Phosphite Antioxidants for Fuels and Related Methods

CROSS-REFERENCE TO RELATED APPLICATIONS

This PCT patent application claims priority to U.S. provisional patent application 63/275,746 having a filing date of November 4, 2021. The subject matter of U.S. provisional patent application 63275746 is incorporated by reference into this application in its entirety.

BACKGROUND OF THE INVENTION

It is well known that carbon-based fuels such as petroleum-based diesel, biodiesel, gasoline, and aviation fuel degrade over time at ambient and higher temperatures. This can lead to increased engine deposits, negative effects on fuel systems, and increased emissions. Water is a potential source of fuel corrosion. Because of this, a need remains to inhibit fuel degradation and to remove water from liquid fuels.

Combustion engines use these carbon-based fuels, and in doing so, yield unwanted combustionengine emissions such as: i) nitric oxide, ii) nitrogen dioxide, iii) carbon monoxide, and iv) residual hydrocarbons and particulates. These remains a need to reduce these unwanted combustion-engine emissions.

BRIEF SUMMARY OF THE INVENTION

A composition having a fluid mixture having a liquid fuel component and an antioxidant component; the liquid fuel component being petroleum-based diesel, biodiesel, gasoline, or aviation fuel; and the antioxidant component being a phosphite compound.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING Figure 1 shows two reaction mechanisms; the first reaction mechanism is a peroxide-scavenging reaction mechanism, and the second reaction mechanism is a water-scavenging reaction mechanism.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments are directed to a fluid mixture having: i) a liquid fuel component that is petroleum-based diesel, biodiesel, gasoline, or aviation fuel; and ii) a phosphite antioxidant component.

Petroleum-based diesel, biodiesel, gasoline, and aviation fuels are known.

Phosphite compounds are also known, and any known phosphite compound can be employed as an antioxidant in the above identified fuels. Useful phosphites include alkyl phosphites and aryl phosphites having the structure:

R ₂ o R _r O-P-O-R ₃ wherein each R is an independently selected moiety that is an alkyl, aryl, alkyl-aryl, or hindered aryl moiety. In embodiments, a hindered aryl moiety is an aryl moiety having attached thereto a branched-carbon-chain moiety that has three or more carbon atoms; nonlimiting examples of a hindered aryl moiety include: 1) an aryl moiety having attached thereto a tert butyl moiety, and 2) an aryl moiety having attached thereto a cumyl moiety.

In embodiments, phosphites having the following chemical structure are useful: wherein each R ¹ , R ² , R ³ , R ⁴ and R ⁵ is independently selected and is a Cio-Cis alkyl moiety; n is an integer ranging from 3 to 11; and the sum of Xi + X2 is an integer ranging from 1-500.

In some phosphorus-containing copolymer compound embodiments, such as those having the immediately above chemical structure, the compound has a weight ranging from 1000 to 30000 Daltons. In some other phosphorus-containing copolymer compound embodiments, such as those having the immediately above chemical structure, the compound has a weight ranging from 400 to 30000 Daltons. In some other phosphorus-containing copolymer compound embodiments, such as those having the immediately above chemical structure, the compound has a weight ranging from 500 to 30000 Daltons.

A chemical compound having the structure: wherein each R ¹ , R ² , R ³ , R ⁴ and R ⁵ is independently selected and is a Cio-Cis alkyl moiety; n is an integer ranging from 3 to 11; and the sum of X1 + X2 is an integer ranging from 1-1000, can be obtained commercially. Or, it can be manufactured using a known method. In embodiments, phosphite compounds having the following chemical structure are also useful: wherein each R is an independently selected alkylphenol-free moiety that is a C1-22 alkyl, C6-40 cycloalkyl, C3-20 methoxy alkyl glycol ether, C3-20 alkyl glycol ether, or Y-OH moiety; wherein each Y is an independently selected alkylphenol-free moiety that is a C2-40 alkyl, C6-40 cycloalkyl, C2-20 alkyl glycol ether, or C3-40 alkyl lactone moiety; wherein each m is an independently selected integer ranging from 1 to 100; and wherein x is an integer ranging from 1 to 1000.

In some polyhydrogen-phosphite embodiments, such as those having the immediately above chemical structure, each Y is independently selected and is an ethyl, propyl, cyclohexane dimethanol, or caprylactone moiety.

In some polyhydrogen-phosphite embodiments, such as those having the chemical structure: wherein each R is an independently selected alkylphenol-free moiety that is a C1-22 alkyl, C6-40 cycloalkyl, C3-20 methoxy alkyl glycol ether, C3-20 alkyl glycol ether, or Y-OH moiety; wherein each Y is an independently selected alkylphenol-free moiety that is a C2-40 alkyl, C6-40 cycloalkyl, C2-20 alkyl glycol ether, or C3-40 alkyl lactone moiety; wherein each m is an independently selected integer ranging from 1 to 100; and wherein x is an integer ranging from 1 to 1000, the compound has a weight ranging from 1000 to 30000 Daltons. In some polyhydrogenphosphite embodiments, such as those having the immediately above chemical structure, the compound has a weight ranging from 400 to 30000 Daltons. In some polyhydrogen-phosphite embodiments, such as those having the immediately above chemical structure, the compound has a weight ranging from 500 to 30000 Daltons.

A chemical compound having the structure: wherein each R is an independently selected alkylphenol-free moiety that is a C1-22 alkyl, C6-40 cycloalkyl, C3-20 methoxy alkyl glycol ether, C3-20 alkyl glycol ether, or Y-OH moiety; wherein each Y is an independently selected alkylphenol-free moiety that is a C2-40 alkyl, C6-40 cycloalkyl, C2-20 alkyl glycol ether, or C3-40 alkyl lactone moiety; wherein each m is an independently selected integer ranging from 1 to 100; and wherein x is an integer ranging from 1 to 1000, can be obtained commercially from Dover Chemical under the trademark Doverphos LGP-11

Or, it can be manufactured using a known method.

Useful amounts of phosphite antioxidants range from 0.01 to 5.0% by volume of the fluid mixture. Persons of ordinary skill in the art will be able to determine useful amounts of phosphite antioxidants without having to exercise undue experimentation.

Other embodiments include using additional antioxidants, in addition to a phosphite, such as a hindered phenolic or an amine compound.

In embodiments, a composition having: i) a liquid fuel component that is petroleum-based diesel, biodiesel, gasoline, or aviation fuel; and ii) a phosphite antioxidant component, yields reduced unwanted combustion-engine emissions relative to a different composition having a formulation that is otherwise the same but does not include the phosphite antioxidant component.

In embodiments, a composition having: i) a liquid fuel component that is petroleum-based diesel, biodiesel, gasoline, or aviation fuel; and ii) a phosphite antioxidant component having the following chemical structure:

wherein each R ¹ , R ² , R ³ , R ⁴ and R ⁵ is independently selected and is a Cio-Cis alkyl moiety; n is an integer ranging from 3 to 11; and the sum of Xi + X2 is an integer ranging from 1-500, yields reduced unwanted combustion-engine emissions relative to a different composition having a formulation that is otherwise the same but does not include the phosphite antioxidant component.

In embodiments, a composition having: i) a liquid fuel component that is petroleum-based diesel, biodiesel, gasoline, or aviation fuel; and ii) a phosphite antioxidant component having the following chemical structure: wherein each R is an independently selected alkylphenol-free moiety that is a C1-22 alkyl, C6-40 cycloalkyl, C3-20 methoxy alkyl glycol ether, C3-20 alkyl glycol ether, or Y-OH moiety; wherein each Y is an independently selected alkylphenol-free moiety that is a C2-40 alkyl, C6-40 cycloalkyl, C2-20 alkyl glycol ether, or C3-40 alkyl lactone moiety; wherein each m is an independently selected integer ranging from 1 to 100; and wherein x is an integer ranging from 1 to 1000, yields reduced unwanted combustion-engine emissions relative to a different composition having a formulation that is otherwise the same but does not include the phosphite antioxidant component.

In embodiments, a composition having: i) a liquid fuel component that is petroleum-based diesel, biodiesel, gasoline, or aviation fuel; and ii) a phosphite antioxidant component, has inhibited fuel degradation relative to a different composition having a formulation that is otherwise the same but does not include the phosphite antioxidant component.

In embodiments, a composition having: i) a liquid fuel component that is petroleum-based diesel, biodiesel, gasoline, or aviation fuel; and ii) a phosphite antioxidant component having the following chemical structure:

wherein each R ¹ , R ² , R ³ , R ⁴ and R ⁵ is independently selected and is a Cio-Cis alkyl moiety; n is an integer ranging from 3 to 11; and the sum of Xi + X2 is an integer ranging from 1-500, has inhibited fuel degradation relative to a different composition having a formulation that is otherwise the same but does not include the phosphite antioxidant component.

In embodiments, a composition having: i) a liquid fuel component that is petroleum-based diesel, biodiesel, gasoline, or aviation fuel; and ii) a phosphite antioxidant component having the following chemical structure: wherein each R is an independently selected alkylphenol-free moiety that is a C1-22 alkyl, C6-40 cycloalkyl, C3-20 methoxy alkyl glycol ether, C3-20 alkyl glycol ether, or Y-OH moiety; wherein each Y is an independently selected alkylphenol-free moiety that is a C2-40 alkyl, C6-40 cycloalkyl, C2-20 alkyl glycol ether, or C3-40 alkyl lactone moiety; wherein each m is an independently selected integer ranging from 1 to 100; and wherein x is an integer ranging from 1 to 1000, has inhibited fuel degradation relative to a different composition having a formulation that is otherwise the same but does not include the phosphite antioxidant component.

In embodiments, a composition having: i) a liquid fuel component that is petroleum-based diesel, biodiesel, gasoline, or aviation fuel; and ii) a phosphite antioxidant component, has reduced water content relative to a different composition having a formulation that is otherwise the same but does not include the phosphite antioxidant component.

In embodiments, a composition having: i) a liquid fuel component that is petroleum-based diesel, biodiesel, gasoline, or aviation fuel; and ii) a phosphite antioxidant component having the following chemical structure: each R ¹ , R ² , R ³ , R ⁴ and R ⁵ is independently selected and is a Cio-Cis alkyl moiety; n is an integer ranging from 3 to 11; and the sum of Xi + X2 is an integer ranging from 1-500, has reduced water content relative to a different composition having a formulation that is otherwise the same but does not include the phosphite antioxidant component.

In embodiments, a composition having: i) a liquid fuel component that is petroleum-based diesel, biodiesel, gasoline, or aviation fuel; and ii) a phosphite antioxidant component having the following chemical structure: wherein each R is an independently selected alkylphenol-free moiety that is a C1-22 alkyl, C6-40 cycloalkyl, C3-20 methoxy alkyl glycol ether, C3-20 alkyl glycol ether, or Y-OH moiety; wherein each Y is an independently selected alkylphenol-free moiety that is a C2-40 alkyl, C6-40 cycloalkyl, C2-20 alkyl glycol ether, or C3-40 alkyl lactone moiety; wherein each m is an independently selected integer ranging from 1 to 100; and wherein x is an integer ranging from 1 to 1000, has reduced water content relative to a different composition having a formulation that is otherwise the same but does not include the phosphite antioxidant component.

It is believed that at least one of the reaction schemes shown in Figure 1 causes the compositional embodiments to:

1) yield reduced unwanted combustion-engine emissions relative to a different composition having a formulation that is otherwise the same but does not include the phosphite antioxidant component; 2) have inhibited fuel degradation relative to a different composition having a formulation that is otherwise the same but does not include the phosphite antioxidant component; or

3) have reduced water content relative to a different composition having a formulation that is otherwise the same but does not include the phosphite antioxidant component.

EXPERIMENTAL

Figure 1 shows the reaction of alkyl phosphites with hydroperoxides and water. At ambient conditions, if R is an aryl or hindered aryl, a significant amount of reaction with hydroperoxides will not occur. Alkyl phosphites are generally quicker to react with hydroperoxides and water compared to aryl phosphites. It is known that hydroperoxides are both a result of thermal degradation and also promote further degradation of hydrocarbons. Removing hydroperoxides improves fuel quality and thermal stability. Aryl and hindered aryl phosphites do not readily react with hydroperoxides at ambient temperatures (less than 50°C). Hindered aryl phosphites are particularly resistant towards reaction with water. Peroxide Value (PV) is a measurement of the level of hydroperoxides in the sample.

Table 1 displays the peroxide values of a soybean based fatty acid methyl ester and isooctane at ambient conditions (temperatures less than 50°C). The methyl ester is used as an example of biodiesel and the isooctane was used as an example of a hydrocarbon based fuel such as diesel. The initial peroxide value of the methyl ester and isooctane were 6.0 and 18.8 respectively. The addition of an alkyl phosphite (DOVERPHOS LGP-11) scavenged hydroperoxides that were present and reduced the peroxide value to less than 0.5 in both the methyl ester and the isooctane. DOVERNOX 76 is an example of a hindered phenolic stabilizer. They are used to protect hydrocarbons from oxidation, however they cannot remove any hydroperoxides that are initially present. DOVERPHOS S-480 is an example of a hindered aryl phosphite. Neither the DOVERNOX 76 nor the DOVERPHOS S-480 were capable of significantly decreasing the peroxide value, thus indicating their lack of reactivity towards hydroperoxides at ambient conditions. The methyl ester was then heated at 50°C for 48 hours. The peroxide value of the methyl ester increased both with and without the DOVERNOX 76, although the peroxide value was smaller after aging with DOVERNOX 76. The peroxide value of the formulation that contained DOVERPHOS LGP-11 remained less than 0.5. Thus, the addition of an alkyl phosphite improved the quality of the methyl ester/isooctane, and prevented its degradation upon heating.

Table 3 includes data on phosphites in the presence of anhydrous and 95% ethanol. Without any water present, neither the trioctyl phosphite (TOP) nor the hindered aryl phosphite (DOVERPHOS S-480) reacted. Once water was added, the trioctyl phosphite reacted to form the phosphonate. The presence of the phosphonate is an indication of a stoichiometric reaction of the phosphite and water. The hindered aryl phosphite did not react with water and the amount of the phosphite remained constant. Thus the use of an alkyl phosphite to fuel can remove water at ambient conditions and mitigate potential corrosion issues due to the presence of water.

TABLE 1 : Peroxide Values measurements of soybean based fatty acid methyl ester (example of biodiesel) and isooctane (simulant for fuel) mixed at 50°C for 15 minutes. DOVERNOX 76 (common primary hindered phenolic stabilizer). DOVERPHOS S-480 Hindered Aryl Phosphite (tris-2, 4-di-t-butylphenol phosphite). DOVERPHOS LGP-11 Polymeric alkyl phosphite.

Table 2: Peroxide Values measurements of soybean based fatty acid methyl ester after aging at 50° for 48 hours.

Table 3: Alkyl and hindered aryl phosphites in ethanol and ethanol/water. Phosphites were exposed to the solvents for 1 hour.