Patent GB-360024-A (GB)
Title: Improvements in method of eliminating combustible constituents from products of combustion of internal combustion engines
IPC: C01B32/50
Filed: 1930-07-31
Abstract: Combustible constituents are removed from the products of combustion of internal-combustion engines by subjecting such products, in the presence of oxygen, to the action of an artificially prepared metal chromite catalyst during intermittent operation of the engine. Chromites of metals of the sixth, seventh or eighth groups of the periodic system are particularly suitable; zinc chromite is also referred to.  The catalyst is preferably mounted on a carrier of heat conducting metal such as the copper nickel alloy known under the Registered Trade name "Monel metal" or high chromium <PICT:0360024/III/1> <PICT:0360024/III/2> <PICT:0360024/III/3> steels.  A suitable catalyst may be prepared by precipitating aqueous ferric nitrate with ammonia, adding sufficient chromic oxide to dissolve the ferric hydroxide precipitate, dipping metal carriers into the solution of ferric chromate and drying at about 110 DEG  C. The amount of chromic oxide employed is such that a chromite Fe2O3,3Cr2O3 is obtained.  The catalyst is preferably heated to a temperature of about 450 DEG  C. before starting by such means as electric resistance or arc heating, or by preheating the incoming air or products of combustion or both.  Oxygen may be added to the products of combustion in the form of air.  The process may be carried out in the apparatus shown in Figs. 1 and 2.  The products of combustion flow through a passage 10 into a tube 6 thereby drawing air through ports 4, chamber 3 in which it is pre-heated and nozzle 8. The resulting mixture of products of combustion and air flow through the catalyst 28 and discharges through outlet 12.  Cool air may also be admitted by ports 50 controlled by a shutter 51. The catalyst comprises iron chromite deposited on woven screens or slightly corrugated or perforated plates and may comprise, as shown in Fig. 3, a main body 41 separated by insulation 45 from an auxiliary portion 42, the latter being formed of electric heating resistance wires on which catalyst is also deposited arranged between concentric bands of insulation.  A spark plug 40 is also provided to heat the mixture of gases.  A conduit 16, Fig. 2, connects the inlet 10 to a resilient metal sylphon tube 15 whereby the pressure of the gases operate levers 18 and 22 and rotates a flange 24 and ring 25 connected to the nozzle 8.  A steep interior thread on the ring 25 engages an exterior thread on a sleeve 26 whereby the rotation of the flange 24 causes a longitudinal movement of the nozzle 8.  This movement regulates the amount of air admixed with the products of combustion in proportion to the pressure of the exhaust gases.  The volume of air mixed with the products of combustion is simultaneously regulated in proportion to the volume of combustible mixture fed to the engine, a rod 31, Fig. 2, which is connected to the accelerator control of an automobile operating the lever 18 through a cam 32 and roller 19.  The Specification as open to inspection under Sect. 91 (3) (a) comprises also the production of a suitable catalyst by oxidizing the surface of an iron-chromium alloy.  This subject-matter does not appear in the Specification as accepted.