US2256627A - Motor fuel - Google Patents

Description

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Patented Sept. 23, 1941 MOTOR FUEL Raphael Rosen, Elizabeth, N. J., assignor to Standard Oil Development Company, a corporation of Delaware No Drawing. Application October 31, 1939,

Serial No. 302,135

4 Claims.

This invention relates to motor fuels and their preparation. It relates, more particularly, to blends of motor fuels with unsaturated ethers which reduce knocking of high-compression, spark-ignition engines fueled by these blends. f Ethyl ether added to motor fuels as a priming a ent in the past was found to be a knock-inbut more recently, branched ethers, notably isopropyl ether, were found valuable as blending agents for reducing the knocking tendencies of gasoline motor fuels in modern highcompression engines.

By the present invention, another specific type of ethers is added to the class of substancesknown as high-octane fuel blending agents, and this makes available additional sources of fuel ingredients which compare favorably with isooctane and branched ethers in blending value.

In accordance with the present invention, it has now been found that unsaturated aliphatic ethers have a marked ability to improve the octane rating of motor fuels, comprising gasoline hydrocarbons obtained from petroleum by known commercial methods, particularly when double bonds between carbon atoms in the ether molecules are as close as possible to oxygen in the ether linkage. The presence and location of double bonds and branched radicals in ethers are now determined to be capable of influencing the, antiknock value of these compounds, in some respects, more than the presence of branched aliphatic hydrocarbon radicals in saturated ethers.

Motor fuel compositions were prepared by blending standardized gasoline reference fuels with unsaturated ethers in various volumetric concentrations, such as 5%, 20%, 30%,.

50%, and higher, and these compositions were in conjunction with a lead alkyl anti-knock agent. For example, dimethallyl ether:

in a by volume blend with the standardized gasoline reference fuel having a 65 octane numof 8.3 without the added lead alkyl anti-knock tested by the A. S. T, M. method for measuring their knock rating.

As a particular example, a 65 octane number reference fuel was blended with divinyl ether (CH2=CHOGH=CH2) to form a composition containing the ether in a concentration of 5% by volume. This composition, by the A. S. T. M. knock rating test, proved to have an octane number of 69.8, which represents a 4.8 octane number increase; consequently, the A. S. T. M. blending value of the vinyl ether amounts to 160.

Unsaturated aliphatic ethers having double bonds further removed from the ether group are represented by allyl ethers. The allyl ethers were found to have somewhat lower octane blending values than divinyl ether. However, a branched allyl ether blend showed especially good octane improvement at lower temperatures and agent, and 14.5 with added tetraethyl. lead.

The increase in octane number is a measure of reduced knocking experienced in the operation of the engine supplied with the fuel, and this number varies with the proportion of the blending agent used in the fuel.

Other unsaturated ethers analogous to divinyl ether and dimethallyl ether may be used. In general, these ethers have the constitutional formula:

wherein R and R represent hydrocarbon radicals, either alike or unlike, at least one of these groups being an aliphatic radical containing doubly linked carbon atoms. In more specific instances, one of the members R or R may contain a substituent such as an amino or a hydroxyl group in the hydrocarbon radical. As in a comparison of divinyl ether with dimethallyl ether, the double bond is preferably near the oxygen constituent, except when the fuel contains an alkyl lead antiknock agent or when the fuel is judged by engine performance at low temperatures.

Further representative=examples of these unsaturated ethers useful as anti-knock blending agents are the following: vinyl ether of ethylene glycol, vinyl phenyl ether, vinyl methallyl ether, vinyl propyl ether, vinyl isopropyl ether, isopropenyl phenyl ether, methallyl cyclohexyl ether, methallyl meta-cresyl ether, amino isopropyl ether, and amino-amyl vinyl ether.

The described unsaturated ethers may be looked upon as being either derivatives ,of unsaturated alcohols. Such unsaturated ethers may be synthesized individually or in mixtures by known condensation reactions of halogenated olefins with alcohols or hydroxy aromatic-compounds,

one or both of the reactants being branched aliphatic compounds. Also, unsaturated ethers of the desired types have been produced by the action of potassium hydroxide on halogenated others, by the action of acetylene on hydroxy organic compounds in the presence of catalysts, by decomposition of acetals, and other methods described in the literature.

The described unsaturated ethers may be blended in practically any proportion with gasoline hydrocarbons or motor fuels adapted for high compression engines of the Otto cycle type.

They may be used with various proportions of other anti-knock blending agents, such as alcohols, isopropyl ether, and aromatic amines.

In the practice of this invention, a selected unsaturated ether, or several of such ethers having boiling points within or close to the boiling range desired for thefuel composition are blended with a hydrocarbon fuel base in proportions usually ranging from about 5% to 50% by volume of the blend. In general, the fuel base comprises gasoline hydrocarbons and has a boiling range of about 100 F. or 200 F. to 400 F. or about 550 F. It is, therefore, best to blend the fuel base with the unsaturated ethers having boiling points below the end point limits of' 400 F. or 550 F. In preparing a high flash point safety fuel or a fuel for injection type engines, the fuel should have the higher initial and end points. The hydrocarbon fuel base may be obtained from mineral oils or gaseous hydrocarbons derived from any source and by any of the known commercial methods of manufacture, such as by catalytic cracking, thermal cracking, destructive hydrogenation, polymerization, alkylation, or hydrogenation.

Together with the described addition agents, other materials may be added to the fuel. Antioxidants which act as preservatives for the others may be added in small amounts, such as about 0.01% to 0.05%. Compounds which act in this capacity are aromatic, hydroxy, and amino compounds, e. g. alpha-naphthol, alpha-naphthylamine, phenyl alpha-naphthylamine, and hydroquinone. Other improving additives, such as lubricants, gum fluxes, corrosion inhibitors, dyes, etc., may also be used.

It is not intended that this invention be limited to the specific examples given for the p p se of illustration.- Any modification or variation which conforms to the spirit of the invention is intended to be included within the scope of the claims.

I claim: I

1. A motor fuel comprising a major proportion of gasoline hydrocarbons and an unsaturated ether selected from the group consisting of divinyl ether and dimethallyl ether blended with said hydrocarbons in a minor but effective octane improving amount.

2. A motor fuel comprising a mixture of gasoline hydrocarbons blended with about 5% to 50% by volume of divinyl ether.

3. A motor fuel comprising gasoline hydrocarbons blended with 5% to'50% by volume of dimethallyl ether.

4. A motor fuel comprising 5% to 50% byvolume of dimethallyl ether and a small amount of