Jet fuel with increased aromatics from olefin feedstocks

Abstract

This application discloses a process for making jet fuel including: (1) oligomerizing an olefin stream to an oligomer stream; (2) hydrogenating said oligomer stream to provide a paraffin stream; (3) separating said paraffin stream to provide a jet fuel stream and a reformer feed stream; and (4) reforming said reformer feed stream to provide a reformed stream with an increased concentration of aromatics.

Description

FIELD

[0001] This disclosure is generally directed to a process and apparatus for producing jet fuel with increased aromatics content from olefin feedstocks comprising ethylene, propylene, and / or higher olefins.BACKGROUND

[0002] There is an ever-increasing demand for sustainable aviation fuel (SAF) with high aromatics content. Unlike automobile engines, jet engines cannot be replaced easily by electrical motor systems because a high energy density is required to fuel planes which cannot be supplied with batteries. Large incentives are currently available for renewable jet fuel in certain regions. Other regions have announced planned mandates for renewable jet fuel to be gradually implemented in the coming decades to meet carbon dioxide emission reduction targets.

[0003] The growing interest in converting alcohol feedstocks such as ethanol to SAF with aromatics is clear. For example, the ASTM specification for synthetic hydrocarbons generated from alcohol feedstocks has recently been appended with the newly developed ASTM D7566 Annex 8 for ATJ-SKA (Alcohol to Jet-Synthetic Kerosene with Aromatics). Annex 8 specifies a jet fuel with 8.4-21.2 wt % (or 8-20 vol %) aromatics, where aromatics may be derived from C2-C5 alcohols, unlike earlier Alcohol To Jet pathways (e.g. Annex 5) where aromatics in the blended fuel product are primarily obtained from fossil fuel blending components.

[0004] To produce sustainable jet fuel feedstock, olefins derived from renewable sources can be oligomerized. Ethylene can be dimerized and oligomerized into olefins such as C4, C6, C8 and higher olefins. Propylene can be dimerized and oligomerized into olefins such as C6, C9, C12, and higher olefins. Ethylene and propylene can be co-oligomerized into olefins such as C5, C7 and higher olefins. Olefin oligomerization is an exothermic process that can oligomerize smaller olefins into larger olefins. More specifically, it can convert olefins including oligomerized olefins into a distillate including jet fuel and diesel range products. The oligomerized distillate can be saturated for use as transportation fuels.Measures must be taken to manage the exotherm generated in the oligomerization reactions, particularly the ethylene oligomerization. Diesel, naphtha, and / or jet product has been recycled to dilute ethylene oligomerization reactions to absorb the exotherm and dilute the oligomerization reactions occurring in the reactor. While oligomerization of olefins can be used to produce a product with molecular weight range appropriate for jet fuel can be utilized, an efficient process is desired for generating a sustainable jet fuel with increased aromatic content.SUMMARY

[0005] The present disclosure describes a process for making jet fuel including: (1) oligomerizing an olefin stream to an oligomer stream; (2) hydrogenating said oligomer stream to provide a paraffin stream; (3) separating said paraffin stream to provide a jet fuel stream and a reformer feed stream; (4) reforming said reformer feed stream to provide a reformed stream comprising an increased concentration of aromatics.

[0006] The present disclosure also describes an apparatus for making jet fuel including an oligomerization reactor having a first outlet stream. A hydrogenation reactor is in communication with the first outlet stream and has a second outlet stream. A jet fractionation column is in communication with the second outlet stream to separate the second outlet stream into a third outlet stream and a fourth outlet stream. A reformer reactor in communication with the third outlet stream to produce a fifth outlet stream with an increased aromatics content.

[0007] The present disclosure also describes an apparatus for making jet fuel including an oligomerization reactor having a first stage for forming a first oligomer stream and a second stage in communication with the first oligomer stream to form a second oligomer stream. A hydrogenation reactor is in communication with the second oligomer stream and has a hydrogenated hydrocarbon outlet stream. A jet fractionation column is in communication with the hydrogenated hydrocarbon outlet stream to separate the hydrocarbon outlet stream into a jet fuel outlet stream and a reformer outlet stream. A reformer reactor is in communication with the reformer outlet stream to produce a jet fuel stream with an increased aromatics content.

[0008] Other features and advantages of the invention will be apparent from the following specification taken in conjunction with the following Figures.BRIEF DESCRIPTION OF THE DRAWINGS

[0009] To understand the present invention, it will now be described by way of example, with reference to the accompanying drawings in which:

[0010] FIG. 1 is a schematic of an apparatus for preparing SAF with increased aromatics content.

[0011] FIG. 2 is a schematic of an apparatus for preparing SAF with increased aromatics including a naphtha splitter.

[0012] FIG. 3 is a schematic of an apparatus for preparing SAF with increased aromatics including an ethyl benzene alkylation reactor.

[0013] FIG. 4 is a schematic of an apparatus for preparing SAF with increased aromatics including a stripper for separating low fraction hydrocarbons from high fraction hydrocarbons.DEFINITIONS

[0014] The term “communication” means that fluid flow is operatively permitted between enumerated components, which may be characterized as “fluid communication”.

[0015] The term “downstream communication” means that at least a portion of fluid flowing to the subject in downstream communication may operatively flow from the object with which it fluidly communicates.

[0016] The term “upstream communication” means that at least a portion of the fluid flowing from the subject in upstream communication may operatively flow to the object with which it fluidly communicates.

[0017] The term “direct communication” means that fluid flow from the upstream component enters the downstream component without passing through any other intervening vessel.

[0018] The term “indirect communication” means that fluid flow from the upstream component enters the downstream component after passing through an intervening vessel.

[0019] As used herein, the term “separator” means a vessel which has an inlet and at least an overhead vapor outlet and a bottoms liquid outlet and may also have an aqueous stream outlet from a boot. A flash drum is a type of separator which may be in downstream communication with a separator that may be operated at higher pressure. As used herein, the term “boiling point temperature” means atmospheric equivalent boiling point (AEBP) as calculated from the observed boiling temperature and the distillation pressure, as calculated using the equations furnished in ASTM D1160 appendix A7 entitled “Practice for Converting Observed Vapor Temperatures to Atmospheric Equivalent Temperatures”.

[0020] The term “column” means a distillation column or columns for separating one or more components of different volatilities. Unless otherwise indicated, each column includes a condenser on an overhead of the column to condense and reflux a portion of an overhead stream back to the top of the column and a reboiler at a bottom of the column to vaporize and send a portion of a bottoms stream back to the bottom of the column. Feeds to the columns may be preheated. The top pressure is the pressure of the overhead vapor at the vapor outlet of the column. The bottom temperature is the liquid bottom outlet temperature. Overhead lines and bottoms lines refer to the net lines from the column downstream of any reflux or reboil to the column. Stripping columns may omit a reboiler at a bottom of the column and instead provide heating requirements and separation impetus from a fluidized inert media such as steam. Stripping columns typically feed a top tray and take main product from the bottom.

[0021] As used herein, the term “diesel” means hydrocarbons boiling in the range of an IBP between about 125° C. (257° F.) and about 175° C. (347° F.) or a T5 between about 150° C. (302° F.) and about 200° C. (392° F.) and the “diesel cut point” comprising a T95 between about 343° C. (650° F.) and about 399° C. (750° F.) using the TBP distillation method or a T90 between 280° C. (536° F.) and about 340° C. (644° F.) using ASTM D-86. The term “green diesel” means diesel comprising hydrocarbons not sourced from fossil fuels.

[0022] As used herein, the term “T5”, “T10”, “T90” or “T95” means the temperature at which 5 percent by mass or volume, 10 percent by mass or volume, 90 percent by mass or volume or 95 percent by mass or volume, as the case may be, respectively, of the sample boils using ASTM D-86 or TBP.

[0023] As used herein, the term “end point” (EP) means the temperature at which the sample has all boiled off using ASTM D-7169, ASTM D-86 or TBP, as the case may be.

[0024] As used herein, the term “jet fuel” means hydrocarbons boiling in the range of a T10 between about 190° C. (374° F.) and about 215° C. (419° F.) and an end point of between about 290° C. (554° F.) and about 310° C. (590° F.).

[0025] As used herein, the term “predominant” or “predominate” means greater than 50%, suitably greater than 75% and preferably greater than 90%.DETAILED DESCRIPTION

[0026] While this disclosure is susceptible of embodiments in many different forms, there is shown in the drawings and will herein be described in detail preferred embodiments of the invention with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the broad aspect of the invention to the embodiments illustrated.

[0027] FIG. 1 shows apparatus 10 for making jet fuel with increased aromatics content. The apparatus has an oligomerization reactor section 12, a hydrogenation reactor 14, a jet fractionation column 16, and a regeneration reformer or Platforming reactor 18. The oligomerization reactor section 12 has an inlet 20 and an outlet stream 22. The inlet 20 is charged with a pressurized stream of olefins 23 and produces the outlet stream 22 of C4-C25 olefins. The oligomerization reactor section may contain a first-stage oligomerization reactor followed by a second-stage oligomerization reactor in series.

[0028] The oligomerization reactors 12 converts ethylene, propylene, and / or C4-C8 olefins to higher jet range olefins. The oligomerization reaction generates a large exotherm. For example, dimerization of ethylene can generate 612 kcal / kg (1100 BTU / lb) of heat. To manage this exotherm, the olefin stream 23 is mixed with a second bottoms stream 50 to form a combined stream. The combined stream may be initially contacted with a first-stage oligomerization catalyst to oligomerize the olefins in the combined feed to oligomers and then contacted with a second oligomerization catalyst to oligomerize unconverted ethylene from the first-stage oligomerization. Alternatively, the combined stream may be initially contacted with a second stage oligomerization catalyst to oligomerize ethylene, and then be contacted with the first-stage oligomerization catalyst to oligomerize the oligomerized ethylene.

[0029] The combined stream may be at a temperature of about 35° C. (95° F.) to about 230° C. (446° F.), preferably about 80° C. (176° F.) to about 190° C. (374° F.), and a pressure of about 3.5 MPa(g) (500 psig), preferably about 5.6 MPa(g) (800 psig) to about 8.4 MPa(g) (1200 psig). The combined stream may comprise no more than 50 wt % olefins, suitably no more than 33 wt % olefins and preferably no more than 25 wt % olefins. In an embodiment, the combined stream comprises about 20 to about 40 wt % C2 to C8 olefins. The combined stream may comprise no more than 30 wt % ethylene, suitably no more than 25 wt % ethylene and preferably no more than 20 wt % ethylene. In an embodiment, the combined stream comprises about 10 to about 20 wt % ethylene. The combined stream may comprise no more than 50 wt % propylene, suitably no more than 33 wt % propylene and preferably no more than 20 wt % propylene. In an embodiment, the combined stream comprises about 10 to about 30 wt % propylene.

[0030] The first-stage oligomerization catalyst may include a zeolitic catalyst. The first-stage oligomerization catalyst may be considered a solid acid catalyst. The zeolite may comprise between about 5 and about 95 wt % of the catalyst, for example between about 5 and about 85 wt %. Suitable zeolites include zeolites having a structure from one of the following classes: MFI, MEL, ITH, IMF, TUN, FER, BEA, FAU, BPH, MEI, MSE, MWW, UZM-8, MOR, OFF, MTW, TON, MTT, AFO, ATO, and AEL. Three-letter codes indicating a zeotype are as defined by the Structure Commission of the International Zeolite Association and are maintained at http: / / www.iza-structure.org / databases. UZM-8 is as described in U.S. Pat. No. 6,756,030. In a preferred aspect, the first-stage oligomerization catalyst may comprise a zeolite with a framework having a ten-ring pore structure. Examples of suitable zeolites having a ten-ring pore structure include TON, MTT, MFI, MEL, AFO, AEL, EUO and FER. In a further preferred aspect, the first-stage oligomerization catalyst comprising a zeolite having a ten-ring pore structure may comprise a uni-dimensional pore structure. A uni-dimensional pore structure indicates zeolites containing non-intersecting pores that are substantially parallel to one of the axes of the crystal. The pores preferably extend through the zeolite crystal. Suitable examples of zeolites having a ten-ring uni-dimensional pore structure may include MTT. In a further aspect, the first-stage oligomerization catalyst comprises an MTT zeolite. A homogeneous first-stage catalyst is also contemplated.

[0031] It is contemplated using a spare parallel first-stage oligomerization reactor when the first-stage oligomerization reactor has deactivated during which the first-stage oligomerization reactor is regenerated in situ by combustion of coke from the catalyst. In another embodiment, each first-stage oligomerization reactor may comprise a lead reactor, a lag reactor and a spare reactor to facilitate regeneration.

[0032] The second-stage oligomerization catalyst is preferably an amorphous silica-alumina base with a metal from either Group VIIIB and / or Group VIB in the periodic table using Chemical Abstracts Service notations. In an aspect, the catalyst has a Group VIIIB metal promoted with a Group VIB metal. Typically, the silica and alumina will only be in the base, so the silica-to-alumina ratio will be the same for the catalyst as for the base. The metals can either be impregnated onto or ion exchanged with the silica-alumina base. Co-mulling is also contemplated. Catalyst bases other than amorphous silica-alumina can be contemplated as well. Catalysts for the present invention may have a Low Temperature Acidity Ratio of at least about 0.15, suitably of about 0.2, and preferably greater than about 0.25, as determined by Ammonia Temperature Programmed Desorption (Ammonia TPD) as described hereinafter. Additionally, a suitable catalyst will have a surface area of between about 50 and about 400 m2 / g as determined by nitrogen BET.

[0033] The first-stage oligomerization reaction takes place predominantly in the liquid phase or in a mixed liquid and gas phase at a WHSV 0.5 to 10 hr−1 on an olefin basis. We have found that across the first-stage oligomerization catalyst beds, typically about 30 to about 50 wt % ethylene in the olefin stream converts to higher olefins. The ethylene will initially dimerize over the catalyst to butenes. A predominance of the propylene and butenes in the olefins stream charged to a first-stage oligomerization catalyst bed is oligomerized. In an embodiment, at least 99 mol % of propylene and butenes in the olefins stream are oligomerized.

[0034] The second-stage oligomerization reactor may be in downstream communication with the first-stage oligomerization reactor. The second-stage oligomerization reactor preferably operates in a down flow operation. However, upflow operation may be suitable. The second-stage oligomerization charge stream is contacted with the second-stage oligomerization catalyst causing the unconverted ethylene and propylene from the first-stage oligomerization reactor to dimerize and trimerize while higher olefins also dimerize, trimerize and tetramerize to provide distillate range olefins. With regard to the second-stage oligomerization reactor, process conditions are selected to produce a higher percentage of jet range olefins which, when hydrogenated in the hydrogenation reactor 14, result in a desirable jet-range hydrocarbon product. A predominance of the unconverted ethylene from the first-stage oligomerization reactor is dimerized, trimerized and tetramerized. In an embodiment, at least 99 wt % of ethylene in the second-stage oligomerization charge stream is converted to mostly butenes. The outlet stream 22 contains C4-C25 olefins.

[0035] The preferred second-stage oligomerization catalyst comprises an amorphous silica-alumina support. One of the components of the catalyst support utilized in the present invention is alumina. The alumina may be any of the various hydrous aluminum oxides or alumina gels such as alpha-alumina monohydrate of the boehmite or pseudo-boehmite structure, alpha-alumina trihydrate of the gibbsite structure, beta-alumina trihydrate of the bayerite structure, and the like. A particularly preferred alumina is available from Sasol North America Alumina Product Group under the trademark CATAPAL. This material is an extremely high purity alpha-alumina monohydrate (pseudo-boehmite) which after calcination at a high temperature has been shown to yield a high purity gamma-alumina. Another component of the catalyst support is an amorphous silica-alumina. A suitable silica-alumina with a silica-to-alumina ratio of 2.6 is available from CCIC, a subsidiary of JGC, Japan.

[0036] The second-stage oligomerization catalyst can be regenerated upon deactivation. Suitable regeneration conditions include subjecting the catalyst, for example, in situ, to hot air at about 400 to about 500° C. for 3 hours. To facilitate regeneration without downtime, a swing bed arrangement may be employed with an alternative second-stage oligomerization reactor. The regeneration gas may comprise air with an increased or decreased concentration of oxygen.

[0037] Downstream of the oligomerization reactors 12, an olefin splitter column 24 has an inlet 26 in communication with the outlet stream 22 and produces a bottoms outlet stream 28 and an overhead outlet stream 30. The bottoms stream 28 contains C8+ olefins and is fed to the hydrogenation reactor 14 at a temperature from about 160° C. (320° F.) to about 190° C. (374° F.) and a pressure of about 3.9 MPa(g) (550 psig) to about 7 MPa(g) (1000 psig). The overhead stream 30 contains C4-C8 olefins. The overhead stream 30 is recycled to the oligomerization reactors 12. The olefins splitter column 24 is operated at a bottom temperature of about 232° C. (450° F.) to about 316° C. (600° F.) and an overhead pressure of about 207 kPa(g) (30 psig) to about 689 kPa(g) (100 psig). The overhead stream 30 is mixed with the incoming olefin feed stream 23 to form a combined input stream.

[0038] The hydrogenation reactor 14 having an inlet 32 is in downstream communication with the bottoms stream 28. The hydrogenation reactor 14 is charged with hydrogen gas H2 (not shown), that first mixes with input stream 28 of C8+ olefins to form a combined input stream. The combined stream is charged to the hydrogenation reactor 14 to saturate the olefinic bonds to provide an output stream 34 of C8+ paraffins. The bottoms stream 28 is charged to the hydrogenation reactor 14 at 125° C. (257° F.) to about 204° C. (400° F.) and 3.5 MPa (g) (500 psig) to about 6.9 MPa(g) (1000 psig). An excess of hydrogen may be employed to ensure complete saturation. The H2:olefin ratio in the hydrogenation reactor 14 may be from about 1.5 to about 2.5.

[0039] The hydrogenation reactor 14 uses a conventional hydrogenation or hydrotreating catalyst, and can include metallic catalysts containing, e.g., palladium, rhodium, nickel, ruthenium, platinum, rhenium, cobalt, molybdenum, or combinations thereof, and the supported versions thereof. Catalyst supports can be any solid, inert substance including, but not limited to, oxides such as silica, alumina, titania, calcium carbonate, barium sulfate, and carbons. The catalyst support can be in the form of powder, granules, pellets, or the like.

[0040] The jet fractionation column 16 having an inlet 36 is in downstream communication with the outlet stream 34 of the hydrogenation reactor 14. A reformed stream in line 66 is added to the hydrogenated outlet stream 34 before feeding the jet fractionation column 16. The jet fractionation column 16 separates the reformed stream and the hydrogenated outlet stream to produce a bottoms stream 40, an overhead stream 42, a first side outlet stream 44, and a second side outlet stream 46. The bottoms stream 40 contains C18+ paraffins. The jet fractionation column 16 separates the hydrocarbon inputs into various hydrocarbons. The jet fractionation column 16 may be operated at a bottoms temperature of about 288° C. (550° F.) to about 382° C. (720° F.) and an overhead absolute pressure of about 0 kPa (0 psia) to about 342 kPa (35 psia).

[0041] The bottoms stream 40 is split into two streams—a first bottoms stream 48 and a second bottoms stream 50. The first bottoms stream 48 is charged to a downstream diesel fractionator 52. The second bottoms stream 50 is mixed with the olefins stream 23 prior to being charged to the oligomerization reactor 12 to act as a recycle oil or diluent to absorb the exotherm in the oligomerization reactor 12. The ratio of the amounts of the second bottoms stream 50 and the olefins stream 23 is by weight from about 10:90 to about 90:10, more preferably from about 20:80 to about 70:30, and most preferably from about 20:80 to about 40:60.

[0042] The overhead stream 42 contains C7− paraffins that are cooled and fed to a jet fractionation receiver 54. The receiver 54 separates a fuel gas stream 56 from a naphtha stream 58. The fuel gas stream 56 is fed to the fuel gas header or further processed. The naphtha stream 58 is divided into two portions with a first portion 61 charged to the downstream reformer reactor 18 and a reformer feed portion 59 collected as a product. The ratio of the amounts of stream 59 to the hydrogenation effluent stream 34 is by weight from about 0.1 to about 15, more preferably from about 1 to about 10, and most preferably from about 2 to about 8.

[0043] The first side outlet stream 44 contains C12-C18 paraffins and after mixing with stream 60 is collected in a tank (not shown) or is otherwise collected as a jet fuel product stream. The second side outlet stream 46 contains C8-C11 paraffins and C8-C11 aromatics and a portion thereof in line 60 is mixed with the first bottoms stream 44 as part of the jet fuel product and a second portion is charged through line 62 to the reformer reactor 18.

[0044] The reformer reactor 18 receives input through inlet 64 from the stream 61 comprising C6-C7 naphtha and the reformer feed stream 62 comprising C8-C11 paraffins and aromatics as described above. The naphtha reformer feed portion in line 61 and the reformer feed in line 62 are combined to provide a combined reformer feed in line 65. The reformer converts paraffinic materials to aromatics to produce a mixture containing C6-C11 paraffins with a higher concentration of C6-C11 aromatics. The reformed stream 66 is discharged from the reforming reactor 18 to mix with the hydrogenation reactor outlet stream 34.

[0045] In the reformer reactor 18, the reactants may contact the catalyst in individual reactors in either upflow, downflow, or radial flow fashion, with the radial flow mode being preferred. The catalyst is contained in a fixed-bed system or a moving-bed system with associated continuous catalyst regeneration. The preferred embodiment of the current invention is a fixed-bed system. Alternative approaches to reactivation of the catalyst are as follows:

[0046] Semi-regenerative: The entire unit is operated to maintain activity by gradually increasing temperature to maintain product octane number, finally shutting the unit down for catalyst regeneration and reactivation. Swing reactor or Cyclic: Individual reactors are individually isolated by manifolding arrangements. As the contained catalyst becomes deactivated, the catalyst in the isolated reactor is regenerated and reactivated while the other reactors remain on-stream. Continuous: Catalyst is continuously withdrawn from the reactors by means of a slowly moving bed, and the catalyst is regenerated and reactivated before being returned to the reactors. This system permits higher operating severity and maintains high catalyst activity by reactivating each catalyst particle over a period of a few days. Hybrid: Semi-regenerative and continuous reactors are contained in the same unit. Usually this is effected by adding a continuous reactor to an existing semi-regenerative process unit to provide for higher severity operation with improved selectivity. The preferred embodiment of the current invention is a “semi-regenerative” although the others are suitable.

[0047] Operating conditions used for the reforming process of the present invention include a pressure selected within the range of about 100 to about 7000 kPa (abs), with the preferred pressure being about 350 kPa to about 4250 kPa (abs). Particularly good results are obtained at low pressure, namely a pressure of about 350 to about 2500 kPa. Reforming conditions include a temperature in the range from about 315° to about 600° C. and preferably from about 425° to about 565° C. The initial selection of the temperature within this range is made primarily as a function of the desired aromatics content of the product reformate considering the characteristics of the charge stock and of the catalyst. Ordinarily, the temperature then is thereafter slowly increased during the run to compensate for the inevitable deactivation that occurs to provide a constant aromatics concentration in the product. Multiple reforming reactors may be employed with interstage heating between reactors or heating applied to each reactor.

[0048] Suitable catalysts include a dual-function catalyst having a multi-metallic, combination of two or more metal components in specified concentrations on the finished catalyst, and its use in hydrocarbon conversion with increased aromatics production. Catalysts having both a hydrogenation-dehydrogenation function and a cracking function should maximize the former and minimize the latter. The cracking function generally relates to an acid-action material of the porous, adsorptive, refractory-oxide type which is typically utilized as the support or carrier for a heavy-metal component, such as the Group VIII (IUPAC 8-10) metals, which primarily contribute the hydrogenation-dehydrogenation function. Other metals in combined or elemental form can influence one or both of the cracking and hydrogenation-dehydrogenation functions.

[0049] Catalytic reforming involves a number of competing processes or reaction sequences. These include dehydrogenation of cyclohexanes to aromatics, dehydroisomerization of alkylcyclopentanes to aromatics, dehydrocyclization of an acyclic hydrocarbon to aromatics, dealkylation of alkylbenzenes and isomerization of paraffins. Hydrocracking reactions which produce light paraffin gases have a deleterious effect on the yield of products boiling in the jet fuel range. Process improvements in catalytic reforming thus are targeted toward enhancing those reactions effecting a higher yield of the liquid products containing more 5 or more carbon atoms and minimizing those reactions affecting cracked products containing 4 or fewer carbon atoms.

[0050] Generally, it is desirable to have flexibility with catalyst functionality for reforming. In one exemplary reforming process, increasing the yield of one or more C5+ hydrocarbons, hydrogen, and aromatic yields is desired. Optionally, the acidity of the catalyst can be altered by adding a metal and / or other elements to the catalyst. Generally, modification of the acid function results in reduced cracking of the alkanes to C3 and C4 light ends allowing increased selectivity to the formation of aromatics. Modification of the metal function may also occur resulting in the reduction of alkane cracking to methane and ethane. There can also be a reduction in the dealkylation reactions of aromatics leaving heavier and more valuable C8+ aromatics.

[0051] Beside the yields, the activity of a catalyst may enable obtaining a commercially useful conversion level without employing additional quantities of catalyst or using excessively high temperatures, which can lead to undesired higher costs. Higher catalyst activity can also be utilized to process greater quantities of feed or to increase conversion, and therefore increase the production of valuable products.

[0052] Catalytic materials used for reforming paraffinic feeds more selectively towards aromatics can be achieved by tuning the material acidity. In one embodiment, the catalytic material comprises a refractory aluminum oxide support, a metal from the platinum group, such as Re, and a halogen element.

[0053] The reformed stream in line 66 and the hydrogenated stream in line 34 are together fed in line 35 to the jet fractionation column 16 as previously mentioned.

[0054] The diesel fractionator 52 separates the first bottoms stream in line 48 from the jet fractionation column 16 to produce two outlet streams—a first overhead stream in an overhead line 72 and a second bottoms stream in a bottoms line 74. The first overhead stream 72 contains diesel fuel and is collected as a diesel product. The second outlet stream 74 contains heavy oil which is collected as product and perhaps used as lube base stock or further processed in an FCC unit or a hydrocracking unit.

[0055] FIG. 2 shows a second embodiment 100 of an apparatus and process for producing jet fuel with increased aromatics content that differs from that of FIG. 1 in the ordering of some of the reactors. The second embodiment 100 has the reformer reactor 18 positioned to receive a stream of C8-C11 paraffins from the second side outlet stream 46 and produces a reformed stream 166 which is fed to a downstream splitter column 180. The splitter column 180 separates a bottoms outlet stream 182 containing C8-C11 paraffins and C8-C11 aromatics and is mixed with the second side outlet stream 44 comprising C12-C18 paraffins. The splitter 180 has an overhead outlet stream 184 that is cooled and fed to a receiver 186 that separates a fuel gas stream 188 from a naphtha stream 190. In a further embodiment, the naphtha in line 58 from the jet fractionator column overhead could be added to the reformer feed stream in line 46 to be reformed in the reforming reactor 18. The splitter column 180 operates at a bottom temperature of about 232° C. (450° F.) to about 316° C. (600° F.) and an overhead pressure of about 207 kPa (30 psig) to about 689 kPa (100 psig).

[0056] FIG. 3 shows a third embodiment 200 of an apparatus and process for producing jet fuel with an increased aromatics content that is like that of FIG. 1 with a few exceptions. The third embodiment utilizes an ethylbenzene alkylation reactor 219 to increase the carbon number of the reformed stream by recourse to an ethylene alkylation agent. The ethylbenzene alkylation reactor 219 is charged by an alkylating agent input line 220 of ethylene and the reformed stream in line 266 comprising C6-C11 paraffins and aromatics and produces an outlet stream 235 comprising C8-C13 aromatics and C6-C11 paraffins. The outlet stream 235 mixes with the hydrogenation reactor output stream 34 to form a combined stream 35. The combined stream 35 is fed to jet fractionation column 16 through inlet 36. Alkylation involves the transfer of an alkyl group from an alkylating agent to an aromatic substrate widely referred to as an electrophilic aromatic substitution reaction. In the alkylation reactor 219, C6-C11 alkylaromatics are produced by catalytically reacting the reformed stream 266 from the reformer reactor 18 with the alkylating agent in the presence of an alkylation catalyst at an alkylation temperature and alkylation pressure to produce an alkylated stream 235 comprising C8-C13 aromatics and C6-C11 paraffins. The alkylation reaction is conducted at a temperature where the thermodynamics are favorable. In an embodiment, the alkylation unit 219 may be operated at a temperature of about 149° C. to about 482° C. and a pressure of about 1000 kPa (10 bar) to 14000 kPa (140 bar). Weight hourly space velocity (WHSV) for the alkylation reactor may range from about 4 hr−1 to about 100 hr−1. Aromatics to alkylating agent ratio for the reactor may range from 1 to 15 mol ratio.

[0057] In an aspect, the alkylation catalyst may comprise one or more from the group comprising sulfuric acid, hydrofluoric acid, aluminum chloride, boron trifluoride, solid phosphoric acid, chlorided alumina, acidic alumina, aluminum phosphate, silica-alumina phosphate, amorphous silica-alumina, aluminosilicate, aluminosilicate zeolite, zirconia, sulfated zirconia, tungstated zirconia, tungsten carbide, molybdenum carbide, titania, sulfated carbon, phosphated carbon, phosphated silica, phosphated alumina, acidic resin, heteropolyacid, inorganic acid, and a combination of any two or more of the foregoing.

[0058] In one embodiment, the alkylation catalyst comprises an aluminosilicate zeolite. In one version, the alkylation catalyst further comprises a modifier selected from the group consisting of Ga, In, Zn, Fe, Mo, Ag, Au, Ni, P, Sc, Y, Ta, a lanthanide, and a combination of any two or more of the foregoing. In another version, the alkylation catalyst further comprises a metal selected from the group consisting of Cu, Ag, Au, Pt, Ni, Fe, Co, Ru, Zn, Cd, Ga, In, Rh, Pd, Ir, Re, Mn, Cr, Mo, W, Sn, Os, an alloy of any two or more of the foregoing, and a combination of any two or more of the foregoing.

[0059] In an embodiment, the alkylation catalyst may be selected from zeolite catalyst or ionic liquid catalyst. In an exemplary embodiment, the alkylation catalyst comprises a SAPO based catalyst.

[0060] FIG. 4 shows a fourth embodiment 300 of an apparatus for producing jet fuel with an increased aromatics content that is like that of FIG. 1 with a few exceptions.

[0061] Downstream of the hydrogenation reactor 18 is a stripper column 315 having an inlet stream 317 that is the combination of the hydrogenation reactor output stream 34 and the first outlet stream 66 from the reformer reactor 18. The stripper column 315 separates low fraction hydrocarbons from higher fraction hydrocarbons. The stripper column 315 produces an output stream 333 of C7 and C8 hydrocarbons which is fed to the jet fractionation column 316. The bottoms outlet stream 319 contains C9-C11 aromatics and C9+ paraffins and is separated into two portions 353 and 355. The stripper column operates at a bottom temperature of about 232° C. (450° F.) to about 371° C. (700° F.) and an overhead pressure of about 207 kPa (30 psig) to about 689 kPa (100 psig). The ratio of the amounts of the first portion 353 to the olefin feed 23 is by weight from about 10:90 to about 90:10, more preferably from about 20:80 to about 70:30, and most preferably from about 20:80 to about 60:40.

[0062] The first portion 353 is a diluent that is recycled back to the oligomerization reactor 12 and mixes with the olefins stream 23 to form a combined input stream. The diluent serves to absorb the exotherm. The second portion 355 is fed to an inlet 336 to the jet fractionation column 316.

[0063] The condenser (not shown) provides an overhead stream 329 containing fuel gas which is sent to a fuel gas header or further processed and a liquid outlet stream 321 containing naphtha and is divided into a first naphtha stream 325 and a second naphtha stream 327. The first naphtha stream 325 is collected as a product. The second naphtha stream 327 is charged to an inlet 364 to the reformer reactor 18.

[0064] The jet fractionation column 316 produces a bottoms stream 340, an overhead stream 342, and a first side outlet stream 344. The first side outlet stream 344 contains C12-C18 paraffins and is collected as a jet fuel product. The bottoms stream 340 contains C18+ paraffins which can be collected for use as a diesel product or charged to a diesel fuel fractionator as described above. The overhead stream 342 comprises C8-C11 paraffins and C8-C11 aromatics that is divided into a first overhead stream 343 and a second overhead stream 345.

[0065] The first overhead stream 343 is mixed with the side outlet stream 344 to provide a synthetic aviation fuel line 350. The second overhead stream 345 is mixed with the second naphtha stream 327 and charged to the reforming reactor 18.

[0066] Many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood within the scope of the appended claims the invention may be protected otherwise than as specifically described. The description in the present application should not be read as implying that any particular element, step, or function is an essential or critical element that must be included in the claim scope. The scope of patented subject matter is defined only by the allowed claims. Moreover, none of the claims invokes 35 U.S.C. § 112(f) with respect to any of the appended claims or claim elements unless the exact words “means for” or “step for” are explicitly used in the particular claim, followed by a participle phrase identifying a function. Use of terms such as (but not limited to) “mechanism,”“module,”“device,”“unit,”“component,”“element,”“member,”“apparatus,”“machine,”“vessel,” or “system,” within a claim is understood and intended to refer to structures known to those skilled in the relevant art, as further modified or enhanced by the features of the claims themselves, and is not intended to invoke 35 U.S.C. § 112(f).

[0067] While this disclosure has described certain embodiments and generally associated methods, alterations and permutations of these embodiments and methods will be apparent to those skilled in the art. Accordingly, the above description of example embodiments does not define or constrain this disclosure. Other changes, substitutions, and alterations are also possible without departing from the spirit and scope of this disclosure, as defined by the following claims.EXAMPLE

[0068] The following Example is presented to only illustrate one possible application of the invention and should not be used to limit the scope of the invention as described in the claims. Many other possible variations may occur within the span of the invention.Example 1

[0069] An olefin stream was fed to an oligomerization reactor to make an oligomer stream. The oligomer stream was fed to a hydrogenation reactor to make a paraffinic stream. The paraffinic stream was separated into a jet fuel stream and a reformer feed stream. The composition of the reformer feed stream can be found in Table 1.TABLE 1Reformer Feed Mass Composition (wt %)CarbonNo.ParaffinOlefinNaphtheneAromaticTotal10000020000030000040000050000060000070000081.9507.8209.77938.3300038.3310 14.3100014.3111+37.5900037.59Total92.1807.820100.00

[0070] The reformer feed was fed to a reformer reactor to produce the reformed stream with increased aromatics, as shown in Table 2.TABLE 2Reformed Stream Mass Composition (wt %)CarbonNo.ParaffinOlefinNaphtheneAromaticTotal11.890001.8923.970003.9735.370.01005.3746.700.03006.7355.100.05005.1565.190.060.030.385.6675.940.070.041.978.0183.690.050.0711.0114.8296.530.080.1217.7924.5110 1.8000.034.676.4911+1.1400.0414.1015.28Total47.310.330.3349.9297.89

[0071] The reformed stream was fed to a splitter to remove the components that are too light for Jet blending. The reformed jet cut was then combined with the jet fuel stream from the jet fractionator to form the final jet fuel blend.SPECIFIC EMBODIMENTS

[0072] While the following is described in conjunction with specific embodiments, it will be understood that this description is intended to illustrate and not limit the scope of the preceding description and the appended claims.

[0073] A first embodiment of the disclosure is a process for making jet fuel or jet fuel blend stock comprising oligomerizing an olefin stream to an oligomer stream; hydrogenating the oligomer stream to provide a paraffin stream; separating the paraffin stream to provide a jet fuel stream and a reformer feed stream; reforming the reformer feed stream to provide a reformed stream comprising an increased concentration of aromatics. An embodiment of the disclosure is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the olefin feed is ethylene. An embodiment of the disclosure is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the olefin feed consists of a mixture of olefinic species within the carbon number range of C2-C8. An embodiment of the disclosure is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph further comprising mixing the reformed stream with the paraffin stream. An embodiment of the disclosure is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph further comprising alkylating ethylene with aromatics in the reformer stream to provide an alkylated aromatics stream. An embodiment of the disclosure is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph further comprising mixing the alkylated aromatics stream with the paraffin stream. An embodiment of the disclosure is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph further comprising oligomerizing the olefins stream in a first stage and further oligomerizing a first stage oligomer stream in a second stage to provide the oligomer stream. An embodiment of the disclosure is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the first stage uses a zeolite-type catalyst, and the second stage uses an amorphous silica-alumina base with a metal from either Group VIIIB and / or Group VIB in the periodic table using Chemical Abstracts Service notations. An embodiment of the disclosure is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the first stage uses an amorphous silica-alumina base with a metal from either Group VIIIB and / or Group VIB in the periodic table using Chemical Abstracts Service notations catalyst and the second stage uses a zeolite-type. An embodiment of the disclosure is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the reformer feed stream comprises C6 to C11 paraffins. An embodiment of the disclosure is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph further providing a jet fractionation column having a first side outlet producing the jet fuel stream and a second side outlet producing the reformer stream. An embodiment of the disclosure is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph further comprising a splitter column to separate the reformed stream into a naphtha stream and a C8 to C11 hydrocarbon stream and further comprising mixing the C8 to C11 stream with the jet fuel stream. An embodiment of the disclosure is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the step of reforming utilizes a catalyst comprising a refractory aluminum oxide support, a platinum component, a germanium, a tin, or a rhenium component or a combination thereof, and a halogen component. An embodiment of the disclosure is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the step of reforming produces a hydrogen stream that is in communication with the hydrogenating step.

[0074] A second embodiment of the disclosure is an apparatus for making jet fuel comprising an oligomerization reactor having a first outlet stream; a hydrogenation reactor in communication with the first outlet stream and having a second outlet stream; a jet fractionation column in communication with the second outlet stream to separate the second outlet stream into a third outlet stream and a fourth outlet stream; and, a reformer reactor in communication with the third outlet stream to produce a fifth outlet stream with an increased aromatics content. An embodiment of the disclosure is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph further comprising an aromatics alkylation reactor in communication with the fourth outlet stream to form a sixth outlet stream. An embodiment of the disclosure is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph wherein the jet fractionation column has a first side outlet producing the third outlet stream and a second side outlet producing the fourth outlet stream.

[0075] A third embodiment of the disclosure is an apparatus for making jet fuel comprising an oligomerization reactor having a first stage for forming a first oligomer stream and a second stage in communication with the first oligomer stream to form a second oligomer stream; a hydrogenation reactor in communication with the second oligomer stream and having a hydrogenated hydrocarbon outlet stream; a fractionation column in communication with the hydrogenated hydrocarbon outlet stream to separate the hydrocarbon outlet stream into a jet fuel outlet stream and a reformer outlet stream; and, a reformer reactor in communication with the reformer outlet stream to produce a jet fuel stream with an increased aromatics content. An embodiment of the disclosure is one, any or all of prior embodiments in this paragraph up through the third embodiment in this paragraph further comprising an aromatics alkylation reactor in communication with the reformer outlet stream. An embodiment of the disclosure is one, any or all of prior embodiments in this paragraph up through the third embodiment in this paragraph wherein the fractionator column is a jet fractionator having a first side outlet and a second side outlet, the first side outlet produces the jet fuel outlet stream, and the second side outlet produces the reformer outlet stream.

[0076] Without further elaboration, it is believed that using the preceding description that one skilled in the art can utilize the present disclosure to its fullest extent and easily ascertain the essential characteristics of this disclosure, without departing from the spirit and scope thereof, to make various changes and modifications of the disclosure and to adapt it to various usages and conditions. The preceding preferred specific embodiments are, therefore, to be construed as merely illustrative, and not limiting the remainder of the disclosure in any way whatsoever, and that it is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims.

[0077] In the foregoing, all temperatures are set forth in degrees Celsius and, all parts and percentages are by weight, unless otherwise indicated.

Examples

example 1

[0069]An olefin stream was fed to an oligomerization reactor to make an oligomer stream. The oligomer stream was fed to a hydrogenation reactor to make a paraffinic stream. The paraffinic stream was separated into a jet fuel stream and a reformer feed stream. The composition of the reformer feed stream can be found in Table 1.

TABLE 1Reformer Feed Mass Composition (wt %)CarbonNo.ParaffinOlefinNaphtheneAromaticTotal10000020000030000040000050000060000070000081.9507.8209.77938.3300038.3310 14.3100014.3111+37.5900037.59Total92.1807.820100.00

[0070]The reformer feed was fed to a reformer reactor to produce the reformed stream with increased aromatics, as shown in Table 2.

TABLE 2Reformed Stream Mass Composition (wt %)CarbonNo.ParaffinOlefinNaphtheneAromaticTotal11.890001.8923.970003.9735.370.01005.3746.700.03006.7355.100.05005.1565.190.060.030.385.6675.940.070.041.978.0183.690.050.0711.0114.8296.530.080.1217.7924.5110 1.8000.034.676.4911+1.1400.0414.1015.28Total47.310.330.3349.9297.89

[0071]...

specific embodiments

[0072]While the following is described in conjunction with specific embodiments, it will be understood that this description is intended to illustrate and not limit the scope of the preceding description and the appended claims.

[0073]A first embodiment of the disclosure is a process for making jet fuel or jet fuel blend stock comprising oligomerizing an olefin stream to an oligomer stream; hydrogenating the oligomer stream to provide a paraffin stream; separating the paraffin stream to provide a jet fuel stream and a reformer feed stream; reforming the reformer feed stream to provide a reformed stream comprising an increased concentration of aromatics. An embodiment of the disclosure is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the olefin feed is ethylene. An embodiment of the disclosure is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the olefin ...

FIELD

[0001] This disclosure is generally directed to a process and apparatus for producing jet fuel with increased aromatics content from olefin feedstocks comprising ethylene, propylene, and / or higher olefins.BACKGROUND

[0002] There is an ever-increasing demand for sustainable aviation fuel (SAF) with high aromatics content. Unlike automobile engines, jet engines cannot be replaced easily by electrical motor systems because a high energy density is required to fuel planes which cannot be supplied with batteries. Large incentives are currently available for renewable jet fuel in certain regions. Other regions have announced planned mandates for renewable jet fuel to be gradually implemented in the coming decades to meet carbon dioxide emission reduction targets.

[0003] The growing interest in converting alcohol feedstocks such as ethanol to SAF with aromatics is clear. For example, the ASTM specification for synthetic hydrocarbons generated from alcohol feedstocks has recently been appended with the newly developed ASTM D7566 Annex 8 for ATJ-SKA (Alcohol to Jet-Synthetic Kerosene with Aromatics). Annex 8 specifies a jet fuel with 8.4-21.2 wt % (or 8-20 vol %) aromatics, where aromatics may be derived from C2-C5 alcohols, unlike earlier Alcohol To Jet pathways (e.g. Annex 5) where aromatics in the blended fuel product are primarily obtained from fossil fuel blending components.

[0004] To produce sustainable jet fuel feedstock, olefins derived from renewable sources can be oligomerized. Ethylene can be dimerized and oligomerized into olefins such as C4, C6, C8 and higher olefins. Propylene can be dimerized and oligomerized into olefins such as C6, C9, C12, and higher olefins. Ethylene and propylene can be co-oligomerized into olefins such as C5, C7 and higher olefins. Olefin oligomerization is an exothermic process that can oligomerize smaller olefins into larger olefins. More specifically, it can convert olefins including oligomerized olefins into a distillate including jet fuel and diesel range products. The oligomerized distillate can be saturated for use as transportation fuels.Measures must be taken to manage the exotherm generated in the oligomerization reactions, particularly the ethylene oligomerization. Diesel, naphtha, and / or jet product has been recycled to dilute ethylene oligomerization reactions to absorb the exotherm and dilute the oligomerization reactions occurring in the reactor. While oligomerization of olefins can be used to produce a product with molecular weight range appropriate for jet fuel can be utilized, an efficient process is desired for generating a sustainable jet fuel with increased aromatic content.SUMMARY

[0005] The present disclosure describes a process for making jet fuel including: (1) oligomerizing an olefin stream to an oligomer stream; (2) hydrogenating said oligomer stream to provide a paraffin stream; (3) separating said paraffin stream to provide a jet fuel stream and a reformer feed stream; (4) reforming said reformer feed stream to provide a reformed stream comprising an increased concentration of aromatics.

[0006] The present disclosure also describes an apparatus for making jet fuel including an oligomerization reactor having a first outlet stream. A hydrogenation reactor is in communication with the first outlet stream and has a second outlet stream. A jet fractionation column is in communication with the second outlet stream to separate the second outlet stream into a third outlet stream and a fourth outlet stream. A reformer reactor in communication with the third outlet stream to produce a fifth outlet stream with an increased aromatics content.

[0007] The present disclosure also describes an apparatus for making jet fuel including an oligomerization reactor having a first stage for forming a first oligomer stream and a second stage in communication with the first oligomer stream to form a second oligomer stream. A hydrogenation reactor is in communication with the second oligomer stream and has a hydrogenated hydrocarbon outlet stream. A jet fractionation column is in communication with the hydrogenated hydrocarbon outlet stream to separate the hydrocarbon outlet stream into a jet fuel outlet stream and a reformer outlet stream. A reformer reactor is in communication with the reformer outlet stream to produce a jet fuel stream with an increased aromatics content.

[0008] Other features and advantages of the invention will be apparent from the following specification taken in conjunction with the following Figures.BRIEF DESCRIPTION OF THE DRAWINGS

[0009] To understand the present invention, it will now be described by way of example, with reference to the accompanying drawings in which:

[0010] FIG. 1 is a schematic of an apparatus for preparing SAF with increased aromatics content.

[0011] FIG. 2 is a schematic of an apparatus for preparing SAF with increased aromatics including a naphtha splitter.

[0012] FIG. 3 is a schematic of an apparatus for preparing SAF with increased aromatics including an ethyl benzene alkylation reactor.

[0013] FIG. 4 is a schematic of an apparatus for preparing SAF with increased aromatics including a stripper for separating low fraction hydrocarbons from high fraction hydrocarbons.DEFINITIONS

[0014] The term “communication” means that fluid flow is operatively permitted between enumerated components, which may be characterized as “fluid communication”.

[0015] The term “downstream communication” means that at least a portion of fluid flowing to the subject in downstream communication may operatively flow from the object with which it fluidly communicates.

[0016] The term “upstream communication” means that at least a portion of the fluid flowing from the subject in upstream communication may operatively flow to the object with which it fluidly communicates.

[0017] The term “direct communication” means that fluid flow from the upstream component enters the downstream component without passing through any other intervening vessel.

[0018] The term “indirect communication” means that fluid flow from the upstream component enters the downstream component after passing through an intervening vessel.

[0019] As used herein, the term “separator” means a vessel which has an inlet and at least an overhead vapor outlet and a bottoms liquid outlet and may also have an aqueous stream outlet from a boot. A flash drum is a type of separator which may be in downstream communication with a separator that may be operated at higher pressure. As used herein, the term “boiling point temperature” means atmospheric equivalent boiling point (AEBP) as calculated from the observed boiling temperature and the distillation pressure, as calculated using the equations furnished in ASTM D1160 appendix A7 entitled “Practice for Converting Observed Vapor Temperatures to Atmospheric Equivalent Temperatures”.

[0020] The term “column” means a distillation column or columns for separating one or more components of different volatilities. Unless otherwise indicated, each column includes a condenser on an overhead of the column to condense and reflux a portion of an overhead stream back to the top of the column and a reboiler at a bottom of the column to vaporize and send a portion of a bottoms stream back to the bottom of the column. Feeds to the columns may be preheated. The top pressure is the pressure of the overhead vapor at the vapor outlet of the column. The bottom temperature is the liquid bottom outlet temperature. Overhead lines and bottoms lines refer to the net lines from the column downstream of any reflux or reboil to the column. Stripping columns may omit a reboiler at a bottom of the column and instead provide heating requirements and separation impetus from a fluidized inert media such as steam. Stripping columns typically feed a top tray and take main product from the bottom.

[0021] As used herein, the term “diesel” means hydrocarbons boiling in the range of an IBP between about 125° C. (257° F.) and about 175° C. (347° F.) or a T5 between about 150° C. (302° F.) and about 200° C. (392° F.) and the “diesel cut point” comprising a T95 between about 343° C. (650° F.) and about 399° C. (750° F.) using the TBP distillation method or a T90 between 280° C. (536° F.) and about 340° C. (644° F.) using ASTM D-86. The term “green diesel” means diesel comprising hydrocarbons not sourced from fossil fuels.

[0022] As used herein, the term “T5”, “T10”, “T90” or “T95” means the temperature at which 5 percent by mass or volume, 10 percent by mass or volume, 90 percent by mass or volume or 95 percent by mass or volume, as the case may be, respectively, of the sample boils using ASTM D-86 or TBP.

[0023] As used herein, the term “end point” (EP) means the temperature at which the sample has all boiled off using ASTM D-7169, ASTM D-86 or TBP, as the case may be.

[0024] As used herein, the term “jet fuel” means hydrocarbons boiling in the range of a T10 between about 190° C. (374° F.) and about 215° C. (419° F.) and an end point of between about 290° C. (554° F.) and about 310° C. (590° F.).

[0025] As used herein, the term “predominant” or “predominate” means greater than 50%, suitably greater than 75% and preferably greater than 90%.DETAILED DESCRIPTION

[0026] While this disclosure is susceptible of embodiments in many different forms, there is shown in the drawings and will herein be described in detail preferred embodiments of the invention with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the broad aspect of the invention to the embodiments illustrated.

[0027] FIG. 1 shows apparatus 10 for making jet fuel with increased aromatics content. The apparatus has an oligomerization reactor section 12, a hydrogenation reactor 14, a jet fractionation column 16, and a regeneration reformer or Platforming reactor 18. The oligomerization reactor section 12 has an inlet 20 and an outlet stream 22. The inlet 20 is charged with a pressurized stream of olefins 23 and produces the outlet stream 22 of C4-C25 olefins. The oligomerization reactor section may contain a first-stage oligomerization reactor followed by a second-stage oligomerization reactor in series.

[0028] The oligomerization reactors 12 converts ethylene, propylene, and / or C4-C8 olefins to higher jet range olefins. The oligomerization reaction generates a large exotherm. For example, dimerization of ethylene can generate 612 kcal / kg (1100 BTU / lb) of heat. To manage this exotherm, the olefin stream 23 is mixed with a second bottoms stream 50 to form a combined stream. The combined stream may be initially contacted with a first-stage oligomerization catalyst to oligomerize the olefins in the combined feed to oligomers and then contacted with a second oligomerization catalyst to oligomerize unconverted ethylene from the first-stage oligomerization. Alternatively, the combined stream may be initially contacted with a second stage oligomerization catalyst to oligomerize ethylene, and then be contacted with the first-stage oligomerization catalyst to oligomerize the oligomerized ethylene.

[0029] The combined stream may be at a temperature of about 35° C. (95° F.) to about 230° C. (446° F.), preferably about 80° C. (176° F.) to about 190° C. (374° F.), and a pressure of about 3.5 MPa(g) (500 psig), preferably about 5.6 MPa(g) (800 psig) to about 8.4 MPa(g) (1200 psig). The combined stream may comprise no more than 50 wt % olefins, suitably no more than 33 wt % olefins and preferably no more than 25 wt % olefins. In an embodiment, the combined stream comprises about 20 to about 40 wt % C2 to C8 olefins. The combined stream may comprise no more than 30 wt % ethylene, suitably no more than 25 wt % ethylene and preferably no more than 20 wt % ethylene. In an embodiment, the combined stream comprises about 10 to about 20 wt % ethylene. The combined stream may comprise no more than 50 wt % propylene, suitably no more than 33 wt % propylene and preferably no more than 20 wt % propylene. In an embodiment, the combined stream comprises about 10 to about 30 wt % propylene.

[0030] The first-stage oligomerization catalyst may include a zeolitic catalyst. The first-stage oligomerization catalyst may be considered a solid acid catalyst. The zeolite may comprise between about 5 and about 95 wt % of the catalyst, for example between about 5 and about 85 wt %. Suitable zeolites include zeolites having a structure from one of the following classes: MFI, MEL, ITH, IMF, TUN, FER, BEA, FAU, BPH, MEI, MSE, MWW, UZM-8, MOR, OFF, MTW, TON, MTT, AFO, ATO, and AEL. Three-letter codes indicating a zeotype are as defined by the Structure Commission of the International Zeolite Association and are maintained at http: / / www.iza-structure.org / databases. UZM-8 is as described in U.S. Pat. No. 6,756,030. In a preferred aspect, the first-stage oligomerization catalyst may comprise a zeolite with a framework having a ten-ring pore structure. Examples of suitable zeolites having a ten-ring pore structure include TON, MTT, MFI, MEL, AFO, AEL, EUO and FER. In a further preferred aspect, the first-stage oligomerization catalyst comprising a zeolite having a ten-ring pore structure may comprise a uni-dimensional pore structure. A uni-dimensional pore structure indicates zeolites containing non-intersecting pores that are substantially parallel to one of the axes of the crystal. The pores preferably extend through the zeolite crystal. Suitable examples of zeolites having a ten-ring uni-dimensional pore structure may include MTT. In a further aspect, the first-stage oligomerization catalyst comprises an MTT zeolite. A homogeneous first-stage catalyst is also contemplated.

[0031] It is contemplated using a spare parallel first-stage oligomerization reactor when the first-stage oligomerization reactor has deactivated during which the first-stage oligomerization reactor is regenerated in situ by combustion of coke from the catalyst. In another embodiment, each first-stage oligomerization reactor may comprise a lead reactor, a lag reactor and a spare reactor to facilitate regeneration.

[0032] The second-stage oligomerization catalyst is preferably an amorphous silica-alumina base with a metal from either Group VIIIB and / or Group VIB in the periodic table using Chemical Abstracts Service notations. In an aspect, the catalyst has a Group VIIIB metal promoted with a Group VIB metal. Typically, the silica and alumina will only be in the base, so the silica-to-alumina ratio will be the same for the catalyst as for the base. The metals can either be impregnated onto or ion exchanged with the silica-alumina base. Co-mulling is also contemplated. Catalyst bases other than amorphous silica-alumina can be contemplated as well. Catalysts for the present invention may have a Low Temperature Acidity Ratio of at least about 0.15, suitably of about 0.2, and preferably greater than about 0.25, as determined by Ammonia Temperature Programmed Desorption (Ammonia TPD) as described hereinafter. Additionally, a suitable catalyst will have a surface area of between about 50 and about 400 m2 / g as determined by nitrogen BET.

[0033] The first-stage oligomerization reaction takes place predominantly in the liquid phase or in a mixed liquid and gas phase at a WHSV 0.5 to 10 hr−1 on an olefin basis. We have found that across the first-stage oligomerization catalyst beds, typically about 30 to about 50 wt % ethylene in the olefin stream converts to higher olefins. The ethylene will initially dimerize over the catalyst to butenes. A predominance of the propylene and butenes in the olefins stream charged to a first-stage oligomerization catalyst bed is oligomerized. In an embodiment, at least 99 mol % of propylene and butenes in the olefins stream are oligomerized.

[0034] The second-stage oligomerization reactor may be in downstream communication with the first-stage oligomerization reactor. The second-stage oligomerization reactor preferably operates in a down flow operation. However, upflow operation may be suitable. The second-stage oligomerization charge stream is contacted with the second-stage oligomerization catalyst causing the unconverted ethylene and propylene from the first-stage oligomerization reactor to dimerize and trimerize while higher olefins also dimerize, trimerize and tetramerize to provide distillate range olefins. With regard to the second-stage oligomerization reactor, process conditions are selected to produce a higher percentage of jet range olefins which, when hydrogenated in the hydrogenation reactor 14, result in a desirable jet-range hydrocarbon product. A predominance of the unconverted ethylene from the first-stage oligomerization reactor is dimerized, trimerized and tetramerized. In an embodiment, at least 99 wt % of ethylene in the second-stage oligomerization charge stream is converted to mostly butenes. The outlet stream 22 contains C4-C25 olefins.

[0035] The preferred second-stage oligomerization catalyst comprises an amorphous silica-alumina support. One of the components of the catalyst support utilized in the present invention is alumina. The alumina may be any of the various hydrous aluminum oxides or alumina gels such as alpha-alumina monohydrate of the boehmite or pseudo-boehmite structure, alpha-alumina trihydrate of the gibbsite structure, beta-alumina trihydrate of the bayerite structure, and the like. A particularly preferred alumina is available from Sasol North America Alumina Product Group under the trademark CATAPAL. This material is an extremely high purity alpha-alumina monohydrate (pseudo-boehmite) which after calcination at a high temperature has been shown to yield a high purity gamma-alumina. Another component of the catalyst support is an amorphous silica-alumina. A suitable silica-alumina with a silica-to-alumina ratio of 2.6 is available from CCIC, a subsidiary of JGC, Japan.

[0036] The second-stage oligomerization catalyst can be regenerated upon deactivation. Suitable regeneration conditions include subjecting the catalyst, for example, in situ, to hot air at about 400 to about 500° C. for 3 hours. To facilitate regeneration without downtime, a swing bed arrangement may be employed with an alternative second-stage oligomerization reactor. The regeneration gas may comprise air with an increased or decreased concentration of oxygen.

[0037] Downstream of the oligomerization reactors 12, an olefin splitter column 24 has an inlet 26 in communication with the outlet stream 22 and produces a bottoms outlet stream 28 and an overhead outlet stream 30. The bottoms stream 28 contains C8+ olefins and is fed to the hydrogenation reactor 14 at a temperature from about 160° C. (320° F.) to about 190° C. (374° F.) and a pressure of about 3.9 MPa(g) (550 psig) to about 7 MPa(g) (1000 psig). The overhead stream 30 contains C4-C8 olefins. The overhead stream 30 is recycled to the oligomerization reactors 12. The olefins splitter column 24 is operated at a bottom temperature of about 232° C. (450° F.) to about 316° C. (600° F.) and an overhead pressure of about 207 kPa(g) (30 psig) to about 689 kPa(g) (100 psig). The overhead stream 30 is mixed with the incoming olefin feed stream 23 to form a combined input stream.

[0038] The hydrogenation reactor 14 having an inlet 32 is in downstream communication with the bottoms stream 28. The hydrogenation reactor 14 is charged with hydrogen gas H2 (not shown), that first mixes with input stream 28 of C8+ olefins to form a combined input stream. The combined stream is charged to the hydrogenation reactor 14 to saturate the olefinic bonds to provide an output stream 34 of C8+ paraffins. The bottoms stream 28 is charged to the hydrogenation reactor 14 at 125° C. (257° F.) to about 204° C. (400° F.) and 3.5 MPa (g) (500 psig) to about 6.9 MPa(g) (1000 psig). An excess of hydrogen may be employed to ensure complete saturation. The H2:olefin ratio in the hydrogenation reactor 14 may be from about 1.5 to about 2.5.

[0039] The hydrogenation reactor 14 uses a conventional hydrogenation or hydrotreating catalyst, and can include metallic catalysts containing, e.g., palladium, rhodium, nickel, ruthenium, platinum, rhenium, cobalt, molybdenum, or combinations thereof, and the supported versions thereof. Catalyst supports can be any solid, inert substance including, but not limited to, oxides such as silica, alumina, titania, calcium carbonate, barium sulfate, and carbons. The catalyst support can be in the form of powder, granules, pellets, or the like.

[0040] The jet fractionation column 16 having an inlet 36 is in downstream communication with the outlet stream 34 of the hydrogenation reactor 14. A reformed stream in line 66 is added to the hydrogenated outlet stream 34 before feeding the jet fractionation column 16. The jet fractionation column 16 separates the reformed stream and the hydrogenated outlet stream to produce a bottoms stream 40, an overhead stream 42, a first side outlet stream 44, and a second side outlet stream 46. The bottoms stream 40 contains C18+ paraffins. The jet fractionation column 16 separates the hydrocarbon inputs into various hydrocarbons. The jet fractionation column 16 may be operated at a bottoms temperature of about 288° C. (550° F.) to about 382° C. (720° F.) and an overhead absolute pressure of about 0 kPa (0 psia) to about 342 kPa (35 psia).

[0041] The bottoms stream 40 is split into two streams—a first bottoms stream 48 and a second bottoms stream 50. The first bottoms stream 48 is charged to a downstream diesel fractionator 52. The second bottoms stream 50 is mixed with the olefins stream 23 prior to being charged to the oligomerization reactor 12 to act as a recycle oil or diluent to absorb the exotherm in the oligomerization reactor 12. The ratio of the amounts of the second bottoms stream 50 and the olefins stream 23 is by weight from about 10:90 to about 90:10, more preferably from about 20:80 to about 70:30, and most preferably from about 20:80 to about 40:60.

[0042] The overhead stream 42 contains C7− paraffins that are cooled and fed to a jet fractionation receiver 54. The receiver 54 separates a fuel gas stream 56 from a naphtha stream 58. The fuel gas stream 56 is fed to the fuel gas header or further processed. The naphtha stream 58 is divided into two portions with a first portion 61 charged to the downstream reformer reactor 18 and a reformer feed portion 59 collected as a product. The ratio of the amounts of stream 59 to the hydrogenation effluent stream 34 is by weight from about 0.1 to about 15, more preferably from about 1 to about 10, and most preferably from about 2 to about 8.

[0043] The first side outlet stream 44 contains C12-C18 paraffins and after mixing with stream 60 is collected in a tank (not shown) or is otherwise collected as a jet fuel product stream. The second side outlet stream 46 contains C8-C11 paraffins and C8-C11 aromatics and a portion thereof in line 60 is mixed with the first bottoms stream 44 as part of the jet fuel product and a second portion is charged through line 62 to the reformer reactor 18.

[0044] The reformer reactor 18 receives input through inlet 64 from the stream 61 comprising C6-C7 naphtha and the reformer feed stream 62 comprising C8-C11 paraffins and aromatics as described above. The naphtha reformer feed portion in line 61 and the reformer feed in line 62 are combined to provide a combined reformer feed in line 65. The reformer converts paraffinic materials to aromatics to produce a mixture containing C6-C11 paraffins with a higher concentration of C6-C11 aromatics. The reformed stream 66 is discharged from the reforming reactor 18 to mix with the hydrogenation reactor outlet stream 34.

[0045] In the reformer reactor 18, the reactants may contact the catalyst in individual reactors in either upflow, downflow, or radial flow fashion, with the radial flow mode being preferred. The catalyst is contained in a fixed-bed system or a moving-bed system with associated continuous catalyst regeneration. The preferred embodiment of the current invention is a fixed-bed system. Alternative approaches to reactivation of the catalyst are as follows:

[0046] Semi-regenerative: The entire unit is operated to maintain activity by gradually increasing temperature to maintain product octane number, finally shutting the unit down for catalyst regeneration and reactivation. Swing reactor or Cyclic: Individual reactors are individually isolated by manifolding arrangements. As the contained catalyst becomes deactivated, the catalyst in the isolated reactor is regenerated and reactivated while the other reactors remain on-stream. Continuous: Catalyst is continuously withdrawn from the reactors by means of a slowly moving bed, and the catalyst is regenerated and reactivated before being returned to the reactors. This system permits higher operating severity and maintains high catalyst activity by reactivating each catalyst particle over a period of a few days. Hybrid: Semi-regenerative and continuous reactors are contained in the same unit. Usually this is effected by adding a continuous reactor to an existing semi-regenerative process unit to provide for higher severity operation with improved selectivity. The preferred embodiment of the current invention is a “semi-regenerative” although the others are suitable.

[0047] Operating conditions used for the reforming process of the present invention include a pressure selected within the range of about 100 to about 7000 kPa (abs), with the preferred pressure being about 350 kPa to about 4250 kPa (abs). Particularly good results are obtained at low pressure, namely a pressure of about 350 to about 2500 kPa. Reforming conditions include a temperature in the range from about 315° to about 600° C. and preferably from about 425° to about 565° C. The initial selection of the temperature within this range is made primarily as a function of the desired aromatics content of the product reformate considering the characteristics of the charge stock and of the catalyst. Ordinarily, the temperature then is thereafter slowly increased during the run to compensate for the inevitable deactivation that occurs to provide a constant aromatics concentration in the product. Multiple reforming reactors may be employed with interstage heating between reactors or heating applied to each reactor.

[0048] Suitable catalysts include a dual-function catalyst having a multi-metallic, combination of two or more metal components in specified concentrations on the finished catalyst, and its use in hydrocarbon conversion with increased aromatics production. Catalysts having both a hydrogenation-dehydrogenation function and a cracking function should maximize the former and minimize the latter. The cracking function generally relates to an acid-action material of the porous, adsorptive, refractory-oxide type which is typically utilized as the support or carrier for a heavy-metal component, such as the Group VIII (IUPAC 8-10) metals, which primarily contribute the hydrogenation-dehydrogenation function. Other metals in combined or elemental form can influence one or both of the cracking and hydrogenation-dehydrogenation functions.

[0049] Catalytic reforming involves a number of competing processes or reaction sequences. These include dehydrogenation of cyclohexanes to aromatics, dehydroisomerization of alkylcyclopentanes to aromatics, dehydrocyclization of an acyclic hydrocarbon to aromatics, dealkylation of alkylbenzenes and isomerization of paraffins. Hydrocracking reactions which produce light paraffin gases have a deleterious effect on the yield of products boiling in the jet fuel range. Process improvements in catalytic reforming thus are targeted toward enhancing those reactions effecting a higher yield of the liquid products containing more 5 or more carbon atoms and minimizing those reactions affecting cracked products containing 4 or fewer carbon atoms.

[0050] Generally, it is desirable to have flexibility with catalyst functionality for reforming. In one exemplary reforming process, increasing the yield of one or more C5+ hydrocarbons, hydrogen, and aromatic yields is desired. Optionally, the acidity of the catalyst can be altered by adding a metal and / or other elements to the catalyst. Generally, modification of the acid function results in reduced cracking of the alkanes to C3 and C4 light ends allowing increased selectivity to the formation of aromatics. Modification of the metal function may also occur resulting in the reduction of alkane cracking to methane and ethane. There can also be a reduction in the dealkylation reactions of aromatics leaving heavier and more valuable C8+ aromatics.

[0051] Beside the yields, the activity of a catalyst may enable obtaining a commercially useful conversion level without employing additional quantities of catalyst or using excessively high temperatures, which can lead to undesired higher costs. Higher catalyst activity can also be utilized to process greater quantities of feed or to increase conversion, and therefore increase the production of valuable products.

[0052] Catalytic materials used for reforming paraffinic feeds more selectively towards aromatics can be achieved by tuning the material acidity. In one embodiment, the catalytic material comprises a refractory aluminum oxide support, a metal from the platinum group, such as Re, and a halogen element.

[0053] The reformed stream in line 66 and the hydrogenated stream in line 34 are together fed in line 35 to the jet fractionation column 16 as previously mentioned.

[0054] The diesel fractionator 52 separates the first bottoms stream in line 48 from the jet fractionation column 16 to produce two outlet streams—a first overhead stream in an overhead line 72 and a second bottoms stream in a bottoms line 74. The first overhead stream 72 contains diesel fuel and is collected as a diesel product. The second outlet stream 74 contains heavy oil which is collected as product and perhaps used as lube base stock or further processed in an FCC unit or a hydrocracking unit.

[0055] FIG. 2 shows a second embodiment 100 of an apparatus and process for producing jet fuel with increased aromatics content that differs from that of FIG. 1 in the ordering of some of the reactors. The second embodiment 100 has the reformer reactor 18 positioned to receive a stream of C8-C11 paraffins from the second side outlet stream 46 and produces a reformed stream 166 which is fed to a downstream splitter column 180. The splitter column 180 separates a bottoms outlet stream 182 containing C8-C11 paraffins and C8-C11 aromatics and is mixed with the second side outlet stream 44 comprising C12-C18 paraffins. The splitter 180 has an overhead outlet stream 184 that is cooled and fed to a receiver 186 that separates a fuel gas stream 188 from a naphtha stream 190. In a further embodiment, the naphtha in line 58 from the jet fractionator column overhead could be added to the reformer feed stream in line 46 to be reformed in the reforming reactor 18. The splitter column 180 operates at a bottom temperature of about 232° C. (450° F.) to about 316° C. (600° F.) and an overhead pressure of about 207 kPa (30 psig) to about 689 kPa (100 psig).

[0056] FIG. 3 shows a third embodiment 200 of an apparatus and process for producing jet fuel with an increased aromatics content that is like that of FIG. 1 with a few exceptions. The third embodiment utilizes an ethylbenzene alkylation reactor 219 to increase the carbon number of the reformed stream by recourse to an ethylene alkylation agent. The ethylbenzene alkylation reactor 219 is charged by an alkylating agent input line 220 of ethylene and the reformed stream in line 266 comprising C6-C11 paraffins and aromatics and produces an outlet stream 235 comprising C8-C13 aromatics and C6-C11 paraffins. The outlet stream 235 mixes with the hydrogenation reactor output stream 34 to form a combined stream 35. The combined stream 35 is fed to jet fractionation column 16 through inlet 36. Alkylation involves the transfer of an alkyl group from an alkylating agent to an aromatic substrate widely referred to as an electrophilic aromatic substitution reaction. In the alkylation reactor 219, C6-C11 alkylaromatics are produced by catalytically reacting the reformed stream 266 from the reformer reactor 18 with the alkylating agent in the presence of an alkylation catalyst at an alkylation temperature and alkylation pressure to produce an alkylated stream 235 comprising C8-C13 aromatics and C6-C11 paraffins. The alkylation reaction is conducted at a temperature where the thermodynamics are favorable. In an embodiment, the alkylation unit 219 may be operated at a temperature of about 149° C. to about 482° C. and a pressure of about 1000 kPa (10 bar) to 14000 kPa (140 bar). Weight hourly space velocity (WHSV) for the alkylation reactor may range from about 4 hr−1 to about 100 hr−1. Aromatics to alkylating agent ratio for the reactor may range from 1 to 15 mol ratio.

[0057] In an aspect, the alkylation catalyst may comprise one or more from the group comprising sulfuric acid, hydrofluoric acid, aluminum chloride, boron trifluoride, solid phosphoric acid, chlorided alumina, acidic alumina, aluminum phosphate, silica-alumina phosphate, amorphous silica-alumina, aluminosilicate, aluminosilicate zeolite, zirconia, sulfated zirconia, tungstated zirconia, tungsten carbide, molybdenum carbide, titania, sulfated carbon, phosphated carbon, phosphated silica, phosphated alumina, acidic resin, heteropolyacid, inorganic acid, and a combination of any two or more of the foregoing.

[0058] In one embodiment, the alkylation catalyst comprises an aluminosilicate zeolite. In one version, the alkylation catalyst further comprises a modifier selected from the group consisting of Ga, In, Zn, Fe, Mo, Ag, Au, Ni, P, Sc, Y, Ta, a lanthanide, and a combination of any two or more of the foregoing. In another version, the alkylation catalyst further comprises a metal selected from the group consisting of Cu, Ag, Au, Pt, Ni, Fe, Co, Ru, Zn, Cd, Ga, In, Rh, Pd, Ir, Re, Mn, Cr, Mo, W, Sn, Os, an alloy of any two or more of the foregoing, and a combination of any two or more of the foregoing.

[0059] In an embodiment, the alkylation catalyst may be selected from zeolite catalyst or ionic liquid catalyst. In an exemplary embodiment, the alkylation catalyst comprises a SAPO based catalyst.

[0060] FIG. 4 shows a fourth embodiment 300 of an apparatus for producing jet fuel with an increased aromatics content that is like that of FIG. 1 with a few exceptions.

[0061] Downstream of the hydrogenation reactor 18 is a stripper column 315 having an inlet stream 317 that is the combination of the hydrogenation reactor output stream 34 and the first outlet stream 66 from the reformer reactor 18. The stripper column 315 separates low fraction hydrocarbons from higher fraction hydrocarbons. The stripper column 315 produces an output stream 333 of C7 and C8 hydrocarbons which is fed to the jet fractionation column 316. The bottoms outlet stream 319 contains C9-C11 aromatics and C9+ paraffins and is separated into two portions 353 and 355. The stripper column operates at a bottom temperature of about 232° C. (450° F.) to about 371° C. (700° F.) and an overhead pressure of about 207 kPa (30 psig) to about 689 kPa (100 psig). The ratio of the amounts of the first portion 353 to the olefin feed 23 is by weight from about 10:90 to about 90:10, more preferably from about 20:80 to about 70:30, and most preferably from about 20:80 to about 60:40.

[0062] The first portion 353 is a diluent that is recycled back to the oligomerization reactor 12 and mixes with the olefins stream 23 to form a combined input stream. The diluent serves to absorb the exotherm. The second portion 355 is fed to an inlet 336 to the jet fractionation column 316.

[0063] The condenser (not shown) provides an overhead stream 329 containing fuel gas which is sent to a fuel gas header or further processed and a liquid outlet stream 321 containing naphtha and is divided into a first naphtha stream 325 and a second naphtha stream 327. The first naphtha stream 325 is collected as a product. The second naphtha stream 327 is charged to an inlet 364 to the reformer reactor 18.

[0064] The jet fractionation column 316 produces a bottoms stream 340, an overhead stream 342, and a first side outlet stream 344. The first side outlet stream 344 contains C12-C18 paraffins and is collected as a jet fuel product. The bottoms stream 340 contains C18+ paraffins which can be collected for use as a diesel product or charged to a diesel fuel fractionator as described above. The overhead stream 342 comprises C8-C11 paraffins and C8-C11 aromatics that is divided into a first overhead stream 343 and a second overhead stream 345.

[0065] The first overhead stream 343 is mixed with the side outlet stream 344 to provide a synthetic aviation fuel line 350. The second overhead stream 345 is mixed with the second naphtha stream 327 and charged to the reforming reactor 18.

[0066] Many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood within the scope of the appended claims the invention may be protected otherwise than as specifically described. The description in the present application should not be read as implying that any particular element, step, or function is an essential or critical element that must be included in the claim scope. The scope of patented subject matter is defined only by the allowed claims. Moreover, none of the claims invokes 35 U.S.C. § 112(f) with respect to any of the appended claims or claim elements unless the exact words “means for” or “step for” are explicitly used in the particular claim, followed by a participle phrase identifying a function. Use of terms such as (but not limited to) “mechanism,”“module,”“device,”“unit,”“component,”“element,”“member,”“apparatus,”“machine,”“vessel,” or “system,” within a claim is understood and intended to refer to structures known to those skilled in the relevant art, as further modified or enhanced by the features of the claims themselves, and is not intended to invoke 35 U.S.C. § 112(f).

[0067] While this disclosure has described certain embodiments and generally associated methods, alterations and permutations of these embodiments and methods will be apparent to those skilled in the art. Accordingly, the above description of example embodiments does not define or constrain this disclosure. Other changes, substitutions, and alterations are also possible without departing from the spirit and scope of this disclosure, as defined by the following claims.EXAMPLE

[0068] The following Example is presented to only illustrate one possible application of the invention and should not be used to limit the scope of the invention as described in the claims. Many other possible variations may occur within the span of the invention.Example 1

[0069] An olefin stream was fed to an oligomerization reactor to make an oligomer stream. The oligomer stream was fed to a hydrogenation reactor to make a paraffinic stream. The paraffinic stream was separated into a jet fuel stream and a reformer feed stream. The composition of the reformer feed stream can be found in Table 1.TABLE 1Reformer Feed Mass Composition (wt %)CarbonNo.ParaffinOlefinNaphtheneAromaticTotal10000020000030000040000050000060000070000081.9507.8209.77938.3300038.3310 14.3100014.3111+37.5900037.59Total92.1807.820100.00

[0070] The reformer feed was fed to a reformer reactor to produce the reformed stream with increased aromatics, as shown in Table 2.TABLE 2Reformed Stream Mass Composition (wt %)CarbonNo.ParaffinOlefinNaphtheneAromaticTotal11.890001.8923.970003.9735.370.01005.3746.700.03006.7355.100.05005.1565.190.060.030.385.6675.940.070.041.978.0183.690.050.0711.0114.8296.530.080.1217.7924.5110 1.8000.034.676.4911+1.1400.0414.1015.28Total47.310.330.3349.9297.89

[0071] The reformed stream was fed to a splitter to remove the components that are too light for Jet blending. The reformed jet cut was then combined with the jet fuel stream from the jet fractionator to form the final jet fuel blend.SPECIFIC EMBODIMENTS

[0072] While the following is described in conjunction with specific embodiments, it will be understood that this description is intended to illustrate and not limit the scope of the preceding description and the appended claims.

[0073] A first embodiment of the disclosure is a process for making jet fuel or jet fuel blend stock comprising oligomerizing an olefin stream to an oligomer stream; hydrogenating the oligomer stream to provide a paraffin stream; separating the paraffin stream to provide a jet fuel stream and a reformer feed stream; reforming the reformer feed stream to provide a reformed stream comprising an increased concentration of aromatics. An embodiment of the disclosure is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the olefin feed is ethylene. An embodiment of the disclosure is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the olefin feed consists of a mixture of olefinic species within the carbon number range of C2-C8. An embodiment of the disclosure is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph further comprising mixing the reformed stream with the paraffin stream. An embodiment of the disclosure is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph further comprising alkylating ethylene with aromatics in the reformer stream to provide an alkylated aromatics stream. An embodiment of the disclosure is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph further comprising mixing the alkylated aromatics stream with the paraffin stream. An embodiment of the disclosure is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph further comprising oligomerizing the olefins stream in a first stage and further oligomerizing a first stage oligomer stream in a second stage to provide the oligomer stream. An embodiment of the disclosure is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the first stage uses a zeolite-type catalyst, and the second stage uses an amorphous silica-alumina base with a metal from either Group VIIIB and / or Group VIB in the periodic table using Chemical Abstracts Service notations. An embodiment of the disclosure is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the first stage uses an amorphous silica-alumina base with a metal from either Group VIIIB and / or Group VIB in the periodic table using Chemical Abstracts Service notations catalyst and the second stage uses a zeolite-type. An embodiment of the disclosure is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the reformer feed stream comprises C6 to C11 paraffins. An embodiment of the disclosure is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph further providing a jet fractionation column having a first side outlet producing the jet fuel stream and a second side outlet producing the reformer stream. An embodiment of the disclosure is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph further comprising a splitter column to separate the reformed stream into a naphtha stream and a C8 to C11 hydrocarbon stream and further comprising mixing the C8 to C11 stream with the jet fuel stream. An embodiment of the disclosure is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the step of reforming utilizes a catalyst comprising a refractory aluminum oxide support, a platinum component, a germanium, a tin, or a rhenium component or a combination thereof, and a halogen component. An embodiment of the disclosure is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the step of reforming produces a hydrogen stream that is in communication with the hydrogenating step.

[0074] A second embodiment of the disclosure is an apparatus for making jet fuel comprising an oligomerization reactor having a first outlet stream; a hydrogenation reactor in communication with the first outlet stream and having a second outlet stream; a jet fractionation column in communication with the second outlet stream to separate the second outlet stream into a third outlet stream and a fourth outlet stream; and, a reformer reactor in communication with the third outlet stream to produce a fifth outlet stream with an increased aromatics content. An embodiment of the disclosure is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph further comprising an aromatics alkylation reactor in communication with the fourth outlet stream to form a sixth outlet stream. An embodiment of the disclosure is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph wherein the jet fractionation column has a first side outlet producing the third outlet stream and a second side outlet producing the fourth outlet stream.

[0075] A third embodiment of the disclosure is an apparatus for making jet fuel comprising an oligomerization reactor having a first stage for forming a first oligomer stream and a second stage in communication with the first oligomer stream to form a second oligomer stream; a hydrogenation reactor in communication with the second oligomer stream and having a hydrogenated hydrocarbon outlet stream; a fractionation column in communication with the hydrogenated hydrocarbon outlet stream to separate the hydrocarbon outlet stream into a jet fuel outlet stream and a reformer outlet stream; and, a reformer reactor in communication with the reformer outlet stream to produce a jet fuel stream with an increased aromatics content. An embodiment of the disclosure is one, any or all of prior embodiments in this paragraph up through the third embodiment in this paragraph further comprising an aromatics alkylation reactor in communication with the reformer outlet stream. An embodiment of the disclosure is one, any or all of prior embodiments in this paragraph up through the third embodiment in this paragraph wherein the fractionator column is a jet fractionator having a first side outlet and a second side outlet, the first side outlet produces the jet fuel outlet stream, and the second side outlet produces the reformer outlet stream.

[0076] Without further elaboration, it is believed that using the preceding description that one skilled in the art can utilize the present disclosure to its fullest extent and easily ascertain the essential characteristics of this disclosure, without departing from the spirit and scope thereof, to make various changes and modifications of the disclosure and to adapt it to various usages and conditions. The preceding preferred specific embodiments are, therefore, to be construed as merely illustrative, and not limiting the remainder of the disclosure in any way whatsoever, and that it is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims.

[0077] In the foregoing, all temperatures are set forth in degrees Celsius and, all parts and percentages are by weight, unless otherwise indicated.

Examples

example 1

[0069]An olefin stream was fed to an oligomerization reactor to make an oligomer stream. The oligomer stream was fed to a hydrogenation reactor to make a paraffinic stream. The paraffinic stream was separated into a jet fuel stream and a reformer feed stream. The composition of the reformer feed stream can be found in Table 1.

TABLE 1Reformer Feed Mass Composition (wt %)CarbonNo.ParaffinOlefinNaphtheneAromaticTotal10000020000030000040000050000060000070000081.9507.8209.77938.3300038.3310 14.3100014.3111+37.5900037.59Total92.1807.820100.00

[0070]The reformer feed was fed to a reformer reactor to produce the reformed stream with increased aromatics, as shown in Table 2.

TABLE 2Reformed Stream Mass Composition (wt %)CarbonNo.ParaffinOlefinNaphtheneAromaticTotal11.890001.8923.970003.9735.370.01005.3746.700.03006.7355.100.05005.1565.190.060.030.385.6675.940.070.041.978.0183.690.050.0711.0114.8296.530.080.1217.7924.5110 1.8000.034.676.4911+1.1400.0414.1015.28Total47.310.330.3349.9297.89

[0071]...

specific embodiments

[0072]While the following is described in conjunction with specific embodiments, it will be understood that this description is intended to illustrate and not limit the scope of the preceding description and the appended claims.

[0073]A first embodiment of the disclosure is a process for making jet fuel or jet fuel blend stock comprising oligomerizing an olefin stream to an oligomer stream; hydrogenating the oligomer stream to provide a paraffin stream; separating the paraffin stream to provide a jet fuel stream and a reformer feed stream; reforming the reformer feed stream to provide a reformed stream comprising an increased concentration of aromatics. An embodiment of the disclosure is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the olefin feed is ethylene. An embodiment of the disclosure is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the olefin ...

Claims

1. A process for making jet fuel or jet fuel blend stock comprising:oligomerizing an olefin stream to an oligomer stream;hydrogenating said oligomer stream to provide a paraffin stream;separating said paraffin stream to provide a jet fuel stream and a reformer feed stream;reforming said reformer feed stream to provide a reformed stream comprising an increased concentration of aromatics.

2. The process of claim 1 wherein the olefin feed is ethylene.

3. The process of claim 1 wherein the olefin feed consists of a mixture of olefinic species within the carbon number range of C2-C8.

4. The process of claim 1 further comprising mixing said reformed stream with said paraffin stream.

5. The process of claim 1 further comprising alkylating ethylene with aromatics in said reformer stream to provide an alkylated aromatics stream.

6. The process of claim 5 further comprising mixing said alkylated aromatics stream with said paraffin stream.

7. The process of claim 1 further comprising oligomerizing said olefins stream in a first stage and further oligomerizing a first stage oligomer stream in a second stage to provide said oligomer stream.

8. The process of claim 7 wherein the first stage uses a zeolite-type catalyst, and the second stage uses an amorphous silica-alumina base with a metal from either Group VIIIB and / or Group VIB in the periodic table using Chemical Abstracts Service notations.

9. The process of claim 7 wherein the first stage uses an amorphous silica-alumina base with a metal from either Group VIIIB and / or Group VIB in the periodic table using Chemical Abstracts Service notations catalyst and the second stage uses a zeolite-type.

10. The process of claim 1 wherein said reformer feed stream comprises C6 to C11 paraffins.

11. The process of claim 1 further providing a jet fractionation column having a first side outlet producing the jet fuel stream and a second side outlet producing the reformer stream.

12. The process of claim 1 further comprising a splitter column to separate the reformed stream into a naphtha stream and a C8 to C11 hydrocarbon stream and further comprising mixing the C8 to C11 stream with the jet fuel stream.

13. The process of claim 1 wherein the step of reforming utilizes a catalyst comprising a refractory aluminum oxide support, a platinum component, a germanium, a tin, or a rhenium component or a combination thereof, and a halogen component.

14. The process of claim 1 wherein the step of reforming produces a hydrogen stream that is in communication with the hydrogenating step.

15. An apparatus for making jet fuel comprising:an oligomerization reactor having a first outlet stream;a hydrogenation reactor in communication with the first outlet stream and having a second outlet stream;a jet fractionation column in communication with the second outlet stream to separate the second outlet stream into a third outlet stream and a fourth outlet stream; and,a reformer reactor in communication with the third outlet stream to produce a fifth outlet stream with an increased aromatics content.

16. The apparatus of claim 15 further comprising an aromatics alkylation reactor in communication with the fourth outlet stream to form a sixth outlet stream.

17. The apparatus of claim 15 wherein the jet fractionation column has a first side outlet producing the third outlet stream and a second side outlet producing the fourth outlet stream.

18. An apparatus for making jet fuel comprising:an oligomerization reactor having a first stage for forming a first oligomer stream and a second stage in communication with the first oligomer stream to form a second oligomer stream;a hydrogenation reactor in communication with the second oligomer stream and having a hydrogenated hydrocarbon outlet stream;a fractionation column in communication with the hydrogenated hydrocarbon outlet stream to separate the hydrocarbon outlet stream into a jet fuel outlet stream and a reformer outlet stream; and,a reformer reactor in communication with the reformer outlet stream to produce a jet fuel stream with an increased aromatics content.

19. The apparatus of claim 18 further comprising an aromatics alkylation reactor in communication with the reformer outlet stream.

20. The apparatus of claim 18 wherein the fractionator column is a jet fractionator having a first side outlet and a second side outlet, the first side outlet produces the jet fuel outlet stream, and the second side outlet produces the reformer outlet stream.

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