Hydrogenation method for preparing bio-jet fuel

Abstract

The invention relates to a hydrogenation method for preparing bio-jet fuel, which comprises the following steps of: reacting grease raw materials in a hydrotreating reaction zone, enabling the obtained liquid hydrocarbon to enter a selective hydrocracking reaction zone for reaction, enabling the obtained selective hydrocracking reaction effluent to directly enter a hydroisomerization reaction zone for reaction, separating the obtained hydroisomerization reaction effluent, and separating the separated hydroisomerization effluent to obtain the bio-jet fuel. The bio-jet fuel is obtained. By adopting the method provided by the invention, the yield of the obtained bio-jet fuel is high, and the property of the bio-jet fuel is stable.

Description

Technical Field

[0001] The present invention relates to a hydrogenation method for preparing bio - jet fuel, and specifically, it is a hydrogenation 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 the carbon dioxide gas emissions while increasing the fuel supply is an important issue faced by 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 the whole life cycle than fossil diesel fuel. Developing biomass fuel is considered to be 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. The transesterification method 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 the low - temperature fluidity but reduces the stability of fatty acid methyl esters. Since the presence of oxygen in fatty acid methyl esters will result in 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 a first hydrogenation reactor and undergo hydrodeoxygenation reaction in the presence of hydrogen in contact with a hydrotreating catalyst; the hydrocarbon liquid - phase stream obtained after the reaction enters an intermediate fractionating tower, and the C16 - C24 fraction obtained by fractionation enters a second hydrogenation reactor from the top, undergoes a selective cracking reaction in the cracking section in the presence of hydrogen, 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 hydrogenation reactor enters a product fractionating tower, and a 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 silicoaluminophosphate 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 hydroisomerization 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 hydrogenation method for preparing bio-jet fuel on the basis of the prior art to solve the problem of low yield of bio-jet fuel in the prior art.

[0009] The hydrogenation method for preparing bio-jet fuel provided by the present invention includes:

[0010] (1) An 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 obtained hydrotreating reaction effluent is separated to obtain a liquid hydrocarbon, water and a gas stream. 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) The liquid hydrocarbon obtained in step (1) enters a selective hydrocracking reaction zone and reacts with a selective hydrocracking catalyst under selective cracking reaction conditions to obtain a selective hydrocracking reaction effluent.

[0012] (3) The selective hydrocracking reaction effluent obtained in step (2) directly enters a hydroisomerization reaction zone and reacts with a hydroisomerization catalyst to obtain a hydroisomerization reaction effluent. The obtained hydroisomerization reaction effluent is subjected to gas-liquid separation and liquid-phase fractionation to obtain bio-jet fuel.

[0013] The hydroisomerization catalyst described above comprises a carrier and an active metal component supported on the carrier. The carrier contains ZSM-48 molecular sieve, in which the molar ratio of silicon oxide to aluminum oxide is not less than 40, the specific surface area of the ZSM-48 molecular sieve is not less than 200 m2 / g, the crystal grains of the ZSM-48 molecular sieve are ellipsoidal, the major axis does not exceed 700 nm and the ratio of the major axis to the minor axis is 1-3:1;

[0014] The active metal component is Pt and / or Pd;

[0015] 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 elements, the content of the active metal component is 0.1-20% by weight;

[0016] 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.

[0017] 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 oil waste that is not suitable for further consumption generated during the processing and edible consumption of animal and vegetable oils. It includes fatty acids, acidulated oil, etc. generated during the production of edible oil from oilseeds; various waste cooking oils such as frying waste oil, kitchen waste oil, and hogwash oil generated from the use of edible oil by households, hotels, the catering industry, and food production enterprises; animal fats by-produced during meat production and processing, and also edible oil that has exceeded its shelf life, etc.

[0018] In one embodiment of the present invention, the hydrotreating reaction conditions are: reaction temperature 250-450 °C, reaction pressure 3.0-10.0 MPa, volume space velocity 0.1-10.0 h -1 , hydrogen-oil volume ratio 300-2000 Nm 3 / m 3 ;

[0019] Preferably, the hydrotreating reaction conditions are: reaction temperature 300-400 °C, reaction pressure 4.0-8.0 MPa, volume space velocity 0.5-5.0 h -1 , hydrogen-oil volume ratio 500-1500 Nm 3 / m 3 .

[0020] In one embodiment of the present invention, the carrier of the hydrotreating catalyst is selected from one or more of alumina, silica, titania, and zirconia. The Group VIII metal component is cobalt and / or nickel, and the Group VIB metal component is molybdenum and / or tungsten. Based on the oxide and taking the hydrotreating catalyst as the reference, 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.

[0021] In order to maintain the sulfided state of the hydrotreating catalyst, it is preferred to add a sulfiding agent to the oil-based raw material, and the concentration of the sulfiding agent is 0.01-0.5% by weight. The sulfiding agent is one or more of H2S, CS2, dimethyldisulfide, methyl sulfide, di-tert-butyl polysulfide (SZ 54 ), n-butyl sulfide, and thiophene.

[0022] The reactor in the hydrotreating reaction zone is a fixed-bed reactor. The reactor can be provided with multiple beds. The reaction temperature rise can be controlled by injecting cold hydrogen between the beds, or by using the circulating oil method, or by using both methods.

[0023] 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. The hydrotreating reaction effluent mainly consists of alkanes with 8-24 carbon atoms, and also includes water, carbon monoxide, carbon dioxide, hydrogen sulfide, ammonia, and hydrogen.

[0024] In one embodiment of the present invention, 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.

[0025] 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.

[0026] 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.

[0027] In step (2) of the present invention, the obtained liquid hydrocarbons enter the selective hydrocracking reaction zone, and under the selective cracking reaction conditions, they contact with the selective hydrocracking catalyst to react, moderately crack the hydrocarbons with high carbon numbers, and retain the hydrocarbons below C18 as much as possible to obtain the selective hydrocracking reaction effluent. In an embodiment of the present invention, in the liquid phase product of the obtained selective hydrocracking reaction effluent, the mass percentage of the fraction with a temperature higher than 310 °C is not more than 50%, preferably the mass percentage of the fraction with a temperature higher than 310 °C is not more than 30%.

[0028] In an embodiment of the present invention, the selective hydrocracking catalyst includes a carrier and an active metal component supported on the carrier. The carrier contains one or more of amorphous silica-alumina, SAPO-11, SAPO-31, SAPO-41, ZSM-22, ZSM-23, and ZSM-48 molecular sieves. The active metal component is selected from one or more of Pt, Pd, Rh, Ru, Ag, and Au. In the selective hydrocracking catalyst, based on the total amount of the selective hydrocracking catalyst, the content of amorphous silica-alumina or molecular sieve on a dry basis is 40-99.9% by weight, and based on the element, the content of the active metal component is 0.1-0.8% by weight, and the rest is alumina.

[0029] The selective hydrocracking catalyst described in the present invention is a reduced-state selective hydrocracking catalyst. When in use, the metal active component of the selective hydrocracking catalyst is in a reduced state. Therefore, before use, the selective hydrocracking catalyst needs to be reduced and activated: under a hydrogen atmosphere, the reduction temperature is 300-500 °C, and the reduction time is 2-6 h.

[0030] In an embodiment of the present invention, the selective hydrocracking reaction conditions are: reaction temperature 250-500 °C, reaction pressure 1.0-15.0 MPa, volume space velocity 0.1-10.0 h -1 ,hydrogen-oil volume ratio 200-1500 Nm 3 / m 3 ,

[0031] Preferably, the selective hydrocracking reaction conditions are: reaction temperature 300-400 °C, reaction pressure 2.0-8.0 MPa, volume space velocity 0.5-5.0 h -1 ,hydrogen-oil volume ratio 300-1000 Nm 3 / m 3 。

[0032] In step (3) of the present invention, the effluent from the selective hydrocracking reaction directly enters the hydroisomerization reaction zone without any separation and reacts in contact with the hydroisomerization catalyst. In one embodiment of the present invention, the hydroisomerization reaction conditions are as follows: reaction temperature 200 - 500 °C, reaction pressure 1.0 - 15.0 MPa, volumetric space velocity 0.1 - 10.0 h -1 , hydrogen-oil volume ratio 200 - 1500 Nm 3 / m 3 ;

[0033] Preferably, the hydroisomerization reaction conditions are: reaction temperature 280 - 380 °C, reaction pressure 2.0 - 8.0 MPa, volumetric space velocity 0.5 - 5.0 h -1 , hydrogen-oil volume ratio 300 - 1000 Nm 3 / m 3 .

[0034] 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 in terms of elements, the content of the active metal component is 0.2 - 10% by weight.

[0035] In one embodiment of the present invention, the hydroisomerization catalyst further contains a binder, and the binder is alumina and / or silica;

[0036] Based on the total amount of the hydroisomerization catalyst, the content of the binder is 20 - 80% by weight.

[0037] 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.

[0038] In the present invention, the ZSM-48 molecular sieve has an ellipsoidal morphology with a small aspect ratio of length to short diameter, a high silicon-aluminum ratio, a large specific surface area, and an extremely low content of alkaline metals in the carrier, and the obtained hydroisomerization catalyst has higher catalytic activity in the hydroisomerization reaction of liquid hydrocarbons.

[0039] In the present invention, the content of the alkaline metal oxide is determined by measuring the composition of a sample using a Rigaku 3271E X-ray fluorescence spectrometer (XRF). 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 indicates that the content of the alkaline metal oxide is not higher than 0.001 wt%.

[0040] In one embodiment of the present invention, the method for preparing the hydroisomerization catalyst comprises the following steps:

[0041] Step 1: Shaping the dry powder of ZSM-48 molecular sieve to obtain a shaped carrier;

[0042] In the ZSM-48 molecular sieve, the molar ratio of silicon oxide to aluminum oxide 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 major axis ratio is 1 - 3:1;

[0043] 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%;

[0044] Step 2: Subjecting the shaped carrier to ammonium exchange;

[0045] Step 3: Introducing an active metal component onto the product obtained in Step 2 to obtain a hydroisomerization catalyst;

[0046] Wherein, the active metal component is Pt and / or Pd.

[0047] In the present invention, the dry powder of the 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 water content requirement of the dry powder of the ZSM-48 molecular sieve is met. In the conventional catalyst preparation process in the prior art, generally, the dried and calcined molecular sieve raw powder needs to be first subjected to ammonium exchange in a solution, 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 wt%, and the catalytic activity is limited; on the other hand, the post-treatment of the molecular sieve raw powder after direct ammonium exchange is more difficult. The inventors of the present invention found in the research that shaping the dry powder of the ZSM-48 molecular sieve first and then performing ammonium exchange can significantly reduce the alkali metal content in the carrier and improve the catalytic activity of the catalyst.

[0048] In the present invention, the method for testing the water content is as follows: Take the dry 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 weight of the sample no longer changes. Weigh the dried sample, denoted as M after drying, and the water content of the dry powder of ZSM-48 molecular sieve can be calculated.

[0049] Water content (wt%) = (M - M after drying) / M × 100%.

[0050] In the present invention, preferably, the method for preparing the ZSM-48 molecular sieve comprises the following steps:

[0051] (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;

[0052] (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;

[0053] (3) Carry out solid-liquid separation on the mixture obtained from the crystallization reaction in step (2) to obtain the ZSM-48 molecular sieve and the molecular sieve mother liquor, and the molecular sieve mother liquor is returned to step (1);

[0054] This method further optionally includes step (4), and step (4) includes: subjecting the molecular sieve mother liquor to acidification deposition, and then carrying out solid-liquid separation, and returning the obtained filtrate to step (1);

[0055] 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.

[0056] According to the present invention, preparing the ZSM-48 molecular sieve by the way of recycling the molecular sieve mother liquor and introducing seeds is beneficial to the formation of small crystals. In the present invention, through a three-stage crystallization process at different temperatures, the progress and temperature of the crystallization reaction are strictly controlled. Compared with the prior art, by setting the crystallization reaction process at a low temperature, it helps to control the growth of crystal grains.

[0057] In the present invention, those skilled in the art can understand that the molecular sieve mother liquor can be obtained by arbitrarily selecting the above step (3) or steps (3) and (4). 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 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 crystals.

[0058] In the present invention, the proportions of the raw materials in step (1) can be adjusted according to actual needs. 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:

[0059] R / SiO2 = 0.01 - 0.4, preferably 0.01 - 0.08;

[0060] M + / SiO2 = 0.01 - 0.4, preferably 0.1 - 0.2;

[0061] Al2O3 / SiO2 = 0 - 0.02, preferably 0.01 - 0.015;

[0062] H2O / SiO2 = 5 - 30, preferably 5 - 20;

[0063] Among them, SiO2 refers to SiO2 in the silicon source, R represents the template agent, and M + represents the base source.

[0064] According to the present invention, preferably, the conditions for 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.

[0065] In the present invention, the amount of the seed crystal is relatively large. Preferably, the mass percentage of the added seed crystal in step (1) in the mass of the silicon source is 10 - 30%, preferably 20 - 30%; adopting the above preferred implementation mode is beneficial to forming more crystal nuclei, and the prepared molecular sieve has the characteristics of small crystal grains.

[0066] According to the present invention, preferably, in the mixture described in step (1), the amount of the molecular sieve mother liquor is less than the amount of water. Further preferably, the mass percentage of the added molecular sieve mother liquor in step (1) in the total mass of the molecular sieve mother liquor and water in step (1) is not more than 50%, and more preferably 10 - 30%. In the above preferred case, it is helpful to form a molecular sieve with small crystal grains and a high specific surface area.

[0067] 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.

[0068] Preferably, the time for the acidification deposition is 0.5 - 4 h.

[0069] In the present invention, the selection ranges of the silicon source, alkali source, aluminum source, and template agent in step (1) are relatively wide, and the above raw materials are all conventional selections in the art. Generally, the above raw materials should be mixed into a homogeneous gel by corresponding means, for example, they can be mixed by stirring.

[0070] 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, it is silica sol.

[0071] 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, it is sodium hydroxide.

[0072] 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, it is pseudo-boehmite.

[0073] 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, it is at least one of 1,6-hexanediamine, hexamethylammonium bromide, hexamethylammonium chloride, and hexamethylammonium hydroxide.

[0074] 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 amounts of the silicon source and aluminum source in the raw materials and the preparation method.

[0075] In the XRD diffraction pattern of the calcined ZSM-48 molecular sieve raw powder synthesized by the existing technical methods at present, the peak positions of the diffraction peaks generally appear 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 adopting 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 ZSM-48 molecular sieve seeds, the relative peak height of the diffraction peak at 2θ angles of 7°-8° is significantly higher than the relative peak height 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 the 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 are calcined at 600°C for 4h before characterization.

[0076] In one embodiment of the present invention, the shaping in step one includes: mixing the dry powder of ZSM-48 molecular sieve, a binder, and an auxiliary agent, and then performing shaping and roasting;

[0077] The auxiliary agent is an inorganic acid, preferably nitric acid and / or hydrochloric acid;

[0078] The binder is selected from at least one of alumina, silica, pseudoboehmite, and silica sol, preferably pseudoboehmite.

[0079] 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;

[0080] The roasting conditions include: the roasting temperature is 300-600°C, and the roasting time is 2-10h.

[0081] In one embodiment of the present invention, the ammonium exchange in step two includes: contacting the shaped carrier with an aqueous solution of an ammonium salt;

[0082] 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.

[0083] 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.

[0084] The ammonium salt is selected from at least one of ammonium nitrate, ammonium sulfate, ammonium chloride, and ammonium acetate.

[0085] 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 drying and calcining to obtain the hydroisomerization catalyst;

[0086] 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;

[0087] The temperature for drying is 80 - 120 °C, and the time for drying is 2 - 6 hours;

[0088] The temperature for calcining is 400 - 500 °C, and the time for calcining is 2 - 6 hours.

[0089] 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, reducing and activating the hydroisomerization catalyst obtained in step three, and the reduction and 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.

[0090] 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, by 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.

[0091] In one embodiment of the present invention, the obtained hydroisomerization reaction effluent enters 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 biojet fuel. The obtained biojet fuel is almost entirely composed of saturated alkanes, has stable properties, and meets the requirements of HEFA-SPK in No. 3 jet fuel.

[0092] The features of the present invention are as follows:

[0093] (1) The present invention can process oil-based raw materials and obtain bio-jet fuel with a high yield. In the present invention, the liquid hydrocarbons obtained by hydrotreating are first subjected to selective hydrocracking to moderately crack the hydrocarbons with high carbon numbers, and then enter the hydroisomerization reaction zone to contact with a highly active hydroisomerization catalyst for reaction. The reaction effluent is separated to obtain bio-jet fuel. Moreover, the bio-jet fuel prepared by the method of the present invention is entirely composed of saturated alkanes, with stable properties and meeting the requirements of HEFA-SPK in No. 3 jet fuel.

[0094] (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 the target product. BRIEF DESCRIPTION OF THE DRAWINGS

[0095] Figure 1 Schematic flow diagram of one implementation mode of the hydrogenation method for preparing bio-jet fuel provided by the present invention;

[0096] Figure 2 X-ray diffraction pattern of the calcined seed crystal A1 obtained in Preparation Example 1-1;

[0097] Figure 3 X-ray diffraction pattern of the calcined seed crystal A3 obtained in Preparation Example 1-3;

[0098] Figure 4 SEM image of the ZSM-48 molecular sieve obtained in Preparation Example 2-1. DETAILED DESCRIPTION OF THE INVENTION

[0099] The present invention will be further described below with reference to the accompanying drawings, but the present invention is not limited thereby.

[0100] Figure 1 It is a schematic flow diagram of one implementation mode of the hydrogenation method for preparing bio-jet fuel provided by the present invention. As Figure 1As shown, the oil-based raw material 1, fresh hydrogen 2, and recycled hydrogen 24 enter the heating furnace 3 together and are heated to the temperature required for the reaction. The material at the outlet of the heating furnace enters the fixed-bed hydrotreating reactor 4 in the hydrotreating reaction zone and reacts 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 from the cold high-pressure separator 6 is discharged from the device, and the separated gas-phase stream 12 is recycled after being pressurized by the recycle hydrogen compressor 13. 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 selective hydrocracking reaction zone together as liquid hydrocarbons.

[0101] The said liquid hydrocarbons, fresh hydrogen 10, and recycled hydrogen 19 enter the selective hydrocracking reactor 11 in the selective hydrocracking reaction zone and react with the selective hydrocracking catalyst under selective cracking reaction conditions to obtain the selective hydrocracking reaction effluent 14 which directly enters the hydroisomerization reactor 15 in the hydroisomerization reaction zone. Under hydroisomerization reaction conditions, it reacts with the hydroisomerization catalyst. The obtained hydroisomerization reaction effluent 16 enters the high-pressure separator 17 for gas-liquid separation. The obtained gas-phase stream is recycled as recycled hydrogen 19, and the obtained liquid-phase stream 18 enters the fractionating tower 20 for fractionation to obtain bio-naphtha 21, bio-jet fuel 22, and biodiesel 23.

[0102] The following examples will further illustrate the present invention, but should not be construed as limiting the present invention.

[0103] The hydroisomerization catalyst used in the examples and comparative examples was prepared by the following process.

[0104] In the following preparation examples and preparation comparative examples, the XRD characterization of the samples was carried out using a Bruker D5005 diffractometer, with CuKα radiation (λ = 0.154 nm), tube voltage 40 kV, tube current 30 mA, scanning range 5° - 35°, step size 0.013°, and 1 step per second. The morphology and size of the samples were characterized using a Hitachi S-4800 scanning electron microscope (SEM) with an acceleration voltage of 20 kV.

[0105] The composition of the samples, including the content of basic metal oxides, was determined using a Rigaku 3271E X-ray fluorescence spectrometer (XRF) of Japan. The sample preparation method was the tablet pressing method, and the measurement conditions were an end-window rhodium target, tube voltage 50 kV, and tube current 50 mA.

[0106] The mesoporous structure parameters of the products, such as specific surface area and pore volume, were measured using nitrogen adsorption and the BET method.

[0107] The following preparation examples are used to illustrate the preparation of seeds.

[0108] Preparation Example 1-1

[0109] Aluminum sulfate, hexamethylenediamine hydroxide (HMOH), sodium hydroxide, and deionized water were mixed in a certain ratio, and after stirring for 30 minutes, silica sol was added. The molar ratios of various substances were 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 at room temperature with stirring for 6 h, and the stirring speed was 400 rpm; then it was crystallized at 80 °C for 24 h, and then heated to 180 °C for crystallization for 48 h. After the crystallization was completed, filtration was carried out, and the solid product was dried at 120 °C for 6 h. The obtained product was seed A1. After filtration and drying after the crystallization was completed, the obtained product was seed A1. The XRD diffraction peaks of seed A1 after calcination at 600 °C for 4 h are shown 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.

[0110] Preparation Example 1-2

[0111] Sodium aluminate, hexamethylenediamine chloride (HMCl), sodium hydroxide, and deionized water were mixed in a certain ratio, and after stirring for 30 minutes, silica sol was added. The molar ratios of various substances were 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 at room temperature with stirring for 12 h, and the stirring speed was 350 rpm; it was crystallized at 60 °C for 12 h and at 160 °C for 48 h. After the crystallization was completed, filtration was carried out, and the product was dried at 120 °C for 6 h. The product obtained after filtration and drying after the crystallization was completed was seed A2. In the XRD diffraction peaks 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.

[0112] Preparation Example 1-3

[0113] Sodium aluminate, hexamethylenediamine chloride (HMCl), sodium hydroxide, and deionized water were mixed in a certain ratio, and after stirring for 30 minutes, silica sol was added. The molar ratios of various substances were 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 with stirring at room temperature, and the stirring speed was 350 rpm; it was crystallized at 170 °C for 60 h. After crystallization, the product obtained by filtration and drying was seed A3. After calcining seed A3 at 600 °C for 4 h, XRD showed Figure 2 that 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.

[0114] The following preparation examples are used to illustrate the preparation of ZSM-48 molecular sieve.

[0115] Preparation Example 2-1

[0116] (1) Aluminum sulfate, hexamethylenediamine chloride (HMCl), sodium hydroxide, and deionized water containing molecular sieve mother liquor were mixed in a certain ratio, and stirred for 30 min, then silica sol was added. The molar ratio of various substances was 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) was 30%, and seed A1 of ZSM-48 accounting for 25% of the added SiO2 mass was added;

[0117] (2) The above mixture was transferred to a crystallization kettle, stirred at room temperature for 6 h, crystallized at 80 °C for 24 h, and crystallized at 170 °C for 48 h;

[0118] (3) After crystallization, it was filtered and dried at 120 °C for 6 h to obtain the dry powder Z-1 of ZSM-48 molecular sieve, and the molecular sieve mother liquor was returned to step (1); after testing, the water content of Z-1 was 5 wt%.

[0119] The XRF analysis results of the silicon-aluminum ratio of Z-1 and data such as specific surface area are shown in Table 1. The scanning electron microscope pictures are shown in Figure 3 which had an ellipsoidal morphology, the major axis of the particles was 300 - 700 nm, and the ratio of the major axis to the minor axis was about 1.1 - 1.4: 1.

[0120] Preparation Example 2-2

[0121] (1) Sodium aluminate, hexamethylenediamine chloride (HMCl), sodium hydroxide, and deionized water containing molecular sieve mother liquor were mixed in a certain ratio, and stirred for 30 min, then 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: 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%. Add ZSM-48 seed crystal A2, which is 15% of the mass of the added SiO2.

[0122] (2) Transfer the above mixture into a crystallization kettle, crystallize at 40 °C for 12 h, crystallize at 80 °C for 10 h, and crystallize at 170 °C for 48 h.

[0123] (3) After crystallization, filter, dry at 120 °C for 6 h to obtain the dried 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%.

[0124] The XRF analysis results of the silicon-aluminum ratio of Z-2 and data such as specific surface area are shown in Table 1. Its morphology is ellipsoidal, the major axis of the particle is 300 - 600 nm, and the ratio of the major axis to the minor axis is about 1.1 - 1.4: 1.

[0125] Comparative Preparation Example 1

[0126] (1) Mix aluminum sulfate, hexamethylenediamine chloride (HMCl), sodium hydroxide, and deionized water containing molecular sieve mother liquor in a certain ratio, stir for 30 min, and then add silica sol. The molar ratio of various substances is n(Al2O3):(HMCl):n(Na + ): n(H2O): n(SiO2) = 0.0125: 0.03: 0.3: 30: 1. Add ZSM-48 seed crystal A3, which is 25% of the mass of the added SiO2. 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%.

[0127] (2) Transfer the above mixture into a crystallization kettle, stir at room temperature for 6 h, crystallize at 80 °C for 24 h, and crystallize at 170 °C for 48 h.

[0128] (3) After crystallization, filter, dry at 120 °C for 6 h to obtain the dried 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%.

[0129] The XRF analysis results of DZ-1 and 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 about 7: 1.

[0130] Table 1

[0131]

[0132]

[0133] The following preparation examples are used to illustrate the preparation of the hydroisomerization catalyst.

[0134] Preparation Example 3-1

[0135] 70 g of the Z-1 sample from Preparation Example 2-1 was mixed with 40 g of pseudo-boehmite on a dry basis and 2 g of nitric acid solution, formed, and calcined at 580 °C for 3 h. Then the carrier strips were placed in a 0.5 M ammonium chloride solution and exchanged at 90 °C for 2 h. The carrier strips were taken out, dried, and the sodium oxide content was measured. The results are shown in Table 2.

[0136] Dichlorotetraammineplatinum (with a Pt mass fraction of 57.3%) was poured into 100 g of deionized water and stirred until homogeneous. 100 g of the carrier was poured into the above solution and impregnated at room temperature for 4 h. Subsequently, the above catalyst precursor was dried at 120 °C for 4 h. Then it was calcined in a flowing air state, with a calcination temperature of 450 °C and a time of 4 h. The obtained semi-finished catalyst was again placed in a hydrogen atmosphere and reduced at 400 °C for 4 h 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%.

[0137] Preparation Example 3-2

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

[0139] Comparative Preparation Example 3-1

[0140] According to the method of Preparation Example 3-1 and the same catalyst composition, except that DZ-1 from Comparative Preparation Example 1 was used to replace Z-1. After ammonium exchange, the carrier strips were taken out, dried, and the sodium oxide content was measured. The results are shown in Table 2. The obtained hydroisomerization catalyst was named DCAT-1.

[0141] Comparative Preparation Example 3-2

[0142] According to the method of Preparation Example 3-1 and the same catalyst composition, except that the Z-1 sample from 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.

[0143] Table 2

[0144]

[0145] Example 1

[0146] In this embodiment, used cooking oil A is used as the raw material, and the main properties of used cooking oil A are shown in Table 3.

[0147] The hydrotreating reaction zone is filled with 100 mL of hydrotreating catalyst, the carrier of which is alumina. Based on the oxide and taking the hydrotreating catalyst as the reference, the content of nickel is 4.2 wt%, and the content of molybdenum is 26.5 wt%.

[0148] The selective hydrocracking reaction zone is filled with 100 mL of selective hydrocracking catalyst, the carrier of which is amorphous silica-alumina. Based on the elements, the content of the active metal component Pt is 0.15 wt%, and the content of Pd is 0.30 wt%.

[0149] The hydroisomerization reaction zone is filled with 100 mL of hydroisomerization catalyst CAT-1.

[0150] Used cooking oil A and hydrogen enter the hydrotreating reaction zone together, and a sulfiding agent SZ is added to used cooking oil A 54 , and the concentration of the sulfiding agent is 0.3 wt%. Under the hydrotreating reaction conditions, it contacts with the sulfided hydrotreating catalyst for reaction to obtain the hydrotreating reaction effluent. The hydrotreating reaction conditions are: reaction pressure 6.4 MPa, reaction temperature 320 °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 liquid hydrocarbons, water and gas streams. The conversion rate of used cooking oil A is 100%, the final boiling point temperature of the obtained liquid hydrocarbons is less than 350 °C, the liquid hydrocarbon yield is 82.5 wt%, the sulfur content in the obtained liquid hydrocarbons is 2 μg / g, the nitrogen content is 1 μg / g, and the fraction with a boiling point greater than 310 °C accounts for 80 wt%.

[0151] The obtained liquid hydrocarbons enter the selective hydrocracking reaction zone. Under the selective hydrocracking reaction conditions, they contact with the selective hydrocracking catalyst for reaction to obtain the selective hydrocracking reaction effluent. The selective hydrocracking reaction conditions are: reaction temperature 355 °C, reaction pressure 5.0 MPa, volume space velocity 1.0 h -1 and hydrogen-oil volume ratio 500. In the liquid phase product of the obtained selective hydrocracking reaction effluent, the fraction with a boiling point less than or equal to 310 °C accounts for 80 wt%.

[0152] The obtained selective hydrocracking reaction effluent directly enters the hydroisomerization reaction zone without separation. Under the hydroisomerization reaction conditions, it contacts with the hydroisomerization catalyst for reaction to obtain the hydroisomerization reaction effluent. The hydroisomerization reaction conditions are: reaction temperature 280 °C, reaction pressure 5.0 MPa, volume space velocity 1.0 h -1 and hydrogen-oil volume ratio 500,

[0153] After the hydroisomerization reaction effluent undergoes gas-liquid separation and liquid-phase fractionation, biojet fuel is obtained.

[0154] The liquid product yield in the hydroisomerization reaction zone is 96 wt%, the yield of biojet fuel (boiling range 140 - 300 °C) is 77.6 wt%, and the freezing point of the biojet fuel is -44 °C.

[0155] Example 2

[0156] In this example, waste cooking oil B is used as the raw material. The main properties of waste cooking oil B are shown in Table 3.

[0157] The hydrotreating reaction zone is filled with 100 mL of hydrotreating catalyst. Its carrier is alumina. Based on the oxide and taking the hydrotreating catalyst as the benchmark, the nickel content is 4.0 wt% and the tungsten content is 28 wt%.

[0158] The selective hydrocracking reaction zone is filled with 100 mL of selective hydrocracking catalyst. Its carrier is amorphous silica-alumina. Based on the elements, the content of the active metal component Pt is 0.15 wt% and the content of Pd is 0.30 wt%.

[0159] The hydroisomerization reaction zone is filled with 100 mL of hydroisomerization catalyst CAT-2.

[0160] Waste cooking oil B and hydrogen enter the hydrotreating reaction zone together. Dimethyl disulfide as a sulfurizing agent is added to waste cooking oil B, and the concentration of the sulfurizing agent is 0.25 wt%. Under the hydrotreating reaction conditions, it contacts with the sulfurized hydrotreating catalyst for reaction to obtain the hydrotreating reaction effluent. The hydrotreating reaction conditions are: reaction pressure 6.4 MPa, reaction temperature 320 °C, volume space velocity 1.0 h -1 and hydrogen-oil volume ratio 1000. The obtained hydrotreating reaction effluent undergoes gas-liquid separation to obtain liquid hydrocarbons, water, and gas streams. The conversion rate of waste cooking oil B is 100%. The final boiling point temperature of the obtained liquid hydrocarbons is less than 350 °C, the liquid hydrocarbon yield is 82.5 wt%, the sulfur content in the obtained liquid hydrocarbons is 7 μg / g, the nitrogen content is 1 μg / g, and the fraction greater than 310 °C accounts for 85 wt%.

[0161] The obtained liquid hydrocarbons enter the selective hydrocracking reaction zone. Under the selective hydrocracking reaction conditions, they contact with the selective hydrocracking catalyst for reaction to obtain the selective hydrocracking reaction effluent. The selective hydrocracking reaction conditions are: reaction temperature 355 °C, reaction pressure 5.0 MPa, volume space velocity 1.0 h -1 and hydrogen-oil volume ratio 500. In the liquid-phase product of the obtained selective hydrocracking reaction effluent, the fraction less than or equal to 310 °C accounts for 75 wt%.

[0162] The obtained selective hydrocracking reaction effluent directly enters the hydroisomerization reaction zone without separation. Under hydroisomerization reaction conditions, it contacts with a hydroisomerization catalyst for reaction to obtain a hydroisomerization reaction effluent. The hydroisomerization reaction conditions are as follows: reaction temperature 290 °C, reaction pressure 5.0 MPa, volume hourly space velocity 1.0 h -1 and hydrogen-oil volume ratio 500,

[0163] After the hydroisomerization reaction effluent undergoes gas-liquid separation and liquid-phase fractionation, biojet fuel is obtained.

[0164] The liquid product yield in the hydroisomerization reaction zone is 94 wt%, the yield of biojet fuel (boiling range 140 - 300 °C) is 74.9 wt%, and the freezing point of the biojet fuel is < -60 °C.

[0165] Comparative Example 1

[0166] This comparative example uses the same raw materials, hydrotreating catalyst, and hydrotreating reaction conditions as in Example 1. The obtained hydrotreating reaction effluent undergoes gas-liquid separation to obtain a liquid hydrocarbon, water, and gas stream.

[0167] The obtained liquid hydrocarbon does not enter the selective hydrocracking reaction zone and all directly enters a hydroisomerization reactor filled with 100 mL of hydroisomerization catalyst CAT-1. Under the conditions of reaction pressure 6.4 MPa, reaction temperature 330 °C, volume hourly 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, biojet fuel is obtained.

[0168] The liquid product yield in the hydroisomerization reaction zone is 97 wt%, the yield of biojet fuel (boiling range 140 - 300 °C) is 58 wt%, and the freezing point of the biojet fuel is -49 °C.

[0169] Comparative Example 2

[0170] The hydroisomerization reaction zone is filled with 100 mL of hydroisomerization catalyst DCAT-2.

[0171] This comparative example uses the same raw materials, hydrotreating catalyst, hydrotreating reaction conditions, selective hydrocracking catalyst, and selective hydrocracking reaction conditions as in Example 1.

[0172] The obtained selective hydrocracking reaction effluent directly enters the hydroisomerization reaction zone without separation. Under hydroisomerization reaction conditions, it contacts with a hydroisomerization catalyst for reaction to obtain a hydroisomerization reaction effluent. The hydroisomerization reaction conditions are as follows: reaction temperature 290 °C, reaction pressure 5.0 MPa, volume hourly space velocity 1.0 h -1 and hydrogen-oil volume ratio 500,

[0173] After the hydroisomerization reaction effluent undergoes gas-liquid separation and liquid-phase fractionation, biojet fuel is obtained.

[0174] The liquid product yield in the hydroisomerization reaction zone is 92 wt%, the yield of biojet fuel (boiling range 140 - 300 °C) is 59 wt%, and the freezing point of the biojet fuel is -43 °C.

[0175] Comparative Example 3

[0176] 100 mL of hydroisomerization catalyst DCAT-1 is loaded in the hydroisomerization reaction zone.

[0177] This comparative example uses the same raw materials, hydrotreating catalyst, hydrotreating reaction conditions, selective hydrocracking catalyst, and selective hydrocracking reaction conditions as in Example 1.

[0178] The obtained selective hydrocracking reaction effluent enters the hydroisomerization reaction zone directly without separation and reacts with the hydroisomerization catalyst under hydroisomerization reaction conditions to obtain the hydroisomerization reaction effluent. The hydroisomerization reaction conditions are: reaction temperature 290 °C, reaction pressure 5.0 MPa, volume space velocity 1.0 h -1 and hydrogen-oil volume ratio 500,

[0179] After the hydroisomerization reaction effluent undergoes gas-liquid separation and liquid-phase fractionation, biojet fuel is obtained.

[0180] The liquid product yield in the hydroisomerization reaction zone is 91 wt%, the yield of biojet fuel (boiling range 140 - 300 °C) is 60 wt%, and the freezing point of the biojet fuel is -41 °C.

[0181] It can be seen from the examples that by the method of the present invention, selective hydrocracking followed by hydroisomerization, and using a highly active hydroisomerization catalyst in the hydroisomerization reaction zone, the yield of biojet fuel is effectively increased.

[0182] Table 3

[0183] Item Food waste oil A Food waste oil B <![CDATA[Density (20 °C), g / cm 3 > 904.8 916 Sulfur content, μg / g 78 55 Nitrogen content, μg / g 81 186 Oxygen content, wt% 12.15 11.2 Total acid value, mgKOH / g 124 32

Claims

1. A hydrogenation method for preparing bio-jet fuel, comprising: (1) An 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 obtained hydrotreating reaction effluent is separated to obtain a liquid hydrocarbon, water, and a gas stream. 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. (2) The liquid hydrocarbon obtained in step (1) enters a selective hydrocracking reaction zone and reacts with a selective hydrocracking catalyst under selective cracking reaction conditions to obtain a selective hydrocracking reaction effluent. (3) The selective hydrocracking reaction effluent obtained in step (2) directly enters a hydroisomerization reaction zone and reacts with a hydroisomerization catalyst to obtain a hydroisomerization reaction effluent. The obtained hydroisomerization reaction effluent is subjected to gas-liquid separation and liquid-phase fractionation to obtain bio-jet fuel. The hydroisomerization catalyst described above comprises a support and an active metal component supported on the support. The support contains ZSM-48 molecular sieve, and 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; The active metal component is Pt and / or Pd. In the hydroisomerization catalyst, based on the total amount of the hydroisomerization catalyst, the content of 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. Wherein, based on the total amount of the carrier, the content of basic metal oxide in the carrier is not higher than 0.001% by weight.

2. 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 , and the hydrogen-to-oil volume ratio is 500 - 1500 Nm 3 / m 3 .

3. The method according to claim 1, wherein 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. 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, characterized in that In step (1), 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 to obtain a liquid hydrocarbon.

5. The method according to claim 1, characterized in that The selective hydrocracking catalyst includes a carrier and an active metal component supported on the carrier. The carrier contains one or more of amorphous silica-alumina, SAPO-11, SAPO-31, SAPO-41, ZSM-22, ZSM-23, and ZSM-48 molecular sieves. The active metal component is selected from one or more of Pt, Pd, Rh, Ru, Ag, and Au. In the selective hydrocracking catalyst, based on the total amount of the selective hydrocracking catalyst, the content of amorphous silica-alumina or molecular sieve on a dry basis is 40 - 99.9% by weight, and based on the element, the content of the active metal component is 0.1 - 0.8% by weight, and the rest is alumina.

6. The method according to claim 1, wherein The selective hydrocracking reaction conditions are as follows: reaction temperature is 250 - 500 °C, reaction pressure is 1.0 - 15.0 MPa, volumetric space velocity is 0.1 - 10.0 h -1 , hydrogen-to-oil volume ratio is 200 - 1500 Nm 3 / m 3 , The preferred selective hydrocracking reaction conditions are: reaction temperature 300 - 400 °C, reaction pressure 2.0 - 8.0 MPa, volumetric space velocity 0.5 - 5.0 h -1 , hydrogen-to-oil volume ratio 300 - 1000 Nm 3 / m 3 .

7. The method according to claim 1, characterized in that, In the liquid-phase product of the obtained selective hydrocracking reaction effluent, the mass percentage of the fraction with a boiling point > 310 °C is not more than 50%, preferably not more than 30%.

8. The method according to claim 1, wherein 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.

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, wherein 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, wherein The method for preparing the hydroisomerization catalyst includes the following steps: Step 1: Shaping the dry powder of ZSM-48 molecular sieve to obtain a shaped carrier; The molar ratio of silicon oxide to aluminum oxide 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 a major axis not exceeding 700 nm and a major axis to minor axis ratio of 1-3:1; Among them, 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% by weight; Step 2: Subjecting the shaped carrier to ammonium exchange; Step 3: Introducing 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 dry powder of ZSM-48 molecular sieve, a binder and an auxiliary agent, and then shaping and calcining; 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, wherein Relative to 100 parts by weight of the dry powder of the 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; 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 drying and calcining 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.

16. The method according to claim 1, wherein The hydroisomerization reaction conditions are as follows: reaction temperature is 200 - 500 °C, reaction pressure is 1.0 - 15.0 MPa, volumetric space velocity is 0.1 - 10.0 h -1 , hydrogen-oil volume ratio is 200 - 1500 Nm 3 / m 3 ; The preferred hydroisomerization reaction conditions are: reaction temperature 280 - 380 °C, reaction pressure 2.0 - 8.0 MPa, volumetric space velocity 0.5 - 5.0 h -1 , hydrogen-to-oil volume ratio 300 - 1000 Nm 3 / m 3 .

17. The method according to claim 1, wherein The oil-based raw material is animal and vegetable oils and / or waste cooking oil.

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