JP4589044B2 - Dehumidifier and dehumidifying member - Google Patents

Description

  The present invention relates to a dehumidifying agent comprising a zeolite generally having a framework structure called Y-type, wherein the counter ion at the acid site is sodium (hereinafter referred to as sodium Y-type zeolite), and the Y-type The present invention relates to a dehumidifying member on which zeolite is supported.

  Currently, many dehumidifying apparatuses that perform dehumidification continuously perform dehumidification of air to be treated with a dehumidifying agent and regeneration of the dehumidifying agent that has adsorbed moisture. Therefore, the dehumidifying agent used in the dehumidifying apparatus has not only the ability to adsorb and remove moisture in the air to be treated (hereinafter referred to as moisture absorbing performance), but also the ability to desorb the adsorbed moisture (hereinafter referred to as moisture absorbing performance). , Described as dehumidifying performance).

  Silica gel is mentioned as a dehumidifying agent which is excellent in both the adsorption performance and the dehumidifying performance, and is widely used as a dehumidifying agent for a dehumidifying apparatus used for general industrial use.

  However, silica gel exhibits excellent moisture absorption performance in air with high absolute humidity, but hardly absorbs moisture and does not exhibit moisture absorption performance in air with low absolute humidity. Therefore, for example, silica gel cannot be used as a dehumidifier for a dehumidifier used when drying laundry indoors in winter when absolute humidity is low.

  Zeolite is known as a substance capable of adsorbing moisture in the air having a low absolute humidity. Examples of the zeolite include Y-type zeolite, X-type zeolite, and A-type zeolite. Among these, Y-type zeolite can desorb moisture at a lower temperature than X-type zeolite or A-type zeolite. It is considered to be most suitable as a dehumidifying agent for a dehumidifying apparatus that continuously dehumidifies.

  In general, the Y-type zeolite obtained by synthesis is a sodium Y-type zeolite in which the cation serving as a counter ion at the acid point of the zeolite is a sodium ion. The sodium Y-type zeolite has a high moisture absorption rate even in air with a low absolute humidity, and exhibits excellent moisture absorption performance.

  However, the sodium Y-type zeolite has a problem that the dehumidification performance is not sufficient. Specifically, in order to regenerate the dehumidifying performance of the sodium Y-type zeolite by dehumidification by heating, a large amount of heat energy is required, and thus there is a problem that the running cost increases.

Therefore, conventionally, the sodium ion of the sodium Y-type zeolite has been ion-exchanged with another cation to adjust the balance between the hygroscopic performance and the dehumidifying performance of the Y-type zeolite. For example, Japanese Patent Laid-Open No. 2001-239156 discloses a Y-type zeolite obtained by ion-exchanging the sodium Y-type zeolite with a metal ion other than sodium.
JP 2001-239156 A

  However, although the Y-type zeolite ion-exchanged with metal ions other than sodium has better dehumidification performance than sodium Y-type zeolite, there is a problem that the hygroscopic performance gradually decreases when moisture adsorption and desorption is repeated. there were.

  Accordingly, an object of the present invention is to exhibit excellent hygroscopic performance and dehumidifying performance even in the air with low absolute humidity, and to maintain hygroscopicity when repeated moisture adsorption and desorption (hereinafter, repeated dry and wet) The object is to provide a dehumidifying agent and a dehumidifying member that are excellent in durability.

  As a result of intensive studies to solve the above-described problems in the prior art, the present inventors set the specific physical properties of the sodium Y-type zeolite within a specific range, so that the dehumidification performance of the sodium Y-type zeolite is improved. As a result, it was found that the balance between moisture absorption performance and dehumidification performance was improved, and the present invention was completed.

That is, the present invention (1) includes the following general formula (1):
_{xNa 2 O · Al 2 O 3} · ySiO 2 · zH 2 O (1)
Y having a SiO ₂ / Al ₂ O ₃ molar ratio of 4.0 to 6.0, a Na ₂ O / Al ₂ O ₃ molar ratio of 0.5 to 1.0, and an average particle size of 3 μm or less. The present invention provides a dehumidifying agent characterized by being a type zeolite.

The following general formula (1):
_{xNa 2 O · Al 2 O 3} · ySiO 2 · zH 2 O (1)
Y having a SiO ₂ / Al ₂ O ₃ molar ratio of 4.0 to 6.0, a Na ₂ O / Al ₂ O ₃ molar ratio of 0.5 to 1.0, and an average particle size of 3 μm or less. The present invention provides a dehumidifying member characterized in that type zeolite is supported on a carrier.

  The dehumidifying agent and dehumidifying member of the present invention have a good balance between moisture absorption performance and dehumidification performance, and are excellent in repeated dry and wet durability, so that moisture in the air with low absolute humidity can be removed well. In addition, the running cost can be reduced.

The dehumidifying agent of the present invention is a Y-type zeolite having a skeletal structure generally referred to as a Y-type zeolite and having a counter ion at an acid site as a sodium ion. The Y-type zeolite has the general formula (1);
_{xNa 2 O · Al 2 O 3} · ySiO 2 · zH 2 O (1)
Can be expressed as In the general formula (1), the value of x, that is, the Na ₂ O / Al ₂ O ₃ molar ratio is 0.5 to 1.0, preferably 0.6 to 0.9. If the value of x is less than 0.5, the moisture adsorption capacity is low, so that moisture in the air with low absolute humidity cannot be sufficiently removed, and if it exceeds 1.0, it is difficult to dehumidify. Therefore, the amount of heat energy necessary for desorbing the moisture adsorbed by the Y-type zeolite (hereinafter referred to as the amount of dehumidification energy) increases. Moreover, the value of y, that is, the SiO ₂ / Al ₂ O ₃ molar ratio is 4.0 to 6.0, preferably 4.0 to 5.5. When the value of y is less than 4.0, it is difficult to dehumidify, so the amount of dehumidification energy increases. When the value of y exceeds 6.0, the moisture adsorption capacity is low. Cannot be removed sufficiently.

  The fact that the zeolite is a Y-type zeolite can be confirmed by a diffraction pattern obtained by performing X-ray diffraction analysis.

The average particle size of the Y-type zeolite is 3 μm or less, preferably 0.8 to 2.0 μm. When the average particle diameter exceeds 3 μm, it is difficult to dehumidify, so the amount of dehumidifying energy for regenerating the Y-type zeolite increases. Even if the sodium Y-type zeolite has the same Na ₂ O / Al ₂ O ₃ molar ratio and SiO ₂ / Al ₂ O ₃ molar ratio, the amount of dehumidifying energy varies greatly depending on the difference in average particle diameter. For example, when the average particle size is 3 μm, the amount of dehumidification energy is approximately 20% lower than that when the average particle size is 5 μm.

In the present invention, the amount of dehumidifying energy refers to the amount of heat energy required to dehumidify 1 g of water adsorbed by the Y-type zeolite from the Y-type zeolite. And this dehumidification energy amount is calculated | required with the following method. (I) First, the Y-type zeolite is dried in a dryer at 500 ° C. for 2 hours. Thereafter, the zeolite is removed from the dryer, and the zeolite is cooled to 25 ° C. in a desiccator containing a desiccant. Then, the zeolite is put into a weighing bottle, the weighing bottle is sealed, and weighed by a balance, and the weight of the zeolite when dried (dry weight X (g)) is measured. (Ii) The zeolite after drying is left for 48 hours in a desiccator controlled at 25 ° C. and 90% RH. Then, the zeolite is put into a weighing bottle, the weighing bottle is sealed, and weighed by a balance, and the weight of the zeolite when it absorbs moisture (moisture absorption weight Y (g)) is measured. (Iii) Then, the value of the dry weight X is subtracted from the value of the hygroscopic weight Y to obtain the saturated adsorbed water content of the zeolite. (Iv) Next, 20.0 mg of the zeolite after moisture absorption is weighed, and using a differential scanning calorimeter (DSC), the amount of heat energy (Z ( J)) is measured. (V) The amount of dehumidification energy (J / g) is calculated by the following equation (2).
Dehumidification energy amount = (Z × X) / {0.02 × (Y−X)} (2)

  Since the Y-type zeolite is excellent in repeated wet and dry durability, it has a long life as a dehumidifying agent, and therefore the running cost can be reduced. In addition, the wet and dry repeated durability of the Y-type zeolite can be grasped by measuring the moisture absorption rate of the Y-type zeolite before and after the wet and dry repeated test, and the moisture absorption rate before and after the wet and dry repeated test and the moisture absorbed rate after the test. When there is no change, it is judged that the wet and dry repeated durability is good. In the present invention, the wet and dry repeated test means that the Y-type zeolite is heated at 800 ° C. for 10 minutes, then cooled to 25 ° C. in a desiccator containing a desiccant, and then 25 ° C. and 50% RH. This is a test in which the operation of leaving in a desiccator for 10 minutes is repeated 100 times.

The Y-type zeolite is prepared by, for example, a sodium Y-type zeolite having a Na ₂ O / Al ₂ O ₃ molar ratio and a SiO ₂ / Al ₂ O ₃ molar ratio within the above ranges by a conventional method such as dry grinding or wet grinding. It is obtained by pulverization and classification by a conventional method such as combing, if necessary.

The Y-type zeolite according to the present invention has the Na ₂ O / Al ₂ O ₃ molar ratio, the SiO ₂ / Al ₂ O ₃ molar ratio, and the average particle diameter in the above ranges, so that moisture in the air with low absolute humidity is present. Has a moisture absorption performance necessary for adsorbing water and has a small amount of dehumidifying energy during regeneration. Therefore, the Y-type zeolite has a good balance between moisture absorption performance and dehumidification performance.

  Thus, by setting the specific physical properties of the sodium Y-type zeolite excellent in repeated wet and dry durability to a specific range, it exhibits excellent dehumidification performance and dehumidification performance even in the air with low absolute humidity, In addition, it is possible to provide a dehumidifying agent having excellent dry and wet repeated durability.

  The dehumidifying agent of the present invention is used as a dehumidifying agent for a honeycomb rotor configured by supporting a dehumidifying agent on a porous honeycomb structure having a large number of small pores therein. The honeycomb rotor is divided into a dehumidification zone for dehumidifying the air to be treated, a regeneration zone for regenerating the dehumidifying agent, and a cooling zone for cooling the honeycomb rotor heated in the regeneration zone, and the honeycomb rotor rotates. As a result, the dehumidifying agent sequentially moves through the dehumidifying zone, the regeneration zone, and the cooling zone.

The dehumidifying member of the present invention has a SiO ₂ / Al ₂ O ₃ molar ratio of 4.0 to 6.0, a Na ₂ O / Al ₂ O ₃ molar ratio of 0.5 to 1.0, and an average particle diameter of 3 μm. The following Y-type zeolite is supported on a carrier.

  The carrier is not particularly limited as long as it is a porous body capable of supporting the Y-type zeolite, and is preferably a honeycomb structure carrier, and particularly preferably described in JP-A-59-10345. It is comprised by the high porosity inorganic fiber paper. The inorganic fiber papermaking is preferably made of inorganic fibers such as alumina fibers, silica alumina fibers or glass fibers and having a high porosity of 70 to 95%.

  The method for supporting the Y-type zeolite is not particularly limited, and can be performed by a conventional method. For example, a suspension is prepared by suspending the Y-type zeolite in water together with an inorganic binder such as silica sol, alumina sol or titania sol, and the carrier is immersed in the suspension, or the suspension is suspended in the carrier. The Y-type zeolite is sufficiently absorbed by the carrier by coating, and the excess suspension is removed, and then dried and fixed. At this time, the amount of the inorganic binder to be used is the minimum necessary for fixing to the surface of the carrier. The Y-type zeolite is formed by covering the surface of the Y-type zeolite with the cured product of the inorganic binder. This is preferable in that the decrease in the hygroscopic performance can be reduced.

  EXAMPLES Next, although an Example is given and this invention is demonstrated more concretely, this is only an illustration and does not restrict | limit this invention.

(Production of sodium Y-type zeolite)
SiO ₂ content is 63 wt%, Al ₂ O ₃ content is 24 wt%, Na ₂ O content is 13 wt% (SiO ₂ / Al ₂ O ₃ molar ratio is 4.46, Na ₂ O / Al ₂ Sodium Y-type zeolite A having an O ₃ molar ratio of 0.89) was pulverized and classified to obtain sodium Y-type zeolite B having an average particle size of 1.2 μm.

(Hygroscopic test)
A hygroscopic test was conducted in accordance with JIS Z 0701-1977 except that the sample was not crushed in advance and subjected to a sieving operation using a nominal size of 840 or less according to JIS Z 8801. The results are shown in Table 1. The temperature in the desiccator during the hygroscopic test was 26 ° C.

(Measurement of dehumidification energy)
First, sodium Y-type zeolite B was dried in a dryer at 500 ° C. for 2 hours. After drying, the zeolite was removed from the dryer and cooled to 25 ° C. in a desiccator containing a desiccant. The zeolite was put into a weighing bottle, the weighing bottle was sealed, weighed with a balance, and the dry weight (X) of the zeolite was measured. As a result, it was 0.200 g. Next, the dried zeolite was allowed to stand for 48 hours in a desiccator controlled at 25 ° C. and 90% RH. The zeolite was put into a weighing bottle, the weighing bottle was sealed, weighed with a balance, and the moisture absorption weight (Y) of the zeolite was measured to be 0.261 g. Next, 20.0 mg of the zeolite after moisture absorption was weighed and heated using a differential scanning calorimeter (DSC) (DSC8230D, manufactured by Rigaku Corporation) from 30 ° C. under a temperature rising condition of 10 ° C./min. The amount of heat energy (Z) required for moisture to be dehumidified from the zeolite after moisture absorption was measured to be 19.52 J. And when the amount of dehumidification energy was calculated by the following formula (2), it was 3.2 × 10 ³ J / g.
Dehumidification energy amount (J / g) = (Z × X) / {0.02 × (Y−X)} (2)

(Dry and wet repeated test)
10 g of sodium Y-type zeolite B was heated at 800 ° C. for 10 minutes in an automatic elevator, cooled to 25 ° C. in a desiccator containing a desiccant, and then 10 minutes in a desiccator at 25 ° C. and 50% RH. The operation of leaving it to stand was repeated 100 times, and the dry and wet test was repeated.

(Evaluation of repeated wet and dry durability)
Next, the moisture absorption rate of the sodium Y-type zeolite B before and after the wet and dry repeat test was measured, and the wet and dry repeated durability was evaluated from the amount of change in the moisture absorption rate before and after the dry and wet repeat test. The moisture absorption rate is measured by heating 1 g of sodium Y-type zeolite B in a desiccator containing a desiccant after heating at 200 ° C. for 1 hour, and installing it in a room controlled at 25 ° C. and 50% RH. Place it on the balance. The weight is measured once every 5 seconds, and the weight measurement is performed for 10 minutes. Next, for each weight measurement made at 5-second intervals, calculate the amount of weight increase from the previous weight measurement and divide by the measurement interval (5 seconds) to change the weight per unit time (mg / second) Is calculated. The weight change is calculated for every weight measurement performed for 10 minutes, and the average value (mg / second) is obtained. Then, the average value is divided by the weight of 1 g of sodium Y-type zeolite B to obtain a moisture absorption rate per 1 g (mg / second). The moisture absorption rate of sodium Y-type zeolite B was 0.27 mg / second per gram in air at 25 ° C. and 50% RH before the test, and remained unchanged at 0.27 mg / second after the test.

(Comparative Example 1)
(Hygroscopic test)
The same procedure as in Example 1 was performed except that A type silica gel (Galeon silica gel A, manufactured by Mizusawa Chemical Co., Ltd.) was used instead of sodium Y type zeolite B. The results are shown in Table 1.

(Comparative Example 2)
(Hygroscopic test)
The same procedure as in Example 1 was performed except that B-type silica gel (Galeon Silica Gel B, manufactured by Mizusawa Chemical Industry Co., Ltd.) was used instead of sodium Y-type zeolite B. The results are shown in Table 1.

  Thus, the sodium Y-type zeolite B of Example 1 had a constant hygroscopicity regardless of the absolute humidity, and showed a high hygroscopic property even in air with a low absolute humidity. On the other hand, the A-type silica gel of Comparative Example 1 and the B-type silica gel of Comparative Example 2 have lower hygroscopicity as the absolute humidity is lower, and the hygroscopicity is very low in the air having a lower absolute humidity.

(Comparative Example 3)
(Production of sodium Y-type zeolite)
Sodium Y-type zeolite A used in Example 1 was pulverized and classified to obtain sodium Y-type zeolite C having an average particle size of 5.1 μm.

(Measurement of dehumidification energy, repeated wet and dry test, repeated wet and dry durability)
The same procedure as in Example 1 was performed except that sodium Y-type zeolite C was used instead of sodium Y-type zeolite B. As a result, the dehumidification energy amount was 4.0 × 10 ³ J / g. Further, the moisture absorption rate before the wet and dry repeated test was 0.26 mg / second per 1 g in air at 25 ° C. and 50% RH, and remained unchanged at 0.26 mg / second after the test.

(Comparative Example 4)
(Production of sodium Y-type zeolite)
SiO ₂ content is 76.3% by weight, Al ₂ O ₃ content is 16.2% by weight, Na ₂ O content is 7.3% by weight (SiO ₂ / Al ₂ O ₃ molar ratio is 5.1, Sodium Y-type zeolite D having a Na ₂ O / Al ₂ O ₃ molar ratio of 0.76) was pulverized and classified to obtain sodium Y-type zeolite E having an average particle size of 4.5 μm.

(Measurement of dehumidification energy, repeated wet and dry test, repeated wet and dry durability)
The same procedure as in Example 1 was performed except that sodium Y-type zeolite E was used instead of sodium Y-type zeolite B. As a result, the dehumidification energy amount was 3.8 × 10 ³ J / g. Further, the moisture absorption rate before the wet and dry repeated test was 0.26 mg / second per 1 g in air at 25 ° C. and 50% RH, and remained unchanged at 0.26 mg / second after the test.

(Comparative Example 5)
(Manufacture of potassium Y-type zeolite)
Sodium Y-type zeolite A used in Example 1 was immersed in a 0.9 mol / L potassium chloride aqueous solution at 80 ° C. for 12 hours. The Y-type zeolite was filtered off and washed with water, and then dried at 200 ° C. for 2 hours to obtain a Y-type zeolite ion-exchanged with potassium ions (hereinafter referred to as potassium Y-type zeolite F). The composition of the obtained potassium Y-type zeolite F has a SiO ₂ content of 60.0% by weight, an Al ₂ O ₃ content of 22.9% by weight, a K ₂ O content of 13.7% by weight, Na ₂ The O content was 3.4% by weight (SiO ₂ / Al ₂ O ₃ molar ratio was 4.5 and Na ₂ O / Al ₂ O ₃ molar ratio was 0.12).

(Measurement of dehumidification energy, repeated wet and dry test, repeated wet and dry durability)
The same procedure as in Example 1 was performed except that potassium Y-type zeolite F was used instead of sodium Y-type zeolite B. As a result, the dehumidification energy amount was 4.2 × 10 ³ J / g. Further, the moisture absorption rate before the wet and dry repeated test was 0.26 mg / second per 1 g in air at 25 ° C. and 50% RH, but was 0.24 mg / second after the test.

(Comparative Example 6)
(Manufacture of lanthanum Y-type zeolite)
Sodium Y-type zeolite A used in Example 1 was immersed in a 0.3 mol / L lanthanum chloride (LaCl ₃ ) aqueous solution at 80 ° C. for 12 hours. The Y-type zeolite was filtered off and washed with water, followed by drying at 200 ° C. for 2 hours to obtain a Y-type zeolite ion-exchanged with lanthanum ions (hereinafter referred to as lanthanum Y-type zeolite G). The composition of the obtained lanthanum Y-type zeolite G has a SiO ₂ content of 60.6% by weight, an Al ₂ O ₃ content of 20.8% by weight, a La ₂ O ₃ content of 14.7% by weight, Na _{The 2} O content was 3.7% by weight (SiO ₂ / Al ₂ O ₃ molar ratio was 5.0 and Na ₂ O / Al ₂ O ₃ molar ratio was 0.3).

(Measurement of dehumidification energy, repeated wet and dry test, repeated wet and dry durability)
The same procedure as in Example 1 was carried out except that the lanthanum Y type zeolite G was used instead of the sodium Y type zeolite B. As a result, the dehumidification energy amount was 3.4 × 10 ³ J / g. Further, the moisture absorption rate before the wet and dry repeated test was 0.24 mg / second per 1 g in air at 25 ° C. and 50% RH, but was 0.21 mg / second after the test.

(Manufacture of dehumidifying members)
A honeycomb structure carrier made of silica alumina fiber paper (thickness 0.2 mm, porosity 90%) and having cells having a width of 3.0 mm and a height of 1.6 mm (manufactured by NICHIAS Corporation, trade name: hanicle) It was cut into a cylindrical shape with a diameter of 270 mm and a thickness of 17 mm to obtain a carrier.
Next, 90 parts by weight of the sodium Y-type zeolite B obtained in Example 1, 30 parts by weight of silica sol (“trade name: Snowtex” (solid content 30% by weight, manufactured by Nissan Chemical Co., Ltd.)), and 130 parts by weight of water Were mixed to prepare a slurry. After the above honeycomb structure carrier was immersed in the obtained slurry, excess slurry was removed and dried to obtain a dehumidifying member H.

(Dry-wet repeat test, dry-wet repeat durability evaluation)
When the dehumidifying member H was used in place of 10 g of sodium Y zeolite B, the moisture absorption rate was 1 g of sodium Y zeolite B supported on the dehumidifying member. The hit was 0.27 mg / sec before the test and 0.27 mg / sec after the test.

(Dehumidification durability test)
A dehumidifying member H manufactured by the same method as described above is attached as a dehumidifying rotor of a dehumidifying device (F-Y100Z3, manufactured by Matsushita Ecosystems), and the dehumidifying device is controlled at 25 ° C. and 50% RH in a constant temperature and humidity chamber. And was dehumidified for 100 hours under “automatic” operating conditions. Then, the dehumidifying amount for 1 hour (between the first hour and the second hour) after 1 hour from the start of the test and the dehumidifying amount for 1 hour (from the 99th hour to the 100th hour) after 99 hours are measured, and the dehumidifying member The dehumidification durability of H was determined. The results are shown in Table 2. The amount of dehumidification is obtained by placing a dehumidifier on the electronic balance, operating under "automatic" operating conditions, recording the weight increase every minute, and measuring the total weight increase for one hour. It was. Further, the dehumidification rate is a value obtained by the following equation (3), assuming that the dehumidification amount after 1 hour is Pg / hour and the dehumidification amount after 100 hours is Qg / hour.
Reduction rate of dehumidification amount (%) = {(PQ) / P} × 100

(Comparative Example 7)
(Manufacture of dehumidifying members)
Dehumidification is performed in the same manner as in Example 2 except that 90 parts by weight of the sodium Y-type zeolite B obtained in Example 1 is replaced by 90 parts by weight of the lanthanum Y-type zeolite G obtained in Comparative Example 6. Member J was obtained.

(Dehumidification durability test)
The same procedure as in Example 2 was performed except that the dehumidifying member J was used instead of the dehumidifying member H. The results are shown in Table 2.

  As described above, the dehumidifying member H of Example 2 was excellent in durability even when the dehumidification endurance test for 100 hours was performed and the decrease in dehumidifying performance was extremely low.

Claims (3)

The following general formula (1):
_{xNa 2 O · Al 2 O 3} · ySiO 2 · zH 2 O (1)
Y having a SiO ₂ / Al ₂ O ₃ molar ratio of 4.0 to 6.0, a Na ₂ O / Al ₂ O ₃ molar ratio of 0.5 to 1.0, and an average particle size of 3 μm or less. Dehumidifier characterized by being a type zeolite. The following general formula (1):
_{xNa 2 O · Al 2 O 3} · ySiO 2 · zH 2 O (1)
Y having a SiO ₂ / Al ₂ O ₃ molar ratio of 4.0 to 6.0, a Na ₂ O / Al ₂ O ₃ molar ratio of 0.5 to 1.0, and an average particle size of 3 μm or less. A dehumidifying member characterized in that a zeolite is supported on a carrier.   The dehumidifying member according to claim 2, wherein the carrier is a honeycomb structure carrier.