GASOLINE-OXYGENATE BLEND

Abstract: The invention provides a gasoline-oxygenate blend, suitable for use in an automotive spark-ignition engine, having the following properties: (a) Dry vapour pressure equivalent (DVPE) less than 7.4 PSI (51 x 10<3> Pa), and (b) an alcohol content greater than 5.0 volume percent; and a process for preparing such a blend which comprises blending at least two hydrocarbon streams and at least one oxygenate.

Description: GASOLINE-OXYGENATE BLEND Field of Invention This invention relates to gasoline-oxygenate blends containing at least one alcohol and processes for preparing the same . Background of the Invention Gasolines generally comprise mixtures of hydrocarbons boiling at atmospheric pressure in a comparatively narrow temperature range, e.g., 77°F (25°C) to 437°F (225°C) . Gasolines typically contain mixtures of aromatics, olefins, and paraffins, although some gasolines (gasoline oxygenate blends) may additionally contain oxygenates such as alcohols (e.g. ethanol) or other oxygenates (e.g. methyl t-butyl ether (" TBE")). Gasolines (including gasoline-oxygenate blends) may also contain various additives, such as detergents, anti-icing agents, demulsifiers, corrosion inhibitors, dyes, deposit modifiers, and octane enhancers. The presence of oxygen in the fuel tends to raise the effective air-to-fuel ratio for combustion and fuel oxygen may effect catalyst efficiency. While the oxygen in ethanol can raise this air-to-fuel ratio which may increase combustion temperature, the lower temperature of combustion for ethanol mitigates this effect. The oxygen in ethanol also reduces carbon monoxide ("CO") and volatile organic compound ( "VOC" ) emissions during high-emissions conditions in new vehicles and during all conditions for vehicles that do not have operational oxygen sensors or catalysts . The passage of the US Clean Air Act ("CAA") Amendments of 1990 has impacted all major transportation fuels in the United States and stimulated research into using alternative motor fuels that include oxygenates. In order to comply with the CAA, gasoline marketers admixed oxygenates into gasoline, but also changed the hydrocarbon composition by altering the content of benzene, total aromatics, butane, total olefins, and similar components. These considerations affect the reactivity of new gasolines and translate into the performance characteristics of admixed oxygenates, i.e, distillation, volatility, azeotropic behaviour, oxidation stability, solubility, octane values, vapour pressure, and other gasoline characteristics known to those skilled in the art . Research regarding oxygenated fuel substitutes and components has focused on aliphatic alcohols including, but not limited to, methanol, ethanol, isopropanol, t- butanol, and ethers such as TBE, ethyl t-butyl ether ("ETBE"), and t-amyl methyl ether ("TAME"). Most research has focused on using MTBE in gasoline formulation. Generally, oxygenate gasoline components have been blended into gasoline separately. However, there have been mixtures of such components disclosed, such as blends of gasoline containing components other than ethers, such as alcohols. Historically, gasoline vapour pressures have typically been in the range from 9 to 15 pounds per square inch ("PSI") of pressure (62 to 103.4 kPa) . Recent US evaporative emission regulations have forced reduction of gasoline vapour pressures. Ether components provide advantageous vapour pressure blending characteristics for these gasolines. In the late 1990s, the CAA caused refiners to reformulate gasoline to achieve vapour pressures in the range of 7.5 to 8.5 PSI (51.7 to 58.6 kPa) . This is because the CAA is trying to reduce vehicle emissions that constitute air toxins and participate in the formulation of air pollution ("smog"), for example, CO, NOx, and VOCs . These lower vapour pressure requirements provided motivation for the use of MTBE. It has been used in "premium" gasoline since 1979 as a high-octane additive to function as an oxygenate. In fact, MTBE has replaced lead and other highly contaminating additives such as benzene, toluene, ethylbenzene and xylenes ( "BTEX" ) . MTBE is an ether-having relatively low odour and taste thresholds compared to other organic compounds. MTBE's odour threshold in water is between about 45 and about 95 parts per billion ( "ppb" ) . Its taste threshold in water is about 134 ppb. As a result, MTBE can be detected if present in drinking water through odour and taste at relatively low concentrations. Ultimately, MTBE may be encountered through drinking contaminated water, use of the water in cooking, and inhalation during bathing. In USA, vast amounts of MTBE-containing gasoline are stored in underground storage tanks ("UST"), which have been known to leak. Seepage of MTBE from leaky tanks into groundwater and spillage of MTBE during tank filling operations and transfer operations at distribution terminals have led to considerable contamination of groundwater near these tanks. Because MTBE is highly soluble in water - about 43,000 parts per million ("PPM") - MTBE may be found as plumes in groundwater near service stations, related storage facilities, and filling terminals throughout USA. Use of MTBE is now perceived as undesirable. To this end, ethanol has been used as an alternative to MTBE in gasoline-oxygenate blends wherein the vapour pressure and emission requirements were less restrictive. Ethanol has some properties that are different than MTBE. However, ethanol blends have nearly twice the fuel -oxygen content of the MTBE blends. Furthermore, gasoline- ethanol blends exhibit as much as 1 PSI (6.9 kPa) higher Reid Vapour Pressure ("RVP") volatility unless adjustment of the base clear-gasolines is made to accommodate this volatility. With mounting pressures against the use of ethers such as MTBE, ethanol continues to find increasing application in low-RVP gasolines. Whilst ethanol poses no threat to surface water and ground water, in California more than 10,000 wells have been contaminated by MTBE and its pungent odour renders water undrinkable. In California elimination of MTBE use is required by the end of 2002. Accordingly, a need exists to reduce or replace MTBE additives in gasoline whilst retaining acceptable performance characteristics. Summary of the Invention According to the present invention there is provided a gasoline-oxygenate blend, suitable for use in an automotive spark- ignition engine, having the following properties :- (a) a Dry Vapour Pressure Equivalent (DVPE) less than 7.4 PSI (51 x 10 3 Pa) , and (b) an alcohol content greater than 5 volume percent. In use, the gasoline-oxygenate blend may contain, in addition to hydrocarbon and alcohol fuel components, one or more performance additives, such as detergents, anti- icing agents, demulsifiers, corrosion inhibitors, dyes, deposit modifiers, etc. Gasoline-oxygenate blends may conveniently be prepared in accordance with the invention by a process for preparing a gasoline-oxygenate blend which comprises blending at least two hydrocarbon streams and at least one oxygenate to produce a gasoline-oxygenate blend having the following properties :- (a) a Dry Vapour Pressure Equivalent (DVPE) less than 7.4 PSI (51 x 10 3 Pa) , and (b) an alcohol content greater than 5.0 volume percent. In a preferred gasoline-oxygenate blend of the invention, the DVPE is at least 6.5 PSI (44.8 x 10 3 Pa) . The alcohol content is preferably up to 10 volume percent . Preferred gasoline-oxygenate blends in accordance with the present invention may have one or more of the following characteristics : - (i) the oxygenate comprises ethanol, (ii) the blend is substantially free of methyl t-butyl ether (MTBE) , (iii) the 10% distillation point (T10) of the blend is at least 130°F (54.4°C), (iv) the 10% distillation (T10) point of the blend is not greater than 145°F (62.8°C), (v) the 50% distillation point (T50) of the blend is at least 190°F (87.7°C), (vi) the 50% distillation point (T50) of the blend is not greater than 230°F (110°C) , (vii) the 90% distillation point (T90) of the blend is at least 270°F (132.2°C), (viii) the 90% distillation point (T90) of the blend is not greater than 355°F (179.5°C), (ix) T90 is not greater than 350°F (176.5°C), (x) the distillation end point (EP) of the blend is at least 360°F (182.3°F) , (xi) the distillation end point (EP) of the blend is not greater than 435°F (223.9°C), (xii) EP is not greater than 410°F (210°C) , (xiii) the 200°F (93.3°C) distillation fraction (E200) is in the range 30 to 55, preferably 35 to 55, volume percent , (xiv) the 300°F (148.9°C) distillation fraction (E300) is in the range 70 to 95 volume percent, (xv) DVPE is in the range 6.5 PSI (44.8 x 10 3 Pa) to 7.4 PSI (51 x 10 3 Pa) , (xvi) DVPE is in the range 6.5 PSI (44.8 x 10 3 Pa) to 7.05 PSI (48.6 x 10 3 Pa) , (xvii) the anti-knock index ((R+M)/2) is in the range 87 to 95, (xviii) the anti-knock index ((R+M)/2) is at least 89, (xix) the alcohol content is in the range 5 to 10 volume percent, (xx) the alcohol content is in the range 5.4 to 10 volume percent, (xxi) the oxygen content of the gasoline-oxygenate blend is in the range 1.95 to 3.7 weight percent. (xxii) the DVPE is less than 7.1 PSI (49 x 10 3 Pa) and the alcohol content is greater than 5.8 volume percent , (xxiii) the DVPE is less than 7 PSI (48.3 x 10 3 Pa) and the alcohol content is greater than 5 volume percent, (xxiv) the DVPE is less than 7.2 PSI (49.6 x 10 3 Pa) and the alcohol content is greater than 9.6 volume percent . The present invention envisages as preferred aspects of the invention any combination of two or more of characteristics (i) to (xxi) above, and any combination of characteristic (xxii) , (xxiii) or (xxiv) with any one or more of characteristics (i) to (xxi) . According to a preferred aspect of the present invention there is provided a gasoline-oxygenate blend, suitable for use in an automotive spark-ignition engine, having the following properties :- (a) a Dry Vapour Pressure Equivalent (DVPE) less than 7.2 PSI (49.6xl0 3 Pa), and (b) an alcohol content greater than 5.0 volume percent, provided that when the alcohol content does not exceed 9.6 volume percent, the DVPE is less than 7.1 PSI (49xl0 3 Pa), and when the alcohol content does not exceed 5.8 volume percent, the DVPE is less than 7 PSI (48.3xl0 3 Pa) . The present invention facilitates the provision of gasoline-oxygenate blends that produce a relatively low amount of gaseous pollutants with the reduction or elimination of MTBE as a fuel additive. The invention provides methods for producing gasoline-oxygenate blends having such desirable properties as overall emission performance such as: the reduction of Toxics, NOx, and VOCs; oxygen content; and requisite volatility characteristics including vapour pressure, and the 200°F (93.3°C) and 300°F (148.9°C) distillation fractions as discussed herein. This composition and its method of production offer a solution by including at least one alcohol while combating pollution, particularly in congested cities and the like, when large volumes of automotive fuel of the invention are combusted in a great number of automobiles in a relatively small geographical area. The present invention, in its broadest aspect, is founded on the discovery that when gasolines are produced, for example, by blending a plurality of hydrocarbon-containing streams together so as to produce a gasoline-oxygenate blend, controlling certain chemical and/or physical properties of the gasoline-oxygenate blend, controlling certain chemical and/or physical properties of the gasoline-oxygenate blend can improve the reduction of emissions of one or more pollutants. For example, a first hydrocarbon-containing stream boiling in the gasoline range can be blended with a different hydrocarbon stream at rates adjusted so as to reduce the introduction of MTBE while improving the vapour pressure and the 50% Distillation Point. The greater decrease of the introduction of MTBE while maintaining the other properties of the blend as set forth above, the greater the resulting benefit in reducing emissions while fulfilling all regulatory requirements . In one preferred embodiment, the present invention provides a gasoline-oxygenate blend composition and a method of producing the same containing at least one alcohol, most preferably ethanol, exhibiting greater than 5 volume percent and up to about nine (9) volume percent (%) or more of the composition and having a vapour pressure less than about 7.1 PSI (49 kPa) which meets all ASTM Specifications and Federal/State Regulatory Requirements. In a preferred embodiment, the volume of this alcohol may be reduced to about seven (7) volume percent, or even about five (5) volume percent in a most preferred embodiment. Though this preferred embodiment utilizes ethanol, it is envisioned that virtually any alcohol may reduce or replace the introduction of MTBE in the blending process and the compositions formed therefrom. In a preferred embodiment, the gasoline-oxygenate blend has a vapour pressure less than about 7.1 PSI (49 kPa) and an alcohol content greater than about 5.8 volume percent. In another embodiment, this gasoline-oxygenate blend will have a 50% distillation point less than about 195°C (90.6°C), a 10% distillation point less than about 126°F (52.2°C), an oxygen weight percent that is greater than 1.8 weight percent, an anti -knock index greater than or equal to about 89, and/or the capability to reduce toxic air pollutants emissions by more than about 21.5% as calculated under the Complex Emissions Model ("Complex Model") under 40 C.F.R. § 80.45 (1999), more preferably more than about 30% for the appropriate location, season, and year. Though the present invention may substituted virtually any alcohol for MTBE, the inclusion of ethanol to reduce or replace MTBE is preferable. In another embodiment, the gasoline-oxygenate blend has a vapour pressure less than about 7.2 PSI (49.6 kPa) and an alcohol content greater than about 9.6 volume percent. This embodiment may also have a 50% distillation point less than about 178°F (97.8°C), a 10% distillation point less than about 123°F (50.6°C), an oxygen weight percent that is greater than 1.8 weight percent, an anti -knock index greater than about 89, and/or the capacity to reduce toxic air pollutants emissions by more than about 21.5%. In a further embodiment, the gasoline-oxygenate blend has a vapour pressure less than about 7 PSI (48.3 kPa) and an alcohol content greater than about 5.0 volume percent. This embodiment may also have a 50% distillation point less than about 250°F (121.1°C) and/or a 10% distillation point less than about 158°F (70°C) . With regard to the forming of these gasoline- oxygenate blends, this invention also includes the process for preparing a gasoline-oxygenate wherein the resulting blend has a vapour pressure less than about 7.1 PSI (49 kPa) and an alcohol content greater than about 5.8 volume percent while reducing or eliminating the inclusion of MTBE. The gasoline-oxygenate blends may be formed by blending at least two hydrocarbon streams to produce a gasoline-oxygenate blend suitable for combustion in an automotive engine wherein the resulting blend has a vapour pressure less than about 7 PSI (48.3 kPa) and an alcohol content greater than about 5.0 volume percent. This process can produce a blend that reduces toxic air pollutant emissions by more than about 21.5%, more preferably about 30%. Brief Description of the Drawings The present invention will be further understood from the following detailed description of preferred embodiment thereof, which is made by way of example only, with reference to the accompanying drawing, in which: - Figure 1 represents a block diagram of an oil refinery. Brief Description of Preferred Embodiments Before discussing the preferred embodiments, some of the rules and regulations that preceded this invention will be discussed. Those skilled in the art will recognize that changes, amendments, or revisions to the rules, regulations, requirements, laws, and standards are considered to be within the scope of the invention and the benefits of the invention as described and claimed herein are not dependent on these factors. The following terms, extracted from the CAA, are helpful in understanding the following tables. Antiknock index is the arithmetic average of the Research octane number ( "RON" ) and Motor octane number ( "MON" ) , that is (R+M)/2. RON is determined by a method that measures fuel anti -knock level in a single-cylinder engine under mild operating conditions; namely, at a moderate inlet mixture temperature and a low engine speed. RON tends to indicate fuel anti -knock performance in engines wide-open throttle and low-to-medium engine speeds. MON is determined by a method that measures fuel anti-knock level in a single-cylinder engine under more severe operating conditions than those employed in the Research method; namely, at a higher inlet mixture temperature and at a higher engine speed. It indicates fuel anti-knock performance in engines operating at wide- open throttle and high engine speeds. Also, MON tends to indicate fuel anti -knock performance under part-throttle, road-load conditions. Additionally, Reid Vapour Pressure ("RVP") refers to the absolute vapour pressure of volatile crude oil and volatile non-viscous petroleum liquids, except liquefied petroleum gases, as determined by the Standard Test method for Vapour Pressure of Petroleum Products (Reid Method), ASTMD D 323. The vapour pressure or Dry Vapour Pressure Equivalents ("DVPE") can be determined following the Standard Test Method for Vapour Pressure of Gasoline and Gasoline-Oxygenate Blends (Dry Method) ASTM D 4953, the Standard Test Method for Vapour Pressure of Petroleum Products (Automatic Method) ASTM D 5190, the Standard Test Method for Vapour Pressure of Petroleum Products (Mini Method) ASTM D 5191, and the Standard Test Method for Vapour Pressure of Petroleum Products (Mini Method- Atmospheric) ASTM D 5482. With the terms in mind, fuels have some basic properties that are shown in Table 1 below. TABLE 1: PROPERTIES OF FUELS These fuels must meet several requirements. Some of these requirements are related to the Vapour Pressure and Distillation Class. The Standard Specification for Automotive Spark- Ignition Engine Fuel, ASTM D 4814, sets out vapour pressure and distillation class requirements for each vapour pressure and distillation class. TABLE 2: VAPOUR PRESSURE AND DISTILLATION CLASS REQUIREMENTS To model this, the CAA lays out standards and appropriate Emission Models to calculate performance of gasoline blends. The following properties of the baseline fuels must be observed when blending gasolines. In addition to the properties discussed the following terms are included in the following table from the Complex Model of 40 C.F.R. §80.45 (1999). E200 is the fraction of the target fuel that evaporates (the distillation fraction) at 200°F (93.3°C) in terms of volume percent. E300 is the fraction of the target fuel that evaporates (the distillation fraction) at 300°F (148.9°C) in terms of volume percent. TABLE 3 : COMPLEX EMISSIONS MODEL FOR THE BASELINE FUEL PROPERTIES Not only must these fuel properties be observed, the fuels must not exceed the following baseline exhaust emissions. The abbreviations for polycyclic organic matter ("POM") and Nitric Oxide ( "NOx" ) are used in the following table that lists the baseline exhaust emissions for Phase I (the Years 1995-1999) and Phase II (the Year 2000 and beyond) . TABLE 4 BASELINE EXHAUST EMISSIONS Ultimately, these properties and baselines are promulgated to insure compliance with the Total Baseline for VOCs, NOx, and Toxic Emissions in both Phases I and II, in Region 1, the Southern States of USA and Region 2, the Northern States of USA as shown in the following table. TABLE 5: TOTAL BASELINE VOC, NOX AND TOXICS EMISSIONS o With these requirements, models, and standards in place, the following outlines how to meet these standards while reducing or eliminating the introduction of MTBE. In fact, the following demonstrates how to reduce Toxic Emissions ( "ToxR" ) by about 30% such that the Phase II Summer Emissions are from about 53.5 mg/mile (33.4 mg/km) to about 37.5 mg/mile (23.4 mg/km) using the calculations shown in 40 C.F.R. § 80.45 (1999) . To blend at least one gasoline-oxygenate blend that complies with these requirements, a refinery produced several blends that were tested for compliance with these requirements. With reference to Figure 1, a block flow diagram of one embodiment of a refinery is shown. As with most refineries, a number of different units have been integrated into a processing sequence. Those skilled in the art will appreciate that virtually combinations and permutations of the units shown in different configurations may be arranged or configured to effectuate the goal of creating refinery products while reducing or eliminating the introduction of MTBE. The block diagram shows units for separation, conversion, and blending. As with most oil refineries, the representative refinery depicted in Figure 1 separates crude oil into its various fractions, converts these fractions into distinct components, and finally blends those components into finished products. Separation of petroleum crude into its various fractions takes place in a crude distillation tower 1, which is an atmospheric and vacuum distillation tower. The resulting hot vapours rise and cool at various levels within the distillation tower 1, condensing on horizontal trays. The trays at the top of the unit collect the lighter petroleum fractions, while the heavier components settle on the lower trays. Prior to introduction, crude oil may be first heated in a furnace. The trays on the upper levels collect the lighter petroleum fractions such as naphtha (straight-run gasoline) and kerosene. Middle trays collect components such as light heating oil and diesel fuel. Heavy fuel oils, asphalt, and pitch fractions settle on lower trays. Some of the components may be collected as conversion feeds in conversion feed unit 8. Those vapours that do not condense in the distillation tower 1 are removed from the top as light gases. At each condensation level, the separated fractions are removed from the trays through pipes known as side draws. The heaviest liquid residue is drawn off at the bottom of the tower as reduced crude through line 28. This may be sent to a coker unit 12. Moreover, some of the lines from the distillation tower 1 may run to a distillation fuels collection unit 13. Each of these streams may undergo some form of conversion, isomerization, or other change. The most common conversion processes are cracking, combining, and rearranging. Figure 1 shows several units capable of this process, including, but not limited to a fluid catalytic cracking unit 10. The fluid catalytic cracking unit 10 converts gas oil from the crude distillation tower 1 into gasoline blending stocks and fuel oils. It does this through a conversion process known as cracking. Catalytic cracking breaks down larger, heavier, and more complex hydrocarbon molecules into simpler and lighter molecules by applying heat, pressure, and a catalyst. Catalytic cracking may further occur in the hydrolytic cracker 5. Additionally, this flow diagram shows the process of alkylation and polymerization being included in this refinery. These processes link smaller, lighter molecules to form larger, heavier ones. Alkylation and polymerization units such as the alkylation unit 7 and the polymerization/dimerization unit 6 produce high- octane gasoline blending stock from cracked gases. Reformers and isomerization units such as isomerization and/or saturated hydrodesulfuration unit 2 and catalytic reformer 4 offer these benefits to the process shown. Typically, a reformer converts naphthas or low-octane gasoline fractions in the presence of heat, pressure, and at least one catalyst into higher octane stocks suitable for blending into gasoline. Isomerization units such as isomerization and/or saturated hydrodesulfuration unit 2 rearrange the molecules from straigh-chain, low-octane hydrocarbons to branched-chain, high-octane hydrocarbons known as isomers. The resulting isomerate is a preferred gasoline blending stock. Moreover, some petroleum fractions have sulfur, nitrogen, heavy metals, and other impurities in them. These contaminants may have detrimental effects on equipment, catalysts, and the quality of the finished product. Hydrotreating is a conversion process that removes many of these impurities by mixing untreated fractions with hydrogen in the presence of a catalyst. The naphtha hydrodesulfuration unit 3, the catalytic feed hydrotreater 9, and the catalytic gasoline hydrotreater 11 are examples of units that may be included in a refinery to remove these impurities. These units are typically connected by a plurality of pipes or similar transfer conduits known to those skilled in the art to offer continuous feeds. In the preferred embodiment depicted herein, line 20 feeds crude oil into distillation tower 1. Numerous lines lead from distillation tower 1. Lines 21, 22, 23, 24, 25, 26, 27, and 28 lead from the distillation tower 1. Line 21 runs to an isomerization and/or saturated hydrodesulfuration unit 2. Line 21 contains straight run light gasoline. Line 22 runs to a naphtha hydrodesulfuration unit 3. Line 22 contains straight run naphthalene. Lines 23 and 24 run to a distillation fuels collection unit 13. Line 23 contains straight run kerosene. Line 24 contains straight run, light gas oil. Lines 25, 26, and 27 run to conversion feeds unit 8. Line 25 contains straight heavy gas oil. Line 26 contains straight run, light vacuum gas oil. Line 27 contains straight run, heavy vacuum gas oil. Line 28 runs to a coker 12. Line 28 contains vacuum residuum. The oils collected in the collection feed unit 8 feed into a hydrolytic cracker 5 and a catalytic feed hydrotreater 9 via lines 29 and 30, respectively. Each straight run product may undergo further processing by various other refinery units before becoming marketable end products. As shown, lines 31, 32, 33, 34, and 35 lead from the coker 12. Line 31 runs to the hydrolytic cracker 5 and contains coker heavy gas oil. Line 32 runs to the distillation fuels collection unit 13 and contains coker light gas oil. Line 33 runs to the catalytic feed hydrotreater 9 and contains coker heavy gas oil . Line 34 runs to the naphtha hydrodesulfuration unit 3 and contains coker naphtha. Line 35 runs to the isomerization and/or hydrodesulfuration unit 2 and contains coker naphtha. Lines 36 and 37 run from the hydrodesulfuration unit 3 to the catalytic reformer 4. Lines 38 to 41 run from the hydrolytic cracker 5. Line 38 runs to the isomerization and/or saturated hydrodesulfuration unit 2 and contains hydrolytically cracked light gasoline. Line 39 runs to the catalytic reformer 4 and contains hydrolytically cracked naphtha. Line 40 runs to the distillation fuels collection unit 13 and contains hydrolytically cracked gas and/or oil. Line 41 runs to the alkylation unit 7 and contains hydrocarbons such as butane . Line 42 runs from the catalytic feed hydrocracker 9 to the fluid catalytic cracking unit 10. From the fluid catalytic cracking unit 10, line 43 runs to at least one of the polymerization/dimerization unit 6 and/or the alkylation unit 7 and contains at least one hydrocarbon such as propane. Line 44 also runs from the fluid catalytic cracking unit 10 to polymerization/dimerization unit 6 and contains a hydrocarbon such as butane. Lines 45 and 46 run from the fluid catalytic cracking unit 10 to the catalytic gasoline hydrotreater 11 and contain fluid catalytic cracked light naphtha and fluid catalytic cracked heavy naphtha, respectively. Line 47 runs from the fluid catalytic cracking unit 10 to the distillation fuels collection unit 13 and contains fluid catalytic cracked light gas oil. Line 48 leads from the fluid catalytic cracking unit 10 to the coker unit 12 and contains fluid catalytic cracked heavy cycle oil and slurry. A third significant part of the refinery process is blending. Final products may be obtained by mixing two or more blending components as well as additives to improve product quality. To this end, most grades of motor gasoline are blends of various fractions including straight-run naphthas, reformate, cracked gasoline, isomerate, and poly-gasoline. Other blended products include fuel oils, diesel fuels, jet fuels, lubricating oils, and asphalts. This blending process is an important aspect of the present invention. The gasoline compositions and the blends utilized to obtain these compositions and properties are disclosed herein. Though this disclosure shows the benefits of the inclusion of at least some ethanol in the blending process, those skilled in the art will realize the process and compositions may utilize virtually any alcohol to reduce or eliminate the introduction of MTBE in the blending process. In Figure 1, produce lines 50. 51, 52, 53, 54, 55, and 56 are shown. Line 50 comes from the isomerization and/or saturated hydrodesulfuration unit 2 and contains straight run, hydrolytically cracked light gasoline and/or isomerate. Line 51 come form the catalytic reformer 4 and contains reformate. Line 52 will be discussed below. Line 53 comes from the polymerization/dimerization unit 6 and contains polymerized/dimerized gasoline. Line 54 comes from the alkylation unit 7 and contains alkylate. Lines 55 and 56 come from the catalytic gasoline hydrotreater 11 and contain catalytically hyrotreated gasoline light and heavy catlytically hydrotreated gasoline, respectively. Additionally, oxygenates may be introduced via oxygenate unit 14 in line 52. The oxygenates such as an alcohol may be introduced to the stream output of lines 50, 51, 53, 54, 55, and/or 56. In the most preferred embodiment, the introduction of ethanol occurs via line 52. It is important and advantageous to note that the only oxygenate needed in the preferred embodiment is ethanol. Other alcohols that may be used include but are not limited to methanol , propanol , iso-propanol , butanol, secondary butanol, tertiary-butanol , alcohols having about five carbon atoms, and similar alcohols. Oxygenate unit 14 is not necessarily located at the refinery. Oxygenates, such as ethanol, may be added to the finished gasoline downstream of the gasoline blending process. Accordingly, the present invention may benefit from the blending of the oxygenates at a remote located not physically located at the refinery. Using this refinery and blending process, the following blends have been produced. After showing the composition of the blends, the properties of these blends are discussed. Furthermore, the effect of including oxygenates in the blends will be shown. These compositions of the blends with oxgenates are shown. Finally, the properties of the blends, including oxygenates, will be shown and discussed. Prior to the introduction of the next table, the volume percentage of streams that were blended prior to the introduction of oxygenates, the following column heading meanings are needed. "C4" is used in the following tables to denote the inclusion of hydrocarbons such as butane . The "FFB" usually includes a stream of hydrocarbons wherein the number of carbon atoms in each molecule of the hydrocarbon is preferably in the range from 4 to 5. The FFB may preferably be a portion of stream 41, a separated product from hydrolytic cracker 5, combined with a portion of the straight-run gasoline from line 21. In a preferred embodiment, FFB is about 20% butane, about 65% isopentane, and remainder normal -pentane . In a preferred embodiment, the straight run gasoline is caustic treated to remove mercaptan sulfur and combined with other streams which are separated by using a fractionation column. "RAFF", raffiinate, refers to the paraffin portion of straight run naphtha and hydrolytically cracked light naphtha from the stream 36 after it has run through a catalytic reformer 4 and preferably a benzene extraction unit. Raffinate usually includes a stream of paraffinic hydrocarbons wherein the number of carbon atoms in each molecule of the hydrocarbon is preferably in the range from 5 to 7 in the light reformate product. "HOR" is used in the following tables to denote the inclusion of at least one high octane reformate, preferably a product in the line 51 from the catalytic reformer unit 4. "TOL" is the aromatic portion of stream 36 as described above, which no longer has a significant benzene content. In a preferred embodiment, TOL is essentially about 65-70 volume percent toluene, about 10- 15 volume percent mixed xylenes, and the remainder is paraffinic hydrocarbons wherein the number of carbon atoms in each molecule of the hydrocarbon is preferably at least 8. "LCC" is used in the following tables to denote the inclusion of at least one light catalytically cracked gasoline. Preferably, LCC is a combination of light catalytically cracked gasoline from stream 45 and light hydrolytically cracked gasoline from stream 38 after these products have been caustic treated to remove mercaptans . "HCC" is used in the following tables to denote the inclusion of at least one heavy fluid catalytically cracked gasoline such as the product in line 46 and light straight run gasoline 21 after these products have been caustic treated to remove mercaptans. "ALKY" is used in the following tables to denote the inclusion of at least one alkylate such as the product from the line 54 from the alkylation unit 7 in the preferred embodiment . "LSCC" denotes the heaviest portion of stream 46 - the heavy fluid catalytically cracked gasoline in line 56 after it has been hydrotreated to reduce the sulfur content. Those skilled in the art will recognize that the inclusion of any low-sulfur catalytically cracked gasoline, regardless of how provided, may be used in this fashion and that it is likely that this sream may have been hydrotreated to reduce the sulfur content to an acceptably low level . With these terms in mind, the following Tables 6-15 show blends that have been made. These tables have been divided into blends that were made in 1999 represented by Tables 6-10 and blends that have been made after 1999 in Tables 11-15. Adopting the terms "Phase I" (the Years 1995-1999) and "Phase II" (the Year 2000 and beyond) , the following tables provide examples that were blended under both Phase I and Phase II. Additionally, prior to the introduction of any oxygenates, each blend will be referred to as a "neat" blend. Once oxygenates have been introduced, each blend will be referred to as a gasoline-oxygenate blend. With these terms in mind, the following tables show the recipes and properties of these blends. Tables 6 and 11 show the neat blend recipes in Phase I and Phase II, respectively. Tables 7 and 12 show the neat blend properties in Phase I and Phase II, respectively. Tables 8 and 13 show the gasoline-oxygenate blend recipes in Phase I and Phase II, respectively. Tables 9 and 14 show the gasoline-oxygenate blend properties in Phase I and Phase II, respectively. Finally, Tables 10 and 15 show the additional gasoline-oxygenate blend properties in Phase I and Phase II, respectively. Of note, the percentage reduction of NOx, toxic pollutants, and VOCs shown in Table 10 and 15 were calculated using the Complex Model that was in effect during the appropriate Phase. For example, the percentage reductions shown in Table 10, entitled "Additional Phase I Gasoline-Oxygenate Blend Properties," show calculations based on the Complex Model Phase I as prescribed in 40 C.F.R. §80.45 (1999) . Accordingly, Table 15, entitled "Additional Phase II Gasoline- Oxygenate Blend Properties" shows the percentage reduction of NOx, toxic pollutants, and VOCs using the Complex Model Phase II as prescribed by Federal Regulations under 40 C.F.R. § 80.45 (1999). With respect to percentage reductions described herein, unless otherwise indicated, the Phase II Complex Model for determining the percentage reduction of NOx, toxic pollutants, and/or VOCs are to be calculated under the Phase II Complex Model as prescribed in 40 C.F.R. § 80.45 (1999) unless otherwise indicated. Returning to the following Table 6, entitled "Phase I Neat Blend Recipes, " the following neat blends were formulated. TABLE 6: PHASE I NEAT BLEND RECIPES TABLE 6: PHASE I NEAT BLEND RECIPES (cont'd) Uι Ul These neat blends were tested online using certified online analyzers calibrated to ASTM standards and methods. The following Table 7 includes neat blend properties wherein each blend, designated by a letter designation A-X, corresponds to the same letter designation A-X from Table 6. The Research Octane Number ("RON") and the Motor Octane Number ("MON") were collected using calibrated online analyzers using the testing procedures found in the Standard Test Method for Research and Motor Method Octane Ratings Using Online Analyzers, ASTM D 2885. The anti-knock index number or octane number ( " (R+M) /2" ) was established by averaging RON and MON. The DVPE was established by using an online testing method certified equivalent for the testing procedures found in The Standard Test Method for Vapour Pressure of Petroleum Products (Mini Method) , ASTM D 5191 and is expressed in PSI. The 10% distillation temperature, the 50% distillation temperature, the 90% distillation temperature, the end point distillation temperature ("T10", "T50", "T90", and "EP" respectively) and the 200°F (93.3°C) and the 300 °F (148.9°C) distillation fractions ("E200" and "E300", respectively) were collected using certified online procedures equivalent to the testing methods found in The Standard Specification for Automotive Spark-Ignition Engine Fuel, ASTMD D 4814. With these testing procedures in mind, the neat blends had the following properties prior to the introduction of oxygenates . TABLE 7 PHASE I NEAT BLEND PROPERTIES Uι Ul TABLE 7: PHASE I NEAT BLEND PROPERTIES (cont'd) Uι Oxygenates were introduced via an oxygenate unit 14 in a line 52. As mentioned previously, the inclusion of oxygenates does not have to occur on the premises of the refinery. With regard to these blends, the oxygenate was added to the finished gasoline downstream of the gasoline blending process. To each of these blends, oxygenates were introduced such that the oxygenates of the blend comprised less than or equal to about ten (10) volume percent. Each of the gasoline-oxygenate blends contained denatured ethanol meeting the U.S. Standard Specification for Denatured Fuel Ethanol for Blending with Gasolines for Use as Automotive Spark- Ignition Engine Fuel ASTM D 4806 as the oxygenate. The following Table 8, entitled "Phase I Gasoline- Oxygenate Blend Recipes," shows a series of blend recipes that resulted in the gasoline-oxygenate blends after the introduction of at least one oxygenate to the corresponding neat blends shown in Table 6-7. Of note, a significant amount of the blends A-X were used in the formulation of two gasoline-oxygenate blends. For example, neat blend A shown in Tables 6-7 was blended with ethanol to form a gasoline-oxygenate blend Al wherein the ethanol was 9.5 volume percent. Similarly, this same neat blend A was blended with ethanol to create the gasoline-oxygenated blend A2 wherein the ethanol content was 5.42 volume percent. Therefore, the gasoline-oxygenate blends Al and A2 represent variations in the introduction of oxygenates to neat blend A. The Phase I gasoline-oxygenate blend recipes shown in Table 8 are arranged such that the corresponding blend letter relates to the corresponding blend letter shown in Table 6-7. In the event that a plurality of gasoline- oxygenate Phase I blend recipes were made for each neat blend A-X, the corresponding gasoline-oxygenate Phase I blend recipes in Table 8 have been designated by the blend letter designation, for example A, followed by a numerical designation, for example 1, such that the gasoline-oxygenate property shown in Tables 9-10 correspond to the blend letter, and number designation, if applicable. Accordingly, Table 8, entitled "Phase I Gasoline-Oxygenate Blend Recipes," shows each gasoline- oxygenate blend recipe in terms of volume percent of the total blend after the introduction of oxygenates. TABLE 8: PHASE I GASOLINE-OXYGENATE BLEND RECIPES TABLE 8: PHASE I GASOLINE-OXYGENATE BLEND RECIPES (cont'd) TABLE 8: PHASE I GASOLINE-OXYGENATE BLEND RECIPES (cont'd) Each of the gasoline-oxygenate blends was tested offline using the appropriate laboratory ASTM procedure found in the U.S. Standard Test Method for Research Octane Number of Spark-Ignition Engine Fuel, ASTM D 2699, the U.S. Standard Test Method for Motor Octane Number of Spark-Ignition Engine Fuel, ASTM D 2700, the U.S. Standard Test Method for Vapour Pressure of Petroleum Products (Mini Method), ASTM D 5191, and the U.S. Standard Test Method for Distillation of Petroleum Products at Atmospheric Pressure, ASTM D 86. As before, each blend designation shown below corresponds to the gasoline-oxygenate blend recipe shown in Table 8. For example, gasoline-oxygenate blend Al in Table 9 corresponds to the blend recipe shown for gasoline-oxygenate blend designation Al in Table 8. Similarly, gasoline-oxygenate blend A2 below corresponds to the gasoline-oxygenate blend designation A2 in Table 8. With these designations in mind, the following gasoline-oxygenate blend properties were determined. TABLE 9 PHASE I GASOLINE-OXYGENATE PROPERTIES TABLE 9: PHASE I GASOLINE-OXYGENATE PROPERTIES (cont'd) TABLE 9: PHASE I GASOLINE-OXYGENATE PROPERTIES (cont'd) 4- Ul Additional properties of the Phase I gasoline- oxygenate blends were determined using offline testing. The Oxygen ( "Oxy" ) content was established by using the testing procedures found in The Standard Test Method for Determination of MTBE, ETBE, TAME, DIPE, tertiary-Amyl Alcohol and C^ to C4 Alcohols in Gasoline by Gas Chromatography, ASTM D 4815, and is expressed in weight percent. The Aromatics ( "Arom" ) content was established by using the testing procedures found in The Standard Test Method for Hydrocarbon Types in Liquid Petroleum Products by Fluorescent Indicator Adsorption, ASTM D 1319, and is expressed in volume percent. The Olefins ("Olef") content was established by using the testing procedures found in The Standard Test Method for Hydrocarbon Types in Liquid Petroleum Products by Fluorescent Indicator Adsorption, ASTM D 1319, and is expressed in volume percent. The Benzene ("Benz") content was established by using the testing procedures found in The Standard Test Method for Sulfur in Petroleum Products by Wvelength Dispersive X-Ray Fluorescence Spectrometry, ASTM D 2622, and is expressed in parts per million by weight ("PPMW") . Additionally, the percentage reduction of NOx ("NOxR"), toxic pollutants ("ToxR"), and VOCs ( "VOCR" ) were calculated using the Complex Model Phase I as prescribed by U.S. Federal Regulations, see, e.g., 40 C.F.R. § 80.45 (1999), such that the positive value indicates the percentage amount that emissions were reduced. As before, the gasoline-oxygenate blend designations shown in Table 10 correspond to the gasoline-oxygenate blend designations in Tables 8-9. For example, the gasoline-oxygenate blend designation Al corresponds to the gasoline-oxygenate blend designations shown in Tables 8-9 for gasoline-oxygenate blend Al . As previously discussed herein, each of these blend designation letters correspond to the neat blends shown in Table 6. The numerical designations following the letter designations are used to distinguish Phase I gasoline-oxygenate blends that have been prepared from the same neat blend. With these methods in mind, the following properties were found. TABLE 10: ADDITIONAL PHASE I GASOLINE-OXYGENATE BLEND PROPERTIES TABLE 10: (cont'd) ADDITIONAL PHASE I GASOLINE-OXYGENATE BLEND PROPERTIES Turning to the blends made after 1999, herein referred to as Phase II, the following neat blends recipes were formulated using the same method. TABLE 11 PHASE II NEAT BLEND RECIPES These neat blends were similarly tested online using certified online analyzers calibrated to ASTM standards and methods. The following Table 12 includes neat blend properties wherein each neat blend, designated by a letter designation AA-KK, corresponds to the same letter designation AA-KK from Table 11. With this correspondence in mind, the Phase II neat blends had the following properties prior to the introduction of oxygenates . TABLE 12 PHASE II NEAT BLEND RECIPES PROPERTIES Ul © As before, oxygenates were introduced via an oxygenate unit 14 in a line 52. To each of these blends, oxygenates were introduced such that the oxygenates of the blend comprised less than or equal to about ten (10) volume percent. Each of the gasoline-oxygenate blends contained denatured ethanol meeting ASTM D 4806 as the oxygenate . The following Table 13, entitled "Phase II Gasoline- Oxygenate Blend Recipes," shows a series of recipes relating to gasoline-oxygenate blends after the introduction of at least one oxygenate to the corresponding neat blends previously shown in Tables 11- 12. Of note, some of the neat blends AA-KK were used in the formulation of at least two gasoline-oxygenate blends. For example, neat blend D shown in Tables 11-12 was blended with ethanol to form a gasoline-oxygenate blend DD1 wherein the ethanol was 9.750 volume percent and gasoline-oxygenate blend DD2 wherein the ethanol content was 5.42 volume percent. Therefore, the gasoline-oxygenate blends DD1 and DD2 represent variations in the introduction of oxygenates to neat blend DD. The gasoline-oxygenate Phase II blend recipes shown in Table 13 are arranged such that the corresponding neat blend letter relates to the corresponding blend letter shown in Table 11-12. Similarly, the Phase II gasoline-oxygenate blend properties shown in Tables 14-15 correspond to the blend letter designations, and number designation, if applicable. Accordingly, Table 13, entitled "Phase II Gasoline-Oxygenate Blend Recipes," shows each gasoline- oxygenate blend recipe in terms of volume percent of the total blend after the introduction of oxygenates. TABLE 13: PHASE II GASOLINE-OXYGENATE BLEND RECIPES Ul Uι Using the laboratory ASTM testing procedures (found in ASTM D 2699, ASTM D 2700, ASTM D 5191, and ASTM D 86), each of the gasoline-oxygenate blends was tested offline using the appropriate ASTM procedure previously discussed herein. As before, each gasoline-oxygenate blend designation in Tables 14-15 corresponds to the gasoline- oxygenate blend recipe shown in Table 13. The following Phase II gasoline-oxygenate blend properties were determined. TABLE 14: PHASE II GASOLINE-OXYGENATE BLEND PROPERTIES Ul Ul Additional properties of the Phase II gasoline- oxygenate blends were determined using ASTM Standard and Methods as discussed herein. Of note, the percentage reduction of NOx ("NOxR"), toxic pollutants (ToxR"), and VOCs ("VOCR") were calculated using the Complex Model Phase II as described by Federal Regulations, see, e.g., 40 C.F.R. § 80.45(1999), such that the positive value indicates the percentage amount that emissions were reduced. TABLE 15: ADDITIONAL PHASE II GASOLINE-OXYGENATE PROPERTIES As the results of these tests show, the inclusion of oxygenates such as ethanol provides gasoline-oxygenate blends that produce a relatively low amount of gaseous pollutants with the reduction or elimination of MTBE as a fuel additive. Though the efforts shown above attempted to reduce or significantly eliminate the introduction of MTBE, those skilled in the art recognized that trace amount of MTBE and similar ethers may be introduced during the blending process. Certain blending agents or constituents may contain ether. The preferred embodiments of the present invention benefit from reducing the introduction of MTBE into the resulting gasoline-oxygenate blends. The blend of at least two hydrocarbon streams may produce gasoline-oxygenate blends having these desirable properties as well as low temperature and volatility. As the preferred embodiments show, gasoline-oxygenate blends may successfully include at least one alcohol, such as ethanol, while reducing pollution. With regard to the calculation of percentage of reduction of NOx, toxic pollutants, and/or VOCs, the mathematical models found in the 40 C.F.R. § 80.45 (1999) for Phase II Complex Model are currently more appropriate. Moreover, those skilled in the art will recognize that this disclosure has focused on rules, regulations, and requirements with regard to US EPA Region 1. Though the inventive concepts are clearly demonstrated in US EPA Region 1, there is no limitation to the scope of the disclosure or claims such that it is only applicable to US EPA Region 1. Future regulations may even be more restrictive than the requirements outlined in the Complex Model Phase II, Region 1 presented in US 40 C.F.R. § 80.45 (1999) .

Claims: C A I M S 1. A gasoline-oxygenate blend, suitable for use in an automotive spark-ignition engine, having the following properties : - (a) a Dry Vapour Pressure Equivalent (DVPE) less than 7.4 PSI (51 x 10 3 Pa), and (b) an alcohol content greater than 5 volume percent. 2. A gasoline-oxygenate blend according to Claim 1 having a DVPE of at least 6.5 PSI (44.8 x 10 3 Pa), and an alcohol content of up to 10 volume percent. 3. A gasoline-oxygenate blend according to Claim 1 or 2 , suitable for use in an automotive spark- ignition engine, having the following properties :- (a) A Dry Vapour Pressure Equivalent (DVPE) less than 7.2 PSI (49.6X10 3 Pa), and (b) an alcohol content greater than 5.0 volume percent, provided that when the alcohol content does not exceed 9.6 volume percent, the DVPE is less than 7.1 PSI (49 x 10 3 Pa), and when the alcohol content does not exceed 5.8 volume percent, the DVPE is less than 7 PSI (48.3 x 10 3 Pa). 4. A gasoline-oxygenated blend according to any one of Claims 1 to 3 wherein the oxygenate comprises ethanol . 5. A gasoline-oxygenate blend according to any one of Claims 1 to 4 which is substantially free of methyl t- butyl ether. 6. A gasoline-oxygenate blend according to any one of Claims 1 to 5 having an anti-knock index of at least 89. 7. A gasoline-oxygenate blend according to any one of Claims 1 to 6 having a DVPE less than 7.1 PSI (49 x 10 3 Pa), and an alcohol content greater than 5.8 volume percent . 8. A gasoline-oxygenate blend according to any one of Claims 1 to 6 having a DVPE less than 7 PSI (48.3 x 10 3 Pa), and an alcohol content greater than 5 volume percent . 9. A gasoline oxygenate blend according to any one of Claims 1 to 6 having a DVPE less than 7.2 PSI (49.6 x 10 3 Pa), and an alcohol content greater than 9.6 volume percent . 10. A process for preparing a gasoline-oxygenate blend according to any one of Claims 1 to 9 which comprises blending at least two hydrocarbon streams and at least one oxygenate to produce a gasoline-oxygenate blend having the following properties :- (a) a Dry Vapour Pressure Equivalent (DVPE) less than 7.4 PSI (51 x 10 3 Pa), and (b) an alcohol content greater than 5.0 volume percent .

Inventors: BARKER DAVID ALLEN, FUNK LLOYD ELBERT, LIEDER CHARLES ARTHUR, BARKER, DAVID, ALLEN, FUNK, LLOYD, ELBERT, LIEDER, CHARLES, ARTHUR
Applicants: SHELL INT RESEARCH, SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ B.V.
Application year: 2001
Main classification: C10L1
IPC codes: C10L1, C10L10