Detergent Motor Fuel Composition

Abstract

Detergent motor fuel composition containing a carbamate represented by the formula: in which R is a hydrocarbyl radical having from about 12 to 20 carbon atoms and R' is hydrogen or an alkyl radical having from one to two carbon atoms and x has a value from 2 to 4.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

Modern internal combustion engine design is undergoing important changes to meet stricter standards concerning engine and exhaust gas emissions. A major change in engine design recently adopted is the feeding of blow-by gases from the crankcase zone of the engine into the intake air supply of the carburetor rather than venting these gases to the atmosphere as in the past. The blow-by gases contain substantial amounts of deposit-forming substances and are known to form deposits in and around the throttle plate area of the carburetor. These deposits restrict the flow of air through the carburetor at idle and at low speeds so that an overrich fuel mixture results. This condition produces rough engine idling, stalling and also results in excessive hydrocarbon exhaust emissions to the atmosphere.

2. Description of the Prior Art

A gasoline which has carburetor detergency properties and in which one of the additive components is an N-alkyl-substituted alkylene diamine is disclosed in U.S. Pat. No. 3,031,278. U.S. Pat. No. 2,991,162 discloses carburetor detergents additives for gasoline obtained by reacting an N-alkyl propylene diamine with ethylene carbonate or propylene carbonate to produce a two-component detergent additive consisting of a carbamate and a urea compound.

SUMMARY OF THE INVENTION

A class of relatively high molecular weight substituted carbamates are provided as carburetor detergents when employed in a liquid hydrocarbonaceous fuel for an internal combustion engine. These carbamates are characterized by being essentially neutral compounds having no basic amino nitrogen yet, surprisingly, retaining their activity as carburetor detergents. This is an important improvement over some commercially available carburetor detergents having a basic amino nitrogen which reacts with acidic rust inhibitors resulting in a loss of their detergency properties.

The fuel composition of the invention mitigates or overcomes the problem of deposits lay-down in the carburetor of an internal combustion engine. When a gasoline of the invention is employed in an engine in which the carburetor has had a substantial build-up of deposits from prior operations, a severe test of the detergency property of the fuel, this gasoline is very effective for removing substantial amounts of the preformed deposits.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The substituted carbamate additive employed in this invention may be represented by the following formula:

in which R is a hydrocarbyl radical having from about 12 to about 20 carbon atoms, R' is hydrogen or an alkyl radical having from one to two carbon atoms and x has a value from 2 to 4. In a preferred embodiment, the hydrocarbyl radicals indicated by R are aliphatic hydrocarbyl radicals having from 16 to 18 carbon atoms and x has a value of 3.

The additive of the invention is prepared by reacting an amino-amide, with an alkylene carbonate under suitable conditions to produce the noted compound. The amino-amides which can be employed are represented by the formula:

in which R is a hydrocarbyl radical having from about 12 to 20 carbon atoms and x has a value from 2 to 4. The preferred amino-amides are those in which each R represents the same or different saturated or unsaturated aliphatic hydrocarbon radical having from 16 to 18 carbon atoms. Commercial amino-amides are available in which R represents a mixture of aliphatic radicals derived from naturally occurring materials. Specific amino-amides which can be employed include:

N-oleyl trimethylenediamine-oleamide (Duomeen O-Oleamide),

N-cocotrimethylenediamine-oleamide (Duomeen C-Oleamide),

N-stearyltrimethylenediamine-oleamide (Duomeen S-Oleamide),

N-tallow trimethylenediamine-oleamide (Duomeen T-Oleamide),

N-c.sub.10 - c.sub.14 sec. alkyltrimethylenediamine oleamide,

N-c.sub.14 - c.sub.15 sec. alkyltrimethylenediamine oleamide,

N-c.sub.10 - c.sub.14 sec. alkyltrimethylenediamine stearamide,

N-c.sub.14 - c.sub.15 sec. alkyltrimethylenediamine stearamide,

N-dodecyltrimethylenediamine stearamide,

N-dodecyltrimethylenediamine lauramide, and

N-laurylethylenediamine dodecanamide.

The alkylene carbonate component for preparing the additive of the invention is represented by the formula:

in which R' is hydrogen or an alkyl radical having from one to two carbon atoms. Particularly suitable compounds are ethylene carbonate and propylene carbonate.

The amino-amide and the alkylene carbonate are reacted using at least 1 mole of the alkylene carbonate per mole of the amino-amide in the reaction. The use of a substantial molar excess of the alkylene carbonate, which assures substantial neutralization of the amino-amide, i.e. at least 75 percent neutralized or more preferably at least 90 percent neutralized, is preferred and proportions of 1 to 2 moles of alkylene carbonate per mole of the amino-amide are generally employed. The reaction is conducted by mixing the components and effecting the reaction at a temperature ranging broadly from about 0.degree. to 165.degree. C. The preferred reaction temperature range is from 50.degree. to 150.degree. C. This reaction may be promoted by the use of a small amount of a catalyst, such as phosphoric acid.

Any gasoline suitable for a spark-ignited, internal combustion engine can be used in the practice of this invention. In general, the base fuel will consist of a mixture of hydrocarbons in the gasoline boiling range, that is boiling from about 80.degree. to about 450.degree. F. The hydrocarbon components of the base fuel can consist of paraffinic, naphthenic, aromatic and/or olefinic hydrocarbons obtained by thermal or catalytic cracking or reforming of petroleum hydrocarbons. This base fuel will generally have a Research Octane Number from about 85 to 102.

The carbamate of the invention can be advantageously employed in a motor fuel composition in a concentration ranging from about 0.0005 to 0.1 weight percent. The preferred concentration of the additive is an amount from about 0.001 to 0.1 weight percent.

The following example illustrates the method of preparing the carbamate additive.

EXAMPLE I

One mole of N-oleyltrimethylenediamine-oleamide was heated to 150.degree. C., 0.8 weight percent of concentrated phosphoric acid added and 2 moles of propylene carbonate gradually added and reacted over several hours. The reaction mixture was continuously stirred overnight while being kept at about 150.degree. C. Thereafter, the reaction mixture was cooled, diluted with benzene and water-washed several times to remove excess carbonate. The resultant solution was dried and stripped of solvent to recover the carbamate. The carbamate product had a TBN total base number, of about 10, a hydroxyl number of about 56 and was about 90 percent neutralized.

The additives of the invention are tested for their effectiveness as carburetor detergents for gasoline in the Chevrolet V-8 Carburetor Detergency Test. This test is run in a specially modified Chevrolet V-8 engine mounted on a test stand and equipped with a four barrel carburetor. The two secondary barrels of the carburetor are sealed and each of the primary barrels modified so that an additive fuel can be run in one barrel while a base fuel is run in the other. The primary carburetor barrels were previously modified so that they had removable aluminum inserts in the throttle plate area in order that deposits formed in this area could be conveniently weighed.

In a procedure designed to determine the effectiveness of an additive fuel for removing preformed deposits in the carburetor, the engine is run for a period of time usually 24 or 48 hours using the base fuel as the feed to both barrels while the engine blow-by products are circulated to the air inlet of the carburetor. The weight of the deposits on both sleeves is determined and recorded. The engine is then cycled for 24 additional hours with the base fuel being fed to one barrel, the additive fuel to the other barrel and no blow-by products to the carburetor air inlet. The inserts are then removed from the carburetor and weighed to determine the difference between the performance of the additive and non-additive fuels in removing the preformed deposits. After the aluminum inserts are cleaned, they are replaced in the carburetor and the entire process repeated with the fuels feeds to the carburetor barrels reversed in order to minimize differences in fuel distribution and barrel construction. The deposit weights in the two runs are averaged and the effectiveness of the base fuel and of the additive fuel for removing deposits expressed in percent.

The base fuel employed in the following examples was a premium grade gasoline having a Research Octane Number of about 101 and containing 3 cc. of tetraethyl lead per gallon. This gasoline consisted of about 25% aromatic hydrocarbons, 20% olefinic hydrocarbons and 55% paraffinic hydrocarbons and boiled in the range from about 90.degree. to 365.degree. F. In certain cases indicated in the examples a minor amount of a conventional rust inhibitor and/or upper cylinder lubricating oil was used. These have no significant effect on the detergency test results.

EXAMPLE II

Carburetor Detergency Test

Additive Run Detergency Additive Base Fuel Fuel .DELTA. __________________________________________________________________________ 1 7 PTB of N-hydroxy 32.sup.a 71 39 propyl carbamate of N- oleyl trimethylene- diamine oleamide 2 7.5 PTB of the linoleic 6 17 11 dimer acid salt of N- oleyltrimethylenediamine oleamide + 3.5 PTB of linoleic dimer acid 3 10 PTB propylene +.sup.b + 0 diamine-dioleamide 4 6 PTB of the acetylated 16.sup.a 20 4 N-oleyl trimethylene- diamine oleamide 5 5 PTB of the reaction 7 13 6 product of N-oleyl trimethylenediamine oleamide and formaldehyde (Schiff Base) 6 5 PTB of the reaction 17.sup.c 29 12 product of N-oleyl trimethylenediamine oleamide and formaldehyde 7 5 PTB of N-oleyl 24 66 42 trimethylenediamine oleamide __________________________________________________________________________ .sup.a The Base Fuel employed in this Run contained 0.5 vol. percent of a mineral oil having an SUS Viscosity at 100.degree. F. of about 100 and 72 PTB of a mineral oil solution containing about 30 weight percent of a rust inhibitor from oxidized mineral oil. .sup.b Indicates increase in deposits. .sup.c The Base Fuel contained 0.5 volume percent of a mineral oil blend consisting of about 84% of a mineral oil having an SUS Viscosity at 100.degree. F. of about 100, about 1% of a rust inhibitor and 15% of polypropene of about 850 average molecular weight.

The data show that the neutral carbamate of the invention, Run 1 retains a high level of carburetor detergency when employed in gasoline as compared to Runs 2 through 6 where this detergency property is lost. Run 7 exemplifies a commercial gasoline detergent having a basic amino nitrogen function.

Claims

We claim:

1. A motor fuel composition comprising a mixture of hydrocarbons in a gasoline boiling range and a minor detergent amount of a carbamate represented by the formula:

in which R is a hydrocarbyl radical having from about 12 to 20 carbon atoms and R' is hydrogen or an alkyl radical having from one to two carbon atoms and x has a value from 2 to 4.

2. A motor fuel composition according to claim 1 in which R is an aliphatic radical having from 16 to 18 carbon atoms.

3. A motor fuel composition according to claim 1 in which x has a value of 3.