Adsorbent

Abstract

To provide a novel adsorbent that has a high adsorption capacity and that is capable of adsorbing a target material with a small amount of use.SOLUTION: The present disclosure provides an adsorbent composed of an amorphous magnesium silicate compound. The magnesium silicate compound according to the present disclosure has an alkali metal content of 1.20 mass% or less. The magnesium silicate compound according to the present disclosure has a solid acid content of 0.70 mmol / g or more.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to a novel adsorbent used for adsorbing substances such as alkali metals. [Background technology]

[0002] Chemical products may contain trace amounts of impurities, such as catalysts used during synthesis, unreacted raw materials, and by-products from the reaction. From the perspective of improving product quality, it is necessary to efficiently remove these impurities. Methods for removing such impurities include neutralization, distillation, extraction, or adsorption during the chemical product manufacturing process. Among these, adsorption, particularly methods using adsorbents, is a commonly used and convenient method.

[0003] For example, polyurethane foam is manufactured by polymerizing polyol and isocyanate components, which are the raw materials. Polyols used in the manufacture of polyurethane foam include polyether polyols, polymer polyols, and polyester polyols, and are used in any combination according to the desired performance of the polyurethane. For example, polyether polyols are manufactured by addition polymerization of propylene oxide to glycerin in the presence of an alkali metal-containing basic catalyst, but a purity of as close to zero residual catalyst as possible is required after purification.

[0004] To achieve such a high level of purity, adsorbents capable of adsorbing and removing alkali metal-containing basic catalysts are used in the production of polyether polyols. The adsorbents used here are typically synthetic products such as molecular sieves, activated alumina, synthetic magnesium silicate, synthetic aluminum silicate, and activated carbon; natural products; and processed natural products such as acid clay and activated clay, but are not particularly limited. For example, Patent Document 1 discloses an adsorbent consisting of an amorphous synthetic hydrated magnesium silicate compound, in which the chemical formula, BET specific surface area, alkali metal content, and average particle size are all within specific ranges, as an adsorbent capable of adsorbing and removing alkali metal-containing basic catalysts. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2004-75674 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] However, these conventional adsorbents require a large amount of adsorbent relative to the alkali metal-containing basic catalyst being adsorbed, leading to problems such as reduced yield due to the adsorption of polyether polyols onto the adsorbent and the generation of large amounts of waste after purification. To solve these problems, there is a strong need to improve the adsorption capacity of adsorbents and reduce the amount of adsorbent used.

[0007] Therefore, the present invention aims to provide a novel adsorbent that has high adsorption capacity and can adsorb substances with a small amount of use. [Means for solving the problem]

[0008] The inventors of the present invention conducted diligent studies to achieve the above objective and found that by using an amorphous magnesium silicate compound with a low alkali metal content and high solid acidity as an adsorbent, K + kaNa+ , Ni + It has been found that the adsorption ability for metal ions such as etc. is improved. The present disclosure has been completed based on such findings and includes the following aspects.

[0009] (First disclosure) This first disclosure is an adsorbent composed of an amorphous magnesium silicate compound. The magnesium silicate compound has an alkali metal content of 1.20% by mass or less. The magnesium silicate compound has a solid acid amount of 0.70 mmol / g or more.

[0010] (Second disclosure) In this second disclosure, in the first disclosure, the magnesium silicate compound is a compound represented by the following formula (1). (MgO) x ·SiO2·mH2O ···(1) [In formula (1), x is a number satisfying 0.1 ≦ x ≦ 0.5. m is a number satisfying 0.1 ≦ m ≦ 1.5.]

[0011] (Third disclosure) In this third disclosure, in the first disclosure or the second disclosure, the BET specific surface area of the magnesium silicate compound is 200 m 2 / g to 1000 m 2 / g.

[0012] (Fourth disclosure) In this fourth disclosure, in any one of the first disclosure to the third disclosure, the total pore volume of the magnesium silicate compound is 0.40 cm 3 / g to 1.50 cm 3 / g.

[0013] (Fifth disclosure) This fifth disclosure is a method for reducing the alkali metal content in polyether polyol. The reduction method includes contacting a polyether polyol containing an alkali metal-containing basic catalyst with an adsorbent according to any one of the first disclosure to the fourth disclosure. [Effects of the invention]

[0014] According to the present invention, it is possible to provide a novel adsorbent having a high adsorption capacity and capable of adsorbing an adsorbed substance with a small amount of use.

Brief Description of the Drawings

[0015] [Figure 1] FIG. 1 is an X-ray diffraction pattern of the magnesium silicate compound of Example 2 by the powder method. [Figure 2] FIG. 2 is an X-ray diffraction pattern of the magnesium silicate compound of Example 4 by the powder method.

Modes for Carrying Out the Invention

[0016] Hereinafter, preferred embodiments of the adsorbent of the present invention will be described in detail. In this specification, various numerical ranges mean ranges including their upper and lower limit values unless otherwise specified.

[0017] [Adsorbent] The adsorbent according to one embodiment of the present invention is composed of an amorphous magnesium silicate compound. This magnesium silicate compound has an alkali metal content of 1.20% by mass or less. Further, this magnesium silicate compound has a solid acid amount of 0.70 mmol / g or more.

[0018] The adsorbent of this embodiment is composed of an amorphous magnesium silicate compound having a low alkali metal content and a high solid acidity as described above, so that K + , Na + , Ni +It can exhibit excellent adsorption capacity for metal ions such as [specific metal ions]. Furthermore, its adsorption capacity is significantly higher than that of conventional adsorbents made of magnesium silicate compounds, so the amount of adsorbent used in this embodiment can be greatly reduced compared to such conventional adsorbents. In other words, the adsorbent of this embodiment is a novel adsorbent that has a much higher adsorption capacity than conventional adsorbents made of magnesium silicate compounds and can adsorb substances with a small amount of use. In addition, the adsorbent of this embodiment has the advantage of being able to contribute to the reduction of energy consumption and waste treatment, and can contribute to the achievement of the SDGs (Sustainable Development Goals) adopted at the UN Summit.

[0019] (Magnesium silicate compound) The adsorbent according to one embodiment of the present invention consists of an amorphous magnesium silicate compound as described above. Here, "amorphous magnesium silicate compound" means a magnesium silicate compound whose powder X-ray diffraction pattern is amorphous.

[0020] (Alkali metal content) In this embodiment, the alkali metal content of the magnesium silicate compound is 1.20% by mass or less.

[0021] Such alkali metal content below a specific amount can be achieved, for example, by adjusting the pH of the reaction slurry to be low during the synthesis of the magnesium silicate compound described later, or by performing heat aging treatment and / or acid treatment after synthesis. For example, the alkali metal content can be reduced by lowering the pH of the reaction slurry during the synthesis of the magnesium silicate compound. Furthermore, it is thought that performing heat aging treatment after the synthesis of the magnesium silicate compound can reduce the alkali metal content by promoting the dissolution and extraction of the magnesium silicate compound. In addition, performing acid treatment after the synthesis of the magnesium silicate compound can reduce the alkali metal content because the contained alkali metal components are replaced by protons from the acid.

[0022] In this specification, alkali metal components refer to alkali metals such as sodium and potassium derived from the raw materials.

[0023] The alkali metal content of the magnesium silicate compound is preferably 1.10% by mass or less, and more preferably 1.00% by mass or less. The lower limit of the alkali metal content of the magnesium silicate compound is not particularly limited, but for example, it is 0.001% by mass.

[0024] (solid acid amount) Furthermore, in one embodiment of the present invention, the solid acid content of the magnesium silicate compound is 0.70 mmol / g or more.

[0025] Such amounts of solid acid exceeding a specific amount can be obtained by the same means as described above for alkali metal content. That is, such amounts of solid acid exceeding a specific amount can be obtained, for example, by adjusting the pH of the reaction slurry to be low during the synthesis of the magnesium silicate compound described later, or by performing a heat aging treatment and / or acid treatment after synthesis. For example, by lowering the pH of the reaction slurry during the synthesis of the magnesium silicate compound, the alkali metal content can be reduced and the amount of solid acid can be increased. Furthermore, it is thought that performing a heat aging treatment after the synthesis of the magnesium silicate compound can reduce the alkali metal content and increase the amount of solid acid by promoting the dissolution and extraction of the magnesium silicate compound. Also, by performing an acid treatment after the synthesis of the magnesium silicate compound, the contained alkali metal components are replaced by acid protons, thus reducing the alkali metal content and increasing the amount of solid acid.

[0026] The solid acid content of the magnesium silicate compound is preferably 1.00 mmol / g or more, and more preferably 1.50 mmol / g or more. The upper limit of the solid acid content of the magnesium silicate compound is not particularly limited, but an example is 10.00 mmol / g.

[0027] The specific method for measuring the amount of solid acid will be explained in the examples below.

[0028] Thus, the magnesium silicate compound in one embodiment of the present invention has an alkali metal content of less than or equal to the specified amount and a high solid acid content of more than or equal to the specified amount, thereby exhibiting excellent adsorption capacity for various metal ions. As a result, the adsorbent of this embodiment can adsorb various metal ions with a smaller amount than adsorbents made of conventional magnesium silicate compounds.

[0029] (chemical formula) In this embodiment, the magnesium silicate compound is amorphous, has an alkali metal content of less than or equal to the specified amount, and has a high solid acid content of more than or equal to the specified amount, but it is preferably a hydrated magnesium silicate compound represented by the following formula (1). (MgO) x ·SiO2·mH2O ···(1) [In equation (1), x is a number satisfying 0.1 ≤ x ≤ 0.5, and m is a number satisfying 0.1 ≤ m ≤ 1.5.]

[0030] If the magnesium silicate compound is a hydrated magnesium silicate compound represented by formula (1), it can more reliably exhibit the excellent adsorption capacity for the aforementioned metal ions.

[0031] In addition, in equation (1) above, the preferred range for x is 0.2 ≤ x ≤ 0.35.

[0032] (BET specific surface area) In this embodiment, the BET specific surface area of ​​the magnesium silicate compound is 200 m². 2 / g~1000m 2 It is preferable that the BET specific surface area of ​​the magnesium silicate compound is within this range, which ensures a certain level of adsorption, and thus allows it to more reliably exhibit the excellent adsorption capacity for the metal ions mentioned above.

[0033] The BET specific surface area of ​​magnesium silicate compounds is 220 m². 2 It is more preferable that it be 250m or more per gram. 2 It is even more preferable that the amount is 1 / g or more. Furthermore, the BET specific surface area of ​​the magnesium silicate compound is 900 m². 2 It is more preferable that it be less than / g, and 800m 2 It is even more preferable that the amount be less than or equal to / g.

[0034] In this specification, BET specific surface area refers to the specific surface area of ​​a magnesium silicate compound measured by the BET method. The specific method for measuring the BET specific surface area will be described in the examples below.

[0035] (Total pore volume) In this embodiment, the total pore volume of the magnesium silicate compound is 0.40 cm³. 3 / g~1.50cm 3 It is preferable that the amount is / g. When the total pore volume of the magnesium silicate compound is within this range, a certain amount of adsorption can be ensured, and thus the excellent adsorption capacity for the metal ions mentioned above can be more reliably demonstrated.

[0036] The total pore volume of the magnesium silicate compound is 0.50 cm³. 3 It is more preferable that the amount is 1 / g or more. Furthermore, the total pore volume of the magnesium silicate compound is 1.20 cm³. 3 It is more preferable that the value be less than or equal to / g.

[0037] The specific method for measuring the total pore volume will be explained in the examples below.

[0038] (Average particle size) Furthermore, in this embodiment, it is preferable that the average particle size of the magnesium silicate compound is between 2.0 μm and 60.0 μm. When the average particle size of the magnesium silicate compound is within this range, the specific surface area can be increased, ensuring a certain level of adsorption, and thus the excellent adsorption capacity for metal ions described above can be more reliably demonstrated.

[0039] The average particle size of the magnesium silicate compound is more preferably 5.0 μm or larger. Furthermore, the average particle size of the magnesium silicate compound is more preferably 50.0 μm or smaller.

[0040] The specific method for measuring the average particle size will be explained in the examples below.

[0041] [Manufacturing method] The following describes a method for producing a magnesium silicate compound constituting an adsorbent according to one embodiment of the present invention, using the above-described method for producing a hydrated magnesium silicate compound as an example. The magnesium silicate compound that can be used as an adsorbent in the present invention is amorphous, has an alkali metal content of less than or equal to the specified amount, and has a high solid acid content of more than or equal to the specified amount; however, the method of production and conditions are not limited in any way.

[0042] (synthesis process) The above-mentioned hydrated magnesium silicate compounds can be synthesized by reacting a water-soluble magnesium compound with a water-soluble silicate compound. Examples of water-soluble magnesium compounds include magnesium chloride, magnesium sulfate, and magnesium nitrate. Examples of water-soluble silicate compounds include alkali silicates such as sodium silicate, sodium metasilicate, sodium orthosilicate, and potassium silicate, which are commonly known as water glass and have the general formula Na2O·nSiO2 (n=2~4). Among these, it is preferable to use No. 3 water glass as the water-soluble silicate compound.

[0043] The reaction may be a batch reaction in which a fixed amount of magnesium compound aqueous solution and a fixed amount of silicate compound aqueous solution are simultaneously poured into a reaction vessel, or it may be a continuous reaction in which a fixed amount of magnesium compound aqueous solution and a fixed amount of silicate compound aqueous solution are continuously poured into the reaction vessel to continuously obtain a reaction slurry. From the standpoint of production efficiency, the continuous reaction is advantageous.

[0044] The reaction temperature is not particularly limited, but for example, a temperature of 15°C to 60°C can be used. For example, the reaction vessel may be placed in a constant temperature bath controlled to a constant temperature and carried out the reaction, or a container containing an aqueous solution of a magnesium compound and a container containing an aqueous solution of a silicate compound may be placed in a constant temperature bath controlled to a constant temperature, and the solutions from each container may be poured into the reaction vessel using a metering pump.

[0045] The reaction pH is, for example, 7 to 10, preferably 8.5 to 9.5. By adjusting the reaction pH within this range, the primary particles of the synthesized hydrated magnesium silicate compound can be made into fine particles. By making the primary particles into fine particles, the specific surface area of ​​the hydrated magnesium silicate compound increases, increasing the adsorption sites and improving the adsorption capacity.

[0046] (heat aging process) The reaction slurry obtained by the above synthesis process may be aged by heating and stirring. The aging temperature is, for example, 60°C to 120°C, preferably 70°C to 110°C, and more preferably 80°C to 100°C. The aging time is, for example, 0.5 hours to 18 hours, preferably 1 hour to 12 hours, and more preferably 2 hours to 6 hours. By heating and aging the synthesized hydrated magnesium silicate compound under these specific conditions, the specific surface area of ​​the hydrated magnesium silicate compound increases, the number of adsorption sites increases, and the adsorption capacity can be improved.

[0047] (Acid treatment process) The synthesized hydrated magnesium silicate compound may be treated with an inorganic acid. Such treatment replaces the alkali metal components in the synthesized hydrated magnesium silicate compound with protons from the inorganic acid, increasing the solid acidity of the compound and thus improving its adsorption capacity for alkali metal ions. The alkali metal components may include, for example, sodium or potassium derived from the raw materials.

[0048] The inorganic acids that can be used in the acid treatment process are not particularly limited, but examples include sulfuric acid, hydrochloric acid, and nitric acid.

[0049] Specific methods for the acid treatment process, that is, specific methods for replacing the alkali metal components in the synthesized hydrated magnesium silicate compound with protons from an inorganic acid, include, for example, a method of separating the reaction slurry into solid and liquid components, washing the solids with a diluted inorganic acid, and then rinsing with water. Other methods include separating the reaction slurry into solid and liquid components, suspending the solids in a diluted inorganic acid, stirring for a certain period of time, dehydrating, and then rinsing with water.

[0050] The concentration of the inorganic acid is, for example, 0.01 mol / L to 0.5 mol / L, preferably 0.02 mol / L to 0.2 mol / L. When the concentration of the diluted inorganic acid is 0.01 mol / L or higher, the substitution of protons in the inorganic acid with alkali metal components is sufficiently carried out. On the other hand, when the concentration of the diluted inorganic acid is 0.5 mol / L or lower, sulfate ions, chloride ions, nitrate ions, etc. of the inorganic acid are less likely to remain as impurities in the solid. Also, when the concentration of the diluted inorganic acid is 0.5 mol / L or lower, the magnesium in magnesium silicate is less likely to dissolve due to the inorganic acid.

[0051] (drying process) There are no particular limitations on the drying method for the hydrated magnesium silicate compound after synthesis, but one example is the shelf drying method, in which the dehydrated solid is placed in a stainless steel tray and dried with hot air. Other drying methods include the spray drying method, in which the dehydrated solid is slurryed to a concentration of 100 g / L to 500 g / L in terms of solid content, and if necessary, processed with a wet pulverizer such as a ball mill, colloid mill, SC mill, or Dyno mill to adjust the shape of the dried product, and then dried with a spray dryer. The spray drying method is preferable because it makes it easy to granulate the hydrated magnesium silicate compound into a spherical shape. Granulating the hydrated magnesium silicate compound into a spherical shape has the advantage of making it easier to separate and remove after adsorption treatment.

[0052] The magnesium silicate compound obtained by the above manufacturing method is amorphous, has an alkali metal content of less than or equal to the specified amount, and has a high solid acid content of more than or equal to the specified amount, depending on the reaction conditions during synthesis and the post-synthesis heating and / or acid treatment process.

[0053] Such magnesium silicate compounds can be used as adsorbents in various industrial applications, but as mentioned above, they are particularly useful as adsorbents for adsorbing and removing alkali metal-containing basic catalysts when producing polyether polyols.

[0054] [Method for reducing alkali metal content in polyether polyols] Another embodiment of the present invention is a method for reducing the alkali metal content in a polyether polyol. This reduction method involves contacting a polyether polyol containing an alkali metal-containing basic catalyst with an adsorbent consisting of an amorphous magnesium silicate compound having an alkali metal content of less than or equal to the specified amount and a high solid acid content of more than or equal to the specified amount.

[0055] As described above, this reduction method has excellent adsorption capacity, allowing it to adsorb various metal ions with a small amount of adsorbent. Therefore, it can increase the yield of polyether polyols and further reduce the amount of waste generated after purification.

[0056] Specific methods for adsorbing and removing residual alkali metal-containing basic catalysts contained in polyether polyols include, for example, adding the above-mentioned magnesium silicate compound as an adsorbent to the polyether polyol, mixing it, and then separating and removing the adsorbent.

[0057] The amount of adsorbent added depends on the amount of residual alkali metal-containing basic catalyst, but is, for example, 0.1% to 10.0% by mass relative to the mass of the polyether polyol, preferably 0.5% to 5.0% by mass.

[0058] For example, the adsorption treatment can be carried out under conditions of stirring, with a treatment temperature of 70°C to 150°C and a treatment time of 5 to 120 minutes. Water may be added during the adsorption treatment. In that case, it is preferable to add 0.5% to 3.0% by mass of water relative to the mass of the polyether polyol. Before the adsorption treatment, an antioxidant may be added to the polyether polyol to prevent degradation.

[0059] Alternatively, before adding the adsorbent to the polyether polyol, at least one of the inorganic acids, inorganic acid salts, and organic acids such as phosphoric acid, sulfuric acid, sodium hydrogen pyrophosphate, and oxalic acid may be added to induce a neutralization reaction. In this case, the adsorbent is added after the neutralization reaction is complete.

[0060] The present invention is not limited to the embodiments described above or the examples described later, and can be appropriately combined, substituted, or modified without departing from the purpose or spirit of the present invention. [Examples]

[0061] Hereinafter, the present invention will be described more specifically by way of examples of Examples and Comparative Examples, but the present invention is not limited only to these Examples.

[0062] Note that the measurement methods for various physical properties and the like regarding the Examples and Comparative Examples are as follows.

[0063] <SiO2 / MgO molar ratio and alkali metal content> The SiO2 / MgO molar ratio and alkali metal content of the magnesium silicate compound were measured using a scanning fluorescence X-ray analyzer "ZSX Primus IV" manufactured by Rigaku Corporation.

[0064] <BET specific surface area and total pore volume> The BET specific surface area and total pore volume of the magnesium silicate compound were measured using a high-precision specific surface area and pore size distribution measuring device "BELsorp-max" manufactured by MicrotracBEL Corporation.

[0065] <Liquid pH> The liquid pH of the magnesium silicate compound was measured as follows. 2.0 g of the dried magnesium silicate compound and 40 mL of ion-exchanged water were placed in a beaker and stirred with a magnetic stirrer for 5 minutes. Then, it was filtered using No. 5C filter paper, and the pH of the filtrate was measured. The pH of this filtrate was taken as the liquid pH of the magnesium silicate compound.

[0066] <Amount of solid acid> 0.1 g of dried magnesium silicate compound was placed in a stoppered Erlenmeyer flask, and 5 mL of benzene (Wako reagent grade) was added. 1 mL of a 0.1 wt% benzene solution of methyl orange, used as a pKa=4.8 indicator, was added, causing the dried particles to turn red. The mixture was titrated with a 0.1 mol / L n-butylamine-benzene solution until the dried particles turned yellow, and the amount of n-butylamine-benzene solution used for titration was denoted as A (mL). The Erlenmeyer flask was stoppered and allowed to stand for 24 hours, after which the dried particles returned to red. The mixture was then titrated again with a 0.1 mol / L n-butylamine-benzene solution until the dried particles turned yellow, and the amount of n-butylamine-benzene solution used for titration was denoted as B (mL). This procedure was repeated one more time, and the amount of n-butylamine-benzene solution used for titration was denoted as C (mL). The amount of solid acid was calculated from the total amount of titrations for the three titrations based on the following formula. Solid acid amount (mmol / g)=0.1(A+B+C) / 0.1g

[0067] <Average particle size> The average particle size of the magnesium silicate compound was measured using the "MICROTRAC MT3000II series" particle size distribution analyzer manufactured by Nikkiso Co., Ltd. Specifically, 0.7 g of dried magnesium silicate compound was first mixed with 70 mL of a 2.0 g / L sodium hexametaphosphate aqueous solution and stirred with a magnetic stirrer. 2 to 4 mL of this dispersion was then added to a 2.0 g / L sodium hexametaphosphate aqueous solution, and the dispersion was circulated for 1 minute. The particle size distribution was then measured using the aforementioned particle size distribution analyzer. The average particle size was determined from the obtained 50% cumulative (median diameter).

[0068] Next, examples and comparative examples of the present invention will be described.

[0069] Example 1 (Synthesis test) A 1.17 mol / L aqueous magnesium sulfate solution and a No. 3 aqueous solution consisting of 0.46 mol / L Na2O and 1.44 mol / L SiO2 were continuously added in a constant amount to a continuous reaction vessel to induce a coprecipitation reaction. The reaction temperature was 40°C. The pH of the resulting reaction slurry was 8.9. The average particle size of the reactant particles was 8.2 μm. Furthermore, this reaction slurry was dewatered by suction filtration using a Nutsche filter, and the resulting solid was washed with 20 times the weight of the solid in ion-exchanged water. The resulting solid was made into a slurry with a concentration of 250 g / L and spray-dried using a spray dryer.

[0070] The dried magnesium silicate compound of Example 1 obtained in this manner was subjected to various physical properties. As a result, the SiO2 / MgO molar ratio of the magnesium silicate compound of Example 1 was 3.5. The alkali metal content of the magnesium silicate compound of Example 1 was 1.00% by mass. The BET specific surface area of ​​the magnesium silicate compound of Example 1 was 295 m². 2 The concentration was / g. The total pore volume of the magnesium silicate compound in Example 1 was 0.47 cm³. 3 The concentration was / g. Furthermore, the pH of the magnesium silicate compound in Example 1 was 9.8. The solid acid content of the magnesium silicate compound in Example 1 was 0.73 mmol / g. The average particle size of the magnesium silicate compound in Example 1 was 42.2 μm. In addition, the powder X-ray diffraction pattern of the magnesium silicate compound in Example 1 showed that it was amorphous.

[0071] (Adsorption test 1) 160 g of polypropylene glycol (degree of polymerization: 3,000) in which potassium hydroxide was dissolved to a potassium concentration of 1400 ppm was placed in a four-necked round-bottom flask and heated and stirred with a mantle heater while purging with nitrogen. When the liquid temperature reached 85°C, 1.6 mL of deionized water was added, and then, after the liquid temperature reached 90°C, 0.4 g of an adsorbent consisting of a synthesized magnesium silicate compound was added, and the mixture was heated and stirred for 30 minutes. After 30 minutes, the treated solution was immediately filtered by suction at a suction pressure of 0.02 MPa to obtain the filtrate. The potassium concentration in this filtrate was determined to be 209 ppm by potentiometric titration with 0.01 N hydrochloric acid.

[0072] (Adsorption test 2) 160 g of polypropylene glycol (degree of polymerization: 3,000) in which potassium hydroxide was dissolved to a potassium concentration of 1400 ppm was placed in a four-necked round-bottom flask and heated and stirred with a mantle heater while purging with nitrogen. When the liquid temperature reached 85°C, 1.6 mL of deionized water was added, and then, after the liquid temperature reached 90°C, 0.56 g of an adsorbent consisting of a synthesized magnesium silicate compound was added, and the mixture was heated and stirred for 30 minutes. After 30 minutes, the treated solution was immediately filtered by suction at a suction pressure of 0.02 MPa to obtain the filtrate. The potassium concentration in this filtrate was determined to be 128 ppm by potentiometric titration with 0.01 N hydrochloric acid.

[0073] (Adsorption test 3) 160 g of polypropylene glycol (degree of polymerization: 3,000) in which potassium hydroxide was dissolved to a potassium concentration of 1400 ppm was placed in a four-necked round-bottom flask and heated and stirred with a mantle heater while purging with nitrogen. When the liquid temperature reached 85°C, 1.6 mL of deionized water was added, and then, after the liquid temperature reached 90°C, 0.8 g of an adsorbent consisting of a synthesized magnesium silicate compound was added, and the mixture was heated and stirred for 30 minutes. After 30 minutes, the treated solution was immediately filtered by suction at a suction pressure of 0.02 MPa to obtain the filtrate. The potassium concentration in this filtrate was determined to be 38 ppm by potentiometric titration with 0.01 N hydrochloric acid.

[0074] Example 2 (Synthesis test) A 1.17 mol / L aqueous magnesium sulfate solution and a No. 3 aqueous solution consisting of 0.46 mol / L Na2O and 1.44 mol / L SiO2 were continuously added in a constant amount to a continuous reaction vessel to induce a coprecipitation reaction. The reaction temperature was 40°C. The pH of the resulting reaction slurry was 8.9. The average particle size of the reactant particles was 8.2 μm. Furthermore, this reaction slurry was dehydrated by suction filtration using a Nutsche filter, and the resulting solid was washed with 0.05 mol / L sulfuric acid in an amount 15 times the weight of the solid to ion-exchange sodium in the solid, and then similarly washed with 20 times the amount of ion-exchanged water. The resulting solid was made into a slurry with a concentration of 250 g / L and spray-dried using a spray dryer.

[0075] The dried magnesium silicate compound of Example 2 obtained in this manner was subjected to various physical properties. As a result, the SiO2 / MgO molar ratio of the magnesium silicate compound of Example 2 was 3.9. The alkali metal content of the magnesium silicate compound of Example 2 was 0.17% by mass. The BET specific surface area of ​​the magnesium silicate compound of Example 2 was 259 m². 2 The concentration was / g. The total pore volume of the magnesium silicate compound in Example 2 was 0.56 cm³. 3 The concentration was / g. Furthermore, the pH of the magnesium silicate compound in Example 2 was 9.1. The solid acid content of the magnesium silicate compound in Example 2 was 0.90 mmol / g. The average particle size of the magnesium silicate compound in Example 2 was 43.8 μm. In addition, the powder X-ray diffraction pattern of the magnesium silicate compound in Example 2 showed that it was amorphous, as shown in Figure 1.

[0076] (Adsorption test 1) When the adsorption test was performed in exactly the same manner as in Adsorption Test 1 of Example 1, the potassium concentration in the filtrate was 211 ppm.

[0077] (Adsorption test 2) When the adsorption test was performed in exactly the same manner as in Adsorption Test 2 of Example 1, the potassium concentration in the filtrate was 104 ppm.

[0078] (Adsorption test 3) When the adsorption test was performed in exactly the same manner as in Adsorption Test 3 of Example 1, the potassium concentration in the filtrate was 34 ppm.

[0079] Example 3 (Synthesis test) A 1.17 mol / L aqueous magnesium sulfate solution and a No. 3 aqueous solution consisting of 0.46 mol / L Na2O and 1.44 mol / L SiO2 were continuously added in a constant amount to a continuous reaction vessel to induce a coprecipitation reaction. The reaction temperature was 40°C. The pH of the resulting reaction slurry was 8.9. The average particle size of the reactant particles was 8.2 μm. Furthermore, this reaction slurry was heated and stirred at 90°C for 2 hours. After that, the slurry was dewatered by suction filtration using a Nutsche filter, and the resulting solid was washed with 20 times the weight of the solid in ion-exchanged water. The resulting solid was made into a slurry with a concentration of 250 g / L and spray-dried using a spray dryer.

[0080] The dried magnesium silicate compound of Example 3 obtained in this manner was subjected to various physical properties. As a result, the SiO2 / MgO molar ratio of the magnesium silicate compound of Example 3 was 3.4. The alkali metal content of the magnesium silicate compound of Example 3 was 0.98% by mass. The BET specific surface area of ​​the magnesium silicate compound of Example 3 was 714 m². 2 The concentration was / g. The total pore volume of the magnesium silicate compound in Example 3 was 1.05 cm³. 3 The concentration was / g. Furthermore, the pH of the magnesium silicate compound in Example 3 was 9.6. The solid acid content of the magnesium silicate compound in Example 3 was 1.65 mmol / g. The average particle size of the magnesium silicate compound in Example 3 was 39.8 μm. In addition, the powder X-ray diffraction pattern of the magnesium silicate compound in Example 3 showed that it was amorphous.

[0081] (Adsorption test 1) When the adsorption test was performed in exactly the same manner as in Adsorption Test 1 of Example 1, the potassium concentration in the filtrate was 123 ppm.

[0082] (Adsorption test 2) When the adsorption test was performed in exactly the same manner as in Adsorption Test 2 of Example 1, the potassium concentration in the filtrate was 70 ppm.

[0083] (Adsorption test 3) When the adsorption test was performed in exactly the same manner as in Adsorption Test 3 of Example 1, the potassium concentration in the filtrate was 40 ppm.

[0084] Example 4 (Synthesis test) A 1.17 mol / L aqueous magnesium sulfate solution and a No. 3 aqueous solution consisting of 0.46 mol / L Na2O and 1.44 mol / L SiO2 were continuously added in a constant amount to a continuous reaction vessel to induce a coprecipitation reaction. The reaction temperature was 40°C. The pH of the resulting reaction slurry was 8.9. The average particle size of the reactant particles was 8.2 μm. Furthermore, this reaction slurry was heated and stirred at 90°C for 2 hours. After that, the slurry was dehydrated by suction filtration using a Nutsche filter, and the resulting solid was washed with 0.05 mol / L sulfuric acid in an amount 15 times the weight of the solid to ion-exchange sodium in the solid, and then similarly washed with 20 times the amount of ion-exchanged water. The resulting solid was made into a slurry with a concentration of 250 g / L and spray-dried using a spray dryer.

[0085] The dried magnesium silicate compound of Example 4 obtained in this manner was subjected to various physical properties measurements. The results showed that the SiO2 / MgO molar ratio of the magnesium silicate compound of Example 4 was 4.0. The alkali metal content of the magnesium silicate compound of Example 4 was 0.08% by mass. The BET specific surface area of ​​the magnesium silicate compound of Example 4 was 702 m². 2 The concentration was / g. The total pore volume of the magnesium silicate compound in Example 4 was 1.07 cm³. 3The concentration was / g. Furthermore, the pH of the magnesium silicate compound in Example 4 was 8.4. The solid acid content of the magnesium silicate compound in Example 4 was 1.62 mmol / g. The average particle size of the magnesium silicate compound in Example 4 was 39.8 μm. In addition, the powder X-ray diffraction pattern of the magnesium silicate compound in Example 4 showed that it was amorphous, as shown in Figure 2.

[0086] (Adsorption test 1) When the adsorption test was performed in exactly the same manner as in Adsorption Test 1 of Example 1, the potassium concentration in the filtrate was 162 ppm.

[0087] (Adsorption test 2) When the adsorption test was performed in exactly the same manner as in Adsorption Test 2 of Example 1, the potassium concentration in the filtrate was 78 ppm.

[0088] (Adsorption test 3) When the adsorption test was performed in exactly the same manner as in Adsorption Test 3 of Example 1, the potassium concentration in the filtrate was 33 ppm.

[0089] Comparative Example 1 (Synthesis test) A 1.35 mol / L aqueous magnesium sulfate solution and a No. 3 aqueous solution consisting of 0.55 mol / L Na2O and 1.73 mol / L SiO2 were continuously added in a constant amount to a continuous reaction vessel to induce a coprecipitation reaction. The reaction temperature was 40°C. The pH of the resulting reaction slurry was 9.3. The average particle size of the reactant particles was 12.8 μm. Furthermore, this reaction slurry was dewatered by suction filtration using a Nutsche filter, and the resulting solid was washed with 20 times the weight of the solid in ion-exchanged water. The resulting solid was made into a slurry with a concentration of 250 g / L and spray-dried using a spray dryer.

[0090] The dried magnesium silicate compound of Comparative Example 1 obtained in this manner was subjected to various physical properties. The results showed that the SiO2 / MgO molar ratio of the magnesium silicate compound of Comparative Example 1 was 3.6. The alkali metal content of the magnesium silicate compound of Comparative Example 1 was 1.60% by mass. The BET specific surface area of ​​the magnesium silicate compound of Comparative Example 1 was 126 m². 2 The concentration was / g. The total pore volume of the magnesium silicate compound in Comparative Example 1 was 0.24 cm³. 3 The concentration was / g. Furthermore, the pH of the magnesium silicate compound of Comparative Example 1 was 10.1. The solid acid content of the magnesium silicate compound of Comparative Example 1 was 0.61 mmol / g. The average particle size of the magnesium silicate compound of Comparative Example 1 was 40.6 μm. In addition, the powder X-ray diffraction pattern of the magnesium silicate compound of Comparative Example 1 showed that it was amorphous.

[0091] (Adsorption test 1) When the adsorption test was performed in exactly the same manner as in Adsorption Test 1 of Example 1, the potassium concentration in the filtrate was 424 ppm.

[0092] (Adsorption test 2) When the adsorption test was performed in exactly the same manner as in Adsorption Test 2 of Example 1, the potassium concentration in the filtrate was 283 ppm.

[0093] (Adsorption test 3) When the adsorption test was performed in exactly the same manner as in Adsorption Test 3 of Example 1, the potassium concentration in the filtrate was 65 ppm.

[0094] The measurement results of various physical properties of the magnesium silicate compounds in Examples 1-4 and Comparative Example 1 are shown in Table 1 below. Note that the potassium concentration in the filtrate during the adsorption test is denoted as "Remaining K amount" in Table 1.

[0095] [Table 1]

[0096] As shown in Table 1, the adsorbents made of magnesium silicate compounds in Examples 1 to 4 showed low residual potassium content in the adsorption test and demonstrated excellent adsorption performance for alkali metals. On the other hand, the adsorbent made of magnesium silicate compound in Comparative Example 1 showed high residual potassium content in the adsorption test and demonstrated insufficient adsorption performance for alkali metals. [Industrial applicability]

[0097] The adsorbent of the present invention has a significantly higher adsorption capacity than conventional adsorbents made of magnesium silicate compounds, and can adsorb substances with a small amount of use. Therefore, it can be suitably used as an adsorbent for various industrial applications. The adsorbent of the present invention is particularly useful as an adsorbent for adsorbing and removing alkali metal-containing basic catalysts when producing polyether polyols.

Claims

1. Amorphous magnesium silicate compound, The aforementioned magnesium silicate compound The alkali metal content is 1.20% by mass or less. The amount of solid acid is 0.90 mmol / g or more. BET specific surface area is 200 m ２ / g to 1000m ２ / g, A compound characterized by being represented by the following formula (1). (MgO) ｘ ・SiO ２ ・mH ２ O ・・・(1) [In equation (1), x is a number satisfying 0.1 ≤ x ≤ 0.5, and m is a number satisfying 0.1 ≤ m ≤ 1.5.]

2. The total pore volume of the magnesium silicate compound is 0.40 cm³. ３ / g ~ 1.50cm ３ The compound according to claim 1, wherein the amount is / g.

3. The compound according to claim 1, wherein the average particle size of the magnesium silicate compound is 2.0 μm to 60.0 μm.

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