AU2007322907A1

AU2007322907A1 - Process for producing liquid fuel

Info

Publication number: AU2007322907A1
Application number: AU2007322907A
Authority: AU
Inventors: Hiroyuki Seki
Original assignee: Nippon Oil Corp
Current assignee: Eneos Corp
Priority date: 2006-11-21
Filing date: 2007-08-30
Publication date: 2008-05-29
Anticipated expiration: 2027-08-30
Also published as: JP2013079402A; AU2007322907B2; MY149444A; RU2437716C2; CN101547996A; RU2009123492A; WO2008062595A1; JP5408879B2; JPWO2008062595A1

Description

FP07-0387-00 DESCRIPTION PROCESS FOR PRODUCING LIQUID FUEL Technical Field [0001] The present invention relates to a production method of liquid 5 fuel from paraffinic hydrocarbons in the presence of hydrogen. Background Art [0002] The demand for clean liquid fuels with low sulfur and aromatic hydrocarbon contents has been rapidly rising in recent years. In response, several clean fuel production methods have already been 10 investigated in the field of fuel oil production. Expectations are especially high for methods involving hydrocracking of paraffinic hydrocarbons such as waxes in the presence of catalysts. [0003] In hydrocracking processes for paraffinic hydrocarbons, it is important for the catalyst to have high activity and to obtain high yield 15 of the useful middle distillate, for increased economy of the process. The pour point of the obtained gas oil fraction must also be low. In other words, improvement of the economy of the process may depend on development of a high performance hydrocracking catalyst which can achieve high cracking activity, high yield of the middle distillate 20 and low pour point of the product gas oil. [0004] Hydrocracking using vacuum gas oil as the feedstock is already commercially available, and techniques have been established with a history of several decades. However, because the reactivity of paraffinic hydrocarbons abundant in normal paraffins such as waxes, in 25 particular, differs substantially from that of vacuum gas oils such that catalysts for vacuum gas oil cannot easily be diverted for use, it is

I

FP07-0387-00 currently an object of avid research to develop a high performance catalyst for paraffinic hydrocarbons. Some patents have been granted, although few in number. For example, Patent document 1 discloses a catalyst having platinum supported on a support containing silica 5 alumina. Also, Patent document 2 discloses research involving hydrocracking of paraffmic hydrocarbons using a catalyst comprising platinum supported on a support containing a combination of crystalline aluminosilicate (zeolite) and the amorphous solid acid silica-alumina. 10 [Patent document 1] Japanese Unexamined Patent Publication HEI No. 6-41549 [Patent document 2] International Patent Publication No. 2004/028688 Disclosure of the invention [Problems to Solved by the Invention] 15 [0005] The following three conditions are important for increasing the economy of the hydrocracking process for paraffinic hydrocarbons: (1) high cracking activity of the catalyst; (2) high yield of middle distillate; and (3) satisfactory cold flow property for the produced middle distillate 20 (especially the gas oil fraction). However, high cracking activity of the catalyst tends to lead to decomposition of the produced middle distillate, resulting in a low yield of middle distillate. In other words, (1) and (2) are conflicting, and it is considered very difficult to achieve both in conventional hydrocracking processes. This trade-off is a 25 major impediment against improving the economy of hydrocracking processes for paraffinic hydrocarbons. 2 FP07-0387-00 [0006] The present invention has been accomplished in light of these circumstances, and its object is to provide a production method of liquid fuel that allows high levels of both cracking activity of the catalyst and the yield of the middle distillate to be achieved in a 5 hydrocracking process for paraffmic hydrocarbons, whereby a middle distillate with a satisfactory cold flow property can be obtained. [Means for Solving the Problems] [0007] In order to solve the problems described above, the invention provides a production method of liquid fuel by hydrocracking of 10 paraffinic hydrocarbons, the method comprising the step of contacting paraffinic hydrocarbons with a catalyst in the presence of hydrogen, the catalyst comprising a support containing a crystalline aluminosilicate and an amorphous solid acid, and at least one metal selected from among metals of Group VIII of the Periodic Table supported on the 15 support, and the catalyst further containing at least one element selected from phosphorus and boron. [0008] By thus using as the hydrocracking catalyst a catalyst comprising a support containing a crystalline aluminosilicate and an amorphous solid acid, and at least one metal selected from metals of 20 Group VIII of the Periodic Table supported on the support, and further containing at least one element selected from phosphorus and boron, it is possible to achieve high levels of both cracking activity of the catalyst and the yield of the middle distillate, while also obtaining a middle distillate with a satisfactory cold flow property. 25 [0009] The term " middle distillate " is used according to the invention to mean the petroleum or synthesis fraction with a boiling 3 FP07-0387-00 point range of 145-360'C, in the product of the hydrocracking. A typical example of a middle distillate is the middle distillate produced by Fischer-Tropsch (FT) synthesis. A gas oil fraction is a fraction of the middle distillate having a boiling point of 260-360'C. 5 [0010] According to the invention, it is preferred for at least 70 % by mass of the paraffinic hydrocarbons to be normal paraffins. The normal paraffin content is determined by gas chromatography. [0011] Also according to the invention, the crystalline aluminosilicate is preferably ultrastable Y-zeolite. 10 [0012] When the catalyst contains phosphorus, the phosphorus content is preferably 0.2-5.0 % by mass as elemental phosphorus based on the total catalyst weight. [0013] When the catalyst contains boron, the boron content is preferably 0.5-4.0 % by mass as elemental boron based on the total 15 catalyst weight. [0014] The metal supported on the support in the catalyst is preferably at least one selected from palladium and platinum. [Effect of the Invention] [0015] As mentioned above, the production method of liquid fuel 20 according to the invention allows high levels of both cracking activity of the catalyst and the yield of the middle distillate to be achieved, while obtaining a middle distillate with a satisfactory cold flow property. Brief Description of the Drawings 25 [0016] Fig. 1 is an illustration showing an example of a fixed bed reactor used for the invention. 4 FP07-0387-00 [Explanation of Symbols] [0017] 1: Reaction column, 2: hydrocracking catalyst layer, 3: distilling apparatus. Best Mode for Carrying Out the Invention 5 [0018] Preferred embodiments of the invention will now be described in detail. [0019] Fig. 1 is an illustration showing an example of a fixed bed reactor suitable for use according to the invention. In the fixed bed reactor shown in Fig. 1, a hydrocracking catalyst layer 2 is provided in 10 a reaction column 1. At the top of the reaction column 1 there is connected a line Li for supply of hydrogen into the reaction column 1, while a line L2 for supply of the paraffinic hydrocarbon as the feedstock is connected upstream from the connection of the line Li with the reaction column 1. Separately, at the bottom of the reaction 15 column 1 there is connected a line L3 for removal of the cracking product from the reaction column 1 after hydrocracking, with the other end of the line L3 being connected to an atmospheric pressure distilling apparatus 3. [0020] The paraffinic hydrocarbon feedstock preferably consists of 20 hydrocarbons with a normal paraffin molecule content of at least 70 % by mass. The carbon number distribution among the paraffinic hydrocarbons is not particularly restricted, and there may be used C18 or greater hydrocarbons that are solid at ordinary temperature, and specifically paraffinic hydrocarbons, commonly known as waxes. 25 [0021] The method for producing the paraffinic hydrocarbon feedstock is not particularly restricted, and the invention may be 5 FP07-0387-00 applied to various petroleum and synthetic paraffinic hydrocarbons, but a particularly preferred paraffinic hydrocarbon is FT wax produced by Fischer-Tropsch synthesis. [0022] The hydrocracking catalyst layer 2 is composed of a catalyst 5 comprising a support containing a crystalline aluminosilicate and an amorphous solid acid, and at least one metal selected from metals of Group VIII of the Periodic Table supported on the support, and further containing at least one element selected from phosphorus and boron. [0023] The term "aluminosilicate" is used according to the invention 10 to mean a metal oxide consisting of the three elements aluminum, silicon and oxygen, although it may also contain other metal elements within a range that does not impede the effect of the invention. Examples of metal elements that may be included therewith include titanium, lanthanum, manganese, gallium and zinc, among which 15 titanium and lanthanum are preferred. The amount of other metal elements is preferably no greater than 5 % by mass and more preferably no greater than 3 % by mass with respect to the total amount of aluminum and silicon in terms of their oxides (the total amount of alumina and silica). 20 [0024] The crystallinity of the aluminosilicate can be estimated by the proportion of tetracoordinated aluminum atoms among the total aluminum atoms, and the proportion can be measured by 27 Al solid NMR. The term "crystalline aluminosilicate" is used according to the invention to mean an aluminosilicate of which at least 70% of the 25 aluminum is tetracoordinated aluminum. There are no particular restrictions on the crystalline aluminosilicate used so long as the 6 FP07-0387-00 proportion of tetracoordinated aluminum is at least 70%, but the proportion of tetracoordinated aluminum is preferably at least 80% and more preferably at least 85%. [0025] Zeolite may be used as a crystalline aluminosilicate. As 5 preferred crystalline aluminosilicates there may be mentioned Y zeolite, ultrastable Y-zeolite (USY-zeolite), beta zeolite and mordenite, among which USY-zeolite is particularly preferred. A crystalline aluminosilicate may be used alone, or two or more thereof may be used in combination. 10 [0026] The mean particle size of the crystalline aluminosilicate is not particularly restricted, but it is preferably no greater than 1.0 pm and more preferably no greater than 0.5 pm. A crystalline aluminosilicate with a particle size of 1.0 pm or smaller will tend to further improve the yield of the middle distillate. 15 [0027] The crystalline aluminosilicate content in the catalyst is also not particularly restricted, but it is preferably 0.1-8.0 % by mass based on the total weight of the catalyst. [0028] As amorphous solid acids there may be mentioned silica alumina, silica-zirconia, silica-titania, silica-magnesia, alumina 20 zirconia and alumina-boria, among which alumina-boria is preferred. [0029] The amorphous solid acid content of the catalyst is not particularly restricted but is preferably 5-70 % by mass with respect to the total weight of the catalyst. [0030] The support comprising the crystalline aluminosilicate and 25 amorphous solid acid may be shaped without using a binder, but normally a binder will be used. The binder used in such cases is not 7 FP07-0387-00 particularly restricted, but alumina and silica may be used, with alumina being most preferred. There are no particular restrictions on the amount of binder used, but it is preferably 20-90 % by mass and more preferably 40-80 % by mass based on the total weight of the 5 support. By using the binder in a range of 20-90 % by mass it is possible to efficiently obtain a catalyst with sufficient strength. [0031] The catalyst of the hydrocracking catalyst layer 2 also contains at least one element selected from phosphorus and boron. [0032] When the catalyst contains phosphorus, the phosphorus 10 content is preferably 0.1-8.0 % by mass and more preferably 0.2-5.0 % by mass as elemental phosphorus based on the total catalyst weight. If the phosphorus content is less than 0.1 % by mass, the improving effect on the cracking activity will tend to be inadequate. If the phosphorus content exceeds 8.0 % by mass there will generally be no 15 improving effect on the cracking activity commensurate with the increased content. The phosphorus content in the catalyst can be measured by means such as inductively coupled plasma atomic emission spectroscopic analysis. [0033] When the catalyst contains boron, the boron content is 20 preferably 0.3-8.0 % by mass and more preferably 0.5-4.0 % by mass as elemental boron based on the total catalyst weight. A boron content of less than 0.3 % by mass will tend to result in an insufficient improving effect on the cracking activity. If the boron content exceeds 8.0 % by mass there will generally be no improving effect on 25 the cracking activity commensurate with the increased content, and the catalyst strength will tend to be lower. The boron content in the 8 FP07-0387-00 catalyst can also be measured by means such as inductively coupled plasma atomic emission spectroscopic analysis. [0034] The method of introducing phosphorus into the catalyst may be, for example, a method wherein a phosphorus-containing compound 5 such as phosphoric acid or phosphorus pentaoxide is added to the uncalcined binder (in the boehmite state if the binder is alumina, same hereunder). The method of introducing boron into the catalyst may be, for example, a method wherein a boron-containing compound such as boric acid is added to the uncalcined binder. It is not necessary to 10 employ the method of introducing phosphorus or boron described above when the crystalline aluminosilicate or amorphous solid acid contains phosphorus or boron, such as when alumina-boria is used as the amorphous solid acid, but the method of introducing phosphorus or boron described above is useful for adjusting the phosphorus or boron 15 content in the catalyst. [0035] At least one metal selected from metals of Group VIII of the Periodic Table as the active component is supported on the support described above (or the molded article when molding is carried out using the binder). As metals of Group VIII there may be mentioned, 20 specifically, cobalt, nickel, rhodium, palladium, iridium and platinum, among which palladium and platinum are preferred. Using a metal other than one of Group VIII of the Periodic Table as the active component of the catalyst will notably reduce the yield of the middle distillate. 25 [0036] A metal of Group VIII may be loaded alone, or a combination of two or more may be used. For example, both platinum and 9 FP07-0387-00 palladium may be loaded together. The loading amount of the metal of Group VIII is not particularly restricted but is preferably 0.02-2 % by mass based on the total weight of the catalyst. The method of loading the metal of Group VIII onto the support (or the molded article 5 when molding is carried out using the binder) may be loading by ordinary impregnation or ion exchange in the support or molded article. [0037] The hydrocracking catalyst layer 2 composed of the catalyst is preferably treated for reduction of the metal in a reducing gas atmosphere such as hydrogen before the hydrocracking. The reducing 10 conditions are not particularly restricted, but preferably the reducing temperature is 300-360*C and the reducing time is 1-6 hours. [0038] As regards the reaction conditions for hydrocracking in the reaction column 1, the temperature may be 200-450*C, the hydrogen pressure 0.5-12 MPa and the liquid space velocity of the paraffinic 15 hydrocarbon feedstock 0.1-10 h-1, while preferably the temperature is 250-380 0 C, the hydrogen pressure is 2.0-8.0 MPa and the liquid space velocity of the paraffinic hydrocarbon feedstock is 0.3-5.0 h-1. [0039] The distilling apparatus 3 can distill the cracking product of hydrocracking, depending on the distillation properties. For example, 20 the cracking product may contain, in addition to the middle distillates with a boiling point of 145-360'C, also light distillates (naphtha fraction, etc.) with a boiling point of below 145'C and wax fractions with a boiling point of above 360*C, which can be separated by the distilling apparatus 3. Also, the middle distillates may contain 25 kerosene fractions (fractions with a boiling point of 145-260'C) in addition to the gas oil fractions, and these may also be separated by the 10 FP07-0387-00 distilling apparatus 3. Each separated fraction is transported to subsequent processes by lines (L4-L7) connected to the distilling apparatus 3. [0040] According to the embodiment described above, the catalyst 5 used in the hydrocracking catalyst layer 2 is a catalyst comprising a support containing a crystalline aluminosilicate and an amorphous solid acid, and at least one metal selected from metals of Group VIII of the Periodic Table supported on the support, and also containing at least one element selected from phosphorus and boron, so that a high level 10 of both cracking activity of the catalyst and the yield of the middle distillate can be achieved while obtaining a middle distillate with a satisfactory cold flow property. [0041] The invention is not limited to this embodiment, however. For example, although the hydrocracking catalyst layer 2 has a single 15 layer structure according to this embodiment, different hydrocracking catalyst layers may be laminated to form a multilayer structure instead. When unreacted paraffimic hydrocarbons are present in the cracking product, a transport line connecting the distilling apparatus 3 and the top of the reaction column 1 may be provided and the unreacted wax 20 fraction separated at the distilling apparatus 3 introduced into the reaction column 1 through the transport line and resupplied for hydrocracking (bottom recycling). Also, while the apparatus described above for hydrocracking of paraffinic hydrocarbons was a fixed bed reactor, there is no particular restriction so long as it allows 25 contact between the wax as feedstock and hydrocracking catalyst, and for example, it may be a fluidized bed reactor instead. 11 FP07-0387-00 [Examples] [0042] The present invention will now be explained in greater detail based on examples and comparative examples, with the understanding that these examples are in no way limitative on the invention. 5 [0043] (Preparation of catalyst A) After combining 30 g of USY zeolite with a mean particle size of 0.5 pm (silica/alumina (molar) ratio: 37), 500 g of silica-alumina (alumina content: 14 % by mass) and 400 g of phosphorus-containing boehmite (using phosphoric acid for adjustment to a phosphorus content of 5.0 % 10 by mass in the boehmite), the mixture was used to prepare a cylindrical molded article with a diameter of 1/16 inch (approximately 1.6 mm). The molded article was calcined in air at 500'C for 1 hour to obtain a support. [0044] The obtained support was impregnated with a 15 dichlorotetraammine platinum (II) aqueous solution and dried at 120'C for 3 hours, after which it was calcined at 500'C for 1 hour to obtain catalyst A (phosphorus content: 1.8 % by mass, platinum loading amount: 0.5 % by mass). [0045] (Preparation of catalyst B) 20 After combining 30 g of USY zeolite with a mean particle size of 0.5 pm (silica/alumina (molar) ratio: 37), 500 g of silica-alumina (alumina content: 14 % by mass) and 400 g of boron-containing boehmite (using boric acid for adjustment to a boron content of 10.0 % by mass in the boehmite), the mixture was used to prepare a cylindrical molded article 25 with a diameter of 1/16 inch (approximately 1.6 mm). The molded article was calcined in air at 500'C for 1 hour to obtain a support. 12 FP07-0387-00 [0046] The obtained support was impregnated with a dichlorotetraammine platinum (II) aqueous solution and dried at 120 0 C for 3 hours, after which it was calcined at 500 0 C for 1 hour to obtain catalyst B (boron content: 3.7 % by mass, platinum loading amount: 5 0.5 % by mass). [0047] (Preparation of catalyst C) After combining 30 g of USY zeolite with a mean particle size of 0.5 gm (silica/alumina (molar) ratio: 37), 500 g of silica-alumina (alumina content: 14 % by mass) and 400 g of phosphorus- and boron-containing 10 boehmite (using phosphoric acid for adjustment to a phosphorus content of 4.0 % by mass and boric acid for adjustment to a boron content of 6.0 % by mass in the boehmite), the mixture was used to prepare a cylindrical molded article with a diameter of 1/16 inch (approximately 1.6 mm). The molded article was calcined in air at 15 500'C for 1 hour to obtain a support. [0048] The obtained support was impregnated with a dichlorotetraammine platinum (II) aqueous solution and dried at 120'C for 3 hours, after which it was calcined at 500'C for 1 hour to obtain catalyst C (phosphorus content: 1.2 % by mass, boron content: 2.1 % 20 by mass, platinum loading amount: 0.5 % by mass). [0049] (Preparation of catalyst D) After combining 30 g of USY zeolite with a mean particle size of 0.8 pm (silica/alumina (molar) ratio: 32), 500 g of silica-zirconia (zirconia content: 30 % by mass) and 400 g of phosphorus-containing boehmite 25 (using phosphoric acid for adjustment to a phosphorus content of 5.0 % by mass in the boehmite), the mixture was used to prepare a cylindrical 13 FP07-0387-00 molded article with a diameter of 1/16 inch (approximately 1.6 mm). The molded article was calcined in air at 500'C for 1 hour to obtain a support. [0050] The obtained support was impregnated with a 5 dichlorotetraammine platinum (II) aqueous solution and dried at 120 0 C for 3 hours, after which it was calcined at 500'C for 1 hour to obtain catalyst D (phosphorus content: 1.8 % by mass, platinum loading amount: 0.5 % by mass). [0051] (Preparation of catalyst E) 10 A catalyst was prepared in the same manner as catalyst A except for using boehmite containing no phosphorus, in order to obtain catalyst E (platinum loading amount: 0.5 % by mass). [0052] (Preparation of catalyst F) A catalyst was prepared in the same manner as catalyst D except for 15 using boehmite containing no phosphorus, in order to obtain catalyst F (platinum loading amount: 0.5 % by mass). [0053] (Example 1) Catalyst A (100 ml) was packed into a fixed bed circulating reactor for hydrocracking of paraffinic hydrocarbon. For this example, FT wax 20 with a normal paraffin content of 96 % by mass and a carbon number distribution of 20-80 was used as the feedstock, while the hydrogen pressure was 4 MPa and the liquid space velocity of the feedstock was 2.0 h-1. The reaction temperature yielding cracking product (fraction with boiling point of 360'C and below, same hereunder) at 80 % by 25 mass with respect to the feedstock was determined, and the yield of the middle distillate (fraction with a boiling point of 145-360'C) with 14 FP07-0387-00 respect to the feedstock and the pour point of the gas oil product (fraction with a boiling point of 260-360'C) at that reaction temperature were measured. The results are shown in Table 1. [0054] (Example 2) 5 Hydrocracking of paraffinic hydrocarbon was carried out in the same manner as Example 1 except for using catalyst B instead of catalyst A, and the reaction temperature yielding cracking product at 80 % by mass with respect to the feedstock, as well as the yield of the middle distillate with respect to the feedstock and the pour point of the gas oil 10 product at that reaction temperature, were determined. The results are shown in Table 1. [0055] (Example 3) Hydrocracking of paraffinic hydrocarbon was carried out in the same manner as Example 1 except for using catalyst C instead of catalyst A, 15 and the reaction temperature yielding cracking product at 80 % by mass with respect to the feedstock, as well as the yield of the middle distillate with respect to the feedstock and the pour point of the gas oil product at that reaction temperature, were determined. The results are shown in Table 1. 20 [0056] (Example 4) Hydrocracking of paraffinic hydrocarbon was carried out in the same manner as Example 1 except for using catalyst D instead of catalyst A, and the reaction temperature yielding cracking product at 80 % by mass with respect to the feedstock, as well as the yield of the middle 25 distillate with respect to the feedstock and the pour point of the gas oil product at that reaction temperature, were determined. The results are 15 FP07-0387-00 shown in Table 1. [0057] (Comparative Example 1) Hydrocracking of paraffinic hydrocarbon was carried out in the same manner as Example 1 except for using catalyst E instead of catalyst A, 5 and the reaction temperature yielding cracking product at 80 % by mass with respect to the feedstock, as well as the yield of the middle distillate with respect to the feedstock and the pour point of the gas oil product at that reaction temperature, were determined. The results are shown in Table 1. 10 [0058] (Comparative Example 2) Hydrocracking of paraffinic hydrocarbon was carried out in the same manner as Example 1 except for using catalyst F instead of catalyst A, and the reaction temperature yielding cracking product at 80 % by mass with respect to the feedstock, as well as the yield of the middle 15 distillate with respect to the feedstock and the pour point of the gas oil product at that reaction temperature, were determined. The results are shown in Table 1. 16 FP07-0387-00 [0059] [Table 1] Cracking Yield of the Pour point of temperature middle distillate the gas oil (*C) (% by mass) product (*C) Example 1 293 57.1 -25.0 Example 2 296 56.6 -22.5 Example 3 291 57.3 -22.5 Example 4 299 56.8 -25.0 Comp. Ex. 1 300 54.8 -22.5 Comp. Ex. 2 306 54.5 -22.5 17

Claims

1. A production method of liquid fuel by hydrocracking of paraffinic hydrocarbons, the method comprising the step of contacting paraffinic hydrocarbons with a catalyst in the presence of hydrogen, 5 the catalyst comprising a support containing a crystalline aluminosilicate and an amorphous solid acid, and at least one metal selected from metals of Group VIII of the Periodic Table supported on the support, and the catalyst further comprising at least one element selected from phosphorus and boron. 10

2. A production method of liquid fuel according to claim 1, wherein the paraffinic hydrocarbons contains at least 70 % by mass normal paraffins.

3. A production method of liquid fuel according to claim 1 or 2, wherein the crystalline aluminosilicate is ultrastable Y-zeolite. 15

4. A production method of liquid fuel according to any one of claims 1 to 3, wherein the phosphorus content of the catalyst is 0.2-5.0 % by mass as elemental phosphorus based on the total weight of the catalyst.

5. A production method of liquid fuel according to any one of 20 claims 1 to 4, wherein the boron content of the catalyst is 0.5-4.0 % by mass as elemental boron based on the total weight of the catalyst.

6. A production method of liquid fuel according to any one of claims 1 to 5, wherein the metal is at least one selected from palladium and platinum. 18