JP2008161743A - Low temperature liquefied voc recovery method for performing removal of moisture and recovery of cold using adsorbent - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a VOC recovery method due to the low temperature condensation of VOC succeeding to the removal of moisture using the adsorbent. <P>SOLUTION: Air containing VOC and moisture is pressurized to be introduced into a moisture selectively adsorbent adsorbing column and brought into contact with the adsorbent to adsorb moisture by the adsorbent to remove moisture. Thereafter, VOC is recovered by liquefying, the cold is recovered from dried and low temperature air after recovering VOC, and then the moisture selectively adsorbent adsorbing column having adsorbed moisture is evacuated using dry air as a countercurrent purge gas and moisture is separated from the adsorbing column to perform the adsorptive recovery of moisture and the heat accumulation recovery of evaporation heat. The moisture selective adsorbent is at least one kind of an adsorbent selected from the group consisting of K-A, Na-A, Na-K-A and Ca-A. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a low-temperature liquefied VOC recovery method for removing moisture using an adsorbent and recovering cold heat.

  The most frequently used method for treating exhaust gas containing VOC is to supply VOC contained in the exhaust gas to an adsorption tower packed with high silica zeolite to adsorb and remove VOC, and to adsorb VOC. This is TSA-VOC + catalytic combustion in which high temperature hot air is supplied to the adsorption tower to desorb VOC at high temperature, and the desorbed VOC is oxidized and decomposed by catalytic combustion.

Also expected to be widely used in the future is a life-extinguishing discharge on the surface of a ferroelectric (barium titanate, etc.) packed by the US Environmental Protection Agency (EPA), which contains VOC-containing gas. There is a packed tower plasma treatment that oxidizes and decomposes by supplying (Paked Bed Plasma). Although these methods show a certain level of performance for VOC processing, TSA-VOC + catalytic combustion has the limitations of cost reduction due to the complexity of the equipment and the complexity of operation. In packed tower plasma processing, the target VOC and VOC are removed. There is a concern that the rate will be limited and future VOC emission regulations will not be met.

It may be possible to add ozone to the VOC-containing gas and oxidatively decompose it by homogeneous gas phase reaction of VOC, but the ozone oxidation reaction to low concentration VOC is slow, the treatment of unreacted ozone is complicated, and it is used as an oxidant Since the production cost of ozone is high, it has not been put into practical use. In order to improve the reaction efficiency of the ozone oxidation reaction, VOC is adsorbed on high silica zeolite and removed, then ozone is added to the high silica zeolite adsorbed with VOC and the co-adsorption of VOC and ozone in the zeolite is performed. It has been proposed to improve efficiency. Although the efficiency of the ozone reaction can be improved by this method, the cost of manufacturing ozone is still unsolved.

  In the prior art described above, a method for recovering the VOC without degrading it with high efficiency has not been put into practical use. In particular, using cold storage air as a method for recovering cold energy, using a heat storage heat exchanger, using VOC recovery as a method for using the moisture adsorbent, continuous cold energy recovery using dry air after recovering cold energy, moisture The use of removal methods is not known.

  The present inventors pressurize air containing a volatile organic compound (hereinafter referred to as VOC) and moisture and introduce it into a moisture-selective adsorbent adsorption tower in one of at least two tower-type adsorption towers. The water is adsorbed to the adsorbent and separated from the VOC, and then introduced into the heat storage material packed tower cooled to a low temperature, brought into contact with the heat storage material, cooled, and cooled to the coldest temperature. The VOC is liquefied and recovered by cooling in a vessel, and the low-temperature, low-VOC, and low moisture concentration air flowing through is reduced in pressure, introduced into another heat storage material packed tower and brought into contact with the heat storage material to recover the cold heat and rise. Warm, depressurize the air, introduce it into another moisture-selective adsorbent adsorption tower, bring it into contact with the adsorbent, desorb the moisture from the adsorbent, regenerate the moisture adsorbent, and before the moisture breaks through the tower VOC recovery under low-temperature liquefaction conditions by switching water and removing water and collecting cold heat Was found that the establishment of the law.

Thus, according to the present invention, the following inventions 1 to 6 are provided:
1. In at least one of the two-column type adsorption towers, air containing volatile organic compounds (hereinafter VOC) and moisture is pressurized and introduced into the moisture-selective adsorbent adsorption tower to be brought into contact with the adsorbent and moisture. Is adsorbed by the adsorbent and separated from the VOC, then introduced into the heat storage material packed tower cooled to a low temperature, brought into contact with the heat storage material, cooled, and cooled by a cooler to reach the coldest temperature and VOC. Liquefying and recovering, introducing low temperature, low VOC, low moisture concentration air flowing into another heat storage material packed tower and bringing it into contact with the heat storage material, recovering the cold heat, raising the temperature, depressurizing the air It is introduced into another moisture-selective adsorbent adsorption tower and brought into contact with the adsorbent to desorb the moisture from the adsorbent to regenerate the moisture adsorbent, and before the moisture breaks through, the tower is switched to remove moisture and cool A low-temperature liquefied VOC recovery method for performing recovery. (Claims 1 and 2)

2. The VOC according to claim 1, wherein the moisture-selective adsorbent is at least one selected from the group consisting of KA, Na-A, Na-KA, and Ca-A. Low temperature liquefied VOC recovery method. (Claim 2)

3. One or more kinds of moisture-selective adsorbents selected from the group consisting of KA, Na-A, Na-KA, and Ca-A whose surfaces are in a liquid phase and silica-coated with a hydrolysis product of an organosilicon compound The VOC according to claim 1, wherein the low-temperature liquefied VOC is recovered after removing water from the water-containing air.
(Claim 3)

4). One or more kinds of moisture-selective adsorbents selected from the group consisting of KA, Na-A, Na-KA, and Ca-A whose surfaces are in the gas phase and silica-coated with hydrolysis products of organosilicon compounds The VOC according to claim 1, wherein the low-temperature liquefied VOC is recovered after removing water from the water-containing air.
(Claim 4)

5. A low-temperature liquefied VOC recovery method for performing water removal and cold recovery according to any one of claims 1 to 5, wherein the moisture-selective adsorbent is formed in a honeycomb.
(Claim 5)

6). Low-temperature liquefied VOC that removes water and recovers cold heat with pressure ratio Pa / Pd of 1.1 or more as tower pressure Pa (kPa) in the adsorption process and tower pressure Pd (kPa) in the regeneration process Collection method.
(Claim 6)

In this method, since the separation of VOC and moisture is performed in an adsorption tower filled with a moisture adsorbent that hardly adsorbs VOC near atmospheric pressure, it is possible to easily prepare ultra-dry VOC-containing dry air. Then, it is cooled in a packed tower filled with a heat storage material, and supplemented with a freezer with insufficient refrigeration, so that the VOC in the VOC-containing air is liquefied and recovered without being highly concentrated at a low temperature below room temperature. You can Therefore, the recovery process is safe because it is performed below the explosion limit, and VOC is recovered without deterioration. In addition, low-temperature and ultra-dry air after VOC recovery is recovered in the packed tower filled with the heat storage material, and is further used for moisture removal regeneration of the moisture adsorption tower, so that the energy of VOC recovery can be greatly reduced. . By adopting this method, it is possible to provide an energy-saving VOC recovery device that does not deteriorate the recovered solvent and adsorbent by safe operation below the explosion limit.

The moisture selective adsorbent used in the present invention is at least one selected from the group consisting of KA, Na-A, Na-KA, and Ca-A. Here, Na-K-A is obtained by reducing a window diameter by exchanging a part of Na of Na-A-type zeolite with K and performing heat treatment, and this preparation method is Oxygen Selectivity on Partially K Exchanged Na. -A Type Zeolite at Low Temperature, IZUMI J, SUZUKI M, ADSORPTION, VOL. 7 PAGE. 27-39, (2001).
The adsorbent is judged to have a high moisture / VOC separation factor in the VOC-water binary system.

  The surface is at least one selected from the group consisting of KA, Na-A, Na-KA, and Ca-A that is silica-coated with a hydrolysis product of an organosilicon compound in a liquid phase or a gas phase. preferable. Moisture selectivity is enhanced by silica-coating the surface of the adsorbent crystal in the gas phase or liquid phase with the hydrolysis product of the organosilicon compound.

In the adsorbent having a silica coat on the crystal surface used in the present invention, a zeolite powder is suspended in a slurry in a solvent such as methyl alcohol, and a template such as tetraethoxyorthosilicate (TEOS) is added to the crystal surface at the required thickness. When an amount corresponding to the above is added and moisture is added to this at an H ₂ O / TEOS ratio of about 5 to 20, silica is precipitated.

  After coating is completed, silica sol is added to prepare a slurry of zeolite: silica sol: deionized water = 5 to 30: 1 to 10: 100, and the slurry is immersed and supported on the honeycomb substrate, and the temperature is about 90 to 150. The surface water was removed at about 0.5 to 3 hours at a temperature of about 30 to 80 ° C./h and the temperature was maintained at about 250 to 450 ° C. for about 0.5 to 3 hours to complete the dehydration of silicic acid. Thus, the Si—O—Si network on the zeolite crystal surface is completed and the activation by dehydration is completed. Under this coating condition, a silica thin film of 0.05 to 0.1 μm is formed on the crystal surface.

Similarly, when ammonia vapor containing TEOS (tetra-ethyl-ortho-silicate) or TMOS (tetra-methyl-ortho-silicate) is adsorbed on the A-type zeolite powder, the surface of the A-type zeolite crystal is hydrolyzed by TEOS and TMOS. In addition, a Si-O-Si network is formed to produce a silica thin film.

Silica-coated KA, Na-A, Na-KA, and Ca-A zeolite may be used in combination of two or more thereof.

If the adsorbent having a silica coat on the crystal surface used in the present invention is a honeycomb-formed adsorbent, it is desirable because the pressure loss when passing through the adsorbent adsorption tower is reduced. As a method for preparing the honeycomb, the zeolite is supported by dipping in a mixed slurry of the zeolite and an inorganic binder such as silica sol on an aluminosilicate substrate and drying it. When the soaking and drying are repeated several times, a predetermined loading amount is reached. (Bulk density of 0.3 or more, zeolite loading of 0.1 g / ml or more) When this is calcined at 350 ° C. or more for 1 hour, fixation and activation of the zeolite to the base material are achieved.
Another method is to prepare a paper containing zeolite with aluminosilicate fiber, the zeolite, inorganic binder, and cellulose (making paper), forming a part of it into a corrugated shape using a corrugating machine, and laminating flat plates and corrugated plates alternately. Then, the honeycomb is formed. When this is calcined at 350 ° C. or higher for 1 hour, fixation and activation of the zeolite to the base material are achieved.

First step (A tower-adsorption process, B tower-countercurrent purge process)
In FIG. 1, an air containing VOC and water is supplied from a flow path 1 and a blower 2 to a water adsorption tower 4a filled with a moisture adsorbent 5 having a high moisture / VOC selectivity through a valve 3a. When supplied at ˜150 kPA, only moisture is selectively adsorbed and room temperature and ultra-dry air containing VOC flows from the rear of the tower, and the heat storage material is filled with the heat storage material 9 through the pressure reducing valve 6a and the valve 7a. It is supplied to the material packed tower 8a. At this time, the tower 8a is cooled by the cold heat collected in the previous regeneration step, comes into contact with the VOC-containing, room temperature dry air, the heat storage material 9 is heated, and the dry air is cooled. The low-temperature, VOC-containing dry air flowing from the flow path 10 is cooled to the coldest temperature by the chiller unit 11, and VOC is liquefied and recovered from the flow path 12. Low-temperature and ultra-dry air containing unrecovered VOC is supplied from the flow path 13 to the heat storage material packed tower 8b filled with the heat storage material 9, the heat storage material 9 is cooled, and the dry air is heated. The dried air whose temperature has been raised is supplied counter-currently to the moisture adsorption tower 4b filled with the moisture adsorbent 5 through the valve 7b and the pressure reducing valve 6b. Here, since the adsorption tower 4b is exhausted by the vacuum pump 14 through the valve 9b, the moisture adsorbed at a low pressure of about 50 to 80 kPa is desorbed and regenerated. Here, the heat storage material is 0.5 ~ 10KMF, metal absorption of aluminum tower.

Second step (A tower-adsorption process, B tower-pressurization process)
When regeneration of the moisture adsorbent 5 in the moisture adsorption tower 4b is completed and the valve 9b is closed just before the moisture adsorption zone of the moisture adsorption tower 4a reaches the rear of the tower, the pressure in the heat storage material packed tower 8b and the moisture adsorption tower 4b is increased. Is increased to a pressure substantially equal to the adsorption pressure, and the second step is completed.

  Here, the same operation as the first and second steps is performed in the third to fourth steps by changing the A tower and the B tower. Table 1 shows the sequence of the low-temperature liquefied VOC recovery method for performing moisture adsorption removal and regenerative cold recovery by this apparatus.

以下実施例により本発明をさらに具体的に説明する。

Hereinafter, the present invention will be described more specifically with reference to examples.

First step (A tower-adsorption process, B tower-countercurrent purge process)
In FIG. 1, a moisture adsorption tower filled with moisture adsorbent 5 having high moisture / toluene selectivity through passage 1, blower 2 and valve 3 a through air containing 5,000 ppm of toluene and moisture of 2.5 vol%. When 4a is supplied at an adsorption pressure of about 110 to 150 kPA, only water is selectively adsorbed and contains toluene at room temperature (25 ° C.), in an extremely dry state (moisture concentration of 10 ppm or less, DP-60 ° C. or less) ) Flows from behind the tower and is supplied to the heat storage material packed tower 8a filled with the heat storage material 9 through the pressure reducing valve 6a and the valve 7a. The moisture adsorbent is a honeycomb (bulk density 0.4 g / cm3, pitch between plates 2 mm, plate thickness 0.2 mm) carrying the candidate adsorbent powder. At this time, the tower 8a is cooled to −50 ° C. by the cold heat recovered in the previous regeneration step, comes into contact with the dry air of 5,000 ppm of toluene and 25 ° C., and the heat storage material 9 is heated to 20 ° C. The dry air is then cooled to -50 ° C. The dry air containing −50 ° C. and 5,000 ppm of toluene flowing from the flow path 10 is cooled to −65 ° C., which is the coldest in the chiller unit, and liquefied and recovered from the flow path 12 at a recovery rate of about 90%. Ultra-dry air containing 500 ppm of unrecovered VOC and having a temperature of −65 ° C. and a moisture concentration of 10 ppm or less (DP-60 ° C. or less) is supplied from the flow path 13 to the heat storage material packed tower 8 b filled with the heat storage material 9 to store heat. The material 9 is cooled to −50 ° C., and the dry air is heated to 20 ° C. The dried air whose temperature has been raised is supplied counter-currently to the moisture adsorption tower 4b filled with the moisture adsorbent 5 through the valve 7b and the pressure reducing valve 6b. Here, since the adsorption tower 4b is exhausted by the vacuum pump 14 through the valve 9b, the moisture adsorbed at a low pressure of about 50 to 80 kPa is desorbed and regenerated.
The operation of regenerating the adsorbent by flowing dry air in countercurrent under reduced pressure is called countercurrent purge. The countercurrent purge rate K is defined as Pa (kPa) for the adsorption pressure and Pd (kPa) for the regeneration pressure.
K = Pa / Pd
Defined by According to the results of this experiment, it is difficult to keep the outlet moisture concentration at 10 ppm or less unless K is at least 1.1 or more.

Second step (A tower-adsorption process, B tower-pressurization process)
When regeneration of the moisture adsorbent 5 in the moisture adsorption tower 4b is completed and the valve 9b is closed just before the moisture adsorption zone of the moisture adsorption tower 4a reaches the rear of the tower, the pressure in the heat storage material packed tower 8b and the moisture adsorption tower 4b is increased. Is increased to 110 to 150 kPa, which is substantially equal to the adsorption pressure, and the second step is completed.

  Here, the same operation as the first and second steps is performed in the third to fourth steps by changing the A tower and the B tower.

Examples 1 to 13 and Comparative Examples 14 and 15: Preparation Examples and Performance Evaluation of Various Zeolite Type Water Adsorbents as Water Selective Adsorbents In order to confirm the effectiveness of the present invention, the water selective adsorbent honeycomb 5 of the packed tower 4a KA, Na-A, Na-KA, KA (10 nm), Na-A (10 nm), Na-KA (10 nm), KA (50 nm), Na-A ( 50 nm), Na-KA (50 nm), KA (100 nm), Na-A (100 nm), and Na-KA (100 nm).

Here, the values in parentheses in KA, Na-A, and Na-KA are the thin film thickness of the silica coat. Here, for thin film growth on zeolite crystals by silica coating of KA, Na-A, and Na-KA, zeolite powder is suspended in a slurry in methyl alcohol, and tetraethoxy orthosilicate (TEOS) is suspended in this. Is added to the crystal surface in an amount corresponding to the required thickness, and when water is added thereto at a H ₂ O / TEOS molar ratio of about 10, silica is precipitated. (This time, adjustment was made so that 10 to 20 nm of silica was deposited by one coating, and this time, adjustment was made to be 50 nm by 3 times and 100 nm by 5 times.)

  After finishing the coating, it is immersed in the honeycomb substrate and supported at a bulk specific gravity of about 0.4, and after removing surface moisture at 110 ° C. for 1 hour, the temperature is raised to 50 ° C./h to 350 ° C. For 1 hour to complete the dehydration of silicic acid to complete the Si—O—Si network on the zeolite crystal surface, and the activation by dehydration is completed.

The results of Examples 1 to 13 are shown in Table 2. (SAMPLE # 14 and 15 are comparative reference test results.)

  In both cases, the toluene recovery rate is 90% or more, and the dew point at the outlet of the moisture adsorption tower is below −60 ° C., indicating the effectiveness of the present invention. In particular, KA, Na-KA, Na-A, and these silica-coated products showed high moisture adsorption performance showing a molecular sieving effect on toluene. In particular, KA (10 nm) showed high moisture removal performance and high toluene recovery. This is presumably because the window diameter (the crystal gas passage) has a relatively high moisture adsorption rate and molecular sieve effect on toluene.

Example 14
Next, KA (10 nm) having the highest performance as an adsorbent was used as a honeycomb, and the relationship between the inlet flow rate, the toluene recovery rate, and the outlet moisture concentration at a cycle time of 5 minutes was examined. The results are shown in Table 3.

As the raw material flow rate increases, the toluene recovery rate increases to 99.5%, but the moisture concentration at the outlet of the moisture adsorption tower also increases. However, even at 7,500 m ³ N / h, the water concentration is only about 8 ppm, and high performance is maintained. When the flow rate is reduced to about 4,000 m ³ N / h, the toluene recovery rate is reduced to 97%, but the water concentration can be reduced to 2 ppm.

Example 15
Next, KA (10 nm) having the highest performance as an adsorbent was used as a honeycomb, and the relationship between the cycle time, toluene recovery rate, and moisture adsorption tower outlet moisture concentration was examined. The results are shown in Table 4.

  As the cycle time is shortened, the toluene recovery rate increases and the moisture concentration at the outlet of the moisture adsorption tower decreases. At a cycle time of 5 minutes, a toluene recovery rate of 99.6% and an outlet moisture concentration of about 6 ppm are maintained. Further, when the cycle time is reduced to about 1 minute, the performance is improved to a toluene recovery rate of 99.8% and an outlet moisture concentration of about 2 ppm. Therefore, it can be seen that the amount of adsorbent used can be reduced by shortening the cycle time.

Example 16
Next, KA (10 nm) having the highest performance as an adsorbent was used as a honeycomb, and the relationship between the adsorption pressure, the toluene recovery rate, and the moisture concentration at the moisture adsorption tower outlet was examined. The results are shown in Table 5.

  As the adsorption pressure increases, the toluene recovery rate increases and the moisture concentration at the moisture adsorption tower outlet decreases. At an adsorption pressure of 120 kPa, the toluene recovery rate increases to 99.6%, and the water concentration at the outlet of the water adsorption tower decreases to 3 ppm.

Example 16
Next, KA (10 nm) having the highest performance as an adsorbent was used as a honeycomb, and the relationship between the regeneration pressure, the toluene recovery rate, and the moisture concentration at the outlet of the moisture adsorption tower was examined. The results are shown in Table 6.

  As the regeneration pressure decreases, the toluene recovery rate increases and the moisture concentration at the outlet of the moisture adsorption tower decreases. At a regeneration pressure of 80 kPa, the toluene recovery rate increases to 99.6%, and the water concentration at the outlet of the water adsorption tower decreases to 6 ppm.

Example 16
Next, KA (10 nm) having the highest performance as an adsorbent was used as a honeycomb, and the relationship between the condensation temperature, the toluene recovery rate, and the moisture concentration at the outlet of the moisture adsorption tower was examined. The results are shown in Table 7.

As the condensation temperature decreases, the toluene recovery rate increases and reaches 99.6% at a condensation temperature of -60 ° C.

Example 18
Inlet gas flow rate is 5,000 m ³ N / h, gas composition is methyl ethyl ketone 5,000 ppm, moisture 2.5 vol%, balance gas air, cycle time 5 minutes, adsorption pressure 120 kPa, regeneration pressure 80 kPa, condensation temperature −65 ° C. Recovery was performed, and recovery performance with a methyl ethyl ketone recovery rate of 98% and a water concentration of 5 ppm was confirmed.

Example 19
Inlet gas flow rate 5,000 m ³ N / h, gas composition as isopropyl alcohol 25 vol%, moisture 2.5 vol%, balance gas nitrogen, cycle time 5 minutes, adsorption pressure 120 kPa, regeneration pressure 80 kPa, condensation temperature −65 ° C. The recovery performance of isopropyl alcohol recovery rate of 98% and water concentration of 5 ppm was confirmed. The water concentration in the recovered isopropyl alcohol was reduced to 0.01 w% or less, indicating that it was possible to produce anhydrous alcohol.

Example 20
In toluene recovery at an inlet gas flow rate of 5,000 m ³ N / h, gas composition of toluene 5000 ppm, moisture 2.5 vol%, balance gas air, cycle time 5 minutes, adsorption pressure 120 kPa, regeneration pressure 80 kPa, condensation temperature −65 ° C. In place of the heat storage type heat exchanger, a plate fin type heat exchanger is provided between the inlet and outlet of the chiller unit to perform heat exchange between the adsorption process outlet gas and the regeneration process inlet gas, and is similar to the heat storage type heat exchanger. The performance was confirmed. (Toluene recovery rate 99.6%, moisture concentration 6 ppm)

  VOC can be recovered from various exhaust gases including VOC gas and is not discharged to the outside. Further, the recovered VOC is hardly deteriorated, and the VOC can be recovered with low cost and high efficiency and can be completely reused.

1 shows a first embodiment of the present invention.

Explanation of symbols

10, 12, 13 Channel 2 Blowers 3a, 3b. 7a, 7b, 9a, 9b Automatic valve 4a, 4b Moisture adsorption tower 5 Moisture selective adsorbent 6a, 6b Pressure reducing valve 8a, 8b Heat storage material filling tower 9 Heat storage material 11 Chiller unit 14 Vacuum pump

Claims (7)

  In at least one of the two-column type adsorption towers, air containing volatile organic compounds (hereinafter VOC) and moisture is pressurized and introduced into the moisture-selective adsorbent adsorption tower to be brought into contact with the adsorbent and moisture. Is adsorbed on the adsorbent and separated from the VOC, and then cooled by a cooler to reach the coldest temperature, the VOC is liquefied and recovered, and the low VOC and low moisture concentration air flowing through is reduced in pressure, etc. Introduced into a moisture-selective adsorbent adsorption tower that has adsorbed moisture and brought into contact with the adsorbent to desorb moisture from the adsorbent to regenerate the moisture adsorbent, and switch the tower to remove moisture before moisture breaks through Low temperature liquefied VOC recovery method. In Claim 1, it introduce | transduces into a water | moisture-content type | mold adsorbent adsorption tower, makes it contact with an adsorbent, makes water adsorb | suck to an adsorbent, isolate | separates from VOC, and introduce | transduces into the heat storage material packed tower cooled to low temperature subsequently. Cooling by contacting with heat storage material, cooling with a cooler to reach the coldest temperature, liquefying and recovering VOC, and flowing low temperature, low VOC, low moisture concentration air to other heat storage material packed tower Introduce it into contact with the heat storage material, recover the cold heat, raise the temperature, reduce the air, introduce it into another moisture selective adsorbent adsorption tower and contact with the adsorbent to desorb the moisture from the adsorbent A low-temperature liquefied VOC recovery method in which the moisture adsorbent is regenerated and the tower is switched before moisture breaks through to remove moisture and recover cold.
  The VOC according to claim 1, wherein the moisture-selective adsorbent is at least one selected from the group consisting of KA, Na-A, Na-KA, and Ca-A. Low temperature liquefied VOC recovery method.   One or more kinds of moisture-selective adsorbents selected from the group consisting of KA, Na-A, Na-KA, and Ca-A whose surfaces are in a liquid phase and silica-coated with a hydrolysis product of an organosilicon compound The VOC according to claim 1, wherein the low-temperature liquefied VOC is recovered after removing water from the water-containing air.   One or more kinds of moisture-selective adsorbents selected from the group consisting of KA, Na-A, Na-KA, and Ca-A whose surfaces are in the gas phase and silica-coated with hydrolysis products of organosilicon compounds The VOC according to claim 1, wherein the low-temperature liquefied VOC is recovered after removing water from the water-containing air.   A low-temperature liquefied VOC recovery method for performing water removal and cold recovery according to any one of claims 1 to 5, wherein the moisture-selective adsorbent is formed in a honeycomb.   Low-temperature liquefied VOC that removes water and recovers cold heat with pressure ratio Pa / Pd of 1.1 or more as tower pressure Pa (kPa) in the adsorption process and tower pressure Pd (kPa) in the regeneration process Collection method.

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