INDUSTRIAL AND ENGINEERING CHEMISTRY
2396
Vol. 47, No. 11
that these same lead compounds are active catalysts in the engine and lend support to the generally accepted belief that leaded engine deposits glow or ignite more easily than unleaded deposits and, thus, are more likely to cause preignition. Lead compounds may also contribute to preignition by causing the deposit particles to burn more intensely and attain higher temperatures. Under these conditions, there is agreater possibility that the hotter particle will ignite the fuel-air mixture in the few milliseconds available for it t o do SO. The harmful effects of lead compounds in engine deposits may be nullified in two ways: I
additives. Of the 21 compounds investigated, only the two lead phosphates were found to be noncatalytic. Thus, on the basis of present information, if the preignition problem is to be solved or partially solved by the use of fuel additives which form deposits that do not ignite easily, compounds containing phosphorus would probably be most effective for this purpose,
1. Prevent the lead compounds, or carbon, or preferably both, from depositing in the combustion chamber. 2 . Convert the lead to some “harmless” or noncatalytic form by means of special fuel additives.
Campbell, J. M . (to General Motors Corp.), U. S.Patent 2,405,560 (1946). Jeffrey, R. E.,Griffith, L. W., Dunning, E., and Baldwin, B. S., Petroleum Refiner, 33, 92 (August 1954). Sabina, J. R., Mikita, J. J., and Campbell, 14. H., Proc. A m . Petroleum Inst., 33 (III), 137 (1953). \T7illiarns,R. I
