Title of Invention

"AN IMPROVED AUTO EXHAUST EMISSION CONTROL CATALYTIC CONVERTOR"

Abstract

An improved autoexhaust emission control catalytic converter which comprises a body (9) having an inlet & outlet (10,11), a heat shield (15) is provided to cover entire area of the said body (9), characterized in that the said body (9) is containing a honeycomb monolith alumina wash coated and catalyst coated ceramic substrate (12), the said substrate having channel density in the range of 100-500 channels per square inch, the said substrate is insulated by a mat (13) which is supported by packing material (14) .

Full Text

This invention relates to an improved auto-exhaust emission control catalytic converter useful for control of emissions from petrol engine exhaust. The device of the present invention can be fitted to petrol driven engine which is either stationary or installed in a vehicle for the reduction of carbonmonoxide and hydrocarbons gas emissions. A petrol driven engine exhaust emissions comprise of carbonmonoxide (CO), hydrocarbons (HCs), nitrogen-oxides (NOx) as major components along with particulate matter, sulphur-dioxide etc. The air pollutants emitted by vehicles have severe impact on air quality. The rise in the level of carbonmonoxide (CO), hydrocarbons (HCs) and other pollutants from exhaust emissions lead to adverse impact on human health as carbonmonoxide is a poisonous gas", whereas hydrocarbons are known carcinogens. Therefore, it is necessary to control CO and HCs emissions. The technological options viz. thermal reactor, exhaust gas recirculation and engine modifications applied to control autoexhaust emissions have certain difficulties in application and operations. The catalytic converter has been proved an effective device for auto-exhaust emission control. There are two types of oxidative catalytic converters viz, noble metal and non-noble metal based. The non-noble metal based catalytic converters used to oxidize carbonmonoxide and hydrocarbon to carbon dioxide and water; mainly employ the catalyst of different types viz; base metals, mixed oxides, zeolites, perovskites etc. ~ Reference may be made to, "Oxidation of CO and C2H4 by base metal catalyst prepared on honeycomb supports" by J.T. Kummer, scientific research staff, Ford Motor Co., Dearborn Mich. Published in "Catalysts for the Control of Automotive Pollutants" by American Chemical Society (1975, pp.178). The preparation and testing of small honeycomb catalyst with Co3O4 and copper chrornite as the active phase for oxidation of CO and C2H4 as described herein and given in the reference. The ceramic honeycomb substrate was washcoated with colloidal zerconia to produce washcoat loading of 20-25% by weight of substrate. The washcoated substrate was heated at 815°C for 24 hrs before catalyst coating. The substrate was immersed in cobalt nitrate solution, and the excess was blown out of the passageways with compressed air. Anhydrous ammonia was blown through the honeycomb to precipitate cobalt hydroxide, and the honeycomb was dried with a hot air gun,. The honeycomb was then heated at 315°, 649°, or 815°C for 24 hrs. The activity of catalytic converter was tested using synthetic exhaust prepared by mixing pure gases. The reactor volume was based on the space velocity of 70000/hr. The catalytic converter was also tested on vehicle engine exhaust for average space velocity of approximately 60000/hr. Light-off temperature was reported as 260°C for 50% conversion of CO and HCs at a space velocity of 80000/hr. No consideration was given to pressure drop across the catalytic converter. Performance was not evaluated for conversion efficiency on predetermined driving cycle which make it unable to predict the performance of catalytic converter on road conditions. Severe effect of sulphur dioxide content on conversion efficiency has also been reported for cobalt oxide catalyst. The United States patent number 4919902 describes a catalytic composite for treating exhaust gas comprising a support which is refractory inorganic oxide having dispersed thereon lanthanum, at least one other rare earth component and at least one noble metal component selected from the group consisting of platinum, palladium, rhodium, ruthenium and iridium. An essential feature of said catalytic composite is that the lanthanum be present as crystalline particles of lanthanum-oxide which have an average crystal size of less than about 25 Angstroms. The support may be selected from the group consisting of alumina, silica, titania, zirconia, aluminosilicates and mixture thereof with alumina being preferred. The rare earth components are at least one from cerium, neodymium, praseodymium, dysprosium, europium, holmium and yttrium. In a preferred embodiment of the US patent no. 4919902 lanthanum may be dispersed on alumina as follows : a solution of lanthanum salt is mixed with a hydrosol of aluminium, particles are formed from said lanthanum containing hydrosol, calcined to form an inorganic oxide particle containing lanthanum oxide, grinded to give a powder of alumina containing finely dispersed lanthanum oxide. This powder in turn can be mixed with another rare earth oxide such as cerium oxide, a slurry which in turn is used to coat a solid monolithic carrier. Finally at least one noble metal component is dispersed on said coated solid monolithic carrier. Reference may be made to, " Perovskite Oxides : Materials Science in Catalysis", by R.J.H. Voorhoeve, D.W. Johnson, Jr., J.P. Remeika and P.K. Gallagher, published in "SCIENCE", 4 March 1977, Volume 195, Number 4281 (pp 827). The authors have described the use of perovskite type catalysts for autoexhaust applications. Various ABO3 structured perovskite type catalysts have been discussed. Perovskite has been reported to be resistant to the chemical poisoning by lead (Pb). Substitution of small amount of platinum (Pt) in perovskite structure has shown the reduction in poisoning by sulphur. The perovskite catalyst was not claimed commercially successful catalyst for auto exhaust applications. In our co-pending Indian patent application No.961/DEL/93 we have described and claimed an improved device for the removal of pollutants from autoexhaust as shown in Fig. 1. of drawings accompanying this specification. This device comprises a main body(4), provided with an inlet(1) and an outlet(2), a plenum d^sc(3), provided with holes provided at the inlet portion, the disc being provided with flanges(6), the main body housing a series of supports, containing * the catalyst capable of reducing the pollutants present in the exhaust gases(5). The device may be made of metals usually employed for the above purpose. The different parts of the device such as the inlet/outlet portions and the main body may be made and attached in such a way, that these parts can be separated and reassembled as per the requirements. The portions between the main body and the inlet and the outlet may be in the form of conical shape. Such an arrangement helps in the proper distribution of the gases which enter the main body. This device was claimed to be useful for the conversion of CO and HCs present in the exhaust gases. In a preferred embodiment of the co-pending patent application No. 960/DEL/93, the reported catalytic converter consist of ceramic monolith supports prepared by compression moulding technique. The process of producing ceramic monolith support is disclosed in copending patent application No. 959/DEL/93. The device useful to produce the ceramic support for the said use is described in co-pending patent application No. 958/DEL/93. The preferred catalyst employed in the device is perovskite catalyst. The method of catalyst synthesis and procedure of catalyst coating on ceramic support are disclosed in copending patent applications No. 960/DEL/93. The catalyst has the general formula La,.,,, Pbx ( Mn,.y O3 and La Pbx Coy O3 Where x represents 0.1-0.7 and y represents 0.05-0.15 The device disclosed in patent application no. 960/DEL/93 was claimed to have reduction in CO and HCs to a range of 50-60% under the exhaust conditions. The active life claimed was about 15000 kms. This device has certain drawbacks. The ceramic support used in the above described device was prepared by compression moulding technique. The geometrical specifications such as number of channels per square inch and length of support are not sufficient to provide the large geometrical area of catalyst support required for this application. The available small open frontal area is causing the pressure drop at the inlet and outlet surfaces of ceramic supports. The -high material density of ceramic supports used, poses two problems viz; increased weight of catalytic converter and delayed light-off. Low specific surface area of compression moulded ceramic support is also one of the limitations. The reactor design is not compact and no proper heat dissipation device is employed. The main objective of the present invention is to provide an improved autoexhaust emission control catalytic converter which overcomes the above mentioned drawbacks. The improved device of the present invention comprises of ceramic honeycomb monolith substrate. The substrate is having channel density in the range of 100-500 channels per square inch. The substrate is washcoated with alumina slurry followed by ceria precoat. Alternatively ceria is blended in alumina slurry before washcoating. The washcoated substrate is coated with finely divided perovskite type of oxidation catalyst . The catalyst coated substrate is then doped with noble metal promoters. The catalyst coated and promoter metal doped ceramic substrate is enclosed in metallic housing with proper insulation mat, wrapped over the substrate. A heat shield is provided to dissipate the excess heat and to protect under-body heating of vehicle. The efficiency of the device ranges from 50-60% for CO and 70-85% for HCs oxidation depending on various operating conditions of the engine and space velocity. The embodiment of the improved device of the present invention is shown in Fig. 2 (a & b) and Fig. 3 (a & b) of the drawings accompanying this specification. Accordingly the present invention provides an improved autoexhaust emission control catalytic converter which comprises a body (9) having an inlet & outlet (10,11), a heat shield (15) is provided to cover entire area of the said body (9), characterized in that the said body (9) is containing a honeycomb monolith alumina wash coated and catalyst coated ceramic substrate (12), the said substrate optionally coated with promoter metal such as herein described, the said substrate having channel density in the range of 100-500 channels per square inch, the said substrate is insulated by a mat (13) which is supported by packing material (14) such as herein described. According to another feature of the invention the honeycomb monolith alumina wash coated ceramic substrate having channel density preferably in the range of 100-500 channels per square inch. The material used fro the insulation mat is selected from vermiculite blended ceramic fiber mats and similar materials. The substrate may be optionally coated with prometer metal consisting of platinum in the range of 0.03 to 0.10 wt% of the substrate weight. The geometry of the catalyst coated ceramic substrate (12) may be such as to provide sufficient volume for oxidation reaction based on the volume of exhaust gas to be treated. The body (9) of device can be made of austenitic and ferritic stainless steel such as type 321, 409, 304 or 316-L metals or cold rolled galvanized mild steel metal or any other suitable materials which are usually employed for such purposes. The substrate is made up of ceramic of cordierite or alumina or combination of cordierite and alumina, having the honeycomb type structure, with channel density of 100 to 500 channels per square inch. The insulation mat may be made up of ceramic wool blended with zirconia or vermiculite or any other suitable material generally used for the purpose. The alumina used for washcoating is high specific surface area alumina, mainly gamma alumina (y-alumina) or its precursor. The slurry of alumina is prepared by either of the two methods. In method one; 10 to 20% by weight alumina, 15 to 30% by weight 1 N HNO3 and 50 to 75% by weight water were mixed. The resulting pH of the mixture was about 2 to 5. The mixture was then heated in a closed vessel at 70 to 90°C with continuous stirring for about 0.5 to 2 hrs. Cerium oxide was added in proportion 5 to 10% by weight of alumina. The BaO or La2O3 or combination of BaO and La2O3 was added in finely divided form and 2 to 3% by weight of alumina. The slurry thus obtained was then treated in high speed blender for 15 to 45 minutes so as to reduce the particle size. The viscosity of resulting slurry was controlled by percentage solids, acid content, temperature and treatment duration. Alternatively in Method two; alumina slurry was prepared by mixing 30 to 50% by weight alumina, 1 to 4% concentrated nitric acid and 46 to 69% water. Cerium oxide was added in proportion 5 to 10% by weight of alumina. The resulted mixture was then finely grinded using ball mill, preferably planetary ball mill for 0.5 to 3 hrs. The percentage of acid depends upon the dispersibility of alumina. As highly dispersible is the alumina, lower the quantity of concentrated nitric acid is required. The major emphasis was given on the particle size reduction.The Ba or La2O3 or combination of BaO and La2O3 was added in finely divided form and 2 to 3% by weight of alumina. These stabilizers should be essentially in very finely divided form to prevent high temperature sintering of alumina particles. The alumina slurry prepared by either of the above described methods is then coated on ceramic monolith substrate. A special technique is applied to coat alumina slurry. Ceramic substrate is placed vertically in a closed vessel and vacuum is applied from open space above the alumina slurry, from top of vessel. This application of vacuum helps in removing the air trapped in pores and slurry can then flow into the pores. Partial vacuum is also applied after introducing slurry into coating vessel so as to remove any traces of air trapped. Alternatively, alumina slurry is coated on ceramic substrate by manually dipping it in alumina slurry for a short period. Excess slurry filled in the channels of ceramic substrate is removed by blowing compressed air through the channels. Alumina thus adhered on the surface of channels is dried by forced hot air at temperature 80 to 150°C through channels. The forced air drying helps in avoiding blocking of channels by alumina. The air-dried alumina washcoated substrate is then heated at temperatures upto 550 to 800°C for 4 to 8 hrs. The percentage loading achieved is in the range of 5 to 35% of the substrate weight. The catalyst used here is perovskite type of catalyst comprises of Lanthanum (La), Lead (Pb) (optional), Manganese (Mn), Cobalt (Co) and doped with Platinum (Pt). The general formula of catalyst is : Where, A is either Pb or Sr, B is either Mn or Co x represents 0.1-0.7 and y represents 0.05-0.15 Dis Pt Catalyst synthesis has been done following two methods, viz. in-situ synthesis or co-precipitation method. In the in-situ method, salt solutions of various salts are prepared separately and mixed together in stoichiometric proportions so as to obtain the catalyst with formula as explained above. Alumina washcoated substrate is dipped into cerium nitrate solution prepared by mixing 80 to 100 g of cerium nitrate in about 1000 ml of acetone. This cerium nitrate is then oxidized to cerium oxide by subsequent drying and furnace heating of coated substrate at 600°C for about 4 to 6 hrs. The ceria precoat helps in avoiding reaction between alumina and metal ions during catalyst formation. Ceria precoated substrate is then dipped in mixed metal salt solution for about 10 to 20 minutes. Excess solution is blown out by compressed air and substrate is oven dried. The dried substrate is then dipped in solution of Pt-chloride solution prepared in acetone so as to maintain the stiochiometric proportions in the formula explained above. The substrate coated with mixed metal salt solutions and Pt salt solution is heated at temperatures 850 to 900°C for 8 to 10 hrs. Alternatively the Pt solution can also be mixed in the mixed metal ions solution and can be soaked on ceramic substrate in a single step. In the co-precipitation method, salt solutions of various salts are prepared separately and mixed together in stiochiometric proportions except Pt salt. Mixed metal hydroxides are then precipitated by adding aqueous ammonia solution with continuous stirring. The precipitate obtained is kept for ageing for 8 to 10 hrs. The precipitate is then washed, dried in oven at 80 to 100°C and soaked into Pt-chloride solution prepared in acetone by maintaining the required stiochiometry. Precipitate is then heated at 850 to 900°C for 8 to 10 hrs following the slow heating cycle and intermittent grinding after 550°C. The perovskite thus obtained is finely grinded to submicron level', and coated on ceramic substrate by using vacuum coating method as explained in this specifications earlier. The catalyst coated substrate prepared by either of the in-situ or co-precipitation method was then diped into solution of Pt- or Pd-chloride or combination of Pt-chloride and Pd-chloride in acetone having noble metal concentration of about 400 to 500 ppm. The substrate is then dried and heated at about 600°C for 3 to 4 hrs to decompose Pt/Pd-chloride to metallic form. The substrate is then activated by heating in hydrogen atmosphere at 400 to 450°C for 3 to 4 hrs. The catalyst coated, noble metal promoted, activated support is then placed in metallic shell. In a preferred embodiment of the invention as shown in Fig.2 (a & b) and Fig. 3 (a & b) of the drawings, the body (9) may be of round shape, with one inlet (10) in conical or truncated shape and one outlet (11) in conical or truncated shape. The embodiment is constructed in such a way that the alumina washcoated and catalyst coated ceramic substrate (12) is placed after some free space at inlet (10). The ceramic substrate (12) is wrapped in insulation mat (13). The insulation mat (13) is protected by packing rings (14), so as to avoid contact of exhaust gases with insulation mat (13). Heat shield (15) which is provided to avoid underbody heating of vehicle is in cylindrical shape and placed in such way so as to cover the entire cylindrical length of main-body (9) and maintain same distance from main-body's outer surface. The device of the present invention works as follows : The exhaust gases from exhaust manifold enter through inlet pipe and pass through the ceramic honeycomb substrate. The reactants such as CO, HCs, and O2 travel through bulk flow of gas, to gas-solid interface in each channel. Then reactants travel through stationary interface by diffusion and get adsorbed on catalyst surface. Adsorbed reactants on active site of the catalyst react with each other and products thus formed then gets desorbed from surface and travel through gas solid interface by diffusion and then to bulk flow of gases in the direction of exhaust flow. The oxidation catalyst helps to convert CO and HCs to CO2 and water. Thus treated exhaust gas passes through the outlet of the device connected to the tail pipe of the engine exhaust system. The process of alumina, catalyst coating by particle size reduction to submicron level and using special vacuum application for coating is the novel process of this invention. By this method a higher loading of alumina and/or catalyst is achieved without loss of open frontal area of channels. This ensures the higher catalyst surface area and in turn better performance even at higher temperatures. This also helps in achieving lower pressure drop and better durability. Optimum use of noble metals in combination with perovskite to achieve catalyst stability & better light-off characteristics is also novel in this invention. The efficiency of the device for oxidation of CO and HCs varies for different test conditions. The converter was fitted to petrol driven engine on various vehicles and tested for idling emissions with and without converter. At warm idling conditions, converter shows 80-100% conversion efficiencies for CO and HCs oxidation. The converter was then fitted to petrol driven engine exhaust system on engine dynamometer and emissions before and after the converter were monitored for different speed and load conditions of engine. Conversion efficiency varies from 50% to 70% for different road-load conditions. The following examples are given to further illustrate the present invention and should not be construed to limit the scope of the present invention: Example 1 A ceramic honeycomb substrate made up of cordierite having 400 channels per square inch and approximately one litre volume was washcoated with y-alumina slurry. Alumina slurry was prepared by mixing 45 g of y-alumina and 124 ml of water and adding 76 ml of 1 N HNO3 followed by treatment at about 90°C temperature. The mixture was continuously stirred throughout the process. This alumina slurry was "treated in a high speed blender/attritor. The viscosity of slurry was controlled by percentage solids, pH conditions, temperature and treatment period. A special technique was applied to coat alumina slurry. Ceramic substrate is placed vertically in a closed vessel and vacuum was applied on open space above the alumina slurry, from top of vessel. This application of vacuum helps in removing air trapped in pores and, slurry can then flow into these micropores. Alternatively, alumina slurry is coated on ceramic substrate by manually dipping it in alumina slurry for a short period. Excess slurry is removed by blowing compressed air through the channels. Alumina -washcoated support is dried by forced hot air at temperature of 80 to 150°C. The forced air drying helps in avoiding blocking of channels by alumina during the water removal. After desired loading of y-alumina, the substrate was heated at about 600°C for about 4 hrs. The heat treatment is essential after each alumina coating to get a better adherence of alumina on ceramic support and to avoid peeling-off. The washcoated substrate was then characterized by BET surface area and scanning electron microscopic examination. The study shows that the specific surface area of about 25 m2/g of washcoated substrate was obtained. With the further loading of alumina, the specific surface area in the range of 30-45 m2/g could also be achieved. No significant loss of coating or surface area was observed when the washcoat adhesion test was performed on coated supports. Example 2 Alumina washcoated substrate was prepared by the method as explained in example 1. The alumina washcoated substrate was dipped in cerium nitrate solution prepared in acetone by dissolving 100 g of cerium nitrate in 1000 ml of acetone. The substrate was then dried and the procedure was repeated till 2 to 3 weight% loading of cerium nitrate was obtained. The substrate was then heated at 600°C for 4 hrs. The alumina washcoated ceria precoated substrate was then characterized for BET surface area. Specific surface area of 18-20 m2/g was obtained. Practically no loss of ceria, alumina or surface area was observed after the washcoat adhesion test performed on coated substrate. Example 3 Alumina slurry was prepared following the method as explained in example 1. 2.25 gm of finely divided cerium oxide and 0.5 gm of finely divided lanthanum oxide was added to alumina slurry before its treatment in high speed blender/attritor. The cerium oxide blended alumina slurry is then coated on ceramic supports following the method already explained. A uniform coating is obtained with specific surface area' of 22-33 m2/g. Higher specific surface area was also obtained with the further loading/coating of cerium-oxide blended alumina. No significant loss of surface area or coating was observed after the adhesion test on coated support was performed. Heat treatment after every alumina coating is preferred, to get better adherence on ceramic support. Example 4 An alumina washcoated and ceria precoated substrate was then coated with perovskite type catalyst which was synthesized using the procedure as follows : Various salt solutions were prepared separately by dissolving 35.03 gm, of lanthanum nitrate in 144 ml, of water, 11.482 gm of lead nitrate in 18.0 ml, of water and, 26.91 gm of manganese acetate in 75 ml of warm water. All the salt solutions were mixed together with constant stirring. The pH of this mixed solution was around 5.2. The warm mixed metal solution was then gently added with constant stirring into aqueous ammonium hydroxide solution containing 5% by volume of hydrogen peroxide. The strength of H2O2 should preferably be 30%. The precipitate thus obtained was kept for ageing for 8-10 hrs followed by filtration and washing. The powder was dried in oven and heated at 900°C for 8-10 hrs following a slow heating rate and with intermittent grinding of material. The catalyst was characterized for XRD and BETSA. An XRD pattern of perovskite synthesized is shown in Fig. 4. A catalyst slurry was prepared by milling the catalyst powder with water (around 20 weight % solid content) in a ball mill for 1 hr. The slurry rheology can be further improved by adding 0.6% methyl cellulose solution into aqueous slurry. This catalyst slurry is then coated on three numbers of alumina washcoated ceramic supports obtained one each by following methods described in examples 1 to 3 respectively. A uniform coating with desired catalyst loading (3-10 weight % of support weight) was achieved using the same coating technique as explained in example 1. These perovskite type catalyst coated supports were then promoted with platinum. A 100-250 ppm platinum solution was prepared by disolving the required quantity of chloroplatinic acid in acetone. The perovskite coated supports were dipped in platinum solution for five minutes and excess solution was blown out. The platinum incorporated substrates were dried in oven followed by heating at around 600°C for 3-4 hrs. The process of platinum loading was repeated till the desired loading (0.03-0.10 weight % of support weight) of platinum. These supports were then treated at around 500°C in a reducing (preferably in hydrogen atmosphere) for 2-3 hrs. The catalyst coated noble metal promoted supports thus obtained were designated as A,B and C respectively. Example 5 The catalyst coated supports as obtained in example 4 were then wrapped in insulation mat to prevent the thermal losses and to provide the cushioning effect. Vermiculite blended ceramic mat is a preferred material for the purpose. Commercially available insulation and packaging mat such as FIBRE FRAX™, XPE 2035™, Interam™, ceramic blanket may also be used. These supports wrapped in a mat are then'placed in a metallic reactor suitably made for the purpose. The catalytic converters thus prepared, were tested on laboratory evaluation assembly. In this test, the converter was placed in a tubular furnace and temperature was controlled by a linear temperature controller. Exhaust gas composition was simulated by mixing pure gases like CO, HCs, CO2, N2, O2 and NOx in required proportions and concentrations of CO, HCs and NOx were monitored before and after the converter at different temperatures. The space velocity was maintained at about 15000 hrs. Conversion efficiency for CO and HCs was observed in the range of 60 to 80%. The light-off temperature was in the range of 280-350°C. Prototype 'C shows comparatively higher conversion efficiencies than A and B. Example 6 The catalytic converter was prepared by using method as described for prototype B in example 4. The volume of catalytic converter was about 1.5 litre. The converter was fitted to a petrol driven engine with a capacity of about 1.5 litre, on an engine dynamometer. The concentrations of CO, HCs and NOx were monitored before and after the converter at different engine operating conditions. The conversion efficiency on road load conditions was estimated on the basis of these test results. The conversion efficiency estimated on road load conditions was about 50 to 60% for CO and about 50 to 65%. for HCs. Example 7 The catalytic converter was prepared by using the method as described for prototype C as detailed in example 4. The volume of the reactor was about 1.5 litre and this was tested on engine dynamometer following the method as described in example 6. The conversion efficiencies on road load conditions were predicted as 50-60% for CO and HCs conversion. Example 8 The catalyst was synthesized by 'following the procedure as described in example 4. This catalyst powder was then mixed with y-alumina in a ratio of 1:5 by weight and, the mixture was then treated in a ball mill with the addition of water to form a uniform slurry. This catalyst blended alumina slurry was then coated on a bare cordierite support following the coating procedures as explained. The coated support was-then oven dried and heated at around 600°C for 4-5 hrs. Desired loading-(15-25 weight% of the support weight) was achieved by repeated coatings. This catalyst coated support was designated as 'D'. Promoter metal was incorporated as explained in example 4 and canned in metallic shell as already described. This converter was tested in a laboratory evaluation assembly, maintaining the space velocity of around 15000 hrs"1' Conversion efficiency of 65-80% for CO and HCs were observed with a light-off temperature in the range of 250-350°C Example 9 A catalyst coated support was prepared by the method explained in example 8. However, catalyst : alumina ratio was maintained as 1:3 and this slurry was coated on an alumina and ceria washcoated support prepared by the method explained in example 3 and was designated as 'E1. This catalyst coated support was then promoted, activated and canned. The catalytic converters thus prepared, was tested on laboratory evaluation assembly. In this test, the converter was placed in a tubular furnace and temperature was controlled by a linear temperature controller. Exhaust gas composition was simulated by mixing pure gases like CO, HCs, CO2, N2, O2 and NOX in the required proportions. Concentrations of CO, HCs and NOx were monitored before and after the converter at different temperatures. The space velocity was maintained at about 15000 hrs"1. Conversion efficiency of 60-85% was observed for CO and HCs with a light-off temperature in the range of 250-300°C. Example 10 A perovskite type catalyst with the composition La0 8 Pb0 2 Pt0.os Mn0 g5O3, was synthesized. Various metal salt solutions were prepared separately by dissolving 26.795 g of lanthanum nitrate in 150 ml of water, 5.12 g of lead nitrate in 20 ml of water, 18.01 g of manganese acetate in 150 ml of warm water. All the aqueous metal ion solutions were mixed together. The warm mixed metal ion solution was then slowly added, with constant stirring, to aqueous ammonium hydroxide solution. The precipitate thus obtained was kept for ageing for 8-10 hrs followed by filtration, washing and oven drying. The dried precipitate was then soaked with 50 ml of platinum solution containing 1.132 of chloroplatinic acid with 40% platinum content. This platinum soaked precipitate was again dried in oven and heated at 900°C for 8-10 hrs following a slow heating rate and intermittent grinding of material. The catalyst so obtained was characterized for XRD and BET-SA. The catalyst was then coated on an alumina and ceria coated cordierite support obtained by the method described in example 3. The catalyst coating and promoter metal incorporation was done by following the method explained in example 4. The promoter metal (platinum) was maintained at 0.03-0.05 weight% of the support weight. The catalyst coated support was then canned in metallic shell. The catalytic converters thus prepared, are tested on laboratory evaluation assembly. In this test, the converter was placed in a tubular furnace and temperature was controlled by a linear temperature controller. Exhaust gas composition was simulated by mixing pure gases like CO, HCs, CO2, N2, O2 and • NOx in the required proportions. Concentrations of CO, HCs and NOx were monitored before and after the converter at different temperatures. The space velocity was maintained at about 15000 hrs"1. A conversion efficiency of 65-80% was observed for CO and HCs. This converter was also tested on engine dynamometer as discussed in example 6. The- conversion efficiencies observed were 50-65% for CO and 60-75% for HCs. The catalyst shows stable nature in respect of thermal and poisoning deactivation as shown by limited engine dynamometer tests carried out, using leaded petrol. Example 11 A converter was prepared following the method as described in example 10 except for the incorporation of promoter metal on catalyst coated support. This sample was designated as 'G'. The catalytic converters thus prepared, were tested on laboratory evaluation assembly. In this test, the converter was placed in a tubular furnace and temperature was controlled by a linear temperature controller. Exhaust gas composition was simulated by mixing pure gases like CO, HCs, CO2, N2, O2 and NOX in required proportions. Concentrations of CO, HCs and NOx were monitored before and after the converter at different temperatures. The space velocity was maintained at about 15000 hrs"1. Conversion efficiency of 50-70% was observed for CO and HCs. The light-off temperature observed was in the range of 300-375°C. The converter was also tested on engine dynamometer and the conversion efficiencies observed were in the range of 35-60% for CO and HCs. Example 12 Yet another manganate variety of perovskite type catalyst was synthesized with the following composition : La08 Sr02 MnO3 following the co-precipitation of metal salts in the form of hydroxides. After ageing and washing, the precipitate was soacked with chloroplatinic acid solution to incorporate platinum with the perovskite phase. The platinum concentration in perovskite was maintained at around 8000 ppm. The platinum soaked precipitate is again dried and finally heated at around 900°C for 8-10 hrs following a slow heating rate and intermittent grinding of material. The catalyst so obtained was then characterized and grinded to fine particles. This catalyst was coated on alumina and ceria coated cordierite support obtained by the method described in example 3. The catalyst coating and promoter metal incorporation was carried out by following the method as explained in example 4. The platinum loading was maintained at around 0.05 weight % of the support weight. This catalyst coated support was then reduced and canned as already explained. This converter was tested in the laboratory evaluation assembly and the conversion efficiencies observed were 65-75% for CO and 80-85% for the HCs. The converter was also tested on engine dynamometer and the conversion efficiencies observed were in the range of 60- 70% for CO and 60-75% for HCs. This catalyst also shows better thermal stability when tested on a test assembly following the inner thermal cycle (ITC) test procedure. Example 13 A cobaltate type of perovskite catalyst was synthesized with the composition La07 Sr03 Co095 Pt005 O3. The required amount of lanthanum nitrate, strontium nitrate and cobalt acetate were dissolved in distilled water. The * mixed metal ion solution was then gently added to aqueous ammonium carbonate solution with constant stirring. The precipitate thus obtained was washed and dried in oven. The dried precipitate was soaked with aqueous solution of chloroplatinic acid and the platinum soaked, precipitate was again oven dried and finally heated at around 900°C for 8-10 hrs following a slow heating rate and intermittent grinding of material. The catalyst so obtained was characterised for XRD and BET-SA. This catalyst was then coated on alumina and ceria coated cordierite support obtained by the method described in example 3. The catalyst coating and promoter metal incorporation was carried-out by following the method explained in example 4. The promoter metal loading was maintained at 0.03 weight% of the support weight. This catalyst coated and noble metal promoted support was then reduced in hydrogen atmosphere, and canned as already described. This converter was tested on laboratory evaluation assembly and the conversion efficiencies observed were in the range of 65-80% for CO and HCs. Advantages of Present Device The present device provides an improved autoexhaust catalytic converter using low-cost, non-noble metal based materials as a main catalyst/The device shows effective conversion of carbon monoxide and hydrocarbon pollutants. The device can be effectively used on a two-way or oxidative catalytic converter for mobile and stationery sources of these emissions having a gaoline based internal combustion engine. The- present catalytic converter is a low-cost substitute for nobel metal based converters, and shows better thermal stability and poison resistance. We Claim: 1. An improved autoexhaust emission control catalytic converter which comprises a body (9) having an inlet & outlet (10,11), a heat shield (15) is provided to cover entire area of the said body (9), characterized in that the said body (9) is containing a honeycomb monolith alumina wash coated and catalyst coated ceramic substrate (12), the said substrate optionally coated with promoter metal such as herein described, the said substrate having channel density in the range of 100-500 channels per square inch, the said substrate is insulated by a mat (13) which is supported by packing material (14) such as herein described. 2. An improved catalytic converter as claimed in claims 1 & 2 wherein the material used for insulation mat is selected from vermiculite blended ceramic fiber. 3. An improved auto-exhaust catalytic converter wherein the promoter metal consisting of platinum in the range of 0.03 to 0.1 wt% of the substrate weight. 4. An improved autoexaust emission control catalytic converter substantially as herein described with reference to the examples and figs 2&3 of the drawings accompanying this specification. We Claim: 1. An improved autoexhaust emission control catalytic converter which comprises a body (9) having an inlet & outlet (10,11), a heat shield (15) is provided to cover entire area of the said body (9), characterized in that the said body (9) is containing a honeycomb monolith alumina wash coated and catalyst coated ceramic substrate (12), the said substrate optionally coated with promoter metal such as herein described, the said substrate having channel density in the range of 100-500 channels per square inch, the said substrate is insulated by a mat (13) which is supported by packing material (14) such as herein described. 2. An improved catalytic converter as claimed in claims 1 & 2 wherein the material used for insulation mat is selected from vermiculite blended ceramic fiber. 3. An improved auto-exhaust catalytic converter wherein the promoter metal consisting of platinum in the range of 0.03 to 0.1 wt% of the substrate weight. 4. An improved autoexaust emission control catalytic converter substantially as herein described with reference to the examples and figs 2&3 of the drawings accompanying this specification.

Documents:

276-del-2000-abstract.pdf

276-del-2000-claims.pdf

276-del-2000-correspondence-others.pdf

276-del-2000-correspondence-po.pdf

276-del-2000-description (complete).pdf

276-del-2000-drawings.pdf

276-del-2000-form-1.pdf

276-del-2000-form-19.pdf

276-del-2000-form-2.pdf