| 摘要 |
<p>Antiknock fuel additive compositions comprise organic P or As compounds together with organo-Pb compounds of the type PbR4 (R = alkyl or aryl, esp. ethyl or methyl) where the Pb/P (or As) atomic ratio is between 3/1.7 and 1/1, pref. 3/2 and 3/2.2. During combustion in a vehicle engine, the Pb compounds (having been used for their antiknock effects) are converted into phosphates Pb3 (PO4)2 or arsenates Pb (AsO4)2 of melting point 1000-1100 degrees C and a low volatility and are swept from the engine as a non-coherant microcrystalline powder which can be trapped by suitable filters in the exhaust system. Thus the Pb derivs. are neither deposited in the engine cylinders nor exhaust to the outside atmosphere- in fact the principal elements may be recovered from the filters for regeneration and re-use. The presence of halogenated compounds sometimes added to form volatile Pb compounds and purge the engine does not interfere. The non-acidic nature of the Pb and As additives allows Pb contents to be increased to improve engine performance without problems of corrosion or pollution.</p> |
