175Refining Processes for Used Oil Recycling to Base Oils or Fuels
7.5 DISTILLATION AND HYDROGENATION PROCESSES
Distillation of petroleum and its products followed by hydrogenation are common
renery options (Speight and Ozum 2002; Hsu and Robinson 2006; Gary et al. 2007;
Speight 2014). Thus, the replacement of the clay treatment of the distilled base oil
fractions by hydrogenation overcame the problem of disposal of the spent clay and
was a more environmentally acceptable process in many cases. The processes sug-
gested generally involve distillation of the used oil followed by processing in a guard
reactor to remove most of the heavy metals that would poison the catalyst in a con-
ventional hydrotreatment. The oils are then hydrogenated ov ...