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

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.

Neutral zinc(II) O,O‐di‐alkyldithiopho‐ sphates—variable temperature 31P NMR and quantum chemical study of the ZDDP monomer–dimer equilibrium

“…Current interest in ZDDP has included such topics as ligand exchange, [3,4] oxidation inhibition, [5] thermal film formation, [6] tribofilm formation, [7] antiwear properties, [8,9] friction properties, [10 -12] and interaction with other lubricating oil components. [13] Because of the need to replace ZDDPs partially or wholly by other phosphorus-free additives, [14] there is considerable interest in better understanding the chemistry of these materials.…”

Analysis of the Volatiles Generated During the Selby-Noack Test by 31P NMR Spectroscopy

“…Small samples of the original oils and the volatile materials and residues obtained during the Selby-Noack tests in the associated paper [1] were analyzed by 31 P NMR at Washington University (St. Louis, MO). The spectra were obtained either on a 500 MHz Varian NMR equipped with a 10 mm probe or on a 600 MHz Varian NMR equipped with a 5 mm probe.…”

A study on the chemical profile and the derived health effects of heavy-duty machinery aerosol with a focus on the impact of alternative fuels

“…We found that the main elements of the lubrication oil were calcium (Ca, 1710 mg kg −1 ), zinc (Zn, 1300 mg kg −1 ), and phosphorus (P, 1230 mg kg −1 , Table S6). These are typical additives used in lubrication oil (Selby et al 2005;Lin et al 2015). Ca is commonly used as a detergent additive, while Zn and P are used as extreme pressure-additives as well as wear protection additives (Selby et al 2005;Lin et al 2015).…”

“…These are typical additives used in lubrication oil (Selby et al 2005;Lin et al 2015). Ca is commonly used as a detergent additive, while Zn and P are used as extreme pressure-additives as well as wear protection additives (Selby et al 2005;Lin et al 2015). Other abundant elements found in the lubrication oil were boron (B, 310 mg kg −1 ), followed by sodium (Na, 47.6 mg kg −1 ), silver (Ag, 11.6 mg kg −1 ), magnesium (Mg, 8.9 mg kg −1 ), potassium (K, 8.1 mg kg −1 ), copper (Cu, 6.8 mg kg −1 ), and silicon (Si, 5.0 mg kg −1 ) (Table S15).…”