JP2645251C - - Google Patents

Description

Description: TECHNICAL FIELD The present invention selectively removes an inert gas such as an active gas contained in air, particularly a harmful gas such as an organic solvent vapor or a malodorous substance, to obtain a clean inert gas such as air. It relates to a gas adsorption element. BACKGROUND ART Since zeolite is mainly composed of aluminosilicate and selectively adsorbs gas molecules such as water vapor and organic solvent vapor according to the molecular diameter due to the difference in the diameter of pores generated by releasing water of crystallization. Used as an adsorbent as a molecular sieve. As an element for a dehumidifier, for example, Japanese Patent Application Laid-Open No. 54-19548 discloses a sheet made of asbestos paper, glass fiber paper, or the like, to which a molecular sieve (4A, 13X, etc.) is adhered, corrugated, and laminated. A rotary regeneration type dehumidifier comprising a cylindrical honeycomb structure has been proposed. Japanese Patent Application Laid-Open No. 63-240921 discloses a binder for powders of synthetic zeolites such as A type, X type and Y type or mordenite and other natural zeolites. , Extrusion molding,
A dehumidifying material having a honeycomb structure by press molding or the like has been proposed. On the other hand, as a rotary adsorption element for adsorbing and separating an organic solvent vapor, an odorous gas and the like from the air, for example, Japanese Patent Application Laid-Open No. 53-50068 proposes an element having a honeycomb structure made of paper containing fibrous activated carbon. The above-mentioned zeolite is capable of selectively adsorbing gas molecules according to its molecular diameter, as is called "moleculase". Since water vapor always coexists in the air, water vapor is surely adsorbed together with organic solvent vapor, odorous gas and the like. The diameter of the water molecule is 2.8 mm,
On the other hand, the molecular diameter of organic solvents or odorous gases is, for example, 6.7Å for benzene and 6.1Å for cyclohexane, which are all larger than the diameter of water molecules.Zeolite can adsorb and separate only water, but it is in the presence of water vapor. It is not possible to adsorb and separate only organic solvent vapor or odorous gas, but rather adsorb water vapor preferentially, and the adsorption of organic solvent vapor or odorous gas is hindered by the preferentially adsorbed water molecules. When the absolute humidity of the processing air is high, it is not possible to efficiently adsorb and separate organic solvent vapor or odorous substances. Activated carbon is a hydrophobic adsorbent and preferentially adsorbs non-polar molecules such as hydrocarbons, but there is a danger of ignition if hot air at a temperature of 130 ° C. or higher is used for regeneration because of its flammability. Further, depending on the type of the adsorbed solvent, the heat generated by the adsorption is large and the adsorbing element may be ignited, which makes it extremely difficult to use. Further, when the device is used for a certain period and its activity is reduced due to attachment of oil or the like, if it is to be activated, a high temperature treatment of about 300 ° C. must be performed. However, hot air cannot be used for this high temperature treatment. There were defects such as the need to activate using superheated steam. DISCLOSURE OF THE INVENTION The present invention uses a zeolite having a high silica component content to impart hydrophobicity as an adsorbent, to a block-shaped or honeycomb-shaped laminate having a large number of small through holes on both end surfaces. An inert gas containing an organic solvent vapor and an odorant coexisting with the water vapor, such as air, is provided by forming the gas adsorption element in which the high silica zeolite is exposed on the surface of the small pore. A gas adsorbing element which does not adsorb water vapor therein and efficiently adsorbs organic solvent vapor and odorous substances is obtained. The composition of zeolite can be represented by the general formula x M ₂ / n O.Al ₂ O ₃ .y SiO ₂ .zH ₂ O (where M is an alkali metal or alkaline earth metal and n is its valence, y ≧ 1) , Y is usually 1 to 10. For example, 4A type zeolite sold as an adsorbent “Zeolam A-4” by Toyo Soda Kogyo Co., Ltd. is 1.0 ± 0.2Na
₂ is a _{O · Al 2 O 3 · 1.85} ± 0.5 The composition of SiO ₂ · zH ₂ O. Where y is the adsorption capacity is reduced for high silica zeolite material having a large becomes water molecules, polar Using hydrophobic with increased silica component content to be substantially more than 200, an organic solvent vapor, malodorous substances such as non-polar or Better adsorption of less polar substances. There is a method of synthesizing the _{Al 2 O 3 -SiO 2 -H 2} O system - hydrophobicity of the method for obtaining a high-silica zeolite conventional y = 1 to 6 the zeolite directly with how to dealumination Na ₂ O In the former dealumination method, (1) a method of immersing y = 3 erionite, y = 5 mordenite, y = 6 L zeolite or the like in a mineral acid and heating, (2) a method of y = 3 to 6 Heat treatment of Y-type zeolite, mordenite with y = 5 in phosgene gas, (3) M = NH
₄ or H, a method of calcining Y-type zeolite with y = 3 to 6 preferably in the presence of steam; (4) A-type zeolite with y = 2, X-type zeolite with y = 2 to 3, y = 3 6 to 6 Y-type zeolite, etc., by contacting the vapor of silicon tetrachloride at a high temperature, and replacing a part of the aluminum in the zeolite with silicon by a reaction of SiCl ₄ + Al ₂ O ₃ → SiO ₂ + AlCl ₃ . The hydrophobic high silica zeolite that can be used in the present invention may have a value of y of about 8 or more. Of course, in any of the above-mentioned methods, it is necessary that pores of about 3 mm or more are held as an essential requirement as a molecu-larisive. In the present invention, the above-mentioned hydrophobic high silica zeolite forms a gas-adsorbing element in a block shape, that is, a honeycomb shape, having a large number of small holes penetrating through both end faces so that the organic solvent vapor and the malodorous substance can be efficiently adsorbed and separated. I do. As a method of forming a block having a honeycomb structure, for example, a method of mixing the powder of the high silica zeolite described above with kaolinite or another inorganic binder and forming the mixture into a honeycomb shape by a method such as extrusion molding or press molding is also used. A sheet-shaped carrier such as paper or cloth is formed into a honeycomb shape, and formed.
When the high silica zeolite powder is bonded and adhered to the surface and inside of the sheet-like carrier together with the inorganic binder after shaping , the area where the high silica zeolite used comes into contact with the processing gas is greatly utilized. As a sheet-shaped carrier, a sheet formed by combining fibers such as paper, cloth, non-woven fabric and the like so as to have a void is more preferable than a sheet having a smooth and non-permeable surface such as a thin metal plate or a plastic sheet. The high silica zeolite is preferable because it is supported not only on the sheet surface but also in the fiber gap, and a fiber sheet having a bulky fiber and a high porosity is particularly desirable. In addition, desorption regeneration is necessary for gas adsorption, and a pressure swing method that does not require heating can be used for desorption, but desorption regeneration by heating is simpler and more convenient in operation. Inorganic fiber paper which is required to have heat resistance and non-combustibility of the element and is not liable to catch fire, such as ceramic fiber, rock fiber, slag fiber, glass fiber, etc. I do. Asbestos fibers are also inorganic fibers and are not ignitable, but should be avoided because of health problems. Further, the paper is baked at an appropriate stage of the process of manufacturing the gas adsorption element using the paper containing the above-mentioned inorganic fiber as a main component, and a small amount of organic components contained in the paper are burned off. The wavelength 1 of the honeycomb wave is preferably in the range of 2.5 to 4.5 mm, and the wave height h is preferably in the range of 1.0 to 3.0 mm. If the wavelength and wave height are too large, the developed surface area of the gas adsorption element becomes small, and the gas adsorption efficiency becomes low. If the wavelength and the wave height are too small, the pressure loss due to the flow of the processing air and the regeneration air becomes large, and economic operation cannot be performed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing an example of a gas adsorption element of the present invention, FIG. 2 is a cross-sectional view showing a half-wave molded laminate, and FIG. FIG. 4 is a partial cutaway perspective view, FIG. 4 is a graph showing the change in the performance of the gas adsorption element of the present invention depending on the processing inlet air humidity, and FIG. FIG. 6 is a graph showing a change in the performance of the gas adsorption element of the present invention with the element rotation speed, and FIG. 7 is a graph showing a change in the performance of the gas adsorption element of the present invention with the length of the small through-hole. is there. In FIG. 3, 4 is a gas adsorbing element, 5 is a casing, 6 is a separator, 7 is a processing zone, 8 is a regeneration zone, 9 is a geared motor, 11 is processing air, and 12 is regeneration. Indicates air. BEST MODE FOR CARRYING OUT THE INVENTION A low density (approximately 60 to 150 g / m2 basis weight) of a specific gravity of about 0.3 to 0.45 is added to a silica-alumina ceramic fiber by adding a small amount of an organic synthetic fiber and a small amount of an inorganic or organic binder. ² ), inorganic fiber paper made to a thickness of about 0.10 to 0.30 mm, width 40
As shown in FIG. 2, a flat paper is formed by corrugating to a thickness of 0 mm, a wave wavelength of 3.4 mm and a wave height of 1.8 mm and using an adhesive obtained by mixing a synthetic resin such as polyvinyl acetate and an inorganic binder. 1 and the corrugated paper 2 are adhered at the ridge line of the wave of the corrugated paper 2 to obtain a half-wave molded body, and the single-wave molded body is wound around a core material C as shown in FIG. It was formed into a cylindrical honeycomb laminated body having a diameter of 320 mm and having many small through holes 3. NaY zeolite That _{xNa 2 O · Al 2 O 3} · ySiO 2 · zH 2 O as a high-silica zeolite (where x ≒ 1, y ≒ 5
, Z ≒ 9, pore diameter of about 10Å) treated with silicon tetrachloride and a part of the Al ₂ O ₃ was replaced with SiO ₂ zeolite xNa ₂ O OAl ₂ O ₃・ ySiO ₂ zzH ₂ O (where x {1, y ≒ 200, z ≒ 9, pore size almost 10Å) (for example, DAY zeolite from Degussa, Germany) is finely pulverized and dispersed in an aqueous sol of silica or alumina. The product is immersed, high silica zeolite is attached to the fiber gap of inorganic fiber papers 1 and 2 and the surface of the inorganic fiber paper using silica or alumina fine particles as a binder, and after drying, calcined at 450 ° C. for 3 to 4 hours. The organic matter in the sheet was removed, and the zeolite was dehydrated to obtain a gas adsorption element. The attachment ratio of the high silica zeolite to the inorganic fiber paper was about 35% by weight. This calcination may be performed before the impregnation of the zeolite. The gas adsorption element of the present invention obtained in a cylindrical shape as shown in FIG. 1 is, for example, as shown in FIG. And a regeneration zone 8 and a geared motor 9 and a drive belt 10.
The element 4 is rotated to send the processing air 11 to the processing zone 7 and the high-temperature regeneration air 12 to the regeneration zone 8 to adsorb active components such as organic solvent vapor and odorous substances in the processing air 11. And clean air 13 is obtained. In FIG. 3, 14 is a pulley.
, 15 is a tension pulley, 16 is a rubber seal, and 17 is a regeneration air heater. Reference numeral 18 denotes an outlet of the regeneration air, and the organic solvent vapor and other active components are treated in the treatment zone 7.
The concentration ratio is determined by the area ratio of the regeneration zone 8 (8/7). In practice, the operation is performed at a concentration ratio of 5 to 20 times. The length of the cylinder of the element 4 is 400 mm, the rotation speed is 10 r.ph, the amount of regenerating air to the amount of processing air is 1:10, the processing inlet air temperature is 25 ° C. ± 2 ° C., and the flow rate of the processing air and the regenerating air is 2 m /
sec., regeneration inlet air temperature 150 ℃ ± 2 ℃, toluene content in air 550ppm xylene content in air 1100ppm isopropyl alcohol content in air 760ppm n-butyl acetate content in air 340ppm FIG. 4 shows the solvent removal rate (%) when the processing air having the absolute humidity of 2 to 19 g / kg was passed. Here, the solvent removal rate is a value obtained by subtracting a quotient obtained by dividing the solvent content of the processing outlet air by the solvent content of the processing inlet air from one. The solvent removal rate hardly changes even if the concentration of the solvent in the processing inlet air changes within a certain range. As a control example, an example of a hydrophilic zeolite conventionally commercially available, a gas adsorbing element manufactured by the same method as in the above example using "Zeolam F-9" (pore diameter 10 mm) manufactured by Toyo Soda Kogyo Co., Ltd. FIG. 5 shows the results obtained in the same test, that is, the solvent removal rate. As apparent from FIG. 5, in the case of the hydrophilic zeolite, when the absolute humidity at the inlet of the processing air at the element inlet is about 8 g / kg 'or less, the removal rate of all organic solvents is 90% or more. Absolute humidity is 8g / kg '
At higher levels, the solvent removal rate drops sharply. This is a result of the fact that the zeolite used preferentially adsorbs water vapor in the air over molecules of the organic solvent due to its hydrophilicity.
In contrast, for the high silica zeolite used in the present invention, 90% regardless of the absolute humidity of the process inlet air for all organic solvents tested as evident from FIG.
% Or more. The temperature of the processing inlet air is 5 to 50 ° C, and the flow rate is 1 to
3 m / sec., Temperature of regeneration inlet air is 100-160 ° C., concentration of organic solvent vapor is 20
It varied in the range of ２2700 ppm and was tested with different kinds of organic solvents. In each case, 90-100% solvent recovery was shown. When the concentration of the organic solvent vapor in the exhaust gas 18 in FIG. 3 is high, it can be burned or used as fuel for a boiler. Next, in order to observe the change in the solvent removal rate due to the rotation speed of the element, the element obtained by the method of the above embodiment was incorporated into the apparatus shown in FIG. 3, and the inlet temperature of the processing inlet was 15 ° C., and the flow rates of the processing air and the regeneration air were 2 m. / sec., regeneration inlet air temperature 140 ° C, processing inlet air absolute humidity 5.0g FIG. 6 shows the results obtained by measuring the removal rate of toluene by varying the rotation speed of the element in the range of 6 to 26 r.ph under the condition of 500 ppm. As a result, the solvent removal rate changes due to the change in the rotation speed of the element, and it can be seen that the optimum rotation speed with the highest solvent removal rate is about 12 r.ph in the element subjected to this test. Next, in order to observe the change in the solvent removal rate due to the change in the length of the small pores, the thickness of the inorganic fiber paper obtained by the above method and impregnated with zeolite was 0.20 mm, and the wavelength of corrugate was 3.4 mm.
An element having a wave height of 1.8 mm and a length L of the small through hole in the range of 100 mm to 500 mm was incorporated into the apparatus shown in FIG. 3, and the processing inlet air temperature was 15 ° C. and the regeneration inlet air temperature was 15 ° C.
0 ° C, flow rate of process air and regeneration air 2m / sec., Absolute humidity of process inlet air 1
FIG. 7 shows the results of measuring the xylene removal rate by operating under the conditions of 5 g / kg, the solvent vapor concentration in the processing inlet air: xylene 1100 ppm, and the element rotation speed 15 r.ph. Thus, when the length of the small through-hole is about 100 to 300 mm, the adsorption and removal of the solvent is not sufficiently performed. When the length of the small through-hole becomes about 400 mm or more, the adsorption and removal of the solvent becomes 95% or more, that is, almost complete. It turns out that it is useless to make the small through holes longer. INDUSTRIAL APPLICABILITY As the present invention has manufactured a gas adsorption element using a hydrophobic high silica zeolite as an adsorbent as described above, a relatively small amount of an organic solvent vapor or an odor component contained in an inert gas such as air is removed. Very little adsorption of water vapor that is always contained in air during adsorption, and therefore highly efficient adsorption of organic solvent vapor or odor components contained in air or other inert gas regardless of humidity regardless of humidity. It has the effect of being able to be concentrated and removed. In addition, the organic solvent or odor component adsorbed on the element is 100
Since it is almost desorbed at a temperature of about 160 ° C., it is assembled in a rotary regenerative gas adsorber as shown in FIG. 3 to continuously adsorb, concentrate and burn active gas in air or other inert gas. The air containing the concentrated organic solvent vapor can be cooled or the organic solvent can be liquefied and recycled by cooling. When a non-combustible paper or other sheet containing inorganic fibers as a main component is used as a honeycomb laminate for fixing the high silica zeolite, the honeycomb laminate made of the sheet withstands high heat together with the high silica zeolite without fear of ignition. The fire resistance is further improved by firing the non-combustible paper or the honeycomb laminate constituting the element at 450 DEG C. for about 3 to 4 hours to remove a small amount of organic substances contained therein by decomposition or combustion. For example, when high boiling oil mist adheres to the pores of high silica zeolite and the adsorption performance of the element is reduced, hot air of about 350 ° C. is passed through the element to remove the oil mist and activate and reproduce the element. can do. In the production method of the present invention, a thin sheet-like carrier such as noncombustible paper is formed into a honeycomb shape, the honeycomb is fired at 450 to 500 ° C., and a high silica zeolite powder is formed by using an inorganic binder or the like. Impregnated, so that the production can be simplified and inexpensive without the need for special mechanical equipment, and most of the high silica zeolite used in the obtained gas adsorption element works effectively as an adsorbent, and as a carrier, such as non-combustible paper When using inorganic fiber paper made of a composite of fibers and having a high porosity, especially low-density inorganic fiber paper, the high-silica zeolite is fixed not only on the surface of the inorganic fiber paper but also in the fiber gaps, increasing the carrying capacity. It has various characteristic effects.

Claims (1)

[Claims] 1. Main component is an inorganic fibrous sheet - to the door and half-wave shaped body of the half-wave by a shaped body by laminating to form the honeycomb stacked body having many small holes, a silica or alumina aqueous
A hydrophobic high silica zeolite powder having a molar ratio of silica to alumina of about 8: 1 or more is dispersed in the sol, and the honeycomb laminate is immersed in the obtained sol. A method for manufacturing a gas adsorption element, comprising fixing. 2. 2. The method according to claim 1, wherein the high silica zeolite is a zeolite from which most of the aluminum content has been removed. 3. 2. The method according to claim 1, wherein the sheet is formed at a low density. 4. The method for producing a gas adsorption element according to claim 1, wherein the inorganic fiber paper is fired before or after forming the honeycomb laminate. 5. The thickness of the inorganic fiber sheet is about 0.10 to 0.30 mm, and the wavelength of the corrugate is 2.5 to 4.5.
2. The method according to claim 1, wherein the length of the small through-hole is about 100 to 500 mm, the wave height is about 1.0 to 3.0 mm, and the length of the small through hole is about 100 to 500 mm.