Abstract:
The present invention provides a method and system for combined conversion of ozone and organic compounds in airplane bleed air. Catalytic converters have previously been used to reduce the levels of ozone in airplane bleed air. However, these converters have not yet provided an efficient system and method for effectively and simultaneously removing both ozone and organic compounds (including hydrocarbons). The present invention accomplishes the goals of removing both harmful substances by providing a washcoat on a single anodized surface layer, wherein the washcoat may contain an active metal oxide which is active for ozone conversion and may be impregnated with an active metal which is active for hydrocarbon and carbon monoxide conversion. Thus, a single system is disclosed that destroys both ozone and hydrocarbons.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention generally relates to catalytic converters for reducing the level of pollutants and, more specifically, to a converter for an airplane bleed air system.  
           [0002]    Environmental control systems for aircraft supply pressurized and conditioned air to the aircraft cabin. The temperature, pressure, and relative humidity must be controlled to provide for the comfort of flight crew and passengers within the aircraft. Typically, environmental control systems receive compressed air, such as bleed air from a compressor stage of an aircraft gas turbine engine, expand the compressed air in a cooling turbine, and remove moisture from the compressed air through a water extractor.  
           [0003]    Toxic ozone in the compressed air can become an issue when aircraft cruise at altitudes that exceed 20,000 feet. Modern jet aircraft are typically designed for fuel-efficient operation at relatively high altitudes of 25,000 feet or more above sea level. At these altitudes, the ozone content in ambient air is relatively high and, thus, the air supplied to the aircraft environmental control system can contain a substantial amount of ozone. Air containing ozone can cause lung and eye irritation, headaches, fatigue, and breathing discomfort. Because of these dangers, the Federal Aviation Administration (FAA) requires that ozone levels in airplane cabin air be maintained below specified limits.  
           [0004]    It is known within the art to utilize catalytic converters to reduce or eliminate ozone in the air supplied to the aircraft cabin. There are a number of desirable characteristics for an ozone destroying catalytic converter of an aircraft. These characteristics include a) high efficiency of ozone conversion at bleed air operating temperature; b) good poison resistance from humidity, sulfur compounds, oil, dust, and the like, which may be present in the compressed air (for long life and minimum system overhaul and maintenance costs); c) light weight to minimize system parasitic load; d) high structural integrity of catalyst support under extreme heat or vibration shock, which may arise during normal flight conditions (also for long life and minimum system overhaul and maintenance costs); and e) high mass transport efficiency with low pressure drop.  
           [0005]    Known within the art are ceramic monolith supports which carry a catalyst on a washcoat applied to their surfaces. For example, U.S. Pat. No. 4,405,507 discloses aluminum honeycomb treated with NaOH. U.S. Pat. No. 5,145,822 discloses catalysts attached by an elastic organic adhesive to a metal foil support. U.S. Pat. No. 6,203,771 discloses a catalytic converter with active metals supported directly on an anodized surface layer to remove ozone. However, none disclose the use of the washcoat to destroy ozone, combined with an active metal to remove hydrocarbons.  
           [0006]    While it is required that ozone be removed from the airplane bleed air, it is not yet required that hydrocarbons be removed. In the descriptions below, the term hydrocarbons may be taken to include aviation lubricant fumes, hydraulic fluid, engine exhaust, and other organic compounds, as well as carbon monoxide. These may be ingested while on the ground through the bleed air system. The ingestion of hydrocarbons can be very unpleasant to passengers and crew.  
           [0007]    It is known within the art to remove hydrocarbons through catalyst compositions. By way of example, U.S. Pat. No. 6,203,771 discloses a catalyst and a method for destroying such compounds through oxidation. While the &#39;771 patent represents significant advancements in the art, it would be desirable to provide a system and method that will destroy both ozone and hydrocarbons simultaneously. Also, it would be desirable to provide a system and method that uses the support (washcoat) to destroy ozone, rather than merely providing surface area support for a catalyst.  
           [0008]    As can be seen, there is a need for a combined hydrocarbon/ozone converter for airplane bleed air system that is efficient, effective, may be easily integrated with existing airplane bleed air systems, has low weight and low pressure drop, and reduces impact on existing environmental control systems and the plane&#39;s fuel consumption.  
         SUMMARY OF THE INVENTION  
         [0009]    The present invention provides a method and system that simultaneously destroys ozone and hydrocarbons within an airplane bleed air system. Because the system described herein combines both the objectives of destroying ozone and hydrocarbons within a single system, it is efficient, effective, reduces a plane&#39;s fuel consumption because it has lower weight than two systems, reduces impact on existing environmental control systems because it has lower pressure drop than two systems, and may be easily integrated with existing airplane bleed air systems.  
           [0010]    According to one embodiment, an ozone and hydrocarbon destroying system for an environmental control system of an aircraft is disclosed. This catalytic converter may comprise a core, an active metal oxide washcoat applied to the core for destroying ozone, and an active metal impregnated in the washcoat layer for destroying hydrocarbons.  
           [0011]    According to yet another aspect of the present invention, an ozone and hydrocarbon destroying system for an environmental control system of an aircraft comprises a metal core, a surface layer formed from a portion of the core by mechanical, chemical, electrochemical, or thermal means, an active metal oxide washcoat for destroying ozone and containing manganese oxide or cobalt oxide applied to the surface layer, and an active metal, being platinum, impregnated in the active metal oxide washcoat for destroying hydrocarbons.  
           [0012]    According to a still further aspect of the present invention, an ozone and hydrocarbon destroying system for an environmental control system of an aircraft comprises an aluminum core with a plurality of fins; an aluminum oxide anodized surface layer formed from a portion of the core; an active metal oxide washcoat containing manganese oxide or cobalt oxide that destroys ozone applied to the anodized surface layer; and an active metal impregnated in the active metal oxide washcoat that destroys hydrocarbons, wherein the active metal is platinum, and is loaded at 0.5-15% by weight of the manganese or cobalt oxide.  
           [0013]    According to another aspect of the present invention, an ozone and hydrocarbon destroying system for an environmental control system of an aircraft comprises a core, a high surface area refractory metal oxide washcoat applied to the core, a first active metal impregnated into said washcoat for destroying ozone, and a second active metal, also impregnated in the washcoat for destroying hydrocarbons.  
           [0014]    According to yet another aspect of the present invention, an ozone and hydrocarbon destroying system for an environmental control system of an aircraft comprises a core, a surface layer formed from a portion of the core by mechanical, chemical, electrochemical, or thermal means, a high surface area refractory metal oxide washcoat applied to the surface layer, a first active metal impregnated into said washcoat that destroys ozone, wherein said first active metal is manganese oxide or cobalt oxide and a second active metal impregnated into said washcoat that destroys hydrocarbons, wherein said second active metal is platinum  
           [0015]    According to a still further aspect of the present invention, an ozone and hydrocarbon destroying system for an environmental control system of an aircraft comprises an aluminum core with a plurality of fins; an aluminum oxide anodized surface layer formed from a portion of the core; a high surface area refractory metal oxide washcoat applied to the anodized surface layer, a first active metal impregnated in said washcoat that destroys ozone , wherein said first active metal is manganese or cobalt; and a second active metal impregnated in the washcoat that destroys hydrocarbons, wherein the second active metal is platinum and is loaded at 0.5-15% by weight of the washcoat.  
           [0016]    In a further aspect of the present invention, a method of preparing a core, so as to provide a combined hydrocarbon-destroying and ozone-destroying converter for an airplane bleed system is disclosed comprising: treating the converter core with an active metal oxide washcoat that has a high efficiency for the removal of ozone; and impregnating the washcoat with an active metal, wherein the active metal has a high efficiency for the conversion of hydrocarbons to carbon dioxide and water.  
           [0017]    In still another aspect of the present invention, a method of treating a catalytic converter core, so as to provide a combined hydrocarbon-destroying and ozone-destroying converter for an airplane bleed system is disclosed comprising: coating the converter core with a washcoat, wherein the washcoat contains a high-surface area refractory metal oxide; drying and calcining said washcoated core; impregnating the washcoat with a salt of a first active metal and a salt of a second active metal; and drying and calcining the impregnated and washcoated core.  
           [0018]    In yet another aspect of the present invention, a method of destroying ozone and hydrocarbons in airplane bleed air is disclosed comprising: passing ozone and hydrocarbon containing air through a catalytic converter, wherein the catalytic converter contains a core selected from the group consisting of a ceramic monolith, a metal monolith composed of straight channels, a metal monolith composed of a plurality of fins enclosed by a shell, or layers of fins stacked in an alternating manner to form a heat exchanger; a washcoat on said core that contains a first active metal that has a high efficiency for the removal of ozone, and that contains a second active metal that has a high efficiency for the conversion of hydrocarbons to carbon dioxide and water.  
           [0019]    These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description and claims. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]    [0020]FIG. 1A depicts a schematic aircraft environmental control system according to the present invention;  
         [0021]    [0021]FIG. 2 depicts a cross sectional cutaway view of a portion of a catalytic converter according to the present invention;  
         [0022]    [0022]FIG. 3 is a perspective view illustrating a portion of a plate-fin element having a succession of offset fin rows according to the present invention;  
         [0023]    [0023]FIG. 4 depicts a flowchart of a method of preparing a catalytic converter according to the present invention;  
         [0024]    [0024]FIG. 5 depicts a flowchart of a method of preparing a catalytic converter; and  
         [0025]    [0025]FIG. 6 depicts a method of destroying ozone and hydrocarbons in airplane bleed air 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0026]    The following detailed description is of the best currently contemplated modes of carrying out the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims.  
         [0027]    The present invention is particularly useful within an aircraft environmental control system (“ECS”). However, the present invention is not intended to be so limited. Previously, in an ECS, ozone could be destroyed using one method or system, and hydrocarbons destroyed according to another method or system. As such this was inefficient and costly, requiring two separate systems and methods for their use. The present invention provides a method and system that simultaneously destroys hydrocarbons and ozone.  
         [0028]    In FIG. 1, an ECS  10  may receive compressed air  11  such as bleed air  61  from a compressor section of the aircraft&#39;s main engine  42 , or bleed air  51  from an auxiliary power unit (APU)  44 . A valve  40  selects whether the compressed air  11  is supplied by the main engine  42  or the APU  44 . Typically, during ground operations APU bleed air  51  is selected. During flight, main engine bleed  61  is selected. Alternatively, air  11  may be supplied by a dedicated air compressor both in flight and on ground.  
         [0029]    The bleed air may be at a flow between 1 and 250 lbs air flow/min. The ECS  10  may include a catalytic converter  18 , which may be located in the belly of the aircraft, between the source of the compressed air  11  and the air conditioning system (“ACS”)  14 The catalytic converter  18  may be mounted inside a shell  20  through which the compressed air  11  flows. The compressed air  11  passes through the catalytic converter  18 , which may simultaneously destroy both ozone and hydrocarbons in the compressed air. Filtered air  17  exits the converter  18  and may pass through at least one air-to-air heat exchanger  12  before entering the ACS  14 . The ACS  14  may include an air cycle machine and a water extractor for cooling the compressed air  17  to a desired temperature and reducing moisture to a desired level. The ECS  10  may supply cooled, conditioned air  15  to a cabin  16  or other compartment of the aircraft.  
         [0030]    A pre-cooler  13  may be located upstream from the catalytic converter  18 , in-between the main engine  42  and valve  40 . The pre-cooler  13  lowers the temperature of the compressed air from the main engine  42  prior to ozone destruction and conversion of hydrocarbons. The washcoat and catalyst may optionally be applied to the pre-cooler  13  for the simultaneous destruction of hydrocarbons and ozone. In this case, a separate core is not needed. Anodization may or may not be employed depending upon the material of construction of the precooler.  
         [0031]    [0031]FIG. 2 illustrates a cross-section of a surface of a portion of the catalytic converter  18 . The catalytic converter  18  may include a core  22 , which in the preferred embodiment consists of an aluminum substrate, an anodized surface layer  24  formed from a portion of the core, a washcoat layer  26  with a first active metal  28  impregnated in the washcoat layer  26 , and a second active metal  25  impregnated in the washcoat layer  26  containing the first active metal  28 . The core  22  described throughout may be a heat exchanger.  
         [0032]    The anodized core  24  provides a support for washcoat layer  26 . The anodized surface layer  24  may have a thickness between about 2.0 to 10.0 microns, for example. The anodized surface layer  24  may be dense at the interface with the core  22 . It may also have a rough surface at the interface with the washcoat layer  26 .  
         [0033]    The first active metal and second active metal may be impregnated both in the washcoat layer  26  and the anodized surface layer  24 . Concentration of both the first active metal  28  and the second active metal  25  in the washcoat layer  26  may be higher than the concentration in the anodized surface layer  24 . The washcoat layer  26  is a refractory metal oxide such as alumina, silica, titania, zirconia, or combinations thereof. The first active metal  28  may be selected from the group consisting of manganese, palladium, copper, silver, iron, cobalt and nickel or any combination thereof. According to a preferred embodiment, the first active metal is either cobalt or manganese, and may be present at weights less than or equal to the washcoat weight. The second active metal  25  may be selected from the group consisting of platinum, gold, iridium, rhodium, manganese, copper, iron, nickel or any combination thereof. According to a preferred embodiment, the second active metal may be platinum and may be loaded at 0.5-15% by weight of the washcoat. The first active metal  28  and second active metal  25  will act as catalysts to simultaneously destroy ozone and hydrocarbons, respectively.  
         [0034]    When a stream of compressed air  11  containing ozone and hydrocarbons is directed across the catalytic converter  18 , the ozone containing compressed air  11  interacts with the first active metal  28  within the washcoat layer  26  to decompose a majority of the ozone through the reaction  20   3 → 30   2 .  
         [0035]    The compressed air  11  may contain hydrocarbons. The hydrocarbons can interact with the second active metal  25  to decompose the hydrocarbons into carbon dioxide and water. This results in a filtered air stream  17  flowing past the converter  18  to the ACS  12 .  
         [0036]    The anodized surface layer  24  may be formed through electro-chemical transformation of the surface of the core  22 . Anodizing is an electrolytic oxidation process, which has been used to provide a surface coating on aluminum for protection or decoration of the aluminum or to create a porous layer, which can be used as a catalyst support. The process generally involves establishing an electrolytic cell with the aluminum structure as the anode. Passing an electric current through the aluminum oxidizes the surface to an adherent aluminum oxide. Because the anodized surface layer  24  is an integral part of the core  22 , the anodized surface layer  24  significantly improves the binding strength between the core  22  and the washcoat layer  26 .  
         [0037]    The binding strength may be further enhanced through chemical cross-linking between the metal oxide of the anodized surface and a resin (e.g., an organosiloxane resin) during washcoat formation. Therefore, the washcoat layer  26  has a strong adhesion to the anodized surface layer  24  and may be semi-flexible in the event the core  22  deforms. As a result, the anodized surface layer  24  lessens the likelihood that the washcoat layer  26  will flake off when the catalytic converter  18  is subjected to high temperatures, large temperature swings, and strong vibrations during normal flight conditions.  
         [0038]    The washcoat layer  26  according to another embodiment of the present invention may contain oxides of the said first active metal  28  such as cobalt or manganese, palladium, nickel, iron, copper or silver, so that the washcoat  26  itself may destroy ozone contained within a compressed air stream. For example, the washcoat may be manganese or cobalt oxide instead of a refractory metal oxide. The active metal oxide washcoat is impregnated with the aforementioned second active metal or combination of metals as described supra. When an active metal oxide washcoat is used, it may be desirable to provide further adhesion though the application of an underlayer  27  prior to the washcoat. The underlayer  27  may be between the anodized surface layer  24  and the washcoat layer  26 .  
         [0039]    The core  22  may also be made of titanium, stainless steel, inconel, nickel alloy, cordierite, silicon nitride, alpha aluminum oxide, or other ceramic composite materials. If the core  22  is formed of metal (other than aluminum), treatment of the surface by thermal, chemical, or mechanical means may be used to increase the adhesion of the washcoat. For example, a thin oxide layer may be formed on the surface of the core  22  by heating in air prior to application of the washcoat  26 . Or, the surface may be etched by strong base or acid. Alternatively, the surface may be mechanically roughened.  
         [0040]    It is also well known that many core geometries may be utilized to support catalyst compositions thereon. The core may be a straight-channel ceramic monolith, or straight-channel metal monolith, or may be a metal core  22  composed of a plurality of fins  31 , as shown in FIG. 3.  
         [0041]    A monolith is a substrate body having a plurality of fine, parallel gas flow channels extending through the body. Such substrates may be extruded from ceramic-like compositions such as cordierite or other similar highly refractory materials. A disadvantage of using a straight-channel monolith as a catalyst core is the mass transfer limitation that occurs throughout most of the channel length. Near the channel entrance, the flow is turbulent, providing for better gas-solid interaction, and higher conversion efficiencies. Beyond the entrance section of the channel, the flow quickly becomes laminar, and the gas-solid interaction is not as efficient. It is known in the art to use segmented monoliths in order to improve the monolith mass transfer characteristics.  
         [0042]    Monoliths may also be machined out of metal. Metal substrates are conventionally made by spiral-winding a corrugated metal strip into a coil with the corrugations running parallel to the longitudinal axis of the coil to provide a plurality of fine, parallel gas flow passages extending through the metal substrate. The cross-section of the passages may be triangular, circular, square, rectangular, etc. The coil is stabilized to prevent “telescoping” of the spiral-wound metal strips by the utilization of pins or other mechanical fasteners driven through the coil or by brazing or spot or resistance welding the wound metal strip layers to each other. Such brazing or welding may take place either at one or both end faces, throughout the body, or at selected portions of the body, as is well known in the art. The limitations mentioned above for straight-channel ceramic monoliths apply also to metal monoliths with straight channels.  
         [0043]    An alternative to a straight-channel monolith is a metal core  22  composed of a plurality of fins  31 . The fins  31  may be arranged in an axial succession of adjacent rows  30 , with the fins  31  preferably having a corrugated configuration of generally rectangular profile. The fins  31  of each row  30  may be laterally staggered or offset relative to the fins  30  at the adjacent leading and trailing sides. Each fin  31  element may have layers coated on them, as discussed above. This construction provides a large plurality of small tortuous air flow paths  32  extending axially through the converter core  22  to achieve intimate mass transfer between the incoming compressed air  11  stream and the first active material  28  and second active material  25  which act as catalysts. The efficient decomposition of ozone and hydrocarbons in the flow compressed air  11  stream is accomplished with relatively minimal pressure drop across the converter core  22 . Therefore, the construction with a plurality of small air flow paths  32  eliminates the need to create a turbulent flow, as may be desirable with monolithic supports. A core with a plurality of fins will have higher conversion efficiency than a monolith core of the same dimensions. Or, the core with plurality of fins will be smaller than a monolith core for the same conversion efficiency.  
         [0044]    The substrate forms a core  22  that allows the compressed air  11 , which may be bleed air, to flow through and contact the washcoat layer  26  and the active metal or metal oxide  28  and active metal  25  on the substrate which forms the core  22 . The bleed air may have a flow between 1 and 250 lbs air flow/min at a pressure between 10 and 50 psia, and space velocities of 15,000 and 1,000,000 hr-1. According to the preferred embodiment, as depicted in FIG. 1A, the system according to the present invention may be installed after the valve  40  so that both the main engine stream  61  from main engine  42  and auxiliary power unit (APU) air  51  from APU  44  can be cleaned.  
         [0045]    Alternatively, the core  22  may be located somewhere along the airplane&#39;s APU bleed duct and will remove hydrocarbons ingested by the APU  44 , typically when it is operating on the ground. However, it will not treat the main engine bleed stream, so any atmospheric ozone in the bleed will not be converted. Because of this, it is envisioned that the washcoat layer  26 , the active metal oxide  28 , and the active metal  25  may be applied to existing equipment, such as a precooler  13  in order to treat the main engine bleed  61 .  
         [0046]    The present invention also envisions a method of preparing a catalytic converter  18 , so as to provide a combined hydrocarbon-destroying and ozone-destroying catalytic converter  18  for an airplane bleed system as in the present invention. The method is shown in FIG. 4. A core  22  is selected, preferably made of aluminum. A step  50  of anodizing the core  22  may be performed. Alternatively, and especially when the metal is not aluminum, the surface of the core  22  may be treated thermally to create a thin oxide surface layer, chemically with strong base or acid, or mechanically by roughening. The step  52  includes applying a refractory metal oxide washcoat layer  26  to the core  22 . The washcoat layer  26  may be created by forming a slurry of a refractory metal oxide such as alumina and a synthetic liquid resin containing silicones, siloxanes, and organic solvents, applying the slurry to the anodized surface layer portion  24 , blowing excess slurry from the core channels, heating, curing, and calcining to form the washcoat layer  26  on the channel surface.  
         [0047]    The slurry may be applied by dipping the anodized core into the washcoat slurry, which will form the washcoat layer  26 , so that the surfaces of the fine gas flow passages of the core  22  are completely coated by the washcoat slurry. Alternatively, washcoat slurry may be applied by drawing the washcoat slurry through fine gas flow panels in the core  22  by suction. Excess slurry may be blown out of the gas flow channels within the core  22  with compressed air. The step  56  may be drying in air, and then calcining in air at a temperature of about 300° C. to 600° C. for a period of from about one-quarter to two hours, in order to fix the washcoat  26  to the anodized surface layer  24 . The washcoat may be applied by performing these steps once or several times each. The washcoat layer  26  may have a surface area of at least 20 m 2 /g (surface area of washcoat in square meters per weight of washcoat in grams) and preferably greater than 150 m 2 /g.  
         [0048]    Next, a step  58  of impregnating the washcoat layer  26  with a first active metal  28  and a second active metal  25  may be performed. The active metal  28  has a high efficiency for the conversion of ozone to oxygen. The metal  28  may be selected from the group consisting of manganese, cobalt, palladium, copper, silver, iron, nickel or any combinations thereof. The active metal  25  has a high efficiency for the conversion of hydrocarbons to carbon dioxide and water. The metal  25  may be selected from the group consisting of platinum, gold, iridium, rhodium, manganese, copper, iron, nickel or any combination thereof. Alternatively, the step  58  may be accomplished by impregnating the first active metal separately from the second active metal. Whichever way is chosen, step  58  may be performed once or a number of times until the desired loading is achieved. Next, step  60  may comprise drying and calcining the core  22 .  
         [0049]    [0049]FIG. 5 depicts another method of preparing a catalytic converter. A core is coated with an active metal oxide washcoat and impregnated with a catalytic metal in order to provide a combined hydrocarbon-destroying and ozone-destroying converter for an airplane bleed system. In a preferred embodiment, the core is aluminum, and the surface is treated to provide greater adhesion of the washcoat. The method comprises a step  100  anodizing an aluminum core. Next, an optional step  101  is applying an underlayer on top of the anodized surface layer. The underlayer may be a refractory metal oxide such as alumina. The washcoat may be applied to the treated core in step  102  by contacting a portion of the catalytic converter with a slurry of an active metal oxide and a synthetic silicone resin. The active metal oxide is active for the conversion of ozone. According to one embodiment, the slurry may form the washcoat layer  26  and may contain manganese oxide or cobalt oxide so that there is 0.5 to 2.5 g washcoat per cubic inch of core. The washcoat is dried in step  104  and calcined in step  105 . Next, the active metal for hydrocarbon conversion is applied to the converter. This may comprise a step  106  of impregnating the washcoat with the salt of the active metal and a step  107  of drying the impregnated core. The anodized surface layer  24  provides a corrosion barrier that prevents the active metal salt solution from attacking the core  22  causing corrosion. During fabrication of the catalytic converter  18 , the anodized surface layer  24  allows the washcoated core to be fully dipped into a bath containing a solution of the salt of the active metal. Next, a step  108  of calcining to decompose the precursor and produce the active metal may be undertaken. Calcining is well known within the art, and is the process of heating a substance to a high temperature that is below the melting or fusing point, causing loss of moisture, decomposition of the metal salt, and reduction or oxidation. The active metal  25  thus impregnated may have a high efficiency for the conversion of hydrocarbons to carbon dioxide and water and be selected from the group consisting of platinum, gold, iridium, rhodium, manganese, copper, iron, nickel or any combination thereof. In one embodiment, platinum is the preferred metal and may be applied by impregnation with a platinum salt, including platinum nitrate or platinum sulfite acid. The platinum may be present at 0.5-15% by weight of the washcoat.  
         [0050]    According to another embodiment, as shown in FIG. 6, a method of destroying ozone and hydrocarbons in airplane bleed air is disclosed comprising a step  200  of passing ozone and hydrocarbon containing air through a catalytic converter. The converter core may be a ceramic monolith, or be composed of a plurality of fins enclosed by a shell, or layers of fins stacked in an alternating manner to form a heat exchanger. In a preferred embodiment, the core is aluminum and has an anodized surface layer portion. A washcoat may be formed on the anodized surface layer portion by a step  202  of coating the anodized surface layer with a slurry of aluminum oxide and allowing to dry. This may be accomplished according to any known methods including dipping the core, or a portion of the core, into the slurry, and air knifing processes as known within the art. The slurry may also contain a silicone resin. A step  204  of allowing the slurry to dry may be followed. Next, the method comprises a step  206  of curing the core with the dried slurry on it and a step  208  of calcining the cured core. Calcination may be performed between two and ten hours at temperatures about 500 degrees Celsius. The preferred temperature range may be between 200° C. and 600° C. During calcination, the organic material in the washcoat layer  26  is burned off. Also, the chemical bonds cross-linked during the curing stage are transformed into a three-dimensional network of chemical bonds. The metal oxide in the anodized surface layer may be bridged with the metal oxide in the washcoat layer  26  through this network of bonds. After washcoat calcination has been completed, the aluminum oxide may then be impregnated in a step  210  with a cobalt salt or oxide in any amount up to 100% by weight of the aluminum oxide, and a platinum salt in the amount of 0.5-15% by weight of the cobalt oxide, provided that there is 50-400 g Pt/ft 3  of converter present.  
         [0051]    The invention is not limited to the specific embodiments above and envisions a multitude of different methods and systems. By way of example, the washcoat may be disposed on the substrate (or portion of the core), dried, cured, activated, and then impregnated with the active metal or metals. According to another embodiment, the active metal or metals may be combined with the washcoat material prior to disposing on the substrate.  
         [0052]    It should be understood, of course, that the foregoing relates to preferred embodiments of the invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims.