Influence of Biodiesel on Base Oil Oxidation as Measured by FTICR Mass Spectrometry

Internal combustion engine lubricants are subject to thermo-oxidative degradation during use and must be designed withstand oxidation in order extend their useful life. Understanding the complex chemical process of is essential designing higher performing lubricants. In this study base oil samples composed a Group II oil, doped with three different levels biodiesel (B0, B15, B100), were subjected benchtop testing up 168 h, which mimics conditions experienced an internal engine. The resulting analyzed by Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS) for ultrahigh-resolution characterization monitor as function time biofuel content. Both negative-ion nanoelectrospray ionization positive-ion atmospheric pressure photoionization utilized. Most products found polyoxygenated species containing 1–8 oxygen atoms, number detected increasing time. Assessment maximum carbon protonated classes indicated involvement oligomerization reactions; additionally, modeling mean double bond equivalents (DBE) each class suggests carbonyl content particular oxidations B15 B100 compared that B0. correspond closely B0 samples, similar detected. showed significant increase generated at 24–72 h relative B15; however, observed all indicating level final point. FTICR MS shown afford new insights into