| 摘要 |
A process for improving the colour and colour stability of a petroleum lubricating oil base stock comprises hydrofining the lubricating oil base stock in the presence of a hydrofining catalyst and hydrogen, treating the hydrofined oil with an aqueous alkali or alkaline earth metal hydroxide at a temperature within the range 400 DEG to 700 DEG F. and separating the thus treated oil from the metal hydroxide by distilling the oil in direct contact with solid metal hydroxide. |
