JP2004292813A - Transporting synthetic fuel and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transporting fuel which is obtained from the Fischer-Tropsch synthesis and which contains none of oxygen-containing compounds, sulfur and other heteroatom compounds, and to provide a method for manufacturing a blend stock therefor. <P>SOLUTION: The fuel is a hydrocarbon mixture and comprises a hydrocarbon mixture containing an around 8C-around 20<SB>+</SB>C olefin/paraffin mixture, and the olefin/paraffin mixture contains approximately 1 mass %-20 mass % of the olefins, and which contains substantially no oxygen-containing compounds and at least approximately 1 mass % of which is monoolefins, at least approximately 5 mass % of n-paraffins, and contains approximately 2-94 mass % of branched paraffins, in which at least approximately 30 mass % of the all branched groups is monomethyl and a ratio of the end branched monomethyl to the internal branched monomethyl is at least approximately 1:1.5. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for the production of a transport fuel obtained from the product of the Fischer-Tropsch synthesis, or a blend stock for a transport fuel. More particularly, the present invention relates to a method in which oxygenates are converted by a selective low cost method. The present invention further relates to transport fuels having high cetane number, high lubricity, high stability and substantially free of oxygenated compounds, sulfur and other heteroatom compounds, or blend stocks therefor. It relates to a manufacturing method.

  Demand for synthetic transportation fuels is increasing because they do not contain sulfur or aromatic compounds and usually have a high cetane number. However, the Fischer-Tropsch process used to produce fuels for synthetic transportation results in synthetic crude oil products containing oxygenates (FT oxygenates). FT oxygenates typically contain aldehydes, ketones, and acids in addition to primary and internal alcohols that make up the majority of the FT oxygenates. The presence of FT oxygenates presents several problems in the production of synthetic crude oils, including adverse effects on hydrogenation catalysts that necessitate increasing the severity of the hydrogenation process. Increasing the severity of the hydrogenation process increases yield loss. As used herein, the term "hydroprocessing" refers to "hydrocracking," "hydroisomerization," "hydrodewaxing," or a combination of two or more of these processes. Say.

  Also, the FT oxygenates can be removed through hydrotreatment. However, hydroprocessing requires significant additional capital investment. The FT oxygenates content is generally higher in the low boiling fraction of the Fischer-Tropsch product and drops sharply beyond the 600 ° F. (316 ° C.) cut point. One way to avoid the adverse effects of the FT oxygenates on the hydrocracking catalyst is to divert the low boiling fraction around the hydrocracking unit. Thereafter, the lower boiling fraction containing the FT oxygenates is remixed with the hydrocracked higher boiling fraction to form product fuel. The diverted 250-400 ° F. (121-204 ° C.) fraction has little adverse effect when remixed with product fuel, but the diverted 400 ° F. + (204 ° C. or higher) Recombining of the fractions impairs the low temperature properties of the product fuel due to the presence of FT oxygenates. Therefore, typically, the hydrogen for the entire 400 ° F + (204 ° C or higher) fraction will adversely affect the life of the hydroprocessing catalyst and include hydrogenation of the FT oxygenates causing yield loss. Perform the conversion process. Noble metal catalytic hydrogenation process catalysts are well known and some of them are described in U.S. Patent Nos. 3,852,207; 4,157,294; Is hereby incorporated by this reference. Hydrogenation processes utilizing non-noble metals such as rhenium, zirconium, hafnium, cerium or uranium-activated cobalt catalysts to make a mixture of paraffins and olefins have also been used. However, as mentioned above, a hydrogenation process under harsh conditions increases the cost of the process and the resulting product, and also leads to a loss of yield.

  Therefore, an improved integrated Fischer-Tropsch process that can remove all or some of the FT oxygenates at lower cost than known hydrogenation process means and with substantially no loss of yield. is needed. Furthermore, transportation fuels or blends thereof that are substantially free of sulfur, FT oxygenates and other heteroatom compounds, have high lubricity and high stability, and can be produced economically Stock is needed.

  The present invention satisfies these needs by providing a transportation fuel or blend stock for a transportation fuel that is substantially free of FT oxygenates, sulfur and other heteroatoms. The present invention further removes oxygenates and improves lubricity and low temperature properties, while not causing economical, significant yield loss, or known hydroprocessing and hydrotreatment. It is an object of the present invention to provide a method for producing a transportation fuel or a blend stock for a transportation fuel, which has a significantly lower yield loss than the method.

In one embodiment of the present invention, at least about 5% by weight of n-paraffin, from about 11% to about 20% by weight of olefin, and less than 50% of all branching groups in the molecule are monomethyl, of which Having a ratio of terminal monomethyl branch groups to internal monomethyl branch groups of at least 1: 1.5, and having about 2% to about 90% by weight of branched paraffins, and substantially having FT oxygenates. not, the range of carbon atoms is from about C _{7 ~} about C _24, synthetic fuel containing a hydrocarbon mixture is provided.

  In another embodiment of the present invention, (a) producing a light Fischer-Tropsch solution; (b) dehydrating all or a portion of the FT oxygenates in the LFTL while maintaining the olefin content in the LFTL. (C) recovering the dehydrated product; (d) separating the aqueous layer and the organic layer of the dehydrated product; and (e) mixing the organic layer of the dehydrated product with the transportation fuel. A method for producing a synthetic fuel is provided.

  Further aspects and advantages of the present invention will become apparent with reference to the drawings, description of forms, and claims.

  This application claims priority based on US patent application Ser. No. 60 / 455,224, which is hereby incorporated by reference in its entirety.

In the term “C _x ”, x is a number greater than zero and C _x refers to a hydrocarbon compound whose main component is x carbon atoms. Further, the term C _x, for example, as the C ₅ olefin, sometimes used by being deformed to describe a special hydrocarbons. In this example, the term refers to an olefin stream that is pentene-based and may have less than about 10% as an impurity of an olefin having another carbon number, such as hexene, heptene, propene, butene, and the like. Say. Similarly, the term “C _{x +} ” refers to a stream that is primarily composed of hydrocarbons with carbon numbers greater than or equal to x and may also contain hydrocarbons with carbon numbers less than x at impurity levels. For example, the term C ₁₅₊ means a hydrocarbon having 15 or more carbon atoms, which may also include hydrocarbons having less than 15 carbon atoms at impurity levels. In the term “C _x -C _y ”, x and y are numbers greater than zero, and C _x -C _y refers to a total of about 90% or more by mass of the main component hydrocarbons between x and y Is a mixture of hydrocarbon compounds having the number of carbon atoms. For example, the term C ₅ -C ₉ hydrocarbon, a hydrocarbon having a carbon number of from 5 to 9 as a main component, may also include hydrocarbons having other number of carbon atoms in the impurity level amounts of hydrocarbon compounds Means a mixture.

  The term "high lubricity" as used herein was tested in accordance with ASTM standard D-6079-02, entitled "Standard Test Method for Evaluating Diesel Fuel Lubricity with High Speed Piston Rig". It means that the wear scar diameter has an average diameter of about ≦ 0.46 mm at 60 ° C. "High Stability" and "High Oxidation Stability" are tested in accordance with ASTM Standard D-22-74-01 titled "Standard Test Methods for Oxidation Stability of Distillate Oil Fuels (Accelerated Method)". Means the total solids content is ≦ 1.5 mg / 100 ml. It should be noted that these test methods are specifically for investigating petroleum-derived products, but for the analysis and characterization of synthetic products, these test methods were applied here.

  Unless otherwise indicated, all amounts, percentages and ratios herein are by weight.

  The Fischer-Tropsch process involves the treatment of synthesis gas to produce a hydrocarbon stream by the Fischer-Tropsch reaction, recovery of the Fischer-Tropsch product, catalytic dehydration of all or part of the Fischer-Tropsch product, and carbonization by phase separation. Recovery of hydrogen. The Fischer-Tropsch synthesis described in U.S. Pat. Nos. 4,973,453; 6,172,124; 6,169,120; 6,130,259 is particularly useful for the production method of the present invention. And these disclosures are all incorporated by reference.

A Fischer-Tropsch conversion system for converting a hydrocarbon gas into a liquid or solid hydrocarbon product using a self-heating reforming reaction includes a synthesis gas unit, which includes a nickel-containing catalyst. And a synthesis gas reactor of the type of an autothermal reforming reactor (ATR) containing a reforming catalyst such as Including natural gas, light hydrocarbon stream to be converted is placed in the reactor together and oxygen (O _2). Oxygen is supplied from compressed air or other compressed oxygenated gas. Alternatively, the supplied oxygen may be a pure oxygen stream. The ATR reaction is adiabatic and no heat is added or removed from the reactor except for heat from the feed and heat of reaction. The reaction is performed under sub-stoichiometric conditions such that the oxygen / stream / gas mixture is converted to synthesis gas.

Primarily Fisher for converting synthesis gas comprising carbon monoxide (CO) and hydrogen gas (H ₂₎ - Tropsch reactions are characterized by the general reaction below:
2nH ₂ + nCO → (−CH ₂ −) _n + nH ₂ O (1)

  Non-reactive components such as nitrogen may also be included or mixed in the synthesis gas. This occurs when air, enriched air, or other impure oxygen sources are used in syngas formation.

Syngas is delivered to a syngas unit that includes a Fischer-Tropsch reactor (FTR) containing a Fischer-Tropsch catalyst. Various Fischer-Tropsch catalysts are used to carry out the reaction. These include cobalt, iron, ruthenium, other VIIIB transition metals, or combinations of these metals, to make saturated and unsaturated hydrocarbons. The Fischer-Tropsch catalyst may include a support such as a metal oxide support such as silica, alumina, silica-alumina, or titanium oxide. For example, a Co catalyst on transition alumina having a surface area of about 100 to about 200 m ² / g is used in particulate form with a diameter of about 50 to about 150 μm. The Co concentration on the support is about 15% to about 30% by mass. Specific catalyst promoters and stabilizers may be used. Stabilizers include Group IIA or IIIB metals, and accelerators include Group VIII or VIIB elements. Fischer-Tropsch catalysts and reaction conditions are selected to be optimal for the desired reaction product, such as a hydrocarbon of a particular chain length or number of carbon atoms. For the Fischer-Tropsch synthesis, any of a fixed bed, a slurry bed reactor, a boiling bed, a fluidized bed, and a continuous stirred tank reactor (CSTR) may be used. The FTR operates at a pressure of about 100 psia (690 kPa) to about 500 psia (3448 kPa) and a temperature of about 375 ° F (190 ° C) to about 500 ° F (260 ° C). The gas hourly space velocity (GHSV) of the reactor is from about 1000 to about 8000 hr ^-1 . Useful Fisher present invention - useful syngas to produce Tropsch product comprises gaseous hydrocarbons, hydrogen, carbon monoxide, nitrogen, the ratio of H 2 _/ CO is about 1.8: 1 to about 2.4: 1. Fischer - hydrocarbon products resulting from Tropsch reaction may vary from methane (CH ₄₎ to high molecular weight paraffin wax containing carbon atoms in excess of 100.

  Turning to FIG. 1, an overview of the Fischer-Tropsch process is illustrated. The synthesis gas produced in ATR 11 is transferred to Fischer-Tropsch reactor (FTR) 2 through line 1. The tail gas of the Fischer-Tropsch product is collected overhead in line 3 and the Fischer-Tropsch oil and wax are fractionated and collected via lines 4 and 5, respectively. The product recovered in line 4 is light Fischer-Tropsch liquid (LFTL), and the product recovered in line 5 is heavy Fischer-Tropsch liquid (HFTL).

  The LFTL cut contains from about 2% to about 15% isoparaffin. Virtually all isoparaffins are terminal monomethyl species. In the present invention, the terminal species are 2- and 3-methyl branches. The ratio of terminal monomethyl to internal monomethyl branches in LFTL paraffin is about 1: 1.5, 1: 1, 1.5: 1, 2: 1 or more. As mentioned earlier, all percentages herein are by weight.

All or part of the LFTL mainly consisting of C ₂ to C ₂₄ hydrocarbons is sent to the dehydration unit 6. In the dehydration unit 6, the primary or internal alcohol present in the LFTL, that is, the FT oxygen-containing compound, is dehydrated to a corresponding olefin. A detailed study of the dehydration process is entitled "Integrated Fischer-Tropsch Method with Improved Oxygenated Compound Treatment Capacity", provisional application number 60 / 455,224, and Amen Abbazadian et al. No. 10 / 426,154, the disclosure of which is incorporated herein by reference. Alternatively, LFTL is distilled prior to dehydration in order to isolate the _C 8 _{-C 20+ min,} C _{8 -C 20+} fraction is placed then dehydrated unit 6.

  The dehydration product generated in the dehydration unit 6 is collected and concentrated. The concentrated product comprises an aqueous layer and an organic layer, which can be separated using a suitable means such as phase separation. Since alcohol is substantially completely dehydrated, both the organic layer and the aqueous layer are basically free of alcohol. The organic layer contains predominantly paraffins along with some olefins, which originate not only from Fischer-Tropsch products but also from the dehydration of alcohols.

The organic layer is transferred to fractionation tower 8. HFTL from FTR 2 is also transferred to fractionation tower 8 via conduit 5. Naphtha is withdrawn _overhead from fractionation tower 8 via conduit 13 and the C ₈₊ fraction is transferred to hydrocracking / hydrotreating unit 10 where it is cracked to low molecular weight hydrocarbons.

  The hydrocracked product produced in the hydrocracking / hydrotreating unit 10 is transferred to a second fractionation unit 12, where the boiling range is from about 250 ° F (121 ° C) to about 700 ° F ( 371 ° C.) is collected via conduit 14. All or part of the middle distillate is used as a transportation fuel or a blend stock therefor.

  FIG. 2 illustrates another form of the integrated Fischer-Tropsch method. LFTL and HFTL are mixed in the distillation column 30 and fractionated. The product having a temperature of 30 ° F. (−1 ° C.) to 600 ° F. (316 ° C.) has a 30 ° F. (−1 ° C.) to 250 ° F. (121 ° C.) cut through line 32, a temperature of 250 ° F. 121 ° C.) to 500 ° F. (260 ° C.) fraction through line 34, and a temperature of 500 ° F. + (260 ° C. +) fraction through line 35, which is removed as one or more side streams. Then, only the 250 ° F (121 ° C) to 500 ° F (260 ° C) fraction is sent to the dehydration unit 6. The 250 ° F. (121 ° C.) to 500 ° F. (260 ° C.) fraction, collected and fractionated after dehydration, is sent through conduit 33 to product storage and / or mixing unit 37.

  FIG. 1 illustrates that a mixture of dehydrated products of paraffins and olefins is also sent to a hydrocracking / hydrotreating unit 10 which is suitable when a fully hydrotreated product is desired. ing. However, the mixture of dehydrated products can also be hydroisomerized separately. In another form, the mixture of dehydrated products may be free from any post-dehydration hydrogenation. FIG. 3 shows one possible hydrocracking / hydroisomerization configuration. However, any number of alternative post-dewatering and high boiling region fraction treatment modes can be employed in the integrated Fischer-Tropsch process, depending on the desired product. For example, referring to FIG. 3, another processing scheme includes:

a) Hydroisomerization of the dehydrated product; hydrocracking of the 500 ° F + (260 ° C +) cut followed by hydrotreatment.
b) No post-dehydration treatment of the dehydrated product; hydrocracking of 500 ° F + fraction.
c) No post-dehydration treatment of dehydration products; hydrocracking followed by hydrocracking of 500 ° F + fraction.
d) hydroisomerization of the dehydrated product; 500 ° F. + no fraction hydrogenation process; fractionation following remixing of the dehydrated-hydroisomerized product with 500 ° F. + fraction; hydrogen in fractionated bottom stream Decomposition.
e) hydroisomerization of the dehydrated product; hydrocracking of the 500 ° F. + fraction.
f) No post-dehydration treatment of dehydration products; hydrocracking followed by hydrotreatment of 500 ° F + fraction.
g) No post-dehydration treatment of dehydration product; hydrogenation of 500 ° F. + fraction.
h) No post-dehydration treatment of dehydrated product; hydrotreatment, hydrocracking, hydrorefining of 500 ° F + fraction.
i) No post-dehydration treatment of the dehydrated product; hydrotreating and hydrocracking of the 500 ° F + fraction; hydrodewaxing of the unconverted hydrocracker bottom stream and hydrorefining of the lubricating oil basestock.
j) No post-dehydration treatment of dehydration products; hydrocracking of 500 ° F. + fraction; hydrogenation of unconverted wax.

  These alternative processing schemes are only some of the forms that are included and useful in the Fischer-Tropsch process of the present invention. Accordingly, the above list and FIG. 3 are merely illustrative of a portion of the Fischer-Tropsch method of the present invention and are not intended to be limiting. Possible process conditions and parameters for the hydroisomerization, hydrotreating and hydrocracking of the relevant hydrocarbon stream are those well known in the art. One example of hydrogenation process conditions and parameters is described in U.S. Patent Nos. 5,286,455, 6,296,757, 6,180,842, the disclosures of which are incorporated herein by reference. Included by. Many other hydrogenation process conditions and parameters are also well known in the art, but they are also useful with the integrated Fischer-Tropsch process described herein. Accordingly, the inclusion of the above-referenced U.S. patents is not limiting of the method of the present invention.

  Process modes (a), (b), (c), (d), (e), (f), and (j) are most useful for producing ultraclean synthetic middle distillate fuels. The product of the integrated Fischer-Tropsch process is used as a direct transportation fuel or as a blend stock to form a transportation fuel. Further, to produce an olefin / paraffin mixture as a dehydration product used as a feed for a single product middle distillate feedstock, the processes (b), (c), (f), (G), (h), (i) and (j) are the most useful. It should be noted that if the dehydration product does not undergo a hydroprocessing or hydrotreating, the olefins produced in the Fischer-Tropsch reaction will remain in the middle distillate and be charged to the synthetic transport fuel.

  The middle distillate of the dehydrated LFTL contains only relatively low levels, i.e., about 2% to about 10% by weight, and substantially no all of them contain branched paraffins that are monomethyl branches, so the middle distillate Minutes alone are not normally used as transportation fuels. That is, a high proportion of normal paraffins produces cloud and freezing points that prevent the incorporation of higher molecular weight paraffins. Most diesel fuels and virtually all jet fuels require mixing with hydrocracked HFTL fractions. As the hydrocracking process produces more branched paraffins, the hydrocracked HFTL fraction generally lowers the cloud point and freezing point of the final blended fuel. In fact, hydrocracked HFTL contains a significant proportion of highly methyl-branched isoparaffins. In addition, these molecules in the monomethyl-branched, hydrocracked HFTL are often terminally branched, and as a result, depending on the ultimate properties of the fuel, the resulting fuel mixture About 20 to about 75% of the branched paraffins are monomethyl branches. Furthermore, among the monomethyl-branched paraffins, terminal monomethyl species predominate.

  In another aspect of the present invention, there is provided a hydrocarbon mixture produced by an integrated Fischer-Tropsch process.

  Yet another aspect of the present invention is a synthetic transportable, sulfur-free, substantially FT oxygen-free compound, having a cetane number of at least 50 and having a cloud point or freezing point of less than about 5 ° C. Fuel or blend stock for it. The synthetic transportation fuel contains about 1% to about 20% by weight of olefins, at least about 1% by weight of which is a monoolefin having a boiling range of 200 ° F. (93 ° C.) to 700 ° F. (371 ° C.). It is.

(Example 1)
And light kerosene C _{10 to 13,} to produce a _{C 13 to 20 +} drilling fluid feedstock stream, test equipment consisting of two distillation columns were used. Liquid Fischer-Tropsch oil was fed into the distillation column at about 3400 g / hr. Fischer-Tropsch oil has approximately the following composition:

Fischer - Tropsch oil is fed to the first distillation column, C ₁₃ and lighter material than was distilled overhead. The distillation column conditions were: 10 psig (69 kPa) pressure, 480 ° F. (249 ° C.) feed preheat temperature, 407 ° F. (208 ° C.) top temperature, 582 ° F. (306 ° C.) bottom temperature. there were. The first distillation column had approximately 98 inches (250 cm) of Sulzer Merapack 750Y packing. The top component of the first distillation column was operated at a pressure of 12 psig (83 kPa), a top temperature of 370 ° F. (188 ° C.), and a bottom temperature of 437 ° F. (225 ° C.). Sent to The second distillation column was packed with 28 inches (71 cm) of Sulzer EX packing. The bottom component of the second distillation column consisted of a _C10-13 light kerosene stream product. The bottom components of the first distillation column _{consisted of C13-20 +} heavy diesel and drilling fluid feedstock. The composition of C _{10 to 13} light kerosene stream (feed A) and _{C 13 to 20 +} (feed B) are shown in Tables 1 and 2.

(Example 2)
30 cc / hr of Feed A from Example 1 was sent through a syringe pump and mixed with 20 cc / min of nitrogen. This gas / liquid mixture was introduced in an upward flow to a tube packed with stainless steel mesh saddles, where the liquid was vaporized and heated to a reaction temperature of 560 ° F (293 ° C). The vaporized feed was sent in an upward stream to a reactor packed with 1/8 Alcoa S-400 alumina catalyst and dispersed in a heated sand bath. The sand bath was maintained at the reaction temperature and lifted by air. The LHCV of the reactor was maintained at about 0.26 hr ^-1 . The effluent from the reactor was concentrated and the product A and by-product water were collected in a product reservoir. The system pressure was maintained by controlling the reservoir overhead component pressure to be 50 psig (350 kPa). The aqueous layer was removed and the product of the organic layer was analyzed on a HP5890 Series II GC using a 60 m RTX1 capillary column with a 0.32 mm diameter and a 3-micron film thickness. The composition of Feed A and Product A are reported in Table 3. The product was also analyzed on a ¹ H NMR 300 MHz JEOL analyzer to confirm complete absence of alcohol.

(Example 3)
Feed A (15 cc / hr) from Example 1 was processed in the bench scale process described in Example 2. The feed was vaporized and heated to 650 ° F (343 ° C). LHCV reactor, about 0.26Hr ^-1 to make the product A, which is approximately 0.13Hr ^-1 to make the product B. The composition of the product B made in this example is reported in Table 3. ¹ H NMR analysis confirmed that the product was free of alcohol.

(Example 4)
Feed A of Example 1 was made feed A 'by adding about 5% of hexanol, and charged at 15 cc / min in the bench scale treatment described in Example 3. The supply of nitrogen was maintained at 10 cc / min. The composition of Product C of this example is reported in Table 4. ¹ H NMR analysis confirmed that the product was free of alcohol.

(Example 5)
Feed B of Example 1 was charged to the process described in Example 4. The reaction temperature was maintained at 675 ° F. (357 ° C.) and the outlet pressure was maintained at about 5 psig (35 kPa). The composition of the product D of this example is shown in Table 4.

(Example 6)
Products A and D from Example 3 and Example 5, respectively, were mixed in a ratio of about 1: 2.5. The mixed product is about 7% of the total volume of the mixed product collected overhead as the light end fraction and about 7% of the total volume of the mixed product left as it is as the heavy end fraction. Flash distilled to remove 15%. The remaining middle distillate, about 78% of the total volume of the mixed product, contained about 8% olefin. This middle distillate was then mixed 1: 1 with a well-hydrogenated Fischer-Tropsch diesel fuel (Fuel Y) without any unsaturation or significant heteroatom content. The resulting fuel sample (Fuel X) had a flash point of 146 ° F (63.3 ° C) and a cloud point of -6 ° C. Fuel X has two comparative samples: Fuel Y having a flash point of 136 ° F (57.8 ° C) and a cloud point of -21 ° C, and a flash point of 130 ° F (54.4 ° C). Blind HFRR (ASTM D-6079) lubricity test with a mineral oil based ULSD diesel fuel (Fuel Z) provided by ASTM with a cloud point of -11 ° C. The results of the lubricity test are summarized in Table 6.

  The results of the HFRR test are reported as the average wear scar diameter. A lower number indicates a smaller wear scar, and consequently a more lubricious fuel.

(Example 7)
Fuel X 'is produced by mixing Fuel X (from Example 6) with a mixture of Fuel Y and 1-dodecene in a ratio of 2.2 parts of the mixture of Fuel Y and 1-dodecene to 1 part of Fuel X. Was done. The mixing ratio of Fuel Y and 1-dodecene was determined such that Fuel X 'contained about 4% olefin. Fuel X ', Fuel Y, and Fuel Z underwent an oxidation stability test according to ASTM D-2274.

(Example 8)
Fischer-Tropsch oil and Fischer-Tropsch wax were placed in a series of test hydrotreaters and hydrocrackers. The hydrotreater was operated at 500 ° F. (260 ° C.) and the hydrocracker at 716 ° F. (380 ° C.) with a total LHSV of about 1 hr ⁻¹ . The gas / liquid ratio was 3568 scf / bbl. The resulting diesel fuel E had the following properties:

  Fuel E was analyzed by capillary GC to identify the type of branch in the sample. The results are summarized in Table 9 by volume.

  The rest of the sample was linear paraffin. In fuel E, the ratio of 2/3 methyl-branched isoparaffin or terminally branched isoparaffin to internal-branched isoparaffin (4-Me +) was about 1: 1.25. Further, the ratio of monomethyl to multimethyl in Fuel E was about 1.3: 1 (57% of the branches were monomethyl and 43% were multimethyl).

  As can be seen from the above discussion, the manufacturing methods and synthetic fuels of the present invention provide one or more of the following various advantages and benefits.

  By eliminating the hydroprocessing unit, lower capital costs are achieved. At a minimum, lower costs are achieved by reduction during hydroprocessing and milder hydroprocessing conditions.

  One advantage of the Fischer-Tropsch process of the present invention is the improved yield of useful products. The oxygenates in the hydrocrack feed reduce the life of the hydrocracking catalyst and consequently achieve the required low temperature properties of a specific boiling range and maintain conversion per pass. It is well known to those skilled in the art that higher hydrocracking temperatures are required. Higher hydrocracking temperatures result in lower product yields. Furthermore, bypassing the Fischer-Tropsch product in the middle distillate region and mixing directly with the product will result in the incorporation of alcohol into the final product. It is known that alcohol has poor low-temperature characteristics such as a freezing point and a cloud point. Poor low temperature properties are particularly detrimental in the formation of military and jet fuels. Hydrocracking conditions need to be increased to compensate for the effects of alcohol, resulting in loss of yield. Similarly, if the diverted product is hydrotreated, the paraffins produced by the hydrotreating have a high freezing point, which also results in poor low temperature properties of the mixed product. It has been known. The Fischer-Tropsch process of the present invention involves the disposal of alcohol by converting the alcohol to an olefin that is beneficial for low temperature properties.

  In the production of mineral oil and petroleum-based transportation fuels, great efforts have been made to hydrogenate existing olefins in order to improve fuel stability. Hydrogenation of this olefin is necessary. Because, in the production of mineral oil-based transportation fuels, some thermal and catalytic refining and cracking processes, which are not selective reactions, produce unsaturated compounds, and in addition to monoolefins, dienes, trienes, and alkynes This is because they are generated. It is known that these species readily oligomerize or polymerize in storage or fuel tanks, resulting in the production of rubbery substances that are harmful to fuel systems. Due to the selectivity of the Fischer-Tropsch process of the present invention, the transport fuels of the present invention have a substantially high degree of unsaturation, except for internal olefins and alpha-monoolefins that do not readily oligomerize and form rubbery materials. Contains no compounds. Further, removal of oxygenates from transport fuels as provided by the process of the present invention ensures that the fuel is not made hygroscopic. Water containing water is not a desirable property because it causes freezing of water retained in the fuel line at temperatures below 32 ° F (0 ° C).

  It is known in the art that linear and internal olefins have higher lubricity and higher metal adhesion as compared to paraffin and isoparaffin. This is explained by the high electron density of the double bonds being attracted to positive sites on the partially oxidized metal surface. Thus, fuels having a sufficiently high content of both alpha olefins and internal olefins are somewhat better lubricated than the same fuel, which is entirely paraffinic.

  Compounds containing heteroatoms such as sulfur and oxygen are known to be beneficial for lubricity and stability, and in fact have been used as additives for these purposes. However, the use of heteroatoms creates disadvantages as described above. The present invention provides a hydrocarbon fuel that does not contain a hetero atom but has lubricity and stability of the fuel containing a hetero atom.

  A notable feature of Fischer-Tropsch derived fuels is their high cetane number due to the very high content of linear paraffins and the slight branching paraffins. It is well known in the art that linear alpha olefins and internal olefins also have very high cetane numbers. Usually, the cetane number of alpha olefins and internal olefins is only 5 to 10 lower than that of the corresponding linear paraffins, and is about the same as the monobranched isomer of the same carbon number.

FIG. 1 is a schematic diagram of one embodiment of the integrated Fischer-Tropsch method of the present invention. FIG. 2 is a schematic diagram of another embodiment of the Fischer-Tropsch method of the present invention. FIG. 3 is a schematic diagram of the procedure of a hydrogenation process that can be performed in the Fischer-Tropsch method of the present invention.

Claims (36)

A hydrocarbon mixture containing olefins / paraffins mixture having a carbon number of about C _{8 ~} about C _20+, wherein the olefin / paraffin mixture,
Substantially free of oxygenates,
From about 1% to 20% by weight of the olefin, wherein at least about 1% by weight of the olefin is a monoolefin;
At least about 5% by weight of n-paraffin;
A hydrocarbon mixture comprising at least about 30% of all branching groups monomethyl and about 2-94% by weight of branched paraffins, wherein the ratio of terminal monomethyl branches to internal monomethyl branches is at least about 1: 1.5. . 2. The hydrocarbon mixture of claim 1, wherein the ratio of terminal monomethyl branches to internal monomethyl branches is at least 1: 1. The hydrocarbon mixture of claim 1, wherein the n-paraffins are present at least about 10% by weight and the ratio of terminal monomethyl branches to internal monomethyl branches is at least about 1.5: 1. The hydrocarbon mixture of claim 1, wherein the n-paraffins are present at least about 10% by weight and the ratio of terminal monomethyl branches to internal monomethyl branches is at least about 2: 1. The hydrocarbon mixture according to claim 1, wherein the olefin / paraffin mixture is a product of a Fischer-Tropsch reaction. The Fischer - feed synthesis gas Tropsch reactions, containing from 10 to 65% of _{N 2,} synthetic fuel of claim 5. A method for producing a synthetic fuel, comprising the following steps:
(A) producing light Fischer-Tropsch liquid;
(B) dehydrating all or part of the FT oxygenates in the LFTL while maintaining the olefin content in the LFTL;
(C) recovering the organic layer from the product of step (b);
(D) mixing the organic layer in the fuel for transportation. The method according to claim 7, further comprising a step (a ₁ ) of vaporizing the LFTL before step (b) and after step (a). 9. The method of claim 8, wherein the dehydration product from step (b) is in a gaseous state, and step (c) further comprises concentrating the dehydration product. Heat from condensation of the dehydrated product is recycled to at least partially vaporized in the LFTL in step (a _1), The method of claim 9. The light Fischer - Tropsch liquid, made from a feed synthesis gas containing 10 to 65% of N _2, The method of claim 7. The method according to claim 11, wherein the feed syngas is produced by a self-exothermic reforming reaction in the presence of air. A hydrocarbon mixture containing paraffin mixture having a carbon number of about C _{8 ~} about C ₂₀₊ range, the paraffin mixture,
Substantially free of oxygenates,
At least about 5% by weight of n-paraffin;
A hydrocarbon mixture comprising at least about 20% of all branching groups monomethyl and about 2-95% by weight of branched paraffins, wherein the ratio of terminal monomethyl branches to internal monomethyl branches is at least about 1: 1.5. . 14. The synthetic fuel of claim 13, wherein the ratio of terminal monomethyl branches to internal monomethyl branches is at least about 1: 1. 14. The synthetic fuel of claim 13, wherein the n-paraffins are present at least about 10% by weight and the ratio of terminal monomethyl branches to internal monomethyl branches is at least about 1.5: 1. 14. The synthetic fuel of claim 13, wherein the n-paraffins are present at least about 10% by weight and the ratio of terminal monomethyl branches to internal monomethyl branches is at least about 2: 1. 14. The synthetic fuel according to claim 13, wherein the base liquid is a product of a Fischer-Tropsch reaction. The Fischer - feed synthesis gas Tropsch reactions, containing from 10 to 65% of _{N 2,} synthetic fuel of claim 17. A method for producing a synthetic fuel, comprising the following steps:
(A) producing a light Fischer-Tropsch solution;
(B) light Fischer - distilling Tropsch _liquid, to obtain a _C 8 _{-C 20+} product with a C _{8 -C 20+} hydrocarbons and FT oxygenates;
_(C) while maintaining the olefin content of the C _{8 -C 20+ product,} dehydrating all or part of the C _{8 -C 20+} FT oxygenates in the product;
(D) recovering the dehydrated product;
(E) separating the aqueous and organic layers of the dehydration product;
(F) mixing the organic layer of the dehydration product with the transportation fuel. The C ₁₀ -C ₂₀ product obtained in step (b), dehydrating it in step (c), The method of claim 19. After the previous step (c) in step _(b), further comprising the step _{(b 1)} to vaporize the C _{8 -C 20+} product The method of claim 19. 20. The method of claim 19, wherein the dehydrated product from step (c) is in a gaseous state, and step (d) further comprises concentrating the dehydrated product. Heat from condensation of the dehydrated product is recycled to at least partially vaporize the C ₈ -C ₂₀₊ product in step (b _1), The method of claim 23. The light Fischer - Tropsch liquid is produced from a feed synthesis gas containing 10 to 65% of N _2, The method of claim 19. 25. The method of claim 24, wherein the feed syngas is produced by a self exothermic reforming reaction in the presence of air. A synthetic transport fuel comprising a middle fraction of a crude Fischer-Tropsch synthesis product, substantially free of FT oxygenates, that has not undergone a hydrogenation process. 27. The synthetic transportation fuel of claim 26, having a cloud point of 5 ° C or less. 28. The synthetic transportation fuel of claim 27, comprising less than 1% by weight of an aromatic compound. 28. The synthetic transportation fuel of claim 27, comprising 1 ppm or less of nitrogen. A transportation fuel produced by the method of claim 7. 20. A transportation fuel produced by the method of claim 19. A blend stock for transportation fuel produced by the method of claim 7. 20. A blend stock for transportation fuel produced by the method of claim 19. A synthetic transport fuel comprising essentially olefins and paraffins without heteroatoms or additives, wherein the lubricity measured according to ASTM D-6079 is 0.45 mm or less at 60 ° C. . A paraffin and olefin derived from the product of the Fischer-Tropsch synthesis, containing no heteroatoms or additives, and having a total amount of insoluble matter measured according to ASTM D-2274 of 1.5 mg / 100 ml or less, for synthetic transportation. fuel. It contains paraffins and olefins from the product of the Fischer-Tropsch synthesis, contains no heteroatoms, has a lubricity of less than or equal to 0.45 mm at 60 ° C. measured according to ASTM D-6079, and is measured according to ASTM D-2274. A synthetic transport fuel, wherein the stability of the total amount of the insolubles is 1.5 mg / 100 ml or less.

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