Halogen adsorbent

Abstract

Provided is an adsorbent that exhibits a high removal rate for halogens even in hydrocarbon oil having high viscosity.　The adsorbent is a halogen adsorbent having the following configurations (1)-(4): (1) The adsorbent comprises an alkali metal in the range of 2-30% by mass in terms of M2O. (2) The adsorbent comprises Si and Al. (3) The adsorbent does not exhibit an X-ray diffraction pattern attributed to crystalline aluminosilicate. (4) The adsorbent has a pore volume, as measured by mercury porosimetry, of 0.65-1.50 mL / g on the basis of the weight of the adsorbent excluding the weight of the alkali metal.

Description

Halogen Adsorbent

[0001] The present invention relates to a halogen adsorbent.

[0002] In the chemical industry, halogens are sometimes recognized as harmful elements. For example, in the fields of petroleum refining and petrochemistry, if halogen is contained in hydrocarbon oil that serves as a raw material for various products, it causes corrosion of equipment and catalyst poisoning, and therefore its removal is desired. Furthermore, in recent years, attention has been focused on the field of chemical recycling for obtaining hydrocarbon oil from waste plastics, and demand for removing chlorine derived from chlorine-based polymers such as polyvinyl chloride contained in waste plastics has been increasing. As one method for removing these halogen elements, a method using an adsorbent is known.

[0003] As an adsorbent for removing halogens, an adsorbent obtained by mixing an alkali metal salt having strong basicity with an alumina compound is known. For example, Patent Document 1 discloses a method for producing an adsorbent by mixing an alumina compound and a solid metal carbonate and calcining the mixture. It is also disclosed that sesquicarbonate (sodium sesquicarbonate) is a preferred form as the solid metal carbonate.

[0004] Patent Document 2 discloses a method for producing an adsorbent, which comprises mixing at least one alumina compound together with water with a solid metal carbonate to form a mixture, then heating the mixture to a temperature of up to 100°C, and heating for a time sufficient for the solid metal carbonate and the alumina to react to form an aluminum-containing hydroxycarbonate. It is also disclosed that an alkali metal carbonate is a preferred form as the metal carbonate.

[0005] Patent Document 3 also discloses an adsorbent for organic halogen compound gas, which is a substance obtained by causing a crystalline aluminosilicate to contain an alkali metal or an alkaline earth metal, wherein the metal content accounts for 0.1 to 50% by weight.

[0006] However, these adsorbents have a problem that the removal rate tends to be low when removing halogen from high-viscosity hydrocarbon oil.

[0007] Special Publication No. 2009-515697 Special Publication No. 2008-540083 Publication of Japanese Patent Application Laid-open No. 2009-56242

[0008] To provide an adsorbent that removes halogens quickly, even in highly viscous hydrocarbon oils.

[0009] The inventors focused on the pore distribution of the adsorbent and found an adsorbent that removes halogens quickly even in highly viscous hydrocarbon oils. Specifically, they found a halogen adsorbent having the following configurations (1) to (4): (1) Contains alkali metals in an amount of 2% or more by mass and 30% or less by mass on an M2O basis. (2) Contains Si and Al. (3) Does not exhibit an X-ray diffraction pattern attributed to crystalline aluminosilicate. (4) The pore volume measured by the mercury intrusion method is in the range of 0.65 mL / g or more and 1.50 mL / g or less on a weight basis of the adsorbent excluding the weight of the alkali metals.

[0010] According to the present invention, an adsorbent that removes halogens quickly, even in highly viscous hydrocarbon oils, can be provided.

[0011] This invention includes an invention relating to a halogen adsorbent (hereinafter also referred to as "the adsorbent of the present invention"). The adsorbent of the present invention will be described in detail below.

[0012] In the adsorbent of the present invention, alkali metals act as adsorbents for adsorbing halogens. Si (silicon) and Al (aluminum) are components contained in the carrier and exist in the adsorbent in the form of oxides or hydroxides. However, as described in Patent Document 3, they do not exist in the form of crystalline aluminosilicate. By increasing the pore volume of the adsorbent containing these, the halogen removal rate can be increased even in highly viscous hydrocarbon oils.

[0013] The adsorbent of the present invention contains alkali metals in an amount of 2% by mass or more and 30% by mass or less, calculated as M2O. In M2O, M represents alkali metals. Among the alkali metals, it is preferable to contain at least one of sodium and potassium. Increasing the alkali metal content increases the amount of halogen adsorbed. Conversely, decreasing the alkali metal content also relatively increases the content of Si and Al, which tends to increase the pore volume. Therefore, the alkali metal content is preferably in the range of 3% by mass or more and 25% by mass or less, and more preferably in the range of 4% by mass or more and 20% by mass or less.

[0014] The adsorbent of the present invention contains Si and Al. Si acts as a carrier for supporting alkali metals and also acts as a pore-forming agent that imparts specific pores to the carrier. Increasing the Si content tends to increase the pore volume. Therefore, the Si content is preferably 3% by mass or more, more preferably 10% by mass or more, and particularly preferably 20% by mass or more, in terms of SiO2. The upper limit of the Si content is preferably 50% by mass or less, more preferably 45% by mass or less, and particularly preferably 40% by mass or less. Lowering the Si content allows for a relative increase in the Al content. Al is an element that reacts with both acids and bases and acts as a carrier for dispersing alkali metals and also as an adsorbent for halogens. Therefore, the Al content is preferably 35% by mass or more, more preferably 40% by mass or more, and particularly preferably 45% by mass or more, in terms of Al2O3. The upper limit of the Al content is preferably 75% by mass or less, more preferably 70% by mass or less, and particularly preferably 65% ​​by mass or less. Furthermore, the ratio of Si to Al is preferably in the range of 0.01 or more and 1 or less in terms of SiO2 / Al2O3 weight ratio, more preferably in the range of 0.1 or more and 0.8 or less, and particularly preferably in the range of 0.2 or more and 0.6 or less. Such an adsorbent allows for a faster halogen removal rate.

[0015] The adsorbent of the present invention does not exhibit an X-ray diffraction pattern attributed to crystalline aluminosilicate. Crystalline aluminosilicate is a mineral called zeolite, as shown in Patent Document 3. Zeolites are classified according to their crystal structure, and each exhibits an X-ray diffraction pattern corresponding to its respective crystal structure. In contrast, the adsorbent of the present invention does not exhibit an X-ray diffraction pattern attributed to crystalline aluminosilicate. Therefore, it is considered that the aforementioned Si and Al exist in the adsorbent in the form of oxides or hydroxides.

[0016] The adsorbent of the present invention has a pore volume measured by the mercury intrusion method that is in the range of 0.65 mL / g or more and 1.50 mL / g or less, based on the weight of the adsorbent excluding the weight of the alkali metal. In the present invention, as the amount of alkali metal contained in the adsorbent increases, the amounts of Si and Al decrease relatively, so the apparent pore volume tends to decrease. Therefore, by using the weight of the adsorbent excluding the weight of the alkali metal as the basis, this parameter expresses that the pore volume of the adsorbent of the present invention is large regardless of the amount of alkali metal. When this pore volume is large, highly viscous hydrocarbon oil diffuses more easily into the adsorbent, so the halogen removal rate tends to increase. Also, when this pore volume is small, the crush strength of the adsorbent tends to increase. Therefore, this pore volume is preferably in the range of 0.70 mL / g or more and 1.40 mL / g or less, and more preferably in the range of 0.70 mL / g or more and 1.20 mL / g or less. Furthermore, the proportion of pores larger than 12 nm in the total pore volume is preferably 30% or more, more preferably 40% or more, and particularly preferably 50% or more. Increasing the number of pores with larger diameters tends to increase the halogen removal rate.

[0017] The specific surface area of ​​the adsorbent of the present invention is 100 m². 2 It is preferable that it be 120m or more per gram. 2 It is more preferable that the amount is 130m or more per gram. 2It is particularly preferable that the amount is greater than or equal to / g. Since halogen adsorption occurs on the surface, the amount of halogen adsorbed tends to increase as the specific surface area increases. Therefore, there is no particular upper limit to the specific surface area. 250m 2 It may be less than or equal to / g, and 225m 2 It may be less than / g, and 200m 2 It may be less than or equal to / g. In this invention, the specific surface area refers to the specific surface area determined by the BET1 point method.

[0018] In the adsorbent of the present invention, the amount of 2-hexyldecanoic acid adsorbed is preferably 0.20 g to 0.50 g per 1 g of adsorbent, more preferably 0.23 g to 0.45 g, and particularly preferably 0.25 g to 0.40 g. When the adsorption amount is within this range, the removal rate of organic halogens tends to be faster. Furthermore, when the medium is an organic compound, the progress of side reactions caused by solid bases can also be suppressed. In the present invention, the amount of 2-hexyldecanoic acid adsorbed is an indicator of the amount of solid base present in pores of about 2 nm or larger. Since 2-hexyldecanoic acid is acidic and has a certain molecular size, it does not adsorb to solid bases present in pores smaller than this molecule. For example, since the pore diameter of molecular sieves is smaller than that of 2-hexyldecanoic acid, the adsorption amount will be small.

[0019] The adsorbent of the present invention is preferably spherical, columnar (including cylindrical and tetrahedron shapes), or similar shapes. Forming it into such shapes makes it easier to impart macropores. Furthermore, its size (minimum length of the outer diameter of the adsorbent) is preferably in the range of 0.5 mm or more and 6 mm or less. If the adsorbent is small, the contact area between the adsorbent and the hydrocarbon oil increases, so the adsorption rate of halogens contained in the hydrocarbon increases. If the hydrocarbon oil is highly viscous, it is preferable to increase the size of the adsorbent or to make it three-lobed or four-lobed in order to reduce the differential pressure.

[0020] The crushing strength of the adsorbent of the present invention is preferably 3 N / mm or more, more preferably 4 N / mm or more, and particularly preferably 5 N / mm or more. A higher crushing strength makes it less likely to collapse when filling a reactor or the like with the adsorbent. Despite having a large pore volume (many gaps), the adsorbent of the present invention has a crushing strength of a certain level or higher. This crushing strength may be 20 N / mm or less, 15 N / mm or less, or 10 N / mm or less.

[0021] The adsorbent of the present invention can be used to remove halogens contained in high-viscosity hydrocarbon oils. However, it is not limited to such hydrocarbon oils and can also be used as an adsorbent to remove halogens generated in various processes. The adsorbent of the present invention can be suitably used as an adsorbent for removing organic halogens, and more suitably used as an adsorbent for removing organochlorine compounds. Furthermore, it can be suitably used as an adsorbent for removing halogens contained in high-viscosity media having a viscosity of 2 mPa·s or more at 25°C.

[0022] The adsorbent of the present invention can be prepared, for example, by a manufacturing method comprising the following steps (1) to (7): (1) Slurry preparation step of preparing a slurry containing Si and Al; (2) Washing step of washing away solids contained in the slurry; (3) Kneading step of kneading the solids to prepare molding clay; (4) Molding step of extruding the molding clay to prepare pellets; (5) Carrier preparation step of firing the pellets to prepare a carrier containing Si and Al; (6) Impregnation step of impregnating the carrier with an alkali metal aqueous solution to prepare the adsorbent.

[0023] The following describes in detail the method for producing the adsorbent of the present invention as an example, but the method for producing the adsorbent of the present invention is not limited to this method. For example, the adsorbent of the present invention can also be prepared by preparing a slurry containing Al, mixing the solid content in this slurry with silica particles to prepare a molding clay, and then performing the steps from (4) onward (for example, Example 3).

[0024] In the slurry preparation step, a slurry containing Si and Al is prepared. In this step, a slurry containing Si and Al is obtained by mixing a basic aqueous solution containing Si with an acidic aqueous solution containing Al and adjusting the pH to a range of 7 or higher and 9.5 or lower. Alternatively, a slurry containing Si and Al can also be obtained by mixing silica sol and alumina sol and adjusting the pH to a range of 7 or higher and 9.5 or lower.

[0025] In this process, a basic aqueous solution containing Si can be prepared by adding water to sodium silicate. Basic aluminum compounds can also be added at this time. For example, sodium aluminate or an aqueous solution of sodium aluminate can be added.

[0026] In this process, water can be added to aluminum sulfate to prepare an acidic aqueous solution containing Al. Alternatively, aluminum can be dissolved in sulfuric acid to prepare an acidic aqueous solution containing Al.

[0027] The temperature at which the basic aqueous solution containing Si and the acidic aqueous solution containing Al are mixed is preferably in the range of 40°C to 80°C, and more preferably in the range of 50°C to 70°C. When mixed at such temperatures, Si-containing particles and Al-containing particles grow in the slurry containing Si and Al, and the difference in their growth rates makes it easier for more pores to be formed. Furthermore, it is more preferable to hold the mixture at this temperature for 20 minutes or more to allow it to mature after mixing.

[0028] In the washing step, the solid components contained in the slurry are washed to remove components other than Si and Al. Examples of components other than Si and Al include alkali metal salts and sulfates. This step can be performed by methods such as removing and washing the solid components from the slurry, or by repeatedly replacing the solvent in the slurry. Water, aqueous ammonia, or aqueous ammonium sulfate solution can be used as the solvent for washing. Methods such as flow washing, where these solvents are circulated over the solid components, or suspension washing, where the solid components are suspended in these solvents and then the solvents are removed, can be used. Furthermore, after dispersing the washed solid components in water to form a slurry, this slurry can be aged at a temperature between 80°C and 99°C.

[0029] In the kneading process, the solid components are mixed to prepare molding clay. In this process, molding clay can be prepared by kneading the cake-like solid components obtained in the previous process using a kneader or the like. Alternatively, molding clay can also be prepared by kneading a slurry containing solid components while heating it.

[0030] In the molding process, the molding clay is extruded to prepare pellets. In this process, the pellets can be prepared by extruding the molding clay using an extrusion molding machine. If the surface of the pellets is wet, the pellets will stick together, so they can be dried using conventionally known methods to remove the solvent that causes wetting. For example, the pellets can be dried at a temperature of 120°C or lower using a heating furnace.

[0031] In the carrier preparation step, the pellets are calcined to prepare a carrier containing Si and Al. In this step, the pore structure of the pellets is changed by calcining them in a heating furnace. This change in pore structure is thought to occur due to dehydration reactions of components derived from the solid content containing Si and Al, and the removal of volatile components. From the viewpoint of promoting the dehydration reaction, the calcination temperature is preferably in the range of 300°C or higher and 700°C or lower, more preferably in the range of 350°C or higher and 650°C or lower, and particularly preferably in the range of 400°C or higher and 600°C or lower. The calcination time varies depending on the amount of pellets prepared, so the range cannot be uniquely determined. As a guideline, calcination should be performed for a range of 1 hour or more and 48 hours or less. The atmosphere in this step may be an air atmosphere or an inert gas atmosphere.

[0032] In the impregnation step, an alkali metal aqueous solution is impregnated into the carrier to prepare the adsorbent. Conventional impregnation methods such as equilibrium adsorption, pore filling, evaporation to dryness, and spray loading can be used in this step. In this manufacturing method, spray loading is preferred because it allows for more precise control of the alkali metal loading amount. If the surface of the adsorbent is wet, it can be dried using conventional methods. For example, the adsorbent can be dried at a temperature of 120°C or lower using a heating furnace.

[0033] In this process, an alkali metal aqueous solution can be prepared by dissolving an alkali metal salt in water. For example, alkali metal hydroxides, alkali metal carbonates, alkali metal nitrates, alkali metal sulfates, alkali metal acetates, etc., can be used as alkali metal salts. Multiple of these can also be used in combination. In this process, it is preferable to use at least one of alkali metal hydroxides and alkali metal carbonates.

[0034] This manufacturing method may include a step of calcining the adsorbent described above. In this step, water is further removed from the adsorbent. From the viewpoint of promoting water removal, the calcination temperature is preferably in the range of 150°C or higher and 450°C or lower, more preferably in the range of 200°C or higher and 400°C or lower, and particularly preferably in the range of 250°C or higher and 350°C or lower. The calcination time varies depending on the amount of adsorbent prepared, so the range cannot be uniquely determined. As a guideline, calcination should be performed for a range of 1 hour or more and 48 hours or less. The atmosphere in this step may be an air atmosphere, an inert gas atmosphere, or a reduced pressure atmosphere.

[0035] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0036] (Measurement and Evaluation Methods) In this embodiment, various measurements and evaluations were performed using the following methods.

[0037] [1] A carrier with a water absorption capacity of approximately 20 g was immersed in 100 mL of pure water for 1 hour. After that, the carrier was removed, the surface was wiped dry, and the weight of the carrier after immersion was measured. Using this value, the amount of water absorbed by the carrier was calculated from equation (1) below. The weight of pure water per unit volume was assumed to be 1 g / mL.

[0038] Water absorption of the carrier [mL / g] = (Weight of carrier after immersion - Weight of carrier before immersion) / Weight of carrier before immersion ... (1)

[0039] [2] Pore volume measurement using mercury intrusion method Approximately 3 g of the adsorbent obtained in each example was placed in a porcelain crucible and heated at 110°C for 2 hours. The adsorbent was then placed in a desiccator and cooled to room temperature to obtain a sample for measurement. The pore distribution of this sample was measured using the mercury intrusion method (measurement device: Microtrac-Bell Co., Ltd., BELPORE HP, mercury contact angle: 130°, surface tension: 473 N / m, device measurement range: 0.1 MPa to 222.5 MPa). From the obtained pore distribution, the total volume of pores with a diameter of 5 nm or more was calculated and this was taken as the pore volume of the adsorbent. In addition, the pore volume based on the weight of the adsorbent, excluding the weight of alkali metals, was also calculated using this pore volume. Furthermore, the pore volume based on the weight of the adsorbent, excluding the weight of alkali metals, for pores of 12 nm or more was also calculated. The percentage of pore volume with a diameter of 12 nm or larger refers to the ratio (%) of the pore volume with a diameter of 12 nm or larger to the total pore volume based on the weight of the adsorbent, excluding the weight of alkali metals.

[0040] [3] Composition Analysis The adsorbent was ground into a powder using a mortar and pestle. 3 g of this powder was dissolved in the mortar and diluted with pure water to a volume of 500 mL. Using this as the measurement sample, the Si concentration, Al concentration, Na concentration, and K concentration were measured using an inductive plasma (ICP) emission spectrometer (Shimadzu Corporation, ICPS-8100, analysis software ICPS-8000). These values ​​were used to convert to the Si content, Al content, Na content, and K content per gram of adsorbent. Note that each content was converted to the value of SiO2, Al2O3, Na2O, and K2O, respectively.

[0041] [4] X-ray diffraction measurement X-ray diffraction measurement was performed using an X-ray diffractometer manufactured by Rigaku Corporation (MultiFlex, manufactured by Rigaku Corporation). First, the adsorbent was ground in a mortar, packed into a sample plate, and X-ray diffraction (radiation source: Cu-Kα ray) measurement was performed under the conditions of a tube voltage of 40 kV, a tube current of 20 mA, a scanning range of 10 to 70°, a divergence slit of 1.0 mm, a scattering slit of 1.0 mm, a light-receiving slit of 0.3 mm, and a scanning speed of 4° / min. When no peak derived from the crystal structure of zeolite was found in the obtained X-ray diffraction pattern, it was determined that no crystalline aluminosilicate was contained.

[0042] [5] Specific surface area The adsorbent obtained in each example was collected in a porcelain crucible, heat-treated at 110°C for 2 hours, then placed in a desiccator and cooled to room temperature. Next, 0.3 g of the measurement sample was collected, and the specific surface area (m 2 / g) was measured by the BET one-point method using a fully automatic surface area measuring apparatus (Macsorb HM model-1220 manufactured by Mountech Co., Ltd.).

[0043] [6] Halogen adsorption test in low-viscosity hydrocarbons The adsorbent obtained in each example was packed into a reaction tube such that the layer height was 20 mm. This reaction tube was attached to an adsorption test apparatus. Nitrogen was passed through this reaction tube, and pretreatment was performed at 150°C for 1 hour. Thereafter, the reaction tube was cooled to 40°C and this temperature was maintained. n-hexane containing 261 ppm of t-butyl chloride (100 ppm as Cl) was passed through the reaction tube at a rate of 1 mL / min. After the flowing liquid reached the outlet of the reaction tube, the flow was continued for 1 hour, and the entire amount of the liquid after flowing was stored. The concentration of chlorine contained in the liquid after flowing was measured using a trace chlorine analyzer (TCL-2100V, manufactured by Nitto Seiko Analytech Co., Ltd.). Using this chlorine concentration, the halogen removal rate was calculated from the following formula (2). In the present specification, the removal rate after 1 hour of liquid passage was used as a surrogate value for the rate index.

[0044] Halogen removal rate [%] = 100-(chlorine concentration after flow [ppm] / 100 [ppm])×100 --- (2)

[0045] [7] Halogen adsorption test in high-viscosity hydrocarbons A halogen adsorption test was performed in the same manner as in [6] above, except that n-hexane containing 261 ppm of t-butyl chloride (100 ppm as Cl) was replaced with n-hexadecane (higher viscosity than n-hexane) containing 261 ppm of t-butyl chloride (100 ppm as Cl), and the halogen removal rate was calculated. In this specification, the removal rate after 1 hour of liquid flow was used as a surrogate value for the rate index.

[0046] [8] Test for solid basicity by organic acid adsorption test Using a 100 mL volumetric flask, 10.00 g of 2-hexyldecanoic acid was dissolved in toluene to prepare a 2-hexyldecanoic acid / toluene solution. 1.00 g of adsorbent was weighed into a 30 mL screw vial, 1.0 mL of toluene was added, and then 5 mL of the 2-hexyldecanoic acid / toluene solution was added. The lid of the screw vial was closed and it was kept in a 50°C constant temperature bath for 5 hours, after which the adsorbent was filtered off. The obtained adsorbent was transferred to a new 30 mL screw vial, 10 mL of toluene was added and the lid was closed, and it was kept at 50°C for 1 hour, after which it was filtered off again. Furthermore, another 10 mL of new toluene was added, the lid was closed in the same manner and it was kept at 50°C for 24 hours, after which the adsorbent was filtered off. The obtained adsorbent was dried in a vacuum desiccator for 6 hours, and the weight after drying was measured. The amount of adsorbed 2-hexyldecanoic acid was calculated by subtracting 1.00 g of the adsorbent from this measured weight.

[0047] [9] Length, Diameter, and Crushing Strength Measurement: Representative samples were obtained from the adsorbent using a reduction chamber. The lengths of 20 pellets from the representative samples were measured using a digital caliper. The average value of these measurements was taken as the length of the adsorbent. The diameter of the pellets was also measured using a digital caliper. The average value of these measurements was taken as the diameter of the adsorbent. Furthermore, the crushing strength of the 20 pellets whose lengths were measured was measured using a Kiya hardness tester. The strength per unit length of the pellet (N / mm) was calculated by dividing the average value of the crushing strength of the 20 pellets by the average value of the lengths of the 20 pellets.

[0048] (Raw materials used in the examples) Sodium silicate aqueous solution: 2.5% by mass in terms of SiO2 concentration Sodium aluminate aqueous solution: 22% by mass in terms of Al2O3 concentration Sodium gluconate aqueous solution: 25% by mass concentration Aluminum sulfate aqueous solution: 2.5% by mass in terms of Al2O3 concentration Silica powder: Toxil 928 (manufactured by Oriental Silicas Corporation, average particle size 11.8 μm) Potassium hydroxide: 83.9% by mass in terms of K2O concentration Potassium carbonate: 68.2% by mass in terms of K2O concentration Sodium hydroxide: 77.5% by mass in terms of Na2O concentration Sodium carbonate: 58.5% by mass in terms of Na2O concentration

[0049] [Example 1] <Slurry Preparation Process> A sodium aluminate aqueous solution, a sodium gluconate aqueous solution, and deionized water were mixed to prepare a mixture (5% by mass in terms of Al2O3 concentration) weighing 23.1 kg. Next, 3.1 kg of deionized water was filled into a tank with a steam jacket. The aforementioned mixture weighing 23.1 kg and a sodium silicate aqueous solution weighing 15.0 kg were added to this tank and mixed to prepare a basic aqueous solution containing Si and Al. Then, this basic aqueous solution was heated to 60°C while stirring. To this basic aqueous solution, 38.9 kg of aluminum sulfate aqueous solution (acidic aqueous solution containing Al) was added at a constant rate over 10 minutes. Then, the mixture was held for 30 minutes while stirring to obtain a slurry containing Si and Al. At this time, the pH of the slurry was 9.2.

[0050] <Washing Process> The slurry obtained in the previous process was filtered to obtain a cake-like solid. 25 L of ammonia water (concentration 0.3 mass%) was passed through this solid to wash it. This solid was mixed with deionized water to create a new slurry with an Al2O3 equivalent concentration of 10 mass%. Ammonia water was added to this slurry to adjust the pH to 10.5. Then, the slurry was heated to 95°C while being stirred and maintained for 10 hours to mature.

[0051] <Kneading Process> The slurry obtained in the above process was filled into a dual-arm kneader and kneaded while heating to obtain molding clay.

[0052] <Molding Process> The molding clay obtained in the above process was molded into cylindrical pellets with a diameter of 1.8 mm using a screw-type extrusion molding machine. These pellets were then dried at 110°C for 12 hours. After drying, the pellets were cut to a length of 3 mm.

[0053] <Carrier Preparation Process> The pellets obtained in the above process were calcined at 500°C for 3 hours to obtain a carrier.

[0054] <Impregnation Process> The amount of water absorbed by the carrier obtained in the above process was measured by the method in [1] above. Next, an impregnation solution was prepared by dissolving 200 g of potassium hydroxide in ion-exchanged water equivalent to the amount of water absorbed by 800 g of this carrier. After spraying the impregnation solution onto 800 g of this carrier, it was dried at 120°C to obtain an adsorbent.

[0055] <Casturing Process> The adsorbent obtained in the above process was calcined at 300°C for 3 hours to obtain an adsorbent. The obtained adsorbent was subjected to the measurements or evaluations described in [2] to [9] above. The results are shown in Table 1.

[0056] [Example 2] <Slurry Preparation Process> A sodium aluminate aqueous solution, a sodium gluconate aqueous solution, and deionized water were mixed to prepare a mixture (5% by mass in terms of Al2O3 concentration) weighing 32.0 kg. Next, 11.0 kg of deionized water was filled into a tank with a steam jacket. 32.0 kg of the aforementioned mixture and 15.0 kg of sodium silicate aqueous solution were added to this tank and mixed to prepare a basic aqueous solution containing Si and Al. This basic aqueous solution was then heated to 60°C while being stirred. 38.9 kg of aluminum sulfate aqueous solution (acidic aqueous solution containing Al) was added to this basic aqueous solution at a constant rate over 10 minutes. The mixture was then held for 30 minutes while stirring to obtain a slurry containing Si and Al. At this time, the pH of the slurry was 9.2.

[0057] <Washing Process to Carrier Preparation Process> A carrier was obtained in the same manner as in Example 1, except that the slurry obtained in the above process was used.

[0058] <Impregnation Process to Firing Process> The amount of water absorbed by the carrier obtained in the above process was measured by the method in [1] above. Next, an impregnation solution was prepared by dissolving 100 g of sodium carbonate in ion-exchanged water equivalent to the amount of water absorbed by 900 g of this carrier. After spraying the impregnation solution onto 900 g of this carrier, it was dried at 120°C to obtain an adsorbent. The adsorbent was obtained in the same manner as in Example 1 in the subsequent steps. The obtained adsorbent was measured or evaluated according to [2] to [9] above. The results are shown in Table 1.

[0059] [Example 3] <Steps for preparing an Al-containing slurry> A sodium aluminate aqueous solution, a sodium gluconate aqueous solution, and deionized water were mixed to prepare a mixture (5% by mass in terms of Al2O3 concentration) of 35.1 kg. Next, 13.2 kg of deionized water was filled into a tank with a steam jacket. 35.1 kg of the aforementioned mixture was added to this tank and mixed to prepare an Al-containing basic aqueous solution. Then, this basic aqueous solution was heated to 60°C while stirring. 29.9 kg of aluminum sulfate aqueous solution (an acidic aqueous solution containing Al) was added to this basic aqueous solution at a constant rate over 10 minutes. Then, the mixture was held for 30 minutes while stirring to obtain an Al-containing slurry. At this time, the pH of the slurry was 9.4.

[0060] <Washing Process> A slurry was obtained in the same manner as in Example 1, except that the slurry obtained in the above process was used.

[0061] <Kneading Process to Carrier Preparation Process> A carrier was obtained in the same manner as in Example 1, except that the entire amount of slurry obtained in the above process and 1.2 kg of silica powder were loaded into a double-arm kneader.

[0062] <Impregnation Process to Firing Process> The amount of water absorbed by the carrier obtained in the above process was measured by the method in [1] above. Next, an impregnation solution was prepared by dissolving 200 g of potassium carbonate in ion-exchanged water equivalent to the amount of water absorbed by 800 g of this carrier. After spraying the impregnation solution onto 800 g of this carrier, it was dried at 120°C to obtain an adsorbent. The adsorbent was obtained in the same manner as in Example 1 in the subsequent steps. The obtained adsorbent was measured or evaluated according to the methods in [2] to [9] above. The results are shown in Table 1.

[0063] [Example 4] An adsorbent was obtained in the same manner as in Example 3, except that the calcination process was not performed. The obtained adsorbent was subjected to the measurements or evaluations described in [2] to [9] above. The results are shown in Table 1.

[0064] [Example 5] An adsorbent was obtained in the same manner as in Example 2, except that 200 g of sodium carbonate was used in the impregnation process. The obtained adsorbent was subjected to the measurements or evaluations described in [2] to [9] above. The results are shown in Table 1.

[0065] [Comparative Example 1] An adsorbent was obtained in the same manner as in Example 3, except that silica powder was not added in the kneading process. The obtained adsorbent was subjected to the measurements or evaluations described in [2] to [9] above. The results are shown in Table 1.

[0066] [Comparative Example 2] An adsorbent was obtained in the same manner as in Comparative Example 1, except that 200 g of potassium carbonate was replaced with 100 g of sodium hydroxide in the impregnation process. The obtained adsorbent was subjected to the measurements or evaluations described in [2] to [9] above. The results are shown in Table 1.

[0067] [Comparative Example 3] Pellets were obtained in the same manner as in Example 3, except that 625 g of sodium carbonate was added to the slurry obtained in the washing step. These pellets were calcined at 500°C for 3 hours to obtain an adsorbent. The obtained adsorbent was subjected to the measurements or evaluations described in [2] to [9] above. The results are shown in Table 1.

[0068] [Comparative Example 4] Pellets were obtained in the same manner as in Example 3, except that 625 g of sodium carbonate was added during the kneading process. These pellets were calcined at 500°C for 3 hours to obtain an adsorbent. The obtained adsorbent was subjected to the measurements or evaluations described in [2] to [9] above. The results are shown in Table 1.

[0069] [Comparative Example 5] Molecular sieves 13X 1 / 16 manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. were used as the adsorbent in Comparative Example 5. The measurements or evaluations described in [2] to [9] above were performed on this adsorbent. The results are shown in Table 1.

[0070]

Claims

1. A halogen adsorbent having the following configurations (1) to (4): (1) Contains alkali metals in an amount of 2% by mass or more and 30% by mass or less on an M2O basis. (2) Contains Si and Al. (3) Does not exhibit an X-ray diffraction pattern attributed to crystalline aluminosilicate. (4) The pore volume measured by the mercury intrusion method is in the range of 0.65 mL / g or more and 1.50 mL / g or less on a weight basis of the adsorbent excluding the weight of the alkali metals.

2. The halogen adsorbent according to claim 1, wherein the proportion of pore volume of 12 nm or larger to the total pore volume is 30% or more.

3. The halogen adsorbent according to claim 1, wherein the ratio of Si to Al is 0.01 or more and 1 or less in terms of SiO2 / Al2O3 weight ratio.

4. Specific surface area of ​​100 m² 2 / g or more, 250m 2 The halogen adsorbent according to claim 1, wherein the amount is less than or equal to / g.

5. The halogen adsorbent according to any one of claims 1 to 4, wherein the amount of 2-hexyldecanoic acid adsorbed is 0.20 g or more and 0.50 g or less per 1 g of adsorbent.

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