Internal-combustion engines – Lubricators – Crankcase – pressure control
Patent
1988-11-07
1990-12-18
Cross, E. Rollins
Internal-combustion engines
Lubricators
Crankcase, pressure control
210282, 208182, 252 9, F01M 100
Patent
active
049778714
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to the removal of carcinogenic agents (such as polynuclear aromatic compounds) and heavy metals (such as lead and chromium) from used lubricating oils.
Polynuclear aromatic compounds, especially those containing three or more aromatic nuclei, are frequently present in relatively small quantities in used lubricating oil, especially from gasoline engines where the high temperatures during engine operation tend to promote the formation of polynuclear aromatics in the oil. This leads to polynuclear aromatic concentrations higher than 100 parts per million renders disposal of the used oil hazardous.
According to this invention, carcinogenic agents (such as polynuclear aromatic hydrocarbons) and heavy metals (such as lead and chromium) can be significantly removed from lubricating oil used to lubricate the engine of a motor vehicle by the use of a system comprising a sorbent positioned within the lubricating system and through which the lubricating oil circulates, which is capable of removing substantially all of the polynuclear aromatic hydrocarbons from the lubricating oil.
The system of this invention is used in the lubricating system of a motor vehicle and is particularly suitable for gasoline engines, but it can be used for diesel engines. It is only necessary to have the sorbent located at a position in the lubricating system through which the lubricating oil must be circulated after being used to lubricate the moving parts of the engine. In a preferred embodiment the sorbent is part of the filter system provided for filtering oil, or it may be separate therefrom. The sorbent can be conveniently located on the engine, block or near the sump, preferably downstream of the oil as it circulates through the engine, ie after it has been heated. The system of the present invention may be used in automotive engines, railroad, marine and truck engines which may be gasoline, diesel, heavy fuel or gas-fired.
This means that the polynuclear aromatic hydrocarbons are removed by the sorbent during the normal flow of the lubricating oil through the system and they may, therefore, be removed and readily disposed of simply by removal of the sorbent. The polynuclear aromatics to be removed generally contain 3 or more aromatic rings and the present invention is far simpler than the currently required disposal of large volumes of lubricating oil having a high polynuclear aromatic hydrocarbon content.
Suitable sorbents comprise attapulgus clay, silica gel, molecular sieves, dolomite clay, alumina or zeolite, although we prefer to use activated carbon. It may be necessary to provide a container to hold the sorbent, such as a circular mass of sorbent supported on wire gauze. Alternatively the filters could comprise the solid compound capable of combining with polynuclear aromatic hydrocarbons held in pockets of filter paper.
We prefer to use active carbon since it is selective to the removal of polynuclear aromatics containing more than 3 aromatic rings. It has the added advantage that the polynuclear aromatics are tightly bound to the carbon and cannot be leached out to provide free polynuclear aromatics after disposal. Furthermore the polynuclear aromatics contained will not be redissolved in the used engine oil as it circulates. We also prefer to use activated carbon since it will also remove heavy metals such as lead and chromium from the lubricating oil
Particular types of activated carbons are advantageous for removal of polynuclear aromatics. Although most activated carbons will remove polynuclear aromatics to some extent, we have found particular types are preferred for removal of 3 and 4 ring aromatics. Characteristics such as active surface area and pore structure were found to be less important than the materials from which the activated carbon had been made. Wood and peat based carbons were significantly more effective than carbons derived from coal or coconut, presumably due to the combination of surface active species and a pore structure allowing large polynuclear aromatics access to
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Brownawell Darrell W.
Norris Donald J.
Shaub Harold
Bawden Peter C.
Cross E. Rollins
Ditsler John W.
Exxon Chemical Patents Inc.
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