Method for producing jet fuel from grease raw materials

Abstract

The invention relates to a method for producing jet fuel from a grease raw material, which comprises the following steps of: contacting the grease raw material with a hydrotreating catalyst in a hydrotreating reaction zone to react, feeding obtained liquid hydrocarbon into a first hydroisomerization reaction zone, and setting an optional second hydroisomerization reaction zone, the obtained diesel fraction is circulated back to the first hydroisomerization reaction zone or enters the second hydroisomerization reaction zone for reaction, and the jet fuel is obtained after reaction effluent is separated. The high-quality bio-jet fuel can be prepared with high yield.

Description

Technical Field

[0001] The present invention relates to a method for preparing bio - jet fuel, and specifically, a method for producing bio - jet fuel from oil - based raw materials. Background Art

[0002] With the tightening of the supply of traditional fossil energy and the increasing pressure of carbon dioxide emission reduction, how to effectively reduce carbon dioxide gas emissions while increasing fuel supply is an important issue facing the refining industry. Biodiesel fuel prepared from renewable biomass such as animal and vegetable oils or agricultural and forestry waste has significantly lower greenhouse gas emissions in its full life cycle than fossil diesel fuel. Developing biomass fuel is considered one of the effective means to solve this problem.

[0003] Biofuels have gradually attracted people's attention mainly for the following reasons: 1. Biofuels are renewable energy sources; 2. The carbon - containing characteristics of biofuels are close to those of existing fuels; 3. The carbon dioxide absorbed by the precursors of biofuels can reduce the net emissions of greenhouse gases; 4. Bioenergy is more evenly distributed than fossil energy.

[0004] The traditional method for converting vegetable oil or other fatty acid derivatives into liquid fuel is transesterification. Transesterification is an ester - exchange reaction using alcohol under the action of a catalyst, which converts the triglycerides forming vegetable oil into the corresponding fatty acid alkyl esters, usually fatty acid methyl esters. However, the low - temperature fluidity of fatty acid methyl esters limits their use in low - temperature environments. The low - temperature fluidity of fatty acid methyl esters is determined by the chain characteristics of their fatty acids. The presence of carbon - carbon double bonds can improve low - temperature fluidity but reduces the stability of fatty acid methyl esters. Since the presence of oxygen in fatty acid methyl esters will lead to higher NOx emissions compared to traditional diesel fuels.

[0005] CN103059902B discloses a method for preparing a jet fuel blending component from animal and vegetable oils, including: animal and vegetable oils enter the first hydro - reactor, and in the presence of hydrogen, contact with a hydro - treatment catalyst to carry out hydro - deoxygenation reaction; the hydrocarbon liquid - phase stream obtained after the reaction enters an intermediate fractionation tower, and the C16 - C24 fraction obtained by fractionation enters the second hydro - reactor from the top, and in the presence of hydrogen, undergoes a selective cracking reaction in the cracking section and then enters the isomerization section for isomerization reaction; the C6 - C15 fraction obtained by fractionation enters the isomerization section from the middle for isomerization reaction; the hydrocarbon liquid - phase stream obtained after the reaction in the second hydro - reactor enters a product fractionation tower, and the jet fuel blending component is obtained by fractionation.

[0006] A method for preparing jet fuel is disclosed in CN103059900B. The method includes: (1) under hydrodeoxygenation conditions, contacting vegetable oil and / or animal fat, hydrogen with a hydrodeoxygenation catalyst to obtain C8-C24 normal paraffins; (2) under hydroisomerization conditions, contacting the C8-C24 normal paraffins, hydrogen with a hydroisomerization catalyst; (3) under hydrorefining conditions, contacting the product after the contact in step (2), hydrogen with a hydrorefining catalyst and then fractionating to obtain jet fuel; wherein the hydroisomerization catalyst contains a support and a metal active component, the support contains a silicon phosphoaluminate molecular sieve, and the metal active component contains one or more of Group VIII metal elements.

[0007] In the prior art, the preparation of hydroisomerization catalysts usually involves ammonium exchange after crystallization and then extrusion molding. However, the alkali metal content in the obtained catalysts is generally below 0.1 wt%, which is difficult to further reduce, resulting in limited catalytic activity of the catalysts. Therefore, how to further improve the catalytic activity of the catalysts is also an important problem in the prior art. Summary of the Invention

[0008] The object of the present invention is to provide a method for producing jet fuel from oil-based raw materials on the basis of the prior art to solve the problem of low yield of bio-jet fuel in the prior art.

[0009] The method for producing jet fuel from oil-based raw materials provided by the present invention includes:

[0010] (1) The oil-based raw material and hydrogen enter a hydrotreating reaction zone together and react with a hydrotreating catalyst under hydrotreating reaction conditions to obtain a hydrotreating reaction effluent. The active metal component of the hydrotreating catalyst is at least one metal component selected from Group VIII and / or at least one metal component selected from Group VIB.

[0011] (2) Separating the hydrotreating reaction effluent obtained in step (1) to obtain a liquid hydrocarbon, water and a gas stream.

[0012] (3) The liquid hydrocarbon obtained in step (2) enters a first hydroisomerization reaction zone and reacts with a hydroisomerization catalyst under first hydroisomerization reaction conditions. After the obtained hydroisomerization reaction effluent is subjected to gas-liquid separation and liquid phase fractionation, a naphtha fraction, a jet fuel fraction and a diesel fraction are obtained, and at least part of the obtained diesel fraction is recycled to the inlet of the first hydroisomerization reaction zone.

[0013] (4) An optional second hydroisomerization reaction zone is provided. The diesel fraction obtained in step (3) enters the second hydroisomerization reaction zone and reacts with a hydroisomerization catalyst under the second hydroisomerization reaction conditions. The obtained hydroisomerization reaction effluent is subjected to gas-liquid separation and liquid-phase fractionation together with the hydroisomerization reaction effluent of step (3);

[0014] In steps (3) and (4), the hydroisomerization catalyst includes a carrier and an active metal component supported on the carrier. The carrier contains ZSM-48 molecular sieve. The molar ratio of silica to alumina in the ZSM-48 molecular sieve is not less than 40. The specific surface area of the ZSM-48 molecular sieve is not less than 200 m 2 / g. The crystal grains of the ZSM-48 molecular sieve are ellipsoidal, with a major axis not exceeding 700 nm and a major axis to minor axis ratio of 1-3:1;

[0015] The active metal component is Pt and / or Pd;

[0016] In the hydroisomerization catalyst, based on the total amount of the hydroisomerization catalyst, the content of the molecular sieve on a dry basis is 20-80% by weight, and based on the element, the content of the active metal component is 0.1-20% by weight;

[0017] Among them, based on the total amount of the carrier, the content of the basic metal oxide in the carrier is not higher than 0.001% by weight.

[0018] In the present invention, the oil and fat raw materials are animal and vegetable oils and / or waste cooking oil. The animal and vegetable oils include vegetable oils and animal fats, as well as raw materials containing glycerides and free fatty acids, and fatty acid methyl esters or fatty acid ethyl esters prepared by transesterification of vegetable oils and / or animal fats. The waste cooking oil is the oil waste that is not suitable for further consumption generated in the processing of animal and vegetable oils and in edible consumption. It includes fatty acids, acidified oils, etc. generated in the production of edible oil from oilseeds; various waste cooking oils such as frying waste oil, kitchen waste oil, swill oil, etc. generated from the use of edible oil in residential households, hotels, the catering industry, and food production enterprises; animal fats by-produced in the production and processing of meat, and also expired edible oils, etc.

[0019] In one embodiment of the present invention, the carrier of the hydrotreating catalyst is selected from one or more of alumina, silica, titanium oxide, and zirconium oxide. The Group VIII metal component is cobalt and / or nickel, and the Group VIB metal component is molybdenum and / or tungsten; calculated as oxides and based on the hydrotreating catalyst, the content of cobalt and / or nickel is 1-10% by weight, and the content of molybdenum and / or tungsten is 10-45% by weight.

[0020] In one embodiment of the present invention, the hydrotreating reaction conditions are as follows: reaction temperature is 250 - 450 °C, reaction pressure is 3.0 - 10.0 MPa, volume hourly space velocity is 0.1 - 10.0 h -1 , hydrogen - to - oil volume ratio is 300 - 2000 Nm 3 / m 3 ;

[0021] Preferably, the hydrotreating reaction conditions are as follows: reaction temperature is 300 - 400 °C, reaction pressure is 4.0 - 8.0 MPa, volume hourly space velocity is 0.5 - 5.0 h -1 , hydrogen - to - oil volume ratio is 500 - 1500 Nm 3 / m 3 .

[0022] In order to maintain the sulfided state of the hydrotreating catalyst, a sulfiding agent is preferably added to the oil - based raw material, and the concentration of the sulfiding agent is 0.01 - 0.5 wt%. The sulfiding agent is one or more of H2S, CS2, dimethyl disulfide, methyl sulfide, di - tert - butyl polysulfide (SZ 54 ), n - butyl sulfide, and thiophene.

[0023] The reactor in the hydrotreating reaction zone is a fixed - bed reactor. The reactor can be provided with multiple beds, and the reaction temperature rise is controlled by injecting cold hydrogen between the beds, or by the way of recycle oil, or both methods are used simultaneously.

[0024] In the hydrotreating reaction zone, the oil - based raw material mainly undergoes olefin saturation and hydrodeoxygenation reactions. Among them, the oxygen in the oil - based raw material is mainly removed in the form of water production. The hydrotreating reaction effluent mainly consists of alkanes with carbon numbers of 8 - 24, and also includes water, carbon monoxide, carbon dioxide, hydrogen sulfide, ammonia, and hydrogen, etc.

[0025] In one embodiment of the present invention, in step (2), the hydrotreating reaction effluent enters a separator for gas - liquid separation to obtain a liquid stream, water, and a gas stream. The obtained liquid stream sequentially enters a stripping column for stripping and a dehydration column for dehydration to remove dissolved hydrogen sulfide, ammonia, and water, and obtain a liquid hydrocarbon.

[0026] The gas stream can be directly recycled or can be obtained as a hydrogen - rich gas through a hydrogen purification unit, and the obtained hydrogen - rich gas is recycled. The hydrogen purification unit can use conventional pressure swing adsorption technology or membrane separation technology.

[0027] In one embodiment of the present invention, the separator is selected from any combination of two or more of a hot high - pressure separator, a hot low - pressure separator, a cold high - pressure separator, and a cold low - pressure separator.

[0028] In step (3) of the present invention, the obtained liquid hydrocarbon enters the first hydroisomerization reaction zone and reacts with a hydroisomerization catalyst under the first hydroisomerization reaction conditions to obtain a first hydroisomerization reaction effluent. After the obtained hydroisomerization reaction effluent undergoes gas-liquid separation and liquid-phase fractionation, a naphtha fraction, a jet fuel fraction, and a diesel fraction are obtained. In one embodiment of the present invention, all of the obtained diesel fraction is recycled to the inlet of the first hydroisomerization reaction zone.

[0029] In step (4) of the present invention, an optional second hydroisomerization reaction zone is provided. In one embodiment of the present invention, part or all of the diesel fraction obtained in step (3) enters the second hydroisomerization reaction zone and reacts with a hydroisomerization catalyst under the second hydroisomerization reaction conditions.

[0030] In one embodiment of the present invention, the first hydroisomerization reaction conditions and the second hydroisomerization reaction conditions in steps (3) and (4) are as follows: the reaction temperature is 200 - 500 °C, the reaction pressure is 1.0 - 15.0 MPa, the volume space velocity is 0.1 - 10.0 h -1 and the hydrogen-oil volume ratio is 200 - 1500 Nm 3 / m 3 ;

[0031] Preferably, the first hydroisomerization reaction conditions and the second hydroisomerization reaction conditions are as follows: the reaction temperature is 280 - 450 °C, the reaction pressure is 2.0 - 8.0 MPa, the volume space velocity is 0.5 - 5.0 h -1 and the hydrogen-oil volume ratio is 300 - 1000 Nm 3 / m 3 ;

[0032] Preferably, the reaction temperature of the second hydroisomerization reaction conditions is 5 - 30 °C higher than the reaction temperature of the first hydroisomerization reaction conditions.

[0033] In one embodiment of the present invention, in the hydroisomerization catalyst, based on the total amount of the hydroisomerization catalyst, the content of the molecular sieve on a dry basis is 30 - 70% by weight, and based on elements, the content of the active metal component is 0.2 - 10% by weight.

[0034] In one embodiment of the present invention, the hydroisomerization catalyst further contains a binder, and the binder is alumina and / or silica;

[0035] Based on the total amount of the hydroisomerization catalyst, the content of the binder is 20 - 80% by weight.

[0036] In one embodiment of the present invention, the aspect ratio of the ZSM-48 molecular sieve is 1-2:1; the crystal size of the ZSM-48 molecular sieve is 300-700 nm, preferably 400-600 nm; the specific surface area of the ZSM-48 molecular sieve is 200-280 m 2 / g; the pore volume of the ZSM-48 molecular sieve is 0.2-0.3 mL / g.

[0037] In the present invention, the ZSM-48 molecular sieve has an ellipsoidal morphology with a small aspect ratio of length to width, a high silica-alumina ratio, and a large specific surface area. The content of alkaline metals in the carrier is extremely low, and the obtained hydroisomerization catalyst has higher catalytic activity in the hydroisomerization reaction of liquid hydrocarbons.

[0038] In the present invention, the content of alkaline metal oxides is determined by using a Rigaku 3271E X-ray fluorescence spectrometer (XRF) of Rigaku Corporation, Japan to analyze the composition of the sample. Those skilled in the art can understand that the conventional test accuracy of XRF is 10 ppm. Therefore, when the test result shows 0, it means that the content of alkaline metal oxides is not higher than 0.001 wt%.

[0039] In one embodiment of the present invention, the preparation method of the hydroisomerization catalyst includes the following steps:

[0040] Step 1: Shaping the dry powder of the ZSM-48 molecular sieve to obtain a shaped carrier;

[0041] In the ZSM-48 molecular sieve, the molar ratio of silica to alumina is not less than 40, the specific surface area of the ZSM-48 molecular sieve is not less than 200 m 2 / g, the crystal grains of the ZSM-48 molecular sieve are ellipsoidal, the major axis does not exceed 700 nm, and the aspect ratio is 1-3:1;

[0042] Wherein, based on the mass of the dry powder of the ZSM-48 molecular sieve, the water content of the dry powder of the ZSM-48 molecular sieve is less than 15 wt%;

[0043] Step 2: Subjecting the shaped carrier to ammonium exchange;

[0044] Step 3: Introducing an active metal component onto the product obtained in Step 2 to obtain a hydroisomerization catalyst;

[0045] Wherein, the active metal component is Pt and / or Pd.

[0046] In the present invention, the dried powder of ZSM-48 molecular sieve refers to the dried ZSM-48 molecular sieve powder, and the drying is a conventional operation in the art, as long as the dried powder of ZSM-48 molecular sieve meets the above water content requirements. In the conventional catalyst preparation process in the prior art, generally, the dried and calcined molecular sieve raw powder needs to be subjected to ammonium exchange in a solution first, and then dried, shaped and calcined. On the one hand, the alkali metal content in the carrier after conventional ammonium exchange is generally 0.01-1% by weight, and the catalytic activity is limited; on the other hand, it is difficult to process the molecular sieve raw powder directly after ammonium exchange. The inventors of the present invention found in the research that by first shaping the dried powder of ZSM-48 molecular sieve and then performing ammonium exchange, the alkali metal content in the carrier can be significantly reduced and the catalytic activity of the catalyst can be improved.

[0047] In the present invention, the test method for water content is as follows: Take the dried powder of ZSM-48 molecular sieve with a mass of M and place it in an oven, dry it at 105-110 °C for about 6-8 h until the sample weight no longer changes, weigh the dried sample, denoted as M after drying, and the water content of the dried powder of ZSM-48 molecular sieve can be calculated.

[0048] Water content (wt%) = (M - M after drying) / M × 100%.

[0049] In the present invention, preferably, the preparation method of the ZSM-48 molecular sieve includes the following steps:

[0050] (1) Provide a mixture containing a silicon source, an alkali source, an aluminum source, a template agent, water, a molecular sieve mother liquor and seeds;

[0051] (2) Carry out a crystallization reaction on the mixture; the conditions of the crystallization reaction include: reacting at 20 °C - 50 °C for 1-20 h, reacting at 50 °C - 80 °C for 1-34 h, and then reacting at 80 °C - 180 °C for 1-70 h;

[0052] (3) Carry out solid-liquid separation on the mixture obtained by the crystallization reaction in step (2) to obtain ZSM-48 molecular sieve and a molecular sieve mother liquor, and the molecular sieve mother liquor is returned to step (1);

[0053] This method may also optionally include step (4), and step (4) includes: acidifying and depositing the molecular sieve mother liquor, and then carrying out solid-liquid separation, and the obtained filtrate is returned to step (1);

[0054] The mass percentage of the added seeds in step (1) based on the mass of the silicon source is not less than 10%, and the silicon source is calculated as SiO2.

[0055] According to the present invention, the ZSM-48 molecular sieve is prepared by recycling the molecular sieve mother liquor and introducing seeds, which is beneficial to the formation of small crystal grains. In the present invention, through a crystallization process at three different temperatures, the progress and temperature of the crystallization reaction are strictly controlled. Compared with the prior art, by setting a crystallization reaction process at a low temperature, it helps to control the growth of crystal grains.

[0056] In the present invention, those skilled in the art can understand that the above step (3) or steps (3) and (4) can be arbitrarily selected to obtain the molecular sieve mother liquor. When the method provided by the present invention includes step (4), those skilled in the art can understand that the filtrate provides at least part of the molecular sieve mother liquor described in step (1). By adopting the above preferred preparation method, through the way of recycling the molecular sieve mother liquor and introducing seeds, it is beneficial to the formation of small crystal grains.

[0057] In the present invention, the proportions of the raw materials in step (1) can be adjusted according to actual needs. In order to improve the performance of the molecular sieve in the ZSM-48 molecular sieve precursor, and thus further improve the catalytic performance of the catalyst, preferably, the composition of each component in the mixture described in step (1) calculated by molar amount satisfies the following relationship:

[0058] R / SiO2 = 0.01 - 0.4, preferably 0.01 - 0.08;

[0059] M + / SiO2 = 0.01 - 0.4, preferably 0.1 - 0.2;

[0060] Al2O3 / SiO2 = 0 - 0.02, preferably 0.01 - 0.015;

[0061] H2O / SiO2 = 5 - 30, preferably 5 - 20;

[0062] Among them, SiO2 refers to SiO2 in the silicon source, R represents the template agent, and M + represents the base source.

[0063] According to the present invention, preferably, the conditions of the crystallization reaction in step (2) include: reacting at 20°C - 50°C for 6 - 20 h, reacting at 50°C - 80°C for 12 - 34 h, and then reacting at 80°C - 180°C for 48 - 70 h.

[0064] In the present invention, the amount of seeds used is relatively large. Preferably, the mass percentage of the seeds added in step (1) to the mass of the silicon source is 10 - 30%, preferably 20 - 30%; by adopting the above preferred implementation manner, it is beneficial to form more crystal nuclei, and the prepared molecular sieve has the characteristics of small crystal grains.

[0065] According to the present invention, preferably, in the mixture in step (1), the amount of the molecular sieve mother liquor is less than that of water. Further preferably, the mass percentage of the added molecular sieve mother liquor in step (1) in the total amount of the molecular sieve mother liquor and water in step (1) is not more than 50%, more preferably 10-30%. In the above preferred cases, it is helpful to form molecular sieves with small crystal grains and high specific surface area.

[0066] According to the present invention, preferably, in step (4), the acidification deposition includes: adding an acid to the molecular sieve mother liquor and adjusting the pH value to 5-7, preferably 5-6.5.

[0067] Preferably, the time of the acidification deposition is 0.5-4h.

[0068] In the present invention, for the selection of the silicon source, alkali source, aluminum source, and template agent in step (1), the scope is relatively wide, and the above raw materials are all conventional selections in the art. The above raw materials generally should be mixed into a uniform gel by corresponding means, for example, they can be mixed by stirring.

[0069] According to the present invention, preferably, the silicon source is selected from at least one of silica sol, precipitated silica, fumed silica, water glass, and tetraethyl orthosilicate; more preferably silica sol.

[0070] According to the present invention, preferably, the alkali source is selected from alkaline metal salts, preferably at least one of sodium hydroxide, potassium hydroxide, and calcium hydroxide; more preferably sodium hydroxide.

[0071] According to the present invention, preferably, the aluminum source is selected from at least one of pseudo-boehmite, aluminum sulfate, aluminum isopropoxide, and sodium aluminate; more preferably pseudo-boehmite.

[0072] According to the present invention, preferably, the template agent is selected from at least one of ethylenediamine, 1,3-propanediamine, 1,4-butanediamine, 1,5-pentanediamine, 1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonanediamine, hexamethylammonium bromide, hexamethylammonium chloride, and hexamethylammonium hydroxide; more preferably at least one of 1,6-hexanediamine, hexamethylammonium bromide, hexamethylammonium chloride, and hexamethylammonium hydroxide.

[0073] In the present invention, preferably, the seed crystal is a ZSM-48 molecular sieve seed crystal, and the molar ratio of silicon oxide to aluminum oxide in the ZSM-48 molecular sieve seed crystal is not less than 40, preferably 45-500. The silicon-aluminum ratio in the ZSM-48 molecular sieve seed crystal mainly depends on the feeding of the silicon source and aluminum source in the raw materials and the preparation method.

[0074] In the XRD diffraction pattern of the calcined ZSM-48 molecular sieve raw powder synthesized by existing technical methods, the positions of the diffraction peaks generally occur at 2θ angles of 7.5°, 21.2°, 22.8°, and 31.3°. Among them, the diffraction peak at 21°-22° is the highest, while the diffraction peak at 7°-8° has a relatively weak intensity. The researchers of the present invention found that by using a specific synthesis method, the preferred ZSM-48 molecular sieve seeds of the present invention can be prepared. In the X-ray diffraction pattern of the calcined product, the relative peak height of the diffraction peak at 2θ angles of 7°-8° is significantly higher than that of the diffraction peak at 7°-8° in the molecular sieve obtained by the prior art. Preferably, in the X-ray diffraction pattern of the calcined ZSM-48 molecular sieve seeds, taking the peak height of the diffraction peak at 2θ angles of 21°-22° as the reference value, the peak height of the diffraction peak at 2θ angles of 7°-8° is not less than 70% of the reference value, preferably 75%-135%. For example, the lower limit of the peak height range of the diffraction peak at 7°-8° can be 75%, 80%, 90%, etc. of the reference value, and the upper limit of the peak height range of the diffraction peak at 7°-8° can be 135%, 120%, 110%, 100%, etc. of the reference value. Due to the influence of factors such as samples and instruments, there may be a deviation of ±0.5° in the specific peak position of 2θ angle in the present invention. The purpose of the calcination is to remove impurities such as template agents in the molecular sieve raw powder to obtain a more accurate XRD characterization result, and it will not have a substantial impact on the diffraction peaks in the XRD pattern of the molecular sieve itself. Therefore, the calcination conditions are based on removing impurities. For example, it can be calcined at 400-700°C for 1-8h. In the present invention, the ZSM-48 molecular sieve seeds prepared in the preparation examples were calcined at 600°C for 4h before characterization.

[0075] In one embodiment of the present invention, the forming in step one includes: mixing the dry powder of ZSM-48 molecular sieve, a binder, and an auxiliary agent, and then performing forming and roasting;

[0076] The auxiliary agent is an inorganic acid, preferably nitric acid and / or hydrochloric acid;

[0077] The binder is selected from at least one of alumina, silica, pseudoboehmite, and silica sol, preferably pseudoboehmite.

[0078] In one embodiment of the present invention, relative to 100 parts by weight of the dry powder of ZSM-48 molecular sieve, the dosage of the binder is 20-60 parts by weight, and the dosage of the auxiliary agent is 2-20 parts by weight;

[0079] The roasting conditions include: the roasting temperature is 300-600°C, and the roasting time is 2-10h.

[0080] In one embodiment of the present invention, the ammonium exchange in step two includes: contacting the formed carrier with an aqueous solution of an ammonium salt;

[0081] The conditions for ammonium exchange include: the temperature is 70 - 120 °C, preferably 80 - 100 °C; the time is 1 - 8 h, preferably 2 - 5 h.

[0082] The concentration of the ammonium salt in the aqueous solution of the ammonium salt is 0.01 - 1 mol / L, preferably 0.1 - 1 mol / L.

[0083] The ammonium salt is selected from at least one of ammonium nitrate, ammonium sulfate, ammonium chloride, and ammonium acetate.

[0084] In one embodiment of the present invention, the method for introducing the active metal component in step three includes: impregnating the product in step two with a solution of a soluble compound containing the active metal component, and then performing drying and calcination to obtain the hydroisomerization catalyst;

[0085] The soluble compound containing the active metal component is selected from at least one of tetraamminepalladium nitrate, tetraamminepalladium acetate, dichlorotetraamminepalladium, tetraammineplatinum nitrate, tetraammineplatinum acetate, and dichlorotetraammineplatinum;

[0086] The temperature for drying is 80 - 120 °C, and the time for drying is 2 - 6 hours;

[0087] The temperature for calcination is 400 - 500 °C, and the time for calcination is 2 - 6 hours.

[0088] The hydroisomerization catalyst described in the present invention is a reduced-state hydroisomerization catalyst and has good isomerization selectivity. When in use, the metal active component of the hydroisomerization catalyst is in a reduced state. Therefore, the preparation method further includes: under a hydrogen atmosphere, performing reduction activation on the hydroisomerization catalyst obtained in step three, and the reduction activation process can be carried out in a conventional manner in the art. Preferably, the reduction temperature is 300 - 500 °C, and the reduction time is 2 - 6 h.

[0089] The preferred preparation method of the hydroisomerization catalyst of the present invention has a short preparation process and simple operation. Based on the ZSM-48 molecular sieve with a specific structure, through the method of forming first and then ammonium exchange, the post-treatment difficulty is low. At the same time, the alkali metal content in the catalyst is extremely low, and the obtained hydroisomerization catalyst has higher catalytic activity in the hydroisomerization reaction of liquid hydrocarbons.

[0090] In one embodiment of the present invention, the hydroisomerization reaction effluent obtained in step (3) and the hydroisomerization reaction effluent obtained in step (4) enter a separator for gas-liquid separation to obtain a liquid stream and a gas stream. The obtained gas stream is recycled, and the obtained liquid stream enters a fractionating tower for fractionation to obtain jet fuel. The obtained jet fuel is almost entirely composed of saturated alkanes, has stable properties, and meets the requirements of HEFA-SPK in No. 3 jet fuel.

[0091] The features of the present invention are as follows:

[0092] (1) In the present invention, the oil and fat raw materials are subjected to hydrotreating and hydroisomerization, and the obtained diesel fraction after fractionation is subjected to further hydroisomerization and moderate cracking to obtain high-quality jet fuel in high yield. Moreover, the bio-jet fuel prepared by the method of the present invention is composed entirely of saturated alkanes, has stable properties, and meets the requirements of HEFA-SPK in No. 3 jet fuel.

[0093] (2) The preferred hydroisomerization catalyst of the present invention has higher catalytic activity in the hydroisomerization reaction of liquid hydrocarbons, and can significantly improve the yield of bio-jet fuel. BRIEF DESCRIPTION OF THE DRAWINGS

[0094] Figure 1 Schematic flow diagram of one embodiment of the method for producing jet fuel from oil and fat raw materials provided by the present invention;

[0095] Figure 2 is the X-ray diffraction pattern of the seed crystal A1 obtained in Preparation Example 1-1 after calcination;

[0096] Figure 3 is the X-ray diffraction pattern of the seed crystal A3 obtained in Preparation Example 1-3 after calcination;

[0097] Figure 4 is the SEM image of the ZSM-48 molecular sieve obtained in Preparation Example 2-1. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0098] The present invention will be further described below with reference to the accompanying drawings, but the present invention is not limited thereto.

[0099] Figure 1 is the schematic flow diagram of one embodiment of the method for producing jet fuel from oil and fat raw materials provided by the present invention. As Figure 1 shown, the oil and fat raw material 1, fresh hydrogen 2 and recycle hydrogen 24 enter the heating furnace 3 together and are heated to the reaction temperature required. The materials at the outlet of the heating furnace enter the fixed-bed hydrotreating reactor 4 in the hydrotreating reaction zone, and react with the hydrotreating catalyst under hydrotreating reaction conditions to obtain the hydrotreating reaction effluent. The obtained hydrotreating reaction effluent enters the hot high-pressure separator 5 for gas-liquid separation. The obtained gas-phase stream enters the cold high-pressure separator 6 for further gas-liquid separation. The water 9 separated by the cold high-pressure separator 6 is discharged from the device. The separated gas-phase stream 12 is recycled after being pressurized by the recycle hydrogen compressor 13 after treatment. The liquid-phase stream 7 obtained from the hot high-pressure separator 5 and the liquid-phase stream 8 obtained from the cold high-pressure separator 6 enter the first hydroisomerization reaction zone together as liquid hydrocarbons.

[0100] The obtained liquid hydrocarbons, fresh hydrogen 10 and recycled hydrogen 16 enter the hydroisomerization reactor 11 of the first hydroisomerization reaction zone together, and react with a hydroisomerization catalyst under the first hydroisomerization reaction conditions to obtain a hydroisomerization reaction effluent 14. The hydroisomerization reaction effluent 14 enters a high-pressure separator 15 for gas-liquid separation. The obtained gas-phase stream is recycled back to the hydroisomerization reactor 11 as recycled hydrogen 16, and the obtained liquid-phase stream 17 enters a fractionating tower 18 for fractionation to obtain a naphtha fraction 19, a jet fuel fraction 20 and a diesel fraction 21. The obtained diesel fraction 21 can be recycled back to the inlet of the hydroisomerization reactor 11, or enter the hydroisomerization reactor 22 of the second hydroisomerization reaction zone together with fresh hydrogen 25, and react with a hydroisomerization catalyst under the second hydroisomerization reaction conditions to obtain a hydroisomerization reaction effluent 23, and enter the high-pressure separator 15 together with the hydroisomerization reaction effluent 14.

[0101] The following examples will further illustrate the present invention, but should not be construed as limiting the present invention.

[0102] The hydroisomerization catalyst used in the examples and comparative examples was prepared by the following process.

[0103] In the following preparation examples and preparation comparative examples, a Bruker D5005 diffractometer was used to perform XRD characterization on the samples, with CuKα radiation (λ = 0.154 nm), a tube voltage of 40 kV, a tube current of 30 mA, a scanning range of 5° - 35°, a step size of 0.013°, and 1 step per second. A Hitachi S-4800 scanning electron microscope (SEM) was used to characterize the morphology and size of the samples, with an acceleration voltage of 20 kV.

[0104] A Rigaku 3271E X-ray fluorescence spectrometer (XRF) was used to determine the composition of the samples, including the content of basic metal oxides. The sample preparation method was the tablet pressing method, and the measurement conditions were an end-window rhodium target, a tube voltage of 50 kV, and a tube current of 50 mA.

[0105] The mesoporous structure parameters of the products, such as specific surface area and pore volume, were measured by nitrogen adsorption and the BET method.

[0106] The following preparation examples are used to illustrate the preparation of seeds.

[0107] Preparation Example 1-1

[0108] Aluminum sulfate, hexamethyldiamine hydroxide (HMOH), sodium hydroxide, and deionized water were mixed in a certain proportion, and silica sol was added after stirring for 30 minutes. The molar ratio of various substances was n(Al2O3):(HMOH):n(Na +): n(H2O): n(SiO2) = 0.01:0.03:0.3:8:1. The mixture was transferred to a crystallization kettle and crystallized for 6 h under stirring at room temperature with a stirring speed of 400 rpm; then it was crystallized at 80 °C for 24 h, and then heated to 180 °C and crystallized for 48 h. After crystallization, filtration was carried out, and the solid product was dried at 120 °C for 6 h. The obtained product was seed A1. After crystallization, filtration and drying, the obtained product was seed A1. The XRD diffraction peaks of seed A1 after calcination at 600 °C for 4 h are shown in Figure 1 , and the peak height of the diffraction peak at 7° - 8° was 108% of the peak height of the diffraction peak at 21° - 22°. The XRF analysis results and data such as specific surface area are shown in Table 1.

[0109] Preparation Example 1-2

[0110] Sodium aluminate, hexamethylenediamine chloride (HMCl), sodium hydroxide, and deionized water were mixed in a certain ratio, and after stirring for 30 min, silica sol was added. The molar ratio of various substances was n(Al2O3):(HMCl):n(Na + ):n(H2O):n(SiO2) = 0.004:0.03:0.3:21:1. The mixture was transferred to a crystallization kettle and crystallized for 12 h under stirring at room temperature with a stirring speed of 350 rpm; it was crystallized at 60 °C for 12 h and at 160 °C for 48 h. After crystallization, filtration was carried out, and the product was dried at 120 °C for 6 h. After crystallization, filtration and drying, the obtained product was seed A2. In the XRD diffraction peaks of seed A2 after calcination at 600 °C for 4 h, the peak height of the diffraction peak at 7° - 8° was 115% of the peak height of the diffraction peak at 21° - 22°. The XRF analysis results and data such as specific surface area are shown in Table 1.

[0111] Preparation Example 1-3

[0112] Sodium aluminate, hexamethylenediamine chloride (HMCl), sodium hydroxide, and deionized water were mixed in a certain ratio, and after stirring for 30 min, silica sol was added. The molar ratio of various substances was n(Al2O3):(HMCl):n(Na + ):n(H2O):n(SiO2) = 0.004:0.03:0.3:21:1. The mixture was transferred to a crystallization kettle and crystallized for 12 h under stirring at room temperature with a stirring speed of 350 rpm; it was crystallized at 170 °C for 60 h. After crystallization, filtration and drying were carried out, and the obtained product was seed A3. The XRD of seed A3 after calcination at 600 °C for 4 h is shown in Figure 2 , and the peak height of the diffraction peak at 7° - 8° was 63% of the peak height of the diffraction peak at 21° - 22°. The XRF analysis results and data such as specific surface area are shown in Table 1.

[0113] The following preparation examples are used to illustrate the preparation of ZSM-48 molecular sieve.

[0114] Preparation Example 2-1

[0115] (1) Mix aluminum sulfate, hexamethyldiamine chloride (HMCl), sodium hydroxide, and deionized water containing molecular sieve mother liquor in a certain ratio, stir for 30 minutes, and then add silica sol. The molar ratios of various substances are n(Al2O3):(HMCl):n(Na + ):n(H2O):n(SiO2) = 0.01:0.03:0.3:10:1. The mass percentage of the added molecular sieve mother liquor in the total mass of the molecular sieve mother liquor and water described in step (1) is 30%, and ZSM-48 seed crystal A1 with 25% of the added SiO2 mass is added;

[0116] (2) Transfer the above mixture into a crystallization kettle, stir at room temperature for 6 hours, crystallize at 80 °C for 24 hours, and crystallize at 170 °C for 48 hours;

[0117] (3) After crystallization, filter, dry at 120 °C for 6 hours to obtain the dry powder Z-1 of ZSM-48 molecular sieve, and return the molecular sieve mother liquor to step (1); after testing, the water content of Z-1 is 5 wt%.

[0118] The XRF analysis results of the silicon-aluminum ratio of Z-1 and data such as specific surface area are shown in Table 1, and the scanning electron microscope pictures are shown in Figure 3 , and its morphology is ellipsoidal, the major axis of the particles is 300 - 700 nm, and the ratio of the major axis to the minor axis is about 1.1 - 1.4:1.

[0119] Preparation Example 2-2

[0120] (1) Mix sodium aluminate, hexamethyldiamine chloride (HMCl), sodium hydroxide, and deionized water containing molecular sieve mother liquor in a certain ratio, stir for 30 minutes, and then add silica sol. The molar ratios of various substances are n(Al2O3):(HMCl):n(Na + ):n(H2O):n(SiO2) = 0.004:0.03:0.3:20:1, the mass percentage of the added molecular sieve mother liquor in the total mass of the molecular sieve mother liquor and water described in step (1) is 20%, and ZSM-48 seed crystal A2 with 15% of the added SiO2 mass is added;

[0121] (2) Transfer the above mixture into a crystallization kettle, crystallize at 40 °C for 12 hours, crystallize at 80 °C for 10 hours, and crystallize at 170 °C for 48 hours;

[0122] (3) After crystallization, filter, dry at 120 °C for 6 hours to obtain the dry powder of ZSM-48 molecular sieve Z-2, and return the molecular sieve mother liquor to step (1); after testing, the water content of Z-2 is 6 wt%;

[0123] The XRF analysis results of the silicon-aluminum ratio of Z-2, as well as data such as specific surface area, are shown in Table 1. Its morphology is ellipsoidal, with the major axis of the particles being 300 - 600 nm, and the ratio of the major axis to the minor axis being approximately 1.1 - 1.4:1.

[0124] Comparative Preparation Example 1

[0125] (1) Mix aluminum sulfate, hexamethyldiamine chloride (HMCl), sodium hydroxide, and deionized water containing the molecular sieve mother liquor in a certain ratio, stir for 30 minutes, and then add silica sol. The molar ratios of various substances are n(Al2O3):(HMCl):n(Na + ):n(H2O):n(SiO2) = 0.0125:0.03:0.3:30:1. Add 25% of the mass of SiO2 of ZSM-48 seed crystal A3. The mass percentage of the added molecular sieve mother liquor in the total mass of the molecular sieve mother liquor and water described in step (1) is 20%;

[0126] (2) Transfer the above mixture into a crystallization kettle, stir at room temperature for 6 hours, crystallize at 80 °C for 24 hours, and crystallize at 170 °C for 48 hours;

[0127] (3) After crystallization, filter, dry at 120 °C for 6 hours to obtain the dry powder of ZSM-48 molecular sieve DZ-1, and return the molecular sieve mother liquor to step (1); after testing, the water content of DZ-1 is 8 wt%;

[0128] The XRF analysis results of DZ-1, as well as data such as specific surface area, are shown in Table 1. Its morphology is rod-shaped, and the ratio of the major axis to the minor axis is approximately 7:1.

[0129] Table 1

[0130]

[0131] The following preparation examples are used to illustrate the preparation of the hydroisomerization catalyst.

[0132] Preparation Example 3-1

[0133] Mix 70 g of the Z-1 sample from Preparation Example 2-1 with 40 g of pseudoboehmite on a dry basis and 2 g of nitric acid solution, form into pellets, and calcine at 580 °C for 3 hours. Then place the carrier strips in a 0.5 M ammonium chloride solution and exchange at 90 °C for 2 hours. Take out the carrier strips, dry, and measure the sodium oxide content. The results are shown in Table 2.

[0134] Platinum dichloride tetraammine (with a Pt mass fraction of 57.3%) was poured into 100 g of deionized water and stirred until homogeneous. 100 g of the support was then poured into the above solution and impregnated at room temperature for 4 hours. Subsequently, the above catalyst precursor was dried at 120 °C for 4 hours. Then it was calcined under a flowing air stream at a calcination temperature of 450 °C for 4 hours. The semi-finished catalyst was then placed in a hydrogen atmosphere and reduced at 400 °C for 4 hours to obtain the catalyst. The obtained hydroisomerization catalyst was named CAT-1. In terms of elements, the Pt loading in the catalyst was 0.5 wt%.

[0135] Preparation Example 3-2

[0136] According to the method of Preparation Example 3-1 and the same catalyst composition, except that Z-2 of Preparation Example 2-2 was used to replace Z-1. After ammonium exchange, the support strips were taken out and dried, and the sodium oxide content was measured. The results are shown in Table 2. The obtained hydroisomerization catalyst was named CAT-2.

[0137] Comparative Preparation Example 3-1

[0138] According to the method of Preparation Example 3-1 and the same catalyst composition, except that DZ-1 of Comparative Preparation Example 1 was used to replace Z-1. After ammonium exchange, the support strips were taken out and dried, and the sodium oxide content was measured. The results are shown in Table 2. The obtained hydroisomerization catalyst was named DCAT-1.

[0139] Comparative Preparation Example 3-2

[0140] According to the method of Preparation Example 3-1 and the same catalyst composition, except that the Z-1 sample of Preparation Example 2-1 was calcined at 580 °C for 3 h. The obtained solid was first subjected to ammonium exchange and then extruded into strips. The sodium oxide content was measured. The results are shown in Table 2. The obtained hydroisomerization catalyst was named DCAT-2.

[0141] Table 2

[0142]

[0143]

[0144] Example 1

[0145] In this example, waste oil A was used as the oil raw material, and its main properties are shown in Table 3.

[0146] 100 mL of hydrotreating catalyst was loaded in the hydrotreating reaction zone. Its support was alumina. Based on the hydrotreating catalyst and in terms of oxides, the nickel content was 4.2 wt% and the molybdenum content was 26.5 wt%.

[0147] The first hydroisomerization reaction zone is filled with 100 mL of hydroisomerization catalyst CAT-1.

[0148] Waste oil A and hydrogen enter the hydrotreating reaction zone together, and a sulfiding agent SZ is added to waste oil A 54 , the concentration of the sulfiding agent is 0.3 wt%, and under the hydrotreating reaction conditions, it contacts with the sulfided hydrotreating catalyst to carry out the reaction, obtaining a hydrotreating reaction effluent. The hydrotreating reaction conditions are: reaction pressure 6.4 MPa, reaction temperature 310 °C, volume space velocity 1.0 h -1 and hydrogen-oil volume ratio 1000. The obtained hydrotreating reaction effluent is subjected to gas-liquid separation to obtain a liquid hydrocarbon, water and a gas stream. The conversion rate of waste oil A is 100%, the final boiling point temperature of the obtained liquid hydrocarbon is less than 350 °C, the liquid hydrocarbon yield is 83 wt%, and in the obtained liquid hydrocarbon, the sulfur content is 4 μg / g and the nitrogen content is 1 μg / g.

[0149] The obtained liquid hydrocarbon enters the first hydroisomerization reaction zone, and under the first hydroisomerization reaction conditions, it contacts with the hydroisomerization catalyst to carry out the reaction, obtaining a hydroisomerization reaction effluent. The first hydroisomerization reaction conditions are: reaction temperature 330 °C, reaction pressure 6.4 MPa, volume space velocity 1.0 h -1 and hydrogen-oil volume ratio 600. After the hydroisomerization reaction effluent is subjected to gas-liquid separation and liquid-phase fractionation, a naphtha fraction, a jet fuel fraction, and a diesel fraction are obtained, and all the obtained diesel fraction is recycled to the inlet of the first hydroisomerization reaction zone.

[0150] The liquid product yield in the hydroisomerization reaction zone is 98 wt%, the yield of the jet fuel fraction (boiling range 140 - 300 °C) is 72 wt%, and the freezing point of the jet fuel fraction is -44 °C.

[0151] Example 2

[0152] In this example, waste oil B is used as the oil raw material, and the main properties of waste oil B are shown in Table 3.

[0153] The hydrotreating reaction zone is filled with 100 mL of hydrotreating catalyst, its carrier is alumina, and based on oxides and taking the hydrotreating catalyst as the benchmark, the nickel content is 4 wt% and the tungsten content is 28 wt%.

[0154] The first hydroisomerization reaction zone is filled with 100 mL of hydroisomerization catalyst CAT-2.

[0155] The second hydroisomerization reaction zone is filled with 50 mL of hydroisomerization catalyst CAT-2.

[0156] Waste oil B and hydrogen enter the hydrotreating reaction zone together. Dimethyl disulfide, a sulfurizing agent, is added to waste oil B, and the concentration of the sulfurizing agent is 0.25 wt%. Under the hydrotreating reaction conditions, it reacts with the sulfurized hydrotreating catalyst to obtain a hydrotreating reaction effluent. The hydrotreating reaction conditions are as follows: reaction pressure 6.4 MPa, reaction temperature 290 °C, volume space velocity 1.0 h -1 and hydrogen-oil volume ratio 1200. The obtained hydrotreating reaction effluent is subjected to gas-liquid separation to obtain a liquid hydrocarbon, water, and a gas stream. The conversion rate of waste oil B is 100%, the final boiling point temperature of the obtained liquid hydrocarbon is less than 350 °C, the liquid hydrocarbon yield is 82 wt%, and in the obtained liquid hydrocarbon, the sulfur content is 2 μg / g and the nitrogen content is 1 μg / g.

[0157] The obtained liquid hydrocarbon enters the first hydroisomerization reaction zone and reacts with a hydroisomerization catalyst under the first hydroisomerization reaction conditions to obtain a hydroisomerization reaction effluent. The first hydroisomerization reaction conditions are: reaction temperature 335 °C, reaction pressure 6.4 MPa, volume space velocity 1.0 h -1 and hydrogen-oil volume ratio 600. After the hydroisomerization reaction effluent undergoes gas-liquid separation and liquid-phase fractionation, a naphtha fraction, a jet fuel fraction, and a diesel fraction are obtained. All of the obtained diesel fraction enters the second hydroisomerization reaction zone and reacts with a hydroisomerization catalyst under the second hydroisomerization reaction conditions. The second hydroisomerization reaction conditions are: reaction temperature 340 °C, reaction pressure 6.4 MPa, volume space velocity 1.0 h -1 and hydrogen-oil volume ratio 600. The reaction effluent from the second hydroisomerization reaction zone and the reaction effluent from the first hydroisomerization reaction zone are together subjected to gas-liquid separation and liquid-phase fractionation.

[0158] The total liquid product yield of the first and second hydroisomerization reaction zones is 96 wt%, the yield of the jet fuel fraction (boiling range 140 - 300 °C) is 74 wt%, and the freezing point of the jet fuel fraction is -50 °C.

[0159] Comparative Example 1

[0160] This comparative example uses the same raw materials, hydrotreating catalyst, and hydrotreating reaction conditions as in Example 1. The obtained hydrotreating reaction effluent is subjected to gas-liquid separation to obtain a liquid hydrocarbon, water, and a gas stream.

[0161] The obtained liquid hydrocarbon enters a hydroisomerization reactor filled with 100 mL of hydroisomerization catalyst CAT-1, and under the conditions of reaction pressure 4.8 MPa, reaction temperature 330 °C, volume space velocity 1.0 h -1 and hydrogen-oil volume ratio 500, the liquid hydrocarbon undergoes a hydroisomerization reaction. After the hydroisomerization reaction effluent undergoes gas-liquid separation and liquid-phase fractionation, a jet fuel fraction is obtained.

[0162] The liquid product yield in the hydroisomerization reaction zone is 93 wt%, the yield of the jet fuel fraction (boiling range 140 - 300 °C) is 59 wt%, and the freezing point of the jet fuel fraction is -43 °C.

[0163] Comparative Example 2

[0164] This comparative example uses the same raw materials, hydrotreating catalyst, and hydrotreating reaction conditions as in Example 1. The resulting hydrotreating reaction effluent is subjected to gas-liquid separation to obtain a liquid hydrocarbon, water, and gas stream.

[0165] The obtained liquid hydrocarbon enters the hydroisomerization reactor, which is filled with 100 mL of hydroisomerization catalyst DCAT-2. Under the conditions of a reaction pressure of 6.4 MPa, a reaction temperature of 330 °C, a volume hourly space velocity of 0.8 h -1 and a hydrogen-oil volume ratio of 600, the liquid hydrocarbon undergoes a hydroisomerization reaction. After the hydroisomerization reaction effluent is subjected to gas-liquid separation and liquid-phase fractionation, a naphtha fraction, a jet fuel fraction, and a diesel fraction are obtained. All of the obtained diesel fraction is recycled to the inlet of the hydroisomerization reaction zone.

[0166] The liquid product yield in the hydroisomerization reaction zone is 92 wt%, the yield of the jet fuel fraction (boiling range 140 - 300 °C) is 60 wt%, and the freezing point of the jet fuel fraction is -45 °C.

[0167] Comparative Example 3

[0168] This comparative example uses the same raw materials, hydrotreating catalyst, and hydrotreating reaction conditions as in Example 2. The resulting hydrotreating reaction effluent is subjected to gas-liquid separation to obtain a liquid hydrocarbon, water, and gas stream.

[0169] The first hydroisomerization reaction zone is filled with 100 mL of hydroisomerization catalyst DCAT-1.

[0170] The second hydroisomerization reaction zone is filled with 50 mL of hydroisomerization catalyst DCAT-1.

[0171] The obtained liquid hydrocarbon enters the first hydroisomerization reaction zone and reacts with the hydroisomerization catalyst under the first hydroisomerization reaction conditions to obtain a hydroisomerization reaction effluent. The first hydroisomerization reaction conditions are: a reaction temperature of 335 °C, a reaction pressure of 6.4 MPa, a volume hourly space velocity of 1.0 h -1 and a hydrogen-oil volume ratio of 600. After the hydroisomerization reaction effluent is subjected to gas-liquid separation and liquid-phase fractionation, a naphtha fraction, a jet fuel fraction, and a diesel fraction are obtained. All of the obtained diesel fraction enters the second hydroisomerization reaction zone and reacts with the hydroisomerization catalyst under the second hydroisomerization reaction conditions. The second hydroisomerization reaction conditions are: a reaction temperature of 340 °C, a reaction pressure of 6.4 MPa, a volume hourly space velocity of 1.0 h-1 and a hydrogen-oil volume ratio of 600. The reaction effluent of the second hydroisomerization reaction zone and the reaction effluent of the first hydroisomerization reaction zone are subjected to gas-liquid separation and liquid-phase fractionation together.

[0172] The total liquid product yield of the first and second hydroisomerization reaction zones is 92% by weight, the yield of the jet fuel fraction (boiling range 140 - 300 °C) is 62% by weight, and the freezing point of the jet fuel fraction is -50 °C.

[0173] Table 3

[0174] Item Waste oil A Waste oil B <![CDATA[Density (20 °C), g / cm 3 > 917.3 895.1 Sulfur content, μg / g 37 7.2 Nitrogen content, μg / g 34 19 Oxygen content, w% 11.6 10.96 Total acid value, mgKOH / g 22 175

[0175] It can be seen from the examples that by the method of the present invention, by using a highly active hydroisomerization catalyst in the hydroisomerization reaction zone and the method of re-isomerizing the diesel fraction, the yield of jet fuel is effectively increased.

Claims

1. A method for producing jet fuel from oil-based raw materials, comprising: (1) The oil-based raw materials and hydrogen enter a hydrotreating reaction zone, and under hydrotreating reaction conditions, react with a hydrotreating catalyst to obtain a hydrotreating reaction effluent. The active metal components of the hydrotreating catalyst are at least one metal component selected from Group VIII and / or at least one metal component selected from Group VIB. (2) The hydrotreating reaction effluent obtained in step (1) is separated to obtain a liquid hydrocarbon, water, and a gas stream. (3) The liquid hydrocarbon obtained in step (2) enters a first hydroisomerization reaction zone, and under first hydroisomerization reaction conditions, reacts with a hydroisomerization catalyst. After gas-liquid separation and liquid-phase fractionation of the obtained hydroisomerization reaction effluent, a naphtha fraction, a jet fuel fraction, and a diesel fraction are obtained. At least part of the obtained diesel fraction is recycled to the inlet of the first hydroisomerization reaction zone. (4) An optional second hydroisomerization reaction zone is provided. The diesel fraction obtained in step (3) enters the second hydroisomerization reaction zone, and under second hydroisomerization reaction conditions, reacts with a hydroisomerization catalyst. The obtained hydroisomerization reaction effluent and the hydroisomerization reaction effluent of step (3) are subjected to gas-liquid separation and liquid-phase fractionation together. In steps (3) and (4), the hydroisomerization catalyst includes a carrier and an active metal component supported on the carrier. The carrier contains ZSM-48 molecular sieve, the molar ratio of silica to alumina in the ZSM-48 molecular sieve is not less than 40, and the specific surface area of the ZSM-48 molecular sieve is not less than 200 m 2 / g. The crystal grains of the ZSM-48 molecular sieve are ellipsoidal, the major axis does not exceed 700 nm, and the major axis to minor axis ratio is 1-3:1; The active metal components are Pt and / or Pd. In the hydroisomerization catalyst, based on the total amount of the hydroisomerization catalyst, the content of the molecular sieve on a dry basis is 20-80% by weight, and based on the element, the content of the active metal components is 0.1-20% by weight. Wherein, based on the total amount of the carrier, the content of the basic metal oxide in the carrier is not higher than 0.001% by weight.

2. The method according to claim 1, wherein The oil-based raw materials are animal and vegetable oils and / or waste cooking oil.

3. The method according to claim 1, characterized in that, The carrier of the hydrotreating catalyst is selected from one or more of alumina, silica, titanium oxide, and zirconium oxide. The Group VIII metal components are cobalt and / or nickel, and the Group VIB metal components are molybdenum and / or tungsten. Based on the oxide and based on the hydrotreating catalyst, the content of cobalt and / or nickel is 1-10% by weight, and the content of molybdenum and / or tungsten is 10-45% by weight.

4. The method according to claim 1, wherein The hydrotreating reaction conditions are as follows: reaction temperature is 250 - 450 °C, reaction pressure is 3.0 - 10.0 MPa, volumetric space velocity is 0.1 - 10.0 h -1 , and the hydrogen-to-oil volume ratio is 300 - 2000 Nm 3 / m 3 ; The preferred hydrotreating reaction conditions are as follows: reaction temperature 300 - 400 °C, reaction pressure 4.0 - 8.0 MPa, volumetric space velocity 0.5 - 5.0 h -1 , hydrogen-to-oil volume ratio 500 - 1500 Nm 3 / m 3 .

5. The method according to claim 1, characterized in that, In step (2), the hydrotreating reaction effluent enters a separator for gas-liquid separation to obtain a liquid stream, water, and a gas stream. The obtained liquid stream sequentially enters a stripping column for stripping and a dehydration column for dehydration to remove dissolved hydrogen sulfide, ammonia, and water, and obtain a liquid hydrocarbon.

6. The method according to claim 1, wherein The first hydroisomerization reaction conditions and the second hydroisomerization reaction conditions described in step (3) and step (4) are as follows: the reaction temperature is 200 - 500 °C, the reaction pressure is 1.0 - 15.0 MPa, the volume space velocity is 0.1 - 10.0 h -1 , and the hydrogen-to-oil volume ratio is 200 - 1500 Nm 3 / m 3 ; Preferably, the first hydroisomerization reaction conditions and the second hydroisomerization reaction conditions are as follows: reaction temperature is 280 - 450 °C, reaction pressure is 2.0 - 8.0 MPa, volume space velocity is 0.5 - 5.0 h -1 , and the hydrogen-to-oil volume ratio is 300 - 1000 Nm 3 / m 3 .

7. The method according to claim 1, characterized in that The reaction temperature of the second hydroisomerization reaction conditions is 5-30 °C higher than the reaction temperature of the first hydroisomerization reaction conditions.

8. The method according to claim 1, characterized in that, In the hydroisomerization catalyst, based on the total amount of the hydroisomerization catalyst, the content of the molecular sieve on a dry basis is 30-70% by weight, and based on the element, the content of the active metal components is 0.2-10% by weight.

9. The method according to claim 1 or 8, characterized in that, The hydroisomerization catalyst further contains a binder, and the binder is alumina and / or silica. Based on the total amount of the hydroisomerization catalyst, the content of the binder is 20-80% by weight.

10. The method according to claim 1, characterized in that The aspect ratio of the ZSM-48 molecular sieve is 1-2:1; the crystal size of the ZSM-48 molecular sieve is 300-700 nm; the specific surface area of the ZSM-48 molecular sieve is 200-280 m 2 / g; the pore volume of the ZSM-48 molecular sieve is 0.2-0.3 mL / g.

11. The method according to claim 1, characterized in that, The preparation method of the hydroisomerization catalyst includes the following steps: Step one: Shaping the dry powder of ZSM-48 molecular sieve to obtain a shaped carrier. The molar ratio of silica to alumina in the ZSM-48 molecular sieve is not less than 40, and the specific surface area of the ZSM-48 molecular sieve is not less than 200 m 2 / g. The crystal grains of the ZSM-48 molecular sieve are ellipsoidal, with the major axis not exceeding 700 nm and the major axis to minor axis ratio being 1-3:1; Among them, based on the mass of the dried powder of the ZSM-48 molecular sieve, the water content of the dried powder of the ZSM-48 molecular sieve is less than 15% by weight; Step 2: Subject the shaped carrier to ammonium exchange; Step 3: Introduce an active metal component onto the product obtained in Step 2 to obtain a hydroisomerization catalyst; Among them, the active metal component is Pt and / or Pd.

12. The method according to claim 11, wherein The shaping in Step 1 includes: mixing the dried powder of the ZSM-48 molecular sieve, a binder, and an auxiliary agent, and then performing shaping and calcination; The auxiliary agent is an inorganic acid, preferably nitric acid and / or hydrochloric acid; The binder is selected from at least one of alumina, silica, pseudoboehmite, and silica sol, and preferably pseudoboehmite.

13. The method according to claim 12, characterized in that, Relative to 100 parts by weight of the dried powder of the ZSM-48 molecular sieve, the amount of the binder used is 20-60 parts by weight, and the amount of the auxiliary agent used is 2-20 parts by weight; The conditions for the calcination include: the calcination temperature is 300-600 °C, and the calcination time is 2-10 h.

14. The method according to claim 11, wherein The ammonium exchange in Step 2 includes: contacting the shaped carrier with an aqueous solution of an ammonium salt; The conditions for the ammonium exchange include: the temperature is 70-120 °C, and the time is 1-8 h; The concentration of the ammonium salt in the aqueous solution of the ammonium salt is 0.01-1 mol / L; The ammonium salt is selected from at least one of ammonium nitrate, ammonium sulfate, ammonium chloride, and ammonium acetate.

15. The method according to claim 11, wherein The method for introducing the active metal component in Step 3 includes: impregnating the product in Step 2 with a solution containing a soluble compound of the active metal component, and then performing drying and calcination to obtain the hydroisomerization catalyst; The soluble compound containing the active metal component is selected from at least one of tetraamminepalladium nitrate, tetraamminepalladium acetate, dichlorotetraamminepalladium, tetraammineplatinum nitrate, tetraammineplatinum acetate, and dichlorotetraammineplatinum; The temperature for the drying is 80-120 °C, and the drying time is 2-6 hours; The temperature for the calcination is 400-500 °C, and the calcination time is 2-6 hours.

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