US20150112106A1

US20150112106A1 - Blending of dewaxed biofuels and synthesized paraffinic kerosines with mineral-based kero(jet) distillate cuts to provide on-spec jet fuels

Info

Publication number: US20150112106A1
Application number: US14/580,916
Authority: US
Inventors: Gregory P. Rockwell; Marc-Andre Poirier
Original assignee: ExxonMobil Research and Engineering Co
Current assignee: ExxonMobil Technology and Engineering Co
Priority date: 2012-12-28
Filing date: 2014-12-23
Publication date: 2015-04-23

Abstract

The present invention describes a method of making a jet fuel composition comprising: blending from about 3 vol % to about 30 vol % of a catalytically and/or thermally cracked blendstock into a non-cracked jet-boiling-range distillate to produce a jet-type blend with a smoke point less than 18 mm; and thereafter, blending from about 2 vol % to about 50 vol % of synthesized paraffinic kerosine (SPK) into the jet-type blend to produce a jet fuel with a smoke point of at least 18 mm.

Description

CROSS-REFERENCE TO RELATE APPLICATIONS

This application is a continuation-in-part of U.S application Ser. No. 14/141,618, filed on Dec. 27, 2013, which claims the benefit of U.S. application Ser. No. 61/746,835 filed on Dec. 28, 2012, both of which are incorporated by reference herein in its entirety.

FIELD OF THE INVENTION

This invention involves fit-for-purpose jet fuel compositions and methods for making them. In particular, mineral-based kerosene type fuels and/or off-spec jet fuels can be made to be on-spec by blending them with a deoxygenated and isomerized biofuel or with a synthesized paraffinic kerosine.

BACKGROUND OF THE INVENTION

Rising costs and threats of shortages and supply interruptions have recently highlighted the need for alternative fuel sources to mineral-based fuel products. In addition, availability of mineral-based fuel products having expected or desirable properties and/or product composition has been recently changing as well. In the past, a standard solution to changing specifications and/or fuel product availabilities was to treat (and/or treat more severely) existing fuel compositions to result in a fuel that could meet increasingly stringent specifications. However, with treatment methods for existing mineral-based fuels being expensive and/or unable to meet the volume demand, past approaches are becoming decreasingly desirable and/or successful.
Biofuels (renewable fuels) have particularly become a focus for alternative fuels/fuel blends, as finding mineral-based additives/blendstocks with the appropriate compositional and physical properties has also been getting increasingly difficult. There have been some publications on the subject of using renewable feedstocks in kero(jet) applications.
U.S. Patent Application Publication No. 2009/0158637 discloses a process for producing aviation fuel from renewable feedstocks. The feedstocks include plant oils and animal fats and oils. The process involves treating a renewable feedstock by hydrogenating and deoxygenating to provide n-paraffins having from about 8 to about 24 carbon atoms. At least some of the n-paraffins are isomerized to improve cold flow properties. At least a portion of the paraffins are selectively cracked to provide paraffins meeting specifications for different aviation fuels such as JP-8.
U.S. Patent Application Publication No. 2009/0088351 discloses a method for processing triglyceride-containing, biologically-derived oils to produce lubricants and transportation fuels. The method comprises converting triglycerides to free fatty acids and then separating the fatty acids by saturation type. Such separation by type enables the preparation of both lubricants and transportation fuels.
U.S. Patent Application Publication No. 2008/0244962 discloses a method for producing an isoparaffinic product useful as jet fuel from a renewable feedstock. The method also includes co-producing a jet fuel and a liquefied petroleum gas (LPG) fraction from a renewable feedstock. The method includes hydrotreating the renewable feedstock to produce a heavy hydrotreated stream that includes n-paraffins and hydroisomerizing the hydrotreating unit heavy fraction to produce a hydroisomerizing unit heavy fraction that includes isoparaffins. The method also includes recycling the hydroisomerizing unit heavy fraction through the hydroisomerization unit to produce an isoparaffinic product that may be fractionated into a jet fuel and an LPG fraction. The produced product is a jet fuel produced from a renewable feedstock having specified cold flow properties.
U.S. Patent Application Publication No. 2006/0229222 relates to methods for improving the low temperature storage and performance properties of fatty acids and their derivatives, as well as of composition containing them, by the use of stabilizers selected from branched chain fatty acids, cyclic fatty acids, and polyamides. Jet fuels and diesel are mentioned as blend components for fatty acid compositions.
U.S. Patent Application Publication No. 2008/0163542 discloses blends of petroleum based fuels with renewable fuels to enhance the low temperature operability of the blends. Various performance indices, such as the Cold Filter Plugging Point, the Low Temperature Flow Test, Pour Point, and Cloud Point, are taken as measures of the low temperature performance characteristics of fuels such as kerosene-type aviation fuels, e.g., JP-5, JP-8, Jet A, and Jet A-1. The bio-derived component in the blend is stated to be no more than 50% v/v in typical cases and more typically up to 35% v/v;
very low proportions down to 0.5% are mentioned but with no advantage shown for such blends.
U.S. Patent Application Publication No. 2010/0005706 discloses fuel oil compositions based on blends of renewable and petroleum fuels with additives to enhance the resistance to forming particulates during low temperature storage.
Other relevant references can include U.S. Patent Application Publication Nos. 2008/0052983, 2008/0092436, 2009/0013617, 2009/0229172, 2009/0229173, 2009/0162264, 2010/0000908, 2010/014535, 2011/0061290, 2011/0203253, 2011/0126449, and 2012/0152803; U.S. Pat. Nos. 3,573,198 and 7,928,273; PCT Publication No. WO 10/058580; the abstract by P. H. Steele et al., entitled “Comparison of hydroprocessed bio-oil gasoline, diesel and jet fuel fractions characteristics to ASTM standards for drop-in fuels”, in ACS National Meeting Book of Abstracts for the American Chemical Society Conference: 240th ACS National Meeting and Exposition, Aug. 22-26, 2010; and the abstract by Daniel Derr, entitled “Jet fuel from biologically-derived triacylglycerol oils”, in Preprints of Symposia—American Chemical Society, Division of Fuel Chemistry (2010), 55(2), 414.
There are few publications and/or little publicly available information regarding jet fuels/cuts, particularly mineral-based kero(jet) fuels/cuts, that are off-specification in one or more ways and possible blend components to tailor the properties of a resulting blend to be useful as a fit-for-purpose jet fuel composition. Highly dewaxed (isomerized) and deoxygenated paraffinic biofuels can be particularly useful as blendstocks for such off-specification kero(jet) fuels/cuts. Additionally or alternately, synthesized paraffinic kerosines can be particularly useful as blend components for enabling increased concentrations of cracked blendstocks in jet fuels and/or for off-specification jet fuels that contain higher concentrations of cracked components, such as low-smoke-point jet fuels containing heavy cat naphtha.

SUMMARY OF THE INVENTION

One aspect of the invention relates to a method of making a jet fuel composition comprising: blending from about 3 vol % to about 30 vol % of a catalytically and/or thermally cracked blendstock into a non-cracked jet-boiling-range distillate to produce a jet-type blend with a smoke point less than 18 mm; and thereafter, blending from about 2 vol % to about 50 vol % of synthesized paraffinic kerosine into the jet-type blend to produce a jet fuel with a smoke point of at least 18 mm. The specific concentrations of cracked blendstock and SPK employed can advantageously be chosen based on: a pre-determined relationship between smoke point and cracked blendstock concentration; a pre-determined relationship between smoke point and SPK concentration; and current refinery economics, such as the cost of
SPK and the differential between jet fuel and other refinery products that compete for cracked blendstocks (e.g., gasoline). In addition to smoke point, the blending of SPK may serve to improve other properties of the jet-type blend, such as by enabling JFTOT to be passed at or above ˜260° C., lowering naphthalenes to below ˜3.0 vol %, lowering aromatics to below ˜25 vol %, and/or lowering total sulfur to below ˜0.30 mass %.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 graphically shows the effect on jet-type blend smoke point of the combination of varying proportions of heavy cat naphtha (HCN) with non-cracked jet-boiling-range distillate.

FIG. 2 graphically shows the effect on jet fuel smoke point of the combination of varying proportions of hydrotreated vegetable oil (HVO) with jet-type blends.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The present invention can involve compositions useful for on-spec jet fuels and methods for making those compositions. Thus, one of the methods for making a jet fuel composition according to the invention can include: providing a mineral-based kero/jet-type distillate component that is in some way off-specification for jet fuel; providing a renewable component that has been treated to achieve a set of particular compositions and/or physical/bulk properties; and blending the components together to improve one or more measurable properties to thus achieve a fit-for-purpose (an on-spec) jet fuel composition.
The terms “mineral” and “mineral-based” are used herein to denote components or compositions that are naturally occurring and derived from non-renewable sources. Examples of such non-renewable resources can include petroleum oil/gas deposits, shale oil/gas deposits, natural gas deposits, coal deposits, and the like, and combinations thereof, including any hydrocarbon-laden deposits that can be mined/extracted from ground/underground sources. The term “cracked blendstock” is used herein to denote hydrocarbon that has been processed (e.g., at a refinery) by catalytic and/or thermal cracking in the substantial absence of externally added hydrogen, and can specifically include the products of such processes as fluid catalytic cracking and coking, inter alia. The term “non-cracked jet-boiling-range distillate” is used herein to denote hydrocarbon, derived from the distillation of crude oil, with a final boiling point below ˜300° C. that contains substantially no added cracked blendstock (e.g., no intentionally added cracked blendstock), but may contain components such as straight-run kerosene and hydrocrackate. The term “synthesized paraffinic kersosine” is used herein to denote hydrocarbon with a final boiling point below 300° C. that is derived from hydroprocessed liquids from a Fischer-Tropsch process and/or from hydroprocessed esters and fatty acids. Hydrotreated vegetable oil (HVO) is one non-limiting example of synthesized paraffinic kerosine (SPK).
There are many ways in which the mineral-based kero/jet-type distillate component according to a first aspect of the invention can be characterized. One convenient way is through its physico-chemical properties. For instance, the mineral-based kero/jet-type distillate component can advantageously have one or more of the following enumerated properties: an initial boiling point of at least about 100° C.; a T90 boiling point from about 260° C. to about 295° C.; a final boiling point from about 275° C. to about 300° C.; a freezing point from about −50° C. to about −20° C.; a smoke point from about 14 mm to about 19 mm; a naphthalene content from about 2.8 vol % to about 3.5 vol %; a JFTOT VTR rating failing the jet fuel specification; and a sulfur content from about 2000 wppm to about 3500 wppm. In some embodiments, the mineral-based kero/jet-type distillate component can advantageously have two or more of the enumerated properties, e.g., three or more, four or more, five or more, six or more, or all of the enumerated properties.
When approximating boiling point ranges of compositions, ASTM D86 can be used, although ASTM D2887 could alternately be used. Initial boiling point can be understood to represent the temperature at which the first material in a composition/component is observed to turn from liquid phase to vapor phase. Conversely, final boiling point can be understood to represent the temperature at which the last material in a composition/component is observed to turn from liquid phase to vapor phase. As a convention, the temperature at which approximately “x” percent of the composition/component has turned from liquid phase to vapor phase can be termed the “T[x] boiling point” according to ASTM D86. Thus, for example, the point at which −10% of a composition/component has turned from liquid phase to vapor phase is termed herein the T10 boiling point. The freezing point can be determined according to ASTM D4529. The smoke point can be determined according to ASTM D1322.
The naphthalene content can be determined according to ASTM D1840. The sulfur content can be measured according to at least one of the following standard test methods: ASTMs D1266, D2622, D4294, and D5453. JFTOT can be determined according to ASTM D3241 using a visual tuberator (VTR), in which passing ratings can be considered as 1, <2, 2, and <3, and in which failing ratings can be considered as 3, <4, 4, and peacock.
Additionally or alternatively, the mineral-based kero/jet-type distillate component can exhibit an ASTM D86 initial boiling point of at least about 100° C., e.g., at least about 105° C., at least about 110° C., at least about 115° C., at least about 120° C., at least about 125° C., at least about 130° C., at least about 135° C., at least about 140° C., at least about 145° C., at least about 150° C., from about 100° C. to about 160° C., from about 100° C. to about 150° C., from about 100° C. to about 140° C., from about 100° C. to about 130° C., from about 105° C. to about 160° C., from about 105° C. to about 150° C., from about 105° C. to about 140° C., from about 105° C. to about 130° C., from about 110° C. to about 160° C., from about 110° C. to about 150° C., from about 110° C. to about 140° C., from about 110° C. to about 130° C., from about 115° C. to about 160° C., from about 115° C. to about 150° C., from about 115° C. to about 140° C., from about 115° C. to about 130° C., from about 120° C. to about 160° C., from about 120° C. to about 150° C., from about 120° C. to about 140° C., from about 120° C. to about 130° C., from about 125° C. to about 160° C., from about 125° C. to about 150° C., or from about 125° C. to about 140° C.
Further additionally or alternatively, the mineral-based kero/jet-type distillate component can exhibit an ASTM D86 10% distillation point within the range from about 150° C. to about 200° C., for example from about 160° C. to about 180° C. Still further additionally or alternatively, the mineral-based kero/jet-type distillate component can exhibit an ASTM D86 90% distillation point within the range from about 250° C. to about 295° C., e.g., from about 250° C. to about 290° C., from about 250° C. to about 285° C., from about 250° C. to about 280° C., from about 260° C. to about 295° C., from about 260° C. to about 290° C., from about 260° C. to about 285° C., from about 260° C. to about 280° C., from about 270° C. to about 295° C., from about 270° C. to about 290° C., from about 270° C. to about 285° C., or from about 270° C. to about 280° C. Yet further additionally or alternatively, the mineral-based kero/jet-type distillate component can exhibit an ASTM D86 final boiling point less than about 300° C., e.g., less than about 298° C., less than about 296° C., less than about 295° C., from about 265° C. to about 300° C., from about 265° C. to about 295° C., from about 265° C. to about 290° C., from about 270° C. to about 300° C., from about 270° C. to about 295° C., from about 270° C. to about 290° C., from about 275° C. to about 300° C., from about 275° C. to about 295° C., from about 275° C. to about 290° C., from about 280° C. to about 300° C., from about 280° C. to about 295° C., from about 280° C. to about 290° C., from about 285° C. to about 300° C., from about 285° C. to about 295° C., from about 290° C. to about 300° C., or from about 295° C. to about 300° C.
In embodiments according to this aspect of the invention, the mineral-based kero/jet-type distillate component can exhibit a freezing point from about −50° C. to about −20° C., e.g., from about −50° C. to about −25° C., from about −50° C. to about −30° C., from about −50° C. to about −35° C., from about −50° C. to about −40° C., from about −45° C. to about −25° C., from about −45° C. to about −30° C., from about −45° C. to about −35° C., from about −45° C. to about −40° C., from about −40° C. to about −20° C., from about −40° C. to about −25° C., from about −40° C. to about −30° C., from about −35° C. to about −20° C., from about −35° C. to about −25° C., from about −38° C. to about −20° C., from about −38° C. to about −25° C., or from about −38° C. to about −30° C.
In embodiments according to this aspect of the invention, the mineral-based kero/jet-type distillate component can exhibit a smoke point from about 14 mm to about 19 mm, e.g., from about 14 mm to about 18 mm, from about 14 mm to about 17 mm, from about 14 mm to about 16 mm, from about 15 mm to about 19 mm, from about 15 mm to about 18 mm, from about 15 mm to about 17 mm, from about 16 mm to about 19 mm, from about 16 mm to about 18 mm, or from about 17 mm to about 19 mm.
In embodiments according to this aspect of the invention, the mineral-based kero/jet-type distillate component can exhibit a sulfur content from about 2000 wppm to about 3500 wppm, e.g., from about 2000 wppm to about 3400 wppm, from about 2000 wppm to about 3300 wppm, from about 2000 wppm to about 3200 wppm, from about 2000 wppm to about 3100 wppm, from about 2000 wppm to about 3000 wppm, from about 2000 wppm to about 2900 wppm, from about 2500 wppm to about 3500 wppm, from about 2500 wppm to about 3400 wppm, from about 2500 wppm to about 3300 wppm, from about 2500 wppm to about 3200 wppm, from about 2500 wppm to about 3100 wppm, from about 2500 wppm to about 3000 wppm, from about 2500 wppm to about 2900 wppm, from about 2700 wppm to about 3500 wppm, from about 2700 wppm to about 3400 wppm, from about 2700 wppm to about 3300 wppm, from about 2700 wppm to about 3200 wppm, from about 2700 wppm to about 3100 wppm, from about 2700 wppm to about 3000 wppm, from about 2700 wppm to about 2900 wppm, from about 2800 wppm to about 3500 wppm, from about 2800 wppm to about 3400 wppm, from about 2800 wppm to about 3300 wppm, from about 2800 wppm to about 3200 wppm, from about 2800 wppm to about 3100 wppm, from about 2800 wppm to about 3000 wppm, from about 2800 wppm to about 2900 wppm, from about 2900 wppm to about 3500 wppm, from about 2900 wppm to about 3400 wppm, from about 2900 wppm to about 3300 wppm, from about 2900 wppm to about 3200 wppm, from about 2900 wppm to about 3100 wppm, from about 2900 wppm to about 3000 wppm, from about 3000 wppm to about 3500 wppm, from about 3000 wppm to about 3400 wppm, from about 3000 wppm to about 3300 wppm, from about 3000 wppm to about 3200 wppm, from about 3000 wppm to about 3100 wppm, from about 3100 wppm to about 3500 wppm, from about 3100 wppm to about 3400 wppm, from about 3100 wppm to about 3300 wppm, from about 3100 wppm to about 3200 wppm, from about 3200 wppm to about 3500 wppm, from about 3200 wppm to about 3400 wppm, from about 3200 wppm to about 3300 wppm, from about 3300 wppm to about 3500 wppm, from about 3300 wppm to about 3400 wppm, or from about 3400 wppm to about 3500 wppm.
In some embodiments, the mineral-based kero/jet-type distillate component can optionally exhibit an olefin (unsaturated double bond) content of at least about 0.7% by weight, e.g., at least about 0.8% by weight, at least about 0.9% by weight, at least about 1.0% by weight, at least about 1.1% by weight, at least about 1.2% by weight, at least about 1.3% by weight, or at least about 1.4% by weight.
Advantageously, the step of providing a renewable component that has been treated to achieve a set of particular compositions and/or physical/bulk properties can be satisfied by providing a deoxygenated and dewaxed renewable component derived from triglycerides and/or fatty acids. The deoxygenated and dewaxed renewable component can exhibit an isoparaffin to normal paraffin ratio from about 2:1 to about 6:1, e.g., from about 2:1 to about 5:1, from about 2:1 to about 4:1, from about 2:1 to about 3:1, from about 3:1 to about 6:1, from about 3:1 to about 5:1, from about 3:1 to about 4:1, from about 4:1 to about 6:1 from about 4:1 to about 5:1, or from about 5:1 to about 6:1. Additionally or alternatively, the deoxygenated and dewaxed renewable component can exhibit an aromatics content less than about 5 vol %, e.g., less than about 4 vol %, less than about 3 vol %, less than about 2 vol %, less than about 1 vol %, less than about 0.7 vol %, less than about 0.5 vol %, less than about 0.3 vol %, less than about 0.1 vol %, or less than about 0.05 vol %. Further additionally or alternately, the deoxygenated and dewaxed renewable component can exhibit an olefin (unsaturated double bond) content less than about 1.5% by weight, e.g., less than about 1.2% by weight, less than about 1% by weight, less than about 0.8% by weight, less than about 0.7% by weight, less than about 0.6% by weight, less than about 0.5% by weight, less than about 0.4% by weight, less than about 0.3% by weight, less than about 0.2% by weight, or less than about 0.1% by weight.
In additional or alternative embodiments, the step of providing a renewable component that has been treated to achieve a set of particular compositions and/or physical/bulk properties can be satisfied by appropriately treating a raw renewable oil/fat composition to achieve the desired characteristics.
The raw renewable oil/fat composition can advantageously be derived predominantly (more than 50% by weight, e.g., more than 60% by weight, more than 70% by weight, more than 80% by weight, more than 90% by weight, more than 95% by weight, or more than 99% by weight) or completely from triglycerides and/or fatty acid components. Triglycerides, as used herein, can include glycerol transesterified with three fatty acids, which are carboxylic acid heads attached to hydrocarbon acyl tails/chains. However, in some embodiments, triglycerides can include mono- and di-substituted versions of glycerol, as well as tri-substituted glycerol. It should be understood that fatty acids are described in terms of how many carbons on their molecule, which is one more than the number of carbons in their acyl chains (as the carboxylic acid carbon is not counted in the acyl chain but is still part of the molecule). Thus, a fatty acid having 14 carbons has an acyl chain with 13 carbons attached to a carboxylic acid (or ion or salt). Further, glycerides can be defined in the same manner—where a triglyceride has three chains of 14 carbons attached via an ester linkage to glycerol, the triglyceride can be said to have acyl chains with 13 carbons as well as the ester carbon (which would be a carboxylic acid, or ion or salt, carbon, if disconnected from the glycerol).
In preferred embodiments, at least 80% of the acyl chains (on both the triglycerides and fatty acids/ions/salts, if both are present) can have from 7 to 17 carbons, e.g., from 7 to 15 carbons, from 7 to 13 carbons, from 7 to 11 carbons, from 9 to 17 carbons, from 9 to 15 carbons, from 9 to 13 carbons, or from 9 to 11 carbons. Additionally or alternatively, at least 85% of the acyl chains can have from 7 to 17 carbons, e.g., from 7 to 15 carbons, from 7 to 13 carbons, from 7 to 11 carbons, from 9 to 17 carbons, from 9 to 15 carbons, from 9 to 13 carbons, or from 9 to 11 carbons.
Alternatively, at least 90% of the acyl chains can have from 7 to 17 carbons, e.g., from 7 to 15 carbons, from 7 to 13 carbons, from 7 to 11 carbons, from 9 to 17 carbons, from 9 to 15 carbons, from 9 to 13 carbons, or from 9 to 11 carbons. Further additionally or alternatively, at least 95% of the acyl chains can have from 7 to 17 carbons, e.g., from 7 to 15 carbons, from 7 to 13 carbons, from 7 to 11 carbons, from 9 to 17 carbons, from 9 to 15 carbons, from 9 to 13 carbons, or from 9 to 11 carbons. Still further additionally or alternatively, at least 98% of the acyl chains can have from 7 to 17 carbons, e.g., from 7 to 15 carbons, from 7 to 13 carbons, from 7 to 11 carbons, from 9 to 17 carbons, from 9 to 15 carbons, from 9 to 13 carbons, or from 9 to 11 carbons. Yet further additionally or alternatively, at least 99% (and/or substantially all) of the acyl chains can have from 7 to 17 carbons, e.g., from 7 to 15 carbons, from 7 to 13 carbons, from 7 to 11 carbons, from 9 to 17 carbons, from 9 to 15 carbons, from 9 to 13 carbons, or from 9 to 11 carbons.
Once provided, the raw renewable fat/oil composition can be catalytically deoxygenated and dewaxed. These steps can be done simultaneously or in order (deoxygenation first, then dewaxing). It should be understood that, although the steps are strictly termed “deoxygenation” and “dewaxing” steps herein, other catalytic reactions may take place during them. For example, it can be common for unsaturated hydrocarbon bonds (e.g., double/olefinic bonds, triple bonds, conjugated/aromatic bonds, etc.) to become saturated during the deoxygenation reaction and/or during the dewaxing reaction (e.g., due to the presence of hydrogen gas in both and the multi-purpose catalytic capability of most deoxygenation and/or dewaxing/isomerization catalysts).
When deoxygenation and dewaxing steps are accomplished simultaneously, the catalytic processes may be done in a single zone of a reactor where a deoxygenation catalyst is intimately mixed with a dewaxing catalyst, or they may be done using a single deoxygenation/dewaxing catalyst capable of catalyzing both reactions.
The dewaxing catalyst can usually be the same whether used in addition to a separate deoxygenation catalyst or as a single/combination catalyst. Nevertheless, when separate deoxygenation and dewaxing catalysts are used, the deoxygenation catalyst can include any catalyst capable of catalytically hydrotreating a hydrocarbon composition in the presence of a H₂-containing gas. Examples of such separate deoxygenation catalysts can include, but are not necessarily limited to, bulk/massive nickel, oxides of one or more metals of Groups 6 and 8-12 of the Periodic Table of Elements (e.g., iron, cobalt, nickel, chromium, molybdenum, tungsten, zinc copper, and combinations thereof), an active hydrogenation metal (e.g., selected from Groups 8-10 of the Periodic Table of Elements, such as iron, cobalt, nickel, palladium, platinum, ruthenium, and the like, and combinations thereof) supported on an oxide (e.g., alumina, silica, titania, magnesia, thoria, zirconia, yttria, ceria, and combinations thereof, including aluminosilicates, aluminophosphates, and/or silicoaluminophosphates), and the like, and combinations thereof In some cases, partially (or almost completely) spent hydrotreating catalysts (e.g., CoMo, NiMo, CoW, NiW, CoMoW, NiMoW, etc.) can still be used to catalytically deoxygenate. Additionally or alternately, water gas shift catalysts (e.g., iron oxides such as Fe₃O₄) that would not have enough activity for hydrotreating sulfur- and/or nitrogen-containing feeds can be useful in catalytic deoxygenation reactions.
In such situations where deoxygenation is done in a separate zone and/or reactor, the deoxygenation conditions can include: an LHSV of the input stream from about 0.1 hr⁻ to about 20 hr⁻¹, e.g., from about 0.5 hr⁻¹to about 1.5 hr⁻¹or from about 2 hr⁻¹to about 20 hr⁻¹; a weight average bed temperature or an estimated internal temperature (WABT or EIT, abbreviated herein as “temperature”) from about 550° F. to about 700° F. (about 288° C. to about 371° C.), e.g., from about 575° F. to about 675° F. (about 302° C. to about 357° C.), from about 550° F. to about 625° F. (about 288° C. to about 329° C.), from about 550° F. to about 600° F. (about 288° C. to about 315° C.), or from about 600° F. to about 650° F. (about 315° C. to about 343° C.); a reactor pressure from about 50 psig (about 340 kPag) to about 600 psig (about 4.1 MPag), for example from about 100 psig (about 690 kPag) to about 400 psig (about 2.8 MPag), from about 50 psig (about 340 kPag) to about 300 psig (about 2.1 MPag), or from about 150 psig (about 1.0 MPag) to about 350 psig (about 2.0 MPag); and a hydrogen treat gas rate from about 500 scf/bbl to about 5000 scf/bbl (about 85 Nm³/m³to about 850 Nm³/m³), e.g., from about 750 scf/bbl to about 3000 scf/bbl (about 130 Nm³/m³to about 510 Nm³/m³), from about 750 scf/bbl to about 2500 scf/bbl (about 130 Nm³/m³to about 470 Nm³/m³), from about 900 scf/bbl to about 2500 scf/bbl (about 150 Nm³/m³to about 470 Nm³/m³), or from about 1000 scf/bbl to about 3000 scf/bbl (about 170 Nm³/m³to about 510 Nm³/m³).
In a preferred embodiment, the deoxygenation step, whether simultaneous with or initial to the dewaxing step, can be conducted to achieve an oxygen content of less than 100 wppm (e.g., less than 75 wppm, less than 50 wppm, less than 40 wppm, less than 30 wppm, less than 25 wppm, less than 20 wppm, less than 15 wppm, less than 10 wppm, or less than 5 wppm) and/or to reduce the oxygen content by at least 95% by weight (e.g., at least 97% by weight, at least 98% by weight, at least 99% by weight, at least 99.5% by weight, at least 99.9% by weight, at least 99.95% by weight, or at least 99.99% by weight).
Dewaxing processes can advantageously result in reduction/removal of longer-chain saturated hydrocarbons, which are commonly called waxes. Dewaxing can take two forms—a hydrocracking form, where such longer-chain saturated hydrocarbon wax molecules are broken, or cracked, to form shorter-chain saturated hydrocarbons that no longer exhibit the crystallization, for example, of waxes; and an isomerization form, where longer-chain saturated hydrocarbon wax molecules are rearranged (isomerized) to yield roughly similarly sized hydrocarbon chains that have hydrocarbon branches, which hydrocarbon branches thus disrupt the crystallization that waxes would otherwise experience. In this aspect of the invention, it can be preferred to utilize a dewaxing catalyst (and thus a dewaxing process) that can dewax mostly (e.g., as much as possible or almost completely) via isomerization mechanisms and sparingly (e.g., as little as possible or almost not at all) via cracking mechanisms. Particularly in such preferred embodiments, this can enable the use of the raw renewable component oils whose molecules exhibit relatively lower carbon numbers (lack of cracking means smaller molecules can be used without the product having too low a carbon number to be useful in the desired application). In alternate embodiments, where significant dewaxing via cracking mechanisms is catalyzed, the raw renewable component oils containing relatively higher carbon numbers may need to be used.
Thus, in one embodiment, the catalyst itself and/or the catalyst support material used in the isomerization step of this aspect of the invention can have an alpha value of less than 100, e.g., less than 75, less than 60, less than 50, less than 40, less than 30, or less than 20. The alpha value is an approximate indication of the catalytic cracking activity of the catalyst compared to a standard catalyst. The alpha test can give the relative rate constant (rate of normal hexane conversion per volume of catalyst per unit time) of the test catalyst relative to the standard catalyst which is taken as an alpha of 1 (Rate Constant=0.016 sec⁻¹). The alpha test is described in U.S. Pat. No. 3,354,078 and in J. Catalysis, 4, 527 (1965); 6, 278 (1966); and 61, 395 (1980), to which reference is made for a description of the test. The experimental conditions of the test used to determine the alpha values referred to in this specification include a constant temperature of 538° C. and a variable flow rate as described in detail in J. Catalysis, 61, 395 (1980).
Additionally or alternatively, the dewaxing catalyst support materials can include zeolitic supports exhibiting a 1-dimensional 10-ring pore structure. Further additionally or alternatively, the dewaxing catalyst support materials can include, but are not limited to, zeolite beta, zeolite Y, ultrastable zeolite Y, dealuminized zeolite Y, ZBM-30, ZSM-22, ZSM-23, ZSM-35, ZSM-48, SAPO-11, SAPO-5, MeAPO-11, MeAPO-5, MCM-41, MCM-48, and combinations and intergrowths thereof.
Catalysts useful in the dewaxing (isomerization) step according to this aspect of the invention can also contain one or more hydrogenation metals, which can be one or more noble metals, one or more non-noble metals, or a combination thereof.
Suitable noble metals include noble metals from Groups 8-10 of the Periodic Table of Elements, such as platinum and other members of the platinum group, such as iridium, palladium, ruthenium, rhodium, and combinations thereof Suitable non-noble metals include those of Groups 6 and 8-10 of the Periodic Table, such as chromium, molybdenum, tungsten, cobalt, nickel, and combinations thereof (including cobalt-molybdenum, nickel-tungsten, nickel-molybdenum, cobalt-nickel-molybdenum, nickel-molybdenum-tungsten, cobalt-molybdenum-tungsten, and cobalt-nickel-tungsten). The hydrogenation metal(s) may be present in a (collective) amount from about 0.3% to about 25%, based on the weight of the total dewaxing catalyst composition (e.g., for noble metals, from about 0.3 wt % to about 2.0 wt % or from about 0.5 wt % to about 1.5 wt %; for non-noble metals, typically at least one Group 6 metal is combined with at least one metal from Groups 8-10, such that the combination of metals can be from about 3 wt % to about 25 wt % or from about 5 wt % to about 20 wt %).
The metal can be incorporated into the catalyst by any suitable method or combination of methods, such as by impregnation or ion exchange into the zeolite. The metal can be incorporated in the form of a cationic, anionic, or neutral complex. Cationic complexes of the type Pt(NH₃)₄ ⁺⁺ can be used for exchanging metals onto the zeolite. Anionic complexes such as the molybdate or metatungstate ions can also be useful for impregnating metals into the catalysts.
The deoxygenation and/or dewaxing catalyst(s), in some embodiments, can include a binder (or matrix) material. Binder materials, when present, can preferably comprise or be metal oxides. Non-limiting examples of metal oxide binders can include, but are not limited to, alumina, silica-alumina, silica-magnesia, silica-zironcia, silica-thoria, silica-berylia, silica-titania, as well as ternary compositions such as silica-alumina-thoria, silica-alumina-zirconia, silica-alumina-magnesia, and silica-magnesia-zirconia, and the like, and combinations thereof When binders are present, the catalyst material can be formed into a useable shape by methods such as extrusion and/or tabletting.
The dewaxing (isomerization) reaction can be carried out in the presence of an Hz-containing gas under conditions of elevated temperature and pressure, which, for relatively severe isomerization in order to obtain relatively highly isomerized renewable product, can be particularly elevated (as well as using particular types of catalyst(s) in tandem therewith). If conducted simultaneously with the deoxygenation step and/or if dewaxing and deoxygenation are conducted in separate zones of a single reactor, the conditions in the dewaxing step can be substantially the same as in the deoxygenation step (or vice versa).
Conditions under which the isomerization process of this aspect of the invention can be carried out can include: an LHSV of the input stream from about 0.1 hr⁻¹to about 20 hr⁻¹, e.g., from about 0.5 hr⁻¹to about 1.5 hr⁻¹or from about 2 hr⁻¹to about 20 hr⁻¹; a weight average bed temperature or an estimated internal temperature (WABT or EIT, abbreviated herein as “temperature”) from about 600° F. to about 750° F. (about 315° C. to about 399° C.), e.g., from about 600° F. to about 700° F. (about 315° C. to about 371° C.), from about 600° F. to about 675° F. (about 315° C. to about 357° C.), from about 600° F. to about 650° F. (about 315° C. to about 343° C.), from about 625° F. to about 750° F. (about 329° C. to about 399° C.), from about 625° F. to about 700° F. (about 329° C. to about 371° C.), from about 625° F. to about 675° F. (about 329° C. to about 357° C.), from about 650° F. to about 750° F. (about 343° C. to about 399° C.), or from about 650° F. to about 700° F. (about 343° C. to about 371° C.); a hydrogen partial pressure from 1.7 atm to 204 atm (25 psia to 3000 psia, or 170 kPaa to 20.7 MPaa), for example 6.8 atm to 170 atm (100 psia to 2500 psia, or 1.4 MPaa to 17.3 MPaa); and a hydrogen treat gas rate from about 500 scf/bbl to about 5000 scf/bbl (about 85 Nm³/m³to about 850 Nm³/m³), e.g., from about 750 scf/bbl to about 3000 scf/bbl (about 130 Nm³/m³to about 510 Nm³/m³), from about 750 scf/bbl to about 2500 scf/bbl (about 130 Nm³/m³to about 470 Nm³/m³), from about 900 scf/bbl to about 2500 scf/bbl (about 150 Nm³/m³to about 470 Nm³/m³), or from about 1000 scf/bbl to about 3000 scf/bbl (about 170 Nm³/m³to about 510 Nm³/m³).
The H₂-containing gas introduced into both the deoxygenation and dewaxing (isomerization) reactors/zones can preferably contain more than 50 vol % hydrogen, e.g., at least about 75 vol %, at least about 80 vol %, at least about 85 vol %, at least about 90 vol %, or at least about 95 vol %.
Generally, the raw renewable oil/fat compositions/components for deoxygenation and dewaxing can include vegetable fats/oils, animal fats/oils, fish oils, oils/biomass extracted from fungus/bacteria, and algae lipids/oils, as well as separated portions of such materials. Examples of vegetable oils that can be used in accordance with this aspect of the invention include, but are not limited to rapeseed (canola) oil, soybean oil, coconut oil, sunflower oil, palm oil, palm kernel oil, peanut oil, linseed oil, tall oil, corn oil, castor oil, jatropha oil, jojoba oil, olive oil, flaxseed oil, camelina oil, safflower oil, cuphera oil, babassu oil, tallow oil, and rice bran oil. In the processes of this aspect of the invention, coconut, palm, palm kernel, cuphera, and babassu oils can be preferred, particularly in circumstances where the dewaxing process is desired to predominantly cause isomerization and to cause minimal cracking (e.g., because their raw product contains relatively shorter carbon number chains than many other such oils).
Algal sources for algae oils can include, but are not limited to, unicellular and multicellular algae. Examples of such algae can include a rhodophyte, chlorophyte, heterokontophyte, tribophyte, glaucophyte, chlorarachniophyte, euglenoid, haptophyte, cryptomonad, dinoflagellum, phytoplankton, and the like, and combinations thereof In one embodiment, algae can be of the classes Chlorophyceae and/or Haptophyta. Specific species can include, but are not limited to, Neochloris oleoabundans, Scenedesmus dimorphus, Euglena gracilis, Phaeodactylum tricornutum, Pleurochrysis carterae, Prymnesium parvum, Tetraselmis chui, and Chlamydomonas reinhardtii. Additional or alternate algal sources can include one or more microalgae of the Achnanthes, Amphiprora, Amphora, Ankistrodesmus, Asteromonas, Boekelovia, Borodinella, Botryococcus, Bracteococcus, Chaetoceros, Carteria, Chlamydomonas, Chlorococcum, Chlorogonium, Chlorella, Chroomonas, Chrysosphaera, Cricosphaera, Crypthecodinium, Cryptomonas, Cyclotella, Dunaliella, Ellipsoidon, Emiliania, Eremosphaera, Ernodesmius, Euglena, Franceia, Fragilaria, Gloeothamnion, Haematococcus, Halocafeteria, Hymenomonas, Isochrysis, Lepocinclis, Micractinium, Monoraphidium, Nannochloris, Nannochloropsis, Navicula, Neochloris, Nephrochloris, Nephroselmis, Nitzschia, Ochromonas, Oedogonium, Oocystis, Ostreococcus, Pavlova, Parachlorella, Pascheria, Phaeodactylum, Phagus, Pichochlorum, Pseudoneochloris, Pseudostaurastrum, Platymonas, Pleurochrysis, Pleurococcus, Prototheca, Pseudochlorella, Pyramimonas, Pyrobotrys, Scenedesmus, Schizochlamydella, Skeletonema, Spyrogyra, Stichococcus, Tetrachlorella, Tetraselmis, Thalassiosira, Tribonema, Vaucheria, Viridiella, and Vo/vox species, and/or one or more cyanobacteria of the Agmenellum, Anabaena, Anabaenopsis, Anacystis, Aphanizomenon, Arthrospira, Asterocapsa, Borzia, Calothrix, Chamaesiphon, Chlorogloeopsis, Chroococcidiopsis, Chroococcus, Crinalium, Cyanobacterium, Cyanobium, Cyanocystis, Cyanospira, Cyanothece, Cylindrospermopsis, Cylindrospermum, Dactylococcopsis, Dermocarpella, Fischerella, Fremyella, Geitleria, Geitlerinema, Gloeobacter, Gloeocapsa, Gloeothece, Halospirulina, Iyengariella, Leptolyngbya, Limnothrix, Lyngbya, Microcoleus, Microcystis, Myxosarcina, Nodularia, Nostoc, Nostochopsis, Oscillatoria, Phormidium, Planktothrix, Pleurocapsa, Prochlorococcus, Prochloron, Prochlorothrix, Pseudanabaena, Rivularia, Schizothrix, Scytonema, Spirulina, Stanieria, Starria, Stigonema, Symploca, Synechococcus, Synechocystis, Tolypothrix, Trichodesmium, Tychonema, and Xenococcus species.
In a preferred embodiment, the dewaxing step, whether simultaneous with or subsequent to the deoxygenation step, can be conducted under conditions sufficient to achieve an isoparaffin to normal paraffin ratio from about 2:1 to about 6:1 (e.g., from about 2:1 to about 5:1, from about 2:1 to about 4:1, from about 2:1 to about 3:1, from about 3:1 to about 6:1, from about 3:1 to about 5:1, from about 3:1 to about 4:1, from about 4:1 to about 6:1 from about 4:1 to about 5:1, or from about 5:1 to about 6:1) and/or an aromatics content less than about 10 vol % (e.g., less than about 5 vol %, less than about 4 vol %, less than about 3 vol %, less than about 2 vol %, less than about 1 vol %, less than about 0.5 vol %, less than about 0.3 vol %, or less than about 0.1 vol %).
Either taking a renewable component that has been provided to have the requisite deoxygenation and isomerization or having conducted the requisite reactions to obtain the renewable product, from about 3 vol % to about 25 vol % (e.g., from about 5 vol % to about 20 vol % or from about 10 vol % to about 20 vol %) of the renewable component/product can be blended with from about 75 vol % to about 97 vol % (e.g., from about 80 vol % to about 95 vol % or from about 80 vol % to about 90 vol %) of the mineral-based distillate component to form an on-spec jet fuel composition.
The on-spec jet fuel composition can advantageously have one or more of the following enumerated properties: a final boiling point of at most 300° C. or at least 7° C. below the final boiling point of the mineral-based distillate component alone; a freezing point of at most −40° C. or at least 4° C. less than the freezing point of the mineral-based distillate component alone; a smoke point of at least 18 mm or at least 2mm more than the smoke point of the mineral-based distillate component alone; a naphthalene content of at most 3.0 vol % or at least 0.3 vol % lower than the naphthalene content of the mineral-based distillate component alone; a JFTOT VTR rating passing the jet fuel specification; and a sulfur content of at most 3000 wppm or at least 150 wppm less than the sulfur content of the mineral-based distillate component alone. In some embodiments, the on-spec jet fuel composition/blend product can advantageously have two or more of the enumerated properties, e.g., three or more, four or more, five or more, or all of the enumerated properties.
Another aspect of the invention relates to a method of making a jet fuel composition comprising: blending a catalytically and/or thermally cracked blendstock with a non-cracked jet-boiling-range distillate to produce a jet-type blend with a smoke point less than 18 mm; and thereafter, blending synthesized paraffinic kerosine (SPK) with the jet-type blend to produce a jet fuel with a smoke point of at least 18 mm. The specific concentrations of cracked blendstock and SPK employed can advantageously be chosen based on: a pre-determined relationship between smoke point and cracked blendstock concentration; a pre-determined relationship between smoke point and SPK concentration; and current refinery economics, such as the cost of SPK and the differential between jet fuel and other refinery products that compete for cracked blendstocks (e.g., gasoline). Typical blending concentrations can be in the range of about 3-30 vol % for cracked blendstock into non-cracked jet-boiling-range distillate and about 2-50 vol % for SPK into the jet-type blend. In addition to smoke point, the blending of SPK may optionally serve to improve one or more other properties of the jet-type blend, such as by enabling JFTOT to be passed at or above ˜260° C., lowering naphthalenes to below ˜3.0 vol %, lowering aromatics to below ˜25 vol %, and lowering total sulfur to below ˜0.30 mass %.
One objective of this aspect of the invention can be to enable the maximization of catalytically or thermally cracked blendstocks in jet fuels. Such cracked streams at refineries can often be unsuitable in jet fuels due to their negative impact on properties such as smoke point and thermal stability (e.g., impact on JFTOT pass/fail). As a result, they are often blended with lower-margin products, such as gasoline. With a method to counter the negative impacts of cracked blendstocks, it may be possible to substantially raise the cracked blendstock content of jet fuels, enabling an increase in the volumetric rate of jet fuel manufacturing. Such an increase in rate can be beneficially used at refineries to increase the volume of jet fuel manufactured and/or to spend less run time on jet fuel manufacturing, enabling increased volumes of other higher-margin products that compete for refinery resources with jet fuel (e.g., diesel). This aspect of the invention may additionally or alternately assist refiners in meeting renewable requirements in their fuels by improving the economics of blending renewable SPKs, such as hydrotreated vegetable oil (HVO).
Due to the tight balance characteristic of refinery operations subject to supply demands, raising the cracked blendstock content of jet fuels can have an inherent risk of producing off-spec product, which can create supply dilemmas
Therefore, cracked blendstocks can often be used only in modest concentrations (e.g., less than 3 vol %) in jet fuels, sometimes being avoided altogether. Consequently, substantial “giveaway” can be an attribute of jet fuels, meaning that the properties of these fuels can be needlessly far above specifications, at the refinery's loss. This aspect of the invention, therefore, can enable aggressive maximization of the cracked blendstock content in jet fuels by providing a method for countering specification failures, particularly smoke point, encountered during cracked blendstock addition. While this aspect of the invention may be particularly beneficial for jet fuels, it can additionally or alternately be applied in a similar manner to other fuels meeting a smoke-point specification, for example, kerosene fuel oils.
As refineries can generally be poorly suited to trial-and-error approaches, this aspect of the invention can advantageously be employed by establishing relationships/correlations for jet fuels at the refinery between smoke point and concentration of cracked blendstocks and between smoke point and concentration of SPK components. These relationships could, for example, be based on a combination of pilot runs at the refinery and lab-based testing. Their importance in this aspect of the invention can be: to enable efficient manufacturing of on-spec jet fuels with maximum cracked blendstocks, for example, by enabling the timely release of products by minimizing re-blending and retesting; and/or to enable selection of the most economical balance between cracked blendstocks and SPK to yield on-spec jet fuels, for example, by enabling assessment of the costs involved in various cracked blendstock/SPK formulations for on-spec jet fuels. In analyzing these correlations, it can often be advantageous to utilize the latest smoke-point measurement technologies, such as the automated procedure recently added to ASTM D1322. This automated procedure can have considerably less error than the traditional manual procedure, which can improve the utility of the correlations. Ideally, smoke-point measurement for quality assurance at the refinery could also be based on such an automated procedure.
While this aspect of the invention can be focused on remedying failures of smoke-point specifications resulting from blending cracked blendstocks into jet fuels, it should be understood that other specification failures may additionally or alternately be remedied in the process. Due to its sources and processing, SPK can typically exhibit one, some, or all of relatively high smoke point, relatively high thermal stability, relatively low sulfur, relatively low naphthalenes, and relatively low aromatics; therefore, SPK can improve these properties when added to jet fuel compositions as a blend component. Cracked blendstocks, conversely, are generally rich in aromatic and other unsaturated molecules that tend to decrease smoke point and thermal stability, while increasing naphthalenes and aromatics contents. The use of cracked blendstocks may therefore cause or worsen specification failures beyond smoke point, when blended with non-cracked jet-boiling-range distillates. SPK, however, can reasonably be expected to remedy these failures while improving smoke point, as smoke point can be especially sensitive to cracked blendstocks. Typically in this aspect of the invention,
SPK can serve to improve jet fuel quality, whereas cracked blendstocks are typically added for economy. Nevertheless, cracked blendstocks may beneficially lower the freeze point of jet fuels, potentially providing an offset to the tendency of SPK to raise the freeze point.
Any cracked blendstock added to non-cracked jet-boiling-range distillate in this aspect of the invention can typically have a final boiling point below 300° C. The non-cracked jet-boiling-range distillate may meet or fail jet fuel specifications prior to cracked blendstock addition (e.g., smoke point may be in the range of about 14 mm to about 27 mm and/or JFTOT may be pass or fail). Non-cracked jet-boiling-range distillates can often be treated to reduce sulfur and polar molecules (e.g., hydrotreating, clay treating), and blending of cracked blendstock may occur before the non-cracked jet-boiling-range distillate is treated, in which case both components can be treated together, or after treatment of the non-cracked jet-boiling-range distillate, in which case the cracked blendstock may be treated separately in advance of blending (or both). In any scenario, treatment of the cracked blendstock may improve its quality as a blend component for jet fuels, enabling higher concentrations to be used. To resolve potential ambiguity, references herein to properties of the jet-type blend (e.g., smoke point less than 18 mm) apply to after any treating has been carried out on the jet-type blend or its components.
SPK can be blended with the jet-type blend in a subsequent step, advantageously guided by a pre-determined relationship between smoke point and SPK concentration. To facilitate this blending step, testing may be carried out on the jet-type blend prior to SPK addition. The SPK used can typically meet common fit-for-purpose specifications for synthetic blending components for jet fuel, such as those described in ASTM D7566. In the case of SPK derived from hydroprocessed esters and/or fatty acids, sources of esters/fatty acids can include, but need not be limited to, vegetable oils, fats, yellow grease, fatty-acid alkyl esters (such as FAMEs and/or FAEEs), microorganisms (e.g., algae, bacteria, and/or fungi), and the like, and combinations thereof In the case of SPK derived from hydroprocessed liquids from a Fischer-Tropsch process, the synthesis gas in the Fischer-Tropsch process could be derived from carbon sources such as biomass, natural gas, coal, or the like, or a combination thereof In the context of SPK, “hydroprocessed” means processed by reacting organic compounds with hydrogen in the presence of a catalyst to remove heteroatoms (e.g., sulfur, oxygen, nitrogen), to saturate chemical bonds, and/or to otherwise modify the structure of molecules (e.g., isomerize molecules).

EXAMPLE

The cracked blendstock heavy cat naphtha (HCN) was produced during fluid catalytic cracking and had a boiling-point range falling within ˜50° C. to ˜250° C. A combination of plant-scale and lab-scale tests provided data for the relationship between smoke point and vol % HCN in non-cracked jet-boiling-range distillate shown in FIG. 1, which was based on two sets of data (squares and diamonds) with one outlier excluded (unfilled diamond). This relationship indicated that, for every surplus millimeter of smoke point, approximately 3 vol % of HCN can be added to the non-cracked jet-boiling-range distillate.
Assuming the refinery runs close to the smoke-point specification of 18 mm for its jet-type blends, it can be unable to capture a benefit. A relationship between smoke point and volume percent hydrotreated vegetable oil (HVO), however, was generated for a jet fuel containing ˜8 vol % HCN using the automated smoke-point measurement procedure. This relationship, shown in FIG. 2, indicated that the addition of ˜10 vol % HVO to a jet-type blend increased smoke point by ˜1 mm. Therefore, by blending ˜10 vol % of HVO into its jet-type blends, a refinery may be able to make on-spec jet fuel, capture the benefit of increasing HCN in its jet fuel by ˜3 vol %, and simultaneously increase its overall use of renewables. While the decision to take advantage of this opportunity in an actual refinery could depend on factors such as the current cost of HVO, the requirements of regulations mandating the use of renewables, and the margin of distillates versus gasoline, the invention can provide the flexibility to take advantage of the opportunity when conditions are favorable.
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 enforceable scope of the present invention.

Claims

What is claimed is:

1. A method of making a jet fuel comprising:

blending from about 3 vol % to about 30 vol % of a catalytically and/or thermally cracked blendstock into a non-cracked jet-boiling-range distillate to produce a jet-type blend with a smoke point less than 18 mm; and

thereafter, blending from about 2 vol % to about 50 vol % of synthesized paraffinic kerosine into the jet-type blend to produce a jet fuel with a smoke point of at least 18 mm.

2. The method according to claim 1, wherein the blending of synthesized paraffinic kerosine into the jet-type blend achieves at least one of the following for the resulting jet fuel: a JFTOT pass at or above about 260° C.; a naphthalenes content below about 3.0 vol %, an aromatics content below about 25 vol %, and a total sulfur content below 0.30 mass %.

3. The method according to claim 1, further comprising utilizing a relationship between smoke point and concentration of cracked blendstock and/or a relationship between smoke point and concentration of synthesized paraffinic kerosine to assist in selecting appropriate amounts of different components in the jet fuel product.

4. The method according to claim 3, wherein measurement of smoke point is carried out with an automated procedure.

5. The method according to claim 1, wherein measurement of smoke point is carried out with an automated procedure.

6. The method according to claim 1, wherein the cracked blendstock comprises heavy cat naphtha from fluid catalytic cracking.

7. The method according to claim 1, wherein the synthesized paraffinic kerosine comprises hydrotreated vegetable oil (HVO).