US2315957A

US2315957A - Color stabilization of light distillates

Info

Publication number: US2315957A
Application number: US352132A
Authority: US
Inventors: Amiot P Hewlett
Original assignee: Standard Oil Development Co
Current assignee: Standard Oil Development Co
Priority date: 1940-08-10
Filing date: 1940-08-10
Publication date: 1943-04-06
Anticipated expiration: 1960-04-06

Description

Patented Apr. 6, 1943 COLOR STABILIZATION OF LIGHT DISTILLATES Amiot P. Hewlett, Summit, N. J., assignor to Standard Oil Development Company, a corporation of Delaware,

No Drawing. Application August 10, 1940,

Serial No. 352,132

7 Claims.

This invention relates to stabilization of light petroleum .distillates, such as refined gasoline,

It is known to those skilled in the art that even highly refined light distillates which are substantially colorless or water white generally contain components that under the accelerating photo-chemical action of sunlight cause discoloration. The undesirable changes in the appearance of the product made by this discoloration while the product is being stored or marketed makes the product unattractive, of lower value, and unsalable. Although dyes may be used in some of the products, such as gasoline, to mask the defect of color instability, they do not really correct this defect permanently, because the hydrocarbon product inherently continues to undergo changes in color, with the result that the dyed product will change in appearance.

An object of this invention is to provide a method for stabilizing the color of refined petroleum products by an agent which functions very efiectively for this purpose when added in small inexpensive concentrations and which has no deleterious effects in the uses of the products.

A further object is to provide purified low boiling petroleum distillates of light color with high color stability and of such purity and proper composition to meet commercial requirements.

This invention is based on the discovery that certain dihydric alcohols having suitable miscibility with petroleum products, more particu-,

larly the alkanediols or alkylene glycols containing 4 or more carbon atoms, such as pentanediols, when present in the light colored petroleum products in very small concentrations, of less than 1% or of the order of 0.05% to 0.2% by weight, function very satisfactorily in decreasing the tendency of these products to lose color even when these products are subjected to highly intensified sunlight stability tests.

It was found that this type of stabilizing agent should be preferably a dihydroxy alcohol saturated with respect to carbon bonds and should have a sufficiently low melting point in order to be suitably soluble in the hydrocarbon distillate, for otherwise it has a tendency to be thrown out of solution and thereby make the product cloudy.

The more specific varieties of these alcohols which may be selected is a matter of economy andspecific use of the product in general, the dihydric alcohols having from 4 to 5 carbon atoms per molecule are considered the most useful under'ordinary conditions, but dihydric alcohols having up to '8 carbon atoms per molecule may also be employed.

The literature describes a number of methods by which compounds of this class can be prepared. One of the general methods involves halogenation of a suitable hydrocarbon followed by hydrolysis of the dihalide. There are a number of commercial processes which make available some of the preferred dihydric alcohols, as for example the pentanediols which are prepared by catalytic hydrogenation of furfuryl alcohol or acetyl acetone. While such commercial procedures tend to form isomeric mixtures of the dihydric alcohols, it is found that they make available the dihydric alcohols which are of particular interest, namely, those in which the hydroxyl group are attached to non-adjacent carbon atoms, i. e. the carbons of the hydroxyl group are in the beta gamma, or delta positions, as for example mixtures of pentanediols comprising principally pentanediol-1,5 and -2,4.

The following example is presented to illustrate the use of the dihydric alcohols as color stabilizers 'and to demonstrate their effectiveness:

Example A sample of refined gasoline having a +24 Saybolt color was used as a base stock. Pentanediols obtained as a by-product from the manu facture of tetrahydrofurfuryl alcohol was added to this base stock in a concentration of 0.1% by weight. Samples of this blend and of the base stock run as a blank were exposed to direct intensified light having the wave length characteristic of mid-day summer sunlight for periods of 15, 30, 60, and minutes in Pyrex glass bottles. The following data were obtained:

Color, Saybolt Sampln After exposure to the light for Origs 2.0 so 180 mm. mm. mm. min.

1. Gasoline base +24 +13 1 +3 +0 2. Gasoline base +01% pentanediols.. +23 +17 +13 +12 +9 It is to be observed that the color stabilizing action represented by that of the added dihydric alcohol is a ,very significant improvement, for it means that such compositions would not noticeably discolor to the naked eye when exposed to diflused sunlight in ordinary glass containers over very long periods of time.

The color stabilizing agents of this invention are of great value for stabilizing solvents and krrosene, which in general are desirably used in water white condition. In gasoline the stabilizing agents may be used together with dyes and other types of agents used to increase the antiknock value or to improve the fuel in other respects. They may be added to the hydrocarbon products derived from petroleum by straight distillation or by any of the known conversion I processes, and after these products are given the customary refining treatments with acids, bases, salts, clays and the like; also, they may be added prior to a final filtration treatment.

It is to be understood that this invention is subject to various modifications, as for example, the dihydric alcohols may contain a branched alkyl group or some substituent group such as an amino group, and is not to be limited by the specific example given for the purpose of illustration.

I claim:

1. The method of stabilizing the color of a refined substantially colorless light petroleum oil product which comprises dissolving in said product a small but sufficient proportion of pentane diol in the range from 0.05% to about 1% by weight to suppress discoloration of the product by the action of sunlight radiations.

2. The method as described in claim 1 in which radiations.

said pentanediol contains hydroxyl groups attached to non-adjacent carbon atoms.

3. A refined substantially colorless petroleum distillate oil blended homogeneously with a suificient proportion of pentanediol ranging from 0.05% to about 1% by weight'tor suppressing discoloration of the oil by the action of sunlight 4. A composition as described in claim 3 in which said pentanediol consists of the isomers pentanediol-1,5 and pentanediol-2,4.

5. A motor fuel blend comprising substantially colorless refined gasoline hydrocarbons blended with a suflicient proportion of pentanediol ranging from 0.05% to about 1% by weight or said hydrocarbons to suppress discoloration of the blend by the action of sunlight radiations.

6. A substantially colorless refined kerosene blended homogeneously with a sufficient proportion of pentanediol ranging from about 0.05% to about 1% by weight to suppress discoloration of the kerosene by the action of sunlight radiations.

'7. A color stable solvent comprising a refined naphtha solvent blended homogeneously with a suflicient proportion of pentanediol in the range from 0.05% to about 1% by weight to suppress discoloration oi the naphtha solvent by the action of sunlight radiations.

AMIOT P. HEWLET