KR20100115367A - Reduced rvp oxygenated gasoline composition and method - Google Patents

Abstract

A composition of oxygenated gasoline containing isobutanol is disclosed, which does not contain isobutanol and has a reduced vapor pressure as compared to containing only one oxygenate. Such compositions may be formed at refineries or terminals. A method of reducing the vapor pressure of an oxygenated gasoline is disclosed, and a method of reducing the vapor pressure constraint for a refinery in the production of an oxygenated gasoline is disclosed. Basic properties of isobutanol are disclosed, including IR spectral analysis. Processes and methods of blending and dispensing such fuels are also disclosed.

Description

REDUCED RVP OXYGENATED GASOLINE COMPOSITION AND METHOD}

This application claims the benefit of US Provisional Patent Application 61 / 027,969, filed February 12, 2008 and incorporated herein by reference in its entirety.

The present invention relates to oxygenated gasoline, including gasoline containing fuel, more particularly ethanol. The present invention provides an oxygenated gasoline that allows the Reid vapor pressure (RVP) to be reduced to allow higher proportions of low boiling point components to blend into the gasoline without exceeding the RVP limit. The present invention also provides a method of reducing the RVP of an oxygenated gasoline.

Gasoline is suitable for use in spark-ignition engines and is generally a mixture of a plurality of hydrocarbons as primary components, which mixtures have different boiling points and typically range from about 26 ° C. to about 225 ° C. under atmospheric pressure. It is a fuel containing-boiling at temperature. This range is approximate and may vary depending upon the actual mixture of hydrocarbon molecules present, additives (if any) present or other compounds and environmental conditions. Typically, the hydrocarbon component of gasoline contains C ₄ to C ₁₀ hydrocarbons.

Gasoline is typically required to meet certain physical and performance standards. Some characteristics may be implemented for proper operation of the engine or other fuel combustion device. However, many physical and performance characteristics are set by national or regional regulations for other reasons, such as environmental management. Examples of physical properties include RVP, sulfur content, oxygen content, aromatic hydrocarbon content, benzene content, olefin content, temperature at which 90% of the fuel is distilled (T-90), temperature at which 50% of the fuel is distilled (T-50) Etc. are included. Performance characteristics may include octane rating (also called anti-knock index), combustion characteristics, and emission components.

For example, standards for gasoline sold in most of the United States are described in ASTM Standard Specification No. D 4814-01a (“ASTM 4814”), which is generally incorporated herein by reference. Additional federal and state regulations supplement these standards.

Specifications for gasoline described in ASTM 4814 vary based on a number of parameters affecting volatility and combustion, such as climate, season, geographic location and altitude. For this reason, gasoline made in accordance with ASTM 4814 can be classified into the volatility categories AA, A, B, C, D and E, and vapor lock protection categories 1, 2, 3, 4, 5 and 6 Each category has a set of specifications describing gasoline that meets the requirements of each class. These details also describe test methods for measuring parameters within the details.

For example, a class AA-2 gasoline blended for use during summer holidays in a relatively warm climate has a maximum vapor pressure of 54 kPa and a maximum temperature ("T ₁₀ ") for distillation of 10% by volume of its components at 70 ° C. And a temperature range (“T ₅₀ ”) for distillation of 50% by volume of its components is from 77 ° C. to 121 ° C. and a maximum temperature (“T ₉₀ ”) for 90 vol. The end point is 190 ° C., the distillation residue maximum is 2% by volume, and the “Driveability Index” or “DI” maximum temperature is 597 ° C., where DI is 1.5 times T ₁₀ + 3.0 times T ₅₀ . Calculated as + T _90- , the maximum ratio of vapor to liquid should be 20 at a test temperature of 56 ° C.

One physical property of gasoline, covered in ASTM 4814 and commonly controlled in many administrative jurisdictions, is RVP. RVP can be measured according to ASTM Standard Specification D 5191-04a ("D 5191"), which is incorporated herein by reference. RVP standards are typically expressed as maximum RVP limits, which can be forced to meet gasoline commercially available within certain administrative jurisdictions. Such RVP limits significantly limit the composition of hydrocarbons in gasoline because the RVP increases as the proportion of lighter hydrocarbons increases. Typically, to produce gasoline with reduced RVP, the proportion of lighter hydrocarbons, such as C ₄ hydrocarbons, is reduced.

Reducing such lighter hydrocarbons can negatively affect gasoline properties. For example, reducing the amount of butane in gasoline fuel lowers the RVP of that fuel, but it also reduces the octane number.

By limiting the composition of gasoline, the RVP limit also imposes a strain on refinery. In general, refineries adjust the composition of gasoline by controlling the proportion of the various refinery streams used to make gasoline. For example, to produce a higher boiling gasoline, the refinery may need to reduce the proportion of the low boiling refinery stream used to make the gasoline. In order to produce gasoline that will meet applicable RVP limits, refineries typically reduce the proportion of lighter boiling hydrocarbons in gasoline. RVP is typically controlled or adjusted using empirically determined RVP blending values. RVP blend values indicate the contribution of a particular composition to RVP of a particular mixture. One consequence of such RVP constraints on refineries is that less gasoline can be purified from each barrel of petroleum. This can significantly affect the gasoline supply available to meet consumer demand.

The increasing use of oxygenates in gasoline has exacerbated the impact of RVP limits. Oxygenates are used in gasoline to increase the chemical oxygen content. Unfortunately, oxygenates have a nonlinear effect on the RVP when blended into the fuel. Thus, the RVP blending value of the oxygenates is empirically determined for a particular concentration of a particular oxygenate in a particular fuel. Many administrative agencies have oxygenate requirements for gasoline to promote more complete combustion. Methyl-tert-butyl ether (MTBE) was commonly used as gasoline oxygenate. However, many administrative agencies prohibit or severely restrict the use of MTBE and similar ethers.

Due to the limitation on the use of MTBE, other oxygenates of less preferred RVP are typically used for gasoline. Ethanol is widely used as a gasoline oxygenator because of a number of factors, including tax credits provided by many administrative agencies for the use of up to 10% by volume of ethanol in gasoline. US Pat. No. 6,258,987 to Schmidt et al. And US Pat. No. 6,540,797 to Scott et al. Discuss the blending of ethanol in gasoline. Unfortunately, many of the oxygenates allowed for blending into gasoline have significant disadvantages, including affinity for water, which causes transport and handling difficulties and increased RVP of gasoline when blended with such oxygenates. Has Affinity with water causes difficulties in transportation and handling. RVP increases increase the difficulty of producing gasoline within the applicable RVP limits. Ethanol exhibits both of these effects.

With respect to the compositions and methods, there is a need to reduce the deleterious effects that can result from blending oxygenates into gasoline. In particular, it would be desirable to counter at least some of the RVP increase resulting from blending oxygenates into gasoline.

We have found that certain compounds exhibit unexpectedly low RVP blending values in blending with typical oxygenated gasoline. Surprisingly, in some cases, such compounds may even exhibit negative RVP blending values.

The present invention reduces the RVP increase caused by blending oxygenates into gasoline, which allows the refinery to use a higher proportion of low boiling hydrocarbons in the gasoline blend stock, thereby increasing the refinery's gasoline refining capacity. Done. The present invention can be used to reduce the RVP of oxygenated gasoline. In some cases where oxygenated gasoline with an RVP value exceeding the maximum applicable RVP limit is blended, the present invention can be used to ensure that the oxygenated gasoline follows the RVP limit.

We have found that the use of isobutanol can have surprising RVP reduction effects on oxygenated gasoline. Isobutanol can interact with the oxygenates to lower the RVP increase expected from blending the oxygenates with the gasoline blend stock. In some cases, the effect of isobutanol is so dramatic that the RVP reducing compound exhibits a negative RVP blending value.

The present invention provides oxygenated gasoline that can meet applicable RVP limits and still contain larger amounts of lighter components than would otherwise be possible. The present invention allows the supply of gasoline to be increased so that the refinery can use a larger proportion of crude oil for gasoline. The present invention also provides a method of reducing the RVP of an oxygenated gasoline. Such a reduction can be carried out at the terminal and can help reduce the need to obtain a waiver for gasoline, which may otherwise be subject to RVP exceeding regulation. . The present invention also provides a method of reducing RVP constraints on gasoline blend stocks for the blending of oxygenates in the production of oxygenated gasoline for administrative jurisdictions having a maximum RVP limit.

In one embodiment, we provide gasoline containing a gasoline blend stock, a suitable oxygenate and an effective amount of isobutanol. Preferably, the isobutanol has an RVP blend value of less than about 34.5 kPa (5.0 psi), more preferably less than about 20.7 kPa (3.0 psi), and most preferably less than about 0 kPa (0.0 psi). Optionally, the RVP value of the mixture of gasoline blend stock and a suitable oxygenate is at least about 47.6 kPa (6.9 psi). Preferably, the suitable oxygenate is alcohol, more preferably ethanol. Preferably, more than 1% by volume of suitable oxygenate is present. Preferably, less than 20 volume percent isobutanol is present. More than one suitable oxygenate may be used.

In another embodiment, a method of reducing the RVP of an oxygenated gasoline is provided. The method includes blending a gasoline blend stock and one or more suitable oxygenates to form an oxygenated gasoline, and mixing the oxygenated gasoline with isobutanol, wherein the isobutanol has an RVP blend value of about 34.5 kPa ( Less than 5.0 psi), preferably less than 3.0 psi, and most preferably less than about 0 psi (0.0 psi). Suitable oxygenates may be alcohols, preferably ethanol. Either or both of the blending or mixing steps can be performed at the terminal. Optionally, the blending step can be performed concurrently with the mixing step. Preferably, more than 1% by volume of suitable oxygenate is present. Preferably, less than 20% by volume RVP reducing compound is present.

In another embodiment, a method is provided for reducing RVP constraints on gasoline blend stocks in the manufacture of oxygenated gasoline having a predetermined maximum RVP limit. The method comprises blending a gasoline blend stock and one or more suitable oxygenates to form an oxygenated gasoline with an RVP value greater than a predetermined maximum RVP limit, and adding an effective amount of one isobutanol to a predetermined maximum RVP value. Forming gasoline that is less than or equal to the RVP limit. The blending step and the addition step can be performed simultaneously. Suitable oxygenates are preferably ethanol. Preferably, more than 1% by volume of suitable oxygenate is present. Preferably, less than 20% by volume RVP reducing compound is present.

Relative absorbance, further described herein, is a useful method of measuring the effectiveness of isobutanol in reducing RVP. Relative absorbance can also be used to identify oxygenated gasoline that is particularly suitable for reducing RVP using isobutanol. In any embodiment, the gasoline blend stock, one or more suitable oxygenates and isobutanol may be selected such that the normalized relative absorbance of the mixture of gasoline blend stock, suitable oxygenate (s) and isobutanol is less than about 0.045. have. Preferably, the blend of gasoline blend stock and suitable oxygenate (s) has a normalized relative absorbance greater than about 0.05.

Gasoline is well known in the art and generally contains a mixture of hydrocarbons as primary components, which mixtures have different boiling points and typically boil at temperatures ranging from about 26 ° C. to about 225 ° C. under atmospheric pressure. This range is approximate and may vary depending upon the actual mixture of hydrocarbon molecules present, additives (if any) present or other compounds and environmental conditions. Oxygenated gasoline is a blend of gasoline blend stock and one or more oxygenates.

Gasoline blend stocks can be prepared from a single component, for example a product from a refinery alkylation unit or other refinery streams. However, gasoline blend stocks are more generally blended using more than one component.

Gasoline blend stocks are blended to meet desired physical and performance characteristics and to meet regulatory requirements, and may include several such as three or four components, or may include many such as twelve or more components. have.

Gasoline and gasoline blend stocks may optionally include other chemicals or additives. For example, additives or other chemicals can be added to adjust the properties of gasoline to meet regulatory requirements, i.e. add or enhance desired properties, reduce undesirable harmful effects, or modify performance properties. Or otherwise modify the properties of the gasoline. Examples of such chemicals or additives include detergents, antioxidants, stability enhancers, demulsifiers, corrosion inhibitors, metal deactivators, and the like. More than one additive or chemical may be used.

Useful additives and chemicals are described in US Pat. No. 5,782,937 to Colucci et al., Which is incorporated herein by reference. Such additives and chemicals are also described in Wolff, US Pat. No. 6,083,228 and Ishida et al., US Pat. No. 5,755,833, both of which are incorporated herein by reference. Gasoline and gasoline blend stocks may also contain solvent or carrier solutions commonly used to deliver additives into the fuel. Examples of such solvent or carrier solutions include, but are not limited to, mineral oils, alcohols, carboxylic acids, synthetic oils, and many other materials known in the art.

Gasoline blend stocks suitable for the compositions of the present invention are typically blend stocks that can be used to produce gasoline for consumption in spark ignition engines or other engines that burn gasoline. Suitable gasoline blend stocks include blend stocks for gasoline that meet ASTM 4814 and blend stocks for reformed gasoline. Suitable gasoline blend stocks have, for example, less than about 150 ppmv sulfur, more preferably less than about 100 ppmv sulfur, more preferably about 80 ppmv having a low sulfur content that may be required to meet local requirements. Blend stocks with less than sulfur are also included. Such suitable gasoline blend stocks have, for example, less than about 8000 ppmv of benzene, more preferably less than about 7000 ppmv, or further examples having a low aromatic content that may be desirable to meet regulatory requirements. And blend stocks having a total aromatics content of less than about 35% by volume, more preferably a total aromatics content of less than about 25% by volume. As used herein, "total aromatics content" refers to the total amount of all aromatic species present.

As used herein, “oxygen agent” means a C ₂ to C ₈ compound containing only carbon, hydrogen and one or more oxygen atoms. For example, the oxygenate can be an alcohol, ketone, ester, aldehyde, carboxylic acid, ether, ether alcohol, ketone alcohol and polyhydric alcohol. Ethanol is a preferred oxygenate for several reasons, including its widespread availability. As used herein, “suitable oxygenate” means an oxygenate that has a RVP blend value of at least 44.8 kPa (6.5 psi) and is soluble in the particular oxygenated gasoline produced. Preferably, more than about 2 volume percent oxygenate is present.

"RVP blend value" or "blend RVP" is the effective RVP of the composition when blended into the fuel mixture. Blend RVP values represent the contribution of the composition to the RVP of the mixture such that the RVP for the mixture is equal to the sum of the blend RVP of each component multiplied by the volume fraction of those components. For example, for fuel mixtures of [A] and [B], RVP = (volume fraction of blend RVP x [A] of [A]) + (volume fraction of blend RVP x [B] of [B]) to be.

As used herein, a compound is formulated to produce a single liquid phase in a second compound at a desired concentration over the temperature range of interest of the mixture of these compounds, ie, from about −40 ° C. to the starting boiling point of the mixture, unless otherwise noted. If it shows, it can melt | dissolve.

Isobutanol is soluble in the selected oxygenated gasoline and reduces the RVP of the selected oxygenated gasoline that does not contain isobutanol when isobutanol is blended into the selected oxygenated gasoline. The effective RVP reduction of isobutanol is that amount which reduces the RVP of the oxygenated gasoline by at least 0.34 kPa (0.05 psi) relative to the specific RVP reducing compound concentration. RVP can be determined according to ASTM D 5191 using sufficient measurements for statistically significant determination. Preferably the total concentration of isobutanol is less than about 20% by volume, more preferably less than about 10% by volume and most preferably up to about 5% by volume. Isobutanol can be obtained from any suitable source, including by production from biomass. In addition to isobutanol, one or more additional RVP reducing compounds may be added to the mixture with the oxygenated gasoline.

The particular effectiveness of isobutanol in reducing the RVP of oxygenated gasoline is explained by determining the normalized relative absorbance of the mixture of oxygenated gasoline and isobutanol. In addition, suitable oxygenates which are particularly suitable for such particularly effective RVP reduction can be identified by determining the normalized relative absorbance of the oxygenated gasoline (which does not contain isobutanol).

Without being limited to any particular theory, it is believed that isobutanol increases the tendency for the oxygenate to remain liquid, thereby reducing the RVP of the oxygenated gasoline by interacting with the oxygenate in the oxygenated gasoline. Relative absorbance is an analytical technique that can be used to identify suitable oxygenates and isobutanol that are particularly suitable for such interactions with isobutanol leading to a synergistic decrease in RVP.

Relative absorbance is measured using the ASTM Standard Practices for General Techniques of the two-point baseline method, difference method, and infrared quantitation standard E 168-99 ("E 168"). General Techniques of Infrared Quantitative Analysis Specification E 168-99, which is incorporated herein by reference.

The relative absorbance of the mixture containing isobutanol and oxygenated gasoline is obtained using the difference spectrum obtained by subtracting the absorbance spectrum of the oxygenated gasoline without any suitable oxygenate from the absorbance spectrum of the mixture and It is determined using a two-point baseline method that calculates the ratio of the band area of 3680 cm ^-1 to 3550 cm ^{-1 to} the band area of 3680 cm ^-1 to 3100 cm ^-1 . The use of the difference spectrum as described minimizes the variability due to the use of different gasoline blend stocks.

The relative absorbance of oxygenated gasoline is obtained using the difference spectrum obtained by subtracting the absorbance spectrum of the oxygenated gasoline containing no suitable oxygenate from the absorbance spectrum of the oxygenated gasoline and the band area of 3680 cm ^-1 to 3550 cm ^-1 . Is determined using a two-point baseline method that calculates the ratio of the band area of 3680 cm ⁻¹ to 3100 cm ⁻¹ .

Table I below shows the relative absorbances of some oxygenated gasoline with different concentrations of the oxygenate compound of one of the replaceable unleaded ordinary gasoline that meets ASTM D 4814.

TABLE I

As shown in Table I, the relative absorbance changes with concentration. Table I also demonstrates the nonlinearity between relative absorbance and concentration. Relative absorbance will generally be determined empirically. For the particular unleaded ordinary gasoline used in Table I, ethanol will be a suitable oxygenate compound for this particular embodiment of the present invention.

Table II shows the relative absorbances of several mixtures of oxygenated gasoline and isobutanol with the same replaceable lead-free regular gasoline used in Table I.

[Table II]

As illustrated in Table I, the addition of isobutanol into the oxygenated gasoline has a significant impact on the relative absorbance of the mixture. This effect varies with different concentrations of isobutanol, but such a change in relative absorbance indicates a synergistic interaction between the components, which leads to a surprising RVP reduction effect.

In some embodiments, the normalized relative absorbance of the mixture containing isobutanol and oxygenated gasoline is less than about 0.045, preferably less than about 0.030. Preferably, the at least one suitable oxygenate is selected such that the normalized relative absorbance of the oxygenated gasoline containing such suitable oxygenate (s) (without isobutanol) is greater than about 0.05 and preferably greater than about 0.1. do.

The term "normalized relative absorbance" of a mixture containing isobutanol and oxygenated gasoline is defined as the relative absorbance of the mixture when isobutanol is present in the mixture in greater than about 0.5% by weight at the desired concentration of a suitable oxygenate.

The normalized relative absorbance of oxygenated gasoline (without isobutanol) is determined by calculating the relative absorbance when a suitable oxygenate is present at about 1.0% by weight in the oxygenated gasoline.

In another embodiment, the oxygenated gasoline comprises a gasoline blend stock, one or more suitable oxygenates, and a blend of isobutanol. In another embodiment, the oxygenated gasoline is a blend of gasoline blend stock, one or more suitable oxygenates, including ethanol, and isobutanol.

Some properties of gasoline blend stocks and mixtures of oxygenates, isobutanol or both do not vary linearly with respect to the amount of each component used. In particular, the volatility related properties of such mixtures may deviate from linear proportions with respect to the amount of each component used. This nonlinear effect has made it particularly difficult to predict the actual effect of oxygenates in gasoline on RVP. The actual RVP of oxygenated gasoline varies depending on the gasoline blend stock used, the specific oxygenate used and the concentration of oxygenate in the oxygenated gasoline. Due to this nonlinear variability, the RVP of oxygenated gasoline is determined empirically. RVP data is typically collected empirically over a range of oxygenate concentrations and over a range of gasoline blend stocks.

Typically, the blend RVP of the oxygenate is calculated by measuring the RVP of the fuel before the addition of such oxygenate and after the addition of such oxygenate. Oxygen blend RVP values that can be calculated from such empirical data also exhibit nonlinear behavior with respect to the concentration of oxygenates in certain oxygen gasoline, which makes it difficult to predict such blend RVP values. Due to such nonlinear effects on RVP, the calculated blend RVP values are specific for the concentration of the specific oxygenate added to the particular fuel.

Blend RVP of isobutanol exhibits nonlinear behavior when calculated as a function of volume fraction of isobutanol, which makes the prediction of the RVP of the resulting mixture more difficult. Typically, the blend RVP of isobutanol is calculated by measuring the RVP of the fuel before addition of isobutanol and after addition of isobutanol. Since isobutanol exhibits a non-linear effect on RVP when added to the fuel, the measured blend RVP is specific to the concentration of isobutanol added to the particular fuel.

The inventors have surprisingly found that a combination of one or more suitable oxygenates and isobutanol can have a synergistic effect on the RVP value of the gasoline produced.

In any embodiment, the gasoline blend stock, suitable oxygenates and isobutanol may be blended in any order. For example, isobutanol can be added to a mixture comprising a gasoline blend stock and a suitable oxygenate. As another example, one or more suitable oxygenates and isobutanol may be added at several different locations or at multiple stages. As a further example, isobutanol can be added with a suitable oxygenate, added before a suitable oxygenate, or blended with a suitable oxygenate before being added to the gasoline blend stock. In a preferred embodiment, isobutanol is added to the oxygenated gasoline. In another preferred embodiment, one or more suitable oxygenates and isobutanol are blended into the gasoline blend stock at the same time.

In any embodiment, more than one suitable oxygenate may be used in place of only one suitable oxygenate. Suitable oxygenates and isobutanol may be added at any point in the distribution chain. For example, gasoline blend stock may be transported to a terminal, and suitable oxygenates and isobutanol may then be blended with the gasoline blend stock individually or in combination at the terminal. As a further example, gasoline blend stocks, one or more suitable oxygenates and isobutanol may be combined in the refinery. Other components or additives may be added at any point in the distribution chain.

In yet another embodiment, a method of reducing the RVP of an oxygenated gasoline is provided. This method can be implemented at a refinery, terminal, retail store, or any other suitable point in the distribution chain. Preferably, the method is carried out at a terminal already scheduled to blend ethanol or some other oxygenate with the gasoline blend stock or at a terminal that can be configured to accommodate such blending.

According to another embodiment, the gasoline blend stock is an oxygenated gasoline fuel having a lower RVP than ethanol, other suitable oxygenates or a combination of suitable oxygenates, and oxygenated gasoline that is blended with isobutanol and does not contain isobutanol. Create

The blend RVP value of isobutanol is less than the RVP value of the rest of the mixture. Preferably, the blend RVP of isobutanol is at most about 50% of the RVP of the remaining mixture. Alternatively, the blend RVP of isobutanol is about 34.5 kPa (5.0 psi), more preferably less than about 20.7 kPa (3.0 psi), and more preferably less than about 0 kPa (0.0 psi).

Regulations for gasoline set limits on various properties of the fuel, which typically include an upper limit for RVP. Such RVP limits may vary by country, region and season. Such RVP limits place constraints on the refinery product that can be used as gasoline. Typically, the oxygenate will raise the RVP of the resulting blend when blended into the gasoline blend stock. Typically, gasoline blend stocks for blending of oxygenates have an RVP sufficiently lower than any applicable upper limit to account for the expected effects of oxygenates. This further constrains the refinery product that can be used for gasoline because less high volatile fuel components can be used in the gasoline blend stock. Such RVP constraints may limit the amount of gasoline available for consumption.

In another embodiment, a method is provided for reducing RVP constraints on refiners that produce gasoline blend stocks for blending of oxygenates. RVP constraints on refineries are reduced because oxygenated gasoline following the regulatory RVP limits can be generated using gasoline blend stocks that would otherwise not be available to produce RVP compliant oxygenated gasoline. Another embodiment provides a method of reducing the RVP of an oxygenated gasoline, such that any oxygenated gasoline that would otherwise have not been able to meet the regulatory RVP limit can be blended to follow that regulatory RVP limit.

In another embodiment, oxygenated gasoline is prepared by blending selected gasoline blend stocks, selected suitable oxygenates and isobutanol to form oxygenated gasoline. Isobutanol reduces the RVP value of oxygenated gasoline. For certain suitable oxygenates and certain gasoline blend stocks, the use of isobutanol may result in the use of gasoline blend stocks having higher RVP values than could typically be used to produce oxygenated gasoline that meets applicable RVP regulations. It can be used.

For a given maximum RVP value, gasoline blend stocks and suitable oxygenates are used, even if the RVP values of the mixture of gasoline blend stocks and suitable oxygenates exceed the maximum RVP values, gasoline blend stocks, suitable oxygenates and isobutanol The RVP value of the oxygenated gasoline mixture containing is selected to be less than or equal to the maximum RVP value.

Without limiting the scope, the following examples illustrate various embodiments of the invention. Although the specific examples below are discussed in connection with unleaded gasoline fuels that meet the performance characteristics of ASTM D4814, the present invention is not limited to such fuels and may be used for any gasoline blend stock or fuel consistent with the description herein. It will be appreciated by those skilled in the art that the present invention may be employed.

Example

A lead-free general gasoline blend stock that meets the performance characteristics of ASTM D4814-01a was blended with 10 volume percent of a suitable oxygenate. Ethanol was used as a suitable oxygenate. The RVP of the resulting oxygenated gasoline was determined to be 66.8 kPa (9.69 psi) as measured according to ASTM D5191. Isobutanol (14 vol%) was blended with oxygenated gasoline and the resulting mixture had an RVP of 59.6 kPa (8.64 psi) as measured according to ASTM D5191. The calculated blend RVP value for the 14 volume% blend was 15.1 kPa (2.19 psi).

The above examples show how isobutanol can reduce the RVP of oxygenated gasoline. In areas with a maximum RVP limit, the refinery typically predicts an increase in RVP from the blending of the oxygenates resulting in gasoline blend stocks significantly below that limit. Since isobutanol can be used to reduce the RVP of oxygenated gasoline, the refiner can use a gasoline blend stack to produce oxygenated gasoline following the applicable RVP limits, otherwise this gasoline blend stock is RVP compliant. It could not be used to produce oxygen gasoline.

Claims (37)

(a) gasoline blend stocks;
(b) suitable oxygenates; And
(c) isobutanol in an amount effective to reduce the RVP of oxygenated gasoline that does not contain isobutanol
Gasoline composition comprising a. The gasoline composition of claim 1, wherein the isobutanol has a RVP blend value of less than about 34.5 kPa (5.0 psi). The gasoline composition of claim 2, wherein the isobutanol has an RVP blend value of less than about 0 psi. The gasoline composition of claim 1 or 2, wherein the RVP value of the mixture of gasoline blend stock and a suitable oxygenate is at least about 47.6 kPa (6.9 psi). The gasoline composition of claim 1, wherein the suitable oxygenate is alcohol. 6. The gasoline composition of claim 5, wherein the suitable oxygenate is ethanol. The gasoline composition of claim 6, wherein the ethanol is present at least about 1 volume percent. 8. The gasoline composition of claim 7, wherein the isobutanol is present in less than about 20 volume percent. The gasoline composition of claim 8, wherein the ethanol is present at up to 20% by volume and the isobutanol is present from about 1% to about 20% by volume. The gasoline composition of claim 1, wherein the blend of gasoline blend stock and a suitable oxygenate has a normalized relative absorbance greater than about 0.05. The gasoline composition of claim 10, wherein the mixture of gasoline blend stock, suitable oxygenate and isobutanol has a normalized relative absorbance of less than about 0.045. The gasoline composition of claim 11, wherein the isobutanol has an RVP blend value of less than about 34.5 kPa (5.0 psi). 13. The gasoline composition of claim 11 or 12, wherein the RVP value of the mixture of gasoline blend stock and suitable oxygenate is at least about 6.9. The gasoline composition of claim 10, wherein the suitable oxygenate is ethanol. A method of reducing the RVP of an oxygenated gasoline comprising blending a gasoline blend stock, a suitable oxygenate and an amount of isobutanol effective to reduce the RVP. The method of claim 15, wherein the isobutanol has an RVP blend value of less than about 34.5 kPa (5.0 psi). The method of claim 16, wherein the isobutanol has an RVP blend value of less than about 0 psi. 18. The method of claim 15 or 17, wherein the RVP value of the mixture of gasoline blend stock and a suitable oxygenate is at least about 47.6 kPa (6.9 psi). The method of claim 15, wherein the suitable oxygenate is ethanol. The method of claim 19, wherein ethanol is present at up to 20% by volume and isobutanol is present in about 1% to about 20% by volume in the resulting composition. The method of claim 15, wherein at least one of the suitable oxygenate or isobutanol is blended at the terminal. The method of claim 15, wherein the suitable oxygenate and isobutanol are blended with the gasoline blend stock at the same time. The method of claim 15, wherein the mixture of gasoline blend stock and a suitable oxygenate has a normalized relative absorbance greater than about 0.05. The method of claim 23, wherein the mixture comprising isobutanol, gasoline blend stock, and a suitable oxygenate has a normalized relative absorbance of less than about 0.045. A method of reducing RVP constraints on gasoline blend stocks in the production of oxygenated gasoline with a predetermined maximum RVP limit, the method comprising: blending a gasoline blend stock, a suitable oxygenate and an amount of isobutanol effective to reduce RVP A mixture of gasoline blend stock and a suitable oxygenate has an RVP value greater than a predetermined maximum RVP limit, and a mixture of gasoline blend stock, a suitable oxygenate and isobutanol has an RVP value less than a predetermined maximum RVP limit or Same way. The method of claim 25, wherein the suitable oxygenate and isobutanol are blended with the gasoline blend stock at the same time. The method of claim 25, wherein the isobutanol is blended with the gasoline blend stock before the suitable oxygenate is blended with the gasoline blend stock. The method of claim 25, wherein at least one of the suitable oxygenates or isobutanol is blended at the terminal with the gasoline blend stock. The method of claim 25, wherein the suitable oxygenate is ethanol. The method of claim 29, wherein the ethanol is present at least 1% by volume in the resulting composition. The method of claim 30, wherein the isobutanol is present in less than about 20 volume percent in the resulting composition. The method of claim 31, wherein ethanol is present in about 1% by volume to about 20% by volume and isobutanol is present in about 1% by volume to about 20% by volume in the resulting composition. The method of claim 25, wherein the oxygenated gasoline has a normalized relative absorbance greater than about 0.05. The method of claim 33, wherein the mixture comprising isobutanol and oxygenated gasoline has a normalized relative absorbance of less than about 0.045. The method of claim 34, wherein the suitable oxygenate in the resulting composition is present in greater than about 1 vol% and the isobutanol is present in less than about 20 vol%. The gasoline composition of claim 25, wherein the isobutanol has an RVP blend value of less than about 34.5 kPa (5.0 psi). The gasoline composition of claim 36, wherein the isobutanol exhibits an RVP blend value of less than about 0 psi.