JP2015509832A - Desiccant-supporting honeycomb chemical filter and manufacturing method thereof - Google Patents

Abstract

The present invention is a desiccant-carrying honeycomb chemical filter comprising a matrix formed from a substrate having a desiccant produced in situ or deposited on a substrate, wherein the desiccant comprises a metal silicate, Selected from the group consisting of silica gel, molecular sieve, activated alumina, activated carbon or hydrophobic zeolite and any mixtures thereof, wherein the substrate is an oxidizing agent, or an alkali metal hydroxide, or a strong or weak acid, or a reducing agent A chemical filter is provided that is further impregnated with one or more of the following:

Description

  The present invention relates to a chemical filter for removing contaminants from air present in a factory environment or a home environment. More specifically, the present invention relates to a desiccant-carrying honeycomb chemical filter. The present invention also relates to a method for producing a desiccant-carrying honeycomb chemical filter.

  As described above, the present invention relates to a desiccant-carrying chemical filter, such as a honeycomb chemical filter, for removing contaminants from air present in a factory or home environment. The present invention also provides a method for producing a desiccant-carrying honeycomb chemical filter.

  The contaminants to be removed are typically gaseous contaminants, but may also include contaminants in the form of fine droplets that cannot be easily removed by conventional methods.

  The term “desiccant” as used herein is intended to encompass both macroporous and microporous desiccants. The desiccant or desiccant-carrying honeycomb matrix used in the present invention is impregnated with various impregnating materials. The present invention also provides a method for removing gaseous pollutants, contaminants and odors from industrial processes using the chemical filter. The present invention relates to the production of macroporous / microporous desiccant or desiccant-supported honeycomb matrix impregnated with various impregnants to remove gaseous pollutants or odors in the air. Also related to the method.

  It is well recognized that molecular contaminants carried by air are difficult to manage because it is difficult to count and / or measure such particles present in a given area. This difficulty is mainly due to the fact that gas is different from particles. The impact of pollutants not only on human life but also on productivity can be serious if not properly paid attention. The presence of chemical contaminants can alter the chemistry of the surrounding environment and adversely affect human life and productivity, even at concentrations in the parts per billion (ppb). Traditional filters are gaseous contaminants, especially inorganic contaminants that are not detected by particle detectors, such as ammonia, amines, ozone, sulfur oxides, nitrogen oxides, sulfides, and other molecular contaminants. Insufficient in protecting a given environment from factors.

  The challenges in the art will be understood from the following commentary on several solutions that can be used to remove volatile organic components that make up a significant portion of the airborne molecular contaminants, especially in factory environments. .

  One challenge in the art is to control odor while ensuring that the desired humidity level for human comfort and health is not sacrificed. However, since existing dehumidifying devices remove excessive moisture from the air or odor removal is insufficient, maintaining an appropriate level of humidity at the same time as odor control is a particular problem.

  Odors in a factory environment, and also in a non-factory environment such as a passenger compartment of a transportation vehicle, are attributed to volatile organic compounds present in the circulating air. These organic compounds are high-level but relatively low in engine exhaust, solvents, gas turbines, cogeneration plants, petrochemical plants, and in many industrial processes where the waste gas contains substances such as solvent vapors, inks, paints, etc. Formed at low concentration. Volatile organic compounds, whether saturated, unsaturated or aromatic, not only contain hydrocarbons, but also oxygenated substances such as alcohols, esters, ethers and acids, nitrogen-containing compounds (mainly amines), Sulfur-containing materials (mercaptans and thioethers) and halogen-containing materials, especially chlorine-substituted hydrocarbons, also contain organic fluorides and bromides. The presence of such compounds in the gas stream is recognized as a health risk and / or causes the gas stream to have an unpleasant and undesirable odor.

  Conventional solvent recovery methods from humid air typically included an adsorption system that was operated until the solvent concentration in the outlet gas stream reached a detectable predetermined breakthrough level. When this level was reached, the gas flow to the adsorber stopped. Then, depending on the inlet relative humidity of the solvent-loaded gas stream, the adsorbent bed contained solvent, other condensable organic contaminants, and some amount of water.

  This method was subsequently modified by the introduction of a saturated or superheated hot inert gas or steam. This moves the solvent from the adsorbent and produces a solvent / water mixture upon condensation. Typically, two adsorbent beds were used, with one bed regenerating while the other bed was adsorbing.

  Further developments in regeneration and recovery of solvent from the adsorbent bed include the use of inert gas or air and the low temperature condensation of the solvent from the gas / air during regeneration. However, these techniques cannot be applied directly to all the given situations that are needed.

  It is known that volatile organic compounds can be removed from the air by adsorption, such as temperature swing adsorption. Air streams that require treatment can be found in most chemical and manufacturing plants, especially those that use solvents. At concentration levels from 500 ppm to 15,000 ppm, VOC recovery from the stream used to thermally regenerate the activated carbon adsorbent is economically reasonable. Concentrations above 15,000 ppm are typically in the explosion range and require the use of hot inert gas rather than air for regeneration. Below about 500 ppm, recovery is not economically reasonable, but environmental concerns often require disposal after recovery by adsorption. Activated carbon is the traditional adsorbent for these applications and is the second most common application.

  U.S. Pat. No. 4,421,532 discloses a method for recovering VOCs from factory waste by temperature swing adsorption, including the use of hot inert gas circulating in a closed cycle to desorb VOCs.

  One device used to dry air in an isolated area such as a house, ship or building until 0.001 lb of water per pound of air is described in US Pat. No. 4,134,743 . This document discloses a method and apparatus in which the adsorbent is a wheel consisting of a thin sheet or layer of fibrous material containing about 10% to 90% by weight of a well-divided molecular sieve material. . The apparatus comprises means for sending the air to be treated in one direction through the wheel and means for sending a counter flow of a renewable air flow to the air to be treated. Further, the cooling flow is provided in the direction in which the cooling flow co-flows with the air flow.

  U.S. Pat. No. 4,887,438 discloses a desiccant assisted air conditioning system for delivering dehumidified and cooled air to a conditioned space based on an adsorbent wheel. Meckler teaches the use of silica gel, or preferably a desiccant wheel coated with a hygroscopic salt, lithium chloride, to remove moisture from the air. This reference teaches the use of waste heat from a refrigerated condenser to heat the reactivated air, increasing the pressure ratio of the positive displacement compressor to increase the "thermal dumpback" In order to deal with the problem, the liquid refrigerant is injected into the compressor. Temperature dumpback is the accompanying heat conducted from the desiccant wheel to the treated air that occurs in response to the wheel being exposed to heated regeneration air. This associated heat provides an overall cooling load for the cooling system.

  U.S. Pat. ing. The gas to be dehumidified is sent first to a rotor coated with silica gel and then to a rotor coated with zeolite. These rotors supply a heated gas stream through the second rotor and then the first rotor so that the adsorbent of the first rotor is regenerated at a lower temperature than the zeolite of the second rotor. Is played by. Part of the treated gas is used to cool the rotor by counterflow after regeneration.

  The most common technique for removing low concentrations of volatile organic contaminants from a gas stream by adsorption is illustrated in US Pat. No. 4,402,717. This document teaches an apparatus for removing moisture and odor from a gas stream comprising a cylindrical honeycomb structure of corrugated paper that is uniformly coated with an adsorbent and formed into a disk or wheel shape. Multiple parallel flow channels covered with adsorbent formed by corrugated paper were separated into areas for removing water and odor, which are constituents of gas, and areas for regeneration of adsorbent Acts as a plurality of gas passages. These regions for removal and regeneration can transition continuously as the wheel rotates circumferentially around its centerline. A labyrinth seal separates the outer surface of the rotating structure from the sealed cylindrical wall of the casing.

  One of the challenges associated with prior art attempts to use a honeycomb matrix is the adsorbent used. Hydrophilic adsorbents such as silica gel are typically selected for dehumidification applications, but are poor adsorbents for removal of volatile organic contaminants. One combination of such methods is described in US Pat. No. 5,181,942. On the other hand, hydrophobic adsorbents such as high silica zeolite are typically recommended for VOC removal applications, but are poor adsorbents for dehumidification applications. Thus, in applications for both dehumidification and VOC removal, typically both types of adsorbents may be required.

  Numerous attempts have been made to use a single adsorbent for both actions. Furthermore, the adsorbent coated paper and some adsorbent salts have a limited range of humidity and temperature that can maintain structural integrity. This disadvantage also limits the regeneration medium for dry, medium temperature gases and air. The contact between the adsorbent and the gas stream, and thus the adsorption capacity for VOCs, is limited to a very thin layer of adsorbent on the surface of the fiber. This feature also limits the longest allowable life of the adsorbent wheel, resulting in frequent wheel replacement.

  A chemical filtration strategy has been recognized as ideal for use in controlling molecular contaminants carried by air. However, the use of a desiccant based on a honeycomb matrix has not been generally considered because it is difficult to reliably achieve both humidity control and chemisorption.

  A filter is generally a device, such as a membrane or layer, that is designed to block or contain objects or substances while allowing other objects or substances to pass through. There are generally three types of filtration media: mechanical, biological and chemical. A chemical filter is preferred to remove gaseous pollutants in a given environment, because the chemical filter controls the oxidizing action, so that the adsorbent / impregnated adsorbent such as potassium permanganate adsorbs odors. This is because air purification is realized by performing both absorption and absorption.

  Gaseous contaminants can be either inorganic or organic. The selection of adsorbents that adsorb gases or reactants that adsorb gas / impregnants to remove gaseous contaminants is very important for chemical filter media. As discussed above, a single chemical filter media may not be able to adequately control multiple contaminants or multiple classes of AMC.

U.S. Pat.No. 4,421,532 U.S. Pat.No. 4,134,743 U.S. Pat.No. 4,887,438 U.S. Pat.No. 5,242,473 U.S. Pat.No. 4,402,717 U.S. Pat.No. 5,181,942

  One object of the present invention is to provide an impregnating agent in which a desiccant is generated in situ and impregnated with an oxidizing chemical, acidic or alkaline chemical, or reducing chemical to remove / contain gaseous contaminants Is to provide a desiccant-carrying honeycomb chemical filter that is significantly higher than would be possible in the art.

  The main object of the present invention is to increase the ability to remove gaseous pollutants, whether acidic, alkaline or organic, by extending the impregnating agent and extend the lifetime of chemical filters. .

  A further object of the present invention is to make a desiccant-supported honeycomb matrix with or without activated carbon or hydrophobic zeolite to impregnate various impregnants / reactants to remove gaseous contaminants. is there.

  Another object of the present invention is to provide a desiccant-carrying honeycomb matrix with minimized pressure loss. The desiccant may or may not contain activated carbon or hydrophobic zeolite and may or may not be impregnated with an impregnating agent to facilitate the removal of various contaminants.

  A further object of the present invention is to have an activated carbon or a hydrophobic zeolite, which can save energy while at the same time facilitating odor control, and is impregnated with various impregnating agents. It is to provide a desiccant-supported honeycomb matrix chemical filter that may or may not be impregnated.

  Accordingly, in order to overcome the problems encountered in the prior art, as described herein below, the present invention provides a honeycomb matrix comprising a desiccant prepared in situ for use as a chemical filter. To do.

  The present invention is a desiccant-supported honeycomb chemical filter comprising a matrix formed in situ or having a desiccant deposited on the substrate, the desiccant comprising a metal silicate, silica gel, molecular Selected from the group consisting of sieves, activated alumina, activated carbon or hydrophobic zeolite, and any mixtures thereof, wherein the substrate is an oxidizing agent, or an alkali metal hydroxide, or a strong or weak acid, or a reducing agent. A chemical filter is provided that is further impregnated with the seed or species.

  The substrate includes an inorganic or organic material or a mixture thereof.

  In a further embodiment, the material is in the form of fibers or pulp.

  In a further embodiment, the inorganic fibers are selected from the group consisting of glass fibers, kraft paper, ceramic paper and any combination thereof, preferably glass fibers.

  In another embodiment, the desiccant is selected from a combination of metal silicate and silica gel or metal silicate and activated carbon and / or a hydrophobic desiccant such as a zeolite selected from HISIV and ZSM-5.

  The metal silicate is selected from potassium silicate and sodium silicate, preferably the silicate is neutral grade sodium silicate.

In a preferred embodiment, the ratio of SiO ₂ to Na ₂ O in sodium silicate is in the range of 1: 2.0 to 1: 4.0, preferably in the range of 1: 3.

  In another embodiment of the present invention, the impregnating material is selected from the group consisting of potassium permanganate, sodium permanganate, potassium hydroxide, sodium hydroxide, phosphoric acid and sodium thiosulfate.

  In a further embodiment of the invention, the filling rate of the impregnating material in the matrix ranges from 4% to 40%, preferably about 20%.

  In a further embodiment of the invention, the binder is preferably absent.

  In a further embodiment of the invention, the basis weight of the substrate is in the range of 50 gsm to 150 gsm, preferably in the range of 80 gsm to 120 gsm.

The present invention
(i) a step of dehydrating the macroporous or microporous desiccant-supporting honeycomb matrix at a temperature of 100 ° C. or higher;
(ii) a desiccant-carrying honeycomb comprising a step of impregnating a dehydrated desiccant-carrying honeycomb matrix with a suitable impregnating agent and then drying the matrix while maintaining a moisture content in the range of 15% to 30%. A method of manufacturing a chemical filter is also provided.

When used in a situation involving in situ generation of a desiccant, the method comprises the following steps:
(i) treating the substrate material with a desiccant-forming substance or desiccant selected from the group consisting of metal silicates, silica gels, molecular sieves (hydrophilic or hydrophobic), activated alumina, activated carbon and any mixtures thereof A desiccant-forming substance in the form of a solution having a concentration in the range of 15% to 40%,
(ii) drying the treated material to reduce its moisture content to a range of 15% to 40%;
(iii) immersing the substrate matrix in a water-soluble metal salt or strong or weak acid to form a hydrogel to obtain a gel matrix;
(iv) washing the gel matrix obtained in step (iii) to remove excess reactants and undesirable by-products;
(v) drying the gel matrix under temperature controlled conditions to convert the hydrogel to an airgel matrix;
(vi) treating the airgel matrix with one or more of an oxidizing agent, or an alkali metal hydroxide, or a strong or weak acid, or a reducing agent;
(vii) drying the airgel matrix treated in the above step (vi) at a temperature in the range of 50 ° C. to 140 ° C. to obtain the chemical filter.

  The present invention provides a solution to the problem in the art to reliably achieve maximum efficiency of adsorption of chemical contaminants using a honeycomb-based chemical filter that uses a desiccant. The honeycomb matrix can be formed from a variety of substrates such as plastic sheets, metal / aluminum foils, organic and / or inorganic fiber substrates that are “paper” like, and may be completely porous. The amount or rate of desiccant material deposition on the substrate is generally a function of the choice of substrate, the amount of desiccant deposited or filled and the temperature at which the air / matrix is intended to be used. Known techniques for preparing a matrix by depositing or filling a desiccant onto a substrate include coating, impregnation and in situ synthesis.

  Coating and impregnation are selected when the desiccant powder is produced in large quantities and intended for industrial applications other than HVAC air treatment. In situ synthesis is generally selected for desiccant materials such as silica gel and metal silicates.

  In the desiccant-carrying honeycomb chemical filter of the present invention, the desiccant is generated in situ and impregnated with an oxidizing chemical, acidic or alkaline chemical to remove / contain gaseous contaminants, and the percentage of impregnating agent filled Is significantly higher than is considered possible in the art.

  Surprisingly, this increased the ability to remove gaseous contaminants, whether acidic, alkaline, or organic, and extended the lifetime of chemical filters through the use of higher amounts of impregnation.

  The desiccant-supported honeycomb matrix can be made with or without activated carbon or hydrophobic zeolite to impregnate various impregnants / reactants to remove gaseous contaminants. Another salient feature of the present invention is that the pressure loss in the desiccant-carrying honeycomb matrix is minimized. The desiccant may or may not contain activated carbon or hydrophobic zeolite and may or may not be impregnated with an impregnating agent to facilitate the removal of various contaminants.

  The desiccant-carrying honeycomb matrix chemical filter of the present invention also provides energy savings and may or may not have activated carbon and may or may not be impregnated with various impregnating agents, On the other hand, odor control can be promoted.

  As mentioned above, the air to be treated, in particular outside air, generally contains several gaseous pollutants such as, for example, VOCs, odors and the like. It is desirable to remove these with a desiccant matrix. In the air to be treated, especially when the air is pre-cooled to near saturation, such gaseous contaminants are sometimes water-soluble and condense together in the macroporous desiccant primarily by capillary adsorption. The prior art includes several references to the use of microporous desiccants. However, these desiccants generally have limited capillary adsorption and thus limited adsorption of gaseous contaminants.

  The prior art also limits the filling capacity for both the desiccant and any impregnating agent due to the fact that the desiccant is generally coated or impregnated on the substrate. Thus, adsorption in these cases is a surface phenomenon. This inevitably leads to the use of lower density paper (typically in the range of 20 to 80 gsm thick). The need for substrate coating is generally a limiting factor in substrate selection, and it has been considered impossible to increase the density of the substrate without compromising the surface area required for adsorption.

  The problems encountered in the art are solved in the present invention by providing a honeycomb matrix comprising desiccant prepared in situ for use as a chemical filter, as described herein below. The

  The present invention is achieved by a macroporous or microporous desiccant-supported honeycomb matrix. The substrate is made from a variety of inorganic or organic materials or combinations thereof. The material can be fiber or pulp. The inorganic fiber is selected from glass fiber, kraft paper, ceramic paper and the like, and is preferably glass fiber. Desiccants that can be synthesized in situ preferably comprise a metal silicate / silica gel that provides a high adsorption capacity.

The invention will now be described with reference to exemplary, non-limiting embodiments that use glass fibers as a substrate. The method includes laminating water glass treated / impregnated glass fibers in either honeycomb or block form. Treating the matrix with a water soluble salt (whether divalent or trivalent) or any acid (whether organic or inorganic) to produce a water glass silicate with a pore diameter in the range of 10 to 70 mm, converted to an active desiccant material having a 0.10gm / cc~0.80gm / surface area of the pore volume and 300m ² ~700m ² of cc.

  The desiccant-carrying honeycomb matrix is generally a flat and / or corrugated sheet of fiberglass substrate with active desiccant synthesized in the pores. The fiberglass substrate used in the present invention is a highly porous material having a fiber diameter of 4 microns to 15 microns, a fiber length of 6 mm to 10 mm, and a thickness in the range of 0.10 mm to 0.75 mm. The fiberglass substrate used in this method has a binder content of 8% or less, and the preferred binder used to make the substrate is a combination with polyvinyl alcohol or acrylic. It is desirable to use a low content of organic binder in the substrate so that the percentage of organic content in the desiccant-supported honeycomb matrix is also reduced.

  In general, when a water-soluble silicate desiccant is generated in situ, the need to add an external binder is avoided. When treated with a suitable reactant, the silicate material itself functions as a desiccant. However, it is desirable to add additional binder material when coating the desiccant on the matrix. For this purpose, water-soluble silicates can be used. Alternatively, commercially available binders may be used when the desiccant is coated on the matrix.

  The basis weight of the substrate used in the method is between 50 gsm and 150 gsm, preferably between 80 gsm and 120 gsm. The fibers used in making such a substrate can be insulating grade fibers. The corrugated flat sheet is first passed through a water glass solution of the desired concentration (15% -40%, preferably 30%) with or without activated carbon material or hydrophobic zeolite. The sheet is dried in a drying chamber, preferably using infrared heating, to ensure that the moisture content is in the desired range of 15% to 40%, preferably 20%. Other types of water-soluble silicates such as potassium silicate can be used, but sodium silicate is preferred because of its cost efficiency, high solubility of its by-products, higher bond strength and availability.

  In order to impregnate the fiberglass substrate, it is preferred to use a neutral grade water-soluble silicate, preferably sodium silicate. It has been observed that the presence of high alkali content in alkaline grades compared to neutral grade silicates necessitates the use of large amounts of reactants. Alkaline grade sodium silicate also provides a higher gelation rate than neutral grade silicate. This gelation rate adversely affects the properties of the desiccant.

  The method of in situ synthesis of the desiccant material on the substrate can be performed simultaneously with the deposition of activated carbon and / or a hydrophobic zeolitic material such as HISIV or ZSM05. The use of activated carbon and / or hydrophobic zeolitic material improves the level of odor removal and further significantly improves the structural strength of the substrate itself. Activated carbon (and / or hydrophobic zeolitic material) in powder form is mixed with water-soluble silicate or any suitable binder mineral or binder organic prior to in situ desiccant formation. This makes it possible to improve the odor control, VOC adsorption and the structural strength of the matrix itself by capturing / encapsulating the activated carbon particles or hydrophobic zeolite in the desiccant.

  Corrugated sheets are made by passing a flat sheet impregnated with silicate (or silicate and activated carbon or hydrophobic zeolite) through a toothed roller. Single facer unit for moisture content of sheets impregnated with silicate or silicate and activated carbon or hydrophobic zeolite, water glass grade, corrugated roller, clearance control on adhesive roller, and adhesive curing heating It is important when making. The corrugated sheet and the flat sheet are pressed together using an additional roller made of the same material used for corrugation. Even while making a single facer with the same water glass used for impregnation, it is possible to avoid the use of adhesives in order to avoid powdering after synthesis or a greater pressure drop. preferable. This is achieved by keeping the moisture content in the flat sheet higher.

A single facer, which is a combination of a flat sheet and a corrugated sheet, can be converted to either a block or cylindrical shape. Preferably, neutral grade sodium silicate is sequentially applied prior to lamination or winding to ensure single facer adhesion. Applying a SiO ₂ : Na ₂ O in the range of 1: 2.0 to 1: 4.0, preferably 1: 3.0, prior to winding or laminating of the single facer provides additional strength to the honeycomb matrix. Next, the produced honeycomb matrix is dried to promote sheet adhesion. When the ratio of SiO ₂ : Na ₂ O is ≦ 2, the bonding force is weaker, and when the ratio of SiO ₂ : Na ₂ O exceeds 4.0, the adhesive force is smaller.

Another advantage of using neutral grade silicate is the speed of drying. Since water retention is a linear function of alkalinity, water loss is affected by the SiO ₂ : Na ₂ O ratio. The higher the silicate ratio, the less water. Drying of more alkaline silicates with a SiO ₂ : Na ₂ O ratio in the range of 2.0-2.6 is slower than silicates with SiO ₂ : Na ₂ O in the range of 3.0-3.3.

The honeycomb matrix made above, either in block form or cylindrical form, is then converted into various proportions of water soluble metal salts or inorganic or organic strong or weak acids and other forms that produce silicate hydrogels. Immerse in the solution. The reaction between the water glass silicate and the metal salt forming the insoluble metal silicate hydrogel is given in the table below.
Na ₂ Si0 ₃ + Al ₂ (S0 ₄ ) ₃ → Al ₂ (Si0 ₃ ) ₃ + Na ₂ S0 ₄
Na ₂ Si0 ₃ + MgS0 ₄ → MgSi0 ₃ + Na ₂ S0 ₄
Na ₂ Si0 ₃ + MgCl ₂ → MgSi0 ₃ + NaCl
Na ₂ Si0 ₃ + AICl ₃ → Al ₂ (Si0 ₃ ) ₃ + NaCl
Na ₂ Si0 ₃ + HCl → H ₂ Si0 ₃ + NaCl

  Gel matrix washing is essential to remove by-products and excess reactants formed during the synthesis of the active material. The acidity of the gel matrix due to the presence of excess reactants degrades the build material used in this system. The hydrogel is washed at a controlled pH. The gelling pH of the matrix used in the method or the concentration of reactants, temperature, reaction time changes the properties of the active agent such as pore size, porosity, pore volume and surface area.

  The component is further dried under specified conditions to convert the hydrogel to an airgel. The type of silicate, the type of salt, its pH, concentration, temperature and gel aging or processing time can greatly affect gel properties such as pore diameter, pore volume, surface area and adsorption capacity. Has been observed. Other important factors that affect the gel properties are the salt content and surface tension of the liquid medium as it evaporates from the pores of the gel.

  The manufacture of the desiccant-supported honeycomb matrix chemical filter of the present invention comprises the steps of laminating a water glass treated / impregnated glass fiber substrate (with or without carbon or hydrophobic zeolite) in the form / shape of a cylinder or block; Treating the component with one or more water-soluble divalent / trivalent salts or organic or inorganic acids (strong or weak acid) to convert the water glass into an active substance, and then the activity Impregnating the material with various impregnating agents.

  Soak the produced airgel in oxidizer solution, alkaline solution and weak acid solution, or any reactant suitable for removing various concentrations of gaseous contaminants for various soaking times at various temperatures / Impregnate. When the honeycomb is sufficiently impregnated with the solution, the excess impregnated material is discharged, the concentration is readjusted, and stored in another container.

The time required for complete impregnation varies as a function of adsorbent structure, temperature and other factors. The honeycomb material is then placed in an oven and the impregnated material becomes honeycomb silicate aerogel material and / or silicate hydrogel and activated carbon or hydrophobic until the adhering moisture and water have evaporated or are expelled from the mixture Heat until it remains in the pores of the zeolite. Preferably, the drying time of the impregnated honeycomb material is in the range of 50 ° C to 140 ° C. The exposure time during heating will vary depending on the quality and quantity of each substance, the heating efficiency and other factors. After preparation, the honeycomb matrix impregnated with the impregnating agent is stored until ready for use. The impregnation process is described below:
a. Dehydration of macroporous or microporous desiccant-supported honeycomb matrix
b. Impregnation with impregnating agent
c. Drying of the impregnated macroporous or microporous desiccant-supported honeycomb matrix

  In our experiments, preferred impregnants used are potassium permanganate and sodium permanganate, sodium hydroxide or potassium hydroxide, weak acids such as phosphoric acid and reducing agents such as sodium thiosulfate. The filling rate of the impregnating agent depends on various factors such as the kind of the desiccant, the concentration of the impregnating agent, the immersion time, the temperature, and the number of times of dipping.

Impregnation with potassium permanganate and sodium permanganate on a honeycomb matrix supported by a macroporous or microporous desiccant material (with or without activated carbon), 10 ° C to 90 ° C, most preferably At 70 ° C., 5 to 60 minutes, most preferably 15 minutes, in the range of 5% to 40%, preferably 15% for potassium permanganate and 30% for sodium permanganate. Impregnation with potassium manganate / sodium permanganate solution to achieve maximum impregnant loading without affecting the mechanical strength and water / CTC adsorption capacity of the matrix. Table 1 details the percentages of the impregnating agent (KMnO ₄ vs. NaMnO ₄ ) filling factor and the factors that affect the adsorption capacity of the impregnated honeycomb desiccant carrying matrix.

  Concentration, soaking time, solution temperature, continuous dipping and active material surface properties play an important role in simultaneously achieving the desired loading and adsorption amount. Using micropores or macropores and / or hybrid desiccants (insoluble metal silicates and activated carbon acids), alkalis, preferably sodium hydroxide or potassium hydroxide, or acids, preferably phosphoric acid and A method for impregnating with a reducing agent such as sodium thiosulfate will be described below. A slurry of activated carbon is prepared in a water glass solution and the honeycomb matrix is rolled up into a block or cylindrical form. A honeycomb matrix supported by water glass and activated carbon is treated with a salt solution as described above. A honeycomb matrix supported by a desiccant material (with or without activated carbon), whether macroporous or microporous, is impregnated with various concentrations of impregnating agent.

Impregnation with potassium hydroxide 10 ° C to 50 ° C, most preferably, in a honeycomb matrix supported by a desiccant material (with or without activated carbon and / or hydrophobic zeolitic material) macroporous or microporous At 30 ° C., 5 to 60 minutes, most preferably 15 minutes, in the range 2% to 15%, most preferably 6% potassium hydroxide solution impregnated to give mechanical strength and water / CTC adsorption of the matrix A maximum saturant loading is achieved without affecting capacity. Table 2 shows the details of the factors affecting the% filling rate of the impregnating agent (KOH) and the adsorption capacity of the impregnated honeycomb desiccant-carrying matrix.

Phosphoric acid impregnation A honeycomb matrix supported by a macroporous or microporous (with or without activated carbon) material is applied to 10 ° C to 50 ° C, most preferably at 30 ° C for 5 to 60 minutes, most Preferably in the range of 2% to 15% for 15 minutes, most preferably 8% phosphoric acid solution is impregnated to fill the maximum impregnant without affecting the mechanical strength and water / CTC adsorption capacity of the matrix Achieve rate. Table 3 shows the details of the factors affecting the percentage of the impregnating agent (phosphoric acid) filling rate and the adsorption capacity of the impregnated honeycomb desiccant-carrying matrix.

Impregnation with sodium thiosulfate on a honeycomb matrix supported by a macroporous or microporous material (with or without activated carbon or hydrophobic zeolite) at 10 ° C to 50 ° C, most preferably at 30 ° C, Impregnation with 5% to 60 minutes, preferably 15 minutes, 5% to 45%, preferably 15% sodium thiosulfate solution, without affecting the mechanical strength and water / CTC adsorption capacity of the matrix , To achieve maximum impregnant filling rate Table 4 shows the details of the factors that affect the filling rate of the impregnating agent (sodium thiosulfate) and the adsorption capacity of the impregnated honeycomb desiccant-carrying matrix.

The present invention provides several significant advantages over prior art methods. Some of these are summarized below.
1. Macroporous materials are generally preferred, but microporous materials can be impregnated with potassium permanganate to a high loading percentage.
2.There is an increase in the degree of filling rate due to several factors, some of which are listed below:
(a) The substrate GSM is significantly higher than that used in the prior art. GSM is generally in the range of 50 to 150 gsm, preferably in the range of 80 to 120 gsm. This allows for a higher desiccant fill rate for the substrate, resulting in a higher impregnant fill rate.
(b) In situ formation of the desiccant is carried out to a neutral pH and is generally minimally affected by the gas chemistry, whether acidic or basic. Binders are preferably avoided and are not considered necessary for the formation of desiccant preparations, and therefore all the desiccant materials thus obtained are active substances. This ultimately increases the surface density of the substrate from 400 gsm to 750 gsm.
(c) The degree of filling can also be improved by a combination of different factors such as immersion time, temperature and concentration. For example, permanganate (usually Na permanganate) achieves a fill factor of over 30%. Furthermore, since the required moisture content is maintained and synthesized in situ, the desiccant has a higher adsorption capacity, and further advantages include the fact that the desiccant can be bacteriostatic and non-flammable. .
(d) Mixing a hydrophobic desiccant such as carbon powder or a zeolitic material selected from HISIV or ZSM-05 with a suitable binder (preferably inorganic) prior to in situ formation of the desiccant. By preference, the desiccant can be combined with activated carbon or a hydrophobic zeolite. This makes it possible to capture / encapsulate the carbon particles in the desiccant. Thereby, odor control, VOC adsorption, and the structural strength of the matrix itself can be improved.
3. The present invention allows multiple fluid geometries at the expense of matrix surface area, if required, and allows lower pressure drop without significant performance and material sacrifice.
4. Achieves efficiencies up to 100% despite contact time reduction when used at higher surface speeds from 400 fpm to 600 fpm [2 m / sec to 3 m / sec].

Claims (34)

  A desiccant-supported honeycomb chemical filter comprising a matrix formed from a substrate having a desiccant generated in situ or deposited on a substrate, wherein the desiccant is a metal silicate, silica gel, molecular sieve, activated alumina Selected from the group consisting of activated carbon and any mixture thereof, wherein the substrate is further impregnated with one or more of an oxidizing agent, or an alkali metal hydroxide, or a strong or weak acid, or a reducing agent , Chemical filter.   2. The chemical filter according to claim 1, wherein the substrate comprises an inorganic substance or an organic substance or a mixture thereof.   3. A chemical filter according to claim 2, wherein the substance is in the form of fibers or pulp.   4. The chemical filter of claim 3, wherein the inorganic fibers are selected from the group consisting of glass fibers, kraft paper, ceramic paper, and any combination thereof.   5. The chemical filter according to claim 4, wherein the inorganic fiber is a glass fiber.   The desiccant according to claim 1, wherein the desiccant is selected from a combination of metal silicate and silica gel or metal silicate and activated carbon and / or a hydrophobic desiccant such as a zeolite selected from HISIV and ZSM-5. Chemical filter.   The chemical filter of claim 6, wherein the metal silicate is selected from potassium silicate and sodium silicate.   8. The chemical filter of claim 7, wherein the silicate is neutral grade sodium silicate. 9. The chemical filter according to claim 8, wherein the ratio of SiO ₂ to Na ₂ O in the sodium silicate is in the range of 1: 2.0 to 1: 4.0, preferably in the range of 1: 3.   2. The chemical filter of claim 1, wherein the material to be impregnated is selected from the group consisting of potassium permanganate, sodium permanganate, potassium hydroxide, sodium hydroxide, phosphoric acid and sodium thiosulfate.   11. A chemical filter according to claim 10, wherein the filling rate of the substance to be impregnated in the matrix is in the range of 4% to 40%, preferably about 20%.   12. A chemical filter according to any one of the preceding claims, wherein a binder is preferably absent.   13. A chemical filter according to any one of the preceding claims, wherein activated carbon and / or a hydrophobic desiccant material such as HISIV or ZSM-5 is added with the desiccant generated in situ.   14. The chemical filter according to any one of claims 1 to 13, wherein the base weight of the substrate is in the range of 50 gsm to 150 gsm.   15. The chemical filter according to any one of claims 1 to 14, wherein the substrate has a basis weight in the range of 80 gsm to 120 gsm. (i) a step of dehydrating the macroporous or microporous desiccant-supporting honeycomb matrix at a temperature of 100 ° C. or higher;
(ii) A desiccant-carrying step comprising impregnating a suitable impregnating agent into the dehydrated desiccant-carrying honeycomb matrix and then drying the matrix while maintaining a moisture content in the range of 15% to 30%. Manufacturing method of honeycomb chemical filter. (i) treating the substrate material with a desiccant-forming substance or desiccant selected from the group consisting of metal silicates, silica gels, molecular sieves, activated alumina, activated carbon and any mixtures thereof, A process wherein the desiccant-forming substance is in the form of a solution having a concentration ranging from 15% to 40%;
(ii) drying the treated material to reduce its moisture content to a range of 15% to 40%;
(iii) immersing the substrate matrix in a water-soluble metal salt or a strong or weak acid to form a hydrogel to obtain a gel matrix;
(iv) washing the gel matrix obtained in step (iii) to remove excess reactants and unwanted by-products;
(v) drying the gel matrix under controlled temperature and pH conditions to convert the hydrogel to an airgel matrix;
(vi) treating the airgel matrix with one or more of an oxidizing agent, an alkali metal hydroxide, or a strong or weak acid, or a reducing agent;
17. The method of claim 16, comprising drying the treated airgel matrix of step (vi) at a temperature in the range of 50 ° C. to 140 ° C. to obtain the chemical filter.   17. The method of claim 16, wherein the substrate comprises an inorganic or organic material or a mixture thereof.   17. A method according to claim 16, wherein the substance is in the form of fibers or pulp.   20. The method of claim 19, wherein the inorganic fiber is selected from the group consisting of glass fiber, kraft paper, ceramic paper, and any combination thereof.   21. The method of claim 20, wherein the inorganic fiber is a glass fiber.   19. A method according to claim 18, wherein the desiccant is selected from metal silicates and silica gels.   23. The method of claim 22, wherein the metal silicate is a water soluble silicate selected from potassium silicate and sodium silicate.   24. The method of claim 23, wherein the silicate is neutral grade sodium silicate. During the sodium silicate, the ratio Na ₂ O of SiO ₂ is 1: 2.0 to 1: 4.0 by weight, preferably, 1: 3, The method of claim 24.   17. The method of claim 16, wherein the material to be impregnated is selected from the group consisting of potassium permanganate, sodium permanganate, potassium hydroxide, sodium hydroxide, phosphoric acid and sodium thiosulfate.   27. A method according to claim 26, wherein the filling rate of the substance to be impregnated in the substrate is in the range of 4% to 40%, preferably 30%.   28. A method according to any one of claims 16 to 27, wherein a binder is preferably absent.   29. A process according to any one of claims 16 to 28, wherein the activated carbon or hydrophobic zeolite is added with a desiccant generated in situ.   The method according to claim 16, wherein the moisture content of the desiccant-containing matrix is preferably 20%.   18. The method of claim 17, wherein step (vii) is performed at a temperature in the range of 10 ° C to 90 ° C for 5 minutes to 60 minutes.   32. A process according to claim 31, wherein step (vii) is carried out at a temperature of 70 <0> C, preferably for 15 minutes.   16. A chemical filter according to any one of claims 1 to 15 for use in removing contaminants including gases, odorous elements or volatile organic compounds from an air supply stream.   A desiccant wheel-type exchanger comprising the chemical filter according to any one of claims 1 to 15.