Reduced vapor pressure gelled fuels and solvents

Abstract

The present invention relates generally to gelled fuels and solvents. Specifically the invention relates to gel thickeners that reduce vapor pressure in fuels and solvents and are shear thinning (pseudoplastic or thixotropic) or are shear thickening and remain pourable and flowable. Still more specifically, the invention relates to nonaqueous gels made with diblock copolymers that reduce the Reid Vapor Pressure of gelled gasoline and lower the total volatility of gelled hydrocarbon solvents. These gels may contain secondary amino acid or triblock polymer gelling agents. The invention includes gel compositions and methods of making gels.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates generally to gelled fuels and solvents in US class 44, subclass 272. Specifically the invention relates to gel thickeners that reduce vapor pressure in fuels and solvents and are shear thinning (pseudoplastic or thixotropic) or are shear thickening and remain pourable and flowable. Still more specifically, the invention relates to nonaqueous gels made with diblock copolymers that reduce the Reid Vapor Pressure of gelled gasoline and lower the total volatility of gelled hydrocarbon solvents. These gels may contain secondary amino acid or triblock polymer gelling agents. The invention includes gel compositions and methods of making gels.[0003]2. Background Information[0004]The vapor pressure of hydrocarbon fuels such as gasoline is controlled by both state and federal regulations. The purpose of these regulations is to reduce the production of environmental pollutants including ozone that cau...

AI Technical Summary

Benefits of technology

[0018]The present invention is a gelled fuel or solvent, for example gasoline, containing an effective amount of at least one diblock copolymer. The effective amount of copolymer may be determined on a case by case basis by those skilled in the art. It will be the type and amount of diblock copolymer that results in the gelled gasoline having a desired RVP and viscosity and also being pseudoplastic shear thinning so it can pass though fuel filters, pumps and injectors. In the case of gelled hydrocarbon solvents it may be sometimes desirable to add amino acid gelling agent or triblock, radial or star copolymers to the gel to lower the total amount of polymer required to produce an acceptable gel. The addition of these gelling agents and non diblock copolymers will cause the gel to become Newtonian or shear thickening, but not so much as the prior art and the gelled solvent will still be flowable. Flowable means that it can be poured easily and will flow through pipes.

[0019]The diblock copolymer should have a molecular weight between about 100,000 and about 500,000. The molecular weight of the diblock polymer, or diblock polymers, is a function of the desired viscosity of the gelled fuel or solvent, the resulting vapor pressure of the gelled fuel and its ability to be flowable or shear thinning for use with fuel injectors, pumps and filters so as to avoid the requirement of in line degraders.

[0022]The gelled hydrocarbon fuels and solvents taught by the present invention may also contain small amounts of amino acid gelling agents and triblock, radial or star copolymers in addition to the primary diblock copolymer. These low amounts of secondary gelling agents are useful in the range of about 0.1 to 5.0 weight percent to increase the viscosity of the gelled solvent while still allowing the gelled solvent to be pourable and flowable.

[0023]Yet a further benefit of the present invention is reduction in hydrocarbon product vapor pressure lowers the total amount of volatile organic compounds (VOC) that are released by the product into to the environment at a given temperature and pressure. One example of this benefit is that gelled fuel in an empty gas tank would have a lower vapor pressure, i.e. less VOC per unit volume of the gas tank, and thus would release less VOC pollution into the atmosphere during refueling, when the VOC vapor in the gas tank is forced out of the tank by the fuel flowing into the tank.

[0024]Yet another advantage of the pseudoplastic shear thinning gelled gasoline taught by the present invention is that the lower vapor pressure of the present invention lowers the risk of hydrocarbon-air explosion, while at the same time providing a gelled gasoline or solvent product that can flow through pumps, filters and small orifices, such as the jets in pores in fuel filters and fuel injectors in reciprocating gasoline or diesel engines, which may be stationary or may be in a car, truck or other mobile machinery. This advantage includes use of the present invention to provide a sprayable hydrocarbon containing gel with reduced vapor pressure to make fuel air explosion less likely while retaining the ability to flow properly through fuel spray nozzles in an aircraft reciprocating or turbojet engine or through the fuel injector plate orifices in an expendable or reusable rocket engine.

Problems solved by technology

These oxygenates are expensive and do not remove the need to control the gasoline's vapor pressure.

When the amount of butane in gasoline is reduced, the octane rating of the gasoline goes down, which makes engines knock and hard to start.

This requirement for the use of in-line degraders made the use of gelled fuels economically impractical.

Their elimination to lower RVP increases the price of the final gasoline product.

But the oxygen additives in reformulated gasolines have raised environmental concerns.

MTBE, for example, has leaked into drinking water in California, leading the state to phase out the use of this additive.

The NRC found that, compared with MTBE blends, ethanol blends result in more pollutants evaporating from vehicle gas tanks.

Low RVP gasoline has a lower vapor pressure and thus a lower evaporation rate and lower volatility than conventional gasoline, but it costs more to make.

Images