JP2010523807A - Fischer-Tropsch jet fuel method - Google Patents

Abstract

The present invention is a method for refining a Fischer-Tropsch jet fuel having a jet fuel yield of more than 60% by mass, comprising the following five conversion processes: a. FT kerosene and heavier mass fraction, and C9 or higher FT synthetic crude oil Process for hydrocracking one or more fractions; b. Process for oligomerizing FT synthetic crude oil fractions containing hydrocarbons in the C2 to C8 range; c. Production from FT synthetic crude oil fraction, process b. And a process of hydrotreating one or more alkylated FT synthetic crude oil fractions; d. FT synthetic crude oil fractions containing hydrocarbons ranging from C2 to C8, products from process a., Process b. A process for aromatizing one or more of the product from the process, the product from the process c., And the product from the aromatic alkylation process; and e. FT synthetic crude oil comprising hydrocarbons ranging from C2 to C6 From distillate, product from process b., And from process d. A process comprising at least four of alkylating one or more of the products of:
[Selection] Figure 1

Description

[Field of the Invention]
The present invention relates to a method for producing jet fuel from synthetic crude produced by the Fischer-Tropsch process.

[Background of the invention]
Have mainly hydrogen (H ₂₎ and synthesis gas which is a mixture of gases containing carbon monoxide (CO) (syngas (syngas)) Fischer-Tropsch for the production of synthetic hydrocarbons from (FT) synthesis is used for a long period It was.
FT synthesis is a chemical reaction performed on a metal oxide catalyst, and its active metals include iron (Fe), cobalt (Co), ruthenium (Ru), and nickel (Ni). These catalysts can be produced by precipitation or supported on a metal oxide such as alumina, titania, zirconia, magnesia or the like.
The main reaction of FT synthesis can be described as follows.
2H ₂ + CO →-[CH ₂ ]-+ H ₂ O
During this reaction,-[CH ₂ ]-represents the main component of the paraffinic hydrocarbon and is sometimes called an alkane.

This process is generally carried out at high temperatures in the range of 200-400 ° C. and high pressures up to 40 bar-g. Perform this process in many reactor designs such as (i) annular fixed bed, (ii) three phase slurry bed (aka bubble column), (iii) hot circulating bed, and (iv) two phase fluidized bed. Can do. These have been extensively described in research literature such as the Fischer-Tropsch Technology book (Elsevier, 2004) edited by AP Steynberg and ME Dry.
This reaction proceeds by a mechanism known to those skilled in the art as chain propagation. The above reaction is repeated many times to produce long chain species of up to 100 carbon atoms. The products of this synthesis are often described in the art as primary FT products, and at ambient conditions FT hydrocarbon gases (C2-C4), FT liquid products (C5-C21) and solid FT products ( Includes a very wide distillation range including C22 and higher). This blend is also described as synthetic crude or syncrude in many publications such as "Processing of Fischer-Tropsch Syncrude and Benefits of Integrating its Products with Conventional Fuels" (NPRA Paper AM-00-51, 2000). ing.
The main product of FT synthesis or synthetic crude oil can be separated into various liquid streams with processing conditions in the C3 to C5 range, naphtha C6 to C8 range and C9 and higher ranges, for example.
Fuel refineries produce product slate that may generally contain kerosene cuts regardless of whether crude oil, Fischer-Tropsch synthetic crude oil, coal liquefied oil, oil shale or tar sands are refined. To do.
The most common purification route for producing jet fuel (Jet A-1) from materials in the kerosene range is by hydroprocessing. It may be desirable to produce more kerosene range material to ultimately enhance jet fuel production, for example US Pat. No. 4,409,092 suggests doing this.

More recently, the US Department of Defense has expressed interest in space fuels from military applications, preferably from synthetic methods to improve energy security (Forest, et al. 2005). This so-called Battlefield Use Fuel of the Future (BUFF) is very similar in specification to jet fuel but has a stricter flash point standard (60 ° C, similar to JP-5). ). Ideally, the synthetic fuel refinery should produce only kerosene range materials. Conceptually, a “jet fuel only” refinery can be devised, but the yield of substances in the kerosene range actually obtained is limited. Even conversion processes that are well known in the art to be very kerosene selective, such as the conversion of propylene on solid phosphoric acid (Junes 1954), do not produce exclusively substances in the kerosene range.
Straight run Fischer-Tropsch products have several inherent disadvantages to meet Jet A-1 and / or BUFF specifications: high linearity resulting in high freezing point and low temperature viscosity and low aromatic content. In addition, the Anderson-Schultz-Flory distribution, often used to describe the carbon number distribution of Fischer-Tropsch products, is a straight-run synthesis of the kerosene range, regardless of the Fischer-Tropsch method. This indicates that the amount of crude oil is limited. Using the Anderson-Schulz-Flory description, straight-run kerosene from the Fischer-Tropsch process is preferably obtained by tailoring the Fischer-Tropsch catalyst so that the chain growth probability coefficient (α value) is in the range of 0.76 to 0.86. It can be seen that manufacturing can be optimized. Many current commercial Fischer-Tropsch technologies operate outside this range, high-temperature Fischer-Tropsch (HTFT) technologies operate at alpha values below 0.7, and low-temperature Fischer-Tropsch (LTFT) technologies are generally higher than 0.9 Operates with α value. However, even with the Fischer-Tropsch conversion process optimized for the production of materials in the kerosene range, the direct yield of kerosene is less than 30%. Nevertheless, the synthesis of jet fuel components from Fischer-Tropsch products and methods of blending them to produce semi-synthetic jet fuels and fully synthetic jet fuels are well known in the art.

In this text, kerosene may be understood as a fraction having a carbon number range of C9 to C16, typically having a boiling range of 149 ° C to 288 ° C, although variations in this definition may exist.
When distilled from the product of a low temperature Fischer-Tropsch (FLFT) hydrocracker preparing Jet A-1 C ₈ ~C ₁₃ fraction is reduced, this is met most of Jet A-1 standard, Jet Contains less aromatics than the required 8% aromatics of A-1.
The initial boiling point of this material is limited by the flash point specification of jet fuel, and the final boiling point is limited by the Jet A-1 standard (up to 300 ° C). In practice, however, a lower final boiling point is often required to meet the freezing point specification (up to -47 ° C). It has also been pointed out that problems may arise due to the low temperature viscosity of kerosene range materials obtained from low temperature Fischer-Tropsch (LTFT) synthetic crude oil (Lamprecht 2006).
Shell's LTFT hydrocracking unit design makes 50% of the LTFT synthetic crude in the kerosene range of materials as used commercially at its gas-to-liquids facility in Bintulu, Malaysia Although it has a maximum kerosene mode of operation that can be repeatedly purified, the naphtha and distillate products from the operation are only blended components and are not transportation fuels that meet the specifications for motor gasoline and diesel fuel.
Preparation of Jet A-1 from isoparaffin kerosene by oligomerization of short chain olefins on high temperature Fischer-Tropsch (HTFT) hydrogenated straight kerosene and solid phosphoric acid (SPA) meets all specifications including density Unfortunately, the amount that can be produced is limited.

What is needed is a synthetic fuel facility that can maximize kerosene yield so that kerosene meets Jet A-1 / JP-8 and / or JP-5 / BUFF standards.
Recognize that kerosene, which can easily purify by-product naphtha and distillate, must meet final fuel specifications rather than having to sell it as naphtha or distillate blend stock. Has been. This is particularly relevant when the refinery is remote from the market for such intermediate products or when the refinery is used as a strategic asset for the production of military fuel.

According to a first embodiment of the present invention, a method for purifying a Fischer-Tropsch jet fuel having a jet fuel yield of more than 60% by mass, comprising the following five conversion processes:
-A. Hydrocracking one or more FT kerosene and heavier material fractions and one or more C9 or higher FT synthetic crude oil fractions;
-B. A process for oligomerizing FT synthetic crude oil fractions containing hydrocarbons ranging from C2 to C8;
A process for hydrotreating one or more of the FT synthetic crude oil fraction, the product from process b., And the alkylated FT synthetic crude oil fraction;
-From FT synthetic crude oil fractions containing hydrocarbons ranging from C2 to C8, product from process a., Product from process b., Product from process c., And aromatic alkylation process A process for aromatizing one or more of the products of; and -e. A FT synthetic crude light concentrate fraction containing hydrocarbons in the range C2-C6, the product from process b., And from process d. There is provided a method comprising at least four of the processes of alkylating one or more of the products.

The yield can exceed 70%.
Oligomerization process b. Includes oligomerizing a C3 to C8 FT synthetic crude oil fraction.
The oligomerization process b. Includes the step of oligomerizing a C6 to C8 FT synthetic crude oil fraction.
Aromatization process d. Includes oligomerizing a C3 to C8 FT synthetic crude oil fraction.
The alkylation process e. Includes alkylating a C2 FT synthetic crude oil fraction, preferably an ethylene FT synthetic crude oil fraction.
Alkylation process e. Includes alkylating a C3-C6 FT synthetic crude oil fraction.
When process b. Is performed using a SPA catalyst, conversion process b. And conversion process e. May be combined.
In one embodiment, process d. And process e. May be combined.
The oligomerization process b. Can be selected to oligomerize the FT concentrate to kerosene range hydrocarbons while maintaining and / or imparting low temperature fluidity.
The FT concentrate may include FT hydrocarbon gas and FT naphtha.
The FT concentrate may contain hydrocarbons ranging from C3 to C8.
Hydrotreatment process c. Can be selected to remove olefins and further remove oxygenates to produce kerosene.
Hydrotreating process c. Includes the step of hydrotreating a C6-C8 FT synthetic crude naphtha fraction.
The aromatization process d. Can be selected to produce an aromatic compound and produce little octane.
The aromatization process can convert naphtha from hydrocracking process a.
Select aromatization process d., H _2, can be generated benzene, toluene, ethylbenzene, xylene, and the aromatic compound of kerosene range.
The aromatization process d. Can be selected to avoid the by-production of dinuclear aromatic compounds, such as naphthalene, that would adversely affect the smoke point of kerosene range materials.
The alkylation process e. Can be selected to increase the polyalkylation of aromatics with ethylene to produce aromatics in the kerosene boiling range while simultaneously reducing ethylene in the product.
The alkylation process e. Can be selected to reduce polyalkylation of aromatics with olefins to maximize production of alkyl aromatics in the kerosene boiling range.
A process of hydrocracking under hydrocracking conditions in a hydrocracking zone containing a hydrocracking catalyst can be performed / performed.
The oligomerization step can be performed / performed in the oligomerization zone containing the oligomerization catalyst under oligomerization conditions.
The step of hydrotreating under hydrotreating conditions in the hydrotreating zone containing the hydrotreating catalyst can be implemented / performed.
The step of aromatization under aromatization conditions can be carried out / performed in an aromatization zone containing an aromatization catalyst.
The step of alkylating under alkylation conditions in the alkylation zone containing the alkylation catalyst can be performed / performed.
Examples of purification techniques typically considered for the present invention include the following techniques.

The above method is capable of co-manufacturing chemicals and / or other oil phase fuels that can meet fuel standards such as Euro-4, while producing a total synthetic jet fuel that meets the international jet A-1 standard in a high yield. It is believed that a refinery with reduced complexity can be provided.
Such refineries can overcome some of the limitations imposed by straight distillation yield, high linearity (high freezing point) and low aromatic content.
Depending on the technology type and the order of the conversion units, the amount of conforming jet fuel and the quality of other products can be improved. Because this is itself flexible, it is a further advantage of the present invention, allows for a secondary product and can accommodate the adoption of different purification techniques.

It is a flow sheet of a method optimized to produce the largest amount of kerosene range material from Fischer-Tropsch synthetic crude oil. 2 is a flow sheet designed by the jet fuel refinery of Example 1. 2 is a flow sheet designed by a jet fuel refinery of Example 2. 4 is a flow sheet designed by a jet fuel refinery of Example 3. 6 is a flow sheet designed by the jet fuel refinery of Example 4.

Detailed Description of the Invention
The present invention will now be described by way of non-limiting example only with reference to the accompanying flow sheet.
The present invention can be illustrated as the method of FIG. 1 optimized to produce the largest amount of kerosene range material from a Fischer-Tropsch synthetic crude. FT synthetic crude oils typically can have the following composition:

The method of FIG. 1 utilizes a combination of only the following conversion processes: hydrocracking (unit [a]), oligomerization (unit [b]), hydrotreating (unit [c]), aromatization ( Unit [d]) and alkylation (unit [e]).
Substances in the kerosene range can also be used as a BUFF if necessary, as long as they meet the international Jet A1 standard and meet the stricter flash point standards of BUFF by adapting the separation process.
The first conversion unit of the process of FIG. 1 is unit [a], and the hydrocracking occurs partly under hydroisomerization conditions and partly under hydrocracking conditions. Hydrocracking is known in the art for the production of kerosene from synthetic crude oil. As is well known in the art, the catalyst used for this conversion is bifunctional and contains acid sites and metal sites. Its application within the present invention differs from that known in the art as far as feed composition and unit structure are concerned.

Olefin oligomerization is the second conversion unit, unit [b], and is known in the art for producing materials in the kerosene range from lighter olefin materials. The choice of oligomerization catalyst has a significant impact on product distribution and properties. In this invention, the preferred embodiment is an oligomerization process based on either a solid phosphoric acid (SPA) catalyst or an amorphous silica-alumina (ASA) catalyst, although the invention is limited to these types. Or is not limited. The feedstock can consist of hydrocarbon gas, typically a C ₂ -C ₅ stream 3a as well as naphtha, typically a C5 or higher material stream 3b. Feedstock pretreatment is not necessary, but should be noted with the inherent limitations of the catalyst selected. For example, a mixture of hydrocarbons and oxygenates typical of Fischer-Tropsch synthetic crude oil can be supplied to the ASA, but SPA is not very resistant to oxygenates. This conversion process involves three main products: light hydrocarbons, typically C ₂ -C ₈ stream 4a, kerosene, typically C ₉ -C ₁₄ stream 4b, and distillate, typically C ₁₅ There is the above stream 4c. The ratio and composition of these products depends on the type of oligomerization process. For example, selecting SPA catalyst will eliminate the production of C ₁₅ or more distillate streams 4c. Internal recycling can also be used to optimize the quality and yield of the desired product. Other aspects of this conversion process taught in the art are also included, such as thermal management by recirculation of paraffin.

Since the oligomerization process is not suitable for paraffin conversion, olefinic naphtha and lighter products can be recycled to eliminate stream 4a, but the paraffin in this stream does not disappear. Whether the paraffin in stream 4a is considered as the final product (eg C3-C4 product can be used as LGP or fuel gas and C5 + product can be used as naphtha) or as feed for aromatization unit [d] can do. Further, it is not essential to recycle until the olefin in the stream 4a disappears. Olefin-containing mixtures can also be used as final products, for example, C3-C4 product as LPG or fuel gas, C5 + product as naphtha, alkylation as feed for aromatization unit [d] Could be used as feed to unit [e] or hydroprocessing unit [c].
The kerosene product stream 4b from the oligomerization can be hydrogenated in the hydrotreater unit [c] to improve storage stability.
The distillate product stream 4c from the oligomerization can be hydrocracked by feeding it by internal recycle of the hydrocracking unit [a]. By feeding the distillate product stream 4c by internal recycle of the hydrocracker, excess cracking is limited and kerosene yield is improved. The preferred embodiment of the present invention first sends distillate stream 4c to hydrotreater unit [c] and then uses it as feed stream 5c to hydrocracker unit [a]. This is done to further reduce excessive degradation and increase kerosene yield.
The third conversion unit is a hydrotreating unit [c], which is used to increase the storage stability of kerosene and meet standards related to oxygenated compounds such as acid value. In processes such as the aromatization unit [d], if the selected aromatization technique requires some pretreatment of the feedstock, it will also be pretreated. As is well known in the art, the catalyst used is a metal promoted hydroprocessing catalyst. Although its use in the present invention differs from that described in the art, feed streams 3b, 4a, 4b and 4c are unique feed mixtures of olefin oligomers and straight-run Fischer-Tropsch synthetic crude oil. Configure. The product from this conversion process is typically of the same structure as the feedstock, but oxygenates and olefins have been converted to paraffin. The three main products are distinguished on the basis of the distillation range: gas and naphtha, typically C ₃ -C ₈ stream 5a, kerosene, typically C ₉ -C ₁₄ stream 5b and distillate, typically The stream 5c is C ₁₅ or higher. Other aspects of this conversion process taught in the art such as co-feeding of hydrogen are also included.

The gas and naphtha product stream 5a can be used as a final product such as motor-gasoline or as a feed for the aromatization unit [d]. The preferred application will depend on the type of aromatization technique selected, the type of oligomerization technique used and the composition of the product, ie oligomers and / or straight-run Fischer-Tropsch synthetic crude oil. The product is a mixture of hydrotreated FT synthetic crude and oligomers from [b]. However, the composition depends on the specific flow scheme used.
Kerosene product stream 5b, also known as isoparaffinic kerosene (IPK), is known in the art as an excellent component for jet fuel.
The distillate product stream 5c can be used as a feed to the hydrocracker unit [a] to improve the kerosene yield as already described.

The fourth conversion unit is an aromatization unit [d]. This process supplies the hydrogen consumption process detailed in the present invention while producing the aromatics necessary to meet jet fuel specifications. The composition of the feed to this unit stream 2a, 4a and / or 5a depends on the choice of aromatization technology and two main types of technology are famous.
The first type of aromatization process is naphtha aromatization, which requires a feedstock in the naphtha range (C6 and above). A preferred embodiment of the present invention utilizes an aromatization process based on non-acidic Pt / L zeolite, a type of naphtha aromatization that is highly suitable for the conversion of Fischer-Tropsch feedstock. Standard catalytic reforming methods based on platinum promoted alumina chloride catalysts can also be used, but are not very effective in this application. This can be seen in terms of feedstock characteristics, while non-acidic Pt / L zeolite methods prefer linear hydrocarbons (Fischer-Tropsch synthetic crude oil is rich in linear hydrocarbons), but Pt-alumina methods are naphthenic ( Prefer feedstock rich in cyclo-paraffins). In both cases, the feedstock must be pretreated to remove heteroatoms, which is done during hydrocracking unit [a] and hydrotreating unit [b].
Aromatization process of the second type is an aromatization of light hydrocarbons, can convert the feedstock comprising C ₃ and higher hydrocarbons. This type of aromatization process is based on a metal-promoted H-ZSM-5 zeolite catalyst, with the metals Ga and Zn being the most used. Although this conversion can also be achieved with an unpromoted H-ZSM-5 catalyst, it is not a preferred embodiment because a metal is required for the desorption of hydrogen as molecular hydrogen. The process based on ZSM-5 is highly resistant to heteroatom compounds in the feedstock such as oxygenates and can use the feedstock without prior hydrotreatment of stream 4a. However, it is known in the art that oxygenates are detrimental to catalyst life and the choice of feedstock and / or combination of raw stream 4a and pretreated stream 2a and / or stream 5a feedstock. Can be considered.

The type of aromatization process determines not only the feed requirements but also the product structure, and different processes have different product structures. The aromatization process naphtha, because not be converted to aromatics by recycling any of the C ₅ following hydrocarbons formed during the said process, is considered a fatal conversion to the product. Conversely, in the light hydrocarbon aromatization process, C ₃ or higher hydrocarbons can be recycled to improve the yield of aromatic compounds. Despite these differences, the three main product fractions are light gas, typically hydrogen and C ₁ -C ₂ hydrocarbon stream 6a, gas and light naphtha, typically C ₃ -C ₆ carbonization. naphtha hydrogen-rich stream 6b and aromatic compounds, typically C ₆ or more aromatic compounds with C ₇ and higher hydrocarbons stream 6c is produced during the aromatization. Other feedstocks and product streams known in the art are also included.
The light gas stream 6a is a product rich in hydrogen. This is an excellent source of hydrogen and can be recovered by processes well known in the art such as pressure swing adsorption. Depending on the process and product structure, this may provide sufficient hydrogen for the conversion process of the hydrocracking unit [a] and the hydroprocessing unit [c]. Excess hydrogen can be exported to the Fischer-Tropsch gas loop to increase the yield of synthetic crude oil. Depending on the nature of the Fischer-Tropsch technology, a gas with less hydrogen can be used as a fuel gas or as a feedstock for synthesis gas production.
The composition of the gas and light naphtha stream 6b depends on the aromatization process. In the case of naphtha aromatization, stream 6b is very paraffinic and can be used as a final product as a liquid petroleum gas for compounding gas and / or fuel gas. Although it is technically possible to recycle this product, it can hardly be recycled. If a light naphtha aromatization process is selected, this product can be recycled until it disappears, or depending on its olefin content, it can be passed to the oligomerization unit [b] or the alkylation unit [e]. You can also send it.

The naphtha stream 6c rich in aromatic compounds is a source of aromatic compounds necessary to meet the aromatic standards of jet fuel. Although a portion of this product can be used directly as the final fuel, preferred embodiments of the present invention send at least a portion of this product to the alkylation process unit [e].
The aromatic compounds produced during aromatization in unit [d] are mainly in the range of C ₆ -C ₉ aromatics. Not all aromatic compounds can be incorporated directly into kerosene because the flash point of jet fuel will be too low. This drawback is overcome by alkylating aromatics with olefins in the alkylation process unit [e] to increase the average molecular weight of the aromatics. The composition of the olefin and aromatic feedstock components, and the type and operation of the alkylation process are selected to maximize the production of aromatics in the kerosene range.
Aromatic feed stream 6c can be pre-fractionated to increase the C ₆ -C ₈ aromatic fraction in the feed, but this is not a requirement. Where appropriate, olefin feed can be derived directly from the Fischer-Tropsch hydrocarbon gas stream 3a, the olefin-containing light hydrocarbons from the oligomerization stream 4a and the olefin-containing gas and naphtha products from the aromatization stream 6b. These feeds can be selected by any suitable combination.

In a preferred embodiment of the invention, the olefin oligomerization unit [b] and aromatic alkylation unit [e] processes are combined into a single process. This reduces the number of conversion units required in the present invention from 5 to 4. However, this preferred embodiment limits the choice of catalyst to that taught in the art. If alkylation is performed separately from oligomerization, the catalyst selection for this process can be expanded to include catalyst types such as zeolites. In a further possible embodiment of the present invention, the alkylation is performed separately, but in such a way that the alkylation unit also performs some oligomerization to ease the load on the oligomerization unit.
Although the alkylation process can be operated such that the alkylation process primarily produces kerosene product stream 7b, some low boiling material may form stream 7a. As taught in the art, this requires maximizing the production of kerosene, including some recycling or transalkylation steps of the product. Depending on the level of oligomerization in this unit, it may be necessary to hydrotreat the olefin in the kerosene cut in the hydrotreater unit [c] before using kerosene for jet fuel. Other feedstocks and product streams known in the art are also included. A portion of this kerosene product may be blended with other fuel products or used as a final product such as cumene.

The following examples illustrate the invention but should not be construed as limiting the invention in any way.
Example 1. As shown in FIG. 2, the jet fuel refinery design of this example is based on feedstock from HTFT. The purpose of this example is to show how much jet fuel can be produced from Fischer-Tropsch synthetic crude oil using the present invention.
C ₉ or more synthetic crude oil Fischer-Tropsch (boiling point typically> 130 ° C.) was used as feed stream 1 to the hydrocracker unit [a], operating as described in the present invention. Products from the olefin oligomerization stream 4c in the distillate range above C ₁₆ (boiling point typically> 280 ° C.) are first hydrotreated to produce stream 5c and then hydrocracked. This results mainly in kerosene stream 2b with a yield of about 75% based on fresh feedstock. The C ₃ -C ₈ light hydrocarbon stream 2a is sent to the aromatization unit [d].
Fischer-Tropsch C ₆ -C ₈ synthetic crude oil (boiling range typically 40-130 ° C.) is used as feed stream 3b to oligomerization unit [b] without pretreatment. The oligomerization process uses an ASA catalyst that can handle the oxygenates present in this feedstock. The hydrocarbon stream 4a of C ₈ or less produced during the oligomerization is sent to the aromatization unit. C ₉ and heavier hydrocarbon product streams 4b and 4c are hydrotreated in unit [c] to a saturated product of isomorphic structure. The hydrotreater unit [c] also hydrotreats the kerosene range mixture of the oligomerization and alkylation product stream 7b from the alkylation unit [e] to saturate the olefin, resulting in a stable storage of the resulting product. Improve sexiness. The product stream 5b in the kerosene range is a jet fuel component, but the distillate stream 5c is sent to the hydrocracker unit [a] as already described.
The aromatization unit [d] is based on a process using a metal promoted H-ZSM-5 catalyst. The feed streams to this unit are C ₃ -C ₈ hydrocarbons from hydrocracker stream 2a, C ₅ -C ₈ hydrocarbons from oligomerization stream 4a and C ₃ -C ₄ from alkylation stream 7a. Composed of hydrocarbons. Operate the aromatization unit with internal recycle to convert C ₃ -C ₆ hydrocarbons (boiling point lower than benzene). The light gas stream 6a is used as a source of refinery hydrogen. The naphtha fraction (the boiling range of benzene to xylene) was sent to the alkylated stream 6b, while the heavier aromatic fraction in the kerosene boiling range is used as the jet fuel component stream 6c.
The C ₆ -C ₈ aromatics contained in the product from the aromatization stream 6b are alkylated with an olefin rich Fischer-Tropsch C ₃ -C ₅ feed stream 3a. A combined alkylation oligomerization process based on SPA catalysts is used to not only alkylate aromatic compounds, but also oligomerize excess olefins to kerosene. The C ₅ -C ₈ product stream 7a _ii is retained as the final naphtha and forms part of what is termed “fatal naphtha formation” to avoid accumulation of inert substances in the refinery recycle stream. , C ₃ -C ₄ cut stream 7a _i is recycled back to the aromatization unit [d]. The kerosene range product stream 7b is hydrotreated to saturate the olefin prior to use as a jet fuel component.

This refinery design resulted in an 11:89 naphtha: kerosene split that met the requirements of a fully synthetic Jet A1. Naphtha is low in aromatics but high in olefins and needs to be further refined for use as a transportation fuel. A summary of possible streams is shown in Table 1 and is reported based on all Fischer-Tropsch synthetic crude oil of 500000 kg / h (excluding water gas shift gas). The refinery design shown in this example does not show the processing steps for Fischer-Tropsch C ₁ -C ₂ hydrocarbons or oxygenates dissolved in the aqueous product from the Fischer-Tropsch synthesis. Chemicals such as ethylene, ethanol, acetone, isopropanol, n-propanol and methyl ethyl ketone can be recovered from these fractions by methods well known in the art. C _{3 and} higher oxygenates can be converted to olefins and treated with other FT C ₃ -C ₅ feed streams 3a to increase jet fuel production based on the same Fischer-Tropsch feed .

Table 1. Overview of the stream shown in FIG. 2 of the first embodiment

Example 2 The jet fuel refinery design shown in this example and in FIG. 3 is based on the same feed as in Example 1. There are differences in the choice of oligomerization, aromatization and alkylation processes. The purpose of this example is to show that the present invention can also meet the naphtha motor-gasoline standard (Euro-4) while maximizing the production of jet fuel. A further objective of this example is to demonstrate how integration of Fischer-Tropsch aqueous product work-up is beneficial.
Hydrocracker unit to operate in accordance with the present invention [a] converts the Fischer-Tropsch C ₉ or more synthetic crude oil stream 1 to the product stream 2a lighter kerosene stream 2b. Only the C ₆ -C ₈ cut stream 2a _ii is sent to the aromatization unit [d], and the C ₃ -C ₅ cut stream 2a _i is sent to the oligomerization unit [b] as a thermal management diluent. used.
Combining oligomerization and alkylation conversion in a single unit [b / e] by utilizing a SPA catalyst operated in an olefin-rich conversion mode. This eliminates the need for a separate alkylation unit. Feed stream to this unit Fischer-Tropsch C ₃ -C ₅ fraction stream 3a, C ₃ -C ₅ fractions from the hydrocracker stream 2a _i, benzene and Fischer from aromatisation unit stream 6b _i Olefin stream from Tropsch aqueous product refiner stream 8. Olefin from the aqueous product purification device typically as described previously in the art, is produced by the dehydration of selective hydrogenation and C ₃ or more alcohol olefin alcohols to carbonyl compounds . During this mixed process of olefin oligomerization and aromatic alkylation, benzene is converted primarily to cumene and heavier aromatics are formed to a lesser extent. This does not interfere with the normal oligomerization process. The products from this process are C ₃ -C ₄ liquid petroleum gas stream 4a _i , unhydrogenated C ₄ -C ₈ motor-gasoline stream 4a _ii , and naphtha stream 4a _iii and kerosene stream 4b fractions, hydrogen Sent to the processor unit [c]. The nature of the conversion on SPA catalysts is such that very little material is produced heavier than kerosene, and it is customary in the art to remove these products with a small bottom purge stream. ing.
The hydrotreater unit [c] removes the olefins and oxygenates present in the F Fischer-Tropsch C ₆ -C ₈ naphtha stream 3b and the products from the mixed oligomerization-alkylation unit streams 4a _iii and 4b. Hydrogenate. Hydrogenation may be performed in a single unit, but the feed and product points should be separated so that Fischer-Tropsch naphtha does not mix with the oligomerization product. This allows the unit to use a more optimal catalyst packing diagram and enhances the overall quality of the final product. The hydrotreatment may be performed in a separate reactor. Although hydrogenated kerosene stream 5b is a jet fuel component, oligomerization product stream 5a _i of hydrogenated naphtha range motor - a gasoline component. Hydrogenated Fischer-Tropsch C ₆ -C ₈ naphtha stream 5a _ii is used as feed to the aromatization unit [d].
The aromatization unit [d] is based on a non-acidic Pt / L-zeolite catalytic process. The feedstock is C ₆ -C ₈ range naphtha obtained from hydrocracking stream 2a _ii and hydrotreating stream 5a _ii . This process has a high yield of hydrogen and aromatics. Hydrogen is recovered from the light gas stream 6a and exceeds the requirements of the hydrocracking and hydroprocessing units [a] and [c]. This hydrogen can be exported to the Fischer-Tropsch gas loop, which has a beneficial effect on synthetic crude yield. This potential benefit is recognized but not demonstrated in this example. The naphtha product is separated to produce a benzene stream 6b _i , a liquid petroleum gas fraction stream 6b _ii and an aromatic gasoline stream 6b _iii . This type of aromatization process is a process in which the production of kerosene is determined by the feedstock, and in this particular example no kerosene forming material was used as the feedstock.
The refinery in this example is a 28:72 motor-gasoline: jet fuel product split after purification including ethanol from Fischer-Tropsch aqueous products to meet the 10% Fuel Oxygen Directive. Brought about. The calculated motor-gasoline and jet fuel characteristics are shown in Table 2.

Table 2. Characteristics of motor-gasoline and jet fuel calculated for Example 2 shown in FIG.

A summary of possible streams is shown in Table 3 and is reported based on all Fischer-Tropsch synthetic crude oil of 500000 kg / h (excluding water gas shift gas). This example does not show a Fischer-Tropsch C ₁ -C ₂ hydrocarbon treatment process. From this example, chemicals such as ethylene can be recovered and the remainder sold as synthetic natural gas or used as fuel gas. This example essentially includes a purification step for oxygenates dissolved in the aqueous product from the Fischer-Tropsch synthesis, with ethanol being purified as a motor-gasoline additive, with heavier alcohols and all carbonyls. The compound is converted to olefin.

Table 3. Overview of the stream shown in FIG. 3 of the second embodiment

Example 3 FIG. The jet fuel refinery design of Example 2 was modified by changing the method of carrying out the aromatic alkylation. In this example, as shown in FIG. 4, an individual alkylation unit based on a zeolite catalyst is used and operated to recycle the monoalkylated aromatic compound to increase the yield of dialkylated aromatic compound. . Furthermore, the overall yield of motor-gasoline and jet fuel based on the same feedstock as in Example 2 without ethylene being selected when alkylating the olefins and significantly changing the motor-gasoline to jet fuel ratio. Strengthened.
The feedstock, operation and products from the hydrocracker unit [a] are the same as in Example 2.
An oligomerization unit [b] similar to Example 2 is based on a process utilizing a SPA catalyst. The feedstock is the same as in Example 2, the only difference being that no aromatic compound is fed to this unit. Thus, the product is low in alkyl aromatics but mainly consists of aliphatic hydrocarbons. The product is divided into different distillation fractions: C ₃ -C ₄ liquid petroleum gas stream 4a _i , unhydrogenated C ₄ -C ₈ motor-gasoline stream 4a _ii , and naphtha stream 4a _iii and kerosene stream 4b fractions. To the hydrotreater unit [c].
The hydrotreater unit [c] is the same as in Example 2, but the composition of some streams is different. This difference is particularly noticeable in kerosene feed stream 4b, which is low in alkyl aromatics.
The aromatization process unit [d] is identical in terms of feedstock, operation and product. Differ only in the delivery of the benzene fraction stream 6b _i, benzene fraction stream 6b _i is sent to the alkylation unit [e].

In this example, the alkylation unit [e] is based on ethylene alkylation of benzene over a zeolite catalyst such as H-ZSM-22. The main differences from the commercial practice of ethylbenzene production are the use of an ethylene / ethene mixture from Fischer-Tropsch as feed stream 9 in addition to benzene stream 6b _i and recycling the monoalkylated benzene with benzene Is to increase the yield. The main products are kerosene range aromatics stream 7b, aromatic naphtha stream 7a _ii and C ₂ rich fuel gas stream 7a _i .
A summary of possible streams is shown in Table 4 and is reported based on a total Fischer-Tropsch synthetic crude oil of 500000 kg / h (excluding water gas shift gas). The context description is the same as in Example 2, but this example includes a Fischer-Tropsch C ₂ hydrocarbon treatment step. Despite the similar motor-gasoline: jet fuel product split at 28:72, slightly improved fuel properties were obtained compared to Example 2.

Table 4. Overview of the stream shown in FIG. 4 of the third embodiment

Example 4 The jet fuel refinery design in this example (FIG. 5) is based on a feedstock from an LTFT process with similar synthetic crude properties that are commercially operated in South Africa by Sasol, Sasolburg. The principle can be extended to the Oryx GTL facility in Qatar and the Shell Bintulu GTL facility in Malaysia. The purpose of this example is that, despite the considerable difference in Fischer-Tropsch carbon number distribution and composition between HTFT and LTFT synthetic crudes, the present invention is applicable to both and depends on the α value of the Fischer-Tropsch catalyst. It is to show that there is no limit. (Thus, a mixture of synthetic crude oils with different carbon number distributions can be considered as a feedstock).
The hydrocracker (FIG. 5, unit [a]) is operated according to the description of the present invention. The main feed to this unit is the C ₉ or higher fraction from the low temperature Fischer-Tropsch synthesis (Figure 5, Feed 1). In contrast to the HTFT feed, the LTFT feed to this unit contains a significant (> 50%) “residue” or paraffin wax fraction. The hydrotreated C ₁₆ or higher fraction from olefin oligomerization (FIG. 5, stream 5c) is also fed to the hydrocracker. The two main products from this unit are C ₃ -C ₈ light hydrocarbons (FIG. 5, stream 2a), as feed for aromatization (FIG. 5, unit [d]) and final jet fuel components. Is used as kerosene (FIG. 5, stream 2b).

C _{3 and} higher hydrocarbons are separated from the LTFT product gas under pressure without the need for cryogenic cooling. The C ₄ -C ₈ fraction (FIG. 5, stream 3b) is used as feed to the oligomerization unit (FIG. 5, unit [b]). The oligomerization process uses an ASA catalyst that can handle the oxygenates present in this feedstock. Light products consisting of some light olefins and most C ₄ paraffins (Figure 5, stream 4a _i ) can be used as liquefied petroleum gas (LPG), motor-gasoline blending components, or aromatization units (Figure 5, Unit [d]). In this embodiment, it is used as LPG. The naphtha product, which is a mixture of C ₅ -C ₈ olefin and paraffin (FIG. 5, stream 4a _ii ) can be hydrogenated or used directly as olefin naphtha, as in this example. It may be used as a feed to the aromatization unit. Kerosene (FIG. 5, stream 4b) and heavier distillate (FIG. 5, stream 4c) are hydrotreated in an olefin hydrotreating unit (FIG. 5, unit [c]). Hydrotreated kerosene (Fig. 5, stream 5b) is the final jet fuel component, and hydrotreated distillate (Fig. 5, stream 5c) is hydrocracking unit (Fig. 5, unit [a]) Used as a feedstock.
The aromatization unit (FIG. 5, unit [d]) is based on the metal-promoted H-ZSM-5 catalytic process. The feed to this unit consists of C ₃ -C ₈ hydrocarbons from the hydrocracker (FIG. 5, stream 2a). It was noticed that the use of naphtha from oligomerization (FIG. 5, stream 4a) as a feed could further increase aromatic formation, but this was not done in this example. The aromatization unit is operated using internal recycle to convert C ₃ -C ₆ hydrocarbons (boiling point lower than benzene), but single flow operation is also conceivable. Hydrogen can be recovered from the light gas (FIG. 2, stream 6a), and the remainder of the light gas can be used as fuel gas. The heavier product is fractionated and applied in various ways. The fraction containing all of the benzene and toluene (FIG. 5, stream 6b _i ) is used as an aromatic feed for the alkylation unit (FIG. 5, unit [e]). The fraction containing the remainder of toluene and a portion of the C ₈ aromatics is retained as naphtha (FIG. 5, stream 6b _ii ), and the heavier kerosene fraction is used as the jet fuel component (FIG. 5, stream 6b). _iii ).

Aromatic alkylation (5, unit [a]) is performed using the LTFT C ₃ cuts rich in propylene. As is well known in the art, this unit is operated in an alkylation mode with internal recycling of aromatics to limit oligomerization as a side reaction. The technique used can be based on solid phosphoric acid (SPA) or a zeolite catalyst. In this example, polyalkylation was limited using SPA-based techniques. The products from this unit are light gases, typically propane rich (Fig. 5, stream 7a _i ), naphtha (Fig. 5, stream 7a _ii ) and aromatic kerosene (Fig. 5, stream 7b). Kerosene is the final jet fuel component and can optionally be hydrogen finished to improve storage stability.
A summary of possible streams is shown in Table 5 and is reported based on a total Fischer-Tropsch synthetic crude oil of 500000 kg / h (excluding water gas shift gas). This example does not show the processing steps for Fischer-Tropsch C ₁ -C ₂ hydrocarbons and oxygenates dissolved in the aqueous product. The product split of motor-gasoline: jet fuel is 21:79. Jet fuels meet Jet A1 standards, but motor-gasoline is very aromatic and cannot be considered a final transportation fuel.

Table 5. Overview of the stream shown in FIG. 5 of the fourth embodiment

Claims (10)

A method for purifying a Fischer-Tropsch jet fuel having a jet fuel yield of more than 60% by mass, comprising the following five conversion processes:
-A. Hydrocracking one or more FT kerosene and heavier material fractions and one or more C9 or higher FT synthetic crude oil fractions;
-B. A process for oligomerizing FT synthetic crude oil fractions containing hydrocarbons ranging from C2 to C8;
A process for hydrotreating one or more of the FT synthetic crude oil fraction, the product from process b., And the alkylated FT synthetic crude oil fraction;
-From FT synthetic crude oil fractions containing hydrocarbons ranging from C2 to C8, product from process a., Product from process b., Product from process c., And aromatic alkylation process A process for aromatizing one or more of the products of; and -e. An FT synthetic crude oil fraction comprising hydrocarbons in the range C2-C6, the product from process b., And the product from process d. A process comprising at least four of the processes of alkylating one or more of the above.   The process according to claim 1, wherein the conversion process b. And the conversion process e. Are combined when the process b. Is carried out using a SPA catalyst.   The method of claim 1, wherein process d. And process e. Are combined.   4. The oligomerization process b. Is selected to oligomerize C3-C8 FT synthetic crude oil fractions to kerosene range hydrocarbons while maintaining and / or imparting low temperature fluidity. 2. The method according to item 1.   The method according to any one of claims 1 to 4, wherein the hydrotreating process c. Removes olefins and further removes oxygenates to produce kerosene.   6. The method of any one of claims 1-5, wherein the aromatization process d. Is selected to produce an aromatic compound and produce little octane.   The method of claim 6, wherein the aromatization process d. Converts naphtha from hydrocracking process a. The aromatization process d. Is, H _2, benzene, to produce toluene, ethylbenzene, xylene, and the aromatic compound of the kerosene range, method according to claim 6 or 7.   9. The method of claim 8, wherein the aromatization process d. Avoids by-product of dinuclear aromatic compounds.   10. The alkylation process e. Increases the polyalkylation of aromatics with ethylene to produce aromatics in the boiling range of kerosene and simultaneously reduces ethylene in the product. The method described in 1.

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