ISSN: 1546-962X
CODEN: JAIOAD
Page Count: 16

Phosphorus Additive Chemistry and Its Effects on the Phosphorus Volatility of Engine Oils

Selby, TW
Director of R&D, Savant, Inc., Midland, Michigan

Bosch, RJ
Technical Service Fellow and Process Improvement Specialist, Astaris LLC, Webster Groves, Missouri

Fee, DC
Technical Service Fellow and Process Improvement Specialist, Astaris LLC, Webster Groves, Missouri

(Received 9 November 2004; accepted 11 April 2005)

Abstract

The most widely used and effective anti-wear/anti-oxidation additives in engine oil contain phosphorus that can partially volatilize during engine operation. Unfortunately, volatile phosphorus in the exhaust stream degrades the function of the exhaust catalyst in reducing air pollution. Earlier studies in a special volatility bench test using the Phosphorus Emission Index have shown that phosphorus volatility is not related to engine oil volatility or to phosphorus content in the unused engine oil. At the time, it had been speculated that this unexpected lack of correlation with initial phosphorus concentration could be explained by 1) the effects of other engine oil additives and/or 2) variations in the phosphorus additive chemistry. The first speculation was relatively recently confirmed by taxi fleet studies of catalyst degradation by phosphorus-containing oils by the Ford Motor Company. It remained to determine if differences in phosphorus additive chemistry were also a factor, and this is the subject of the present study.

Keywords:
phosphorus volatility, Phosphorus Emission Index, PEI, ZDDP, zinc dithiophosphates, exhaust catalyst, exhaust emissions

Paper ID: JAI12977
DOI: 10.1520/JAI12977
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