Additive for hydrocarbon fuel consisting of non-acidic inorganic compounds of boron and related processes

Abstract

The present invention provides a fuel additive and a process for using and making the fuel additive. The fuel additive includes a non-acidic boron-containing salt in a carrier fluid. The fuel additive enhances combustion by increasing fuel efficiency or decreased pollutant output in an exhaust gas resulting from combustion of the fuel with the fuel additive.

Description

RELATED APPLICATIONS

This application is related to and claims priority and benefit of U.S. Provisional Patent Application Ser. No. 60/673,907, filed Apr. 22, 2005, titled “Additive For Hydrocarbon Fuel Consisting of Non-Acidic Inorganic Compounds of Boron and Related Processes,” which is incorporated herein by reference in its entirety.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to the field of fuel additives, and in particular, to a boron-containing additive for hydrocarbon fuels used to enhance efficiency and/or reduce pollution.

BACKGROUND OF THE INVENTION

Many hydrocarbon fuels have been used, each with its own advantages and drawbacks. Examples of such fuels include gasoline, natural gas, diesel, kerosene, jet fuel, LPG, heavy distillates, bunker fuel, ethanol, coal, other solid hydrocarbon fuels and the like. Chemical compounds have been used as fuel additives over the past century to improve various parameters, such as octane number, of various fuels. The use, and subsequent banning, of lead in gasoline has been known for a long time. Tetraethyl lead showed a positive effect on octane and a profoundly negative effect on the environment.

In addition to tetraethyl lead, several elements are known to have combustion catalyst characteristics in gasoline or other hydrocarbon fuels. Examples, in addition to lead, are manganese, iron, copper, cerium, calcium and barium. Each of these elements has advantages and disadvantages in particular applications. Drawbacks of certain iron compounds include limited solubility in gasoline, toxicity, and expense as an additive. Interaction with sulfur and creation of sulfide precipitate may also occur, which is undesirable.

Another commonly-used additive in gasoline is MTBE. While this compound boosts octane levels significantly, the compound is thought to be carcinogenic. Also, it mixes easily with water which is hazardous should there be a leak. Gasoline containing MTBE leaking from an underground tank at a gas station could potentially leach into groundwater and contaminate wells. As a result of the believed negative potential effect of MTBE on the environment, ethanol is also being evaluated as a gasoline additive to boost octane.

In addition to the industry goal of improved combustion efficiency, reduction of smoke and particulate emissions is also a concern, particularly for diesel fuel applications. The industry has not made substantial progress on development of a fuel additive for reducing smoke and particulate emissions.

Finally, adjustment of combustion parameters is made to attempt to maximize function to reduce CO and NOx. In spite of these and combinations of these attempts to minimize pollutants, fuel combustion continues to be a focus of interest to improve fuel efficiency and reduce pollutants.

A fuel additive that includes a combustion catalyst to reduce smoke and particulate emissions from bus, truck and automobile engines operating on gasoline fuels would be advantageous. Also advantageous would be a fuel additive that increases efficiency and/or decreases pollutants for diesel fuel applications. It would be advantageous to reduce smoke, particulate and nitrogen emissions from fuel applications. An additive that does not result in the formation of precipitates would be also advantageous. An additive for hydrocarbon fuel that reduces level of NOx produced would also be advantageous. Finally, an additive that remains stable during the combustion process would be advantageous.

SUMMARY OF THE INVENTION

Accordingly, the present invention provides a fuel additive comprising a mixture of at least one salt and a carrier fluid, the salt comprising [Y]_aB_bO_c, wherein [Y] is a cation and the salt is non-acidic, the carrier fluid being operable to maintain the salts within the carrier fluid in at least a partially dispersed state, the fuel additive being operable to enhance combustion when placed into contact with fuel in a combustion zone and combusted, the enhanced combustion being measurable by increased fuel efficiency or decreased pollutant output in an exhaust gas resulting from the combustion of the fuel and the fuel additive. A feature of the present invention is that [Y] is an ammonium compound. Alternately, [Y] is an alkali metal.

The present invention also advantageously provides a process for enhancing fuel performance of a hydrocarbon fuel in a combustion system having a combustion zone comprising the steps of providing a fuel additive comprising a mixture of at least one salt and a carrier fluid, the salt comprising [Y]_aB_bO_c, wherein [Y] is a cation and the salt is non-acidic, in an amount effective to enhance fuel performance to the combustion zone and combusting the hydrocarbon fuel with the fuel additive. A feature of the present invention is that the fuel can be a solid or liquid hydrocarbon fuel.

DETAILED DESCRIPTION

The present invention includes a fuel additive and a method of using the additive in relation to hydrocarbon fuel. The fuel additive of the invention includes a boron-containing salt which preferably includes [Y]₂B₄0₇, wherein Y is a cation. Ammonium is a preferred inorganic cation. Alkali metals are another preferred inorganic cation, more preferably those alkali metals with atomic weights under 50.0.

In one embodiment, the boron salts are at least partially dispersed in water or another aqueous fluid to create a boron-containing parent dispersion. The boron salts are dispersed in the water or aqueous fluid, and no dissociation or dissolving of the salts occurs. The stable dispersion of boron salts at a preferred particle size of 5 microns or less, more preferably from 2-5 microns, provides a heterogeneous combustion catalyst in hydrocarbon fuel that provides emissions reductions and fuel economy improvements.

In an embodiment of the present invention, the boron-containing parent dispersion is added or mixed with a dispersion fluid. The dispersion fluid is a fluid that is operable to maintain the salts within the dispersion fluid in at least a partially dispersed state and that is miscible, or capable of being maintained in solution, in the hydrocarbon fuel. In a preferred embodiment, the water, for example, is largely removed from the boron-containing parent dispersion in the dispersion fluid through thermal means to create the fuel additive. The dispersion fluid is preferably a Group II base oil. Other preferred dispersion fluids include light hydrocarbons, gasoline, polygas, kerosene, diesel, naphtha light oils, Group I, III, IV, V or VI base oils as defined by API, aromatic oils, polybutenes, polyglycols, heavier oils or combinations of the same.

The fuel additive is operable to enhance combustion when placed into contact with fuel, regadless of the fuel's sulfur content. Enhanced combustion means that fuel efficiency is increased when compared to fuel without the fuel additive, or that pollutant output in an exhaust gas from the combustion is decreased, or a combination of these effects. Typical pollutants can include NOx, particulate matter, carbon monoxide and other recognized pollutants resulting from the combustion of hydrocarbon fuel. It is noted that different geographical regions focus on minimizing a particular pollutant depending on air characteristics. Reduction of a target pollutant or a combination of pollutants, such as NOx and CO, is highly advantageous. Alternately, increased fuel efficiency results in a total lower volume of pollutants, as well as economic advantage.

When the fuel additive is prepared using ammonium compounds, ammonium compounds are defined as those compounds containing NR_x groups, where R can be for example, hydrogen. NH₄ is particularly preferred. Ammonium compounds have been found to have particularly strong catalytic combustion properties, for example, in terms of NOx reduction, when used in boron-containing salts in accordance with the present invention.

The borate salts are essentially neutral but more particularly are not highly acidic. In a preferred embodiment, the boron-containing parent dispersion has a pH between about 6.0 and 8.0. Boric acid is typically not present at this relatively neutral pH range. Pentaborates and tetraborates are disclosed herein, for example. The borate salts can be in any form including metaborate, orthoborate or any form of borate that is not acidic, or combinations thereof. The salts can be either anhydrous or in various levels of hydration. The preferred boron salts according to the present invention are inorganic, nonacidic, insoluble and dispersible.

The boron-containing parent dispersion of one embodiment of the invention can be used in any type of environment, for example, either hydrophilic or hydrophobic environments. In the case of a hydrophobic environment, it may be necessary that a carrier fluid or fluids be selected to allow for proper dispersion. In a preferred embodiment, the carrier fluid can be polyoxpropylene monols, diols and polyols, polyoxybutylene monols, diols and polyols, particularly Bayer Actaclear ND17. A dispersant used in conjunction with the carrier fluids to create the fuel additive is also encompassed in a preferred embodiment. Preferred dispersants include polyalkenyl succinimides such as Texaco TFA 4690C, Oronite ODA 78012 and Ethyl Hitec 646. For liquid hydrocarbon fuel applications, at least one carrier fluid can preferably be a fluid with at least some hydrophilic character that is miscible with the fuel to act as compatibilizing agent in conjunction with dispersant.

The fuel additive of the invention is useful to enhance combustion such that more complete combustion is achieved with increased combustion to CO₂ and H₂O as compared to the combustion of the fuel without the fuel additive. The outcome is the reduction of products of partial combustion as well as NO_x, thereby increasing fuel efficiency.

The fuel additive is used by adding the additive to the fuel in an amount sufficient to increase fuel efficiency and/or to reduce pollutants. The terms enhanced and enhanced combustion refer to either of these effects. An example of reduced pollutants is a reduction of NOx and CO in an exhaust gas produced from an internal combustion engine or direct fired open flame burner. Advantageously, both of these effects are observed though the addition of the fuel additive of the current invention. A preferred embodiment includes the addition of between about 5 and 10 ppm boron by weight into the fuel though the addition of the fuel additive. Increased amounts of boron up to 25 ppm boron by weight are effective as well. It is notable that a very cost-effective solution can be prepared with low weight percent of boron, i.e., less than 20 ppm. Another preferred target is less than 15 ppm boron. Relatively low concentrations of boron advantageously provide economic benefits, may be more environmentally acceptable and may provide cleaner operations in the engine with reduced deposits and residues.

Included in the invention is a process for enhancing fuel performance of a hydrocarbon fuel in a combustion system including the steps of providing the fuel additive described above in an amount effective to enhance fuel performance to the hydrocarbon fuel and combusting the hydrocarbon fuel with the fuel additive. The combustion system can be any means known to those with ordinary skill in the art for combusting hydrocarbon. The combustion system can include any of various internal combustion engines. In a preferred embodiment, this process is used with a liquid or liquefied hydrocarbon fuel. Alternatively, the process may also be utilized with solid hydrocarbon fuel. The result of adding the additive to the hydrocarbon fuel is an enhanced fuel that has a substantial amount of hydrocarbon fuel suitable for combustion, and an amount of the fuel additive operable to enhance combustion. Preferably, the enhanced fuel contains boron in an amount operable to reduce emissions and improve efficiency upon combustion of the enhanced fuel as compared to the combustion of the hydrocarbon fuel without the fuel additive. More preferably, the enhanced fuel contains boron of between about 5 and 10 ppm by weight. Increased amounts of boron up to 25 ppm boron by weight are effective as well. It is notable that a very cost-effective solution can be prepared with low weight percent of boron, i.e., less than 20 ppm. Another preferred target is less than 15 ppm boron.

An alternate embodiment of the invention includes a process for enhancing fuel performance of a hydrocarbon fuel in a combustion system including the steps of adding a chemical addition composition to the hydrocarbon fuel in an amount effective to enhance fuel performance.

The chemical addition composition, also called the dispersion fluid, can be created by creating an intermediate aqueous parent dispersion by dispersing the borate salt in water. The next step includes combining the aqueous boron-containing parent dispersion with a carrier fluid in the presence of various dispersants, surfactants and the like and then removing the water to create the boron-containing dispersion fluid.

The parent solution, or the boron-containing dispersion fluid of the invention, can be added into or include a combustion fuel. Again, it can be advantageous to include dispersants to promote dispersion in fuels that are hydrocarbon based. Exemplary fuels are kerosene, diesel fuel and residual fuels.

An enhanced fuel is created when a substantial amount of a fuel suitable for combustion is combined with an amount of the boron-containing parent dispersion or the chemical addition composition sufficient to reduce emissions or to increase efficiency upon combustion of the enhanced fuel. Diesel and gasoline are two examples of fuels suitable for combustion. Other hydrocarbon fuels useful for combustion in a combustion engine are also encompassed. In certain circumstances, the dispersion fluid is a quantity of a target fluid, that is, a fluid that contains the desired fuel.

EXAMPLE 1

Preparation of Boron-Containing Aqueous Parent Solution

Charged 83.5 grams of ammonium pentaborate octahydrate (NH₄B₅O₈−8H₂0; mol wt 544.3 grams/mole)) was added to 417.7 grams of deionized water. The mixture was heated with stirring to 80° C. until all of the salt had dispersed. The solution remained clear at 80° C. and contained 1.8% weight boron.

EXAMPLE 2

Preparation of the Boron-Containing Dispersion Fluid

To 1200 grams of a mineral oil basestock, in a 4-liter Erlenmeyer flask, was added 90 grams of Lubrizol 400A, a proprietary additive package containing a mixture of dispersants, and 180 grams of kerosene. The mixture was stirred at ambient temperature until clear solution was obtained. To the oil solution was added 166.0 grams of the boron-containing aqueous parent dispersion prepared in Example 1. The two solutions were mixed together using a high speed hand mixture to form a water-in-oil emulsion. The emulsion was transferred to a 3-liter round bottom flask equipped with agitator and Dean-Starke trap with condenser. The mixture was heated with agitation to a maximum temperature of 150° C. over a period of about one hour to remove the water. The result was a dispersion of the borate salt in the oil matrix. The final water content was 6,480 ppm with a final theoretical boron content of 1,827 ppm.

EXAMPLE 3

Preparation of Boron-Containing Two Cycle Engine Fuel Treatment

A lubricating oil suitable for dilution with gasoline and use as two cycle engine fuel was prepared by mixing the boron containing dispersion fluid of Example 2 with Tufflo 6036, a proprietary additive package containing various detergents and dispersants to a final boron content of about 300 ppm. Fuel was then added to the mixture at a 50:1 ratio to provide a final boron content of about 6 ppm.

EXAMPLE 4

Homelite Yard Broom II Leaf Blower Test

The Homelite Yard Broom II Leaf Blower is a hand held blower that uses a 30 cc two cycle gasoline engine. The leaf blower is used to screen for engine efficiency improvements, especially increased fuel economy. To establish a baseline, the standard Homelite two cycle oil was mixed 50:1 with regular unleaded gasoline of 87 octane. Exactly 250 milliliters of the fuel mixture was added to the leaf blower fuel tank. The engine was then run at full RPM until the fuel was totally consumed and the engine died. The run time, RPM and exhaust temperature were measured and recorded. The test was repeated using the boron-containing oil from Example 3 at 50:1 dilution and about 6 ppm boron. The result was an increase in RPM of 2.3%, a decrease in exhaust air temperature of 6.5% and an increase in run time of 11.8%. These values demonstrate a significant improvement in engine operation efficiency with the boron-containing oil of the invention.

EXAMPLE 5

Diesel Fuel Combustion in an Open Flame

A diesel fuel fired open flame burner was used to measure CO emissions. A baseline was established by burning untreated diesel at specific and controlled fuel and air mixtures. For this test the fuel:air mixture was not varied. The boron dispersion fluid of Example 2 was diluted to 20 ppm B with high sulfur No. 2 diesel. This mixture was then used to fuel the burner and over 14 measurements a reduction in CO of 11.5% was measured.

Claims

1. A fuel additive comprising a mixture of at least one salt and a carrier fluid, the salt comprising [Y]aBbOc, wherein [Y] is a cation and the salt is non-acidic, the carrier fluid being operable to maintain the salt within the carrier fluid in at least a partially dispersed state, the fuel additive being operable to enhance combustion when placed into contact with fuel in a combustion zone and combusted, the enhanced combustion being measurable by increased fuel efficiency or decreased pollutant output in an exhaust gas resulting from the combustion of the fuel and the fuel additive.

2. The fuel additive of claim 1 wherein the salt is selected from the group consisting of metaborate, pentaborate, tetraborate and orthoborate and combinations thereof.

3. The fuel additive of claim 1 further comprising [NH4]2B4O7.

4. The fuel additive of claim 1 further comprising an ammonium compound.

5. The fuel additive of claim 1 wherein the pH of the solution is between about 6.0 and 8.0.

6. The fuel additive of claim 1 wherein the salt is inorganic.

7. A process for enhancing fuel performance of a hydrocarbon fuel in a combustion system having a combustion zone comprising the steps of providing the fuel additive of claim 1 in an amount effective to enhance fuel performance to the combustion zone and combusting the hydrocarbon fuel with the fuel additive.

8. The process of enhancing fuel performance of claim 7 wherein the hydrocarbon fuel is a liquid hydrocarbon fuel.

9. The process of enhancing fuel performance of claim 7 wherein the hydrocarbon fuel is a solid hydrocarbon fuel.

10. The process of enhancing fuel performance of claim 7 wherein the combustion zone is within an engine operating on gasoline fuel.

11. The process of enhancing fuel performance of claim 7 wherein the combustion zone is within an engine operating on diesel fuel.

12. The process of enhancing fuel performance of claim 7, wherein the fuel additive is operable to enhance combustion when placed into contact with fuel in a direct fired burner or open flame in the combustion zone and combusted, the enhanced combustion being measurable by increased fuel efficiency or decreased pollutant output in an exhaust gas resulting from the combustion of the fuel and the fuel additive.

13. An enhanced fuel comprising a substantial amount of hydrocarbon fuel suitable for combustion, and an amount of fuel additive of claim 1 operable to enhance combustion.

14. The enhanced fuel of claim 13 wherein boron is present in the hydrocarbon fuel in an amount of between about 5 and 10 ppm by weight.

15. The enhanced fuel of claim 13 wherein the amount of fuel additive is the amount operable to reduce emissions upon combustion of the enhanced fuel as compared to the combustion of the hydrocarbon fuel without the fuel additive.

16. The enhanced fuel of claim 13 wherein boron is present in the hydrocarbon fuel in an amount less than about 25 ppm by weight.

17. A process for creating an enhanced hydrocarbon fuel for use in a combustion system comprising the step of:

adding an amount effective to enhance fuel performance to the hydrocarbon fuel of a chemical addition composition, the chemical addition composition comprising the product from the dispersion of a non-acidic borate salt in water.

18. The process of claim 17, wherein the salt is inorganic.

19. A process for creating a fuel additive for enhancing combustion of a hydrocarbon fuel, the process comprising the steps of:

adding the salt [Y]aBbOc, wherein [Y] is a cation and the salt is non-acidic, to a fluid to at least partially disperse the salt in the fluid to create a boron-containing parent dispersion;

mixing the boron-containing parent dispersion with carrier fluid such that the boron-containing parent dispersion is generally dispersed in the carrier fluid; and

removing a substantial portion of the fluid from the mixture of the boron-containing parent dispersion with the carrier fluid to create a fuel additive that is operable to enhance combustion when added to a combustion zone in the presence of a hydrocarbon fuel and combusted.

20. The process of claim 19, wherein the salt is inorganic.