Re-refinement of Used Motor Oil


Each year approximately 1.5 billion gallons of used motor oil is drained from the U.S. stock of petroleum lubricated engines in autos and other equipment. The industry has long recognized that used motor oils can be recycled by removing the contaminants which accumulate from use. Prior to World War II used motor oil was re-refined using a process involving the addition of sulphuric acid in order to separate the contaminants from the useful hydrocarbon components of used motor oil. Re-refining processes of the type involving the addition of sulphuric acid to used motor oil are no longer used because they result in the generation of large amounts of highly toxic acidic sludge which cannot be disposed of economically. Additionally, such re-refining techniques do not fulfill the requirements of ASTM Designation: D 6074-99. More recently, used motor oils have been re-refined utilizing a process known as hydrotreating. In accordance with the hydrotreating process, used motor oils are treated with hydrogen under high pressure. Hydrotreating is successful in removing olefins and alkanes from used motor oils and can also be used in removing heteroatoms therefrom. However, the hydrotreating process is expensive to the point that it cannot be operated profitably. Researchers at Miami University have developed a re-refining process that employs treatment with an organic or inorganic base in the presence of a phase transfer catalyst. This process is effective at removing polynuclear aromatic hydrocarbons, sulphur-containing substances, nitrogen-containing substances and other contaminants from used motor oil and related distillates. A particular advantage of this process is that it can safely, effectively, and economically meet newer ASTM Designation standards for physical, compositional, chemical and toxicological properties when many competitive re-refining technologies cannot.

PATENT STATUS: 7,662,274 and additional

INVENTOR: Richard Taylor

Susan McDowell, Ph.D.
Vice President for Research & Innovation
102 Roudebush Hall