JP5261875B2 - Aluminophosphate zeolite adsorbent comprising oxygen 6-membered ring, production method thereof and use thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adsorbent which has large effective capacity for adsorbing water and excellent durability and is used for a heat pump, a desiccant air conditioner, a humidity-controllable wall material and a humidity-controllable sheet. <P>SOLUTION: The adsorbent comprises zeolite containing at least Al and P as elements constituting a skeleton thereof, wherein the zeolite has pores of 2.0-3.0 angstroms diameter and a three-dimensional structure consisting of an oxygen-containing six-member ring and, particularly, the zeolite has an SOD structure or an AST structure. Acicular or columnar zeolite produced by subjecting zeolite having an ERI structure to phase transition is preferably used as the adsorbent. The adsorbent is used excellently for the heat pump, particularly, for the desiccant air conditioner, the humidity-controllable wall material and the humidity-controllable sheet. <P>COPYRIGHT: (C)2007,JPO&amp;INPIT

Description

  The present invention relates to an aluminophosphate zeolite useful as an adsorbent for heat pumps, desiccant air conditioners, humidity control wall materials, humidity control sheets, and a method for producing the same.

  As a heat pump using an aluminophosphate-based zeolite adsorbent, there are many zeolites with a pore size of 3 mm or more (the pore entrance is substantially synonymous with an oxygen 8-membered ring or more) and the pores are connected in two or more dimensions. Proposed.

  For example, SAPO-34 (CHA structure; having an 8-membered oxygen ring with a pore diameter of 3.8 × 3.8 angstrom; the pore is three-dimensional), ALPO-34 (CHA structure; pore diameter 3.8 × 3.8) Examples include 8 angstrom oxygen 8-membered rings; pores are three-dimensional), ALPO-18 (AEI structure; pore diameter 3.8 × 3.8 angstrom oxygen eight-membered rings; pores are three-dimensional) (See Patent Documents 1 and 2.) However, these zeolites have a small pore size of 3 angstroms or more, and thus have low stability and low durability. In addition, ALPO-5 (AFI structure) has been proposed as a zeolite with a pore diameter of 3 angstroms or more and a one-dimensional pore. However, since the amount of adsorption varies greatly at high relative humidity, Not suitable (Patent Document 2). This is considered to be because the pore diameter of ALPO-5 is too large as 7.3 × 7.3 angstrom.

  Further, in Patent Document 2, “the amount of water adsorbed changes when the relative vapor pressure changes by 0.15 in the range of the relative vapor pressure of 0.05 to 0.30 in the water vapor adsorption isotherm measured at 25 ° C. "Adsorbent for adsorption heat pump consisting of an adsorbent having a relative vapor pressure range of 0.18 g / g or more" has been proposed, but only SAPO-34 was shown in the examples.

  Furthermore, regarding adsorbents for heat pumps comprising zeolite containing aluminum, phosphorus and iron, Patent Documents 3 and 4 describe the structure of many aluminophosphate zeolites, but the relationship between pore size and durability. Sex has not been studied.

  Conventionally, silica gel is generally used as an adsorbent in a desiccant air conditioner also called an open heat pump. As an open-type heat pump using an aluminophosphate-based zeolite adsorbent, in Patent Document 5, ALPO-5 (having an oxygen 12-membered ring having a pore diameter of 7.3 × 7.3 angstroms) is exemplified. Since the amount of adsorption varies greatly with relative humidity, it is difficult to use as with a heat pump, and its practical value for desiccant air conditioning has not been sufficient.

  For the humidity control wall material and humidity control sheet, an adsorbent having an autonomous humidity control function is used, and Patent Document 6 proposes an aluminosilicate porous material, etc., but the performance and durability are sufficient. I could not say.

  As described above, the aluminophosphate-based zeolite adsorbent having a pore diameter of 3 angstroms or more (substantially synonymous with a pore inlet having an oxygen 8-membered ring or more) and having pores connected in two or more dimensions has low structural stability. The durability as an adsorbent for heat pumps, desiccant air conditioners, humidity control wall materials, and humidity control sheets was low, and the practical value was insufficient.

JP 2002-372332 A Japanese Patent Laid-Open No. 2003-114067 JP 2004-136269 A (page 7, lines 43-49) Japanese Patent Laying-Open No. 2005-205331 (page 8, lines 37-42) Japanese Patent Laid-Open No. 11-137947 (21st line, lines 39-41) Japanese Patent Laid-Open No. 9-294931 (2nd row, 2nd row to 7th row)

  In order to solve the problems of the prior art, the object of the present invention is a heat pump, a desiccant air conditioner, a humidity control wall material, and a humidity control sheet having a large effective adsorption amount of water and excellent durability. It is in providing the adsorption agent of this and its manufacturing method.

  In order to solve the problems of the prior art, the present inventors have conducted extensive studies on the structure, composition, moisture adsorption / desorption characteristics, and durability by cycle tests of aluminophosphate-based zeolite. As a zeolite having a large amount and excellent durability, it contains at least Al and P as elements constituting the framework from among aluminophosphate-based zeolites, and the pores have a diameter of 2.0 to 3.0 angstroms. It has been found that a zeolite having a three-dimensional structure composed of a six-membered ring of oxygen, for example, a zeolite having an SOD structure containing at least Al and P has a large effective adsorption amount of water and has excellent durability. Has been found to be useful as an adsorbent for heat pumps, especially for desiccant air conditioning, humidity control wall materials, and humidity control sheets. Invention has been completed.

  Hereinafter, the present invention will be described in detail.

  The zeolite of the present invention is a zeolite having a three-dimensional structure including at least Al and P as elements constituting the skeleton and having pores of oxygen 6-membered rings having a diameter of 2.0 to 3.0 angstroms.

  Examples of the zeolite include zeolite having an SOD structure and zeolite having an AST structure.

  In the present invention, the element constituting the skeleton refers to an element constituting the zeolite skeleton other than oxygen, and does not include so-called exchange cations or supported components.

  The zeolite of the present invention must contain at least Al and P as elements constituting the framework. By including at least Al and P, an excellent characteristic as an adsorbent that an effective adsorption amount of an adsorbate such as water is increased is exhibited. Elements other than Al and P may be included, and the types of elements when included are not particularly limited. For example, Si, Fe, Li, Be, B, Mg, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Ga, Ge, etc. can be illustrated. Among these, Si, Fe, B, Ga, and Ge are preferable from the viewpoint of durability, and Si is most preferable. These elements may be included singly or two or more elements may be included at the same time.

  Moreover, although the quantity of elements other than Al and P is not particularly limited, when the element other than Al and P is M, the ratio of M (M / (Al + P + M) molar ratio) is 0.4 or less. The larger the proportion of M, the smaller the effective amount of water adsorbed, so 0.2 or less is preferable, 0.1 or less is particularly preferable, and 0, that is, an element containing no elements other than Al and P is most preferable.

  The zeolite of the present invention has a three-dimensional structure consisting of a 6-membered oxygen ring having a pore diameter of 2.0 to 3.0 angstroms.

  In the present invention, the pore diameter is defined as the diameter when the pore shape is circular, and as the average of the major and minor diameters when it is elliptical. In the case of a zeolite having a plurality of pores, the diameter of the largest pore among them is defined as the pore diameter.

  The zeolite of the present invention is preferably “a zeolite having a three-dimensional structure comprising at least Al and P as elements constituting the skeleton and having pores of oxygen 6-membered rings having a diameter of 2.0 to 3.0 angstroms” A specific example is zeolite having an SOD structure. The SOD structure is defined as a structure described in a publication (“ATLAS OF ZEOLITE FRAMEWORK TYPES (5th revised edition)”, pages 254 to 255, publisher: ELSEVIER, publication year: 2001).

  The SOD structure zeolite composed of Al and P is called ALPO-SOD or ALPO-20, and the SOD structure zeolite composed of Al, P and Si is called SAPO-20.

  The SOD structure consists of an oxygen 6-membered ring with a pore size of 2.2 × 2.2 angstroms and is 3 angstroms or less (“ZEOLITE MOLECULAR SIEVES” Author: DW Breck, p. 155, Publisher: KRINGER PUBLISHING COMPANY, publication year: 1984). Therefore, the SOD structure is considered to have high stability, and durability as an adsorbent for heat pumps, desiccant air conditioning, humidity control wall materials, and humidity control sheets is also increased.

  On the other hand, other aluminophosphate-based zeolites, ALPO-34 having a large ring having an oxygen 8-membered ring or more (CHA structure; having an 8-membered oxygen ring having a pore size of 3.8 × 3.8 angstroms), ALPO-18 (AEI structure; having an 8-membered oxygen ring with a pore size of 3.8 × 3.8 angstroms) has low stability and low durability.

  Among the aluminophosphate-based zeolites, other suitable examples of the zeolite of the present invention include zeolite having an AST structure. This zeolite is described in a publication (“ATLAS OF ZEOLITE FRAMEWORK TYPES (5th revised edition)”, p. 58-59, publisher: ELSEVIER, publication year: 2001). The AST structure is a three-dimensional structure having a six-membered oxygen ring with pores having a diameter of about 2.2 × 2.2 angstroms.

  An AST-structured zeolite composed of Al and P is called ALPO-16, and an AST-structured zeolite composed of Al, P, and Si is called SAPO-16.

  The crystal shape of the zeolite of the present invention is not particularly limited. For example, a spherical shape, a cubic shape, a plate shape, a needle shape, a column shape, and the like can be exemplified. Among these shapes, a needle shape and a column shape are preferable because a space between crystals is large and an adsorption / desorption rate of an adsorbate such as water is increased.

  Although it does not specifically limit as a particle diameter of the crystal | crystallization of the zeolite of this invention, 0.01 micrometer-100 micrometers can be illustrated, and 0.1 micrometer-10 micrometers are preferable. If it is smaller than 0.1 μm, the stability is lowered, and if it is larger than 10 μm, the diffusion rate in the crystal becomes slow, which is not preferable.

  The method for producing the zeolite of the present invention is not particularly limited. For example, a zeolite having an SOD structure, which is one of the zeolites of the present invention, can be produced by phase transition of ERI-structured zeolite in addition to direct synthesis. . The SOD structure zeolite obtained by phase transition of the ERI structure is particularly preferable because the crystal shape is a needle-like or columnar zeolite.

  The method for synthesizing the zeolite having the ERI structure is not limited, but quinuclidine, neopentylamine, cyclohexyl are used as the organic SDA shown in Examples 42 to 44 of JP-B-1-57041 and Examples 25-26 of JP-B-3-72010. Examples thereof include a method using amine and piperidine. Among these, a method using cyclohexylamine as an organic SDA (Structure Directing Agent) is preferable because it is inexpensive.

  As a method for phase transition of ERI-structured zeolite to SOD structure, hydrothermally-treating ERI-structured zeolite from which organic SDA has been removed by heat treatment in nitrogen or air or contact with acid such as hydrochloric acid or sulfuric acid. Can be illustrated.

  Examples of the hydrothermal treatment method include repeated treatment of water adsorption / desorption. For example, contacting a zeolite having an ERI structure with a gas having a high relative humidity (adsorption) and then making a phase transition to the SOD structure by repeatedly contacting the gas with a low relative humidity or increasing the temperature of the zeolite (desorption). Can do.

  SOD crystals obtained by phase transition of ERI-structured zeolite are acicular and columnar. Since the SOD structure is a cubic crystal, the crystal shape cannot be formed into a needle shape or a column shape by a normal synthesis method, but becomes a cubic shape, a spherical shape, or the like. Due to the shape of the needle-like and columnar crystals, an excellent effect is expected in which the gaps between the crystals are increased and the adsorption / desorption rate of adsorbate such as water is increased.

  On the other hand, as a method of directly synthesizing a zeolite having an SOD structure, as organic SDA, a method using TMAOH (tetramethylammonium hydroxide), a method using a mixed solution of TMAOH and TPAOH (tetrapropylammonium hydroxide), DMF A method using (dimethylformamide) can be exemplified. Among these, the method using TMAOH or DMF as the organic SDA is preferable because it is inexpensive.

  When an aluminum source, a phosphorus source, the organic SDA shown above, water, and an element other than Al and P are included, a compound of the element, and in some cases, an acid such as hydrofluoric acid or hydrochloric acid is uniformly mixed. SOD structure zeolite can be synthesized by maintaining the temperature for a predetermined time. Examples of the aluminum source include pseudo boehmite, and examples of the phosphorus source include phosphoric acid.

  Examples of a method for removing organic SDA from zeolite having an SOD structure include heat treatment in nitrogen or air, or treatment by contact with an acid such as hydrochloric acid or sulfuric acid.

  Moreover, the zeolite which has AST structure which is 1 type of the zeolite of this invention can synthesize | combine quinuclidine as organic SDA.

  When an aluminum source, phosphorus source, quinuclidine, water, and an element other than Al and P are included, a compound of the element, and in some cases, an acid such as hydrofluoric acid or hydrochloric acid is uniformly mixed and maintained at a predetermined temperature for a predetermined time. By doing so, a zeolite having an AST structure can be synthesized. Examples of the aluminum source include pseudo boehmite, and examples of the phosphorus source include phosphoric acid.

  The adsorbent comprising the zeolite of the present invention is an adsorbent whose main component is zeolite. Zeolite may be used as a powder or may be a powder slurry coated on a honeycomb rotor or the like by an appropriate method. An appropriate amount of a binder or a molding aid may be mixed with the zeolite powder to form a granular molded body. Moreover, it may be integrally formed with other materials, and may be formed into a sheet by mixing with paper or resin.

  The shape of the granular molded body is not particularly limited, and the shape and size are selected in consideration of the size and packing density of the container of the system to be used. The binder used in this case is not particularly limited, but it is preferable to devise a method for increasing the thermal conductivity in order to efficiently perform heat exchange. As the amount of binder added increases, the amount of adsorbent adsorbed per weight and volume decreases. Therefore, the smaller the mixing ratio of the binder, the better. However, it is preferable to adjust the binder so as to have a strength that can withstand the use conditions.

  The granular molded body may be a binderless molded body. Binderless molded bodies are more suitably used because they have a higher zeolite content than ordinary molded bodies and a large effective adsorption amount per unit amount of granular molded bodies.

  The adsorbent comprising the zeolite of the present invention can be used in heat pumps using low-temperature exhaust heat such as car air conditioners and fuel cells. The adsorbate is preferably water that has a large latent heat of vaporization and is safe and inexpensive.

  For example, when used as a heat pump for a car air conditioner, the exhaust heat is 80 to 100 ° C., the low temperature heat is 30 to 45 ° C., and the generated cold heat is about 5 to 10 ° C. At this time, the phase humidity at the time of adsorption is 9 to 29 %, Relative humidity at the time of desorption corresponds to 5 to 20%. Therefore, it is desirable that the amount of adsorption of the adsorbent varies greatly around 16%, which is the center of the relative humidity during adsorption and desorption.

  The zeolite used in the present invention can maintain high heat pump performance even when low exhaust heat is used. In addition, since the crystals are very stable against water adsorption / desorption, the zeolite structure hardly changes even when the cycle of moisture adsorption and heat regeneration is repeated, and the effective adsorption amount hardly decreases.

  The adsorbent comprising the zeolite of the present invention can be used as an adsorbent for a desiccant air conditioner, which is also called an open heat pump. A honeycomb rotor coated with zeolite is combined with a heat exchanger, cooler, heater, etc., so that it is used as an air conditioner mainly for dehumidification purposes. The zeolite used in the present invention can sufficiently desorb water from the honeycomb rotor even at a low heating temperature.

  The adsorbent comprising the zeolite of the present invention can be used for humidity control wall materials and humidity control sheets. When the humidity is high, water is adsorbed, and when the humidity is low, water is desorbed, so the humidity can be adjusted autonomously. The adsorbent comprising the zeolite of the present invention is characterized in that it can be adjusted at a lower humidity (5 to 35%) than a porous material such as an existing aluminosilicate. In addition, the amount of water adsorbed relative to the relative humidity changes abruptly at a certain relative humidity, so that the autonomous humidity adjustment function is large.

  Since the adsorbent comprising the zeolite of the present invention has a large effective adsorption amount of water and has excellent durability, it should be used as an adsorbent for heat pumps, desiccant air conditioners, humidity control wall materials, and humidity control sheets. Can do. Further, a zeolite adsorbent having a particularly high adsorption / desorption rate can be produced by a method of phase transition of zeolite having an ERI structure to an SOD structure.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail using an Example, this invention is not limited to these.

  All water adsorption characteristics were evaluated at 350 ° C. under reduced pressure for 2 hours, and then the water adsorption isotherm at 25 ° C. was measured by the spring balance method to determine the effective adsorption amount based on the difference between 5% and 25% relative humidity.

  Further, powder X-ray diffraction was measured using MXP3 manufactured by Mac Science, and scanning electron microscope observation was performed using JSM-T220A manufactured by JEOL.

Example 1
[ALPO-SOD synthesized by phase transition of ALPO-ERI]
ALPO-17 (ALPO-ERI) was synthesized by the following procedure. Pseudoboehmite (Al ₂ O ₃ = 74%): 8.63 g, 85% phosphoric acid: 14.4 g, cyclohexylamine: 6.20 g, water: 37.2 g were uniformly mixed, and the autoclave was used at 200 ° C. X 168 hours static synthesis. The obtained solid was filtered, washed with water, and calcined at 550 ° C. for 4 hours (1 hour under nitrogen flow + 3 hours under air flow) to remove cyclohexylamine.

  Next, using a water adsorption / desorption device (equipment No. 1) comprising a dryer and an evaporator of water, ALPO was used under the conditions of adsorption: 40 ° C., relative humidity 38%, desorption: 90 ° C., and relative humidity 2%. -17 water absorption / desorption treatment was performed. A sample after 200 cycles was evaluated by powder X-ray diffraction. As a result, an SOD structure in which a small amount of the ERI structure coexisted (zeolite having a three-dimensional structure consisting of a six-membered oxygen ring having a pore size of 2.2 × 2.2 angstroms). ) Was confirmed (FIG. 1). When the shape of the crystal was observed with a scanning electron microscope, it was a needle-like crystal (FIG. 2).

  When the initial moisture adsorption isotherm of the obtained ALPO-SOD was measured, the amount of adsorption changed greatly at a relative humidity of 18%. Moreover, the effective adsorption amount by the difference of 5% and 25% of relative humidity was 20.0 (g / 100g) (FIG. 3).

  Next, the apparatus No. Using the water adsorption / desorption apparatus No. 1, a cycle durability test was repeated with adsorption: 40 ° C., relative humidity 38%, desorption: 90 ° C., and relative humidity 2%. When the samples after 300 cycles and 500 cycles were evaluated by powder X-ray diffraction, only the SOD structure could be confirmed. Moreover, when the moisture adsorption isotherm after the cycle durability test of the obtained ALPO-SOD was measured, the effective adsorption amount due to the difference between the relative humidity of 5% and 25% was 300 cycles: 20.0 (g / 100 g), No significant change was observed at 500 cycles: 21.7 (g / 100 g) (FIG. 3).

Example 2
[ALPO-SOD synthesized by phase transition of ALPO-ERI]
ALPO-17 after removal of cyclohexylamine obtained in Example 1 was adsorbed at 90 ° C. and 30% relative humidity using a water adsorption / desorption device (device No. 2) comprising a pressure vessel, a vacuum pump, and a thermostatic bath. Desorption: Water adsorption / desorption treatment was repeated at 90 ° C. and 3% relative humidity. A sample after 1200 cycles was evaluated by powder X-ray diffraction. As a result, an SOD structure in which a small amount of ERI structure coexisted (zeolite having a three-dimensional structure composed of a six-membered oxygen ring having a pore size of 2.2 × 2.2 angstroms). ) Was confirmed (FIG. 4). Moreover, when the shape of the crystal was observed with a scanning electron microscope, it was a needle-like crystal.

  When the initial moisture adsorption isotherm of the obtained ALPO-SOD was measured, the adsorption amount greatly changed at a relative humidity of 16%. The effective adsorption amount due to the difference between 5% and 25% relative humidity was 23.5 (g / 100 g) (FIG. 5).

Example 3
[ALPO-SOD synthesized by phase transition of ALPO-ERI]
ALPO-17 after removal of cyclohexylamine obtained in Example 1 was adsorbed using a water adsorption / desorption apparatus (apparatus No. 3) comprising a muffle furnace, a steam line, and a dehumidified air line: 120 ° C., relative humidity 50 %, Desorption: Water adsorption / desorption treatment was repeated at 120 ° C. and a relative humidity of 5% or less. A sample after 100 cycles was evaluated by powder X-ray diffraction. As a result, an SOD structure in which a small amount of the ERI structure coexisted (zeolite having a three-dimensional structure composed of a 6-membered oxygen ring having a pore size of 2.2 × 2.2 angstroms). ) Was confirmed. Moreover, when the shape of the crystal was observed with a scanning electron microscope, it was a needle-like crystal.

  When the initial moisture adsorption isotherm of the obtained ALPO-SOD was measured, the adsorption amount greatly changed at a relative humidity of 17%. The effective adsorption amount due to the difference between 5% and 25% relative humidity was 23.6 (g / 100 g) (FIG. 6).

Examples 4 and 5
[SAPO-SOD synthesized by phase transition of SAPO-ERI (Si: 2, 7%)]
First, SAPO-17 (SAPO-ERI; Si: 2, 7%) was synthesized by the following procedure. Aluminum isopropoxide: 17.9 g, 85% phosphoric acid: 10.1 g, silica sol (SiO ₂ = 40%): 0.66 or 1.97 g, cyclohexylamine: 4.34 g, 47% hydrofluoric acid: 1.86 g Water: 28.2 or 27.4 g was mixed uniformly and rotated and synthesized at 200 ° C. for 24 hours using an autoclave. The obtained solid was filtered, washed with water, and calcined at 550 ° C. for 4 hours (1 hour under nitrogen flow + 3 hours under air flow) to remove cyclohexylamine.

  Next, the device No. 2 was used for water adsorption / desorption treatment of SAPO-17 under the conditions of adsorption: 90 ° C., relative humidity 30%, desorption: 90 ° C., and relative humidity 3%. A sample after 1200 cycles was evaluated by powder X-ray diffraction. As a result, an SOD structure in which a small amount of ERI structure coexisted (zeolite having a three-dimensional structure composed of a six-membered oxygen ring having a pore size of 2.2 × 2.2 angstroms). ) Was confirmed (FIG. 7). Moreover, when the crystal shape was observed with a scanning electron microscope, it was a columnar crystal (FIGS. 8 and 9).

  When the initial moisture adsorption isotherm of the obtained SAPO-SOD was measured, the adsorption amount changed greatly at a relative humidity of 15%. Also, the effective adsorption amount due to the difference between 5% and 25% relative humidity was 20.4 (g / 100 g) for Si: 2% product and 18.4 (g / 100 g) for Si: 7% product ( FIG. 10).

Reference example 1
[ALPO-SOD synthesized using TMAOH + TPAOH]
Pseudoboehmite (Al ₂ O ₃ = 74%): 9.95 g, 85% phosphoric acid: 16.6 g, tetramethylammonium hydroxide pentahydrate: 6.63 g, 40% tetrapropylammonium hydroxide: 18.0 g Water: 40.3 g was uniformly mixed, and ALPO-SOD was synthesized by standing at 200 ° C. for 16 hours. The obtained ALPO-SOD was baked at 620 ° C. for 4 hours (1 hour under nitrogen flow + 3 hours under air flow) to remove organic SDA.

  When the sample was evaluated by powder X-ray diffraction, an SOD structure (zeolite having a three-dimensional structure consisting of a 6-membered oxygen ring having a pore size of 2.2 × 2.2 angstroms) could be confirmed, and a scanning electron microscope When the crystal shape was observed, the crystals were spherical to cubic (FIG. 11).

  When the initial moisture adsorption isotherm of the obtained ALPO-SOD was measured, the adsorption amount greatly changed at a relative humidity of 15%. The effective adsorption amount due to the difference between 5% and 25% relative humidity was 16.6 (g / 100 g) (FIG. 12).

Comparative Example 1
[ALPO-34]
Based on JP-A-9-294931, ALPO-34 was synthesized at 200 ° C. for 240 hours using morpholine as organic SDA. The obtained ALPO-34 was calcined at 560 ° C. for 7 hours (1 hour under nitrogen flow + 6 hours under air flow) to remove morpholine.

  When the sample was evaluated by powder X-ray diffraction, a CHA structure (having an oxygen 8-membered ring having a pore diameter of 3.8 × 3.8 angstroms) was confirmed.

  When the initial moisture adsorption isotherm of the obtained ALPO-34 was measured, the adsorption amount changed greatly at a relative humidity of 6%. Moreover, the effective adsorption amount by the difference of 5% and 25% of relative humidity was 27.9 (g / 100g) (FIG. 13).

  Next, the apparatus No. Using the water adsorption / desorption apparatus No. 1, a cycle durability test was repeated with adsorption: 40 ° C., relative humidity 38%, desorption: 90 ° C., and relative humidity 2%. When the samples after 200 cycles and 500 cycles were evaluated by powder X-ray diffraction, only the CHA structure could be confirmed, but a decrease in peak intensity was observed. Moreover, when the moisture adsorption isotherm after the cycle durability test of the obtained ALPO-34 was measured, the effective adsorption amount due to the difference between the relative humidity of 5% and 25% was 200 cycles: 19.9 (g / 100 g), 500 cycles: decreased to 12.0 (g / 100 g) as the number of cycles increased (FIG. 13).

Powder X-ray diffraction pattern of ALPO-SOD prepared in Example 1 Scanning electron micrograph of ALPO-SOD prepared in Example 1 ALPO-SOD water adsorption isotherm prepared in Example 1 Powder X-ray diffraction pattern of ALPO-SOD prepared in Example 2 Water adsorption isotherm of ALPO-SOD prepared in Example 2 Water adsorption isotherm (25 ° C.) of ALPO-SOD prepared in Example 3 Powder X-ray diffraction pattern of SAPO-SOD prepared in Examples 4 and 5 Scanning electron micrograph of SAPO-SOD (Si 2%) prepared in Example 4 Scanning electron micrograph of SAPO-SOD (Si 7%) prepared in Example 5 SAPO-SOD water adsorption isotherm (25 ° C.) prepared in Examples 4 and 5 Scanning electron micrograph of ALPO-SOD prepared in Reference Example 1 Water adsorption isotherm of ALPO-SOD prepared in Reference Example 1 (25 ° C) Water adsorption isotherm (25 ° C.) of ALPO-34 prepared in Comparative Example 1

Claims (3)

Phase transition of ERI-structured zeolite to SOD structure with a three-dimensional structure consisting of oxygen 6-membered rings containing at least Al and P as the elements constituting the skeleton and pores of 2.0 to 3.0 angstroms in diameter A water adsorbent made of zeolite having a needle-like or columnar shape. The water adsorbent according to claim 1, comprising a zeolite containing Si in addition to Al and P as an element constituting the skeleton. Use of any 1 type chosen from the group of the heat pump which uses the water adsorbent of Claim 1 or 2, a desiccant air conditioning, a humidity control wall material, and a humidity control sheet.

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