DE2339513A1 - CATALYTIC COMPOSITION AND METHOD FOR MANUFACTURING AND USING IT - Google Patents

Description

The invention relates to a catalyst, the one or more Contains metals of the platinum group, and processes for its production and in particular catalytically highly active compositions of matter, that are resistant to high temperatures and at the same time retain good activity over long periods of use. The catalysts according to the invention can be used to accelerate the oxidation of carbonaceous materials, for example of carbon monoxide, hydrocarbons, oxygenated organic compounds and the like, to products with higher oxygen content by weight, such as intermediates an oxidation, carbon dioxide and water, the latter two materials being proportionate harmless materials from the point of view of air pollution

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- are dirt. The new catalysts used to substantially complete oxidation of exhaust gases that are unburned or partially burned carbonaceous Fuel components such as carbon monoxide, hydrocarbons and oxidation intermediates from mainly Contain carbon, hydrogen and oxygen to effect.

The catalysts according to the invention contain a catalytically active calcined mixture of one or more rare earth metals to which one or more metals of the platinum group are added as a component. The calcination erf olgt at temperatures of at least about 750 ⁰ C, preferably about 900 to 1300 ⁰ C, but must not be so high or for such times be maintained may, that the material sinters too strong, so that it no longer sufficient has catalytic activity. The calcined material generally has a surface area of at least about 25, preferably at least about 75 m / g. The surface areas reported are those determined by BET or similar methods. Calcination occurs before the platinum group metal or metals are added to the mixture of rare earth oxides and alumina. The catalysts preferably contain a catalytically relatively inert solid support for the platinum group metal or metals, alumina and rare earth oxide. The catalysts can be prepared in various ways. For example, the mixture of rare earth oxide and aluminum oxide can be calcined and, for example in the form of an aqueous slurry, applied to the inert support, after which the platinum group metal is added and the mixture is then dried. In other methods, the platinum group metal can be added to the calcined mixture of rare earth oxides and alumina and the mixture can then be deposited on the relatively inert support.

It is well known that the combustion of carbonaceous fuels

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materials for energy generation, for example in piston engines or machines with rotating parts and the like., The combustion generally incomplete and often the products of incomplete combustion are vented to the atmosphere. The exhaust gases can include a mixture of contaminants Carbon monoxide, saturated and unsaturated hydrocarbons and oxidized organic compounds such as aldehydes, organic acids and the like. Contain. Air pollution from these and other exhaust gases is particularly high in urban areas, where there is heavy traffic, undesirable. The oxidizable materials released in this way contribute significantly to this Problem of air pollution and the formation of smog and often have a detrimental effect on people, animals and plants exposed to such impurities in excessive concentrations are made.

A means of reducing the oxidizable content of exhaust gases Materials consists in their oxidation by contact with molecular oxygen in the presence of catalysts. the Catalysts are usually placed in the exhaust line leading from the combustion zone and are used for convenience a conversion between the unburned and partially burned fuel components with free oxygen, the either from the operation of the combustion zone with small amounts of fuel or from the outside air or from another Source of oxygen. A disadvantage of most of these catalysts is that their activity is considerably reduced when they are kept at elevated temperatures for a long period of time be used. This is partly due to an unstable structure that sintering at high temperatures takes place, so that the catalyst shrinks and thus the available surface area of the catalyst is reduced. Thermal degradation and loss of strength of the catalyst when used at high temperatures, which occur at Exhaust pipes from combustion engines and turbines over about

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538 or 650 ⁰ C (about 1000 ⁰ P or 1200 ⁰ F) can cause attrition of the catalyst mass, especially when it is used in automobiles where it is subject to considerable vibration. The effect of the catalyst is reduced by the fine particles or other products of structural degradation. In addition, many catalysts can be sufficiently effective in converting carbon monoxide but causing relatively little hydrocarbon conversion. Another problem that must be overcome is that an oxidation catalyst for the treatment of exhaust gases must maintain its effectiveness for a long time, for example for at least 80,000 km (50,000 miles) of driving time of the motor vehicle. If frequent removal and replacement of the catalyst are required to maintain the desired activity, the inconvenience of using and the cost of such a system to reduce air pollution from unburned and partially oxidized components could, and in any event, hinder the introduction of the system entail undesirably high costs.

A relatively large amount of hydrocarbons, carbon monoxide and other partially burned materials get into the initial stages in the commissioning of the machine, if For example, in an internal combustion engine, the combustion zone is cold or at a relatively low temperature, in the exhaust. A good exhaust gas oxidation catalyst therefore works effectively at both such temperatures as well as at the high temperatures at which it is used to further promote oxidation. According to the catalysis factor the invention catalyzes the oxidation of carbonaceous materials at relatively low and at high temperatures, in particular partially burned fuel exhaust gases that contain carbon monoxide, Hydrocarbons and oxidized organic compounds such as aldehydes, organic acids and other intermediate products of combustion, contain, with the formation of carbon dioxide, water or

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other materials that contain on average a larger amount of bound oxygen per molecule. The reaction takes place in the presence of free oxygen to support the oxidation. The new catalyst is heat-resistant, for example up to about 900 ^° C. and above, the heat resistance depending on the carrier used. Such temperatures can occur in the treatment of combustion exhaust gases and exhaust gases from other oxidation systems. Thermal degradation, shrinkage, loss of strength and loss of catalytic activity are minimal with these catalysts. The treatment of exhaust gases with the catalyst according to the invention is effective and frequent regeneration or replacement of the catalyst can be avoided. In other words, the invention provides a practicable and relatively trouble-free means for reducing the exhaust gases of oxidizable contaminants into the atmosphere by converting the hydrocarbons, intermediate products of oxidation and carbon monoxide into, for example, carbon dioxide and water.

In the catalysts of the invention, the platinum group metals are oxidation promoters and are present in sufficient quantities to give the catalysts significant activity in catalyzing these reactions. The platinum group metals include, for example, platinum, ruthenium, palladium and rhodium, and mixtures of such metals can also serve as the platinum group metal in the catalyst. The amount of platinum group metal is a minor proportion of the catalyst and is generally no more than about 2 weight percent for economic considerations. For example, the amount can be about 0.01 to 2% and is preferably about 0.02 to 1%. If the metal of the platinum group of these catalysts consists of more than one metal of the platinum group, then this component can consist of a major amount of platinum and a smaller amount of one or more other metals of the platinum group, for example palladium. For example

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this component of the catalyst may be from about 60 to 95 wt -.% platinum and about 5 to 40 wt -.% palladium exist. The platinum and palladium are preferably present when they are used for the preparation of the catalysts according to the invention in the form of the amine hydroxides or as platinum hydrochloric acid and palladium nitrate. The platinum group metal can be present in the catalysts in elemental or bonded form, for example as oxide, sulfide or the like, and the stated amounts of these metals relate to the metal present, regardless of the form in which it was used.

The catalysts according to the invention contain catalytically active forms of aluminum oxide and oxides of rare earth metals. The alumina can be a gamma alumina, e.g. Silica and the like. The amounts of aluminum oxide and oxide of a rare earth metal in the catalysts are sufficient to give the catalyst the necessary catalytic effect. Often, the amount of alumina is about 50 to 99 wt -.%, Preferably about 75 to 95 wt -.% _T while the amount of oxide of a metal of the rare earths from about 1 to 50 wt -.%, Preferably about 5 to 25 percent . -%, based on their total weight. The rare earth metal oxides used in the catalyst include those of lanthanum, samarium, praseodymium and the like, and this component is preferably cerium oxide. Mixtures of these oxides, for example mixtures in which the main component is cerium oxide, can also be used. The catalysts can also contain small amounts of other constituents, which may serve as promoters for the oxidations, for example manganese, vanadium, copper, iron, cobalt,

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Nickel and the like. These components include the various metal oxides and other compounds of metals.

During the calcination, the oxides are of the rare-earth metal and aluminum at temperatures of at least about 75O ⁰ C the oxides close to each other before and an excessive sintering of the aluminum oxide does not take place, but there is obtained a catalytically active product. The calcined mixture of finely divided alumina and oxide of a rare earth metal can be prepared, for example, by calcining a mixture of oxygen-containing compounds of rare earth metals and aluminum which decompose to their oxides as the calcination proceeds. These oxygen-containing compounds are precursors of the oxides and can be inorganic, ie they can be oxygen-containing metal salts which can be soluble in water. Preferably, an aqueous solution of a rare earth metal salt is mixed with finely divided alumina in hydrated or catalytically active form and the mixture is calcined to form the mixed oxides. The intimate mixture of rare earth metal oxide and alumina can also be obtained by mixing an aqueous solution of the rare earth oxide with macroparticles of alumina such as alumina spheres. The mixture is then calcined to provide at least the outer portion of the macroparticles of alumina with the calcined mixture of rare earth metal oxide and alumina. Suitable CaIcinierungsbedingungen temperatures of at least about 75O ⁰ C, preferably about 900 to 1300 ⁰ C. The CaIcinierungsbedingungen are such that catalytically active solids with a relatively large surface, for example at least about 25 and preferably at least about 75 m / g, are obtained. This calcination is preferably carried out while the alumina and the oxide des

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Rare earth metal without support and in free flowing Condition. However, calcination can also take place after the mixture is applied to a support, if this is desirable. In any case, this calcination is carried out before the platinum group metal, which is an essential Component is added.

The catalyst according to the invention can be prepared, for example, in such a way that an aqueous up-? slurry of the calcined mixture of aluminum oxide and oxide of a rare earth metal is brought into contact with the catalytically relatively inert support. The rare earth metals and aluminum are present in the slurry in the form of oxides or other substantially water-insoluble forms which are converted to oxides under the conditions of subsequent calcination. The solids of the slurry deposit on the support and the resulting mixture is dried or at a temperature at which a catalytically active product, which may be a catalyst of the type known from US Pat. No. 3,565,830, is formed, calcinier.t. The heating temperatures are not so high that the mixture of rare earth oxides and aluminum is sintered too much. Rather, the coating on the support after calcination has a surface area of at least about 25 m / g, preferably at least about 75 m / g. Suitable calcination temperatures are generally at least about JOO ⁰ C and can be up to about 700T. Temperatures of approximately 400 to 600 ^° C. are preferred; however, lower temperatures can also be used to dry the masses.

After the coated carrier is dried or calcined, the mass becomes that of a platinum group metal existing component added to increase the catalytic activity of the mass. The platinum group metal can the coated carrier in any desired one

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Way to be added. In general, the mass can with a aqueous or other solution of this component impregnated or this component can be used in another way on the with the coating provided carrier are deposited. For example, the platinum group metal can be in the form of an acidic solution of for example platinum hydrochloric acid are added, or the platinum group metal can be incorporated into the coated carrier in the form of other ions. If desired, the platinum group metal can be obtained from a solution for example in the form of a sulphide by contact with hydrogen sulphide, may be precipitated, and during the subsequent Calcination or use, the platinum group metal can be converted into the elemental form. Preferably the elemental metal is in very fine particle size, for example in the form of particles below about 50%.

After the addition of the metal of the platinum group, the catalyst is dried and then alined under conditions in which properties which promote oxidations are imparted to the mass. Calcination can have the advantage of stabilizing the catalyst so that the activity of the catalyst is not significantly altered during the initial stages of its use. The Galcinierung, for example, at temperatures of at least about 300 ⁰ C up to about 700 ⁰ C or above, preferably about 400 to 600 ° C, are carried out. The dried or calcined catalyst has a considerable surface area of, for example

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at least about 25 m / g, preferably at least about 75 m / g, based on the weight of the rare earth oxide and aluminum oxide coating on the support, while the relative inert catalyst supports have a relatively small surface area, often below about 10 or even below about 1 m / g Has carrier. The surfaces given below are determined according to BET or a similar method.

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An alternative method for preparing the catalysts according to the invention is that the metal of the Platinum group is added to the calcined mixture of the oxide of the rare earth metal and aluminum oxide before

· "Ta

the latter is deposited on the relatively inert support - if this form of catalyst is to be produced. For example, in preparing a catalyst having a relatively inert support, an aqueous slurry of the calcined mixture of oxides can be prepared and the platinum group metal component added to the slurry in a water-soluble form and intimately mixed therewith. The component of the metal of the platinum group can be in acid form, for example as platinum hydrochloric acid, or in another ionic form, as described above, and can be deposited on the precalcined oxides, for example by adding hydrogen sulfide. The mixture containing the platinum group metal can be dried or calcined to give a platinum group metal and rare earth metal oxides and aluminum in a form in which they are better suited for deposition on the relatively inert catalyst support or for use as such as a catalyst in finely dispersed form or in the form of macroparticles suitable to form material containing. The calcination may preferably be carried out at about 400 to 600 ⁰ C at temperatures of at least about 300 "C up to about 700 ⁰ C or above. The calcination is not carried out under conditions so severe that the catalytic activity of the composite is undesirably reduced, and the calcined material generally has a surface

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of at least about 25 m / g, preferably at least about 75 m / g.

The resulting calcined material can be on the relatively inert support in the above for the deposition of the calcined Oxides that do not have to contain the metal of the platinum group are deposited in the manner described. The one provided with the coating Support can also be dried and, if desired, calcined

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as above for drying and calcining the catalysts, that by adding the metal of the platinum group to which the calcined mixture of oxides of metals of the rare Earth and aluminum oxide are described.

The relatively inert supports which can be used to prepare the catalysts of the invention can be made from a wide variety of materials, but preferably consist primarily of refractory metal oxide. Although the catalyst supports and thus the catalysts according to the invention preferably have a uniform skeletal structure of relatively large dimensions, for example in the form of a honeycomb, the catalysts can also be in the form of smaller particles, for example with a smallest dimension of at least about 0.4 mm (1 / 64 "). In any event, such catalyst particles can be referred to as macroparticles because they are considerably larger than the particles of finely divided catalysts, for example those used in fluidized bed reactions. Catalysts according to the invention are in the form of macroparticles often 0.4 to 12.7 mm (1/64 to 1/2 "), preferably 0.8 to 6.35 mm (1/32 to 1/4"), and when not spherical , Lengths from about 0.4 to 25.4 mm (1/64 to 1 ") or. above, preferably about 0.8 to 6.35 mm (1/32 to 1/4 "). For their use in a chemical reaction, these particles are often placed in the form of beds in the reaction zone. The calcined mixture of alumina and oxide of a rare earth metal often forms a small proportion of the catalyst structure, but is present in sufficient amount to impart a catalytic effect to the catalyst, for example in an amount of about 2 to 30% by weight , preferably about 5 to 20% . <.

These catalysts are preferably unitary, i.e. have a unitary or monolithic solid refractory

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Skeletal structure. The skeletal structure can be cylindrical, must but not necessarily have a circular cross-section and can have pores in its inner part and also surface pores and / or perforations associated with the Skeletal structure extending gas flow channels are connected, can be present. The channels can be of the most varied Have shapes and cross-sections. The activated material located on the carrier can be a mixture of one Oxide of a rare earth metal and a gamma aluminum oxide or activated alumina and can be on the surface of gas flow channels and also on the surfaces of the surface pores communicating with these channels. The ones made from the metal of the platinum group existing component is made of the activated one consisting of oxide of a rare earth metal and aluminum oxide Material carried and contains a single platinum group metal or a combination of such metals.

The catalyst carriers with a uniform skeleton structure can be in honeycomb form and are characterized by that they have a plurality of flow channels or paths extending in the general direction of gas flow through the Carriers extend, have. During use, the catalyst is usually placed in a container in such a way that that its uniform skeletal structure occupies the main part of the cross-sectional area of the reaction zone. With advantage is the unitary skeletal structure shaped to fit into the reaction zone in which it is to be placed is, and the unitary catalyst with the support can be arranged in the reaction zone so that its cellular Gas flow channels extend longitudinally, i.e. the channels extend in the direction of gas flow between the inlet and outlet so that the gases during their Passage through the container through these channels. The flow channels do not have to run straight through the catalyst structure extend and can flow deflectors or spoilers contain.

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The relatively inert carriers of the catalysts according to the invention preferably consist of a substantially chemically and catalytically relatively inert rigid solid material which maintain at high temperatures, for example up to about 1100 ⁰ C or even up to about 18oo ° C or above its shape and strength able. The carrier can have a low coefficient of thermal expansion, good thermal shock resistance and low thermal conductivity. Often the carrier is porous; however, its surface can be relatively non-porous and it may be desirable to roughen its surfaces to better hold the catalyst, particularly if the support is relatively non-porous. The carrier can be a metallic or ceramic carrier or a combination thereof. The preferred supports, both skeletal and other shaped supports, are made of cordierite, cordierite / alpha alumina, silicon nitride, zirconium / mullite, spodumene, alumina / silica / magnesia or zirconium silicate. Examples of other refractory ceramic materials that can be used as supports in place of the preferred materials are SiMmanite, magnesium silicates, zirconium, petalite, alpha alumina and aluminosilicates. Although the support can be made of glass-ceramic, it is preferably not glazed and can be essentially completely crystalline and characterized by the absence of a significant amount of vitreous or amorphous phase such as is found in porcelain materials, for example. In addition, the structure can have a considerable accessible porosity compared to the practically non-porous porcelain which is used for electrical applications, for example in spark plugs, and which is characterized by a relatively low accessible porosity. The structure can have a water pore volume · of at least about 10 #. The walls of the channels of the unitary skeletal support structure can have a plurality of surface macropores which are in communication with the channels so that the

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accessible catalyst surface is considerably increased, and thus a good high temperature stability and strength is achieved, small pores can be virtually absent. Such supports are disclosed in U.S. Patent 3,565 described.

The geometric surface of the skeletal type beams, including the walls of the gas flow channels is often about 0.5 to 6, preferably 1 to 5 m per liter of carrier, Die Channels leading through the unitary support or the skeletal structure can be of any shape and size compatible with the desired surface area is consistent, and should be large enough to allow a relatively free passage of the To enable implementation of the underlying gas mixture. The channels can be parallel or generally parallel and extend through the carrier from its one side to an opposite side and through preferably thin ones Walls to be separated from each other. The channels can also run in many directions and can also go with an or several adjacent channels are in communication. The channel inlet openings can be over the entire front surface or the be distributed over the entire cross section of the carrier so that they come into contact with the gas to be converted.

The gas flow channels of the unitary skeleton support catalyst can be thin-walled channels that present a relatively large surface area. The channels can be the same or have different cross-sectional shapes and sizes. The cross-section of the channels can, for example, be trapezoidal, rectangular, square, sinusoidal or circular, and the cross-sections of the beam can be a repeating one Pattern that appears as honeycomb, wavy, or lattice-shaped can be described have. The walls of the cellular channels are generally as thick as necessary to allow the uniform body has sufficient strength, and

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the thickness of these walls is often in the range of about 0.05 up to 0.25 mm (about 2 to 10 mils). At this wall thickness, the structures can have approximately 100 to 2500 or more gas inlet openings

for the flow channels each 6.5 cm cross-sectional area and one corresponding number of gas flow channels, preferably about 150 Contains up to 500 gas inlets and flow channels, each 6.5 cm. The open area of the cross-sectional area can be more than 60 # of the Total area. Size and dimensions of the unitary heat-resistant skeletal support according to the invention can vary, and the length of the flow channels is often at least about 2.5 mm (about 0.1 inch) or at least about 2.5 cm (about 1 inch) »

The catalysts of the invention can be used to accelerate the oxidation of various chemical feedstocks through contact with molecular oxygen. Some oxidations can take place at a relatively low temperature. However, oxidations are often carried out at elevated temperatures of, for example, at least about 150 ^° C., preferably about 200 to 900 ^° C., and the feed material is generally in the vapor phase. The feed materials are those which are susceptible to oxidation. They contain carbon and can be both organic and inorganic. That is, the catalysts can be used for the oxidation of hydrocarbons, oxygen-containing organic components, carbon monoxide and the like. Such materials can be present in exhaust gases from the combustion of carbon-containing fuels, and so can the catalysts in accordance with the invention can therefore be used for the oxidation of such exhaust gases or in the form of air or in any other desired form

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larger or smaller oxygen concentration can be added, are oxidized. The weight ratio of Oxygen to carbon in the oxidation products is greater than in the oxidized feed. Many such reaction systems are known.

The following examples illustrate the invention. Data in parts and percent relate to weight, unless otherwise stated.

Example I.

A stabilized Ce0 ₂ -Al ₂ 0 -, - mixture (slip) is prepared by dissolving 336 g of Ce (NO ₃ U.6H ₂ O in II88 ml of H ₃ O, so that about 1390 ml of solution are obtained. 1200 g activated AlgO-z powder is stirred into the solution, which is dried with constant stirring, transferred to a drying oven at 110 ^° C. and dried for 17 hours The dried solids are ground to a size below 0.42 mm (40 mesh) and calcined for 1 hour at 1100 ^° C. 1000 g of this calcined powder are _{mixed with 1000 ml of H 2} O and 20.1 ml of concentrated HNO and for 17 hours in a ball mill at 68 rpm in a 3.8 l container (US Stoneware 1000 parts of the mixture thus obtained are diluted with a solution of 3 * 3 parts of concentrated HNO and 333 parts of H ₀ O. A 50 cnr (3 cubic inch) cordierite honeycomb

· ₂

With about 250 parallel gas passages each 6.5 cm cross-sectional area, the mixture is dipped into this dilute mixture, ^{dried with air by blowing for 2 hours at 110 °} C. and calcined for 2 hours at 500 ^{° C.} About I3 to 14 wt -.% Of the total ceria and alumina adhere to the honeycomb. Platinum is added to this catalyst by the following procedure. To 1245 ml of aqueous KgPtCl ^ solution (platinum content 3.55 g) were added 3.05 g of NaHCO ^. 1.5 g Nacho ₂ of the solution was added at 95 ⁰ C. The honeycomb covered with cerium oxide and aluminum oxide is immersed in this solution, washed free of Cl,

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2 hours at 11O ⁰ C and calcined 2 hours at 500 S ^1. The honeycomb produced as described contains 0.40 wt .- ^ Pt.

Example II

The catalyst is prepared according to the method of Example I, with the difference that platinum is deposited on the honeycomb covered with cerium oxide and aluminum oxide by introducing this into 500 ml of aqueous HpPtCl • (platinum content 2.41 g) for a few minutes and then Treated 1/4 hour with HpS. The honeycomb is washed free of chlorine and dried and then ^{heated in air up to 500 °} C. for 1 hour and then ^{kept at 500 °} C. for 2 hours. The catalyst contains 0.2 wt. # Platinum.

Example III

A honeycomb coated with a cerium oxide / aluminum oxide mass is produced as in Example I. The honeycomb provided with the coating is then dissolved in a solution containing both HpPtClg and Na ₂ PdCl ₂ , whose concentration is 8.8 g Pt or 4 , 4 g Pd per 100 ml volume of solution, contains, immersed. After standing for 10 minutes with multiple lifting and lowering of the honeycomb out of or into the solution, it is taken out of the solution and allowed to drain. It is then treated with gaseous hydrogen sulfide for 15 minutes and washed free of chlorine with deionized water. The impregnated honeycomb obtained in this way is ^{dried at 110 ° C. overnight and calcined at 500 °} C. for 2 hours in a stream of air. The finished catalyst contains 0.21 wt -.% Pt and 0.11 wt .- ^ Pd.

Example IV

A Ceriuraoxid / alumina mass is prepared by mixing 841 g of Ce (N0 ₅ U.6H ₂ 0 ml H ₂ O are dissolved in 2970, so that 3460 ml of solution are obtained. To this solution 3000 g

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activated aluminum oxide powder added. The slurry is dried under constant agitation, into a drying oven of 11O ⁰ C and then 16 hours. The dried Peststoffe are ground to a particle size under 0.42 mm (40 mesh) and calcined for 2 hours at 1100 ⁰ C. A solution of platinum tetramine hydroxide plus palladium tetramine hydroxide was added to 108 g of this powder. The total volume of the solution was 151 ml * and it contained 2.75 g Pt and 0.60 g Pd. The wet powder was mixed thoroughly and dried at 11OT for 2 1/2 hours. The entire 181 g of powder was transferred to the container of a ball mill jar (1 qt) and 188 g of balls plus 180 cm ^ H ₂ O plus 3.6 cm ⁵ concentrated ENT was added. The entire mass was then ground in the ball mill at 60 rpm for 16 hours. The slurry was poured out and then used to coat the same type of honeycomb as in Example I by the same procedure. The catalyst thus prepared contained by calcination at 500 ⁰ C 0.18 OFEW. -% Pt and 0.04 wt .- # Pd.

Example V. .

A calcined Ceriumoxld / alumina composition is prepared as in Example IV and then calcined at 1100 ⁰ C. The powder is ground in a ball mill with a solution of (NHII) ₂ Pt (SCN) and g dajin used to immerse a honeycomb as in Example I. The thus-impregnated honeycomb * is dried and then calcined at 500 ⁰ C. The calcined catalyst contains 0.28 wt .- ^ Pt.

Example VI

In order to illustrate the improved properties of the catalyst according to the invention as an oxidation catalyst for exhaust gases, Catalysts prepared according to the procedures of Examples I and IV were tested. In the test procedure was

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a gas at various temperatures with an hourly flow rate of 40,000 volumes in contact with led to the catalyst. The gas contained $ 3.0! Oxygen, 1.0Si carbon monoxide, 300 ppm ethylene, 10.0 $ carbon dioxide, 500 ppm Nitric oxide, the rest nitrogen. The gas was preheated to the catalyst temperature before entering the catalyst to increase certain value, and the one tested at each temperature Gaseous effluent was analyzed for its carbon monoxide and ethylene content. The values obtained were against the oxidation temperature measured approximately 6.4 mm (1/4 ") in front the catalyst applied. From a plot of the oxidation temperature against the amounts of carbon monoxide and ethylene in the drain were those for a 50% conversion of carbon monoxide in carbon dioxide and temperatures required for a 50 # conversion of ethylene to carbon dioxide and water certainly. These values are given in Table I together with those with a corresponding catalyst which did not contain ceria, listed.

TABLE I.

Composition wt .- ^ Oxide mixture Platinum as temperature for of the oxide mixture on the honeycomb metal, 50 ^ -ige conversion

Wt -.% Lung, ⁰ C

•
0 0.20 Pt CO ^C 2 ^H 4 12, 6th 0.26 Pt 275 275 12, 0.17
+ 0.04 Pt
Pd 215 250 13, 175 190

Cerium oxide /
75 # Al ₀ O,

Cerium oxide /
Al ₂ O ₃

These values show that the catalysts according to the invention are more active than a corresponding catalyst used as a coating on the carrier only aluminum oxide (batch 1) instead of CeOp.AIpO ,,

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produced by the method according to the invention (batches and 3).

Example VII

To 5000 g of activated alumina balls with a diameter of 2.5 cm (0.10 ") g in a solution of 1401 Ce (NO,), ν6H ₂ O in 5050 ml H ₂ O was added. After 16 hours of drying at 110 ⁰ C, the Balls calcined in air for 2 hours at 1000 ^° C. After cooling, 3500 g of the balls are sprayed with a solution containing 3 * 033 S Pt (as tetramine hydroxide) plus 1.517 g of Pd (as tetramine hydroxide) in 1400 ml of solution the coating provided spheres were 16 hours at 110 ⁰ C dried and then calcined for 2 hours in air at 500 ⁰ C the final catalyst contained 0.087 wt -..% Pt + O, O43 wt -.% Pd + 10 wt -.% CeO ₂ on alumina.

The activity of the catalyst has been reported in U.S. Government CVS 1975 "Cold Start" Auto Emission Test Rated. The results showed emissions of 0.12 g of hydrocarbons per 1.609 kilometers driven (per vehicle mile) and 1.3 g of CO per 1.609 driven kilometers Kilometre.

Example VIII

Aluminum oxide balls were impregnated with cerium nitrate solution, dried and calcined vd. e in Example VII. 3500 g of the cooled spheres were sprayed with a solution of platinum tetramine hydroxide (4.550 g Pt - total solution volume - 14OO ml) and then dried and calcined as in Example VII. The finished catalyst contained 0.13 wt. ^ Pt + 10 wt -.% CeO ₂ on alumina.

The activity of the catalyst has been reported in U.S. Government CVS 1975 "Cold Start" Auto Emission Test Rated. The results showed emissions of 0.14 g of hydrocarbons per 1.609 km driven and 0.7 g of CO per 1.609 km driven.

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Claims (3)

^{λ <} AUG 3 1373 Claims (1 \ Substance composition of essentially a catalytic relatively inert solid support with a coating a catalytically active calcined mixture of essentially catalytically active amounts of oxides of rare earths and alumina, this coating being a catalytically effective amount of one or more Contains platinum group metals and prior to the addition of the platinum group metal at a temperature of at least about 750 C has been calcined. 2. A composition of matter according to claim 1, characterized in that the mixture contains about 75 to 95 wt .-% Al ₂ O ₃ and about 5 to 25 wt .-% oxides of rare earth metals. 3. The composition of matter according to claim 2, characterized in that that the platinum group metal is platinum, palladium or a mixture thereof. 4. The composition of matter according to claim 1, characterized in that that the rare earth oxide is predominantly cerium oxide. 5. A composition according to claim 4, characterized in that the calcination was carried out at a temperature of about ⁰ C to 1300 9oo. 6. A composition of matter according to claim 5, characterized in that the metal of the platinum group is platinum, palladium or a Mixture of it, is. 7. The composition of matter according to claim 6, characterized in that that the mixture contains about 75 to 95% by weight of alumina and about 5 to 25% by weight of ceria. - 21 - 09808/1081 B-11O9 3LX 8. Substance composition according to claim 1, characterized in that the calcination was carried out at a temperature of about 900 to 1300 ° C. 9. A composition of matter according to claim 8, characterized in that the mixture contains about 75 to 95% by weight of aluminum oxide and about to 25% by weight of rare earth oxide. 10. A process for the preparation of a "for use as a catalyst suitable composition, characterized in that an intimate mixture of finely divided aluminum oxide and oxide of rare earths to form a catalytically active mass of aluminum oxide and oxide of rare earths at a temperature of at least etv / a 75o ° C calcined, the mass forms a slurry in an aqueous liquid, a catalytically relatively inert solid support is provided with a coating of this slurry, the support provided with the coating is dried, a metal of the platinum group in aqueous solution is added to the coating on the support and drying the mass containing the platinum group metal. 11. The method according to claim 1o, characterized in that the oxide of rare earth metals predominantly cerium oxide is. 12. The method according to claim 11, characterized in that the mixture consists essentially of aluminum oxide and an inorganic one The salt of cerium, which decomposes to form cerium oxide. 13. The method according to claim 12, characterized in that the Platinum group metal is platinum, palladium or a mixture thereof. 14. The method according to claim 13, characterized in that the - 22 - ■ 4 09808/1081 B-11o9 7339513 Mixture contains about 75 to 95 weight percent alumina and about 5 to 25 weight percent ceria. ί5. Process according to Claim 12, characterized in that the calcination at e;
is carried out. Calcination at a temperature of about 900-1300 ° C 16. The method according to claim 15, characterized in that the The salt of a rare earth metal is cerium nitrate. 17. A method for producing a composition of matter suitable for use as a catalyst, characterized in that that you get an intimate mixture of alumina and rare earth oxide to form a catalytic active mass of alumina and rare earth oxide calcined at a temperature of at least about 75o C, the calcined material adds a metal of the platinum group in aqueous solution and that containing the metal of the platinum group Mass dries. 18. The method according to claim 17, characterized in that the calcine:
he follows. Calcination at a temperature of about 900 to 1300 C. 19. The method according to claim 18, characterized in that the Mixture contains about 75 to 95% by weight of aluminum oxide and about 5 to 25% by weight of rare earth oxide. 20. The method according to claim 19, characterized in that the Rare earth oxide is predominantly cerium oxide. 21. The method according to claim 17, characterized in that the hatches of aluminum oxide, rare earth oxide and metal Platinum group in the form of an aqueous slurry is used to make a catalytically relatively inert to provide a solid support with a coating, after which the coated support is dried. 40 9 8 08 / fO81 7339513 22. The method according to claim 21, characterized in that the Calcinii
he follows. Calcination at a temperature of about 900-1300 ° C 23. Substance composition of essentially a catalytic active calcined mixture of an oxide of a rare earth metal and aluminum oxide and a catalytically active one Amount of a platinum group metal, the mixture being prior to the addition of the platinum group metal at a temperature was calcined at least about 75oC. 24. Substance composition according to claim 23, characterized in that that the calcination was carried out at a temperature of about 900 to 1300 ° C. 25. A composition of matter according to claim 24, characterized in that that the mixture contains about 75 to 95 wt .-% alumina and about 5 to 25 wt .-% rare earth oxide. 26. Substance composition according to claim 25, characterized in that that the rare earth oxide is predominantly cerium oxide. 27. A method for oxidizing a carbonaceous material, characterized in that iijan this material in gaseous form oxidized by contact with oxygen and the catalyst composition of claim 1. 28. The method according to claim 27, characterized in that the carbonaceous material is the exhaust gas from the combustion of a hydrocarbon fuel. 29. Process for "oxidizing a carbonaceous material, characterized in that the material is in gaseous form by contact with oxygen and the catalyst composition of Claim 8 oxidized. - 24 - /, 09808/1081 30. The method according to claim 29, characterized in that the Material is an exhaust gas from the combustion of a hydrocarbon fuel. 31. A method for oxidizing a carbonaceous material, characterized in that the material is in gaseous form Contact with oxygen and the catalyst composition of claim 23 is oxidized. 32. The method according to claim 31, characterized in that the carbonaceous material is an exhaust gas from the combustion of a hydrocarbon fuel. 33. A method for oxidizing a carbonaceous material, characterized in that the material is in gaseous form Contact with oxygen and the catalyst composition of claim 26 is oxidized. 34. The method according to claim 33, characterized in that the material is an exhaust gas from the combustion of a hydrocarbon fuel is. - 25 409808/1081