Method for producing alkaline earth metal ion-exchanged zeolite molded body

Abstract

To provide a method for producing an alkaline earth metal-containing zeolite by which an alkaline earth metal can be ion-exchanged uniformly with a packed zeolite at a high ion exchange rate when the alkaline earth metal is allowed to be contained in the zeolite by using a large facility.SOLUTION: A method for producing an alkaline earth metal ion-exchanged zeolite molded article comprises at least the steps (1) to (3) below when an alkaline earth metal aqueous solution is brought into contact with a zeolite molded article to produce the alkaline earth metal ion-exchanged zeolite molded article. Step (1): a packing device is packed with a zeolite molded article up to a length L (m) in a supply direction of the alkaline earth metal aqueous solution. Step (2): after the step (1), the alkaline earth metal aqueous solution is supplied into the packing device, in which a contact time T (hr) is set to T≥L×2.5. Step (3): after the step (2), cleaning is carried out in an aqueous medium until the pH of a cleaning effluent reaches 5.5 to 9.5.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing alkaline earth metal ion-exchanged zeolite shaped bodies, and in particular to a method for producing alkaline earth metal ion-exchanged zeolite shaped bodies that can achieve a uniform and high alkaline earth metal ion exchange rate for the filled zeolite shaped bodies and that is particularly suitable for circulating ion exchange using large-scale facilities. [Background technology]

[0002] Medium-pore zeolites have micropores with an entrance diameter of approximately 0.5 nm, which act as an effective reaction field for molecules with molecular diameters close to the pore diameter. Therefore, they are useful as highly selective catalysts in hydrocarbon conversion reactions. Examples of the use of MFI-type zeolites, which are representative medium-pore zeolites, as catalysts include the disproportionation of toluene (see, for example, Patent Document 1), the isomerization of xylene (see, for example, Patent Document 2), and the aromatization of aliphatic hydrocarbons (see, for example, Patent Document 3).

[0003] In order to satisfy the above-mentioned catalytic activity, a method has been proposed in which alkaline earth metals are introduced into a proton-type MFI zeolite catalyst to adjust the acidity of the zeolite and obtain catalytic activity. Methods for incorporating alkaline earth metals into zeolite include impregnation of powdered zeolite, evaporation to dryness, direct mixing, and ion exchange. Specific examples include a method for producing a xylene isomerization catalyst by impregnating ZSM-5 powder with calcium (see, for example, Patent Document 4), and a method for producing a catalyst for a catalytic pyrolysis process for producing light olefins by immersing ZSM-5 in an aqueous solution containing phosphorus and calcium compounds and drying the resulting mixture (see, for example, Patent Document 5).

[0004] In addition, methods proposed for incorporating alkaline earth metals into shaped and processed zeolites include, for example, a method of impregnating ZSM-5 extrudates with alkaline earth metal salts or alkaline earth metal salt solutions molten at high temperatures to support the metals (see, for example, Patent Document 6), and a method of producing a halogen transfer catalyst for diiodobenzene by neutralizing proton-type ZSM-5 with a saturated aqueous calcium hydroxide solution and then washing with deionized water (see, for example, Patent Document 7). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 11-255677 [Patent Document 2] Japanese Patent Application Publication No. 2-255628 [Patent Document 3] Japanese Patent Application Publication No. 10-33987 [Patent Document 4] Special publication 2010-510047 [Patent Document 5] Japanese Patent Application Publication No. 11-192431 [Patent Document 6] Japanese Patent Application Publication No. 55-102440 [Patent Document 7] Japanese Patent Application Publication No. 63-44537 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the methods proposed in Patent Documents 4 and 5 involve bringing calcium into contact with powdered zeolite, and no consideration has been given to uniform ion exchange and inclusion in a zeolite molded body. Therefore, when using the zeolite as a molded body industrially, additional steps and processes are required to mold the zeolite after incorporating alkaline earth metals, which makes the process complicated.

[0007] Furthermore, in the method of introducing alkaline earth metals into zeolite molded bodies proposed in Patent Document 6, the impregnation method does not involve a washing step, so the alkaline earth metal is supported on sites other than the ion exchange sites, raising concerns about a decrease in performance. In addition, the amount of metal salt and the number of exchanges in the ion exchange method have not been considered, and complex operations such as multiple treatments are required to achieve a high amount of alkaline earth metal.

[0008] The method proposed in Patent Document 7 does not consider the ion exchange rate, nor does it propose any manufacturing method using large-scale equipment, which is required for industrial applications, or the stability of quality during such manufacturing. When ion-exchanging zeolite shaped bodies using large-scale equipment, ion exchange proceeds preferentially at the inlet where the alkaline earth metal solution is supplied, resulting in a low concentration of the alkaline earth metal solution in other areas. This concentration gradient can easily lead to unevenness in the ion-exchange rate.

[0009] Therefore, in producing alkaline earth metal ion-exchanged zeolite shaped bodies, there is a demand for a production method that combines a high alkaline earth metal ion exchange rate with uniform quality in ion exchange using large-scale equipment suitable for industrial production. [Means for solving the problem]

[0010] Therefore, the present inventors conducted extensive research to solve the above problems and found that a production method that satisfies both a high alkaline earth metal ion exchange rate and uniformity can be achieved by treating the zeolite shaped body with an alkaline earth metal aqueous solution under specific conditions when the alkaline earth metal aqueous solution is brought into contact with the zeolite shaped body, thereby completing the present invention.

[0011] That is, the present invention relates to a method for producing an alkaline earth metal ion-exchanged zeolite shaped body, which is characterized by going through at least the following steps (1) to (3) when contacting a shaped zeolite body with an aqueous alkaline earth metal solution to produce an alkaline earth metal ion-exchanged zeolite shaped body: Step (1): A step of packing zeolite shaped bodies into a packing device up to a length L (m) in the direction of supply of an alkaline earth metal aqueous solution. Step (2): After step (1), an aqueous alkaline earth metal solution is supplied into the filling device, and the contact time T (hr) is set to T≧L×2.5. Step (3): After step (2), washing is performed with an aqueous medium until the pH of the washing wastewater reaches 5.5 to 9.5.

[0012] The present invention will be described in detail below.

[0013] The method for producing an alkaline earth metal ion-exchanged zeolite shaped body of the present invention produces an alkaline earth metal ion-exchanged zeolite shaped body of high quality and high ion exchange rate by going through at least the above steps (1) to (3) when contacting the zeolite shaped body with an alkaline earth metal aqueous solution to produce an alkaline earth metal ion-exchanged zeolite shaped body.

[0014] The zeolite shaped body in the present invention may be any shaped body of what is called a zeolite (crystalline aluminosilicate), and examples of such zeolites include AEL, EUO, FER, HEU, MEU, MEL, MFI, and NES types. Proton-type zeolites are preferred because they can be converted into ion-exchange zeolites more efficiently. Among these, MFI zeolites are preferred because they provide zeolite shaped bodies that can provide catalysts capable of selectively and stably producing light hydrocarbon compounds and aromatic compounds over long periods of time. MFI zeolites that satisfy the following characteristics (i) to (iv) are even more preferred. MFI zeolites refer to aluminosilicate compounds that belong to the structure code MFI defined by the International Zeolite Association.

[0015] (i) The mesopore distribution curve has a peak, the half width (hw) of the peak is hw≦20 nm, the maximum value (μ) of the peak is 10 nm≦μ≦20 nm, and the mesopore volume (pv) of the mesopores corresponding to the peak is 0.05 ml / g≦pv.

[0016] (ii) In powder X-ray diffraction measurement at a diffraction angle of 2θ, there is no peak in the range of 0.1 to 3 degrees.

[0017] (iii) The average particle diameter (PD) is PD≦100 nm.

[0018] (iv) The differential pore volume value (dVP / d(dP))-micropore distribution curve in the pore diameter range of 0.3 nm to 0.8 nm has a maximum value, and the pore diameter showing the largest differential pore volume value (dVP / d(dP)) is in the range of 0.4 to 0.5 nm.

[0019] Here, micropores are defined by IUPAC as micropores with a pore diameter of 2 nm or less. Mesopores are defined by IUPAC as mesopores with a pore diameter of 2 to 50 nm. Micropores and mesopores can be measured by a common nitrogen adsorption method at liquid nitrogen temperature. Furthermore, by analyzing the measurement results obtained by the nitrogen adsorption method, the pore volume values ​​of micropores and mesopores and the pore distribution curves can be obtained. For example, the following method can be used for this analysis.

[0020] The adsorption process of micropores is analyzed using the Saito-Foley method (AIChE Journal, 1991, Vol. 37, pp. 429-436). For example, the total pore volume of micropores can be calculated by integrating the nitrogen gas desorption volume within the range corresponding to pore diameters of 2 nm or less. Furthermore, a cumulative curve is first obtained, with the vertical axis representing the nitrogen desorption volume per unit mass (VP) (mL / g) and the horizontal axis representing the micropore diameter (dP) (nm). Then, a differential pore volume (dVP / d(dP))-micropore distribution curve is plotted, with the vertical axis representing the differential value (dVP / d(dP)) of the nitrogen gas desorption volume from micropores with respect to the micropore diameter. This allows the peak increase in the nitrogen desorption volume per unit mass at each micropore diameter to be obtained.

[0021] The desorption process of mesopores is analyzed using the Barret-Joyner-Halenda method (Journal of the American Chemical Society, 1951, pp. 373-380). For example, the total pore volume of mesopores can be obtained by integrating the amount of nitrogen gas desorbed in the range corresponding to pore diameters of 2 nm to 50 nm.

[0022] In addition, first, a cumulative curve is obtained with the nitrogen desorption amount per unit mass VP (mL / g) on ​​the vertical axis and the mesopore diameter DP (nm) on the horizontal axis, and then the vertical axis is changed to the differential value (d(VP) / d(DP)) of the nitrogen gas desorption amount from the mesopores with respect to the mesopore diameter value, and the peak of the increase in the nitrogen desorption amount per unit mass at the mesopore diameter can be obtained.

[0023] PD can be calculated from the outer surface area using the following formula (1). PD=6 / S(1 / 2.29×10 6 +0.18×10 -6 ) (1) (where S is the external surface area (m 2 / g) In addition, the external surface area (S(m 2 / g) can be calculated by the t-plot method using a general nitrogen adsorption method at liquid nitrogen temperature. For example, when t is the thickness of the adsorbed amount, measurement points in the range of 0.6 to 1 nm are linearly approximated for t, and the external surface area is calculated from the slope of the resulting regression line.

[0024] Another method for measuring the particle size of zeolite is to randomly select 10 or more particles from a photograph taken with a scanning electron microscope (SEM) or a transmission electron microscope (TEM) and determine their surface area average diameter.

[0025] The MFI zeolite has a feature that the ion exchange sites are concentrated inside the zeolite, and therefore, ion exchange proceeds more slowly than with ordinary zeolites. However, the method for producing an alkaline earth metal ion-exchanged zeolite shaped article of the present invention makes it possible to efficiently carry out alkaline earth metal ion exchange with MFI zeolite and even with its shaped article.

[0026] Zeolite is formed into a shaped zeolite body because it avoids problems such as pressure loss when it comes into contact with an alkaline earth metal aqueous solution and can simplify the molding process for subsequent industrial use. A binder may be blended into the shaped zeolite body, and examples of binders include silica binders, which provide sufficient moldability and fracture strength for the shaped zeolite body. There are no limitations on the shape of the shaped zeolite body, and cylindrical shaped zeolite bodies are preferred because they allow for the production of alkaline earth metal ion-exchanged zeolite bodies that have been ion-exchanged efficiently.

[0027] The alkaline earth metal aqueous solution in the present invention may be, for example, an aqueous solution obtained by dissolving an alkaline earth metal such as calcium, magnesium, strontium, or barium, or a salt thereof, in an aqueous medium such as pure water, distilled water, ion-exchanged water, tap water, or industrial water, with calcium aqueous solution being particularly preferred. Furthermore, examples of alkaline earth metal salts include hydroxides, acetates, and nitrates, with calcium hydroxide being particularly preferred because it has excellent ion exchange efficiency and allows for a production method in which the amount of calcium hydroxide used is reduced.

[0028] The step (1) in the method for producing an alkaline earth metal ion-exchanged zeolite shaped body of the present invention is a step of packing zeolite shaped bodies into a packing device to a length L (m) in the direction in which an aqueous alkaline earth metal solution is supplied.

[0029] The filling device used in this case may have any shape that allows the filling of zeolite shaped bodies, and its cross-sectional shape may be not only circular but also polygonal, such as triangular, rectangular, pentagonal, or hexagonal. The material used is preferably one that does not inhibit the ion exchange of alkaline earth metal ions, and examples of such materials include glass, polyvinyl chloride, and stainless steel. The filling device is preferably a large-scale filling device, particularly one with a capacity of 20 L or more, since this allows for production with industrially suitable productivity. The length L is determined by balancing with the capacity of the filling device, and is preferably 1 m or more.

[0030] Furthermore, the filling device is preferably a vertical type, as this allows for efficient ion exchange.

[0031] In the (2) step of the method for manufacturing an alkaline earth metal ion-exchanged zeolite molded body of the present invention, after the above (1) step, an aqueous alkaline earth metal solution is supplied into the filling device, and the contact time T (hr) at that time is set to T ≧ L × 2.5, which is a step of contacting. Here, when T < L × 2.5, the contact of the aqueous alkaline earth metal solution becomes insufficient, and the obtained zeolite molded body has insufficient ion exchange, making it difficult to manufacture a uniform zeolite molded body.

[0032] And the aqueous alkaline earth metal solution has no limitation on its concentration etc. as long as it is possible to prepare an alkaline earth metal ion-exchanged zeolite molded body. Among them, since it has an excellent balance between the exchange efficiency of alkaline earth metal ions and the alkaline earth metal saturation concentration and enables efficient production, 10 to 200 mmol / l is preferable, and further preferably 10 to 50 mmol / l. Also, the contact of the aqueous alkaline earth metal solution with the zeolite molded body is preferably a circulation type in order to enable homogeneous and efficient production. There is no limitation on the amount of the aqueous alkaline earth metal solution used when contacting with zeolite. Among them, in order to enable more efficient production, it is preferable to be in the range of zeolite : aqueous alkaline earth metal solution (volume ratio) = 1:!~1:5. When it is less than 1:1, it is insufficient to immerse the zeolite molded body, and when it exceeds 1:5, efficient circulation becomes difficult. Also, there is no limitation on the method, direction, etc. of supplying the aqueous alkaline earth metal solution into the filling device. Among them, since it is possible to manufacture an alkaline earth metal ion-exchanged zeolite molded body with good reproducibility using a simple device, it is preferable to supply from a position lower in the filling device. And especially since it is possible to achieve efficient ion exchange with less unevenness in ion exchange, it is preferable to supply from positions lower and upper in the filling device, and further preferably to switch between lower supply and upper supply and switch the liquid feeding direction.

[0033] It should be noted that there seems to be a typo in the original text where "1:!~1:5" should probably be "1:1~1:5". This has been maintained in the translation for consistency with the provided text.The linear flow velocity when the alkaline earth metal aqueous solution is brought into contact with the zeolite shaped body can be appropriately selected depending on the diameter of the filling device, the flow rate of the pump, etc., and is preferably 5 to 40 cm / min, and more preferably 5 to 30 cm / min, in particular to prevent cracking of the device, pulverization of the zeolite, etc. The temperature during contact is not limited as long as it allows the preparation of an alkaline earth metal ion-exchanged zeolite shaped body, and is preferably in the range of 20 to 60°C, and more preferably 25 to 45°C, in particular to enable efficient ion exchange.

[0034] The step (3) in the method for producing an alkaline earth metal ion-exchanged zeolite shaped article of the present invention is a step of washing with an aqueous medium after the step (2) above until the pH of the washing wastewater reaches 5.5 to 9.5.

[0035] Examples of the aqueous medium used in this case include those mentioned above. Washing can be performed by supplying an aqueous medium into the filling device. Circulation may be used. Washing is continued until the pH of the washing wastewater after washing falls within the range of 5.5 to 9.5. If the pH of the washing wastewater exceeds 9.5, the washing will be insufficient and the resulting zeolite shaped body will contain alkaline earth metal salts outside the crystal as alkaline earth metals other than those ion-exchanged. On the other hand, if the pH is less than 5.5, the resulting zeolite shaped body will have insufficient ion exchange.

[0036] The method for producing an alkaline earth metal ion-exchanged zeolite shaped body of the present invention may include steps of drying, calcining, etc. after step (3). However, since this is a particularly efficient method for producing an alkaline earth metal ion-exchanged zeolite shaped body, it is preferable to include step (4) in which the shaped body is dried at 100 to 120°C for 10 to 18 hours and then calcined at 530 to 570°C for 4 to 8 hours.

[0037] The method for producing an alkaline earth metal ion-exchanged zeolite shaped body of the present invention makes it possible to produce an alkaline earth metal ion-exchanged zeolite shaped body that has little unevenness in ion exchange and exhibits a substantially uniform ion exchange rate, even when produced in large quantities.

[0038] For the purpose of adjusting the acidity of the resulting alkaline earth metal ion-exchanged zeolite shaped body, the average ion exchange rate of all alkaline earth metals in the alkaline earth metal ion-exchanged zeolite shaped body is preferably 10 to 100%, and more preferably 20 to 60% in order to achieve a minimum level of acidity.

[0039] In order to obtain a uniform alkaline earth metal ion-exchanged zeolite shaped body, it is preferable that the variation in the ion exchange rate is small, and the variation can be defined, for example, as follows: variation coefficient = (maximum alkaline earth metal ion exchange rate - minimum alkaline earth metal ion exchange rate) / overall average alkaline earth metal ion exchange rate. When the alkaline earth metal aqueous solution is supplied from a fixed liquid supply direction, either lower or upper, the variation coefficient can be calculated simply by using, for example, the alkaline earth metal ion exchange rate of the alkaline earth metal ion-exchanged zeolite shaped body corresponding to 10% by weight at the supply inlet and the alkaline earth metal ion exchange rate of the alkaline earth metal ion-exchanged zeolite shaped body corresponding to 10% by weight at the supply outlet. Furthermore, when the alkaline earth metal aqueous solution is supplied by switching the liquid supply direction, the maximum alkaline earth metal ion exchange rate, the minimum alkaline earth metal ion exchange rate, and the average alkaline earth metal ion exchange rate for the entire alkaline earth metal can be calculated simply from the alkaline earth metal ion exchange rate of the alkaline earth metal ion-exchanged zeolite shaped body corresponding to 10% by weight at the supply inlet, 10% by weight at the center, and 10% by weight at the supply outlet. Note that the expressions "supply inlet" and "supply outlet" used here are used for convenience, with one being referred to as the inlet and the other as the outlet. The unevenness coefficient is preferably 0.5 or less, and smaller values ​​are preferred.

[0040] Furthermore, since this provides a high ion exchange rate of alkaline earth metals and is economical, it is preferable that the alkaline earth metal ions contained in the aqueous alkaline earth metal solution used in step (1) are ion-exchanged in an amount equivalent to 70% by weight or more. To achieve such high efficiency, it is preferable to use an aqueous calcium hydroxide solution as the aqueous alkaline earth metal salt solution.

[0041] The alkaline earth metal ion-exchanged zeolite shaped body obtained by the present invention can be used as a catalyst for producing chemical substances, a catalyst for purifying exhaust gases, etc., particularly as a catalyst for producing aromatic compounds such as benzene, toluene, xylene, trimethylbenzene, ethylbenzene, propylbenzene, butylbenzene, naphthalene, methylnaphthalene, etc., especially benzene, toluene, and xylene, from aliphatic hydrocarbons. [Effects of the Invention]

[0042] The present invention relates to a method for efficiently producing alkaline earth metal ion-exchanged zeolite shaped articles which are useful as catalysts for producing chemical substances, catalysts for purifying exhaust gases, etc. [Example]

[0043] Specific examples of the present invention will be described below as examples, but the present invention is not limited to these examples. The zeolite, zeolite shaped body, and alkaline earth metal ion-exchanged zeolite shaped body used in the examples were measured and defined by the following methods.

[0044] ~Measurement of pore distribution, pore diameter, and external surface area~ The pore distribution and pore diameter of the zeolite were measured by nitrogen adsorption measurement.

[0045] Nitrogen adsorption measurements were performed using a standard nitrogen adsorption device (product name BELSOAP-max, manufactured by BEL Japan Co., Ltd.). The adsorption side was measured at relative pressure (P / P0) intervals of 0.025. The desorption side was measured at relative pressure intervals of 0.05. The external surface area was calculated by linear approximation of the adsorption layer thickness (t = 0.6 to 1.0 nm) using the t-plot method. BELMaster (ver. 2.3.1) manufactured by BEL Japan Co., Ltd. was used to analyze the pore distribution curve.

[0046] The adsorption process of the nitrogen adsorption measurement was analyzed by the Saito-Foley method (AIChE Journal, 1991, Vol. 37, pp. 429-436), and a micropore distribution curve was obtained, with the horizontal axis representing the pore microdiameter constant and the vertical axis representing the differential value of the desorption amount of nitrogen gas.

[0047] The desorption process of the nitrogen adsorption measurement was analyzed using the Barret-Joyner-Halenda method (Journal of the American Chemical Society, 1951, pp. 373-380), and a mesopore distribution curve was obtained, with the horizontal axis representing the pore diameter constant and the vertical axis representing the differential value of the amount of desorbed nitrogen gas. The total pore volume of mesopores was calculated by integrating the amount of desorbed nitrogen gas in the range of 2 nm to 50 nm.

[0048] The largest peak of the differential value (d(V / m) / d(D)) of the amount of nitrogen gas desorbed from the mesopores with respect to the mesopore diameter was analyzed using a Gaussian function intensity approximation, and mesopores with diameters within a range of twice the standard deviation (2σ) (=μ±2σ) from the center value (μ) of the Gaussian function were defined as uniform mesopores. The pore volume of uniform mesopores was calculated by integrating the amount of nitrogen gas desorbed within a range of ±2σ based on the center value (μ).

[0049] ~Measuring average particle size~ The average particle size was calculated from the external surface area using the above formula (1). In formula (1), S is the external surface area (m 2 / g), and PD is the average particle diameter (m). The external surface area (S(m 2 / g)) was calculated by the t-plot method using the nitrogen adsorption method at liquid nitrogen temperature.

[0050] ~Measurement of SiO2 / Al2O3 molar ratio~ The SiO2 / Al2O3 molar ratio of the zeolite was determined by dissolving the zeolite in a mixed aqueous solution of hydrofluoric acid and nitric acid, and measuring the resultant solution by inductively coupled plasma atomic emission spectroscopy (ICP-AES) using a general ICP apparatus (product name OPTIMA3300DV, manufactured by PerkinElmer).

[0051] ~Powder X-ray diffraction measurement~ Measurements were taken in air using an X-ray diffraction measurement device (Spectris, product name: X'pert PRO MPD) with a tube voltage of 45 kV and a tube current of 40 mA using CuKα1. The range of 0.04 to 5 degrees was analyzed at 0.08 degree / step and 200 seconds / step. The background, corrected for the absorption rate of the direct beam, was also removed.

[0052] The presence or absence of peaks can be confirmed visually, or a peak search program can be used. A commonly used peak search program can be used. For example, the measurement results, with the horizontal axis being 2θ (degrees) and the vertical axis being intensity (au), were smoothed using the Savitsky & Golay equation and a sliding polynomial filter, and then the second derivative was calculated. If three or more consecutive negative values ​​were found, a peak was determined to be present.

[0053] ~Method for measuring acid content~ The acid amount was measured using a standard NH3-TPD device (product name BELCAT II, ​​manufactured by Microtrac-Bell Corporation) and a gas analyzer (product name BELMass, manufactured by Microtrac-Bell Corporation). The sample was granulated and placed in a cell. The temperature was raised to 500°C at 10°C / min under a helium atmosphere and held there for 1 hour. The temperature was then lowered to 100°C, and 0.2% ammonia gas was introduced for 30 minutes. The temperature was then raised to 700°C at 10°C / min, and the desorbed ammonia was analyzed using the gas analyzer. The acid amount of the sample was calculated from the remaining amount of ammonia desorbed, excluding the amount derived from weak acids.

[0054] ~Method for determining alkaline earth metal ion exchange rate~ The alkaline earth metal content was measured using an ICP apparatus (product name: Optima 8300, manufactured by PerkinElmer, Inc.). After accurately weighing the sample into a 100 ml polymer measuring flask, hydrofluoric acid, nitric acid, and ultrapure water were added and the flask was left to dissolve overnight. After measuring, an aliquot of the sample was taken and measured by ICP-AES, and the alkaline earth metal content was calculated from the calibration curve. The ion exchange rate was calculated from the calculated alkaline earth metal content and the acidity of the raw zeolite calculated by NH3-TPD.

[0055] ~Calculation method for the unevenness coefficient of alkaline earth metal ion exchange rate~ (When supplying from the bottom of the filled container (constant liquid flow direction)) The maximum alkaline earth metal ion exchange rate, minimum alkaline earth metal ion exchange rate, and overall average alkaline earth metal ion exchange rate were determined from the alkaline earth metal ion exchange rates of the alkaline earth metal ion-exchanged zeolite molded bodies corresponding to 10% by weight at the inlet and 10% by weight at the outlet of the zeolite molded body filled in the filling device for supplying the alkaline earth metal aqueous solution, and the unevenness coefficient was calculated as (= (maximum alkaline earth metal ion exchange rate (10% by weight of alkaline earth metal ion exchange rate at the inlet) - minimum alkaline earth metal ion exchange rate (10% by weight of alkaline earth metal ion exchange rate at the outlet)) / overall average alkaline earth metal ion exchange rate).

[0056] (When switching supply from the top or bottom of the filled container (switching liquid flow direction)) The maximum alkaline earth metal ion exchange rate, the minimum alkaline earth metal ion exchange rate, and the overall average alkaline earth metal ion exchange rate were determined from the alkaline earth metal ion exchange rates of the alkaline earth metal ion-exchanged zeolite molded bodies corresponding to 10% by weight at the inlet, 10% by weight at the center, and 10% by weight at the outlet of the zeolite molded body packed in the packing device for supplying the alkaline earth metal aqueous solution, and the unevenness coefficient (= (maximum alkaline earth metal ion exchange rate - minimum alkaline earth metal ion exchange rate) / overall average alkaline earth metal ion exchange rate) was calculated.

[0057] When the unevenness coefficient is 0.5 or less, it is judged that the unevenness is low and the uniformity is excellent, and when the value is small, it is judged that the uniformity is particularly excellent.

[0058] Preparation Example 1 (Preparation of Raw Zeolite) MFI type zeolite was produced by the method described in JP 2013-227203 A.

[0059] Amorphous aluminosilicate gel was added to an aqueous solution of tetrapropylammonium (hereinafter sometimes abbreviated as TPA) hydroxide and sodium hydroxide and suspended. MFI-type zeolite was added to the resulting suspension as seed crystals to prepare a raw material composition. The amount of seed crystals added was 0.7 wt% relative to the weight of Al2O3 and SiO2 in the raw material composition.

[0060] The raw material composition had the following composition: SiO2 / Al2O3 molar ratio = 48, TPA / Si molar ratio = 0.05, Na / Si molar ratio = 0.16, OH / Si molar ratio = 0.21, H2O / Si molar ratio = 10.

[0061] The obtained raw material composition was sealed in a stainless steel autoclave and crystallized for 4 days while stirring at 115°C to obtain a slurry mixture. The crystallized slurry mixture was subjected to solid-liquid separation using a centrifugal settler, and the solid particles were washed with a sufficient amount of pure water and dried at 110°C to obtain a dry powder. The obtained dry powder was dispersed in 1 mol / L hydrochloric acid, filtered, and dried. After calcination at 550°C for 1 hour in air, a calcination treatment including steam treatment at 600°C with 50% water vapor for 2 hours was performed. The obtained powder was dispersed in 1 mol / L hydrochloric acid, filtered, and washed to obtain MFI type zeolite.

[0062] The obtained MFI zeolite had an average particle size of 38 nm, a SiO2 / Al2O3 molar ratio of 55, and a total mesopore volume of 0.45 ml / g. The micropore distribution curve showed a maximum with the largest differential pore volume at a pore diameter of 0.4125 nm. The half-width of the uniform mesopore peak in the mesopore distribution curve was 16 nm, with a center value of 15 nm. The pore volume of the uniform mesopores was 0.40 ml / g, and the proportion of the pore volume of the uniform mesopores to the total pore volume was 89%. Powder X-ray diffraction of the obtained MFI zeolite showed no peak in the range of 0.1 to 3 degrees, indicating that the mesopores were irregularly connected. The acidity of the obtained MFI zeolite was 0.24 mmol / g.

[0063] Preparation Example 2 To 100 parts by weight of the MFI zeolite obtained in Preparation Example 1, 43 parts by weight of silica (manufactured by Nissan Chemical Industries, Ltd., product name Snowtex N-30G), 4 parts by weight of cellulose, and 21 parts by weight of pure water were added and kneaded. The kneaded mixture was then formed into a cylindrical molded product having a diameter of 1.5 mm and a length of 1.0 to 7.0 mm (average length 3.5 mm). This was dried overnight at 100°C to obtain a cylindrical molded product of MFI zeolite. The acid amount of the obtained molded product of MFI zeolite was 0.20 mmol / g.

[0064] Example 1 9.6 kg of the MFI zeolite compacts obtained in Preparation Example 2 was packed into a large container with an inner diameter of 10 cm. The packing length L was 2 m. Separately, 28.6 g of calcium hydroxide was dissolved in 32.0 L of pure water to prepare a 12.1 mmol / L calcium hydroxide aqueous solution. A chemical-resistant polyolefin hose was used to connect the circulation pump to the bottom of the large container, and the calcium hydroxide aqueous solution was circulated at a linear flow velocity of 26 cm / min. Thirty minutes after the start of circulation, 28.6 g of calcium hydroxide was added again to the aqueous solution tank, and the solution was circulated for a total of 6 hours. After the calcium hydroxide aqueous solution was completely removed, 32.0 L of pure water was circulated at the same linear flow velocity for 1 hour, after which the washing solution was completely removed and the pH was measured. Washing was then repeated until the pH of the washing wastewater reached 9.3. After washing, the zeolite compacts were separated into 10 wt% from the aqueous solution inlet and 10 wt% from the outlet of the container and collected separately on a porcelain dish. Together with the remaining zeolite compacts, they were heated to 110°C at a rate of 10°C / min and dried overnight. They were then calcined at 550°C for 5 hours to obtain calcium ion-exchanged MFI-type zeolite compacts.

[0065] The calcium ion-exchange rate of the obtained calcium ion-exchanged MFI zeolite compact was 35% at the inlet 10 wt% of the packed container, 22% at the outlet 10 wt%, and 29% overall on average. The unevenness coefficient between the inlet and outlet was 0.46, and the effective utilization rate of the calcium hydroxide used was 71 wt%. The results are shown in Table 1.

[0066] Example 2 The MFI zeolite shaped bodies were packed to a depth of 2 m (length L), a 12.1 mmol / L aqueous calcium hydroxide solution was circulated, the same amount of calcium hydroxide was added after 30 minutes, and the mixture was circulated for a total of 16 hours. After that, the same procedure as in Example 1 was repeated, except that the mixture was washed with pure water until the pH of the washing effluent reached 9.3, thereby obtaining calcium ion-exchanged MFI zeolite shaped bodies.

[0067] The calcium ion-exchange rate of the obtained calcium ion-exchanged MFI zeolite compact was 45% at the inlet 10 wt% of the packed container, 27% at the outlet 10 wt%, and 36% overall on average. The unevenness coefficient between the inlet and outlet was 0.48, and the effective utilization rate was 90 wt%. The results are shown in Table 1.

[0068] Example 3 The zeolite molded body was packed to 0.4 m (length L), a 12.1 mmol / L aqueous calcium hydroxide solution was circulated, the same amount of calcium hydroxide was added after 30 minutes, and the mixture was circulated for a total of 1 hour.The same procedure as in Example 1 was then repeated, except that the mixture was washed with pure water until the pH of the washing effluent reached 8.8, thereby obtaining a calcium ion-exchanged MFI zeolite molded body.

[0069] The calcium ion-exchange rate of the obtained calcium ion-exchanged MFI zeolite compact was 34% at the inlet 10 wt% of the packed container, 27% at the outlet 10 wt%, and an overall average calcium ion-exchange rate of 31%. The unevenness coefficient between the inlet and outlet was 0.20, and the effective utilization rate was 76 wt%. The results are shown in Table 1.

[0070] Example 4 The zeolite molded body was packed to 1 m (length L), a 12.1 mmol / L aqueous calcium hydroxide solution was circulated, and the same amount of calcium hydroxide was added after 30 minutes, 60 minutes, and 90 minutes. After circulating for a total of 6 hours, the same procedure as in Example 1 was repeated, except that the pH of the washing effluent was washed with pure water until it reached 9.4, and a calcium ion-exchanged MFI zeolite molded body was obtained.

[0071] The calcium ion exchange rate of the obtained calcium ion-exchanged MFI zeolite compact was 65% at the inlet 10 wt%, 47% at the outlet 10 wt%, and 56% overall. The unevenness coefficient between the inlet and outlet was 0.31, and the effective utilization rate was 72 wt%. The results are shown in Table 1.

[0072] Example 5 A calcium ion-exchanged MFI zeolite shaped body was obtained in the same manner as in Example 1, except that the MFI zeolite shaped body was packed to a depth of 2 m (length L), a 191.9 mmol / L aqueous calcium acetate solution was circulated for a total of 6 hours, and then the shaped body was washed with pure water until the pH of the washing effluent reached 5.9.

[0073] The calcium ion exchange rate of the resulting calcium ion-exchanged MFI zeolite compact at the outlet (10 wt%) was 31%, that at the outlet (10 wt%) was 22%, and the overall average calcium ion exchange rate was 27%. The unevenness coefficient between the inlet and outlet was 0.33, and the effective utilization rate was 8 wt%. The results are shown in Table 1.

[0074] Comparative Example 1 An MFI zeolite formed body was obtained in the same manner as in Example 1, except that the MFI zeolite formed body was packed to a depth of 2 m (length L), a 12.1 mmol / L aqueous calcium hydroxide solution was circulated, the same amount of calcium hydroxide was added after 30 minutes, and the mixture was circulated for a total of 3 hours, followed by washing with pure water until the pH of the washing effluent reached 9.0.

[0075] The calcium ion exchange rate of the obtained MFI zeolite compact at the inlet (10 wt%) was 44%, that at the outlet (10 wt%) was 19%, and the overall average calcium ion exchange rate was 31%. The unevenness coefficient between the inlet and outlet was 0.80, indicating a large non-uniform ion exchange, and the effective utilization rate was 77%. The results are shown in Table 1.

[0076] Comparative Example 2 The MFI zeolite shaped bodies were packed to a height of 1 m, and a 12.1 mmol / L aqueous calcium hydroxide solution was circulated. The same amount of calcium hydroxide was added after 30 minutes, 60 minutes, 90 minutes, 120 minutes, 150 minutes, 180 minutes, and 210 minutes. After circulating for a total of 6 hours, the shaped bodies were washed twice with pure water, and the pH of the effluent was 9.9. The same procedure as in Example 1 was repeated to obtain calcium ion-exchanged MFI zeolite shaped bodies.

[0077] The calcium ion exchange rate of the obtained calcium ion-exchanged MFI-type zeolite compact was 137% at the inlet 10 wt%, 110% at the outlet 10 wt%, and 124% overall, confirming that calcium was supported outside the ion exchange sites. The unevenness coefficient between the inlet and outlet was 0.22, and the effective utilization rate was 77 wt%. The results are shown in Table 1.

[0078] [Table 1]

[0079] Example 6 9.6 kg of the MFI zeolite compacts obtained in Preparation Example 2 was packed into a large container with an inner diameter of 10 cm. The packing length L was 2 m. Separately, 28.6 g of calcium hydroxide was dissolved in 32.0 L of pure water to prepare a 12.1 mmol / L calcium hydroxide aqueous solution. A circulation pump was connected to the top and bottom of the large container using a chemical-resistant polyolefin hose, and the calcium hydroxide aqueous solution was circulated at a linear flow velocity of 26 cm / min. Thirty minutes after the start of circulation, 28.6 g of calcium hydroxide was added to the aqueous solution tank again, and the solution was circulated for a total of 6 hours. During this time, calcium hydroxide aqueous solution was supplied from the top of the container from 0 to 30 minutes, and from the bottom from 30 to 360 minutes. After the calcium hydroxide aqueous solution was completely removed, 32.0 L of pure water was circulated at the same linear flow velocity for 1 hour, after which the washing solution was completely removed and the pH was measured. Washing was then repeated until the pH of the washing wastewater reached 9.3. After washing, the zeolite compacts were separated into the upper 10 wt%, middle 10 wt%, and lower 10 wt% of the packed container and collected separately on a porcelain dish. Together with the remaining zeolite compacts, they were heated to 110°C at a rate of 10°C / min and dried overnight. They were then calcined at 550°C for 5 hours to obtain calcium ion-exchanged MFI-type zeolite compacts.

[0080] The calcium ion-exchange rate of the obtained calcium ion-exchanged MFI zeolite compact was 41% in the upper 10 wt% of the packed container, 34% in the central 10 wt%, and 38% in the lower 10 wt%, for an overall average calcium ion-exchange rate of 38%. The unevenness coefficient was 0.17, and the effective utilization rate of the calcium hydroxide used was 95 wt%. The results are shown in Table 2.

[0081] Example 7 The zeolite molded body was packed up to 2 m (length L), a 12.1 mmol / L calcium hydroxide aqueous solution was circulated, and the same amount of calcium hydroxide was added after 30 minutes, 60 minutes, and 90 minutes. The calcium hydroxide aqueous solution was supplied from the top of the packed container from 0 to 60 minutes, and from the bottom from 60 to 360 minutes. After circulating for a total of 6 hours, the same procedure as in Example 6 was carried out, except that the zeolite molded body was washed with pure water until the pH of the washing effluent reached 9.4, and a calcium ion-exchanged MFI type zeolite molded body was obtained.

[0082] The calcium ion-exchange rate of the obtained calcium ion-exchanged MFI zeolite compact was 74% in the upper 10 wt% of the packed container, 74% in the central 10 wt%, and 75% in the lower 10 wt%, for an overall average calcium ion-exchange rate of 74%. The unevenness coefficient was 0.01, and the effective utilization rate of the calcium hydroxide used was 93 wt%. The results are shown in Table 2.

[0083] Example 8 The zeolite molded body was packed up to 2 m (length L), a 6.1 mmol / L aqueous calcium hydroxide solution was circulated, the same amount of calcium hydroxide was added after 30 minutes, the aqueous calcium hydroxide solution was supplied from the top of the packed container from 0 to 30 minutes, and from the bottom from 30 to 360 minutes, and after circulating for a total of 6 hours, the same procedure as in Example 6 was carried out, except that the zeolite molded body was washed with pure water until the pH of the washing wastewater reached 8.9, and a calcium ion-exchanged MFI type zeolite molded body was obtained.

[0084] The calcium ion-exchange rate of the obtained calcium ion-exchanged MFI zeolite compact was 20% in the upper 10 wt% of the packed container, 16% in the central 10 wt%, and 22% in the lower 10 wt%, for an overall average calcium ion-exchange rate of 19%. The unevenness coefficient was 0.35, and the effective utilization rate of the calcium hydroxide used was 97 wt%. The results are shown in Table 2.

[0085] Comparative Example 3 The zeolite molded body was packed up to 2 m (length L), a 12.1 mmol / L aqueous calcium hydroxide solution was circulated, the same amount of calcium hydroxide was added after 30 minutes, the aqueous calcium hydroxide solution was supplied from the top of the packed container from 0 to 30 minutes, and from the bottom from 30 to 180 minutes, and after circulating for a total of 3 hours, the calcium hydroxide aqueous solution was supplied from the bottom. Except for this, the zeolite molded body was washed with pure water until the pH of the washing effluent reached 9.2, and a calcium ion-exchanged MFI zeolite molded body was obtained in the same manner as in Example 6.

[0086] The calcium ion-exchange rate of the obtained calcium ion-exchanged MFI zeolite compact was 42% in the upper 10 wt% of the packed container, 21% in the central 10 wt%, and 47% in the lower 10 wt%, for an overall average calcium ion-exchange rate of 37%. The unevenness coefficient was 0.71, indicating a large degree of non-uniform ion exchange, and the effective utilization rate of the calcium hydroxide used was 93 wt%. The results are shown in Table 2.

[0087] [Table 2] [Industrial Applicability]

[0088] The present invention relates to a method for producing an alkaline earth metal ion-exchanged zeolite shaped body, and in particular to a method for producing an alkaline earth metal ion-exchanged zeolite shaped body that can uniformly contain alkaline earth metals at a high exchange rate in the filled zeolite shaped body when the zeolite shaped body is ion-exchanged with alkaline earth metals using large-scale equipment, and is therefore industrially useful.

Claims

1. When a shaped zeolite body is brought into contact with an aqueous alkaline earth metal solution to produce an alkaline earth metal ion-exchanged zeolite body, the process includes at least the following steps (1) to (3): A method for producing an alkaline earth metal ion-exchanged zeolite shaped body, wherein in the step (2), when the aqueous alkaline earth metal solution is supplied to the zeolite shaped body, the aqueous alkaline earth metal solution is supplied in a circulating manner and the supply direction is changed. Step (1): A step of packing zeolite shaped bodies into a packing device up to a length L (m) in the direction of supply of an aqueous alkaline earth metal solution. Step (2): After step (1), supply an aqueous alkaline earth metal solution into the filling device, with a contact time T (hr) of T≧L×2.

5. Step (3): After step (2), washing is performed with an aqueous medium until the pH of the washing wastewater reaches 5.5 to 9.

5.

2. 2. The method for producing an alkaline earth metal ion-exchanged zeolite shaped body according to claim 1, wherein the zeolite constituting the shaped body is a proton-type zeolite, and the alkaline earth metal aqueous solution in step (2) is an aqueous solution of an alkaline earth metal salt hydroxide.

3. 3. The method for producing a shaped alkaline earth metal ion-exchanged zeolite body according to claim 1, wherein the shaped zeolite body has a cylindrical shape.

4. 4. The method for producing a shaped alkaline earth metal ion-exchanged zeolite body according to claim 1, wherein the alkaline earth metal aqueous solution in step (2) has a concentration in the range of 10 to 200 mmol / L.

5. 5. The method for producing an alkaline earth metal ion-exchanged zeolite shaped body according to claim 1, wherein in step (2), the aqueous alkaline earth metal solution is supplied from a lower portion of the filling device when contacting the zeolite shaped body.

6. 6. The method for producing a shaped alkaline earth metal ion-exchanged zeolite body according to claim 1, wherein the packing device is a large-scale packing device having a diameter of 10 cm or more and a length L of 1 m or more.

7. The method for producing an alkaline earth metal ion-exchanged zeolite shaped article according to any one of claims 1 to 6, further comprising the following step (4): Step (4): After step (3), the mixture is dried at 100 to 120°C for 10 to 18 hours, and then fired at 500 to 600°C for 4 to 8 hours.

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