SE501507C2 - Process for producing a gas adsorbing element - Google Patents

Abstract

PURPOSE:To improve the performance of the gas adsorbing element by integrally and securing fixing and binding active carbon and/or active alumina and metal silicate aerosol having gas adsorbing activity to a matrix. CONSTITUTION:Paper essentially consisting of inorg. fibers sheeted to a low density is laminated to form the matrix having the shape of the gas adsorbing element which has many small through-holes. A dispersion prepd. by dispersing the powdery or short fibrous active carbon and/or active alumina into an aq. water glass soln. is impregnated in this matrix. The matrix is immersed, after drying, into an aq. soln. of a metal salt, such as A1 salt or Mg salt, which is soluble in water and can generate an insoluble gel-like silicate by reacting with the water glass to form the hydrogel of the metal siliate by the reaction of the water and the above-mentioned metal salt. The gel is then rinsed and dried to integrally and securely fix and bind the active carbon and/or active alumina and the metal silicate aerosol having the gas adsorbing activity to the matrix. As a result, the performance of the gas adsorbing element is additionally improved.

Description

501 507 other metal salt to form metal silicate hydrogel. After washing and drying an element containing zeolite is obtained and metal silicate airgel fixed to the matrix.

In the processes described above, desiccants are used or adsorbent used silica gel, metal silicate gel or zeolite, and each of these adsorbents removes moisture in an inert gas, such as air, through an adsorption process.

Adsorbents other than silica gel, metal silicate gel and zeolite that can be used for adsorption and removal of active gases, eg water vapor, in an inert gas are, for example, other inorganic adsorbent such as activated carbon, alumina gel, activated clay, active magnesium oxide and the like, as well as various organic adsorbent. The object of the present invention is to further improve the gas adsorbent elements produced according to the mentioned older patent applications, thereby also adding inorganic adsorbents which are very heat resistant.

In the manufacture of dehumidifiers or other gas adsorbents elements by utilizing reactions between water glass and a acid or between water glasses and an aqueous solution of metal salt have mixed mixtures of different inorganic adsorbents been tried, such as activated carbon, activated alumina, activated clay, active magnesium oxide and the like, in the water glass. Elements have set in the manner described above, and the effect of these elements has tried. It has been found that a mixture of water glasses and powdered or short-fiber activated carbon provides a dehumidifier or other gas adsorbent element with remarkably high humidifying effect for a process gas with high humidity. By mixing active alumina with water glass, a reduction of humidifier or other gas adsorbing element that can provide a gas with ultra-low dew point, as well as the element described above containing land zeolite. The present invention is based on these covers.

For the production of the matrix you can use any preferably paper which is resistant to the gas to be treated and the active gas to be adsorbed and removed and 501 507 which can be laminated and shaped into a honeycomb structure. If, for example, it produced gas adsorbent element shall be used for dehumidification and heated regeneration air are used for desorption or regeneration, however, paper of non-organic non-combustible fibers, such as paper, are mainly of ceramic fibers, glass fibers, carbon fibers, mineral fibers fibers, slag fibers or mixtures thereof.

You can use water glass (sodium silicate) No. 1, No. 2 or No. 3 and also potassium silicate. Theoretically you can use any acid that is stronger than silicic acid. With respect to the cost, work environment and other factors are, however sulfuric acid the most suitable acid. Such as water-soluble metal salt can theoretically use all salts of divalent or trivalent precious metals. However, the industrially useful salts are aluminum salts, magnesium salts and calcium salts. Among these aluminum sulphate and magnesium sulphate can produce silicates in gel state with high adsorption capacity, as previously written in the Swedish patent application 8601546-8.

When a matrix impregnated with water glass solution before the immersion in acid or metal brine is heated to water glass solution to form hydrated or semi-solid water glass with a water content of 5-45%, lust for water glass by dissolving in the acid or metal salt solution ningen.

The invention is described in more detail below with reference to the accompanying drawing, on which Fig. 1 schematically illustrates the first step of the process according to the invention; Fig. 2 is a perspective view of a matrix; Fig. 3 is a perspective view of a rotary dehumidifier, wherein some parts have been removed for clarity; and Fig. 4 is a diagram showing the dehumidifying properties of various elements of the present invention and prior art element.

Preferred embodiments of the invention are described below in detail. 501 507 Example 1 Fig. 1 shows a device for carrying out the first the step of the present invention, i.e. the lamination step. IN the figure shows a pair of knurled rollers 1 and 2 with desired embodiments jump along the perimeter. These rollers interlock in the manner shown method, and a press roll 3 with a smooth cylindrical surface is pressed against it knurled roller 2. The roller 3 rotates with approximately the same circumferential speed as the roller 2. Fig. 1 also shows two devices 4 and 5 for application of adhesive. These devices consist of adhesive vessels 4a and 5a and rollers 4b and 5b for application of binder. The binder vessels 4a and Sa are filled with binder agent 6 consisting of an aqueous solution of water glass. The wonders the parts of the rollers 4b and 5b are immersed in the binder solution.

The roller 4b is mounted just below the knurled roller 2.

It is based on rolls of very porous papers 7 and 8, which consist of 70-90% ceramic fibers, 5-20% pulp and 5-10% binder and has a thickness of 0.1-0.5 mm and a bulk density of not more than 0.5 g / cm3. The paper is guided between the knurled rollers 1 and 2 so as to obtain corrugated paper 7a. The corrugated paper 7a is passed on of the roller 2 and is brought into contact with the roller 4b, the bonding means 6 is applied to the ridges by the weighing paper 7a. Wave paper 7a and the planar paper 8 is passed together between the knurled roller 2 and the press roll 3, the two papers being bonded together a one-sided corrugated sheet 9. Binder 6 is applied to the ridges of the one-sided corrugated sheet 9 by means of the roller 5b in the scheme 5 for applying adhesives. A cylindrical matrix 11 with many small channels through both ends (see Fig. 2) is then set by winding the glued corrugated sheet 9 about an axis 10.

To an aqueous solution of water glass No. 1 (SiO2: Na2O = 2.1: 1) 5-25% by weight of finely powdered or short-fiber activated carbon is added.

The matrix prepared above is impregnated with the resulting the mixture and then dried for about 1 hour at 50-100 ° C to conversion of the water glass to hydrated or semi-solid water glass with a water content of 5-20%. The amount of water glass applied plus activated carbon is suitably 1-2.5 times the weight of the matrix. The matrix S01 507 then immersed in 21% aqueous solution of aluminum sulphate, and the solution is stirred to form hydrogel of aluminosilicate by reaction between the water glass and the aluminum sulphate. It so- as a by-product formed the sodium salt and the excess aluminum sulfate is removed by washing. The matrix is then dried through heating, whereby a solid dehumidifying element is obtained standing of a honeycomb structure of aluminosilicate airgel, which contains uniformly distributed activated carbon and is reinforced with the matrix of the paper of inorganic fibers. The airgel has been formed on the paper and in the openings between the fibers of the paper.

The same result can be obtained if instead of aluminum sul- barrel solution is used an aqueous solution containing about 15-30% of another metal salt, such as monobasic aluminum phosphate, aluminum nitrate, magnesium sulphate or the like.

Example 2 Paper with a bulk density of only 0.3-45 g / cm3 and with a thickness of about 0.15-0.25 mm is produced by small amounts pulp and binder are added to silicon-type ceramic fibers dioxide-alumina. This paper is corrugated and used for preparing a matrix 11 in the same manner as described in the example 1, using as a binder a mixture of synthetic resin, for example polyvinyl acetate, and an inorganic binder, such as silica sol. The matrix is then heated in air to a temperature of about 400oC for removal of organic materials, namely those the organic fibers and binder in the paper and the organic adhesive used for lamination. Water glass no. 3 (SiO2: N & 2O = 3.1: 1) diluted with water to a solids content of 30-45%. To the water glass solution is added 10-20% by weight of Zeolam A-4, a synthetic zeolite from Toyo Soda Co. Ltd., and 5-20% by weight of active powder aluminum oxide, after which the whole is mixed uniformly. The above the written matrix is impregnated with this mixture and then dried by heating, the matrix is then immersed for 3-4 hours in a 20% aqueous solution of magnesium sulphate, whereby hydrogel of magnetic Silicate is formed by chemical reaction between the water glass and the magnesium sulfate. This hydrogel adheres to the matrix, which washed to remove the by-product sodium sulphate and the shot of magnesium sulfate and then dried. Hereby obtained 501 507 a dehumidifying element with a honeycomb structure consisting of silicate silica airgel, which contains synthetic zeolite and active alumina in a uniformly dispersed state and which is reinforced with the matrix of the ceramic fiber paper. The airgel has formed on the paper and in the openings between the fibers of the paper.

The matrix can similarly be formed of paper consisting of of ceramic fibers, glass fibers and pulp or paper mainly consisting of carbon fibers or activated carbon fibers. Instead for the magnesium sulphate solution one can similarly use one aqueous solution containing 15-30% of another metal salt, such as aluminum sulphate, monobasic aluminum phosphate, aluminum nitrate or similar.

Example 3 A matrix 11 is prepared in the same manner as in Example 2 with use of a paper consisting of 70-94% ceramic fibers, 2-22% pulp and 4-8% binder. The paper has a thickness of 0.1-0.5 mm and a bulk density of 0.3-0.6 g / cm 3. The matrix heated in air to a temperature of about 400 ° C to remove the organic materials in the paper and in the binder. The matrix then impregnated with an aqueous solution of water glass No. 1 (solids content 25-45%) containing 5-25% by weight of powder activated carbon. The impregnated matrix is heated to about 90 ° C for conversion of the water glass into hydrated or semi-solid water connected with a water content of 5-20%. The amount of water glass placed plus activated carbon is about 1.5-3 times the weight of the matrix. The matrix down- then immersed in a 3 N aqueous solution of sulfuric acid with stirring.

By reaction between the water glass and the sulfuric acid is formed silica hydrogel (containing activated carbon), which adheres to the matrix of ceramic fibers. The matrix is washed to remove bi- the product sodium sulfate and excess sulfuric acid and dried then by heating. In this case, a dehumidifying element is obtained mainly consisting of silica airgel, which contains similar formally distributed activated carbon and is firmly connected to the edge matrix. The airgel is formed on the paper and in the openings between the fibers of the paper. 501 507 Instead of sulfuric acid, you can also use other acids, such as hydrochloric acid or phosphoric acid, as long as these acids are not and affects or destroys the ceramic fibers or the active coal. However, sulfuric acid is the most suitable acid with regard taken at cost, work environment and the like.

The gas adsorbent prepared according to the present invention the dehumidifying element can be used, for example, in dehumidifiers for dehumidification. gas. Fig. 3 shows a rotary dehumidifier comprising a dehumidifying element 11, which is rotated in a housing 12. By means of a separating member 13, the element is divided into a working zone 14 and a regeneration zone 15. The element 11 is rotated by means of a gear motor 16 and a drive belt 17 with a speed as low as approx 5-20 revolutions per hour. Process air 18 is led into the working zone 14, and hot regeneration air 19 with low humidity is led into the regeneration The process air is dehumidified, whereby dry air is held. In Fig. 3, the numeral 21 denotes a pulley, the numeral 22 denotes denotes a tension roller, the number 23 denotes a rubber seal, and the number 24 denotes a heating device for regeneration the air.

Fig. 4 shows the equilibrium amount of adsorbed moisture (% by weight) per unit weight of adsorption medium in different dehumidification elements at different relative humidities. Curve C in Fig. 4 shows the values obtained held with the element according to Example 1, and the curve S shows values obtained with an element consisting mainly of aluminum silicate airgel, ie an element produced without the activated carbon in example 1 mainly in the way described in the Swedish patent application 8601546-8. Curve A shows values obtained with one elements according to Example 2, and the curve Z shows values obtained with an element consisting mainly of magnesium silicate and syn- aesthetic zeolite, ie an element produced without the active aluminum the nia oxide in Example 2 essentially in the manner described in the Swedish patent application 8801470-9. Curve B shows the values held with an element according to Example 3, and curve H shows values obtained with an element consisting mainly of silica aerosols gel, i.e. an element prepared without the activated carbon in Example 3 mainly in the manner described in the Swedish patent application 501 507 s 8504494-9. Diagram 4 clearly shows that an element containing powdered or short-fiber activated carbon very good dehumidifying properties, especially for process gas with high humidity. When the element contains active alumina, it shows remarkable dehumidifying properties, especially for process gas with low humidity, as is the case with mixing of synthetic zeolite.

The water used in the process according to the invention the glass not only completely wets the surface of the paper of fibers due to the high affinity of the inorganic fibers the fibers, but it also penetrates far into the spaces between the inorganic fibers of the paper, so that it can form silica hydrogel or metal silicate hydrogel by reaction with the acid or the metal salt solution. Silica hydrogel or metal silicate hydrogel, wherein fibrous or powdered activated carbon and / or active alumina powder and / or zeolite powder have dispersed uniformly, is thus firmly bound in the interior of the matrix of low density paper. When drying for conversion of the hydrogel to the airgel, the shrinkage is insignificant, and the airgel cracks not or broken into smaller pieces. A strong airgel thus maintained. This airgel as well as activated carbon and / or activated alumina and / or zeolite exhibit a remarkable improved dehumidification ability in collaboration with each other. Although only dehumidifying elements have been described above, can the gas adsorbents prepared according to the present invention the elements are of course also used for adsorption and removal active gases other than water vapor, such as nitrogen oxides, sulfur oxides, carbon monoxide, ammonia and various foul-smelling organisms technical subjects. An element containing activated carbon can be remarkably worth well adsorb and remove malodorous organic substances or solvent vapors with relatively low polarity. One elements containing active alumina can remarkably well adsorb and remove relatively large inorganic gases polarity.

Claims (3)

501 507 Patent claims Process for producing a gas-absorbing element comprising silicate or silica airgel, characterized in that a low-density paper consisting mainly of inorganic fibers is laminated to form a matrix with numerous small channels: (b1) the matrix is impregnated with an aqueous solution of water glass, in which powdered or short-fiber activated carbon and / or active alumina has been dispersed; (c1) the impregnated matrix is dried; (dQ the dried matrix is immersed in an aqueous solution of a water-soluble metal salt which may form an insoluble silicate in the gel state, such as an aluminum salt, magnesium salt or the like, wherein a water-insoluble metal silicate hydrogel is formed by reaction between the water glass and the metal salt; (e1) the treated matrix is washed; and (Q) the washed matrix is dried to form of a gas adsorbent element, wherein activated carbon and / or activated alumina and metal silicate airgel with gas adsorbing ability a are firmly bound to the matrix; elharatt (a2) low density paper consisting mainly of inorganic fibers is laminated to form a matrix with numerous small channels: (b2) the matrix is impregnated with an aqueous solution of water glass, in which powdered active alumina has been dispersed; A (c2) the impregnated matrix is dried; (d2) the dried matrix is immersed in an acid, such as sulfuric acid, whereby silica hydrogel is formed by reaction between the water glass and the acid; 'I V' (e2) the treated matrix is washed; and (f2) the washed matrix is dried to form a gas adsorbent element, wherein active alumina and silica airgel having gas adsorbing ability are firmly bonded to the matrix. 10 5012 507. Process according to Claim 1, characterized in that a dehumidifying element is produced. Process according to Claim 1 or 2, characterized in that zeolite is also dispersed in the aqueous solution of water glass.