MXPA98002225A - Catalytic packaging material for catalytic oxidation regenerat - Google Patents

Abstract

The present invention is concerned. The homogeneous catalytic regenerative heat transfer packing material is made by impregnating the ceramic packing material with a solution of a catalyst precursor and then fixing the precursor in the catalyst form. The catalyzed packing material is suitable for use in a process for the regenerative catalytic oxidation of waste gases, in particular, gases that include volatile organic compounds, carbon monoxide or combinations thereof.

Description

CATALYTIC PACKAGING MATERIAL FOR EGGENERATIVE CATALYTIC OXIDATION DESCRIPTION OF THE INVENTION This invention relates to novel homogenous regenerative catalysed packaging material for the regenerative catalytic oxidation of waste gases such as, but not limited to, volatile organic compounds, carbon monoxide and combinations thereof. A particular embodiment of the invention is a process for making such a catalytic packaging material by impregnating the porous regenerative heat transfer packaging material with a solution of a catalyst precursor, and then fixing the precursor in the catalyst form. Air pollutants, such as volatile organic compounds (VOCs), carbon monoxide (CO) and nitrogen oxides (NOx), are often industrially controlled by an incineration system that uses either a catalytic or thermal process. The control of COV and CO emissions is achieved by initiation oxidation reactions in these systems that convert contaminants into safe water and C02. Nox control is often achieved by a selective reduction reaction which reacts ammonia with Nox to form N2 and water. The reduction system is typically installed downstream of an industrial process to remove contaminating constituents in the flow gas before the gas is emitted into the atmosphere. The thermal process depends on the homogeneous gas phase reactions for the destruction of these compounds, and operates normally at about 1500 to 1800 ° F (800 to 1000 ° C) with a residence time of about 1 second. On the other hand, destruction reactions for catalytic processes occur on the surface of the catalyst rather than in the gas phase. The catalytic processes typically operate at approximately 600 to 1000 ° F (300-550 ° C) with a residence time of approximately 0.1 seconds or less. Catalytic incineration systems are typically smaller in size, and consume less fuel than non-catalytic thermal systems. Commercially, there are two general types of incineration, regenerative and recuperative designs, for either thermal or catalytic processes. Regenerative thermal oxidation (OTR) or regenerative catalytic oxidation (OCR) systems have a very high thermal efficiency (> 90%). The recuperative thermal or catalytic oxidants typically have a heat recovery of no more than 70%. The selection of the regenerative or recuperative type of the oxidants depends mainly on the exit concentrations and the outflows, which also affects the capital and operating costs of the reduction system. A detailed discussion of the VOC control methods, which include thermal oxidation and regenerative and recuperative catalytic oxidation, is indicated in Ruddy, et al., "Select the Best COV Control Strategy", Chemical Engineerins Prosress. July 1993, p. 28-35, incorporated herein for reference. A typical regenerative thermal oxidation system is described in U.S. Pat. No. 3,870,474, incorporated herein by reference. In such a process, VOCs and CO in a gaseous stream are incinerated at a relatively high temperature of approximately 1500 ° F (800 ° C). Before entering the combustion zone, the gas stream passes through a first packed column of the heat transfer packaging material which heats the gas, and then exits through an identical second packed column which is heated by the gas in the combustion zone. In this way the hot gas leaving the combustion zone passes through a packed column, heating the packaging material therein. Then the gas flow is reversed, and the incoming gas is heated as it passes through the packed column. By the use of such regenerative processes, the efficiency of thermal incineration has been greatly increased. A disadvantage of such thermal oxidation systems is that they require heating the gas stream to a relatively high temperature of about 1500 ° F (815.5 ° C). Patent 3,870,474, indicates, in column 6, lines 3-7, that a suitable combustion catalyst can be placed in the hottest part of the regenerators for proCOVar that the contaminants in the air are oxidized at a lower temperature. The heat transfer packaging materials are conventionally made of inorganic metals or metal oxides. See Perry Chemical Engineer's Manual, fifth edition, 1973, chapter 18, in gas-liquid contact. Figure 18-35 illustrates typical packaging such as Raschig rings, Lessing rings, Berl chairs, Intalox chairs, Tellerette rings and Pall. Ceramic packaging can be of almost any type, including balls, rings or chairs. Packings are also available in a variety of different sizes. The packings of smaller size have a higher efficiency of heat transfer due to the larger geometric surface they have per unit volume of the reactor, but also to a greater pressure drop. The optimum packing size and reactor dimensions are chosen to meet the requirements of auxiliary system components, such as blowers, fans, duct dimensions, etc. A great advantage to using catalysts made from heat transfer packaging materials is that the same catalyst bed is also an effective source of heat storage for regenerative heat transfer. In this way, the regenerative systems incorporating these catalyst materials will inherently have reduced total bed dimensions than those systems that use catalysts of deficient heat transfer / storage materials. Additionally, the conformations of the heat transfer packaging materials are all optimized to provide a low pressure drop, and high heat transfer efficiency. These same properties are a key catalytic surface characteristic for achieving high mass transfer efficiency to catalytically oxidize VOC emissions with minimal pressure loss. These unique characteristics make the use of heat transfer packaging materials as carriers of highly desirable catalysts for regenerative catalytic oxidants. In a regenerative bed, the heat transfer packaging materials are typically randomly deposited in the container. The packing materials are normally required to have sufficient physical strength to retain the bed weight for the particular packing and container involved. This physical strength is generally indicated by the compressive strength of the packing, which can be measured by placing a sample of the packing on a standard compression test device, and measuring the force necessary to break the packing at its weakest orientation. Additionally, these packing materials need very high cohesive strength to resist erosion that can be caused by interparticle abrasion, loading and unloading, etc., and adhesive strength to retain the catalyst bond to the surface. For catalyzed heat transfer packaging, erosion resistance is particularly important since erosion is a likely key cause for the deactivation of catalyst efficiency. European Patent Application No. 629432, published on December 12, 1994, discloses a heat transfer packaging material with the catalyst and / or absorbent on its surface for use in a regenerative incineration process. In this publication, the catalyst is applied as a wash coating in suspension to the exterior of the low porosity heat transfer packing, such as ceramic chairs. As described in the publication, the catalyst ingredients in such wash coatings are supported on inorganic oxide powders of high surface area which in turn are deposited on the surface of the ceramic substrates. However, it has been found that suspension washing coatings adhere poorly to heat transfer packaging materials, typically ceramic substrates. Under normal operating conditions, these catalyst coated materials in suspension are prone to deactivation due to wear. Another known method for placing catalysts on any support is by solution impregnation, in which the catalysts are impregnated from a solution in the pores of the support material. However, most of the existing heat transfer packaging materials have not required the surface properties to allow such impregnation and provide high catalytic activity. The key reason is that commercial packaging materials are usually very dense, and lack the necessary icrostructure to allow impregnation of the solution. This is due, in part, to the need for high physical strength of such packaging materials. To obtain such strength, the packaging materials are typically precalcined at elevated temperatures which results in loss of porosity and collapse of the micro structure of the surface area. As a result, a high strength physical catalyst combined with high catalytic activity has not been commercially available. In accordance with the present invention, it has been discovered that high strength, high activity catalyst can be manufactured using packaging materials with micro desirable surface structure, as measured by the minimum values of BET surface area and porosity. The BET surface area impacts the activity of the catalyst, and the porosity impacts the ability to impregnate catalytic ingredients on the catalyst. The catalysts are heat transfer packaging materials impregnated with catalysts that incorporate high catalytic activity and high surface resistance suitable for catalytic reactions. In the method of the present invention, the catalyst ingredients are embedded in the heat transfer packaging materials to form the "homogeneous" catalyst material. This is in contrast to the previously known compound forms where the catalyst adheres in segregated layers coated on the outer side of the packaging materials. The homogeneous regenerative catalytic oxidation (OCR) catalysts of the present invention have the necessary physical and catalytic properties suitable for regenerative catalytic oxidants.

It should be noted that for purposes of the present invention, the catalytic material does not have to be evenly distributed across the substrate to be considered "homogeneous". It is sufficient that the catalytic material has been sufficiently absorbed in the porous ceramic substrate in such a way that at least some of the catalytic material is dispersed throughout the volume of the substrate material. This is a marked distinction for a wash coating of a suspension of the catalytic material on the outer side of a non-porous substrate. The homogeneous catalyst is prepared by impregnating the substrate of the porous ceramic packing material with a solution of a soluble catalyst precursor in the catalyst form. The catalyst precursor is then fixed to an active catalyst by reducing, oxidizing or in some other way reacting the soluble catalyst precursor to change it to its active catalytic form. In the case of noble metals, the active catalytic form is generally elemental metal, while in the case of basic metal catalysts, the catalytic form is generally basic metal oxide. The substrate with the absorbed solution is dried and calcined to leave the catalytically active material on the surface of the packaging material as well as dispersed throughout the material, and remove the solvent and organic residue.

The porous ceramic packing material should have a minimum porosity of about 0.05 cm 3 / g and a BET surface area of at least about 4 m 3 / g. The minimum porosity is desirable to ensure adequate absorption of the catalyst precursor solution. It has been found that the minimum surface area is desirable to provide a desired level of catalytic activity. However, for particular substrates, catalysts and catalytic processes, lower levels of porosity and surface area may be acceptable. Catalyst ingredients include, but are not limited to, noble metals, such as Pt, Pd, Rh, Ir, Re, and basic metal oxides, such as Mn02, Cr203, Ce02, CuO, V205, 03. The solution may be a aqueous or non-aqueous solution (organic solvent). Any desired catalyst compound can be used with the proviso that the compound is soluble in the chosen solvent and can be attached to a desired metal or metal oxide after heating in the air at elevated temperatures, or after being subjected to a process Chemical fixation The substrate material can be any porous ceramic material which is capable of acting as a heat transfer packing. It is desirable that the substrate material be inert to the catalyst components and to the gas to which they are exposed. Examples of suitable ceramic materials include alumina, sillimanite, petalite, cordierite, mulita, ziOCRn, zyOCRm mulita, spodumene, titania, alumina titanate, etc. A preferred substrate material is alumina, either in substantially pure form, or as a component of a naturally occurring mineral such as bauxite. A particularly preferred substrate comprises alumina range. In order to be catalytically active, the material must have at least the previous values of porosity and BET surface area for the supports. The homogeneous catalytic packing material of the present invention can be used in a regenerative catalytic oxidation process. In such an OCR process, a gaseous stream containing oxygen and waste gases, such as volatile organic compounds (VOCs), carbon monoxide or combinations thereof, is passed over and in contact with the catalytic packing material under conditions of operation which promote the oxidation of waste gases to C02 and water. Such operating conditions include the ratio of temperature and gas flow, and depends, among other things, on the particular catalyst and the gas to be treated. The proper operating conditions can easily be determined by someone skilled in the art. The regenerative catalytic oxidation (OCR) process of the present invention can also be carried out by modifying a non-catalytic regenerative thermal oxidation (OTR) process. In such a case, a portion of the non-catalytic OTR packing is replaced by the OCR packing of the present invention, or the OCR packing is added to the existing OTR packing. Preferably, the OCR packing is replaced or added as a layer at the hottest point in the packaging tower, which is generally at the point where the gas enters the tower after combustion. It is at this point in the process that catalyzed packing is most useful to promote the oxidation of waste gases. Additionally, if the OCR packaging is maintained as a separate layer, then the OCR and OTR packaging materials can be replaced or recycled independently. This allows the independent selection of the best packaging materials for the OCR and OTR processes. That is, the OTR packaging material does not have to meet the porosity, surface area and other packaging requirements which is used in the OCR packaging material. In this way the packaging material with optimum thermal properties and others can be used as the packaging material of OTR, although such packing may not be suitable for use in the formation of OCR packaging by the process of the present invention. . In addition, the OCR and OTR packaging materials may not have to be revised in the same period. In addition savings can be produced since the catalyst containing OCR is generally more expensive than the OTR catalyst. The ceramic packing material can be impregnated with an aqueous solution of the catalyst precursor by any suitable means, as is well known in the art. A simple method for applying the precursor solution is to immerse the packaging substrates directly into the solution. However, although good results can be obtained using the simple method, it has been found that simple immersion techniques require an excess of catalyst solution, and can result in varying levels of catalyst deposition. The use of the excess catalyst solution may not be a problem when a basic metal catalyst is used, but can greatly increase the production cost when the precious metal catalyst is used. A preferred method for applying the catalyst solution to the ceramic substrate is by an incipient wet application process, as discussed, for example, in U.S. Patent No. 4,134,860, incorporated herein by reference. The point of incipient humidity is the point at which the amount of liquid added is the lowest concentration at which the substrate is sufficiently dry to absorb essentially all of the liquid. In this form the substrate can be coated with an aqueous solution of a relatively expensive soluble catalyst salt, such as a platinum solution, using only as much solution as is absorbed in the porous substrate. Additionally, when the incipient wet method is used, the amount of the catalyst applied to the substrate can be controlled accurately and consistently. When noble metals are used as catalyst components, the noble metals are impregnated with the solution in the porous substrate. The solution comprises a soluble form of the noble metal in a suitable solvent. For purposes of this application, the soluble form of the noble metal catalyst is referred to as the "catalyst precursor", while the active elemental form is referred to as the "catalyst". Such noble metals include, but are not limited to, metals of the platinum group (platinum, palladium, rhodium, iridium, osmium and ruthenium) as well as other noble metals including ruthenium, gold and the like. The impregnation can be carried out by techniques well known to those of ordinary skill in the art. The solvent is then separated, generally by drying, and the soluble noble metal compound is fixed to its catalytic active form by reducing the elemental metal. Methods for reducing the noble metal compound to elemental metal include calcination at elevated temperature in the air, or using a chemical reactant, such as an acid, to form the elemental metal. For the method of the present invention, the chemical process is preferred since it generally reduces the calcination temperature necessary to obtain the product impregnated with the final elemental metal. Good results have been obtained first by drying the impregnated substrate, submerging the substrate in acid, such as acetic acid, and then drying and calcining further at mild temperatures to remove the solvent and residual organic material. The material can be dispersed in the substrate by impregnating the material with a solution containing a compound of the desired platinum group metals. The solution can be an aqueous or non-aqueous solution (organic solvent). Any metallic compound of the platinum group can be used with the proviso that the compound is soluble in the chosen solvent and decomposes to the metal after heating in air at elevated temperatures. Illustrative of these metal compounds of the platinum group are chloroplatinic acid, ammonium chloroplatinate, bromoplatinic acid, hydrated platinum tetrachloride, dichlorocarbonyl platinum dichloride, dinitrodiaminplatinum, amine-solubilized platinum hydroxide, rhodium tichloride, hexaaminerodium chloride, rhodium carbonyl chloride , hydrous rhodium trichloride, rhodium nitrate, rhodium acetate, chloropalladic acid, palladium chloride, palladium nitrate, diaminpalladium hydroxide and tetraaminpalladium chloride. When base metal catalysts are used, the impregnation process is essentially the same as for platinum group metals, except that the final catalytic material is the basic metal oxide. As above, the "catalyst precursor" is in a soluble form of the basic metal, which is dissolved in a suitable solvent, while the "catalyst" is the basic metal oxide. Such base metals include manganese, chromium, cerium, copper, vanadium, and tungsten, as well as many others which have been identified in the art. A solution of the basic metal is impregnated in the packing, and then the solvent is separated, typically by drying. The catalyst precursor is then fixed to a catalyst either by calcination in the air or by chemical reaction. Soluble forms of base metals are well known in the art. For example, suitable manganese oxide precursors include solutions of manganese nitrate, manganese acetate, manganese dichloride or manganese dibromide. In a similar manner, to produce ceria (cerium oxide) or cobalt oxide catalysts, soluble cobalt or cerium compounds such as cerium nitrate, cerium acetate, cerium sulfate or cerium chloride, and cobalt nitrate, Cobalt chloride or cobalt bromide can be used. Particularly good results have been obtained using an aqueous solution of cerium nitrate as the catalyst precursor to form ceria catalyst. (cerium oxide) and using cobalt nitrate to form the cobalt oxide catalyst. The impregnation of the substrate with the solution of the metal compound can be carried out in forms well known in the art. A convenient method is to place the substrate material in a rotary evaporator which is partially submerged in a heating bath. The impregnation solution which contains a quantity of the desired metal compound to provide the desired concentration of the oxide or metal in the finished catalyst is now added to the substrate and the mixture is cold-rolled (not heat) for a time of about 10 to 60 minutes. Then, heat is applied and the solvent is evaporated. This usually takes from about 1 to about 4 hours. In this step, the catalyst material is preferably fixed to noble metal or basic metal oxide forms by chemical reactions. Finally, the coated substrate is removed from the rotary evaporator and calcined in the air to remove the solvent and residual organics, and to fix the catalyst if it has not previously been fixed by chemical means. Typically, the calcination is at a temperature of about 300 ° C-600 ° C for about 1 to 3 hours. When the chemical fixation is used, the calcination temperature is preferably about 300-450 ° C. When calcination is also being used to fix the catalytic metal, then temperatures of about 500-600 ° C are used. Since calcination at higher temperatures can reduce the BET surface area of the final product, it is desirable to use a chemical fixation method which allows calcination at lower temperatures. As discussed above, a preferred method for applying a precious metal solution to the substrate is by an incipient wet method. In this process, the substrate of the packaging material is placed in a planetary mixer and the impregnation solution is added under continuous stirring until the state of incipient humidity is achieved. The substrate is then dried to remove the solvent. For aqueous solutions, drying is typically in an oven for 4-8 hours, followed by calcination at about 300 ° C-600 ° C for about 1-3 hours, as discussed above. The substrate of the packaging material of the present invention can be in any configuration, shape or size which exposes it to the gas to be treated. For example, the material of the substrate can be formed into conformations such as tablets, pellets, granules, rings, spheres, chairs, etc. It has been found that the chairs are particularly suitable for use in OCR systems. The substrate material can be any porous ceramic material which is capable of acting as a heat transfer packing. It is desirable that the substrate material is not reactive with the catalyst components and is not degraded by the gas to which it is exposed. Examples of suitable ceramic materials include alumina, sillimanite, petalite, cordierite, mulita, ziOCRn, ciOCRn mullite, spodumene, titania, alumina titanate, etc. A preferred substrate material is alumina, either substantially in pure form, or as a component of a naturally occurring mineral such as bauxite. As discussed above, in a regenerative bed, the heat transfer packaging materials are typically randomly deposited in the container. It is required that the packaging materials have sufficient physical strength to retain the bed weight for the particular packaging and container involved. This physical strength is generally indicated by the resistance to the compression of the packing, which can be measured by placing a sample of the packing in a standard compression test device, and measuring the force necessary to break the packing in its weakest orientation. For each one-inch (2.54 cm) chair-shaped packaging, a compressive strength of at least about 50 pounds (22.68 kg), preferably at least about 100 pounds (45.36 kg) is desirable. Additionally, these packing materials need a very high cohesive strength to resist erosion that can be caused by interparticle abrasion, loading and unloading, etc., and adhesive strength to retain the catalyst bound to the surface. For catalyzed heat transfer packings, erosion resistance is particularly important as erosion is a likely key cause for the deactivation of catalyst efficiency. A simple test of cohesive strength is by adhering the packaging material with a finger, or some suitable material, and observing if any ceramics are detached from the surface as dust. Such dust formation is an indication of poor cohesion. EXAMPLE 1 In this example, 5/8 inch (1.59 cm) bauxite balls are used as the substrate for the packaging material and platinum as the catalyst. The bauxite balls have a density of 47 lb / ft3 (753.33 kg / m3), a surface area of 150-180 m2 / g, and a water absorption of 5-10%, by weight. The solution of the platinum catalyst precursor in this and all the examples is an 18% aqueous Platinum A solution, which is a solution of aqueous platinum hydroxide solubilized in amine (H2Pt (OH) 6) containing 18% in Platinum weight, commercially available from Engelhard Corporation. The balls are immersed in the platinum solution for 20 minutes. The balls are dried in air, then dried at 150 ° C for 2 hours, and calcined at 500 ° C for 2 hours. It is found that the final catalytic packing material contains 0.36% platinum, by weight. The examples are also prepared using the same bauxite ball substrate, and ceria (cerium oxide) and cobalt oxide as the catalysts. In one example, the balls are immersed in a solution of aqueous cerium nitrate, and dried and calcined as above. It is found that the final catalytic packing material contains about 5% ceria (cerium oxide), by weight. In another example, the balls are immersed in a solution of cobalt nitrate, and dried and calcined as above. It is found that the final catalytic packing material contains approximately 5% cobalt oxide, by weight. EXAMPLE 2 In this example, one inch (2.54 cm) bauxite chairs are used instead of bauxite balls. The chairs have a density of 47 lb / ft3 (753.33 kg / m3), a surface area of 150 m / g, and a water absorption of 10-15%, by weight. The chairs are immersed in the platinum solution at 75 ° C overnight. The chairs are then air dried, then dried at 150 ° C for two hours, and calcined at 500 ° C for two hours. It is found that the final catalyst contains 0.06% platinum, by weight. EXAMPLE 3 In this example, one-inch (2.54 cm) alumina chairs are used instead of bauxite balls. The chairs have a density of 37 lb / ft3 (593.05 kg / m3), a surface area of 10 m2 / g, and a water absorption of 22%, by weight. The chairs are immersed in the platinum solution at 95 ° C overnight. The sodium formate is then added to the solution to fix the platinum in the chairs. The chairs are then air dried, then dried at 150 ° C for two hours, and calcined at 500 ° C for two hours. It is found that the final catalyst contains 0.04% platinum, by weight. EXAMPLE 4 A test is created to measure the abrasion resistance of the packaging materials. The procedure of the adhesion test is to load packaging materials, in this case all the chair size of one inch (2.54 cm), to occupy approximately 50% of a plastic container of 4 inches (10.16 cm) in diameter by 6 inches (15.24 cm) in length. Except that the test sample chairs, and all the other chairs in the package are Inalox (Koch Flexisaddle ™) chairs. This container is then placed on a double laminator fixed to rotate at a speed of 60 revolutions per minute. After one hour of rotation, the weight loss of the sample packaging material is measured. This weight loss is an indication of the ability of the packaging materials to resist the abrasion that will occur from interparticle erosion in current use. A pattern of less than less than about 20% by weight of the catalytic material is necessary in order to pass the abrasion test. EXAMPLE 5 (Comparative) Catalyzed washing coating materials are formulated by preparing alumina suspensions, which have a BET surface area of 150 m / g, in which the alumina is pre-impregnated with Pt. The solid content in the suspension is typically 30 to 45%. Binders such as colloidal Si02 or Zr02 solutions (up to 10%) are also added to some suspensions for the purpose of improving adhesion. Ceramic chairs are submerged in these suspensions for Pt / alumina wash coating on the ceramic chairs. The normal wash coating load is 50 to 150 mg per square inch of the volume of the chair. The coated packaging materials are then air dried and calcined at 500 ° C for one hour. These chairs are then subjected to the abrasion test procedure given in Example 4. The results show that all washing coatings chairs, with or without added binders, fail to pass the previous adhesion tests. After the abrasion test, all the layers with washing coatings are essentially separated from their ceramic chairs. Some ceramic chairs are sandblasted and acid etched to increase surface roughness. These chairs are then coated with Pt / alumina suspensions. After subjecting them to the previous adhesion tests, the catalyst wash coatings again fail to adhere to these rough chairs. EXAMPLE 6 (comparative) Stoneware ceramic chair packings (Flexisaddle ™) with the physical properties of less than 2 m2 / g BET surface area and a porosity of 0.1 to 3% are directly immersed in a platinum solution then they are dried at 150 ° C for 2 hours, and calcined at 500 ° C for 2 hours. The loading of the Pt is approximately 6 g / ft3 (212 g / m3). These chairs are then subjected to the abrasion test described in Example 4. These catalyzed chairs show very little loss in abrasion, less than 1%. The activity and durability tests for these catalyzed chairs are made by measuring the conversion of CO between these chairs after they are broken to a size of < l / 4 inches (< 0.64 cm). The activity tests are performed at 20,000 hr "1 of volumetric space velocity, 250 ppm of CO in air and 300 ° C of temperature.The durability tests are determined by aging the catalyst at 550 ° C in the presence of 10% water in air for 16 hours followed by an activity test Even though this catalyst gives reasonably good fresh activity, 80 to 90% CO conversion, the catalyst is severely deactivated, below less than 6% CO conversion after the aging of durability, hence the packaging of the low BET catalyst, low porosity materials do not provide satisfactory catalytic activity EXAMPLE 7 (comparative) The packing of stoneware (Flexisaddle ™) chairs as used in the Example 6 is first leached with a 10% alkaline solution (NaOH) followed by washing with nitric acid.This stage is done to remove possible residual impurities after drying. r for 300 ° c for 1 hour, the leached chairs are then impregnated with Pt following the same procedure given in the Example 6 to give a Pt load of about 6 g / ft3 (212 g / m3). The activity tests on this example also show rapid conversion loss, from 90% fresh below 8% CO conversion after aging. The results shown in Examples 6 and 7 show that the loss of activity after aging is due to the low BET area and low porosity, and not due to the effects of contamination. EXAMPLE 8 A total of 1755 grams of bauxite powder of mesh -200 is mixed dry which is naturally found with 945 grams of florinated kaolin EPK and 176 grams of organic binder, which is a mixture of polyethylene oxide and hydroxymethylcellulose from Dow Chemical Company. Mixing is done in a mixer of the sigma paddle type. An aqueous solution of deionized water is prepared: diethanolamine: silica solution in proportions of 85: 3.5: 1, respectively. A total of 967 grams of this solution is added to the dry mix. Mixing is continued until an extrudable paste is formed. The paste is extruded using a piston extruder and a mold which produces a 15 mm profile of space chair. The extruded chair profiles are cut and formed in the chair shape in its wet stage using a crescent-shaped mold with an outline of the negative of the chair profile. The chairs are then air dried and burned at 1200 ° C. EXAMPLE 9 A total of 1755 grams of bauxite powder of alumina trihydrate -200 mesh which is naturally found with 945 grams of Florid Kaolin EPK and 176 grams of organic binder, which is a mixture of polyethylene oxide, is dry mixed. and hydroxymethylcellulose from Dow Chemical Company. Mixing is done in a mixer of the sigma paddle type. An aqueous solution of deionized water is prepared: diethanolamine: silica solution in proportions of 85: 3.5: 1, respectively. A total of 967 grams of this solution is added to the dry mix. Mixing is continued until an extrudable paste is formed. The paste is extruded using a piston extruder and a mold which produces a 15 mm profile of space chair. The extruded chair profiles are cut and shaped in the chair conformation in their wet stage using a crescent shaped mold with an outline of the negative of the chair profile. The chairs are then air dried and burned at 1200 ° C. It is found that the products produced by this method have BET surface areas in the range of 6-10m2 / g. EXAMPLE 1Q Bauxite mixtures with Al (OH) 3 are extruded with clay materials (Tenneesse M & D clay or EPK clay) to form chairs followed by burning at different temperatures. As soon as the burning temperature is increased, the resistance of the chair becomes greater, and the skin becomes harder to detach it as dust with a finger. However, as soon as the temperature increases, the BET area decreases. Chairs made of 50% bauxite and 50% M &D clay are measures for BET area loss from 94 m2 / g to 500 ° C, to 87 m2 / g to 650 ° C, and to 67 m2 / g to 740 ° C calcination temperature. All these chairs have approximately 15 to 30% porosity. After calcination at 740 ° C, the chairs do not have adequate cohesiveness to survive polishing as indicated in Example 4. These chairs can be made to comply with the adhesion test, but the calcination temperature has to be increased to 1050 ° C or more. The BET surface areas of these chairs are well above the preferred minimum of 4 m2 / g, but typically below about 30 m / g. EXAMPLE 11 The homogeneous regenerative catalytic oxidants can be produced using boehmite of high surface area based on aluminum oxides, as opposed to gibbsite based on aluminum hydroxides, such as bauxite and mono alumina, or trihydrate. Boehmite type of aluminas includes range, delta, teta and any other form of alumina which is produced by treating the boehmites with heat. For catalytic application, the preferred form of boehmite based on alumina series is the alumina range with high surface area. The alumina range loses its surface area with heat treatment. Also, this is transformed, at least partially, into high temperature phases, such as teta or delta alumina. When the homogeneous OCR-based alumina range is heat treated at elevated temperatures, such as 1000 ° C and more, it can retain more of its original surface area than that of the alumina-based gibs described in the previous examples. This depends on the nature of the stabilizers that are added to the alumina range. EXAMPLE 12 The chairs according to Examples 8, 9 and 10 are impregnated with Pt to control the Pt load of 4 to 8 g / ft3 of the volume of the chair. Durability and activity tests are performed under the conditions given in Examples 4 and 6 for these chairs. The results presented in Table 1 show that chairs impregnated with the Pt catalyst having a BET surface area of 6 m2 / g or more and a porosity of 18% or more all maintaining high CO activities. The last column shows the results of abrasion tests according to the test procedure of Example 4. However, chairs which fail the abrasion test may still be suitable for some uses that do not require high resistance to abrasion. Table 1 Ex. Do not . Area BET Conversion Conversion FraVg test) fresh aged abrasion 9 6 95 +% 95 +% Good 9 8 95 +% 95 +% Good 9 10 95 +% 95 +% Good 10 67 95 +% 95 +% Fault 10 87 95 +% 95 +% Fault 8 100 95 +% 95 +% Fault 8 150 95 +% 95 +% failure EXAMPLE 13 In this example, the chairs described in Example 9 are impregnated with catalyst by the incipient wet method.

The solution A of platinum in an amount equal to 22% of the weight of the chair is dispersed on the chairs while they are polished until the platinum solution is absorbed. It should be noted that the cohesive strength of the chairs is important to prevent damage during such coating operations. The coating chairs are then air dried and calcined at 500 ° C for 2 hours. Alternatively, the impregnated chairs can be air-dried, followed by spraying with an acid solution, such as acetic acid, to fix the platinum in elemental form, and then also air-dried and calcined at 400 ° C for 1 hour. As discussed at the beginning, calcining can reduce the BET surface area, and reducing the calcination temperature can therefore improve, ie increase, the BET surface area. The activity results of chairs impregnated in incipient humidity are the same as those reported in Example 12.

Claims (31)

1. CLAIMS 1. A method for making homogeneous catalytic regenerative heat transfer packing material, the method characterized in that it comprises the steps of impregnating a substrate of porous ceramic packing material with a solution of a catalyst precursor and then fixing the precursor of the catalyst. catalyst in the catalyst.
2. 2. The method according to claim 1 characterized in that the substrate of the packaging material has a minimum porosity of about 0.05 cm3 / g and a BET surface area of at least about 4 m2 / g.
3. 3. The method according to claim 1, characterized in that the catalyst comprises a noble metal or a basic metal oxide, and the catalyst precursor is a soluble compound of such noble or basic metal.
4. 4. The method according to claim 3 characterized in that the catalyst is a metal of the platinum group.
5. 5. The method according to claim 1 characterized in that the substrate of the packaging material is in the form of chairs, balls, pills or rings.
6. 6. The method according to claim 1 characterized in that the catalyst solution is an aqueous solution.
7. The method according to claim 1 characterized in that the fixing step comprises calcining the substrate of the impregnated packaging material.
8. 8. The method according to claim 7, characterized in that the calcination is carried out at a temperature of approximately 400 ° C to 600 ° C.
9. The method according to claim 1, characterized in that the fixing step comprises chemically treating the catalyst precursor in the substrate of the impregnated packaging material to form the catalyst, followed by calcination.
10. 10. The method according to claim 9, characterized in that the chemical treatment comprises treating the substrate of the packaging material impregnated with an acid solution.
11. 11. The method according to claim 10, characterized in that the acid solution is a solution of acetic acid.
12. 12. The method according to claim 9 characterized in that the calcination is carried out at a temperature of about 400 ° C to 450 ° C.
13. 13. The method according to claim 1 characterized in that the substrate of the packaging material is formed of a ceramic selected from the group consisting of alumina, bauxite, sillimanite, petalite, cordierite, mulita, ziOCRn, ziOCRn mulita, spodumene, titania ( titanium oxide) and alumina titanate.
14. 14. The method according to claim 13 characterized in that the ceramic comprises alumina or bauxite.
15. 15. The method according to claim 14 characterized in that the ceramic comprises alumina range.
16. 16. The method according to claim 1, characterized in that the impregnation step comprises immersing the substrate of the packaging material in the solution of the catalyst precursor.
17. 17. The method according to claim 1, characterized in that the impregnation step comprises an application process in incipient humidity.
18. 18. The method according to claim 17, characterized in that the catalyst comprises a noble metal.
19. 19. A homogeneous catalytic regenerative heat transfer packaging material characterized in that it comprises a substrate of porous ceramic packaging material impregnated with one or more catalysts of noble metal or basic metal oxide or combinations thereof.
20. 20. The catalytic packaging material according to claim 19, characterized in that the substrate of the packaging material has a minimum porosity of about 0.05 cm3 / g and a BET surface area of at least about 4 m2 / g.
21. 21. The catalytic packaging material according to claim 19, characterized in that the catalyst comprises one or more metals of the platinum group.
22. 22. The catalytic packaging material according to claim 19 characterized in that the substrate of the packaging material is in the form of chairs, balls, pills or rings.
23. 23. The catalytic packaging material according to claim 19, characterized in that the substrate of the packaging material is formed of a ceramic selected from the group consisting of alumina, bauxite, sillimanite, petalite, cordierite, mulita, ziOCRn, ziOCRn mulita, spodumene , titania (titanium oxide) and alumina titanate.
24. 24. The catalytic packaging material according to claim 23, characterized in that the ceramic comprises alumina or bauxite.
25. 25. The catalytic packing material according to claim 24 characterized in that the ceramic comprises alumina range.
26. 26. A homogeneous catalytic regenerative heat transfer packing material made by a method characterized in that it comprises the steps of impregnating a substrate of porous ceramic packing material with a solution of a catalyst precursor and then fixing the catalyst precursor to the catalyst. catalyst.
27. 27. A regenerative catalytic oxidation process characterized in that it comprises passing a gaseous stream containing oxygen and waste gases selected from the group of volatile organic compounds, carbon monoxide and combinations thereof on the homogeneous catalytic regenerative heat transfer packing material. under operating conditions which promote the oxidation of waste gases.
28. The process according to claim 27, characterized in that the homogeneous catalytic regenerative heat transfer packing material comprises a substrate of porous ceramic packing material impregnated with one or more catalysts of noble metal or basic metal oxide or combinations of the same.
29. 29. The process according to claim 27 wherein the homogeneous catalytic regenerative heat transfer packaging material is made by a method characterized in that it comprises the steps of impregnating a substrate of the porous ceramic packing material with a solution of a catalyst precursor and then fixing the catalyst precursor in the catalyst.
30. 30. The process in accordance with the claim 27 characterized in that it further comprises passing the gaseous stream over the non-catalytic regenerative heat transfer packing material.
31. 31. The process in accordance with the claim Characterized in that the catalytic and non-catalytic regenerative heat transfer packaging materials are in different layers.