A Comparison of the Light Lubricating Oil Fractions from Three Different Crudes in Hydrotreating

Abstract

Three straight-run light lubricating oil fractions from Kuwait, Venezuela and California crudes were hydrotreated over NiCoMo-Al2O3 catalyst by the flow method for the purpose of studying the difference in reactivities of these three fractions and the relationship between the stabilities and the chemical composition of the oils. The reactivities of the fractions under hydrotreating were very different owing to their origins. Results were as follows;(1) Under the mild conditions decrease in viscosity was proportional to the degree of desulfurization, but under severe conditions (above 80∼90% desulfrization) rapid decrease in viscosity by the cracking etc. was observed. In case of naphthenic oils containing much oxygen-compounds, considerable viscosity decrease was observed in the initial hydrotreating stage. It was supposed that these viscosity decrease was due to the hydrocracking of the oxygen-compounds.(2) CA% in ring analysis decreased according to the hydrodesulfurization. In case of Kuwait oils CP% increased and CN% did not change, on the contrary CP% did not change and CN% increased in California oils. And in Venezuelan oils both CP and CN% gradually increased.(3) Oxidation stability of the hydrotreated oils had good relation with the total sulfur content of the oils. In the of 0.1∼0.4wt% total sulfur, a maximum oxidation stability was obtained. Hydrotreated Kuwait oils and Venezuelan oils had these Optimum sulfur California oils had inverse relationship, but after the undesirable nitrogen-compounds were eliminated, same Optimum sulfur range appeared in the same range.