METHOD AND APPARATUS FOR TREATING EXHAUST GASES OF AN INTERNAL COMBUSTION ENGINE

1371941 Purifying I C engine exhaust gases UNIVERSAL OIL PRODUCTS CO 16 Feb 1972 [19 Feb 1971] 7127/72 Heading F1B An I.C. engine exhaust gas purifying system comprises a catalyst bed providing a gas hourly space velocity (GHSV) at 15‹C and 1 atmosphere pressure of at least 50,000, the heat capacity of the system being less than 0À23 cal/‹C. The bed may consist of copper oxide assisted by oxides of iron, nickel, cobalt or vanadium on a carrier material, e.g. 2 to 30 wt per cent copper and 2 to 30% iron on an alumina support. Alternatively a noble metal such as platinum, palladium, ruthenium, rhodium, osmium or iridium may be used, e.g. 0À1 to 1À5% platinum on an alumina support. The bed may have a bulk density of 0À15 to 1À5 gm/cc. The system may be mounted immediately adjacent the engine exhaust manifold so that during normal running the temperature of the gas entering the catalyst bed is at least 480‹C. Secondary air may be added upstream of the bed such that the air proportion is up to three times that required to oxidize the oxidizable components. An additional copper containing catalyst bed may be provided downstream of the first bed to improve removal of nitrogen oxides. The system is said to be particularly effective immediately after cold starting of the engine. Dimensions of the bed are quoted.