Olefinic renewable naphtha as gasoline blend component

Abstract

Olefinic naphtha compositions are provided that can be incorporated into naphtha boiling range fuel products, such as gasolines. The olefinic naphtha compositions can be formed as part of a process for oligomerization of olefins to form jet boiling range compounds. It has been unexpectedly discovered that olefinic naphtha formed from such an oligomerization process can be used to form naphtha and / or gasoline blends that have reduced aromatics content while maintaining volumetric energy density and maintaining or increasing octane rating (RON and / or MON).

Description

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of International Patent Application No. PCT / US2024 / 047933, filed 2024 Sep. 23, which claims the benefit of U.S. Provisional Application No. 63 / 585,004, filed 2023 Sep. 25. The entire contents of each of the foregoing applications are hereby incorporated by reference.FIELD

[0002] Naphtha boiling range blends that include olefinic renewable naphtha are provided, along with methods for making such blends.BACKGROUND

[0003] Interest in using renewable fuel continues to grow. Some current processes for forming renewable fuels correspond to processes for hydrotreating and dewaxing of vegetable oil to manufacture renewable diesel. Such processes also produce naphtha range hydrocarbon as a byproduct, which can be used as a gasoline blending component. However, the research octane number (RON) of the naphtha coming out of such processes is typically relatively low, ranging from about 45 to 60. The low octane number severely limits the types of gasoline blends that can be formed while still meeting minimum octane ratings set by regulation in various countries.

[0004] Other processes such as methanol to gasoline (MTG) and ethanol to gasoline (ETG) can produce a hydrocarbon gasoline blendstock from renewable feed. The products from these processes typically contain around 25 vol % to 40 vol % of aromatics. This contributes to such products having a relatively high research octane number (RON) of 92 to 99. The aromatic content, however, is also believed to contribute to production of particulate emissions.

[0005] A number of correlations are described in the literature between properties of a fuel and the potential for particulate emissions. One suggested method from the literature for correlating aromatic content with particulate emissions is the particulate emission index (PEI). The particulate emission index for a fuel can be calculated using Equation 1 where C#s correspond to vol % of aromatic compounds containing the specified number of carbon atoms. Equation 1 can be found in SAE Technical Paper 2019-01-1184 (2019).P⁢E⁢I=C⁢7+(2.5×C⁢8)+(5.8×C⁢9)+(4.8×C⁢10)+(35.3×(C⁢1⁢1+C⁢1⁢2+C⁢13))(1⁢0⁢0)(1)

[0006] Based on the literature, such as the SAE Technical Paper 2019-01-1184, PEI is a correlation that relates the composition of a gasoline to predicted particulate matter emissions from combustion in a spark ignition engine (also referred to as “sooting tendency”). Therefore, based on existing literature, a fuel composition with a lower PEI is desirable.

[0007] A journal article titled “A Review and Perspective on Particulate Matter Indices Linking Fuel Composition to Particulate Emissions from Gasoline Engines” describes other examples of correlation indices. (Leach et al., SAE Intl. J. Fuels Lubr. 15 (1) 2022.) Some early correlation methods, such as the threshold sooting index (TSI), use smoke point data and oxygenate content as correlations for particle emissions. A variation on this method is PASCE, which uses the amount of fuel evaporated at 170° C. and the molar ratio of carbon to hydrogen. Other examples of indices include the Menger / Wittman index, Particulate matter emissions index (PME), PMI, and RPMI. PME is a correlation based on a full detailed hydrocarbon analysis of a fuel. The Menger / Wittman index uses 14 parameters to provide a correlation for particulate emssions. PMI and RPMI are correlations based on the distillation properties of a fuel, optionally in combination with relative amounts of carbon and hydrogen.

[0008] U.S. Pat. No. 9,267,081 describes a process for using a bio-derived ethanol fraction and converting the fraction to gasoline.

[0009] U.S. Pat. No. 7,678,953 describes an olefin oligomerization process. The oligomerizaton process is used to make distillate boiling range compounds. A naphtha boiling range purge stream is also generated. An example describes the naphtha boiling range purge stream as having an olefin content of 75 wt % or more and a weight ratio of C8 olefins to C7 olefins of 10 or higher. It is noted that the naphtha boiling range purge stream was formed by oligomerizing a feed that was primarily composed of C4+ paraffins and olefins.

[0010] U.S. Pat. No. 7,692,049 describes an olefin oligomerization process to make distillate boiling range compounds. Naphtha boiling range recycle streams are also formed. In the examples, the naphtha boiling range recycle streams are described as having an olefin content of 65 wt % or more and a weight ratio of C8 olefins to C7 olefins of 10 or higher. It is noted that several example feeds were oligomerized in the examples. The feeds were primarily composed of C4+ paraffins and olefins.SUMMARY

[0011] In an aspect, an olefinic naphtha composition is provided that includes 35 wt % to 80 wt % olefins and 6.0 wt % or less aromatics, the composition having a weight ratio of C8 olefins to C7 olefins of 0.5 to 2.5 and a research octane number (RON) of 89 or higher.

[0012] In another aspect, a blended naphtha boiling range composition is provided. The blended naphtha boiling range composition includes 5.0 vol % to 50 vol % of the olefinic naphtha composition. Additionally, the blended naphtha boiling range composition includes 40 vol % to 95 vol % of a conventional naphtha, the conventional naphtha having an olefins content of less than 13 vol % and an aromatics content of 10 vol % to 20 vol %, relative to a weight of the conventional naphtha, the conventional naphtha comprising an anti-knock index (AKI) of 85 to 93, wherein the blended naphtha boiling range composition comprises an AKI of 87 or more and an olefins content of 5.0 vol % or more, relative to a weight of the blended naphtha boiling range composition.BRIEF DESCRIPTION OF THE DRAWINGS

[0013] FIG. 1 shows an example of a configuration for forming renewable fuels.

[0014] FIG. 2 shows a comparison of RON and PEI for various types of blended naphtha boiling range fractions.

[0015] FIG. 3 shows a comparison of RON and aromatics content for various types of blended naphtha fractions.

[0016] FIG. 4 shows a comparison of Lower Heating Value (LHV) versus aromatics content for various types of blended naphtha fractions.

[0017] FIG. 5 shows a comparison of LHV versus aromatics content for various types of blended naphtha fractions.DETAILED DESCRIPTION

[0018] In various aspects, olefinic naphtha compositions are provided that can be incorporated into naphtha boiling range fuel products, such as gasolines. The olefinic naphtha compositions can be formed as part of a process for oligomerization of olefins to form jet boiling range compounds. Such an oligomerization can be performed, for example, as part of a Methanol to Jet (MTJ) process, where methanol is converted to C3+ olefins, followed by oligomerization of the C3+ olefins to form jet boiling range compounds. It has been unexpectedly discovered that olefinic naphtha formed from such an oligomerization process can be used to form naphtha and / or gasoline blends that have reduced aromatics content while maintaining volumetric energy density and maintaining or increasing octane rating (RON and / or MON).

[0019] In various aspects, Methanol to Jet (MTJ) processes can produce aviation kerosene through olefins oligomerization. Such Methanol to Jet processes can also produce a naphtha range byproduct from renewable sources which can be used as a renewable gasoline blendstock.

[0020] It has been discovered that an olefinic naphtha composition generated by some MTJ processes is compositionally distinct from other renewable gasoline components and has an advantageous combination of properties, such as higher research octane number (RON) and / or higher motor octane number (MON) in combination with low aromatics and / or low PEI. In various aspects, the naphtha obtained from the olefin recycle stream can contain 35 wt % to 60 wt % olefins and 2.0 wt % or less of aromatics. The measured RON of this type of stream can be relatively high, such as 90 or more, or 93 or more, while still having a low aromatic content that allows for lower PEI. Concerns regarding potentially instability of high olefinic contents in gasoline can be addressed with appropriate antioxidant dosing and dilution with other gasoline blending components to meet specification.

[0021] Because the olefinic naphtha composition is fully hydrocarbon, the resulting naphtha composition can also have an energy content advantage over a blendstock such as ethanol. Ethanol has high octane while also having a low PEI owing to zero aromatics content. However, ethanol has a lower volumetric energy content as measured by Lower Heating Value (LHV).Definitions

[0022] In this discussion, unless otherwise specified, ASTM D6729 is used to determine the composition (paraffins, isoparaffins, olefins, naphthenes, aromatics) of a naphtha boiling range stream. Density is determined according to ASTM D4052. Research octane number (RON) and motor octane number (MON) are determined, respectively, according to ASTM D2699 and ASTM D2700. Lower heating value is determined according to ASTM D240.

[0023] In this discussion, unless otherwise specified, peroxide number is measured according to ASTM D3703. Induction period is measured according to ASTM D525. Gum content (washed or unwashed) is measured according to ASTM D381. Potential gums are measured according to ASTM D873. It is noted that ASTM D873 is typically specified for measuring gums in jet fractions, but it is used here to characterize gums in naphtha boiling range fractions.

[0024] In this discussion, the naphtha boiling range is defined as 28° C. to 210° C. Thus, the naphtha boiling range roughly starts at the boiling point of C5 paraffins and ends below the boiling point for a C10 n-paraffin. A naphtha boiling range composition, fraction, product, or other portion is defined as a composition, fraction, product, or other portion having a T10 distillation point of 28° C. or higher and a T90 distillation point of 210° C. or less. Distillation points are determined according to ASTM D2887. It is noted that in some optional aspects, a more limited portion of a naphtha boiling range may be of interest, such as a boiling range of 28° C. to 150° C.

[0025] In this discussion, a “naphtha composition” can refer to naphtha boiling range compositions at any stage of blending relative to gasoline formation. Thus, a naphtha composition includes unfinished blendstocks that include no additives or only limited numbers of additives; blendstocks prior to addition of oxygenates (with or without other additives); and finished blendstocks corresponding to gasolines.

[0026] In this discussion, the term “paraffin” refers to a saturated hydrocarbon chain. Thus, a paraffin is an alkane that does not include a ring structure. The paraffin may be straight-chain or branched-chain and is considered to be a non-ring compound. “Paraffin” is intended to embrace all structural isomeric forms of paraffins. The term “n-paraffin” has the expected definition of a straight chain alkane (no branches or rings in the carbon chain). The term “isoparaffin” is used herein to refer to any alkane that includes one or more branches in the carbon chain but does not include any ring structures.

[0027] In this discussion, an olefin refers to any compound that can be classified as an alkene under IUPAC naming rules (e.g., hydrocarbons that contain a double bond).

[0028] In this discussion, the term “naphthene” refers to a cycloalkane (also known as a cycloparaffin). Therefore, naphthenes correspond to saturated ring structures. The term naphthene encompasses single-ring naphthenes and multi-ring naphthenes. The multi-ring naphthenes may have two or more rings, e.g., two-rings, three-rings, four-rings, five-rings, six-rings, seven-rings, eight-rings, nine-rings, and ten-rings. The rings may be fused and / or bridged. The naphthene can also include various side chains, such as one or more alkyl side chains of 1-10 carbons.

[0029] In this discussion, the term “aromatic ring” means five or six atoms joined in a ring structure wherein (i) at least four of the atoms joined in the ring structure are carbon atoms and (ii) all of the carbon atoms joined in the ring structure are aromatic carbon atoms. Therefore, aromatic rings correspond to unsaturated ring structures. Aromatic carbons can be identified using, for example, 13C Nuclear Magnetic Resonance. Aromatic rings having atoms attached to the ring (e.g., one or more heteroatoms, one or more carbon atoms, etc.) but which are not part of the ring structure are within the scope of the term “aromatic ring.” Additionally, it is noted that ring structures that include one or more heteroatoms (such as sulfur, nitrogen, or oxygen) can correspond to an “aromatic ring” if the ring structure otherwise falls within the definition of an “aromatic ring”.

[0030] In this discussion, the term “non-aromatic ring” means four or more carbon atoms joined in at least one ring structure wherein at least one of the four or more carbon atoms in the ring structure is not an aromatic carbon atom. Non-aromatic rings having atoms attached to the ring (e.g., one or more heteroatoms, one or more carbon atoms, etc.), but which are not part of the ring structure, are within the scope of the term “non-aromatic ring.”

[0031] In this discussion, the term “aromatics” refers to all compounds that include at least one aromatic ring. Such compounds that include at least one aromatic ring include compounds that have one or more hydrocarbon substituents. It is noted that a compound including at least one aromatic ring and at least one non-aromatic ring falls within the definition of the term “aromatics”.

[0032] It is noted that that some hydrocarbons present within a feed or product may fall outside of the definitions for paraffins, naphthenes, and aromatics. For example, any alkenes that are not part of an aromatic compound would fall outside of the above definitions. Similarly, non-aromatic compounds that include a heteroatom, such as sulfur, oxygen, or nitrogen, are not included in the definition of paraffins or naphthenes.Properties of Olefinic Naphtha Composition and Resulting Blends

[0033] In various aspects, an olefinic naphtha composition generated from an olefin oligomerization process as described herein can have a variety of properties that allow the olefinic naphtha composition to be beneficial as a blend component for naphtha / gasoline boiling range compositions.

[0034] In various aspects, the olefinic naphtha composition can have an olefin content of 35 wt % to 80 wt %, or 40 wt % to 80 wt %, or 50 wt % to 80 wt %, or 35 wt % to 65 wt %, or 40 wt % to 65 wt %, or 35 wt % to 55 wt %, or 40 wt % to 55 wt %. Additionally, the olefinic naphtha composition can have a weight ratio of C8 olefins to C7 olefins of 2.5 or less. For example, the weight ratio of C8 olefins to C7 olefins can be 0.5 to 2.5, or 0.5 to 2.0, or 0.5 to 1.5, or 1.0 to 2.5, or 1.0 to 2.0, or 1.0 to 1.5.

[0035] In addition to olefins, in some aspects the olefinic naphtha composition can have an aromatics content of 0.1 wt % to 6.0 wt %, or 1.0 wt % to 6.0 wt %, or 0.1 wt % to 5.0 wt %, or 1.0 wt % to 5.0 wt %, or 0.1 wt % to 4.0 wt %, or 1.0 wt % to 4.0 wt %. Additionally or alternately, in some aspects the olefinic naphtha composition can have a naphthenes content of 1.0 wt % to 20 wt %, or 1.0 wt % to 15 wt %, or 1.0 wt % to 10 wt %, or 1.0 wt % to 5.0 wt %, or 5.0 wt % to 20 wt %, or 5.0 wt % to 15 wt %.

[0036] In various aspects, the olefinic naphtha composition can have an n-paraffin content of 3.0 wt % to 10 wt %, or 3.0 wt % to 8.0 wt %, or 5.0 wt % to 10 wt %. Additionally or alternately, the olefinic naphtha composition can have an isoparaffin content of 12 wt % to 30 wt %, or 15 wt % to 30 wt %, or 12 wt % to 25 wt %, or 15 wt % to 25 wt %. Further additionally or alternately, the olefinic naphtha composition can have a weight ratio of isoparaffins to n-paraffins of 2.5 to 7.5, or 2.5 to 5.0.

[0037] In various aspects, the olefinic naphtha composition can correspond to a naphtha boiling range composition. In some aspects, the olefinic naphtha composition can have a T10 distillation point of 30° C. or more and a T90 distillation point of 210° C. or less, or 150° C. or less.

[0038] In various aspects, the olefinic naphtha composition can have a density at 15° C. of 0.700 g / ml to 0.735 g / ml, or 0.700 g / ml to 0.725 g / ml, or 0.710 g / ml to 0.735 g / ml, or 0.710 g / ml to 0.725 g / ml. In various aspects, the olefinic naphtha composition can have a RON of 90 to 98, or 92 to 98. Additionally or alternately, the olefinic naphtha composition can have a MON of 80 to 88, or 82 to 88. Still further additionally or alternately, the olefinic naphtha composition can have an anti-knock index (calculated as RON+MON / 2) of 85 to 93, or 87 to 93, or 85 to 91, or 87 to 91.

[0039] It is noted that the olefinic naphtha composition has a high content of olefins relative to conventional blend components for naphtha. Due to the high olefin content, the olefinic naphtha composition, prior to modification, can have a peroxide number of 300 or more, or 500 or more. This can be corrected, however, by addition of commercial anti-oxidants in typical or conventional treatment amounts. Examples of anti-oxidants are phenylene diamine or a blend of phenylene diamine and a hindered phenol. In various aspects, the amount of antioxidant added to an olefinic naphtha composition can correspond to 25 wppm to 1200 wppm, or 100 wppm to 1200 wppm, or 25 wppm to 600 wppm, or 100 wppm to 600 wppm. After blending, the amount of antioxidant in a blended naphtha composition (such as a gasoline composition) can be 10 wppm to 240 wppm, or 10 wppm to 150 wppm, or 10 wppm to 120 wppm. When an anti-oxidant is added, the peroxide number for the olefinic naphtha composition can be 25 or less, or 15 or less, such as down to 0.

[0040] In various aspects, an olefinic naphtha composition can have a lower heating value (on a volumetric basis) of 30.0 MJ / L or higher, or 31.0 MJ / L or higher, such as up to 33.0 MJ / kg or possibly still higher.

[0041] An olefinic naphtha composition (including a typical amount of an antioxidant) can be used as a blend component for forming a gasoline composition. In various aspects, a blended gasoline composition can include 5.0 vol % to 50 vol % of the olefinic naphtha composition, or 10 vol % to 50 vol %, or 20 vol % to 50 vol %, or 5.0 vol % to 42 vol %, or 10 vol % to 42 vol %, or 20 vol % to 42 vol %, or 5.0 vol % to 35 vol %, or 10 vol % to 35 vol %. Of course, smaller amounts (less than 5.0 vol %) of an olefinic naphtha composition could also be added to a blend, but at low volumes, the impact of the olefinic naphtha composition on the resulting blend is reduced or minimized.

[0042] Another component of a gasoline blend can be a conventional gasoline and / or naphtha fraction. In some aspects, the balance of the gasoline blend can be a conventional gasoline and / or naphtha fraction. In other aspects, other components can be included in the blend in addition to the conventional gasoline and / or naphtha fraction and the olefinic naphtha composition. In various aspects, a blend can include 40 vol % to 95 vol % of a conventional gasoline and / or naphtha composition.

[0043] Typical conventional and / or commercial gasolines have olefin contents of less than 13 vol %, or 6.0 vol % or less, or 3.0 vol % or less, such as down to having substantially no olefin content (0.1 vol % or less). Such conventional and / or commercial gasolines can also have aromatics contents of 5 vol % to 35 vol %, or 5 vol % to 20 vol %, or 5 vol % to 18 vol %, or 5 vol % to 15 vol %, or 10 vol % to 35 vol %, 10 vol % to 20 vol %, or 10 vol % to 18 vol %, or 10 vol % to 15 vol %.

[0044] In some aspects, a conventional gasoline or naphtha fraction can have an AKI of 87 to 95, or 87 to 93, or 87 to 91. In alternative aspects, the conventional gasoline in a blend can be a gasoline with an AKI that is lower than the AKI of the olefinic naphtha component. In such aspects, the AKI of the conventional gasoline can be lower than the AKI of the olefinic naphtha composition by 1 or more, or 2 or more, or 3 or more, such as up to 5 or possibly still more. In such aspects, the conventional gasoline or naphtha can have an AKI of 83 to 89, or 83 to 86, or 85 to 89. In addition to a conventional gasoline and / or naphtha fraction, a blend can include any other conventional additives or other components typically found in a gasoline.

[0045] In some aspects, ethanol can also be included in a blend. Ethanol is commonly blended into gasolines in amounts up to 15 vol %. In some aspects, a blend including an olefinic naphtha composition and a conventional gasoline or naphtha fraction can further include 1.0 vol % to 15 vol % of ethanol, or 1.0 vol % to 10 vol %, or 5.0 vol % to 15 vol %, or 5.0 vol % to 10 vol %.

[0046] In some aspects, the blend can further include one or more other renewable components to counteract disadvantages typically caused by such renewable components. For example, a blend including a conventional gasoline and / or naphtha fraction and an olefinic naphtha composition can further include a highly aromatic renewable naphtha. The low aromatic content of the olefinic naphtha composition can allow an increased amount of a highly aromatic naphtha fraction to be added while still maintaining an aromatics content of 15 vol % or less. An olefinic naphtha composition can similarly be used to reduce the aromatics content of conventional naphtha fractions that have aromatics content of 15 vol % or more.

[0047] More generally, a blend including an olefinic naphtha composition and a conventional gasoline and / or naphtha fraction can have an aromatics content of 8.0 vol % to 15 vol %, or 8.0 vol % to 12 vol %, or 10 vol % to 15 vol %. Additionally or alternately, the blend can have an olefins content of 5.0 vol % to 24 vol %, or 5.0 vol % to 20 vol %, or 5.0 vol % to 18 vol %, or 10 vol % to 24 vol %, or 10 vol % to 20 vol %, or 10 vol % to 18 vol %, or 5.0 vol % to 12 vol %.

[0048] It is noted that the olefins content of a blend can largely be due to the olefins from the olefinic naphtha composition. As a result, the distribution of olefins in the blend can at least partially reflect the distribution of olefins from the olefinic naphtha composition. In some aspects, the blend can have a weight ratio of C8 olefins to C7 olefins of 0.5 to 2.5, or 0.5 to 2.0, or 0.5 to 1.5, or 1.0 to 2.5, or 1.0 to 2.0, or 1.0 to 1.5.

[0049] In various aspects, a blend including a conventional gasoline and / or naphtha fraction and an olefinic naphtha composition can have an AKI of 87 to 93, or 87 to 91, or 89 to 93. Additionally or alternately, such a blend can have a RON of 89 to 97, or 89 to 93, or 91 to 97.Oligomerization Process

[0050] In various aspects, an olefinic naphtha stream can be formed as a side stream from an olefin oligomerization process. In such an olefin oligomerization process, a feed containing at least one C3 to C12 olefin together with an olefinic recycle stream containing no more than 10 wt. % C10+ non-normal olefins can be oligomerized over a molecular sieve catalyst such that a) the recycle to fresh feed weight ratio is from about 0.5 to about 2.0 and b) the difference between the highest and lowest temperatures within the reactor is 80° F. (45° C.) or less. The oligomerization product is then separated into a heavy iso-olefinic stream and at least one light olefinic stream. At least part of the light olefinic stream(s) is then recycled to the oligomerization process. Another portion of the light olefinic stream(s) can be used to form an olefinic naphtha composition that can be used as a gasoline blend component. In various aspects, the heavy iso-olefinic stream can be exposed to hydroprocessing conditions to produce an isoparaffinic stream.

[0051] The fresh feed to the oligomerization process can include any single C3 to C12 olefin or any mixture thereof in any proportion. Particularly suitable feeds include mixtures of propylene and butylenes having at least 5 wt %, such as at least 10 wt %, for example at least 20 wt %, such as at least 30 wt % or at least 40 wt % C4 olefin. Also useful are mixtures of C3 to C5 olefins having at least 415 wt % C4 olefin, at least 5 wt % C5 olefin, and at least 1.0 wt % C6 olefin. Still other useful feeds are feeds that include 20 wt % or more of propylene, or 30 wt % or more, while also containing 30 wt % or less of C4 compounds and / or 25 wt % or less of C4 olefins.

[0052] In one aspect, the olefinic feed to the oligomerization process is obtained by the conversion of an oxygenate, such as methanol, to olefins over a either silicoaluminophosphate (SAPO) catalyst, according to the method of, for example, U.S. Pat. Nos. 4,677,243 and 6,673,978, or an aluminosilicate catalyst, according to the method of, for example, WO04 / 18089, WO04 / 16572, EP 0 882 692 and U.S. Pat. No. 4,025,575. Alternatively, the olefinic feed can be obtained by the catalytic cracking of relatively heavy petroleum fractions, or by the pyrolysis of various hydrocarbon streams, ranging from ethane to naphtha to heavy fuel oils, in admixture with steam, in a well understood process known as “steam cracking”.

[0053] In various aspects, the feed to the oligomerization process also contains an olefinic recycle stream containing no more than 10 wt % C10+ non-normal olefins and / or having a final boiling point of 170° C. or less. In some aspects, the olefinic recycle stream can include 30 wt % or less of C9+ olefins, or 10 wt % or less and / or have a final boiling point of 140° C. or less. Additionally or alternately, in some aspects, the olefinic recycle stream contains 30 wt % or less of C4 hydrocarbons, or 5.0 wt % or less (therefore roughly corresponding to a de-butanized stream). The amount of olefinic recycle stream fed to the oligomerization process is such that the recycle to fresh feed weight ratio is from about 0.5 to about 2.0. More particularly, the mass ratio of olefinic recycle stream to fresh olefinic feedstock can be at least 0.6 or at least 0.9, but generally is no greater than 1.8, or no greater than 1.5 or no greater than 1.3. In some aspects, the olefinic naphtha composition corresponds to a second portion of the stream used to form the olefinic recycle stream.

[0054] In addition, the feedstock, the recycle or both may comprise other materials, such as an inert diluent, for example, a saturated hydrocarbon, or other hydrocarbon species, such as aromatics or dienes.

[0055] The catalyst used in the oligomerization process can include any crystalline molecular sieve which is active in olefin oligomerization reactions. In one embodiment, the catalyst includes a medium pore size molecular sieve having a Constraint Index of about 1 to about 12. Constraint Index and a method of its determination are described in U.S. Pat. No. 4,016,218, which is incorporated herein by reference. Examples of suitable medium pore size molecular sieves are those having 10-membered ring pore openings and include those of the TON framework type (for example, ZSM-22, ISI-1, Theta-1, Nu-10, and KZ-2), those of the MTT framework type (for example, ZSM-23 and KZ-1), of the MFI structure type (for example, ZSM-5), of the MFS framework type (for example, ZSM-57), of the MEL framework type (for example, ZSM-11), of the MTW framework type (for example, ZSM-12), of the EUO framework type (for example, EU-1), of the MRE framework type (for example, ZSM-48), of the NES framework type (for example, Nu-87), of the IFW framework type (for example, ITQ-52), of the ITH framework type (for example, ITQ-13), of the ITR framework type (for example, ITQ-34), and members of the ferrierite family (for example, ZSM-35). In one preferred embodiment, the molecular sieve catalyst comprises ZSM-5.

[0056] Other examples of suitable molecular sieves include those having 12-membered pore openings, such as ZSM-18, zeolite beta, faujasites, zeolite L, mordenites, MCM-68, as well as members of MCM-22 family of molecular sieves (including, for example, MCM-22, PSH-3, SSZ-25, ERB-1, ITQ-1, ITQ-2, MCM-36, MCM-49 and MCM-56).

[0057] In one embodiment, the crystalline aluminosilicate molecular sieve has an average (d50) crystal size no greater than 0.05 micron. In addition, the molecular sieve is preferably selected so as to have an alpha value between about 100 and about 650, conveniently between about 200 and about 600, or between about 250 and about 500. The alpha value of a molecular sieve is an approximate indication of its catalytic cracking activity compared with a standard silica-alumina catalyst test (with an alpha value of 1). The alpha test is described in U.S. Pat. No. 3,354,078; in the Journal of Catalysis, Vol. 4, p. 527 (1965); Vol. 6, p. 278 (1966); and Vol. 61, p. 395 (1980), each incorporated herein by reference as to that description. The experimental conditions of the test used herein include a constant temperature of 538° C. and a variable flow rate as described in detail in the Journal of Catalysis, Vol. 61, p. 395. Conveniently the crystalline aluminosilicate molecular sieve having a silica to alumina molar ratio of about 20 to about 300, such as about 20 to about 150, for example about 45 to about 90.

[0058] The molecular sieve may be supported or unsupported, for example in powder form, or used as an extrudate with an appropriate binder. Where a binder is employed, the binder is conveniently a metal oxide, such as alumina, and is present in an amount such that the oligomerization catalyst contains between about 2 and about 80 wt. % of the molecular sieve.

[0059] The oligomerization reaction should be conducted at sufficiently high WHSV of fresh feed to the reactor to ensure the desired low level of C17+ oligomers in the reaction product. This can correspond to a WHSV (weight hourly space velocity) of 1.0 or more on a weight of fresh feed versus weight of catalyst basis. With regard to the combined fresh olefin feed and recycle to the reactor, the WHSV can be 1.5 or more, again based on the amount of the oligomerization catalyst.

[0060] The oligomerization process can be conducted over a wide range of temperatures, although generally the temperature within the oligomerization reaction zone should be between about 160° C. and 320° C. It is, however, important to ensure that the temperature across the reaction zone is maintained relatively constant so as to produce the desired level of C4 olefin conversion at a given WHSV and point in the reaction cycle. Thus, as discussed above, the difference between the highest and lowest temperatures within the reactor should be maintained at 80° F. (45° C.) or less.

[0061] The oligomerization process can be conducted over a wide range of olefin partial pressures, although higher olefin partial pressures are preferred since low pressures tend to promote cyclization and cracking reactions, and are thermodynamically less favorable to the preferred oligomerization reaction. Typical olefin partial pressures of olefins in the combined olefinic feed and light olefinic / recycle stream as total charge to the reactor comprise at least 400 psig (2860 kPa).

[0062] As synthesized, the resulting oligomerized product can be exposed to any convenient olefin saturation process, such as a mild hydrotreatment process, to form a product rich in isoparaffins. Mild hydroprocessing can generally convert iso-olefins to isoparaffins with a reduced or minimized amount of reduction in the size of the carbon chains in a fraction. In addition to converting iso-olefins to isoparaffins, hydroprocessing of a kerosene fraction can also be used to remove sulfur, remove nitrogen, saturate olefins, saturate aromatics, and / or for other purposes.Configuration Example

[0063] FIG. 1 shows an example of an oligomerization process. In the example shown in FIG. 1, an olefinic feed 105 is combined with first recycle stream 106 and / or second recycle stream 107 prior to entering oligomerization reactor 110. Optionally, the olefinic feed 105 and the recycle streams can be mixed in a pre-mixing stage prior to entering oligomerization reactor 110. Oligomerization reactor 110 can be any convenient type of oligomerization reactor for oligomerization of olefins. The oligomerization reactor produces an oligomerization effluent 115. The oligomerization effluent 115 can be separated in a sequence of separators (such as fractionators) 120 and 130. A first separation in separator 120 results in formation of distillate product 149 and lighter fraction 125. A portion 121 of lighter fraction 125 can optionally be recycled to oligomerization reactor 110, while a remaining portion 129 can be passed into separator 130. Separator 130 produces a light C4− purge stream 142 and a stream enriched in C5-C8 olefins 135. A portion 139 of stream 135 can be withdrawn as an olefinic naphtha composition, while the rest of stream 135 is recycled to oligomerization reactor 110.Example 1—Olefinic Naphtha Composition

[0064] A configuration similar to FIG. 1 was used to oligomerize a feed to form jet boiling range compounds, along with an olefinic naphtha composition. Table 1 shows the composition of the feed used for the oligomerization reaction.TABLE 1Feed for Oligomerization to form Olefinic Naphtha CompositionComponentFormulawt %PropyleneC3H637.55ButadieneC4H60.06IsobutyleneC4H80.451-ButeneC4H826.09isobutaneC4H103.011-PenteneC5H104.711-HexeneC6H1228.00Dimethyl etherC2H6O0.03AcetoneC3H6O0.10Total100

[0065] As shown in Table 1, the feed for the oligomerization reaction included more than 30 wt % of C3 olefins (propylene).

[0066] Table 2 shows compositional details for an olefinic naphtha composition as described herein. The olefinic naphtha composition was formed during oligomerization of the feed shown in Table 1. In addition to the primary compositional analysis according to ASTM D6729, a compositional analysis based on gas chromatography / mass spectrometry is also shown.TABLE 2Compositional Analysis of Olefinic Naphtha CompositionDHAASTM D6729GC / MSn-ParaffinsC40.005—C50.043—C60.5380.9C71.8832.0C83.561.2C90.013—IsoparaffinsC40.009—C50.1070.1C62.7352.4C75.4365.2C87.0710.1C95.875—OlefinsC40.012—C51.6871.6C610.58310.6C716.22512.8C810.42427.2C92.088—NaphthenicC60.1493.6C74.0151.1C85.359—C91.32—AromaticsC61.027—C70.852—C80.974—UnknownsC60.012C72.432C810.587C94.97221 (olefins +naphthenic)

[0067] As shown in Table 2, based on ASTM D6729, the olefin content of the naphtha composition is roughly 40 wt %. The weight ratio of C8 olefins to C7 olefins is less than 1.0. The aromatics content is 3.0 wt % or less, while the naphthenes content is less than 11 wt %. Additionally, the weight ratio of isoparaffins to n-paraffins is between 3.0 and 5.0.

[0068] Due in part to the high olefin content, the olefinic naphtha composition alone is somewhat susceptible to oxidation. The stability of the olefinic naphtha composition can be improved by adding an antioxidant. Table 3 shows density, octane numbers, and peroxide number values for the olefinic naphtha composition (ONC) in Table 1, along with samples of the olefinic naphtha composition where an antioxidant has been added. In Table 3, the antioxidant corresponding to “AO1” is based on phenylene diamine, while “AO2” is based on a combination of phenylene diamine and a hindered phenol.TABLE 3Characterization of Olefinic NaphthaCompositions with AntioxidantsONC +ONC +MethodONC neatAO1AO2Density (g / ml)ASTM——0.716D4052RONASTM—9393D2699MONASTM—8282D2700PeroxideASTM92015.68.5numberD3703(mg / kg)

[0069] As shown in Table 3, the olefinic naphtha composition has a density of 0.716 g / ml. It is noted that due to the small quantity of antioxidants used in the ONC+AO2 composition, the presence of AO2 is expected to have minimal impact on the density. The antioxidants are also not expected to affect the RON or MON values. However, the antioxidants do substantially reduce the peroxide number for the compositions. It is noted that the 920 value for the peroxide number of the neat ONC composition is outside of the test method range, but the exact value is not critical. It is clear that the peroxide number for the neat ONC is higher than desirable for use in a commercial gasoline product. By adding either of the antioxidants in a typical treatment amount, the peroxide number is reduced to an acceptable level for use as a blend component in a gasoline composition.Example 2—Stability of Gasoline Blends

[0070] The olefinic naphtha compositions shown in Table 3 were blended with commercial gasoline to create a final blend that contained a total of approximately 18-24% olefins. Table 4 shows results from characterization of stability properties for the resulting gasoline blends.TABLE 4Stability of Gasoline Blends ContainingOlefinic Naphtha CompositionsONCONC +ONC +MethodUnitsneatAO1AO2InductionASTMmins58>1000>1000periodD525PeroxideASTMmg / kg183*9.4210.4numberD3703UnwashedASTMmg / 100 mL  <0.5<0.5<0.5gumsD381WashedASTMmg / 100 mL  <0.5<0.5<0.5gumsD381PotentialASTMmg / 100 mL 111gumsD873-MOD

[0071] As shown in Table 4, the gasoline blend containing the neat olefinic naphtha composition (without antioxidant) showed a low induction period (ASTM D525) of 58 minutes, which is significantly lower than the US gasoline requirement ASTM D4814 of >240 mins. By contrast, the gasoline blends including the olefinic naphtha compositions treated with an antioxidant had induction periods of greater than 1000 mins. Similarly, the peroxide number was also high for the blend without antioxidant, while low peroxide numbers were observed for the blends where the olefinic naphtha composition included antioxidant.Example 3—Blended Compositions

[0072] A series of blended gasoline compositions were made by blending a commercial gasoline with various types of renewable blend components. Table 5 shows the blend components that were used to make the various blends.TABLE 5Blend ComponentsONC +AromaticAromaticRenewable naphthaCommercialAO2Naphtha 1Naphtha 2ABCEthanolgasolineRON93.485.092.940394110985.2PEI0.041.6662.4650.0090.0070.30900.788Density,716.3761.2757.8670.4n.d.695.3789714.5kg / m3LHV,44.0044.66n.d.40.76n.d.42.7326.943.92MJ / kgLHV,31.5234.00n.d.27.33n.d.29.7121.2231.38MJ / LOlefins,41.3653.268.7140.0750.2191.95203.410vol %Aromatics,vol %C70.6992.9253.09740.0120.0030.16904.469C80.8019.4859.36580.2670.1702.19506.145C9011.53012.62590.020.0261.87804.084C1002.8439.04010.0150.0001.02901.165C1100.6560.817500.0000.16900.619C1201.0282.110800.0000.09900.221C13000.000000Total1.50028.46737.0580.3140.2025.5400.00016.700

[0073] In Table 5, “ONC+AO2” is the corresponding olefinic naphtha composition shown in Tables 3 and 4. The “Aromatic Naphtha 1” and “Aromatic Naphtha 2” compositions correspond to commercially available aromatic-containing naphtha boiling range compositions that are formed from a bio-ethanol-to-gasoline process. The “renewable naphtha” compositions correspond to naphtha fractions formed from hydroprocessing of distillate boiling range bio-derived feedstocks. The renewable naphtha compositions have a relatively high content of paraffins. The “ethanol” corresponds to a typical ethanol, such as an ethanol that could be derived from renewable sources. The commercial gasoline is a conventional gasoline

[0074] FIG. 2 and FIG. 3 provide comparisons between the olefinic naphtha composition and naphtha compositions derived from other renewable processes that are shown in Table 5. In FIG. 2, the olefinic naphtha composition shows an unexpected combination of relatively high RON and low PEI compared to naphthas from other processes.

[0075] In FIG. 3, the same unexpected observation is made when RON is compared to total aromatic contents. It is noted that in the PEI calculation, different aromatics have different weights in contributing to the emissions. This accounts for the difference in shape between FIG. 2 and FIG. 3.

[0076] The blend components in Table 5 were used to make various of gasoline blends. A first series of gasoline blends are shown in Table 6. The gasoline blends in Table 6 were formulated in order to maintain an AKI (i.e., (RON+MON) / 2) of 87. In Table 6, the “naphtha” row corresponds to the weight percentage of the naphtha composition shown at the top of each column. Additionally, it is noted that because the AKI of the olefinic naphtha composition is similar to the AKI of the commercial gasoline, the amount of the olefinic naphtha composition was limited so that the olefin content was roughly 18 vol %. Because current commercial gasolines currently include 10 vol % of ethanol, where possible the blends were prepared to include 10 vol % of ethanol.TABLE 6Gasoline Blends at Constant AKIBlend 1Blend 2Blend 3Blend 4Blend 5NaphthaONC +AromaticAromaticRenew.CommercialAO2Naphtha 1Naphtha 2NaphthagasolineABlendrecipe,vol %Ethanol10701510Naphtha399370120Commercial510307390gasolineLHV30.4233.133.129.3730.37(MJ / L)Olefins17.93.07.12.53.1(vol %)C7-C139.126.531.012.215.0Aromatics(vol %)RON90.889.591.188.989.9MON83.784.983.185.185.3AKI87.287.287.187.0087.6

[0077] As shown in Table 6, the olefinic naphtha composition can be blended with the commercial gasoline in substantial amounts so that AKI is maintained at 87 while also reducing the aromatics content of the gasoline blend. The ability to form such high AKI blends while reducing aromatics content is due to the unexpected combination of high RON and low aromatics in the olefinic naphtha composition. This is in contrast to the blends containing Aromatic Naphtha 1 and Aromatic Naphtha 2, where the high aromatics contents of the aromatic naphthas result in a substantial increase in aromatics content when blended in substantial amounts into a gasoline. Additionally, the volumetric energy content of the olefinic naphtha composition is comparable to the commercial gasoline, so that energy density is not reduced by adding the olefinic naphtha composition. This is in contrast to the renewable naphtha blend components, which result in a loss of volumetric energy content as illustrated by the lower heating value per volume.

[0078] FIG. 4 illustrates the relationship between energy density and aromatics content for the gasoline blends shown in Table 6, which each have roughly the same AKI of 87. In FIG. 4, line 410 corresponds to the lower heating value per volume of the commercial gasoline prior to blending, while line 420 corresponds to the aromatics content of the commercial gasoline prior to blending. At constant AKI, in order to reduce net emissions, either the lower heating value per volume can be increased at constant aromatics can be increased, or the aromatics content at constant lower heating value can be reduced. Of course, increasing the lower heating value while reducing the aromatics content would also be beneficial. As shown in FIG. 4, blending the olefinic naphtha composition with the commercial gasoline results in a blended gasoline with the same lower heating value per volume as the commercial gasoline while having substantially reduced aromatics content. This is in contrast to the blends including renewable naphtha A or renewable naphtha C, where both the lower heating value and the aromatics are reduced.

[0079] In another series of blends, instead of holding AKI constant, the amount of renewable naphtha included in the blend was maintained at 20 vol %. Table 7 shows this second series of blended gasoline compositions.TABLE 7Gasoline Blends at Constant Renewable ContentBlend 6Blend 7Blend 8Blend 9Blend 10NaphthaONC +AromaticAromaticRenew.CommercialAO2Naphtha 1Naphtha 2NaphthagasolineABlendrecipe,vol %Ethanol1010101010Naphtha2020202020Commercial7070707070gasolineLHV30.3930.8930.8629.5530.37(MJ / L)Olefins10.73.04.12.43.1(vol %)C7-C1312.017.419.111.815.0Aromatics(vol %)RON90.590.692.182.989.9MON84.585.786.181.485.3AKI87.588.189.182.287.6

[0080] As shown in Table 7, the gasoline blend including the olefinic naphtha composition provides a beneficial combination of reducing aromatics content while maintaining or increasing both octane and lower heating value per volume. This is illustrated in FIG. 5. Table 7 also shows the substantial increase in olefins content that is provided by using an olefinic naphtha composition as a blend component, even with only 20 vol % of the blend corresponding to the olefinic naphtha composition.Additional Embodiments

[0081] Embodiment 1. An olefinic naphtha composition comprising 35 wt % to 80 wt % olefins and 6.0 wt % or less aromatics, the composition comprising a weight ratio of C8 olefins to C7 olefins of 0.5 to 2.5 and a research octane number (RON) of 89 or higher.

[0082] Embodiment 2. The olefinic naphtha composition of Embodiment 1, wherein the composition further comprises 1.0 wt % to 10 wt % of n-paraffins, or wherein the composition further comprises 1.0 wt % to 20 wt % of naphthenes, or a combination thereof.

[0083] Embodiment 3. The blended naphtha boiling range composition of any of the above embodiments, wherein the olefinic naphtha composition comprises a T10 distillation point of 28° C. or more and a T90 distillation point of 210° C. or less.

[0084] Embodiment 4. The olefinic naphtha composition of any of the above embodiments, wherein the composition comprises a T90 distillation point of 150° C. or less.

[0085] Embodiment 5. The olefinic naphtha composition of any of the above embodiments, wherein the olefinic naphtha composition comprises 40 wt % to 55 wt % olefins, or wherein the olefinic naphtha composition comprises a lower heating value of 30.0 MJ / kg or higher, or a combination thereof.

[0086] Embodiment 6. The olefinic naphtha composition of any of the above embodiments, wherein the composition comprises a weight ratio of isoparaffins to n-paraffins of 2.5 to 7.5.

[0087] Embodiment 7. The olefinic naphtha composition of any of the above embodiments, wherein the olefinic naphtha composition comprises an AKI of 87 or higher.

[0088] Embodiment 8. A blended naphtha boiling range composition comprising: 5.0 vol % to 50 vol % of an olefinic naphtha composition according to any of Embodiments 1 to 5, and 40 vol % to 95 vol % of a conventional naphtha, the conventional naphtha having an olefins content of less than 13 vol % and an aromatics content of 10 vol % to 20 vol %, relative to a weight of the conventional naphtha, the conventional naphtha comprising an anti-knock index (AKI) of 85 to 93, wherein the blended naphtha boiling range composition comprises an AKI of 87 or more and an olefins content of 5.0 vol % or more, relative to a weight of the blended naphtha boiling range composition.

[0089] Embodiment 9. The blended naphtha boiling range composition of Embodiment 8, wherein the blended naphtha boiling range composition comprises 15 wt % or less aromatics relative to a weight of the blended naphtha boiling range composition.

[0090] Embodiment 10. The blended naphtha boiling range composition of Embodiment 8 or 9, wherein the conventional naphtha comprises 6.0 vol % or less of olefins.

[0091] Embodiment 11. The blended naphtha boiling range composition of any of Embodiments 8 to 10, wherein the blended naphtha boiling range composition further comprises 10 wppm to 240 wppm of an antioxidant additive, or wherein the blended naphtha boiling range composition further comprises 1.0 vol % to 15 vol % of ethanol, or a combination thereof.

[0092] Embodiment 12. The blended naphtha boiling range composition of any of Embodiments 8 to 11, wherein the blended naphtha boiling range composition comprises a weight ratio of C8 olefins to C7 olefins of 0.5 to 2.5.

[0093] Embodiment 13. The blended naphtha boiling range composition of any of Embodiments 8 to 12, wherein the blended naphtha boiling range composition comprises an olefins content of 10 wt % or more.

[0094] Embodiment 14. The blended naphtha boiling range composition of any of Embodiments 8 to 13, wherein the AKI of the blended naphtha boiling range composition is lower than an AKI of the olefinic naphtha composition, or wherein a RON of the blended naphtha boiling range composition is lower than the RON of the olefinic naptha composition, or a combination thereof.

[0095] Embodiment 15. A method for forming a blended naphtha boiling range composition according to any of Embodiments 8 to 14, comprising: mixing a) 5.0 vol % to 50 vol % of an olefinic naphtha composition comprising 35 wt % to 80 wt % olefins and 6.0 wt % or less aromatics, relative to a weight of the olefinic naphtha composition, the olefinic naphtha composition comprising a weight ratio of C8 olefins to C7 olefins of 0.5 to 2.5 and a research octane number (RON) of 89 or higher; and b) 40 vol % to 95 vol % of a conventional naphtha, the conventional naphtha having an olefins content of less than 13 vol % and an aromatics content of 10 vol % to 20 vol %, relative to a weight of the conventional naphtha, the conventional naphtha comprising an anti-knock index (AKI) of 85 to 93, to form a blended naphtha boiling range composition comprising an AKI of 87 or more and an olefins content of 5.0 vol % or more, relative to a weight of the blended naphtha boiling range composition.

[0096] All numerical values within the detailed description and the claims herein are modified by “about” or “approximately” the indicated value, and take into account experimental error and variations that would be expected by a person having ordinary skill in the art.

[0097] While the present invention has been described and illustrated by reference to particular embodiments, those of ordinary skill in the art will appreciate that the invention lends itself to variations not necessarily illustrated herein. For this reason, then, reference should be made solely to the appended claims for purposes of determining the true scope of the present invention.

Claims

1. An olefinic naphtha composition comprising 35 wt % to 80 wt % olefins and 6.0 wt % or less aromatics, the composition comprising a weight ratio of C8 olefins to C7 olefins of 0.5 to 2.5 and a research octane number (RON) of 89 or higher.

2. The olefinic naphtha composition of claim 1, wherein the composition further comprises 1.0 wt % to 10 wt % of n-paraffins.

3. The olefinic naphtha composition of claim 1, wherein the composition further comprises 1.0 wt % to 20 wt % of naphthenes.

4. The olefinic naphtha composition of claim 1, wherein the olefinic naphtha composition comprises a T90 distillation point of 150° C. or less.

5. The olefinic naphtha composition of claim 1, wherein the olefinic naphtha composition comprises 40 wt % to 55 wt % olefins.

6. The olefinic naphtha composition of claim 1, wherein the composition comprises a weight ratio of isoparaffins to n-paraffins of 2.5 to 7.5.

7. The olefinic naphtha composition of claim 1, wherein the olefinic naphtha composition comprises a lower heating value of 30.0 MJ / kg or higher.

8. A blended naphtha boiling range composition comprising:5.0 vol % to 50 vol % of an olefinic naphtha composition comprising 35 wt % to 80 wt % olefins and 6.0 wt % or less aromatics, relative to a weight of the olefinic naphtha composition, the olefinic naphtha composition comprising a weight ratio of C8 olefins to C7 olefins of 0.5 to 2.5 and a research octane number (RON) of 89 or higher; and40 vol % to 95 vol % of a conventional naphtha, the conventional naphtha having an olefins content of less than 13 vol % and an aromatics content of 10 vol % to 35 vol %, relative to a weight of the conventional naphtha, the conventional naphtha comprising an anti-knock index (AKI) of 85 to 93,wherein the blended naphtha boiling range composition comprises an AKI of 87 or more and an olefins content of 5.0 vol % or more, relative to a weight of the blended naphtha boiling range composition.

9. The blended naphtha boiling range composition of claim 8, wherein the blended naphtha boiling range composition comprises 18 wt % or less aromatics relative to a weight of the blended naphtha boiling range composition.

10. The blended naphtha boiling range composition of claim 8, wherein the conventional naphtha comprises 6.0 vol % or less of olefins.

11. The blended naphtha boiling range composition of claim 8, wherein the blended naphtha boiling range composition further comprises 10 wppm to 240 wppm of an antioxidant additive.

12. The blended naphtha boiling range composition of claim 8, wherein the olefinic naphtha composition comprises 1.0 wt % to 20 wt % of naphthenes relative to a weight of the olefinic naphtha composition.

13. The blended naphtha boiling range composition of claim 8, wherein the olefinic naphtha composition comprises 40 wt % to 55 wt % olefins.

14. The blended naphtha boiling range composition of claim 8, wherein the blended naphtha boiling range composition comprises a weight ratio of C8 olefins to C7 olefins of 0.5 to 2.5.

15. The blended naphtha boiling range composition of claim 8, wherein the blended naphtha boiling range composition comprises an olefins content of 10 wt % or more.

16. The blended naphtha boiling range composition of claim 8, wherein the olefinic naphtha composition comprises an AKI of 87 or higher.

17. The blended naphtha boiling range composition of claim 8, wherein the blended naphtha boiling range composition further comprises 1.0 vol % to 15 vol % of ethanol.

18. The blended naphtha boiling range composition of claim 8, wherein the AKI of the blended naphtha boiling range composition is lower than an AKI of the olefinic naphtha composition, or wherein a RON of the blended naphtha boiling range composition is lower than the RON of the olefinic naptha composition, or a combination thereof.

19. The blended naphtha boiling range composition of claim 8, wherein the olefinic naphtha composition comprises a T10 distillation point of 28° C. or more and a T90 distillation point of 210° C. or less.

20. The blended naphtha boiling range composition of claim 8, wherein the olefinic naphtha composition comprises a lower heating value of 30.0 MJ / kg or higher.

21. The blended naphtha boiling range composition of claim 8, wherein the conventional naphtha composition comprises 10 wt % to 24 wt % aromatics.

22. A method for forming a blended naphtha boiling range composition comprising:mixinga) 5.0 vol % to 50 vol % of an olefinic naphtha composition comprising 35 wt % to 80 wt % olefins and 6.0 wt % or less aromatics, relative to a weight of the olefinic naphtha composition, the olefinic naphtha composition comprising a weight ratio of C8 olefins to C7 olefins of 0.5 to 2.5 and a research octane number (RON) of 89 or higher; andb) 40 vol % to 95 vol % of a conventional naphtha, the conventional naphtha having an olefins content of less than 13 vol % and an aromatics content of 10 vol % to 20 vol %, relative to a weight of the conventional naphtha, the conventional naphtha comprising an anti-knock index (AKI) of 85 to 93,to form a blended naphtha boiling range composition comprising an AKI of 87 or more and an olefins content of 5.0 vol % or more, relative to a weight of the blended naphtha boiling range composition.

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