• British Operator Tries Exhaust Cleaning
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rtA DEVICE claimed to eliminate dangerous exhaust fumes is being tested on six vehicles by a British fleet operator. It is called the Oxycat. It converts dangerous carbon monoxide into relatively harmless carbon dioxide, and hydrogen gases into water vapour.
The principle of operation is similar to the catalytic cracking process used in oil refineries. The Oxycat was invented by Mr. Eugene J. Houdry, who claims to be the originator of catalytic cracking.
The device consists of packs each of 72 porcelain rods of aerodynamic profile which are coated with a thin layer of a catalytic aluminium and platinum alloy. The rods are staggered in rows, so that the hot gases must flow
across their surface. They must be placed close together, because only the surface layer of the gas that is in contact with the rods is affected.
Hot gases passing over the rods cause a chemical reaction with the catalyst. This raises the temperature of the rods sufficiently for the reaction to continue even if the temperature of the gases is subsequently lower.
During the period of 10 to 15 minutes while the Oxycat is warming up, a high proportion of noxious gases escapes, but once the chemical reaction starts, the device stays at a red heat and the gases become harmless. It is claimed that the apparatus will reduce the carbon-monoxide content to below 0.01 per cent., a figure at which it has no physical effect.
The Oxycat has already found favour by recovering heat from flue gases by catalytic oxidation. Another successful application is the cleansing of waste effluents from industrial processes. In confined spaces, such as warehouses, garages, mines and so on, it is entirely effective on petrol-engined vehicles and
plant. A unit suitable for most vehicles, tractors and fork-lift trucks would at present cost about £70, plus installation charges.
If pollution of air in confined spaces can be completely avoided, this may not be considered an unreasonable figure. The only apparent shortcoming is the need to use unleaded fuel or white spirit. This factor is likely to prevent the general application of the Oxycat to road vehicles, as unleaded petrol is not usually available. Moreover, ignition timing would have to be altered in most cases if modified fuels were used.
When the device is applied to an oil engine, it is necessary to run the engine at full load in order to raise the temperature sufficiently (above 250° C.) to initiate the catalytic action. Efforts are being made to lower the operating
temperature required, by inserting stainless-steel plates between the rows of rods to conserve heat.
Reports that have appeared in Continental journals either imply or state that the apparatus reduces smoke and should help to relieve fog in large cities. This may be a false assumption. because the Oxycat cannot oxidize all the solids contained in the exhaust gases except at high temperatures, and it is these, in the form of carbon and soot, that appear as smoke.
Whilst an Oxycat operating on an engine consuming unleaded petrol will last for 2,000 hours or more, carbon deposits on the rods will soon destroy their effect. The need for proper maintenance of the engines is thus apparent, as oily constituents in the exhaust gases of petrol or oil engines would also be detrimental to the life of the apparatus. It is claimed, however, that should the unit become less active through contamination, it can be regenerated at lath:cost.
For general application to vehicles working in the open, the high price and need for unleaded fuel may make it impracticable.
Oxycats arc manufactured in the U.S.A. by Oxy-Catalyst Inc., and the sole agents in this country are OxyCatalyst, Ltd., 19 Berkeley Street, London, W. I, an associate of Powell Duffryn, Ltd. The British company's claims for the product when applied to internal-combustion engines are noticeably restrained compared with those made by overseas agents. J.S.