free water in the filter cake to form a precursor with a moisture content less than 3%. The precursor was transferred to a muffle furnace for calcination, and a calcination temperature was controlled at 320 C. After calcining for 5 h, the zinc-aluminum spinel particles were obtained.

[0078] The zinc-aluminum spinel particles have an average size of 3.4 nm. In the spinel particles, a ratio of micropores less than 2 nm accounts for 12%, a ratio of pores of 2-10 nm accounts for 82%, and a ratio of pores of 10-50 nm accounts for 12%, a specific surface area is 348.2 m.sup.2/g, and a pore volume is 1.01 cm.sup.3/g.

Comparative Example 1

[0079] 828 g of zinc nitrate hexahydrate and 2,087 g of aluminum nitrate nonahydrate were weighed and added with water to prepare a 4 L aqueous solution for use, and recorded as a precipitant A. 1,200 g of sodium carbonate was weighed and added with water to prepare a 4 L aqueous solution for later use, and recorded as a precipitant B. In a 10 L reaction kettle, the precipitant A and the precipitant B were dripped in parallel, keeping the precipitant A and the precipitant B to be precipitated at a constant speed and controlling a temperature of the reaction kettle to be 80 C., controlling a pH value in the reaction kettle to be 8. A flow rate of the precipitant A and the precipitant B was 100 mL/min. After the precipitation, the reaction solution was continuously stirred for 2-3 h at the same temperature and then cooled down. The mixture was filtered. A filter cake was dried until a moisture content thereof was less than 1%, and then transferred to a muffle furnace for calcination at a calcination temperature of 700 C., calcining for 5 h, and then taking out to obtain the zinc-aluminum spinel particles, a TEM image of which was shown in FIG. 4.

[0080] The zinc-aluminum spinel particles have an average size of 36 nm, are single pore domain materials of 50 nm or more, have a specific surface area of 60 m.sup.2/g, and a pore volume of 0.14 cm.sup.3/g.

Comparative Example 2

[0081] ZnO and Al.sub.2O.sub.3 were physically mixed according to an atomic molar ratio of ZnAl.sub.2O.sub.4 (i.e. a molar ratio of ZnO to Al.sub.2O.sub.3 being 1:1) to obtain a mixture.

Comparative Example 3

[0082] Basic zinc carbonate and Al.sub.2O.sub.3 were physically mixed according to an atomic molar ratio of ZnAl.sub.2O.sub.4 (i.e. a molar ratio of Zn.sub.2(OH).sub.2CO.sub.3 to Al.sub.2O.sub.3 being 1:2) to obtain a mixture.

Test Example 1

[0083] The product samples prepared in Examples 1-4 and Comparative Examples 1-3 were placed directly into air at room temperature for two weeks, subjected to XRD test once, continuously placed for four weeks, then subjected to XRD test once, and the results were shown in Table 1.

TABLE-US-00001 TABLE 1 Test result after Test result after two weeks four weeks Serial (Degree of (Degree of No. Source of test sample crystallinity) crystallinity) 1 Example 1 13% 27% 2 Example 2 18% 32% 3 Example 3 10% 25% 4 Example 4 15% 30% 5 Comparative Example 1 6 Comparative Example 2 7 Comparative Example 3

[0084] The test results in Table 1 show that the zinc-aluminum spinel particle products prepared in Examples 1-4 could directly react with the moisture and the CO.sub.2 in the air. After two weeks, the XRD test results show that new diffraction peaks appeared near 10, 24, 35, 38 and 47. According to the comparison with a standard spectrum (PDF48-1023), a basic carbonate structure containing zinc-aluminum (expressed as (Al.sub.0.31Zn.sub.0.7)(OH).sub.2(CO.sub.3).sub.0.167.Math.H.sub.2O) appeared in the material. Continuing to place the products in the air for reaction with the moisture and the CO.sub.2, as the basic carbonate structure increased, the crystallinity was further increased. After four weeks, the crystallinity reached a range of 25-32%.

[0085] The product of Example 1 was continuously placed for eight weeks, and the original product and the products after each week were tested by XRD, as shown in FIG. 5 (mainly showing the characteristic diffraction peaks greater than or equal to 15). It could be seen that there were no characteristic diffraction peaks near 10, 24, 35, 38 and 47 in the spectrogram of the original product. After being placed in the air, the characteristic diffraction peak of the basic carbonate began to appear, and the crystallinity was gradually increased with the extension of the placing time.

[0086] The degree of crystallinity of the product of Example 1 after placing for eight weeks reached 27.7%. The product was dried in an oven at 125 C. for 10 h until the characteristic diffraction peak in the XRD pattern disappeared; and then 1.2 times of water in terms of weight was added to the regenerated spinel product obtained, stirred uniformly and continuously placed in the air at room temperature for a period of time. The XRD pattern showed that the characteristic diffraction peak of the basic carbonate appeared again, and in this case, the crystallinity reached 53.1%, as shown in FIG. 6.

[0087] In contrast, after the products prepared in Comparative Examples 1-3 were placed for two weeks, the XRD results showed that the characteristic diffraction peak of the basic carbonate was not found, indicating that the corresponding basic carbonate structure containing zinc-aluminum was not formed. The formation of the basic carbonate structure was not found after four weeks.

[0088] The test results of Comparative Example 1 showed that even if the same zinc-aluminum spinel materials were used, the material of Comparative Example 1 cannot achieve the function of adsorbing the CO.sub.2 in the air due to the difference of the microstructure, especially the difference between the pore structure and the specific surface area.

[0089] The test results of Comparative Example 2 showed that although the resulting mixture had the same element composition as the spinel products of the examples, the resulting mixture included two different phases, which were different from the spinel phase structure, and thus cannot achieve the function of adsorbing the CO.sub.2 in the air.

[0090] The mixture product prepared in Comparative Example 3 was heated at 125 C. to convert the basic zinc carbonate therein to ZnO, placed in the air at room temperature for two weeks, and then subjected to XRD test. The results showed that the formation of the basic carbonate structure was still not found, which also sidewise illustrated the basic carbonate formed by the zinc-aluminum spinel particles products of the examples after adsorption of the CO.sub.2 (i.e. a specific basic carbonate structure with a certain crystallinity) was not a conventional basic zinc carbonate.

Test Example 2

[0091] 10 g of the product samples prepared in Examples 1-4 and Comparative Examples 1-3 were weighed; and then 1.2 times of water in terms of weight was added, stirred uniformly and placed in the air at room temperature, the samples were reacted with the CO.sub.2 in the air for 15 h and then subjected to XRD test and the crystallinity was calculated.

[0092] The test results showed that the samples in Examples 1-4 all formed a basic carbonate structure containing zinc-aluminum (the degrees of crystallinity were about 52%, 57%, 48% and 41% respectively, and the adsorption capacity of CO.sub.2 was about 3.2-3.7% in terms of weight, which could be obtained by conversion). Thus, the zinc-aluminum spinel products in the examples compounded with water accelerated the CO.sub.2 adsorption rate.

[0093] The test results showed that no corresponding basic carbonate structure was found in the products prepared in Comparative Examples 1-3, and the function of adsorbing the CO.sub.2 in the air cannot be achieved after compounding with water.

Test Example 3

[0094] The product obtained in Example 2 after CO.sub.2 adsorption in Test Example 2 was placed in an oven at 110 C. for drying for 4 h, the obtained sample was increased by 8.3% relative to an original weight (in this case, the degree of crystallinity was about 57%), the sample was continuously placed in an oven at 150 C. and dried for 10 h, and the weight of the sample was further lost until the original spinel weight was recovered, thereby achieving regeneration of the zinc-aluminum spinel product.

[0095] The operation of Test Example 2 was repeated, and then water was added to the regenerated spinel product again according to a weight ratio of 1:1.2, stirred uniformly and then placed in the air at room temperature. After the sample was reacted with the CO.sub.2 in the air for 10 h, XRD test was performed, and the results showed that the basic carbonate structure was found, and crystallinity was about 48%. The sample was placed in an oven at 110 C. and dried for 4 h to remove free water in the sample, and the sample was increased by 8.2% relative to the original weight, the sample was continuously placed in an oven at 150 C. for 10 h, and the original spinel weight was recovered. XRD test showed that the original spinel structure was recovered again.

[0096] The above cycle of adsorbing CO.sub.2 by adding waterand releasing CO.sub.2 by heating was repeated until the spinel structure in the tenth cycle was substantially unchanged. After the tenth cycle, the structure begun to have very little loss which was no more than 1%. Thus, it could be inferred that the zinc-aluminum spinel of the present disclosure could at least last for 100 cycles of adsorbing CO.sub.2 by adding waterand releasing CO.sub.2 by heating.

[0097] Unless specifically limited, the terms used in the present disclosure are all meanings commonly understood by those skilled in the art.

[0098] The embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the present disclosure, and those skilled in the art can make various other substitutions, changes and improvements within the scope of the present disclosure, and therefore, the present disclosure is not limited to the above embodiments, but only limited by the claims.