CA2010754C - Catalytic converter/muffler - Google Patents

Abstract

In a catalytic converter for cleaning exhaust gases, comprising a housing having an exhaust gas inlet and an outlet and a sintered, porous catalytic body which is self-sustaining and arranged in said housing, said body comprising a mixture of:
molybdenum, a molybdenum containing compound, or a molybdenum complex in an amount ranging from 1% to 14% by volume; an active compound for affecting absorption of undesired compounds of said exhaust gases selected from the group of clays, charcoal and carbon, and a refractory component.

Description

2(~110754 This invention relates to catalytic converters.

More particularly, this invention relates to such converters which can be utilized in motor vehicles or other like systems, although such convertors may also find application in various other fields.

With reference to motor vehicle catalytic converters, such converters are used to reduce pollution from the combustion products of internal combustion engines utilizing conventional petroleum fuels. The catalytic effect is usually achieved by use of platinum, which initiates various chemical reactions with the chemicals or chemical compounds in the exhaust gas from the engine. Unfortunately, catalysts such as platinum are known to be readily spoiled by "poisoning" of the catalyst - that is, the catalyst becomes inactive due to the deposition of certain contaminants on the catalyst. One such example is lead; if leaded fuel is used in an engine, the lead in the exhaust gases will rapidly destroy the catalytic effect of the platinum, thus rendering the converter useless or of reduced value for its intended purpose.

While there are also other causes of decreased effectiveness or poisoning of the catalyst unit, but in all cases, replacement of the catalytic unit or converter is required in order to maintain its effectiveness, which is an expensive proposition since the units must be discarded and cannot normally be regenerated.

The present invention is concerned with a catalytic converter which is economical to manufacture and is not readily contaminated or poisoned by contAm;nants in a gas stream such as would be encountered in the operation of an internal co-m-~bustion engine, whereby an improved life expectancy of the unit can be achieved.
In accordance with this invention it has been found that the conventional catalytic elements such as platinum, palladium, rhodium and other like precious metals can be el;m;n~ted from the catalytic unit, and that the life of such converters may be extended.
In accordance with one aspect of the present invention, there is provided a catalytic converter for cleaning exhaust gases comprising a housing having an exhaust gas inlet and an outlet and a sintered, porous catalytic body which is self-sust~n;ng and arranged in said housing, said body comprising a mixture of molybdenum, a molybdenum containing compound, or a molybdenum complex in an amount ranging from 1% to 14% by volume, an active compound for effecting absorption of undesired compounds and a substantial amount of at least one refractory component.
In another aspect, the invention provides a method of forming a catalytic converter unit for cleaning exhaust gases comprising forming a slurry containing 1% to 14% by volume of molybdenum or a molybdenum compound or complex, an effective amount of an active compound for effecting absorption of undesired compounds, and a substantial amount of at least one refractory component, forming the slurry into a body member of desired shape and hardening or curing the formed body member to produce a self-sustaining, porous, sintered body member.

2 0 ~ ~ ~ 5 4 The molybdenum constituent used in the present invention may be molybdenum per se, which is normally available as a powder. The so called "pure" molybdenum as currently available commercially actually contains minor impurities, such as silicon, phosphorus, sulfur, carbon and copper. The latter elements are typically present in a "pure" composition in amounts of less than about 10% by weight.
The molybdenum can also be present, in formulating the slurry, as described hereinafter, as a molybdenum compound or complex, and such compounds include, for example, molybdic oxide, ammonium molybdate, or other sesquie compounds of the formula Mo2X3, in which X may be sulfer, oxygen, selenium, tellurium, or the like, such as molybdenumtrioxide, molybdenum dioxide, as well as mixtures of such compounds. Also, compounds of the formula MoX2 can be employed, where X may be represented by the above substituents.
The composition used to form the slurry, and indeed the resulting hardened composition may contain the conventional components usually associated with catalysts used in a catalytic convertor; thus for example there may be included conventional inorganic -and organic fillers such as silica, glass fibers, powdered metals such as cobalt ( which also acts as a sintering catalyst) etc. Likewise, such compositions may also include various refractory components such as ceramics, etc. Since the compositions are normally formulated as a slurry to formulate them into a desired self-sustaining mass which in turn is normally incorporated into a body or housing, the compositions will also include processing additives such as refractory additives if the composition is to be sintered. Thus refractory catalysts may be included such as a magnesium compound eg. magnesium oxide, inorganic clays, etc.

The catalytic composition for the present invention may be in the form of sheets or other geometrical configurations such as blocks or "cakes"
of catalytic material, characterized in that they are in a generally self-sustaining form and preferably in a porous condition. The porous structure for the catalytic compositions is obtained by forming a slurry of a mixture of the various components of the composition, together with the ceramic materials, and thereafter placing the slurry into a mold of any desired shape and size followed by firing of the mixture to harden the same.

In order to form a structure of relatively high porosity, or a "honey-comb" configuration, a gas may be passed through the slurry to form entrapped gas within the slurry. This basically results in the formation of a foam and depending on the desired porosity, the amount of gas (such as air) used to generate a foam mixture can be varied and in addition, bubble sizes may be controlled or varied to provide 20~075~
different porosities.

With the application of heat during firing, the bubble size will generally increase due to heating and coalescence of the bubbles does not generally occur.

Firing temperatures will vary depending on the components involved but typically for ceramic base compositions will vary between 1900F to 2500F.
After firing, the mixture is then permitted to dry which forms the open pore or porous structure of the catalytic composition.

The compositions of the present invention include a ceramic base and as such, conventional ceramic materials may be used for this purpose. It will be understood that various types of materials are employed in the formulation of ceramic bases and as such, the ceramics known in the art may be employed to formulate the compositions of the present invention.
Cermet compositions may also be employed (cermet compositions being those formed from ceramic compositions by bonding the refractory materials with powdered metal carbides). Both the ceramic and cermet compositions are commercially available, being compacted or sintered for use. Hereinafter, all compositions are by volume.

In the compositions of the present invention, optional additives include osmium, tungsten.... These compounds function as variably as additional reactive agents and strengthining agents, and if included in the compositions, are desirably present in amounts ranging from about 1% to 8% by volume, and preferably about 4% to 7% by volume.

The compositions will also include the necessary 2~ S4 active components for effecting absorption of the converted undesired compounds or components of the exhaust gases and to this end, activated compounds such as various types of clays, charcoal and the like may be employed. Various additives useful in the formation of ceramic based compositions can be included such as zircon which may be included in amounts ranging from about 6% to about 8%. Zircon, or a zirconium compound such as zirconium dioxide, may be used to reduce the coefficient of expansion or decrease the volume of the slurry, as well as increasing the dielectric characteristics. As is known, zirconium has high resistance to corrosion and thus forms a desirable additive in the compositions.
The above and other conventional components of the compositions of the present invention may be present in varying amounts as will be understood by those skilled in the art.In the case of the molybdenum or molybdenum containing compound, the amount of the active ingredient will vary considerably but it has been found that suitable amounts vary between about 1%
to about 14%, based on the volume of the total composition when used as a slurry in forming the product of this invention, and more preferably between about 8% to about 11%. When calculated on the basis of a sintered product, the amount of the molybdenum will also be present, whether as a compound or a complex, from about 1% to about 14%, and preferably from about 7% to about 11%, of the hardened composition..

The final form of the composition can vary considerably; to this end the compositions of this invention will generally be in the form of a self-sustaining mass which is of a porous nature.Typically, the porosity of the products is such that the mass will have a density of from about 26 to about 2~t~07~

35, and more preferably from about 26 to about 30. It will be understood that compositions may also be formed into thin sheet-like structures where the exhaust gasses may pass over the surfaces of such structures to be treated, depending on the type of application contemplated.

The catalytic compositions of the present invention are characterized by having a porous structure, as well as being dimensionally stable and by the various components of the composition being homogeneously distributed throughout the mixture.

In accordance with an optional feature of the present invention, the catalytic converters can include means for introducing a reactive fluid, such as a reactive gas, into the converter. By way of example, when the converter comprises a housing including the catalytic composition contained therein, the housing may include an inlet connected to a source of fluid, such as a source of pressurized gas, which may be used to aid in the reaction of the various components of the gases being treated which is catalyized by the catalytic compositions of the present invention. One typical example involves the introduction of e.g., hydrogen, into the chamber containing the catalytic composition; to this end, the housing may include an air tight fluid connection to a source of hydrogen, which may be metered by suitable valve means. Another gas which can be introduced is oxygen. Thus, the invention may include, in this embodiment, suitable controllable valve means or metering means such as a metering pump to dispense desired quantities of one or more reactive gases into the catalytic device.

Having thus generally described the present - 8 ~ 20 1 0754 invention, reference will now be made to the accompanying drawings illustrating preferred embodiments and in which:
Figure 1 is a diagrammatic cross-section through a converter unit, which also illustrates the conversion process;
Figure 2 is a plan view of one embodiment of the converter unit of the present invention;
Figure 3 is an end view of the converter unit of Figure 2;
Figure 4 is an end view of an alternate catalytic converter of the present invention;
Figure 5 is a horizontal section taken through the converter of Figure 4;
Figure 6, which appears on the same sheet as Figure 4, is an end elevation view of the baffle used in the converter of Figures 4 and 5;
Figure 7 is a horizontal sectional view taken through a two stage catalytic converter of the present invention;
Figure 8 is a vertical cross-section through a two stage combined catalytic converter according to the present invention;
Figure 9a is a horizontal sectional view taken through a modified catalytic converter of the present invention;
Figure 9b is an end view of the catalytic converter of Figure 9a;
Figure lOa is a horizontal sectional view taken through another modified catalytic converter of the present invention;
Figure lOb is an end view of the catalytic converter of Figure lOa;

- 8a Figure 11 is a horizontal sectional view taken through a further two stage catalytic converter of the present invention;
Figure 12 is a horizontal sectional view taken through another two stage catalytic converter of the present invention; and Figure 13 is a horizontal sectional view taken through a combined exhaust pipe, catalytic converter and muffler according to the present invention.
Referring now to Figure 1, there is illustrated a diagrammatic representation of a catalytic converter for an internal combustion engine which generates exhaust gases. The converter includes an inlet 10 and an outlet 12 as well as a main body 11. Typically, exhaust gases entering the converter unit from an internal combustion engine include gases such as NOx, CO and hydrocarbon gases (that is oxides of nitrogen, carbon monoxide, and other spent and non-combusted hydrocarbon gases). The gases flow, by pressure of the exhaust system, into the main body 11 of the converter where there is the catalytic conversion, which under conventional techniques is based on platinum. At this point, various reactions take place, where the contaminants are at least partially converted into H20, C02, N2 and 0. The gases thus exhausting from the converter at outlet 12 are a mixture of the converted gases and the non-converted contaminants, e.g. carbon monoxide, carbon dioxide, hydrocarbon gases in general, water, etc.
Two opposing chemical processes - reduction and oxidation - are needed to eliminate the three main automotive pollutants, oxides of nitrogen, carbon monoxide and hydrocarbons. Reduction strips oxygen atoms from oxides of nitrogen, compounds that contribute to smog, leaving elemental nitrogen and oxygen. Oxidation adds oxygen atoms both to carbon monoxide and to unburned hydrocarbons. As the exhaust passes over the catalyst, a molecule of poisonous carbon monoxide receives an additional oxygen atom and becomes essentially harmless carbon dioxide. At the same time, the hydrocarbons, whlch are the main ingredients of smog, combine with oxygen to become carbon dioxide and water vapour. Catalysts, however, :' ~

-- lO 20 1 0754 are sensitive to extreme temperature variations and can be ruined by a misfiring engine. Catalysts are also vulnerable to lead and other contaminants in gasoline. Figure 1 shows an idealized converter combining both oxidation and reduction reactions in a single canister. Oxides of nitrogen (NOX), carbon monoxide (CO) and hydrocarbons (HC) pass through the catalysts and emerge as water vapour (H2O), carbon dioxide (CO2), nitrogen (N2) and oxygen (2). In actual practice, reduction occurs first, then air is injected into the exhaust stream, providing oxygen for oxidation.

Referring now to Figures 2 and 3, there is illustrated one particular form of a catalytic converter of the present invention which is suitable for use in an exhaust system of a motor vehicle utilizing an internal combustion engine. The converter includes a body having a hollow housing 20 I formed from two halves 21 and 22 having peripheral flanges 23. The flanges 23 are joined together by suitable means, such as welding, after a body of porous catalytic material 24 has been mounted within the body halves 21 and 22. An entry port or inlet 25 is provided at one end of the body and an exhaust or outlet port 26 at the other end of the body; these inlet and outlet ports 25 and 26 may be suitably connected to an exhaust conduit of a vehicle at an appropriate point.
The catalyst, in the form of a porous sinteredbody 24, has a similar transverse cross-section as that of the main part 27 of the housing 20, and is shown in dotted lines in Figure 2. The length of the catalyst is indicated by the dotted lines 28 and normally, the catalyst 24 will be in a relatively tight fit within the housing 20, being clamped in a position within the 11 20 ~ 07S~ `
two halves 21 and 22.

Referring now to Figures 4 through 6, a catalytic converter similar to Figures 2 and 3 is illustrated but in this embodiment, the converter is modified so as to include front and rear baffles 30 and 32, and as will be noted, the porous catalytic material 24 is substantially the size of the chamber defined by the upper and lower body halves 21 and 22.
The baffle structure shown in Figure 5 comprises a monolithic porous sheet of similar catalytic material to material 24, with the baffle sheet being sized and dimensioned to fit at the inlet and outlet portions of the converter (Figure 5).

As will be seen from Figure 6, the baffle 32 is mounted to a supporting plate 33 which in turn, is secured to the lower body portion 22. A similar t structural arrangement may be employed for baffle plate 30.

If desired, the baffle plates 30, 32 may be provided with a different catalytic composition compared to the catalytic material 24.

In the embodiment illustrated, the catalytic material 24 can be formulated from a slurry consisting of the following components in the following amounts by volume.

SLURRY FORMULATION PERCENTAGE
Powders:
Activated Carbon 16 Boron 6 Nickel and Compounds . 8 Molybdenum 7 Ceramics and Compounds 47 Fibers 6 Copper 5 : Stainless Steel 5 ' 12 ~01 ~75~

An alternate arrangement is illustrated in Figure 7, in which a two stage catalytic converter is illustrated. Similar reference numerals describing similar components are used in Figure 7 as well as in subsequent Figures.

Referring to Figure 7, the inlet 25 of an exhaust system leads to a first stage catalytic reaction zone indicated generally by reference numeral 40, which in turn, leads to a second stage catalytic reaction zone indicated generally by reference numeral 42. Each of the reaction stages are connected by an intermediate zone 44; the second stage leads to an exhaust outlet 26.

The first stage catalytic zone comprises an enlarged area of the converter relative to the inlet where exhaust gases are thus reduced in pressure.
This enlarged area, indicated generally by reference numeral 46, contains a first stage catalyst whose function is to catalyse gases. The first stage housing includes a continuous outer shell 48 from the inlet 25 through to the outlet 26; this housing may be formed of suitable material as otherwise described herein.

The housing 48 at the second stage, comprises an elongated chamber 50 containing a second stage catalyst 52 according to this invention.

The housing 48 at the second stage, comprises an elongated chamber 50 containing a second stage catalyst 52 according to this invention. This catalyst can be formed from a slurry comprised of the catalytic composition of the present invention.

As will be seen from Figure 7, the catalytic composition is preformed to a generally elongated structure with a space or gap between the housing wall 48 and the catalytic composition 52 with an impervious front surface 53. Exhaust gases flow from the first stage into the space 50. Space 50 acts as an anti-resonator and is blocked at the end remote from the inlet by a diaphragm 5. The gases will flow into and through the porous composition 52 from the space 50 as indicated by arrow 56.

The first stage catalytic composition was formed from a slurry made up of SLURRY COMPONENTS PERCENTAGE
Powders:
Activated Carbon 24 Ceramics 56 Cobalt 10 Nickel 10 t The second stage catalytic composition was formed from a slurry made up of SLURRY COMPONENTS PERCENTAGE
Powders:
Boron and Compounds 6 Activated Charcoal 16 Stainless Steel 8 Copper 7 Silica Alumina 13 Molybdenum and Compounds 8 Ceramics 42 With reference to Figure 8, there is illustrated a two stage reactor with one stage surrounding the other, used as a catalytic converter. In this embodiment, the converter includes an outer housing 57 made up of upper and lower halves 57a and 57b joined together about their periphery. In the converter, a hollow central core or passage 59 is provided, defined by a passage through a second stage catalytic composition 61, as described hereinafter, and which in turn, is surrounded by a first stage catalytic composition 63, also defined hereinafter.

In use, gases from an exhaust system permeate through the first stage catalytic composition into and through the second stage catalytic composition, and finally exhaust from the catalytic unit through an outlet port (not shown).
The above type of converter is used for treating exhaust gases from an internal combustion engine up to e.g. 19,000 c.c.

The first stage catalytic composition was formed using a slurry, as follows SLURRY COMPONENTS PERCENT
Powders:
Ceramics and Compounds 53 Vanadium and Compounds 6 Nickel and Compounds 9 Activated Carbon 16 Silica-Alumina 9 Shredded Fibreglass 2 Copper 5 The second stage catalytic composition was formed from a slurry made up of SLURRY COMPONENTS PERCENT
Powders:
Ceramics 27 Stainless Steel 8 Molybdenum and Compounds 6 Cobalt and Compounds 7 Activated Charcoal 14 Talc 11 Zirconium 5 Nickel 4 Alumina Silica 5 Activated Carbon 9 Osmium 2 Thorium 2 Also, as shown in Figure 8, there is provided an inlet 58 capsule which creates an immediate reduction in the emissions, and produces hydrogen which flows within the catalyst.

Another variation of the present invention is illustrated in Figure 9, in which an inlet 25 receives a flow of exhaust gases to be treated. In this case, the catalytic converter includes a continuous housing 60 with a first enlarged chamber 62, a subsequent reduced area 64 and a further enlarged area 66 of a greater dimension than area 62. A further chamber 68 dimensioned similar to chamber 62 follows chamber 66 and finally, a second enlarged chamber 70 follows chamber 68. Areas of reduced cross section or diameter 72, 74 are between chambers 66 and 68 and chambers 68~
and 70 respectively. Chamber 70 reduces in size to an outlet 26.
Chambers 62 and 68 are empty and serve as anti-resonant chambers, while within each of the other chambers a core of material forming the catalytic composition of the present invention is located. This core of material substantially fills each chamber and in each case, the composition comprises:

SLURRY COMPONENTS PERCENT
Powders:
Activated Charcoal 11 Thorium and Compounds 6 Zinc and Compounds 5 Molybdenum and Compounds 7 Osmium and Compounds 4 Ceramics and Compounds 44 Stainless Steel 8 Copper 15 The catalytic converter shown in Figure 9 may be used for exhaust systems connected to internal combustion engines of e.g. up to 4,000 c.c., and has been found to be highly significant at reducing toxic emissions from said engines.

An alternative arrangement is illustrated in Figure 10, again showing a multistage catalytic converter. In this case, the converter is connected to an inlet 25 and an outlet 26 and the converter includes a body or housing 80 of a sinusoidal configuration in cross section. In effect, enlarged chambers indicated generally by reference numerals 82, 84, 86, 88 and 90 are formed. All chambers can be filled with the material detailed below but in an alternative arrangement one or more of the chambers can act as anti-resonant chambers.
The following slurry composition was formulated and the resulting porous material utilized to fill the catalytic converter.
SLURRY COMPONENTS PERCENT
Powders:
Ceramic Base 56 Boron 5 Osmium 6 Silica Gel 4 Nickel 8 Activated Carbon 8 Vanadium 5 Stainless Steel 4 Copper 4 The catalytic converter of Figure 10 may be used for treating exhaust gases from internal combustion engines of up to e.g. 13,000 to 14,000 c.c.
Referring now to Figure 11, a converter similar to that shown in Figure 9 is illustrated but in this case, a "dual" converter is shown. Dual inlet ports 25 and 25' are shown, each leading to separate primary treatment chambers 100 and 100'. Treatment chambers 100 and 100' are contained within a single housing 102, divided by a gas impermeable partition 104 of suitable material. Exhaust gases flow from treatment chambers 100 and 100' to separate outlets 106 and 106' into conduits 108 and 108' whose length may vary depending on its application.

A secondary treatment chamber, containing a catalytic composition of the present invention, is formed of two chambers 110 and 110' within a single housing 112, which housing is partitioned by use of a divider 114 similar to that described for the primary treatment zone.

Each of chambers 100 and 100' and 110 and 110' is 15 provided with a porous catalytic material formed from a slurry comprising - SLURRY COMPONENTS PERCENTAGE
Powders:
Activated Carbon 18 Clays 25 Boron 11 Lithium 3 Molybdenum 7 Copper 6 Stainless Steel 6 Cobalt 8 Colloids g Niobium Osmium 2 Shape Selection 4 A particular aspect of the present invention, of the device illustrated in Figure 11, is the provision of a hollow housing 112 containing a two semi-cylindrical passageway 116, 116' and communicating with a respective inlet portion connected to a respective conduit 108 and 108'. Hollow passageways 116, 116' are formed by an interior wall 118, which is of a permeable or porous nature but is sufficient to retain a material 120. Gas flows from inlets 108 and 108' along the passageway 116 and 116', passing through the wall 118 into the chamber 110, 110'.
Spaced perforated baffles are positioned along the passageway 116, 116', to induce the gasses to flow into the chambers 110, 110'. The ends of the passageways 116, 116' are closed by impervious diaphragms 119, 119'.

The above catalytic converter is useful for treating exhaust gases of internal combustion engines of up to 16,000 c.c.

Referring now to Figure 12, a two stage catalytic converter similar to that of Figure 7 is shown. In this case, first stage catalytic conversion takes place in the chamber 120, and a second stage in chamber 122, both stages being contained within a single housing defined by a continuous wall structure~
124 and with an intermediate space or chamber 126 separating the primary and secondary chambers 120 and 122.

In this embodiment, typically the first stage comprises a chamber of approximately 8 inches in depth and 3 to 6 inches in length, with the overall housing being of a generally circular configuration extending from the inlet 25 to the outlet 26. A monolithic catalytic composition is included within the chamber 120, indicated by reference numeral 128 and likewise, a further monolithic porous catalytic second stage composition in the form of a "cake" is also included within the chamber 122 as indicated by reference numeral 130.

Chamber 122 can vary between 8 and 12 inches in diameter and may have a length from 8 to 16 inches or more.

~' 2~)~G75 ~

The following slurry formulations were made for the first and second stage catalytic material FIRST STAGE SLURRY COMPONENTS PERCENTAGE
Powders:
Ceramics and Compounds 68 Activated Carbon 17 Molybdenum 6 Stainless Steel g SECOND STAGE SLURRY COMPONENTS PERCENTAGE
Powders:
Activated Charcoal 18 Vanadium 13 Copper and Compounds g Nickel & Cobalt 11 Ceramics 49 The above type of catalytic converter has been found to be useful for treating exhaust gases from internal combustion engines of up to 16,000 to 18,000 c . c .

Figure 13, illustrates a combination exhaust pipe, catalytic converter and muffler as a single unit.

The unit comprises an elongated length of conduit 140 having an inlet 142 adapted to receive exhaust gases from an internal combustion engine, and an outlet 144 to dispense treated exhaust gases.

Conduit 140 includes a plurality of discs 146 of a catalytic composition (described hereinafter) which are mounted in close relationship to each other. The individual discs or blocks 146 of catalytic material may be of various sizes and dimensions but typically they range in width of about 1/4 to 2 inches or more.
Preferably, they are "packed" or loaded into a preformed conduit 140 and will otherwise fit into the conduit 140 according to the contours thereof.

_ 20 2010754 The following slurry formulation was used in formulating the catalytic composition:
SLURRY COMPONENTS PERCENTAGE
Powders:
Ceramics 36 Nickel 14 Molybdenum 4 Activated Carbon 18 Synth. Fused Silica 9 Fireclay 16 Tungsten 3 The housing 20 can be made of any suitable material for this purpose; typically, they may be formed of various types of sheet metal when used as automobile catalytic converters, such metals being e.g. stainless steel, aluminum, carbon steel and other materials. Alternately, they may be non-metallic such as porcelain or the like. The thickness of the material forming the housing can vary, depending upon the size and capacity required for the sintered member and also the various dimensions of the housing will vary depending on the particular use and the amount of sintered material which must be accommodated.

The catalyst is preferably in the form of a sintered porous body or honeycomb structure. The catalyst may be readily produced by forming a slurry of the components, molding the slurry and hardening the slurry as by e.g. firing the mold containing the slurry.

A particularly preferred formulation of a composition for forming a catalyst is as follows WeightPercentage Shredded fibreglass l lb. 40 Nickel powder 25 grams 0.3 Ceramics 318 grams 18 Cobalt powder 25 grams 0.3 Molybdenum 185 grams 8.7 Zircon -56 grams 7.6 High alumina 32 grams 4.3 Activated carbon 38 grams 5.1 Stainless steel powder 28 grams 3.8 Silicon carbide 36 grams 4.9 Refractories 36 grams 4.9 Chromium (refractories) 15 grams 2.1 1249.5 grams 100 A liquid is desirable to form a slurry for manufacturing purposes, and any suitable liquid of a non-reactive nature can be employed for this purpose.
For example, liquids functioning as carriers for molding purposes can be a conventional colloid binder.
The above composition, in the form of a slurry, can thus be formulated into a desired shape by placing the slurry into a suitable mould, firing the same in a furnace and the enclosing the resulting hardened product in a catalytic convertor housing as shown in the drawings referred to above. This formulation is particularly suited to catalytic converters at more than 20,000 cc's, and of two stages.

The following examples illustrate further various catalytic compositions which may be used in carrying out the invention.

The following components were used to formulate a catalyst composition, which can be formulated in the manner described in Example one into a sintered porous catalytic convertor.

2~
~ 22 Palladous Oxide (PdO) - 4%
Powder Metals - Cobalt - 18%
Inorganic Clay - 23%
Activated Charcoal - 11%
Magnesium Oxide - 7%
Molybdenum - 14%
Talc/Fibreglass - 23%
All of the above percentages are by volume.
The PdO compound is employed in this formulation as a catalyst; the powdered metals were utilized as a filler-catalyst sintering agent while the inorganic clay component functioned as a refractory-catalyst agent. The activated charcoal was included in the composition as an emissions absorbent while the magnesium oxide compound was utilized as a refractory catalyst. The talc and fibreglass were present as inorganic fillers.

The molybdenum incorporated into the catalytic composition of the present invention has been found to provide the necessary properties to prevent poisoning of the catalytic system in catalytic converters such as are used for automobiles.

The following components were used to formulate a catalyst in the manner described in Example one:
Inorganic Clay/Fibreglass - 19%
Powdered Metals/Cobalt - 29%
Molybdenum - 14%
Silica-Alumina Catalyst - 12%
FireClay (Activated Carbon) - 24%
Palladous Oxide (PdO) - 2~
All of the above percentages are by volume.
The PdO compound is employed in this formulation as a catalyst; the powdered metals/cobalt were 2~o~s~
_ 23 utilized as a filler-catalyst sintering and non-explosive agent while the inorganic clay/fibreglass components functioned as a refractory-catalyst agent.
The silica-alumina catalyst component was included in the composition as a temperature coefficient agent while the fireclay compound was utilized as a monolithic refractory agent.

The molybdenum incorporated into the catalytic composition of the present invention has been found to provide the necessary properties to prevent poisoning of the catalytic system in catalytic converters such as are used for automobiles.

The following materials were used to formulate a catalyst in a manner similar to that of Example one:
Synthetic Fused Silica (Activated) - 18%
Natural Clay (Activated) - 17%
Stainless Steel Powder/Cobalt - 5%
Refractory (Bonded) Castable - 14%
Fused-Cast-Carbon-Activated Powder - 15 Zircon (Activated Carbon) - 8%
Silicon Carbide/Fibreglass - 5%
Molybdenum - 14~
All of the above percentages are by volume.

The stainless steel powder/cobalt compounds are employed in this formulation as a cermets compounded (catalyst); the refractory bonded castable was utilized as a oxidation resistant (catalyst). The synthetic fused silica catalyst functions as a catalyst support (for resonator); while the natural clay component is used for glassy bond formation. The fused-cast-carbon activated powder functions in the adsorption of gases; while the zircon component functions to reduce the coefficient of expansion. The ~Q~75~

silicon carbide/fibreglass components provide abrasion resistance.

The molybdenum incorporated into the catalytic composition of the present invention has been found to provide the necessary properties to prevent poisoning of the catalytic system in catalytic converters such as are used for automobiles.

Claims (37)

1. A catalytic converter for cleaning exhaust gases comprising a housing having an exhaust gas inlet and an outlet and a sintered, porous catalytic body which is self-sustaining and arranged in said housing, said body comprising a mixture of:
molybdenum, a molybdenum containing compound, or a molybdenum complex in an amount ranging from 1% to 14% by volume, an active compound for affecting absorption of undesired compounds of said exhaust gases selected from the group of clays, charcoal and carbon; and a refractory component.

2. A catalytic converter as claimed 1 wherein said molybdenum or molybdenum containing compound comprises between about 4% and 8% by volume.

3. A catalytic converter as claimed in claim 1 including first and second catalytic stages, said molybdenum containing body being in at least said second stage.

4. A catalytic converter as claimed in claim 3 wherein said molybdenum containing body is in both said stages.

5. A catalytic converter as claimed in claim 1 wherein said catalytic body also includes at least one of boron, nickel, copper, stainless steel, cobalt, vanadium, zirconium, osmium, thorium, zinc, lithium, niobium and tungsten.

6. A catalytic converter as claimed in claim 5 wherein said catalytic body includes between about 4% and 8% boron by volume.

7. A catalytic converter as claimed in claim 5 wherein said catalytic body comprises between 5% and 11% nickel by volume.

8. A catalytic converter as claimed in claim 5 wherein said catalytic body comprises between about 4% and 15% copper by volume.

9. A catalytic converter as claimed in claim 5 wherein said catalytic body comprises between about 4% and 9%
stainless steel by volume.

10. A catalytic converter as claimed in claim 5 wherein said catalytic body comprises between about 7% and 10% cobalt by volume.

11. A catalytic converter as claimed in claim 5 wherein said catalytic body comprises between about 5% and 13%
vanadium by volume.

12. A catalytic converter as claimed in claim 5 wherein said catalytic body comprises between about 6% and 8%
zirconium by volume.

13. A catalytic converter as claimed in claim 5 wherein said catalytic body comprises between 2% and 6% osmium by volume.

14. A catalytic converter as claimed in claim 5 wherein said catalytic body comprises between about 2% and 6% thorium by volume.

15. A catalytic converter as claimed in claim 5 wherein said catalytic body comprises about 5% zinc by volume.

16. A catalytic converter as claimed in claim 5 wherein said catalytic body comprises about 3% lithium by volume.

17. A catalytic converter as claimed in claim 5 wherein said catalytic body comprises about 1% by volume.

18. A catalytic converter as claimed in claim 5 wherein said catalytic body comprises about 3% tungsten by volume.

19. A catalytic converter as claimed in claim 1 wherein said at least one refractory component comprises ceramics between about 27% and 68% by volume.

20. A catalytic converter as claimed in claim comprising at least one stage with said catalytic body in cylindrical form.

21. A catalytic converter as claimed in claim 20 wherein an entry and an exit of said one stage are of reduced area relative to a main body of the stage.

22. A catalytic converter as claimed in claim 20 comprising at least two stages with said catalytic body in each stage, of cylindrical form.

23. A catalytic converter as claimed in claim 22 wherein each stage has an entry and exit of reduced area.

24. A catalytic converter as claimed in claim 22 wherein said two stages are spaced apart.

25. A catalytic converter as claimed in claim 24 including an anti-resonant chamber between said two stages.

26. A catalytic converter as claimed in claim 20 including an anti-resonant chamber before said one stage.

27. A catalytic converter as claimed in claim 20 including an anti-resonant chamber around said one stage.

28. A catalytic converter as claimed in claim 23 including an anti-resonant chamber between said two stages.

29. A catalytic converter as claimed in claim 21 including an anti-resonant chamber before said one stage.

30. A catalytic converter as claimed in claim 5 wherein said catalytic body also includes at least one of shredded fibreglass, talc, silica gel, clays, colloids, synthetic fused silica and fire-clay.

31. A catalytic converter as claimed in claim 1 comprising at least one stage with said catalytic body having an oval cross-section.

32. A catalytic converter as claimed in claim 1 comprising at least two stages with one of said catalytic bodies which have an oval cross-section.

33. A catalytic converter as claimed in claim 22 wherein said at least two stages are arranged in series.

34. A catalytic converter as claimed in claim 22 wherein said at least two stages are arranged in parallel.

35. A method of forming a catalytic converter unit for cleaning exhaust gases comprising:
forming a slurry containing 1% to 14% by volume of molybdenum or a molybdenum compound or complex, an effective amount of an active compound for affecting absorption of undesired compounds of said exhaust gases selected from the group of clays, charcoal and carbon, and a refractory component;

forming the slurry into a body member of desired shape; and hardening or curing the formed body member to produce a self-sustaining, porous, sintered body member.

36. A catalytic converter for cleaning exhaust gases comprising a housing having an exhaust gas inlet and an outlet and a sintered, porous catalytic body which is self-sustaining and arranged in said housing, said body comprising a mixture of:
molybdenum, a molybdenum containing compound, or a molybdenum complex in an amount ranging from 1% to 14% by volume, an active compound for affecting absorption of undesired compounds of said exhaust gases selected from the group of clays, charcoal and carbon; and a refractory component selected from the group of ceramics, cermets and fire-clays.

37. A method of forming a catalytic converter unit for cleaning exhaust gases comprising:
forming a slurry containing 1% to 14% by volume of molybdenum or a molybdenum compound or complex, an effective amount of an active compound for affecting absorption of undesired compounds of said exhaust gases selected from the group of clays, charcoal and carbon, and a refractory component selected from the group of ceramics, cermets and fire-clays;

forming the slurry into a body member of desired shape; and hardening or curing the formed body member to produce a self-sustaining, porous, sintered body member.