MX2010008747A - Reduced rvp oxygenated gasoline composition and method. - Google Patents

Abstract

Compositions of oxygenated gasolines containing isobutanol are disclosed that have reduced vapor pressure compared to those containing a single oxygenate and no isobutanol. Such compositions can be formed at a refinery or at a terminal. Methods of reducing vapor pressure of an oxygenated gasoline are disclosed and methods of reducing vapor pressure constraints upon a refinery in the production of oxygenated gasoline are disclosed. Fundamental properties of isobutanol are disclosed inctuding IR spectrum analysis. Processes and methods for blending and distributing these fuels are also disclosed.

Description

COMPOSITION OF OXYGENATED GASOLINE WITH STEAM PRESSURE REDUCED (PVR) AND METHOD BACKGROUND OF THE INVENTION This invention relates to fuels, more particularly, to oxygenated gasolines that include gasolines containing ethanol. This invention provides an oxygenated gasoline having a reduced Reid vapor pressure (PVR), thereby allowing a higher proportion of low boiling components to be mixed in the gasoline without exceeding the PVR limits. This invention also provides a method for reducing the PVR of oxygenated gasolines.

Gasolines are fuels that are suitable for use in spark ignition engines and which generally contain as a primary component a mixture of numerous hydrocarbons having different boiling points and typically boiling at a temperature in the range of about 26. ° C at about 225 ° C under atmospheric pressure. This range is approximate and may vary depending on the actual mixture of hydrocarbon molecules present, additives-or other compounds present (if any), and environmental conditions. Usually, the hydrocarbon component of gasoline contains C4 to C14 hydrocarbons.

Usually, gasoline is required to meet certain physical and performance standards. Some REF.:212894 Features can be implemented for the proper operation of engines or other fuel combustion appliances. However, many physical and performance characteristics are established by regional or national regulations for other reasons, such as environmental management. Examples of physical characteristics include PVR, sulfur content, oxygen content, aromatic hydrocarbon content, benzene content, olefin content, temperature at which 90 percent of the fuel is distilled (T-90), temperature in the which 50 percent of the fuel is distilled (T-50) and others. Performance characteristics may include octane (also called antiknock index), combustion properties, and emission components.

For example, standards for gasoline for sale in much of the United States are generally set forth in the standard specification number ASTM D 4814-Ola ("ASTM 4814"), which is incorporated herein by reference. Additional state and federal regulations supplement this standard.

The specifications for gasoline set forth in ASTM 4814, vary based on a number of parameters that affect volatility and combustion, such as climate, season, geographic location and altitude. For this reason, gasolines produced in accordance with ASTM 4814 are broken down into Volatility categories AA, A, B, C, D and E, and vapor closure protection categories 1, 2, 3, 4, 5, and 6, each category has a series of specifications that describe gasoline that meet the requirements of the respective classes. This specification also establishes the methods to determine the parameters in the specification.

For example, a gasoline class AA-2 mixed to be used during the summer handling season in relatively hot climates, should have a maximum steam pressure of 54 kPa, a maximum temperature for distillation of 10% of the volume of its components (the "Ti0") of 70 ° C, a temperature range for distillation of 50% of the volume of its components (the "T50" ') between 77 ° C and 121 ° C, a maximum temperature for distillation of 90% of the volume of its components (the "T90") of 190 ° C, a final distillation point of 190 ° C, a maximum distillation residue of 2% of the volume, an "index of maneuverability" or "IM" of maximum temperature of 597 ° C, where the MI is calculated as 1.5 times the T10 plus 3.0 times the T50 plus the T90, and a maximum vapor-to-liquid ratio of 20 at a test temperature of 56 ° C.

PVR is a physical characteristic of gasoline, which is presented in ASTM 4814 and is commonly regulated in many jurisdictions. The PVR can be measured according to the standard specification ASTM D 5191-04a ("D 5191"), incorporated as reference herein. PVR standards are typically expressed as a maximum PVR limit that commercially sold gasolines in a particular jurisdiction are required to satisfy. Such PVR limits significantly restrict the composition of hydrocarbons in gasoline because PVR increases as the proportion of lighter hydrocarbons increases. Usually, to produce gasoline with reduced PVR, the proportion of lighter hydrocarbons, eg, C4 hydrocarbons, is reduced.

The reduction of these lighter hydrocarbons can have a negative impact on the characteristics of gasoline. For example, decreasing the amount of butane in a gasoline fuel decreases the PVR of that fuel, but also reduces the octane rating.

By restricting the composition of gasoline, the limits of the PVR also impose a burden on the refineries. Generally, refineries adjust the composition of gasoline by controlling the proportions of several refinery streams, which are used to produce the gasoline. For example, to produce a gasoline with a higher boiling point, a refinery may need to reduce the proportion of refinery currents from low boiling points, used to produce gasoline. To produce gasolines that meet the applicable PVR limits, refineries, typically, they reduce the proportion of lighter boiling hydrocarbons in gasolines. Usually, the PVR is controlled or adjusted using empirically determined PVR mixing values. A PVR mixing value represents a particular composition contribution to the PVR of a particular mixture. One consequence of such PVR restrictions on refineries is that less gasoline can be refined from each barrel of oil. This can significantly affect the supply of gasoline available to meet consumer demand.

The impact of the PVR limits has intensified due to the increased use of oxygenates in gasolines. Oxygenates are used in gasolines to increase the chemical oxygen content. Unfortunately, oxygenates have a non-linear effect on PVR when mixed in a fuel. Therefore, the PVR mixing values of oxygenates are determined empirically for a particular concentration of a particular oxygenate in a particular fuel. Many jurisdictions have oxygenate requirements to promote more complete combustion. Methyl-tert-butyl ether (MTBE) was commonly used as an oxygenate of gasoline. However, many jurisdictions prohibit or severely limit the use of MTBE and similar ethers.

Due to restrictions in the use of MTBE, other oxygenates with less favorable PVR are typically used in gasolines Ethanol is widely used as a gasoline oxygenate, due to a number of factors including, tax credits offered by many jurisdictions to use up to 10% by volume of ethanol in gasoline. United States Patent Nos. 6,258,987 by Schmidt et al. and 6,540,797 to Scott et al., which are incorporated by reference herein, describe mixing ethanol in gasolines. Unfortunately, many of the oxygenates allowed for mixing in gasolines have significant major impairments that include, an affinity for water, which causes transport and handling difficulties, and an increase in a PVR of gasoline when mixed with oxygenate. An affinity for the water causes transport and handling difficulties. The increase in PVR extends the difficulty to produce gasoline within the applicable PVR limits. Ethanol has both of the effects mentioned above.

There is a need for a composition or method to diminish the pericial effects produced by the mixture of oxygenates in gasolines. In particular, it would be convenient to have at least some of the increase in PVR attributable to the mixing of oxygenates in gasolines.

It has been found that a certain compound has unexpectedly low PVR mixing values for mixing with typical oxygenated gasolines. Surprisingly, in some cases, this compound can still exhibit values of mixed PVR negative.

This invention decreases the increase in PVR attributable to the mixing of oxygenates in gasolines, which allows refineries to use a higher portion of low boiling hydrocarbons in gasoline blending reserves, therefore increasing the refining capacity of gasoline. of the refinery. This invention can be used to reduce the PVR of an oxygenated gasoline. This invention can be used to make oxygenated gasoline meet the PVR limit, in certain cases, where a mixed oxygenated gasoline has a PVR value that exceeds the applicable maximum PVR limit.

BRIEF DESCRIPTION OF THE INVENTION It has been found that the use of isobutanol can have a reducing effect of PVR on oxygenated gasolines. Isobutanol can interact with an oxygenate to decrease the expected PVR increase of the oxygenate mixture with a gasoline mixture reserve. In some cases, the effect of isobutanol is so dramatic that the PVR reducing compound presents a negative PVR mixing value.

This invention provides an oxygenated gasoline, which can satisfy an applicable PVR limit, and may even, include a larger amount of lighter components than would otherwise be possible. This invention allows a refinery to use a larger proportion of crude oil for gasoline, therefore, it increases the supply of gasoline. This invention also provides a method for reducing the PVR of an oxygenated gasoline. This reduction can be done in a terminal and can help reduce the need to obtain exceptions for gasoline which may otherwise have a PVR that exceeds the regulations. This invention also provides a method for reducing the restrictions of PVR on gasoline blending fuels to mix oxygenates in the production of oxygenated gasolines for jurisdictions having a maximum PVR limit.

In one embodiment, a gasoline containing a stock of gasoline mixture, a suitable oxygenate, and an effective amount of isobutanol is provided. Preferably, the isobutanol has a PVR blend value 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 PVR value of a mixture of the gasoline mixture stock and the appropriate oxygenate is at least about 47.6 kPa (6.9 psi). Preferably, the suitable oxygenate is an alcohol, more preferably ethanol. Preferably, more than 1% by volume of suitable oxygenates is present. Preferably, less than 20% by volume of isobutanol is present. More than one suitable oxygenate can be used.

In another embodiment, a method is provided for reduce the PVR of an oxygenated gasoline. The method includes a step of combining a stock of gasoline mixture and one or more suitable oxygenates to form an oxygenated gasoline, and the step of mixing oxygenated gasoline and isobutanol, characterized in that in addition the isobutanol has a lower PVR blend value than about 34.5 kPa (5.0 psi), preferably less than about 20.7 kPa (3.0 psi) and most preferably less than about 0 kPa (0.0 psi). The suitable oxygenate can be an alcohol, preferably ethanol. Either or both of the mixing or combining steps may be carried out in a terminal. Optionally, the combining step can be carried out contemporaneously with the mixing step. Preferably, more than 1% by volume of suitable oxygenates is present. Preferably, less than 20% by volume of PVR reducing compounds is present.

In another embodiment, a method is provided for reducing the PVR restriction in a gasoline blending stock in the production of oxygenated gasolines with a predetermined maximum PVR limit. The method includes the step of combining a gasoline blending stock and one or more suitable oxygenates to form an oxygenated gasoline with a PVR value greater than the predetermined maximum PVR limit, and the step of adding an effective amount of an isobutanol to form a gasoline that has a PVR value less than or equal to maximum predetermined PVR limit. The mixing stage and the addition stage can be carried out contemporaneously. Preferably, the suitable oxygenate is ethanol. Preferably, more than 1% by volume of suitable oxygenates is present. Preferably, less than 20% by volume of PVR reducing compounds is present.

The relative absorbance, as described further herein, is a useful way to measure the efficacy of isobutanol to reduce PVR. The relative absorbance can also be used to identify oxygenated gasolines, which are particularly treatable for the reduction of PVR using isobutanol. In any embodiment, a gasoline blending stock, one or more suitable oxygenates and one or more PVR reducing compounds can be selected such that a stock mixture of suitable gasoline, oxygenate (s) and compound (s) ) of PVR, have a normalized relative absorbance of less than about 0.045. Preferably, a suitable gasoline and oxygenate (s) mixture stock has a normalized relative absorbance greater than about 0.05.

DETAILED DESCRIPTION OF THE INVENTION Gasolines are well known in the art and generally contain as a primary component a mixture of hydrocarbons having boiling points different and, typically, boil at a temperature in the range of about 26 ° C to about 225 ° C under atmospheric pressure. This range is approximate and may vary depending on the actual mixture of hydrocarbon molecules present, additives and other compounds present (if any), and environmental conditions. Oxygenated gasolines are a mixture of a mixture of gasoline and one or more oxygenates.

The gasoline blending reserve can be produced from a single component, such as the product of a refinery alkylation unit or other refinery streams. However, gasoline blending reserves are commonly mixed using more than one component.

The gasoline blending reserves are mixed to meet the desired physical properties and performance characteristics and meet the regulatory requirements and may involve some components, for example, three or four, or may involve many components, for example, twelve or more.

Gasoline and gasoline blending reserves, optionally, may include other chemicals or additives. For example, additives or other chemicals can be added to adjust the properties of a gasoline to meet regulatory requirements, add or improve desirable properties, reduce harmful effects undesirable, adjust performance characteristics, or otherwise, modify the characteristics of gasoline. Examples of these chemicals or additives include detergents, antioxidants, stability enhancers, demulsifiers, corrosion inhibitors, metal deactivators and others. More than one additive or chemical can be used.

Useful additives and chemicals are described in U.S. Pat. 5,782,937 to Colucci et al., Which is incorporated herein by reference. Such additives and chemicals are also described in U.S. Pat. 6,083,228 of olf and in U.S. Patent No. 5,755,833 from Ishida et al. both incorporated as reference in the present. Gasoline and gasoline blending reserves may also contain carrier or solvent solutions, which are often used to supply the additives in a fuel. Examples of these solvents or carrier solutions include, but are not limited to, mineral oil, alcohols, carboxylic acids, synthetic oils, and numerous others that are known in the art.

Gasoline blending reserves suitable for the composition of this invention are typically gasoline blending fuels usable for preparing gasolines for consumption in spark ignition engines or in other engines that combust gasoline. The reserves of mixture of Suitable gasoline include blending fuels for gasoline that meet ASTM 4814 and blending fuels for reformulated gasoline. Suitable gasoline blending reserves further include blending fuels that have a low sulfur content, which may be desirable to meet regional requirements, for example, they have less than about 150 ppmv sulfur, more preferably less than about 100. ppmv of sulfur, more preferably less than about 80 ppmv of sulfur. Suitable gasoline blending reserves further include blending fuels that have low aromatics content, which may be desirable to meet regulatory requirements, for example, they have less than about 8000 ppmv of benzene, more preferably less than about 7000 ppmv of benzene, or as another example, have less than about 35% by volume of total aromatics content, more preferably less than about 25% by volume of total aromatics content. As used herein, "total aromatics content" refers to the total amount of all aromatic species present.

"Oxygenate" as used herein, means a C2 to C8 compound that contains only carbon, hydrogen and one or more oxygen atoms. For example, oxygenates can be alcohols, ketones, esters, aldehydes, acids carboxylics, ethers, ether alcohols, ketone alcohols and polyalcohols. Ethanol is a preferred oxygenate for several reasons including its extended availability. As used herein, "suitable oxygenate" means an oxygenate having a PVR blend value of at least 44.8 kPa (6.5 psi) and that is soluble in the particular oxygenated gasoline to be produced. Preferably, more than about 2% by volume of oxygenate is present.

"PVR mixing value" or "mixing PVR" is the effective PVR of a composition when mixed in a fuel mixture. A PVR value of the mixture represents the contribution of the composition to the PVR of a mixture, such that the PVR for the mixture is equal to the sum of each PVR of the component mixture, multiplied by that of the volume fraction of the component. For example, for a fuel mixture of [A] and [B], the PVR = (PVR of mixture of [A] x volume fraction of [A]) + (PVR of mixture of [B] x volume fraction of [B]).

As used herein, a compound is soluble in a second compound if a mixture of the compounds exhibits a single liquid phase in the desired concentrations over the temperature range of interest, unless stated otherwise, is approximately -40 ° C to the initial boiling point of the mixture.

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

The special efficacy of isobutanol to reduce the PVR of oxygenated gasolines is illustrated by determining the normalized relative absorbance of a mixture of oxygenated gasoline and isobutanol. Additionally, suitable oxygenates that are particularly treatable at such particularly effective reduction of PVR can be identified by determining the relative absorbance standardized oxygenated gasoline (without isobutanol).

Without being limited by any particular theory, it is believed that isobutanol interacts with oxygenates in an oxygenated gasoline and increases the tendency of oxygenate to remain in the liquid phase, therefore, it reduces the PVR of oxygenated gasoline. Relative absorbance is an analytical technique that can be used to identify suitable oxygenates and PVR reducing compounds, which are particularly treatable at such interactions which produce a synergistic reduction of PVR.

The relative absorbance employs the two-point baseline method, the difference method, and infrared quantitative analysis techniques, as described in the Standard Practices for General Techniques of Specification of Quantitative Infrared Analysis of ASTM E 168-99 ("E 168"), incorporated as reference herein.

The relative absorbance of a mixture containing isobutanol and oxygenated gasoline is determined using the difference spectrum obtained by subtracting the absorbance spectrum of oxygenated gasoline without any suitable oxygenate from the absorbance spectrum of the mixture and using the line method two point basis, to calculate 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 spectrum of difference as described, minimizes the variability due to the use of different gasoline blending fuels.

The relative absorbance of an oxygenated gasoline is determined using the spectrum of difference obtained by subtracting the absorbance spectrum of oxygenated gasoline, without the adequate oxygenate from the absorbance spectrum of oxygenated gasoline and using the two-point baseline method, to calculate the ratio of the band area from 3680 cnf1 to 3550 was "1, the band area of 3680 was" 1 to 3100 cm "1.

Table I below shows the relative absorbance of several oxygenated gasolines having different concentrations of an oxygenate compound in a regular gasoline without fungible lead that meets ASTM D 4814.

Table I Relative absorbance of ethanol at varying concentrations in regular unleaded gasoline Absorbance Concentration Compound Oxygenate% relative weight Ethanol 1.05 0.104 Ethanol 2.11 0.049 Ethanol 5 27 • 0 009 Isobutanol 1 01 0 662 Isobutanol 2 00 0 137 Isobutanol 5 00 0 038 As shown in Table I, the relative absorbance varies by concentration. Table I also demonstrates the non-linearity between the relative absorbance and the concentration. The relative absorbance will generally be determined empirically. For the particular unleaded regular gasoline used in Table I, ethanol could be an oxygenate suitable for this particular embodiment of the invention.

Table II shows the relative absorbance of several isobutanol samples and one oxygenated gasoline with the same regular gasoline without fungible lead used for Table I.

Table II Relative absorbance of isobutanol in an oxygenated gasoline (2% by weight of ethanol) Reducing compound of PVR Concentration Absorbance % relative weight None 0 049 Isobutanol 2.0 0 029 As illustrated in Table I, the addition of isobutanol in oxygenated gasoline has a significant impact on the relative absorbance of the mixture. The impact varies with different concentrations of isobutanol, but such changes in relative absorbance indicate a synergistic interaction between the components that result in a surprising PVR reducing effect.

In some embodiments, the relative absorbance of a mixture of isobutanol and oxygenated gasoline is less than about 0.045, preferably less than about 0.030. Preferably, one or more suitable oxygenates are selected so that the normalized relative absorbance of an oxygenated gasoline containing suitable oxygenate (s), (without isobutanol) is greater than about 0.05, preferably greater than about 0.1.

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

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

In another embodiment, oxygenated gasoline includes a mixture of gasoline blending fuels, one or more suitable oxygenates, and isobutanol. In another embodiment, oxygenated gasoline is a mixture of gasoline blending fuels, one or more suitable oxygenates that include ethanol, and isobutanol.

Some properties of fuel blends of gasoline blends with oxygenates, PVR reducing compounds or both do not vary linearly with the amount of each component used. In particular, the characteristics related to the volatility of such mixtures may diverge from the linear proportionality with respect to the amount of each component used. This non-linear effect has made it particularly difficult to predict the real impact on the PVR of oxygenates in gasoline. The actual PVR of an oxygenated gasoline varies with the stock of used gasoline mixture, the particular oxygenate used, and the specific concentration of oxygenate in oxygenated gasoline. Due to this non-linear variability, the PVR of an oxygenated gasoline is determined empirically. The PVR data are gathered empirically in a range of oxygenated concentrations and in a range of gasoline blending fuels.

The PVR of the mixture of an oxygenate, is typically calculated by measuring the PVR of a fuel before the addition of such oxygenate and after the addition of such oxygenate. The PVR values of oxygenate mixture, which can be calculated from such empirical data, also exhibit non-linear behavior with respect to the concentration of oxygenate in the particular oxygenated gasoline, making such PVR values of the mixture difficult to predict. Due to such nonlinear effects on the PVR, the calculated PVR value of the mixture is particular to the concentration of a particular oxygenate added to a particular fuel.

The PVR of the isobutanol mixture when calculated as a function of the volume fraction of isobutanol exhibits a non-linear behavior, which makes it more difficult to predict the PVR of the resulting mixture. The PVR of the isobutanol mixture is typically calculated by measuring the PVR of a fuel before the addition of isobutanol and after the addition of isobutanol. Because isobutanol exhibits a nonlinear effect on PVR when added to a fuel, the PVR of the measured mixture is particular to the concentration of isobutanol added to the particular fuel.

It has surprisingly been found that the combination of one or more suitable oxygenates and isobutanol can have a synergistic effect on the PVR value of the gasoline to be produced.

In any modality, the mixture reserve of gasoline, suitable oxygenates and isobutanol, can be mixed in any order. For example, isobutanol is You can add a mixture of gasoline and suitable oxygenates to a mixture that includes it. As another example, one or more suitable oxygenates and isobutanol can be added in several different locations or in multiple stages. For other examples, the isobutanol can be added with the appropriate oxygenates, added before the suitable oxygenates or mixed with the suitable oxygenates before being added to a gasoline mixture reserve. In a preferred embodiment, isobutanol is added to the oxygenated gasoline. In another preferred embodiment, one or more suitable oxygenates and isobutanol are mixed in a gasoline mixture pool contemporaneously.

In any embodiment, more than one suitable oxygenate can be used instead of a single suitable oxygenate. Suitable oxygenates and isobutanol can be added at any point within the distribution chain. For example, a stock of gasoline mixture can be transported to a terminal and then the suitable oxygenates and isobutanol can be mixed with the gasoline mixture stock, individually or together, in the terminal. As another example, a stock of gasoline mixture, one or more suitable oxygenates and isobutanol can be combined in a refinery. Other components or additives can be added at any point in the distribution chain.

In another embodiment, a method is provided to reduce the PVR of an oxygenated gasoline. The method can be practiced in a refinery, terminal, place of retail sale, or any other suitable point in the distribution chain. Preferably, the method is practiced in a terminal designed to mix ethanol or some other oxygenate with a stock of gasoline mixture or in a terminal that can be adapted to accommodate this mixture.

According to another embodiment, a gas mixture pool is mixed with either ethanol, another suitable oxygenate, or a combination of suitable oxygenates, and isobutanol, to produce an oxygenated gasoline fuel having a lower PVR than oxygenated gasoline without Isobutanol.

The PVR value of the isobutanol mixture is lower than the PVR value of the remaining mixture. Preferably, the PVR of the isobutanol mixture is at most about 50% of the PVR of the remaining mixture. Optionally, the PVR of the isobutanol mixture is less than about 34.5 kPa (5.0 psi), more preferably less than about 20.7 kPa (3.0 psi), more preferably less than about 0 kPa (0.0 psi).

Gasoline regulations set limits on various fuel properties, which typically include an upper limit on PVR. These PVR limits may vary with the country, region and season. These PVR limits place a restriction on the product of the refinery, which can be used as gasoline. Usually, oxygenates, when mixed in a gas mixture reserve will raise the PVR of the resulting mixture. Gasoline blending reserves for mixtures of oxygenates, typically, have a PVR sufficiently below any applicable upper limit to account for the anticipated effect of oxygenate. This also restricts the refinery product, which can be used for gasoline because fewer high volatility fuel components can be used for gasoline blending fuels. These restrictions of the PVR can limit the amount of gasoline available for consumption.

In another embodiment, a method is provided to reduce the restrictions of the PVR in the refinery for the production of gasoline mixture reserve for the mixture of oxygenates. The restriction of PVR in a refinery decreases because oxygenated gasoline that complies with the limits of the regulatory PVR, can be produced using gasoline mixture reserve, which could not otherwise be usable to produce oxygenated gasoline in accordance with the PVR. Another embodiment provides a method to reduce the PVR of an oxygenated gasoline such that some oxygenated gasoline which could not otherwise satisfy the regulatory PVR limits, could also be mixed to meet these regulatory PVR limits.

In another modality, an oxygenated gasoline is produced by mixing a reserve of selected gasoline mixture, a selected oxygenate and isobutanol to form an oxygenated gasoline. Isobutanol reduces the PVR value of oxygenated gasoline. For a particular suitable oxygenate and particular gasoline blending reserve, the use of isobutanol may allow the use of a gasoline blending stock with a higher PVR value that, typically, could be used to produce an oxygenated gasoline that satisfies the regulations of PVR applicable.

For a given maximum PVR value, a gasoline mixture reserve and an adequate oxygenate are selected such that, although the PVR value of the gasoline mixture reserve mixture and the suitable oxygenate, may exceed the PVR value maximum, the PVR value of the oxygenated gasoline mixture containing the gasoline mixture reserve, the appropriate oxygenate and isobutanol is less than or equal to the maximum PVR value.

Without limiting the scope, the following examples illustrate various embodiments of the invention. The following specific example is set forth in the context of an unleaded gasoline fuel that meets the performance characteristics of ASTM D4814, but those skilled in the art will note that the invention is not limited to such a fuel and can be used with any reserve of gasoline or fuel mixture consistent with the description herein.

EXAMPLE A reserve of regular unleaded gasoline mixture that satisfies the performance characteristics of ASTM D4814-01a was mixed with 10% by volume of a suitable oxygenate. Ethanol was used as the appropriate oxygenate. The PVR of the resulting oxygenated gasoline was measured to be 66.8 kPa (9.69 psi) when measured in accordance with ASTM D5191. Isobutanol (14 volume%) was mixed with the oxygenated gasoline and the PVR of the resulting mixture was 59.6 kPa (8.64 psi) when measured according to ASTM D5191. The PVR value of the mixture calculated for the 14% by volume mixture was 15.1 kPa (2.19 psi).

The previous example shows how isobutanol can reduce the PVR of an oxygenated gasoline. In regions that have a maximum PVR limit, refineries typically produce gasoline mixture reserve significantly below that limit in anticipation of an increase in PVR from mixing oxygenates. Because isobutanol can be used to reduce the PVR of an oxygenated gasoline, refineries can use gasoline blending reserve to produce oxygenated gasoline that meets applicable PVR limits that gasoline blending reserves could not otherwise. be usable to produce oxygenated gasoline.

It is noted that in relation to this date, the best method known by the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims (37)

CLAIMS Having described the invention as above, the content of the following claims is claimed as property:

1. A gasoline composition characterized because it comprises: (a) a gasoline mixture reserve; (fc >) a suitable oxygenate; Y (c) isobutanol in an amount effective to reduce the PVR of oxygenated gasoline without isobutanol.

2. The gasoline composition according to claim 1, characterized in that the isobutanol has a PVR mixture value of less than about 34.5 kPa (5.0 psi).

3. The gasoline composition according to claim 2, characterized in that the isobutanol has a PVR mixture value less than about 0 kPa (0.0 psi).

4. The gasoline composition according to claim 1 or 2, characterized in that the value of the PVR of a mixture of the gasoline stock and the suitable oxygenate is at least about 47.6 kPa (6.9 psi).

5. The composition of gasoline in accordance with Claim 1, characterized in that the suitable oxygenate is an alcohol.

6. The gasoline composition according to claim 5, characterized in that the suitable oxygenate is ethanol.

7. The gasoline composition according to claim 6, characterized in that the ethanol is present in at least about 1% by volume.

The gasoline composition according to claim 7, characterized in that the isobutanol is present in at least 20% by volume.

9. The gasoline composition according to claim 8, characterized in that the ethanol is present in a maximum 20% by volume and the isobutanol is present from about 1% by volume to about 20% by volume.

10. The gasoline composition according to claim 1, characterized in that a mixture of the gasoline mixture reserve and the suitable oxygenate has a normalized relative absorbance greater than about 0.05.

11. The gasoline composition according to claim 10, characterized in that a mixture of the mixture reserve of gasoline, suitable oxygenate and isobutanol has a lower normalized relative absorbance that approximately 0.045.

12. The gasoline composition according to claim 11, characterized in that the isobutanol exhibits a PVR mixture value of less than about 34.5 kPa (5.0 psi).

13. The gasoline composition according to claim 11 or 12, characterized in that the value of the PVR of a mixture of the gasoline mixture reserve and the suitable oxygenate is at least about 6.9.

14. The gasoline composition according to claim 10, characterized in that the suitable oxygenate is ethanol.

15. A method for reducing the PVR of an oxygenated gasoline, characterized in that it comprises a stock of gasoline mixture, a suitable oxygenate and isobutanol in an amount effective to reduce the PVR.

16. The method in accordance with the claim 15, characterized in that the isobutanol has a PVR blend value of less than about 34.5 kPa (5.0 psi).

17. The method in accordance with the claim 16, characterized in that isobutanol has a PVR mixture value less than about 0 kPa (0.0 psi).

18. The method in accordance with the claim 15 or 17, characterized in that the value of the PVR of a mixture of the fuel mixture reserve and the oxygenate suitable is at least approximately 47.6 kPa (6.9 psi).

19. The method according to claim 15, characterized in that the suitable oxygenate is ethanol.

20. The method according to claim 19, characterized in that the ethanol is present in 20% by volume at most and the isobutanol is present from about 1% by volume to about 20% by volume in the resulting composition.

21. The method according to claim 15, characterized in that at least one suitable oxygenate or isobutanol is mixed in a terminal.

22. The method according to claim 15, characterized in that the suitable oxygenate and isobutanol are mixed with the gasoline mixture reserve contemporaneously.

23. The method according to claim 15, characterized in that a mixture of the gasoline mixture reserve and the suitable oxygenate has a normalized relative absorbance greater than about 0.05.

24. The method in accordance with the claim 23, characterized in that the mixture comprising the isobutanol, the gasoline mixture reserve and the suitable oxygenate has a normalized relative absorbance of less than about 0.045.

25. A method to reduce the restriction of the RRP in a reserve of gasoline mixture in the production of oxygenated gasolines having a predetermined maximum PVR limit, characterized in that it comprises mixing a stock of gasoline mixture, a suitable oxygenate and isobutanol in an effective amount to reduce the PVR, wherein a Mixture of the gasoline mixture reserve and the appropriate oxygenate has a PVR value greater than the predetermined maximum PVR limit and a mixture of the gasoline mixture reserve, the appropriate oxygenate and the isobutanol has a PVR value less or equal to the default maximum PVR limit.

26. The method according to claim 25, characterized in that the suitable oxygenate and isobutanol are mixed with the gasoline mixture reserve contemporaneously.

27. The method according to claim 25, characterized in that the isobutanol is mixed with the gasoline mixture stock before the suitable oxygenate is mixed with the gasoline mixture stock.

28. The method in accordance with the claim 25, characterized in that at least one of the suitable oxygenate or isobutanol is mixed with the stock of gasoline mixture in a terminal.

29. The method according to claim 25, characterized in that the suitable oxygenate is ethanol.

30. The method according to claim 29, characterized in that the ethanol is present in at least 1% by volume of the resulting composition.

31. The method according to claim 30, characterized in that isobutanol is present at less than about 20% by volume in the resulting composition.

32. The method according to claim 31, characterized in that the ethanol is present in from about 1% by volume to about 20% by volume and the isobutanol is present in from about 1% by volume to about 20% by volume in the resulting composition .

33. The method according to claim 25, characterized in that the oxygenated gasoline has a normalized relative absorbance greater than about 0.05.

34. The method in accordance with the claim 33, characterized in that the mixture comprising isobutanol and oxygenated gasoline has a normalized relative absorbance of less than about 0.045.

35. The method in accordance with the claim 34, characterized in that the suitable oxygenate is present in more than about 1% by volume and the isobutanol is present in less than about 20% by volume in the resulting composition.

36. The gasoline composition according to claim 25, characterized in that the isobutanol exhibits a PVR mixture value of less than about 34.5 kPa (5.0 psi).

37. The gasoline composition according to claim 36, characterized in that isobutanol exhibits a PVR mixture value of less than about 0 kPa (0.0 psi).