Hydrogenation method for producing bio-jet fuel from grease raw materials

Abstract

A hydrogenation method for producing bio-jet fuel from grease raw materials comprises the following steps: the grease raw materials contact with a hydrotreating catalyst I and / or a hydrotreating catalyst II in a hydrotreating reaction zone for reaction, obtained liquid hydrocarbon light components enter a first hydroisomerization reaction zone, and obtained liquid hydrocarbon heavy components enter a second hydroisomerization reaction zone; and carrying out gas-liquid separation and liquid-phase fractionation on the first hydroisomerization reaction effluent and the second hydroisomerization reaction effluent to obtain the bio-jet fuel. According to different raw materials, the technical scheme of the hydrotreating reaction zone is flexibly adjusted, and 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 more particularly, to 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 carbon dioxide gas emissions while increasing 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 its whole 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 through 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 fractionation tower, and the C16 - C24 fraction obtained by fractionation enters a second hydrogenation reactor from the top and 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 fractionation 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 normal paraffins with 8-24 carbon atoms; (2) under hydroisomerization conditions, contacting the normal paraffins with 8-24 carbon atoms, 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 silicoaluminophosphate molecular sieve, and the metal active component contains one or more 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 hydrogenation method for producing bio-jet fuel from oil and fat 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 hydrogenation method for producing bio-jet fuel from oil and fat raw materials provided by the present invention includes: (1) The oil and fat raw materials and hydrogen enter the hydrotreating reaction zone together and react under hydrotreating reaction conditions in contact with a hydrotreating catalyst I and / or a hydrotreating catalyst II to obtain a hydrotreating reaction effluent. The hydrotreating catalyst I is a single-molybdenum catalyst, and the hydrotreating catalyst II is a multi-metal catalyst.

[0010] (2) The hydrotreating reaction effluent obtained in step (1) is subjected to gas-liquid separation to obtain a liquid hydrocarbon, water and a gas stream. The liquid hydrocarbon is cut to obtain a liquid hydrocarbon light fraction and a liquid hydrocarbon heavy fraction, and the cutting point is 290-310 °C.

[0011] (3) The liquid hydrocarbon light fraction obtained in step (2) enters the first hydroisomerization reaction zone and reacts under the first hydroisomerization reaction conditions in contact with a hydroisomerization catalyst to obtain a first hydroisomerization reaction effluent.

[0012] (4) The liquid hydrocarbon heavy fraction obtained in step (2) enters the second hydroisomerization reaction zone and reacts under the second hydroisomerization reaction conditions in contact with a hydroisomerization catalyst to obtain a second hydroisomerization reaction effluent.

[0013] After the first hydroisomerization reaction effluent and the second hydroisomerization reaction effluent are subjected to gas-liquid separation and liquid-phase fractionation, biojet fuel is obtained.

[0014] The hydroisomerization catalyst described in step (3) and step (4) includes a support and an active metal component supported on the support. The support 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, the major axis does not exceed 700 nm, and the major axis ratio is 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 support, the content of the basic metal oxide in the support 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 the transesterification method of vegetable oils and / or animal fats. The waste cooking oil is oil and fat waste that is not suitable for further consumption generated in the processing of animal and vegetable oils and edible consumption. It includes fatty acids, acidified 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 residential households, hotels, the catering industry, and food production enterprises; animal fats by-produced in meat production and processing, and also edible oil beyond the shelf life, etc.

[0019] According to the different properties of the oil and fat raw materials, the present invention can select a technical solution for the hydrotreating reaction zone.

[0020] In one embodiment of the present invention, when the sulfur content and nitrogen content in the oil and fat raw materials are both <50 μg / g, the hydrotreating reaction zone is filled with hydrotreating catalyst I. In the obtained liquid hydrocarbon, the content of even-carbon-chain alkanes is not less than 90% by weight.

[0021] In one embodiment of the present invention, when the sulfur content and nitrogen content in the oil-based raw material are both between 50 and 150 μg / g, a hydrotreating catalyst I and a hydrotreating catalyst II are loaded in the hydrotreating reaction zone, and the loading volume ratio of the hydrotreating catalyst I to the hydrotreating catalyst II is 1:9 - 9:1, preferably 2:8 - 8:2. In the obtained liquid hydrocarbon, the content of even-carbon-chain alkanes is not less than 60% by weight.

[0022] In one embodiment of the present invention, when the sulfur content and nitrogen content in the oil-based raw material are both > 150 μg / g, a hydrotreating catalyst II is loaded in the hydrotreating reaction zone. In the obtained liquid hydrocarbon, the content of even-carbon-chain alkanes is not less than 30% by weight.

[0023] In one embodiment of the present invention, the carrier of the hydrotreating catalyst I is selected from one or more of alumina, silica, titanium oxide, and zirconium oxide, and the active metal of the hydrotreating catalyst I is molybdenum. Calculated as the oxide and based on the hydrotreating catalyst I, the content of molybdenum is 10% to less than 17% by weight.

[0024] In one embodiment of the present invention, the carrier of the hydrotreating catalyst II is selected from one or more of alumina, silica, titanium oxide, and zirconium oxide, and the active metals of the hydrotreating catalyst II are two or more metals selected from cobalt, nickel, molybdenum, and tungsten; calculated as the oxide and based on the hydrotreating catalyst II, 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.

[0025] 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 ;

[0026] 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 is 500 - 1500 Nm 3 / m 3 。

[0027] 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, dimethyl disulfide, methyl sulfide, di-tert-butyl polysulfide (SZ 54 ), n-butyl sulfide, and thiophene.

[0028] 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 can be controlled by injecting cold hydrogen between the beds, or by using recycled oil, or by using both methods.

[0029] In the hydrotreating reaction zone, the oil and fat raw materials mainly undergo olefin saturation and hydrodeoxygenation reactions. Among them, the oxygen in the oil and fat raw materials is mainly removed in the form of water production. The hydrotreating reaction effluent mainly consists of alkanes with carbon numbers from 8 to 24, and also includes water, carbon monoxide, carbon dioxide, hydrogen sulfide, ammonia, and hydrogen, etc.

[0030] 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. The obtained liquid hydrocarbon is cut to obtain a light fraction of the liquid hydrocarbon and a heavy fraction of the liquid hydrocarbon, and the cutting point is 290 - 310 °C.

[0031] The gas stream can be directly recycled or can obtain 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.

[0032] 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.

[0033] In step (3) of the present invention, the light fraction of the 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. In step (4) of the present invention, the heavy fraction of the liquid hydrocarbon enters the second hydroisomerization reaction zone and reacts with a hydroisomerization catalyst under the second hydroisomerization reaction conditions to obtain a second hydroisomerization reaction effluent.

[0034] In one embodiment of the present invention, the first hydroisomerization reaction conditions and the second hydroisomerization reaction conditions in step (3) and step (4) are: reaction temperature 200 - 500 °C, reaction pressure 1.0 - 10.0 MPa, volumetric space velocity 0.1 - 10.0 h -1 , hydrogen-oil volume ratio 200 - 1500 Nm 3 / m 3 ;

[0035] Preferably, the first hydroisomerization reaction conditions and the second hydroisomerization reaction conditions are: reaction temperature 280 - 350 °C, reaction pressure 2.0 - 8.0 MPa, volumetric space velocity 0.5 - 5.0 h-1 , with a hydrogen-oil volume ratio of 500 - 1000 Nm 3 / m 3 ;

[0036] Preferably, the reaction temperature of the second hydroisomerization reaction conditions is 5 - 30 °C higher than that of the first hydroisomerization reaction conditions.

[0037] 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.

[0038] In one embodiment of the present invention, the hydroisomerization catalyst further contains a binder, and the binder is alumina and / or silica;

[0039] Based on the total amount of the hydroisomerization catalyst, the content of the binder is 20 - 80% by weight.

[0040] 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.

[0041] 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.

[0042] In the present invention, the content of the alkaline metal oxide is determined by using a Rigaku 3271E X-ray fluorescence spectrometer (XRF) of Rigaku Corporation of 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 the alkaline metal oxide is not higher than 0.001% by weight.

[0043] In one embodiment of the present invention, the preparation method of the hydroisomerization catalyst includes the following steps:

[0044] Step 1: Shaping the dried powder of the ZSM-48 molecular sieve to obtain a shaped carrier;

[0045] 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 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;

[0046] Wherein, 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;

[0047] Step two: subject the shaped carrier to ammonium exchange;

[0048] Step three: introduce an active metal component onto the product obtained in step two to obtain a hydroisomerization catalyst;

[0049] Wherein, the active metal component is Pt and / or Pd.

[0050] In the present invention, the dried powder of the ZSM-48 molecular sieve refers to the dried powder of the ZSM-48 molecular sieve. The drying is a conventional operation in the art, as long as the dried powder of the 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 the 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.

[0051] In the present invention, the test method for the water content is as follows: take a dried powder of the 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 the ZSM-48 molecular sieve can be calculated.

[0052] Water content (% by weight) = (M - M after drying) / M × 100%.

[0053] In the present invention, preferably, the preparation method of the ZSM-48 molecular sieve includes the following steps:

[0054] (1) Provide a mixture containing a silicon source, an alkali source, an aluminum source, a template agent, water, a molecular sieve mother liquor, and crystal seeds;

[0055] (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;

[0056] (3) The mixture obtained from the crystallization reaction in step (2) is subjected to solid-liquid separation to obtain ZSM-48 molecular sieve and molecular sieve mother liquor, and the molecular sieve mother liquor is returned to step (1);

[0057] This method further optionally includes step (4), and step (4) includes: acidifying and depositing the molecular sieve mother liquor, and then performing solid-liquid separation, and the obtained filtrate is returned to step (1);

[0058] The mass percentage of the added seed crystals in step (1) based on the mass of the silicon source is not less than 10%, and the silicon source is calculated as SiO2.

[0059] According to the present invention, the ZSM-48 molecular sieve is prepared by the way of recycling the molecular sieve mother liquor and introducing seed crystals, which is beneficial to the formation of small crystal grains. In the present invention, through the crystallization process at three 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.

[0060] 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 seed crystals, it is beneficial to the formation of small crystal grains.

[0061] In the present invention, the proportion of each raw material 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 in step (1) calculated by molar amount satisfies the following relationship:

[0062] R / SiO2 = 0.01 - 0.4, preferably 0.01 - 0.08;

[0063] M + / SiO2 = 0.01 - 0.4, preferably 0.1 - 0.2;

[0064] Al2O3 / SiO2 = 0 - 0.02, preferably 0.01 - 0.015;

[0065] H2O / SiO2 = 5 - 30, preferably 5 - 20;

[0066] Among them, SiO2 refers to SiO2 in the silicon source, R represents the template agent, and M + represents the base source.

[0067] 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.

[0068] 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) based on 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.

[0069] 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) based on the total mass of the molecular sieve mother liquor and water in step (1) is not more than 50%, more preferably 10 - 30%. In the above preferred case, it helps to form a molecular sieve with small crystal grains and a high specific surface area.

[0070] 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.

[0071] Preferably, the time for the acidification deposition is 0.5 - 4 h.

[0072] In the present invention, the selection range of the silicon source, alkali source, aluminum source, and template agent in step (1) is relatively wide, and the above raw materials are all conventional selections in the art. Generally, the above raw materials should be mixed into a uniform gel by corresponding means, for example, they can be mixed by stirring.

[0073] 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.

[0074] 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.

[0075] According to the present invention, preferably, the aluminum source is selected from at least one of pseudoboehmite, aluminum sulfate, aluminum isopropoxide, and sodium aluminate; more preferably pseudoboehmite.

[0076] 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.

[0077] 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 the aluminum source in the raw materials and the preparation method.

[0078] In the XRD diffraction pattern of the calcined ZSM-48 molecular sieve raw powder synthesized by the existing technical methods at present, the 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, and the diffraction peak at 7° - 8° is relatively weak. The researchers of the present invention found that by adopting a specific synthesis method, the preferred ZSM-48 molecular sieve seed crystal of the present invention can be prepared. In the X-ray diffraction pattern of the calcined ZSM-48 molecular sieve seed crystal, 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 seed crystal, 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 the template agent 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 - 8 h. The ZSM-48 molecular sieve seed crystal prepared in the preparation example of the present invention was calcined at 600 °C for 4 h before characterization.

[0079] In an 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;

[0080] The auxiliary agent is an inorganic acid, preferably nitric acid and / or hydrochloric acid;

[0081] The binder is selected from at least one of alumina, silica, pseudo-boehmite and silica sol, and is preferably pseudo-boehmite.

[0082] 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;

[0083] The calcination conditions include: the calcination temperature is 300-600 °C, and the calcination time is 2-10 h.

[0084] 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;

[0085] 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.

[0086] 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.

[0087] The ammonium salt is selected from at least one of ammonium nitrate, ammonium sulfate, ammonium chloride and ammonium acetate.

[0088] 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 containing a soluble compound of the active metal component, and then drying and calcining to obtain the hydroisomerization catalyst;

[0089] 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;

[0090] The drying temperature is 80-120 °C, and the drying time is 2-6 hours;

[0091] The calcination temperature is 400-500 °C, and the calcination time is 2-6 hours.

[0092] The hydroisomerization catalyst described in the present invention is a reduced 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 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.

[0093] The preferred method for preparing 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.

[0094] In one embodiment of the present invention, the first hydroisomerization reaction effluent and the second hydroisomerization reaction effluent 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 biojet fuel. The obtained biojet fuel is almost entirely composed of saturated alkanes, with stable properties and meeting the requirements of HEFA-SPK in No. 3 jet fuel.

[0095] The characteristics of the present invention are as follows:

[0096] (1) According to the different properties of the oil-based raw materials, the present invention can select a targeted technical solution for the hydrotreating reaction zone. When the sulfur and nitrogen content of the oil-based raw materials is low, a single-molybdenum metal hydrotreating catalyst is selected to obtain more liquid hydrocarbons in terms of yield; when the sulfur and nitrogen content of the oil-based raw materials is high, a multi-metal hydrotreating catalyst is selected to obtain liquid hydrocarbons with lower sulfur and nitrogen impurity content; when the sulfur and nitrogen content of the oil-based raw materials is in the middle, a single-molybdenum metal hydrotreating catalyst and a multi-metal hydrotreating catalyst are selected for staged loading to obtain liquid hydrocarbons with lower sulfur and nitrogen impurity content in the maximum yield.

[0097] (2) The present invention cuts the light and heavy components of the liquid hydrocarbons and enters different hydroisomerization reaction zones. By adopting a zoning control method, the depth of hydroisomerization and cracking of different carbon numbers can be effectively controlled, the occurrence of deep cracking reactions can be reduced, and the yield of biojet fuel can be increased.

[0098] (3) The preferred hydroisomerization catalyst of the present invention has higher catalytic activity in the hydroisomerization reaction of liquid hydrocarbons and can significantly increase the yield of biojet fuel. BRIEF DESCRIPTION OF THE DRAWINGS

[0099] Figure 1 A process schematic diagram of one embodiment of the hydrogenation method for producing biojet fuel from oil-based raw materials provided by the present invention;

[0100] Figure 2 It is the X-ray diffraction pattern of the seed crystal A1 obtained in Preparation Example 1-1 after calcination;

[0101] Figure 3 It is the X-ray diffraction pattern of the seed crystal A3 obtained in Preparation Example 1-3 after calcination;

[0102] Figure 4 It is the SEM image of the ZSM-48 molecular sieve obtained in Preparation Example 2-1. Detailed implementation manners

[0103] The present invention will be further described below in conjunction with the accompanying drawings, but the present invention is not limited thereby.

[0104] Figure 1 It is a process schematic diagram of one implementation manner of the hydrogenation method for producing bio-jet fuel from oil-based raw materials provided by the present invention. As Figure 1 shown, the oil-based raw material 1, fresh hydrogen 2 and recycled hydrogen 25 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 under the hydrotreating reaction conditions in contact with the hydrotreating catalyst I and / or hydrotreating catalyst II 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 10 is recycled after being pressurized by the recycle hydrogen compressor 11 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 fractionating tower 12 together as liquid hydrocarbons for fractionation to obtain the light liquid hydrocarbon fraction 13 and the heavy liquid hydrocarbon fraction 14.

[0105] The obtained light liquid hydrocarbon fraction 13, fresh hydrogen 26 and recycled hydrogen 19 enter the hydroisomerization reactor 15 in the first hydroisomerization reaction zone and react under the first hydroisomerization reaction conditions in contact with the hydroisomerization catalyst to obtain the first hydroisomerization reaction effluent. The obtained heavy liquid hydrocarbon 14 and fresh hydrogen 27 enter the hydroisomerization reactor 16 in the second hydroisomerization reaction zone and react under the second hydroisomerization reaction conditions in contact with the hydroisomerization catalyst to obtain the second hydroisomerization reaction effluent.

[0106] The first hydroisomerization reaction effluent and the second hydroisomerization reaction effluent 17 enter the high-pressure separator 18 for gas-liquid separation. The obtained gas-phase stream 19 is recycled back to the hydroisomerization reactor 15. The obtained liquid-phase stream 20 enters the fractionating tower 21 for fractionation to obtain bio-naphtha 22, bio-jet fuel 23 and biodiesel 24.

[0107] The following examples will further illustrate the present invention, but should not be construed as limiting the present invention.

[0108] The hydroisomerization catalyst used in the examples and comparative examples was prepared by the following process.

[0109] In the following Preparation Examples and Comparative Preparation Examples, the XRD characterization of the samples was carried out using a Bruker D5005 diffractometer, with CuKα radiation (λ = 0.154 nm), tube voltage of 40 kV, tube current of 30 mA, scanning range of 5° - 35°, step size of 0.013°, and 1 step per second. The morphology and size of the samples were characterized using an S-4800 scanning electron microscope (SEM) produced by Hitachi, with an acceleration voltage of 20 kV.

[0110] The composition of the samples, including the content of alkaline metal oxides, was determined using a Rigaku 3271E X-ray fluorescence spectrometer (XRF). The sample preparation method was the tablet pressing method, and the measurement conditions were an end-window rhodium target, tube voltage of 50 kV, and tube current of 50 mA.

[0111] The mesoporous structure parameters of the product, such as specific surface area and pore volume, were measured using nitrogen adsorption and the BET method.

[0112] The following Preparation Examples are used to illustrate the preparation of seeds.

[0113] Preparation Example 1-1

[0114] Aluminum sulfate, hexamethylenediamine hydroxide (HMOH), sodium hydroxide, and deionized water were mixed in a certain ratio, and after stirring for 30 min, 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 the crystallization was completed, the obtained product was filtered and dried to obtain 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.

[0115] Preparation Example 1-2

[0116] 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 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 at a stirring speed of 350 rpm; 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, the product obtained by filtration and drying was seed crystal 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.

[0117] Preparation Example 1 - 3

[0118] Sodium aluminate, hexamethylenediamine chloride (HMCl), sodium hydroxide, and deionized water were mixed in a certain proportion and stirred for 30 min, then 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 at a stirring speed of 350 rpm; crystallized at 170 °C for 60 h. After crystallization, filtration and drying were carried out, and the product obtained was seed crystal A3. After seed crystal A3 was calcined at 600 °C for 4 h, XRD showed 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.

[0119] The following preparation examples are used to illustrate the preparation of ZSM - 48 molecular sieve.

[0120] Preparation Example 2 - 1

[0121] (1) Aluminum sulfate, hexamethylenediamine chloride (HMCl), sodium hydroxide, and deionized water containing molecular sieve mother liquor were mixed in a certain proportion and stirred for 30 min, then silica sol was added. The molar ratios of various substances were 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 ZSM - 48 seed crystal A1 with 25% of the added SiO2 mass was added;

[0122] (2) The above mixture was transferred to a crystallization kettle and stirred at room temperature for 6 h, crystallized at 80 °C for 24 h, and crystallized at 170 °C for 48 h;

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

[0124] 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.

[0125] Preparation Example 2-2

[0126] (1) Mix sodium aluminate, hexamethylenediamine chloride (HMCl), sodium hydroxide, and deionized water containing the molecular sieve mother liquor in a certain ratio, stir for 30 min, 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 added mass of the molecular sieve mother liquor accounts for 20% of the total mass of the molecular sieve mother liquor and water described in step (1), and add ZSM-48 seed crystal A2 accounting for 15% of the added SiO2 mass;

[0127] (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;

[0128] (3) After crystallization, filter, and dry at 120 °C for 6 h 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%;

[0129] The XRF analysis results of the silicon-aluminum ratio of Z-2 and data such as specific surface area are shown in Table 1, and its morphology is ellipsoidal, the major axis of the particles is 300 - 600 nm, and the ratio of the major axis to the minor axis is about 1.1 - 1.4:1.

[0130] Comparative Preparation Example 1

[0131] (1) Mix aluminum sulfate, hexamethylenediamine chloride (HMCl), sodium hydroxide, and deionized water containing the molecular sieve mother liquor in a certain ratio, stir for 30 min, 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 ZSM-48 seed crystal A3 accounting for 25% of the SiO2 mass. The added mass of the molecular sieve mother liquor accounts for 20% of the total mass of the molecular sieve mother liquor and water described in step (1);

[0132] (2) Transfer the above mixture into a crystallization kettle, stir it at room temperature for 6 h, crystallize it at 80 °C for 24 h, and crystallize it at 170 °C for 48 h;

[0133] (3) After crystallization, filter it, dry it 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%;

[0134] The XRF analysis results, specific surface area and other data of DZ-1 are shown in Table 1. Its morphology is rod-shaped, and the ratio of the long diameter to the short diameter is about 7:1.

[0135] Table 1

[0136]

[0137] The following preparation examples are used to illustrate the preparation of the hydroisomerization catalyst.

[0138] Preparation Example 3-1

[0139] Mix 70 g of the Z-1 sample from Preparation Example 2-1 with 40 g of pseudoboehmite with a dry basis and 2 g of nitric acid solution, form it, and calcine it at 580 °C for 3 h. Then put the carrier strip into a 0.5 M ammonium chloride solution and exchange it at 90 °C for 2 h. Take out the carrier strip, dry it, and measure the sodium oxide content. The results are shown in Table 2.

[0140] Pour dichlorotetraammineplatinum (with a Pt mass fraction of 57.3%) into 100 g of deionized water and stir until uniform. Pour 100 g of the carrier into the above solution and impregnate it at room temperature for 4 hours. Subsequently, dry the above catalyst precursor at 120 °C for 4 hours. Then calcine it in a state of passing an air stream. The calcination temperature is 450 °C and the time is 4 hours. The obtained semi-finished catalyst is put into a hydrogen atmosphere again and reduced at 400 °C for 4 hours to obtain the catalyst. The obtained hydroisomerization catalyst is named CAT-1. Calculated by elements, the Pt loading in the catalyst is 0.5 wt%.

[0141] Preparation Example 3-2

[0142] According to the method and the same catalyst composition in Preparation Example 3-1, the difference is that Z-2 from Preparation Example 2-2 is used to replace Z-1. After ammonium exchange, take out the carrier strip, dry it, and measure the sodium oxide content. The results are shown in Table 2. The obtained hydroisomerization catalyst is named CAT-2.

[0143] Comparative Preparation Example 3-1

[0144] 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 carrier 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.

[0145] Comparative Preparation Example 3-2

[0146] 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 pellets. The sodium oxide content was measured. The results are shown in Table 2. The obtained hydroisomerization catalyst was named DCAT-2.

[0147] Table 2

[0148]

[0149]

[0150] Example 1

[0151] In this example, used cooking waste oil A was used as the oil raw material, and the main properties of used cooking waste oil A are shown in Table 3.

[0152] 100 mL of hydrotreating catalyst II was loaded in the hydrotreating reaction zone. Its carrier was alumina. Based on the hydrotreating catalyst II and calculated as oxides, the nickel content was 4.2 wt% and the molybdenum content was 26.5 wt%.

[0153] 20 mL of hydroisomerization catalyst CAT-1 was loaded in the first hydroisomerization reaction zone.

[0154] 80 mL of hydroisomerization catalyst CAT-2 was loaded in the second hydroisomerization reaction zone.

[0155] Used cooking waste oil A and hydrogen entered the hydrotreating reaction zone together. Sulfurizing agent SZ was added to used cooking waste oil A 54 , and the concentration of the sulfurizing agent was 0.3 wt%. Under the hydrotreating reaction conditions, it was contacted with the sulfided hydrotreating catalyst II for reaction to obtain a hydrotreating reaction effluent. The hydrotreating reaction conditions were: reaction pressure 6.4 MPa, reaction temperature 295 °C, volume space velocity 1.0 h -1 and hydrogen-oil volume ratio 1000. The obtained hydrotreating reaction effluent was subjected to gas-liquid separation to obtain a liquid hydrocarbon, water and gas stream. The conversion rate of used cooking waste oil A was 100%. The final boiling point temperature of the obtained liquid hydrocarbon was less than 350 °C, the liquid hydrocarbon yield was 82 wt%, in the obtained liquid hydrocarbon, the content of even-carbon-chain alkanes was 57 wt%, the sulfur content was 3 μg / g, and the nitrogen content was 1 μg / g.

[0156] The liquid hydrocarbon is cut to obtain a light fraction of the liquid hydrocarbon and a heavy fraction of the liquid hydrocarbon, and the cutting point is 295 °C.

[0157] The obtained light fraction of the 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. The first hydroisomerization reaction conditions are as follows: reaction temperature 330 °C, reaction pressure 6.4 MPa, volume hourly space velocity 1.0 h -1 and hydrogen-to-oil volume ratio 600.

[0158] The obtained heavy fraction of the liquid hydrocarbon enters the second hydroisomerization reaction zone and reacts with a hydroisomerization catalyst under the second hydroisomerization reaction conditions to obtain a second hydroisomerization reaction effluent. The second hydroisomerization reaction conditions are as follows: reaction temperature 335 °C, reaction pressure 6.4 MPa, volume hourly space velocity 1.0 h -1 and hydrogen-to-oil volume ratio 600.

[0159] The first hydroisomerization reaction effluent and the second hydroisomerization reaction effluent are subjected to gas-liquid separation and liquid-phase fractionation to obtain biojet fuel.

[0160] The total liquid product yield of the first and second hydroisomerization reaction zones is 98 wt%, the yield of biojet fuel (boiling range 140 - 300 °C) is 77 wt%, and the freezing point of the biojet fuel is -48 °C.

[0161] Based on the used waste cooking oil A, the yield of biojet fuel is 63 wt%.

[0162] Example 2

[0163] In this example, waste cooking oil B is used as the oil raw material, and the main properties of waste cooking oil B are shown in Table 3.

[0164] The hydrotreating reaction zone is filled with 80 mL of hydrotreating catalyst I and 20 mL of hydrotreating catalyst II in sequence. The carrier of hydrotreating catalyst I is alumina, and based on oxides and based on hydrotreating catalyst I, the content of molybdenum is 15 wt%; the carrier of hydrotreating catalyst II is alumina, and based on oxides and based on hydrotreating catalyst II, the content of nickel is 4.0 wt% and the content of tungsten is 28 wt%.

[0165] The first hydroisomerization reaction zone is filled with 50 mL of hydroisomerization catalyst CAT-1.

[0166] The second hydroisomerization reaction zone is filled with 50 mL of hydroisomerization catalyst CAT-2.

[0167] Catering waste oil B and hydrogen enter the hydrotreating reaction zone together. Dimethyl disulfide, a sulfurizing agent, is added to catering waste oil B, and the concentration of the sulfurizing agent is 0.25 wt%. Under hydrotreating reaction conditions, it contacts with the sulfided hydrotreating catalyst I and hydrotreating catalyst II for reaction to obtain a hydrotreating reaction effluent. The hydrotreating reaction conditions are as follows: reaction pressure 6.4 MPa, reaction temperature 310 °C, volume hourly space velocity 1.0 h -1 and a hydrogen-to-oil volume ratio of 1000. The obtained hydrotreating reaction effluent is subjected to gas-liquid separation to obtain liquid hydrocarbons, water, and a gas stream. The conversion rate of catering waste oil B is 100%, the final boiling point temperature of the obtained liquid hydrocarbons is less than 350 °C, the liquid hydrocarbon yield is 84 wt%, in the obtained liquid hydrocarbons, the content of even-carbon-chain alkanes is 94 wt%, the sulfur content is 5 μg / g, and the nitrogen content is 1 μg / g.

[0168] The liquid hydrocarbons are cut to obtain light liquid hydrocarbon components and heavy liquid hydrocarbon components, and the cutting point is 305 °C.

[0169] The obtained light liquid hydrocarbon components enter the first hydroisomerization reaction zone and, under the first hydroisomerization reaction conditions, contact with a hydroisomerization catalyst for reaction to obtain a first hydroisomerization reaction effluent. The first hydroisomerization reaction conditions are: reaction temperature 330 °C, reaction pressure 6.4 MPa, volume hourly space velocity 1.0 h -1 and a hydrogen-to-oil volume ratio of 600.

[0170] The obtained heavy liquid hydrocarbon components enter the second hydroisomerization reaction zone and, under the second hydroisomerization reaction conditions, contact with a hydroisomerization catalyst for reaction to obtain a second hydroisomerization reaction effluent. The second hydroisomerization reaction conditions are: reaction temperature 335 °C, reaction pressure 6.4 MPa, volume hourly space velocity 1.0 h -1 and a hydrogen-to-oil volume ratio of 600.

[0171] The first hydroisomerization reaction effluent and the second hydroisomerization reaction effluent are subjected to gas-liquid separation and liquid-phase fractionation to obtain biojet fuel.

[0172] The total liquid product yield in the first and second hydroisomerization reaction zones is 97 wt%, the yield of biojet fuel (boiling range 140 - 300 °C) is 76 wt%, and the freezing point of the biojet fuel is -51 °C.

[0173] Based on catering waste oil B, the yield of biojet fuel is 64 wt%.

[0174] Example 3

[0175] In this example, catering waste oil C is used as the oil-based raw material, and the main properties of catering waste oil C are shown in Table 3.

[0176] The hydrotreating reaction zone is filled with 100 mL of hydrotreating catalyst I. The carrier of hydrotreating catalyst I is alumina. Based on the oxide and taking hydrotreating catalyst I as the reference, the content of molybdenum is 15 wt%.

[0177] The first hydroisomerization reaction zone is filled with 30 mL of hydroisomerization catalyst CAT-1.

[0178] The second hydroisomerization reaction zone is filled with 70 mL of hydroisomerization catalyst CAT-2.

[0179] Catering waste oil C and hydrogen enter the hydrotreating reaction zone together. Dimethyl disulfide as a sulfiding agent is added to catering waste oil C, and the concentration of the sulfiding agent is 0.2 wt%. Under the hydrotreating reaction conditions, it contacts with the sulfided hydrotreating catalyst I for reaction to obtain the hydrotreating reaction effluent. The hydrotreating reaction conditions are: reaction pressure 6.4 MPa, reaction temperature 310 °C, volume hourly 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 catering waste oil C is 100%. The final boiling point temperature of the obtained liquid hydrocarbons is less than 350 °C, the liquid hydrocarbon yield is 85 wt%, in the obtained liquid hydrocarbons, the content of even-carbon-chain alkanes is 96 wt%, the sulfur content is 5 μg / g, and the nitrogen content is 1 μg / g.

[0180] The liquid hydrocarbons are cut to obtain light liquid hydrocarbon components and heavy liquid hydrocarbon components, and the cutting point is 300 °C.

[0181] The obtained light liquid hydrocarbon components enter the first hydroisomerization reaction zone. Under the first hydroisomerization reaction conditions, they contact with the hydroisomerization catalyst for reaction to obtain the first hydroisomerization reaction effluent. The first hydroisomerization reaction conditions are: reaction temperature 330 °C, reaction pressure 6.4 MPa, volume hourly space velocity 1.0 h -1 and hydrogen-oil volume ratio 600,

[0182] The obtained heavy liquid hydrocarbon components enter the second hydroisomerization reaction zone. Under the second hydroisomerization reaction conditions, they contact with the hydroisomerization catalyst for reaction to obtain the second hydroisomerization reaction effluent. The second hydroisomerization reaction conditions are: reaction temperature 335 °C, reaction pressure 6.4 MPa, volume hourly space velocity 1.0 h -1 and hydrogen-oil volume ratio 600,

[0183] The first hydroisomerization reaction effluent and the second hydroisomerization reaction effluent are subjected to gas-liquid separation and liquid-phase fractionation to obtain biojet fuel.

[0184] The total liquid product yield of the first and second hydroisomerization reaction zones is 97 wt%, the yield of bio-jet fuel (boiling range 140 - 300 °C) is 77 wt%, and the freezing point of the bio-jet fuel is -49 °C.

[0185] Based on waste cooking oil C, the yield of bio-jet fuel is 65 wt%.

[0186] Comparative Example 1

[0187] This comparative example uses the same raw materials, hydrotreating catalyst, and hydrotreating reaction conditions as in Example 1. The effluent from the hydrotreating reaction is subjected to gas-liquid separation to obtain liquid hydrocarbons, water, and a gas stream.

[0188] The obtained liquid hydrocarbons are not fractionated and all enter the hydroisomerization reactor, which is filled with 100 mL of hydroisomerization catalyst CAT-1. At a reaction pressure of 6.4 MPa, a reaction temperature of 330 °C, a volume hourly space velocity of 1.0 h -1 and a hydrogen-to-oil volume ratio of 600, the liquid hydrocarbons undergo a hydroisomerization reaction. After the effluent from the hydroisomerization reaction is subjected to gas-liquid separation and liquid-phase fractionation, bio-jet fuel is obtained.

[0189] The liquid product yield of the hydroisomerization reaction is 98 wt%, the yield of bio-jet fuel (boiling range 140 - 300 °C) is 57 wt%, and the freezing point of the bio-jet fuel is -40.7 °C.

[0190] Based on waste cooking oil A, the yield of bio-jet fuel is 46.7 wt%.

[0191] Comparative Example 2

[0192] The first hydroisomerization reaction zone is filled with 20 mL of hydroisomerization catalyst DCAT-1.

[0193] The second hydroisomerization reaction zone is filled with 80 mL of hydroisomerization catalyst DCAT-2.

[0194] This comparative example uses the same raw materials, hydrotreating catalyst, and hydrotreating reaction conditions as in Example 1. The effluent from the hydrotreating reaction is subjected to gas-liquid separation to obtain liquid hydrocarbons, water, and a gas stream.

[0195] The liquid hydrocarbons are cut to obtain light liquid hydrocarbon components and heavy liquid hydrocarbon components, and the cutting point is 295 °C.

[0196] The obtained light liquid hydrocarbon components enter the first hydroisomerization reaction zone and, under the first hydroisomerization reaction conditions, contact the hydroisomerization catalyst to react, obtaining the effluent from the first hydroisomerization reaction. The first hydroisomerization reaction conditions: reaction temperature 333 °C, reaction pressure 6.4 MPa, volume hourly space velocity 1.0 h -1and a hydrogen-to-oil volume ratio of 600,

[0197] The heavy fraction of the obtained liquid hydrocarbons enters the second hydroisomerization reaction zone, where it reacts with a hydroisomerization catalyst under the second hydroisomerization reaction conditions to obtain a second hydroisomerization reaction effluent. The second hydroisomerization reaction conditions are: a reaction temperature of 333 °C, a reaction pressure of 6.4 MPa, a volume hourly space velocity of 1.0 h -1 and a hydrogen-to-oil volume ratio of 600,

[0198] After the first hydroisomerization reaction effluent and the second hydroisomerization reaction effluent are subjected to gas-liquid separation and liquid-phase fractionation, biojet fuel is obtained.

[0199] The total liquid product yield of the first and second hydroisomerization reaction zones is 97 wt%, the yield of biojet fuel (boiling range 140 - 300 °C) is 52 wt%, and the freezing point of the biojet fuel is -51 °C.

[0200] Based on the waste cooking oil A, the yield of biojet fuel is 42.6 wt%.

[0201] It can be seen from the examples that by using the method of the present invention, a highly active hydroisomerization catalyst and a zoning control method in the hydroisomerization reaction zone effectively improve the yield of biojet fuel.

[0202] Table 3

[0203] Item Food waste oil A Food waste oil B Food waste oil C <![CDATA[Density (20 °C), g / cm 3 > 919.5 916.2 918.9 Sulfur content, μg / g 40 25 28 Nitrogen content, μg / g 151 77 49 Oxygen content, wt% 10.69 10.34 11 Total acid value, mgKOH / g 19 7.8 3.2

Claims

1. A hydrogenation method for producing biojet fuel from oil and fat raw materials, comprising: (1) The oil and fat raw materials and hydrogen enter the hydrotreating reaction zone together, and under hydrotreating reaction conditions, react with hydrotreating catalyst I and / or hydrotreating catalyst II to obtain a hydrotreating reaction effluent. The hydrotreating catalyst I is a single molybdenum catalyst, and the hydrotreating catalyst II is a multi-metal catalyst. (2) The hydrotreating reaction effluent obtained in step (1) is subjected to gas-liquid separation to obtain a liquid hydrocarbon, water, and a gas stream. The liquid hydrocarbon is cut to obtain a light liquid hydrocarbon fraction and a heavy liquid hydrocarbon fraction, and the cutting point is 290-310 °C. (3) The light liquid hydrocarbon fraction obtained in step (2) 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. (4) The heavy liquid hydrocarbon fraction obtained in step (2) enters the second hydroisomerization reaction zone and reacts with a hydroisomerization catalyst under the second hydroisomerization reaction conditions to obtain a second hydroisomerization reaction effluent. The first hydroisomerization reaction effluent and the second hydroisomerization reaction effluent are subjected to gas-liquid separation and liquid-phase fractionation to obtain biojet fuel. The hydroisomerization catalyst described in step (3) and step (4) 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; 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 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. 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.

2. The method according to claim 1, characterized in that, The oil and fat raw materials are animal and vegetable oils and fats and / or waste cooking oil. When the sulfur content and nitrogen content in the oil and fat raw materials are both <50 μg / g, the hydrotreating reaction zone is filled with hydrotreating catalyst I. When the sulfur content and nitrogen content in the oil and fat raw materials are both between 50-150 μg / g, the hydrotreating reaction zone is filled with hydrotreating catalyst I and hydrotreating catalyst II, and the filling volume ratio of hydrotreating catalyst I and hydrotreating catalyst II is 1:9-9:

1. When the sulfur content and nitrogen content in the oil and fat raw materials are both >150 μg / g, the hydrotreating reaction zone is filled with hydrotreating catalyst II.

3. The method according to claim 1 or 2, wherein The carrier of the hydrotreating catalyst I is selected from one or more of alumina, silica, titanium oxide, and zirconium oxide. The active metal of the hydrotreating catalyst I is molybdenum. Based on the oxide and based on the hydrotreating catalyst I, the content of molybdenum is 10% by weight to less than 17% by weight.

4. The method according to claim 1 or 2, characterized in that The carrier of the hydrotreating catalyst II is selected from one or more of alumina, silica, titanium oxide, and zirconium oxide. The active metals of the hydrotreating catalyst II are two or more metals selected from cobalt, nickel, molybdenum, and tungsten. Based on the oxide and based on the hydrotreating catalyst II, 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.

5. The method according to claim 1, characterized in that, 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 .

6. The method according to claim 1, wherein 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 successively enters a stripping column for stripping and a dehydration column for dehydration to remove dissolved hydrogen sulfide, ammonia, and water, thereby obtaining a liquid hydrocarbon.

7. The method according to claim 1, characterized in that, 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 - 10.0 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 ; Preferably, the first hydroisomerization reaction conditions and the second hydroisomerization reaction conditions are as follows: reaction temperature 280 - 350 °C, reaction pressure 2.0 - 8.0 MPa, volumetric space velocity 0.5 - 5.0 h -1 , hydrogen-to-oil volume ratio 500 - 1000 Nm 3 / m 3 ; Preferably, the reaction temperature of the second hydroisomerization reaction conditions is 5 - 30 °C higher than that of the first hydroisomerization reaction conditions.

8. The method according to claim 1, wherein In the hydroisomerization catalyst, based on the total amount of the hydroisomerization catalyst, the content of molecular sieve on a dry basis is 30 - 70 wt%, and based on elements, the content of the active metal component is 0.2 - 10 wt%.

9. The method according to claim 1 or 8, characterized in that, The hydroisomerization catalyst also 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 wt%.

10. The method according to claim 1, wherein The aspect ratio of the ZSM-48 molecular sieve is 1-2:1; the crystal grain 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 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 wt%; Step two: Subjecting the shaped carrier to ammonium exchange; Step three: Introducing an active metal component onto the product obtained in step two 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 one 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, pseudo-boehmite, and silica sol, preferably pseudo-boehmite.

13. The method according to claim 12, characterized in that, 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; The conditions of 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 two includes: contacting the shaped carrier with an aqueous solution of an ammonium salt; The conditions of 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, characterized in that, The method for introducing the active metal component in step three includes: impregnating the product in step two 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 of the drying is 80 - 120 °C, and the time of the drying is 2 - 6 hours; The temperature of the calcination is 400 - 500 °C, and the time of the calcination is 2 - 6 hours.

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