Mineral oils: processes and products – Refining – Purifying used oil
Reexamination Certificate
2001-01-04
2001-11-20
Myers, Helane E. (Department: 1764)
Mineral oils: processes and products
Refining
Purifying used oil
C208S179000
Reexamination Certificate
active
06319394
ABSTRACT:
TECHNICAL FIELD
This invention relates generally to the removal of contaminants from used oil, and more particularly to a method of removing acidic compounds, color, and polynuclear aromatic hydrocarbons, and removing or converting heteroatoms from petroleum distillates, particularly used motor oil distillates.
BACKGROUND AND SUMMARY OF THE INVENTION
It has long been recognized that used motor oils can be recycled by removing the contaminants which accumulate therein during operation of the motor vehicles in which the motor oils are utilized. Recently, the American Society for Testing and Materials (ASTM) has promulgated its Designation: D 6074-99 wherein the ASTM Committee D-2 on Petroleum Products and Lubricants has promulgated standards for re-refined base oils. Included in Designation: D 6074-99 are numerous attributes of base oils, including attributes relating to physical properties, compositional properties, chemical properties, and toxicological properties.
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 at high temperature and pressure. Hydrotreating is successful in saturating olefins and aromatics in 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.
U.S. Pat. No. 5,814,207 discloses a used motor oil re-refining method and apparatus wherein up to four evaporators are connected one to another in a series. It will therefore be understood that the apparatus of the '207 patent is expensive to install and use. More importantly, the used motor oil re-refining method of the '207 patent cannot meet the requirements of ASTM Designation: D 6074-99 because it cannot remove heteroatoms and because it cannot meet the toxicological requirements of the designation.
Co-pending U.S. application Ser. No. 09/250,741 filed Feb. 16, 1999, and assigned to the assignee hereof discloses a re-refining process wherein used motor oil is treated with an organic or inorganic base in the presence of a phase transfer catalyst. The process is successful in removing acidic compounds and color and in removing or substituting heteroatoms from used motor oil distillates. Co-pending application Ser. No. 09/265,903 filed Mar. 24, 1999, and also assigned to the assignee hereof discloses a re-refining process wherein used motor oil is contacted with a highly polar organic solvent, such as N,N-dimethylformamide. The process is successful in removing polynuclear aromatic hydrocarbons, sulphur-containing substances, nitrogen-containing substances, and other contaminants from used motor oil and distillates.
The present invention comprises a process for re-refining used motor oils wherein the process of application Ser. No. 09/250,741 and the process of application Ser. No. 09/265,903 are operated in series. The process of the invention is unique in that it is the only known process which safely and economically fulfills all of the requirements of ASTM Designation: D 6074-
99. dr
BRIEF DESCRIPTION OF THE DRAWINGS
A more complete understanding of the invention may be had by reference to the following Detailed Description when taken in conjunction with the accompanying Drawings wherein:
FIG. 1A
is the first part of a diagrammatic illustration of a method of removing contaminants from petroleum distillates comprising the preferred embodiment of the invention;
FIG. 1B
is a continuation of
FIG. 1A
;
FIG. 2A
is the first part of a diagrammatic illustration of a method of removing contaminants from petroleum distillates comprising a variation of the preferred embodiment; and
FIG. 2B
is a continuation of FIG.
2
A.
REFERENCES:
patent: 6007701 (1999-12-01), Sherman et al.
Conn Garrett M.
Gorman William A.
Hershberger James W.
Hofacker Amanda L.
Sherman Jeffrey H.
Miami University
Myers Helane E.
O'Neil Michael A.
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