US2037563A - Mineral oil composition - Google Patents

Description

Patented Apr. 14, 1936 UNITED STATES PATENT OFFICE MINERAL OIL COMPOSITION No Drawing. Application June 7, 1933, Serial No. 674,695

1 Claim.

This invention relates to the production of lubricating oils with low pour points.

It is known that the pour point of a lubricating oil of ordinary composition is determined, in

5 part, by the content of waxy materials dissolved in the liquid hydrocarbons, and that at a critical low temperature these waxy materials separate in crystals which interfere with the fluid movement of the oil. It is also known that the pour point of an oil containing waxy material may be lowered by the addition of a small quantity of some material, dissolved in the oil, which modifies the normal crystallization of the waxy material.

The present invention resides in the discovery that a material suitable for use as a pour point depressant may be derived from adsorbent earth which has been utilized in the filtration of the unrefined residue of petroleum distillation com.

monly described as cylinder stock. The chemical composition of the material so derived is complex and varies with the character of the cylinder stock, and it has not yet been ascertained to which constituent or constituents the value as a pour-point depressant is to be attributed. However, it has been found sufiicient, for practical purposes, to use without separation the material or materials which can be derived from the adsorbent earth by means of a solvent such as ethanol, or a mixture of ethanol and chloroform, after the clay has been washed with a volatile petroleum solvent such as petroleum ether or naphtha.

A satisfactory method for the production of the material in question is as follows: adsorbent earth which has been used, in the ordinary manner, for the filtration of a high-viscosity steam-refined cylinder stock, is first washed with petroleum ether, until the washings are practically free from oil. The earth is then washed with a mixture of chloroform and ethanol until substantially all of the material removable by this mixture has been extracted. From this second solution the solvents are then removed by distillation,

leaving the tarry viscous material which is .desired. The. solution of a small percentage of this material in a Wax-containing refined lubricating oil of moderate viscosity will substantially lower the pour point of the oil. 5

As a specific example of the use of this pourpoint depressant, it was added to a refined petroleum lubricant stock having a Saybolt universal viscosity, at 210 F., of seconds. Before the addition of the depressant, the pour 10 point of the oil was 30 F. The addition of the depressant in an amount equal to 2% of the weight of the oil lowered the pour point to 0 F., while the addition of 5% lowered the pour point to -.15 F. v

The quantity of depressant required for definite results depends upon the character of the lubricant stock, particularly with regard to its viscosity and its wax content. An oil of high viscosity and low wax content may be afiected 20 little or not at all by the addition of a depressant, while an oil of low viscosity and high wax content will be most susceptible to the use of the depressant.

The pour-point depressant with which this in- 25 vention is concerned may be derived from the adsorbent earth and separated from undesirable material by the use of various combinations of solvents, and the mention of particular solvents in the specification and the claim is intended 30 merely to identify the material, but not to limit the invention to any particular method of deriving it from the adsorbent earth.

The invention claimed is:

The combination, with a refined petroleum lu- 35 bricant stock containing waxy material, of an' amount, suflicient to lower substantially the ,pour point of said stock, of that part, exclusively, of the material adsorbed from residual cylinder stock by adsorbent earth, which is removable 40 from said earth by washing with ethanol but not by washing with petroleum ether.

HARRY A. CURTIS.