APPLICATION OF C-13 AND H-1 NUCLEAR-MAGNETIC-RESONANCE FOR THE EVALUATION OF CETANE RATING OF MIDDLE DISTILLATES

Proton and 13C nuclear magnetic resonance studies have shown that no direct relationship exists between cetane rating and contributions of the various structural groups to cetane index. Therefore, this empirical method can be recommended for research purposes only, and only in those cases where the sample is derived from the same streams on which the calculation was based. Since nuclear magnetic resonance cannot reveal the presence of cetane improvers in unknown samples, a new method for determining cetane number improvers, using negative-ion, chemical-ionization mass spectrometry, has been introduced for checking for the presence of such materials in comparative evaluation of cetane engine test and NMR data. © 1990.