Abstract
Chemical changes and reactions in the aromatic components of Kuwait light lubricating oil distillate on hydrotreating were investigated. The original distillate was hydrotreated at 300∼390°C and under constant space velocity using Ni-Co-Mo catalyst. The original distillate and the hydrotreated oils were analysed by the use of low voltage mass spectrometric technique. The results were as follows;
(1) The main types of reactions involved in the lubricating oil hydrotreating are the hydrodesulfurization of the sulfur compounds, the partial hydrogenation of the polyaromatic hydrocarbons, the saturation of the monoaromatic hydrocarbons and the hydrocracking of the hydrocarbons. These reactions occur successively in this order.
(2) At the moderate temperature next two reactions occured mainly, the hydrogenolysis of the sulfur compounds and the formation of the monoaromatic hydrocarbons caused by the partial hydrogenation of the polyaromatic hydrocarbons. Under these conditions saturated components increased little. And the physical properties of the hydrotreated oil changed not so much, and were proportional to the degrees of hydrodesulfurization.
(3) At higher temperature considerable increase in the saturated components were observed according to the saturation of the monoaromatic hydrocarbons and to the hydrocracking of the hydrocarbons. The physical properties of the hydrotreated oils changed markedly under these conditions.
(4) The reactivities of the sulfur compounds in the lubricating oil distillate differed little by the types of compounds. It was considered from the changes of the diaromatic hydrocarbons in hydrotreating, that most of the trinuclear aromatic sulfur compounds in Kuwait light lubricating oil distillate were alkylnaphthothiophenes. And alkylthiophenes could not be found in this distillate.