Coated nanocluster and method for producing same

Abstract

A coated nanocluster (10) comprises: a core (20) including an aggregate of magnesium oxide particles; and a shell (30) covering the core (20). The shell (30) has a coating layer (31) containing at least one of a nitrate and a nitrite, and carbonate particles (32) dispersed in the coating layer (31). At least one of the nitrate and the nitrite contains an alkali metal ion. The carbonate particles (32) contain at least one selected from a calcium ion, a strontium ion, and a barium ion. The molar ratio of the carbonate particles (32) constituting the shell (30) to the magnesium oxide particles constituting the core (20) is more than 0.005 and 0.015 or less.

Description

Coated nanoclusters and methods for producing same

[0001] This disclosure relates to coated nanoclusters and methods for producing the same. This application claims priority to Japanese Patent Application No. 2024-138932, filed on August 20, 2024, the contents of which are incorporated herein by reference.

[0002] In Patent Document 1, CO ２ Disclosed is a coated nanocluster for gas adsorption, comprising a core including a collection of magnesium oxide particles and a shell surrounding the core, the shell including at least one of a nitrate and a nitrite, the at least one of the nitrate and the nitrite including an alkali metal ion.

[0003] Non-Patent Document 1 describes calcium carbonate (CaCO ３ ), strontium carbonate (SrCO ３ ) or barium carbonate (BaCO ３ ) to the core, the CO ２ It is said that the gas adsorption rate is improved.

[0004] US Patent No. 10,322,399 (B)

[0005] "Unravelling the role of alkaline earth metal carbonates in intermediate temperature CO2 capture using alkali metal salt-promoted MgO-based sorbents", Journal of Materials Chemistry A, August 2020

[0006] The present disclosure provides a method for producing CO2 using magnesium oxide particles. ２ To provide a technology for improving the gas adsorption rate.

[0007] A coated nanocluster according to one embodiment of the present disclosure comprises a core containing an aggregate of magnesium oxide particles and a shell covering the core. The shell has a coating layer containing at least one of a nitrate and a nitrite, and carbonate particles dispersed in the coating layer. At least one of the nitrate and the nitrite contains an alkali metal ion. The carbonate particles contain at least one ion selected from calcium ions, strontium ions, and barium ions. The molar ratio of the carbonate particles constituting the shell to the magnesium oxide particles constituting the core is greater than 0.005 and less than or equal to 0.015.

[0008] According to one embodiment of the present disclosure, CO ２ The gas adsorption rate can be improved.

[0009] 1 is a cross-sectional view of a coated nanocluster according to one embodiment. ２ 3 is a diagram showing an example of a gas adsorption mechanism. ３ The nanocluster CO contains CO in the shell rather than the core. ２ 4 is a diagram showing the adsorption rate for each first molar ratio x1. ３ The nanoclusters contain CO in the core but not in the shell. ２ FIG. 5 is a diagram showing the adsorption rate for each second molar ratio x2. FIG. 5 is a flowchart showing a method for producing nanoclusters according to one embodiment. FIG. 6 is an SEM photograph showing an aggregate of precursor particles according to an example. FIG. 7 is a diagram showing an XRD diffraction pattern of an aggregate of precursor particles according to an example. FIG. 8 is an SEM photograph showing a nanocluster according to an example. FIG. 9 is a diagram showing an XRD diffraction pattern of a nanocluster according to an example. FIG. 10 is a diagram showing an XRD diffraction pattern of a nanocluster according to a reference example.

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In each drawing, identical or similar components are denoted by the same reference numerals, and their description may be omitted. In the specification, the symbol "to" indicating a range of values ​​means that the values ​​before and after it are included as the lower and upper limits. In the specification, particle size refers to the maximum Feret diameter (maximum projected width) when particles are observed with a scanning electron microscope (SEM).

[0011] A coated nanocluster 10 according to one embodiment will be described with reference to Figure 1. The nanocluster 10 comprises a core 20 and a shell 30 that covers the core 20. The core 20 includes an aggregate of magnesium oxide particles 21. The shape of the magnesium oxide particles 21 is not particularly limited, but may be, for example, scale-like. The average particle size of the magnesium oxide particles 21 is, for example, 1 nm to 1000 nm. The core 20 is in a block shape. The average particle size of the core 20 is, for example, 2 µm to 50 µm. The core 20 may also be composed of a single magnesium oxide particle 21.

[0012] The shell 30 need only cover at least a portion of the core 20, and does not have to completely cover the core 20. The shell 30 has a coating layer 31 containing at least one of a nitrate and a nitrite, and carbonate particles 32 dispersed in the coating layer 31. The coating layer 31 has an uneven shape that matches the surface of the core 20. At least one of the nitrate and the nitrite contains an alkali metal ion. The carbonate particles 32 contain at least one ion selected from calcium ions, strontium ions, and barium ions. The average particle size of the nanoclusters 10 is, for example, 2 μm to 50 μm.

[0013] The nanocluster 10 is CO ２ The adsorption property can be improved by forming the adsorbent into a compact. For example, the ... ２The pressure loss of the gas flow to be treated during adsorption can be reduced. Furthermore, the improved strength prevents the powder from scattering, improving fluidity. Pellets can be produced by using a pelletizer, compression molding, or extrusion molding. Granulation methods include rolling granulation, spray granulation, stirring granulation, fluidized bed granulation, and briquette granulation. Granulation aids such as granulation promoters or binders may be used during granulation.

[0014] The inventors of the present invention have demonstrated that the pressure is low and CO ２ CO from low concentration gas to nanocluster 10 ２ In order to efficiently adsorb calcium carbonate (CaCO ３ ), strontium carbonate (SrCO ３ ) or barium carbonate (BaCO ３ ) was added to the shell 30 instead of the core 20. As will be described in detail later, ３ The effect of adding the above to the shell 30 instead of the core 20 was confirmed by experiments.

[0015] Referring to FIG. ２ An example of a gas adsorption mechanism will be described. The shell 30 shown in FIG. 2 is made of CaCO ３ and SrCO ３ and BaCO ３ Of these, CaCO ３ The shell 30 contains only CaCO ３ and SrCO ３ and BaCO ３ The composition may contain at least one of the above, and may contain a plurality of the above. The combination thereof is not particularly limited.

[0016] As shown in Figure 2, CO contained in exhaust gas, etc. ２ After dissolving in the shell 30, carbonate ions (CO ３ ２－ ), followed by the formation of carbonate. At this time, the higher the carbonate ion concentration, the more likely the formation of carbonate will proceed.

[0017] Shell 30 is CaCO ３ By including CO ２and the formation of carbonate ions. ３ ) ２ As a result, the pressure is low and CO ２ CO from low concentration gas to nanocluster 10 ２ can be efficiently adsorbed.

[0018] The shell 30 is made of CaCO ３ and SrCO ３ and BaCO ３ In any case, it is sufficient to include at least one of the following: ２ Carbonate ions can be supplied to the shell 30 without waiting for the dissolution of CaMg(CO ３ ) ２ , SrMg(CO ３ ) ２ or BaMg(CO ３ ) ２ The formation of such a complex salt can have the effect of accelerating carbonate formation.

[0019] Figure 3 shows the CaCO ３ in the shell 30 but not in the core 20. ２ The adsorption rate is shown for each first molar ratio x1. In FIG. 3, the horizontal axis represents the rate at which the nanocluster 10 is adsorbed to a gas (CO ２ The vertical axis represents the time of exposure to a partial pressure of 0.15 bar, and the vertical axis represents the CO per unit mass of nanocluster 10. ２ The adsorption amount (mmol / g) is shown.

[0020] In FIG. 3, the first molar ratio x1 is the ratio of magnesium oxide (MgO) constituting the core 20 to CaCO 3 constituting the shell 30. ３ and SrCO ３ and BaCO ３ In FIG. 3, the shell 30 is a molar ratio of CaCO ３ and SrCO ３ and BaCO ３ Of these, CaCO ３ Contains only.

[0021] 3, the molar ratio of each nitrate and nitrite constituting the shell 30 to MgO constituting the core 20 is constant regardless of the first molar ratio x1. ３ The molar ratio of NaNO to MgO is 0.030. ３ The molar ratio of KNO to MgO is 0.018. ３ The molar ratio of is 0.052. In FIG. 3, the shell 30 contains only nitrate out of nitrate and nitrite.

[0022] From FIG. 3, when the first molar ratio x1 is greater than zero, the CO ２ In particular, when the first molar ratio x1 is greater than 0.005 and equal to or less than 0.015, the CO ２ It can be seen that the adsorption rate is fast. The conditions for producing the nanocluster 10 having the first molar ratio x1 shown in FIG.

[0023] CO shown in FIG. ２ The adsorption amount (mmol / g) was determined using a thermogravimetric analyzer (product name: SDT650) manufactured by TA Instruments. The temperature of the sample was raised to 300°C at a rate of 20°C / min, and then the gas described below was supplied at 100 mL / min while maintaining the temperature at 300°C, and the change in the weight of the sample was measured. The gas used was dry CO ２ and dry N ２ Mixture of gases (total pressure: 1.00 bar, CO ２ Partial pressure: 0.15 bar). ２ Before measuring the amount of adsorption, the atmospheric CO adsorbed on the sample was ２ and dried N ２ The sample was heated at 450° C. for 1 hour while supplying 100 mL / min of

[0024] Figure 4 shows the CaCO ３ in the core 20 but not in the shell 30. ２ The adsorption rate is shown for each second molar ratio x2. In FIG. 4, the horizontal axis represents the time when the nanocluster 10 is heated to 300° C. and gas (CO ２The vertical axis represents the time of exposure to a partial pressure of 0.15 bar, and the vertical axis represents the CO per unit mass of nanocluster 10. ２ The adsorption amount (mmol / g) is shown.

[0025] In FIG. 4, the second molar ratio x2 is the ratio of CaCO 3 constituting the core 20 to magnesium oxide (MgO) constituting the core 20. ３ and SrCO ３ and BaCO ３ In FIG. 4, the core 20 is a molar ratio of CaCO ３ and SrCO ３ and BaCO ３ Of these, CaCO ３ Contains only.

[0026] 4, the molar ratio of each nitrate and nitrite constituting the shell 30 to MgO constituting the core 20 is constant regardless of the second molar ratio x2. ３ The molar ratio of NaNO to MgO is 0.030. ３ The molar ratio of KNO to MgO is 0.018. ３ The molar ratio of nitrate to nitrite is 0.052. In FIG. 4, the shell 30 contains only nitrate out of the nitrate and nitrite.

[0027] From FIG. 4, when the second molar ratio x2 is greater than zero, the CO ２ It can be seen that the adsorption rate is fast. The method for producing the nanocluster 10 having the second molar ratio x2 shown in FIG. 4 will be described later. ２ The method for measuring the adsorption amount was the CO ２ The method is the same as the method for measuring the amount of adsorption, so the explanation will be omitted.

[0028] From Figures 3 and 4, CaCO ３ or the like is added to the shell 30 instead of the core 20 and the first molar ratio x1 is set to be greater than 0.005 and not greater than 0.015, CaCO ３ or the like is added to the core 20 instead of the shell 30. ２ It is clear that the adsorption rate can be improved.

[0029] The total content of components other than MgO in the core 20 is preferably 0 mol% to 10 mol%, more preferably 0 mol% to 5 mol%, and even more preferably 0 mol% to 1 mol%. The MgO content in the core 20 is preferably 90 mol% to 100 mol%, more preferably 95 mol% to 100 mol%, and even more preferably 99 mol% to 100 mol%.

[0030] That is, it is preferable that the core 20 is made of only MgO, excluding impurities that are inevitably mixed into the core 20 during the manufacturing process. ２ The equilibrium adsorption amount (mmol / g) can be increased. The equilibrium adsorption amount is the amount of adsorption when the adsorption rate and desorption rate become equal and the adsorption reaches equilibrium after a sufficient amount of time has passed. Examples of the other components include CaO, Al ２ O ３ , Fe ２ O ３ , SiO ２ , MgCl ２ , MgCO ３ , CaCO ３ , BaCO ３ , SrCO ３ , Mg ２ (OH) ２ CO ３ , MgCa(CO ３ ) ２ , MgSO ４ etc.

[0031] 5, a method for manufacturing nanocluster 10 according to one embodiment will be described. The method for manufacturing nanocluster 10 includes steps S101 to S105. Note that the method for manufacturing nanocluster 10 may include at least steps S104 to S105. The method for manufacturing nanocluster 10 may also include steps not shown. An example of a step not shown is a step of pulverizing the reaction product.

[0032] Step S101 includes precipitating an aggregate of precursor particles containing a precursor of magnesium oxide by reacting an aqueous magnesium salt solution with an aqueous base solution, thereby preparing a suspension containing a dispersed aggregate of the precursor particles. The precursor is, for example, basic magnesium carbonate (mMgCO ３ Mg(OH) ２ ・nH ２ O), where m is, for example, 3 to 5, and n is, for example, 3 to 7.

[0033] The magnesium salt aqueous solution is prepared by dissolving magnesium salt in pure water. The magnesium salt may be an inorganic acid salt or an organic acid salt. The inorganic acid salt may be, for example, magnesium chloride (MgCl ２ ), magnesium nitrate (Mg(NO ３ ) ２ ) or magnesium sulfate (MgSO ４ ) and the like. Organic acid salts include magnesium acetate (Mg(CH ３ COO) ２ The magnesium salt may be a hydrate.

[0034] The basic aqueous solution is, for example, sodium carbonate (Na ２ CO ３ ), sodium hydroxide (NaOH) or ammonium carbonate ((NH ４ ) ２ CO ３ ) in pure water. ２ CO ３ ) instead of potassium carbonate (K ２ CO ３ ) may also be used.

[0035] Step S101 may include precipitating an aggregate of precursor particles containing a magnesium oxide precursor by a reaction between magnesium hydroxide and carbon dioxide gas, thereby preparing a suspension containing an aggregate of precursor particles.

[0036] Step S102 includes separating the aggregates of precursor particles from the suspension. The separation method is not particularly limited, but may be, for example, a centrifugation method. The aggregates of precursor particles separated from the suspension are dried and then pulverized in a mortar or the like.

[0037] An aggregate of precursor particles is prepared by steps S101 and S102. The precursor may be any material that can be converted into magnesium oxide (MgO) by step S105 (calcination), such as magnesium hydroxide (Mg(OH) ２ ) or magnesium carbonate (MgCO ３ ) may be used. Alternatively, an aggregate of precursor particles containing a commercially available magnesium oxide precursor may be used. Note that an aggregate of magnesium oxide particles 21 may be prepared instead of the aggregate of precursor particles, and in that case, step S105 (firing) is not necessary.

[0038] Step S103 includes precipitating carbonate particles 32 by a reaction between a nitrate solution and a carbonate solution, thereby preparing a treatment liquid containing dispersed carbonate particles 32. The nitrate solution contains nitrate ions (NO ３ － ) and nitrite ions (NO ２ － The solvent for the nitrate solution is pure water in this embodiment, but it may also be an organic solvent such as methanol. On the other hand, the carbonate solution contains at least one of carbonate ions (CO ３ ２－ The solvent for the carbonate solution is pure water in this embodiment, but may be an organic solvent such as methanol.

[0039] The nitrate solution contains calcium ions (Ca ２＋ ) and strontium ions (Sr ２＋ ) and barium ions (Ba ２＋ The reaction between the nitrate solution and the carbonate solution causes the precipitation of carbonate particles 32. The carbonate particles 32 include Ca ２＋ and Sr ２＋ and Ba ２＋ Further, the present invention includes at least one selected from the following:

[0040] The treatment solution contains nitrate ions (NO ３ － ) and nitrite ions (NO ２ －) and alkali metal ions, and also contains dispersed carbonate particles 32. The solvent of the treatment liquid is pure water in this embodiment, but may be an organic solvent such as methanol. The solvent of the treatment liquid may be any solvent that can dissolve nitrate or nitrite and precipitate the nitrate or nitrite upon drying. The precipitated nitrate or nitrite constitutes the coating layer 31.

[0041] In step S103, a treatment liquid is prepared. The method for preparing the treatment liquid is not particularly limited. For example, the treatment liquid may be prepared by adding carbonate particles 32 to a nitrate solution. The treatment liquid may contain at least one of nitrate ions and nitrite ions and alkali metal ions, and may also contain dispersed carbonate particles 32.

[0042] Step S104 includes drying the aggregate of precursor particles in contact with a treatment liquid. For example, step S104 includes adding the aggregate of precursor particles to a treatment liquid and stirring the treatment liquid to prepare a dispersion. Thereafter, the dispersion is dried by heating, thereby obtaining an aggregate of precursor particles coated with a shell 30 (including the coating layer 31 and the carbonate particles 32). The aggregate of precursor particles coated with the shell 30 is pulverized in a mortar or the like.

[0043] Step S105 includes firing the aggregate of precursor particles coated with shell 30. The firing temperature is, for example, 400°C to 500°C. The firing atmosphere is, for example, air. Nanocluster 10 is obtained by step S105. As described above, nanocluster 10 includes core 20 including an aggregate of magnesium oxide particles 21 and shell 30 covering core 20.

[0044] In the method of manufacturing nanocluster 10 shown in FIG. 5, a treatment liquid is prepared and then the precursor particle aggregate is brought into contact with the treatment liquid. However, a nitrate solution, which is another material of the treatment liquid, may be reacted with the carbonate solution while the precursor particle aggregate is in contact with the carbonate solution. In either case, the precursor particle aggregate can be brought into contact with the treatment liquid. Then, the treatment liquid is dried to obtain a precursor particle aggregate coated with shell 30 (including coating layer 31 and carbonate particles 32).

[0045] Hereinafter, referring again to FIG. 5, the conditions for producing the nanoclusters shown in FIG. 3 in which the first molar ratio x1 is 0.010 will be described.

[0046] (Step S101) The magnesium salt aqueous solution is MgCl ２ It was an aqueous solution (concentration: 1 mol / L, volume: 100 mL). ２ The aqueous solution contained 20.33 g (100 mmol) of MgCl ２ ・6H ２ It was prepared by dissolving O in pure water.

[0047] The basic aqueous solution is Na ２ CO ３ It was an aqueous solution (concentration: 1 mol / L, volume: 100 mL). ２ CO ３ The aqueous solution contained 10.60 g (100 mmol) of Na ２ CO ３ was prepared by dissolving in pure water.

[0048] MgCl ２ Aqueous solution and Na ２ CO ３ The reaction with aqueous solution is ２ The aqueous solution was stirred at 25°C, and Na ２ CO ３ The aqueous solution was added dropwise in an amount of 100 mL at a rate of 10 mL / min, resulting in a white suspension (volume: 200 mL).

[0049] (Step S102) The resulting white suspension was separated into a precipitate and a supernatant by centrifugation. The precipitate remaining after removing the supernatant was dispersed in pure water and then centrifuged again to separate the precipitate and the supernatant. This process (dispersion in pure water and centrifugation) was repeated five times.

[0050] The precipitate was then dried in a muffle furnace at 120°C in an air atmosphere for 6 hours and then crushed in an agate mortar. 9.35 g of powder was obtained. The resulting powder was an aggregate of scaly precursor particles, as shown in Figure 6. The aggregate was in the form of clumps.

[0051] The components constituting the obtained powder were identified by the XRD diffraction pattern as shown in FIG. ３ Mg(OH) ２ ・4H ２ It was O.

[0052] (Step S103) The nitrate solution (volume: 4 mL) contains 0.0531 g (0.77 mmol) of LiNO ３ and 0.0393 g (0.46 mmol) of NaNO ３ and 0.1349 g (1.33 mmol) of KNO ３ and 0.0757 g (0.32 mmol) of Ca(NO ３ ) ２ ・4H ２ It was prepared by dissolving O in pure water.

[0053] The carbonate solution (volume: 4 mL) contained 0.0071 g (0.096 mmol) of Li ２ CO ３ and 0.0061 g (0.058 mmol) of Na ２ CO ３ and 0.0231 g (0.167 mmol) of K ２ CO ３ was prepared by dissolving in pure water.

[0054] The reaction between the nitrate solution and the carbonate solution was carried out by adding 4 mL of the carbonate solution dropwise at a rate of 0.4 mL / min while stirring the nitrate solution at 25°C. As a result, a treated solution (volume: 8 mL) was obtained. The treated solution contained nitrate ions (NO３ － ) and alkali metal ions, and CaCO ３ It contained dispersed particles.

[0055] (Step S104) The liquid contact is a treatment liquid (volume: 8 mL) containing basic magnesium carbonate (4MgCO ３ Mg(OH) ２ ・4H ２ 3 g (6.42 mmol) of powder of HCl (O) was added and stirred for 1 hour at 25° C. The resulting dispersion was dried in a muffle furnace at 120° C. in an air atmosphere for 16 hours, and then pulverized in an agate mortar.

[0056] (Step S105) The powder obtained in step S104 was fired by heating it in an air atmosphere at 450°C for 4 hours using a muffle furnace, crushing it in an agate mortar, and then heating it again in an air atmosphere at 450°C for 1 hour using a muffle furnace. Then, the powder obtained was crushed again in the agate mortar.

[0057] The powder obtained in step S105, i.e., the coated nanocluster 10, was in the form of clumps as shown in Figure 8. The components constituting the obtained powder were identified by the XRD diffraction pattern as shown in Figure 9, and were found to be MgO, nitrates, and CaCO ３ It was.

[0058] Table 1 shows the molar ratios of nitrate and carbonate used as raw materials for nanoclusters in which the first molar ratio x1 shown in FIG.

[0059]

[0060] The conditions for producing nanoclusters in which the first molar ratio x1 is 0.000, 0.005, 0.030, and 0.050 are the same as the conditions for producing nanoclusters in which the first molar ratio x1 is 0.010, except for the conditions shown in Table 1, and therefore a description thereof will be omitted.

[0061] 4, the conditions for producing the nanocluster in which the second molar ratio x2 is 0.010 are described below. In order to add the alkaline earth metal carbonate to the core 20 rather than the shell 30, a mixed aqueous solution of magnesium salt and calcium salt was used instead of the magnesium salt aqueous solution in step S101, and only a nitrate solution was used as the treatment liquid in step S103.

[0062] (Step S101) A mixed aqueous solution of magnesium salt and calcium salt (volume: 100 mL) contains 20.13 g (99 mmol) of MgCl ２ ・6H ２ O and 0.11 g (0.99 mmol) of CaCl ２ was prepared by dissolving in pure water.

[0063] The basic aqueous solution is Na ２ CO ３ It was an aqueous solution (concentration: 1 mol / L, volume: 100 mL). ２ CO ３ The aqueous solution contained 10.60 g (100 mmol) of Na ２ CO ３ was prepared by dissolving in pure water.

[0064] MgCl ２ Aqueous solution and Na ２ CO ３ The reaction with aqueous solution is ２ and CaCl ２ The mixed aqueous solution of Na ２ CO ３ The aqueous solution was added dropwise in an amount of 100 mL at a rate of 10 mL / min, resulting in a white suspension (volume: 200 mL).

[0065] (Step S102) The resulting white suspension was separated into a precipitate and a supernatant by centrifugation. The precipitate remaining after removing the supernatant was dispersed in pure water and then centrifuged again to separate the precipitate and the supernatant. This process (dispersion in pure water and centrifugation) was repeated five times. The precipitate was then dried in a muffle furnace at 120°C in air for 6 hours and then pulverized in an agate mortar. This yielded 9.36 g of powder.

[0066] (Step S103) The treatment liquid was a nitric acid solution (volume: 8 mL). The nitrate solution contained 0.0656 g (0.952 mmol) of LiNO ３ and 0.0486 g (0.571 mmol) of NaNO ３ and 0.167 g (1.65 mmol) of KNO ３ The treatment solution was prepared by dissolving the above in pure water. ３ － ) and alkali metal ions, but CaCO ３ It was particle free.

[0067] (Step S104) The liquid contact was performed by adding 3 g of the powder obtained in step S102 to the treatment liquid (volume: 8 mL) and stirring for 1 hour at 25° C. The obtained dispersion was dried in a muffle furnace at 120° C. in an air atmosphere for 16 hours, and then pulverized in an agate mortar.

[0068] (Step S105) The powder obtained in step S104 was fired by heating it in an air atmosphere at 450°C in a muffle furnace for 4 hours, pulverizing it in an agate mortar, and then heating it again in an air atmosphere at 450°C in a muffle furnace for 1 hour. The powder obtained was then pulverized again in the agate mortar. The components constituting the obtained powder were identified by the XRD diffraction pattern as shown in Figure 10, and were found to be MgO, nitrates, and CaCO ３ It was.

[0069] CaCl used as a raw material for nanoclusters with the second molar ratio x2 of 0.000, 0.005, 0.010, 0.030, and 0.050 shown in FIG. ２ The molar ratio of nitrate to ammonium hydroxide is shown in Table 2.

[0070]

[0071] The conditions for producing nanoclusters in which the second molar ratio x2 is 0.000, 0.005, 0.030, and 0.050 are the same as those for producing nanoclusters in which the second molar ratio x2 is 0.010, except for the conditions shown in Table 2, and therefore a description thereof will be omitted.

[0072] The coated nanoclusters and methods for producing the same according to the present disclosure have been described above, but the present disclosure is not limited to the above embodiments. Various changes, modifications, substitutions, additions, deletions, and combinations are possible within the scope of the claims. These naturally fall within the technical scope of the present disclosure.

[0073] According to the present invention, the CO ２ It is possible to provide a technology that improves the gas adsorption rate.

[0074] 10 nanocluster 20 core 21 magnesium oxide particle 30 shell 31 coating layer 32 carbonate particle

Claims

1. A coated nanocluster comprising a core containing an aggregate of magnesium oxide particles and a shell covering the core, wherein the shell has a coating layer containing at least one of a nitrate and a nitrite, and carbonate particles dispersed in the coating layer, wherein at least one of the nitrate and the nitrite contains an alkali metal ion, and the carbonate particles contain at least one selected from calcium ions, strontium ions, and barium ions, and wherein the molar ratio of the carbonate particles constituting the shell to the magnesium oxide particles constituting the core is greater than 0.005 and not greater than 0.

015.

2. The nanocluster of claim 1, wherein the core has a magnesium oxide content of 90 mol % to 100 mol %.

3. A method for producing the nanocluster according to claim 1 or 2, comprising the steps of: bringing an aggregate of precursor particles containing a magnesium oxide precursor into contact with a treatment liquid containing at least one of nitrate ions and nitrite ions and alkali metal ions, and containing dispersed carbonate particles, and drying the aggregate of precursor particles that have been brought into contact with the treatment liquid and dried.

4. A method for producing nanoclusters according to claim 3, comprising: precipitating aggregates of precursor particles by a reaction between an aqueous magnesium salt solution and a basic aqueous solution, thereby preparing a suspension containing dispersed aggregates of precursor particles; and separating the aggregates of precursor particles from the suspension.

5. A method for producing nanoclusters as described in claim 3, comprising precipitating the carbonate particles by a reaction between a nitrate solution and a carbonate solution, and preparing the treatment liquid containing the carbonate particles dispersed therein, wherein the nitrate solution contains at least one of nitrate ions and nitrite ions and alkali metal ions, and further contains at least one selected from calcium ions, strontium ions and barium ions, and the carbonate solution contains carbonate ions and alkali metal ions.

6. A method for producing nanoclusters according to claim 1 or 2, comprising contacting an aggregate of magnesium oxide particles with a treatment liquid containing at least one of nitrate ions and nitrite ions, and alkali metal ions, and containing dispersed carbonate particles, and then drying the aggregate.

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