Thesis (M.Sc.)--Chulalongkorn University, 1996

The quality improvement of used marine lubricating oil can be done by means of catalytic hydrogenation process. Which solved the undesirable problem obtaining from physical and chemical treatment and reduced the step of treatment. This research was to study the optimum condition in use of Nickel oxide/tungsten trioxide/aluminum trioxide, Nickel oxide/molybdenum trioxide/aluminum trioxide and Raney nickel catalyst. The changing of reaction time and concentration of catalyst was studied in order to find the condition which used least reaction tie and concentration of catalyst. Suitable condition of Nickel oxide/tungsten trioxide/aluminum trioxide catalyst was the reaction time of 2 minutes and the catalyst concentration of 30% and suitable condition of Nickel oxide/molybdenum trioxide/aluminum trioxide catalyst was the reaction time of 10 minutes and the catalyst concentration of 35% In use of these two types of catalyst, the hydrogenated oil obtained from this condition having desirable properties, especially in terms of viscosity index, color and sulfur content. While the suitable condition of Raney nickel was the reaction time of 10 minutes and the catalyst concentration of 35%. The hydrogenated oil obtained from this condition having desirable properties, especially in terms of viscosity index, color, sulfur content and flash point.