Method for producing biodiesel fraction from grease raw materials

Abstract

The invention relates to a method for producing a biodiesel fraction from a grease raw material, which comprises the following steps of: contacting the grease raw material with a hydrotreating catalyst I and / or a hydrotreating catalyst II in a hydrotreating reaction zone to react, separating the hydrotreating reaction effluent, feeding the obtained liquid hydrocarbon into a hydroisomerization reaction zone to contact with a hydroisomerization catalyst to react, and separating an effluent of the hydroisomerization reaction to obtain a biodiesel fraction. According to different raw materials, the technical scheme of the hydrotreating reaction zone is flexibly adjusted, and the high-quality biodiesel fraction can be prepared with high yield.

Description

Technical Field

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

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

[0003] Biodiesel has gradually attracted people's attention mainly for the following reasons: 1. Biodiesel is a renewable energy source; 2. The carbon-containing characteristics of biodiesel are close to those of existing fuels; 3. The carbon dioxide absorbed by the precursors of biodiesel can reduce the net emission of greenhouse gases; 4. The distribution of bioenergy is more uniform than that of fossil energy.

[0004] Vegetable oil is the most easily available biodiesel, mainly composed of triglycerides and a small amount of free fatty acids. The use of vegetable oil in diesel engines can be traced back to 1900, when Rudolf Diesel demonstrated the operating ability of peanut oil in diesel engines. During World War II, palm oil and peanut oil were used as fuels for military vehicles in Africa. After the war, technological developments led to petroleum-derived fuels becoming almost the sole feedstock, especially with the significant improvements in diesel engine injectors and control systems, resulting in a very limited source of diesel engine feedstock. At the same time, pure vegetable oil has a high viscosity, poor stability, and high cost, which limits its direct application as a transportation fuel.

[0005] 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 to convert the triglycerides forming vegetable oil into the corresponding fatty acid alkyl esters, usually fatty acid methyl esters. However, the low-temperature fluidity of fatty acid methyl esters limits their use in low-temperature environments. The low-temperature fluidity of fatty acid methyl esters is determined by the chain characteristics of their fatty acids. The presence of carbon-carbon double bonds can improve low-temperature fluidity but reduces the stability of fatty acid methyl esters. Since the presence of oxygen in fatty acid methyl esters leads to higher NOx emissions compared to traditional diesel fuels.

[0006] Diesel components can be produced from oils and fats through hydrogenation technology, but the resulting products are normal paraffins with a high freezing point and poor low-temperature fluidity. To improve the low-temperature flow properties of the hydrogenation products, the usual method is to subject the products to isomerization reactions. A raw material selected from vegetable oils, animal oils, or fish oils is subjected to a hydrodeoxygenation step, followed by a hydroisomerization step.

[0007] In the prior art, the preparation of hydroisomerization catalysts usually involves an ammonium exchange after crystallization followed by an extrusion molding method. However, the alkali metal content in the resulting 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 method for producing biodiesel fractions from oil and fat raw materials on the basis of the prior art to solve the problem of low yield of biodiesel fractions in the prior art.

[0009] The method for producing biodiesel fractions from oil and fat raw materials provided by the present invention includes:

[0010] (1) The oil and fat raw material and hydrogen enter the hydrotreating reaction zone together and react under hydrotreating reaction conditions in contact 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.

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

[0012] (3) The liquid hydrocarbon obtained in step (2) enters the hydroisomerization reaction zone and reacts under hydroisomerization reaction conditions in contact with a hydroisomerization catalyst. The hydroisomerization reaction effluent obtained is separated to obtain biodiesel fractions.

[0013] The hydroisomerization catalyst includes a carrier and an active metal component supported on the carrier. The carrier contains ZSM-48 zeolite. The molar ratio of silica to alumina in the ZSM-48 zeolite is not less than 40. The specific surface area of the ZSM-48 zeolite is not less than 200 m 2 / g. The crystal grains of the ZSM-48 zeolite are ellipsoidal, with a major axis not exceeding 700 nm and a major axis to minor axis ratio of 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 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 the transesterification method from vegetable oils and / or animal fats. The waste cooking oil is the oil waste that is not suitable for further consumption generated in the processing of animal and vegetable oils and edible consumption. It includes fatty acids, acidified oil, etc. generated in the production of edible oil from oilseeds; various waste cooking oils such as frying waste oil, kitchen waste oil, and swill oil generated from the use of edible oil by households, hotels, the catering industry, and food production enterprises; animal fats by-produced in the production and processing of meat, and edible oil beyond the shelf life, etc.

[0018] According to the different properties of the oil and fat raw materials, the present invention can select a targeted technical solution for the hydrotreating reaction zone.

[0019] 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.

[0020] In one embodiment of the present invention, 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 to 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.

[0021] In one embodiment of the present invention, 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. In the obtained liquid hydrocarbon, the content of even-carbon-chain alkanes is not less than 30% by weight.

[0022] In one embodiment of the present invention, the carrier of hydrotreating catalyst I is selected from one or more of alumina, silica, titanium oxide, and zirconium oxide, and the active metal of hydrotreating catalyst I is molybdenum. Based on oxides and based on hydrotreating catalyst I, the content of molybdenum is 10% by weight to less than 17% by weight.

[0023] 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 oxides 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.

[0024] In one embodiment of the present invention, the hydrotreating reaction conditions are: reaction temperature 250-450 °C, reaction pressure 3.0-10.0 MPa, volumetric space velocity 0.1-10.0 h -1 , hydrogen-oil volume ratio 300-2000 Nm 3 / m 3 ;

[0025] Preferably, the hydrotreating reaction conditions are: reaction temperature 300-400 °C, reaction pressure 4.0-8.0 MPa, volumetric space velocity 0.5-5.0 h -1 , hydrogen-oil volume ratio 500-1500 Nm 3 / m 3 .

[0026] 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.

[0027] 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 the method of recycle oil, or both methods can be used simultaneously.

[0028] 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, etc.

[0029] 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 successively 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.

[0030] The gas stream can be directly recycled or passed through a hydrogen purification unit to obtain a hydrogen-rich gas, and the obtained hydrogen-rich gas is recycled. The hydrogen purification unit can use conventional pressure swing adsorption technology or membrane separation technology.

[0031] 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.

[0032] In step (3) of the present invention, the obtained liquid hydrocarbon enters the hydroisomerization reaction zone and reacts with a hydroisomerization catalyst under hydroisomerization reaction conditions. In one embodiment of the present invention, the hydroisomerization reaction conditions are: reaction temperature 200 - 500 °C, reaction pressure 1.0 - 10.0 MPa, volume space velocity 0.1 - 10.0 h -1 and the hydrogen-oil volume ratio is 200 - 1500 Nm 3 / m 3 ;

[0033] Preferably, the hydroisomerization reaction conditions are: reaction temperature 280 - 350 °C, reaction pressure 2.0 - 8.0 MPa, volume space velocity 0.5 - 5.0 h -1 and the hydrogen-oil volume ratio is 500 - 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 based on 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 ratio of major axis to minor axis, a high silica-alumina ratio, and a large specific surface area. The content of alkaline metals in the carrier is extremely low, and the obtained hydroisomerization catalyst has higher catalytic activity in the hydroisomerization reaction of liquid hydrocarbons.

[0039] 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.

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

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

[0042] The molar ratio of silicon oxide to aluminum oxide 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 ratio of major axis to minor axis 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% by weight;

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

[0048] In the present invention, the test method for water content is as follows: Take the dried powder of ZSM-48 molecular sieve with a mass of M and place it in an oven, dry it at 105-110°C for about 6-8 hours until the sample weight no longer changes. Weigh the dried sample, denoted as M after drying, and the water content of the dried powder of ZSM-48 molecular sieve can be calculated.

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

[0050] In the present invention, preferably, the preparation method of 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 hours, reacting at 50°C - 80°C for 1 - 34 hours, and then reacting at 80°C - 180°C for 1 - 70 hours;

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

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

[0057] In the present invention, those skilled in the art can understand that the above step (3) or steps (3) and (4) can be arbitrarily selected to obtain the molecular sieve mother liquor. When the method provided by the present invention includes step (4), those skilled in the art can understand that the filtrate provides at least part of the molecular sieve mother liquor described in step (1). By adopting the above preferred preparation method, through the way of recycling the molecular sieve mother liquor and introducing seeds, it is beneficial to the formation of small crystal grains.

[0058] In the present invention, the proportions of the raw materials in step (1) can be adjusted according to actual needs. In order to improve the performance of the molecular sieve in the ZSM-48 molecular sieve precursor, and thus further improve the catalytic performance of the catalyst, preferably, the composition of each component in the mixture described in step (1) calculated by molar amount satisfies the following relationship:

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

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

[0066] According to the present invention, preferably, in the mixture of step (1), the amount of the molecular sieve mother liquor is less than that of water. Further preferably, the mass percentage of the added molecular sieve mother liquor in step (1) in the total 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 molecular sieves with small crystal grains and 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 of the acidification deposition is 0.5 - 4 h.

[0069] In the present invention, for the selection of the silicon source, alkali source, aluminum source, and template agent in step (1), the range 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.

[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 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 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 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 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 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 existing technical methods at present, the peak positions of the diffraction peaks generally occur at 2θ angles of 7.5°, 21.2°, 22.8°, and 31.3°. Among them, the diffraction peak at 21°-22° is the highest, while the diffraction peak at 7°-8° has a relatively weak intensity. The researchers of the present invention found that by 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 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. The ZSM-48 molecular sieve seeds prepared in the preparation examples of the present invention were 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, pseudo-boehmite, and silica sol, preferably pseudo-boehmite.

[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 containing a soluble compound of 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 with good isomer 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, simple operation. Based on the ZSM - 48 molecular sieve with a specific structure, by the method of shaping first and then ammonium exchange, the post - treatment difficulty is low, and at the same time, the alkali metal content in the catalyst is extremely low. 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 column for fractionation to obtain a biocrude naphtha fraction and a biodiesel fraction. The obtained biodiesel fraction is sulfur-free, has a low freezing point and a high cetane number, can be used as a diesel product, can also be mixed with fossil-based diesel, and can also be used as an additive to increase the cetane number of diesel.

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

[0093] (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 a higher yield of liquid hydrocarbons; 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 a 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 packing to obtain liquid hydrocarbons with a lower sulfur and nitrogen impurity content in the maximum yield.

[0094] (2) 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 the biodiesel fraction. BRIEF DESCRIPTION OF THE DRAWINGS

[0095] Figure 1 A process flow schematic diagram of one embodiment of the method for producing a biodiesel fraction from oil-based raw materials provided by the present invention;

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

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

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

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

[0100] Figure 1 is a process flow schematic diagram of one embodiment of the method for producing a biodiesel fraction from oil-based raw materials provided by the present invention. As Figure 1As shown, the oil raw material 1, fresh hydrogen 2 and recycled hydrogen 21 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 hydrotreating reaction conditions in contact with the hydrotreating catalyst I and / or the hydrotreating catalyst II to obtain a 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 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 hydroisomerization reaction zone together as liquid hydrocarbons. The water 9 separated from the cold high-pressure separator 6 is discharged from the device. The separated gas-phase stream 12 is processed and then recycled after being pressurized by the recycle hydrogen compressor 13.

[0101] The liquid hydrocarbons, fresh hydrogen 10 and recycled hydrogen 20 enter the fixed-bed hydroisomerization reactor 11 in the hydroisomerization reaction zone and react under hydroisomerization reaction conditions in contact with the hydroisomerization catalyst to obtain a hydroisomerization reaction effluent. The obtained hydroisomerization reaction effluent 14 enters the high-pressure separator 15 for gas-liquid separation. The obtained gas-phase stream is directly recycled back to the hydroisomerization reactor 11. The obtained liquid-phase stream 16 enters the fractionating column 17 for fractionation to obtain a bio-naphtha fraction 18 and a biodiesel fraction 19.

[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 an S-4800 type scanning electron microscope (SEM) produced by Hitachi, with an acceleration voltage of 20 kV.

[0105] The composition of the samples, including the content of alkaline metal oxides, was determined using a 3271E type X-ray fluorescence spectrometer (XRF) produced by Rigaku Corporation of Japan. 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.

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

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

[0108] Preparation Example 1-1

[0109] Mix aluminum sulfate, hexamethylenediamine hydroxide (HMOH), sodium hydroxide, and deionized water in a certain ratio, stir for 30 min, and then add silica sol. The molar ratios of various substances are n(Al2O3):(HMOH):n(Na + ):n(H2O):n(SiO2) = 0.01:0.03:0.3:8:1. Transfer the mixture to a crystallization kettle and crystallize it for 6 h under stirring at room temperature with a stirring speed of 400 rpm; then crystallize it for 24 h at 80 °C, and then raise the temperature to 180 °C and crystallize for 48 h. After crystallization, filter, and dry the solid product at 120 °C for 6 h. The obtained product is seed crystal A1. After crystallization, filter and dry the obtained product to get seed crystal A1. The XRD diffraction peaks of seed crystal 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° is 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] Mix sodium aluminate, hexamethylenediamine chloride (HMCl), sodium hydroxide, and deionized water 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) = 0.004:0.03:0.3:21:1. Transfer the mixture to a crystallization kettle and crystallize it for 12 h under stirring at room temperature with a stirring speed of 350 rpm; crystallize it for 12 h at 60 °C and for 48 h at 160 °C. After crystallization, filter, and dry the product at 120 °C for 6 h. After crystallization, filter and dry the obtained product to get 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° is 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] Mix sodium aluminate, hexamethylenediamine chloride (HMCl), sodium hydroxide, and deionized water 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) = 0.004:0.03:0.3:21:1. 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 , 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 the 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 ZSM-48 seed A1 with 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 dried 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, and the scanning electron microscope pictures are shown in Figure 3 , its morphology was ellipsoidal, 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 the 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%, and ZSM-48 seed crystal A2 accounting for 15% of the mass of the added SiO2 is added;

[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 proportion, 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. ZSM-48 seed crystal A3 accounting for 25% of the mass of the added SiO2 is added. 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] The following preparation examples are used to illustrate the preparation of the hydroisomerization catalyst.

[0133] Preparation Example 3-1

[0134] 70 g of the Z-1 sample from Preparation Example 2-1 was mixed with 40 g of pseudoboehmite 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.

[0135] Platinum dichloride tetraammine (with a Pt mass fraction of 57.3%) was poured into 100 g of deionized water and stirred until homogeneous. 100 g of the 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 stream at a calcination temperature of 450 °C for 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%.

[0136] Preparation Example 3-2

[0137] 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.

[0138] Comparative Preparation Example 3-1

[0139] 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.

[0140] Comparative Preparation Example 3-2

[0141] 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, and 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.

[0142] Table 2

[0143]

[0144] Example 1

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

[0146] The hydrotreating reaction zone is filled with 100 mL of hydrotreating catalyst I, the carrier of which is alumina. Based on the oxide and taking hydrotreating catalyst I as the reference, the content of molybdenum is 15 wt%.

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

[0148] Catering waste oil A and hydrogen enter the hydrotreating reaction zone together. Dimethyl disulfide as a sulfurizing agent is added to catering waste oil A, and the concentration of the sulfurizing agent is 0.2 wt%. Under the hydrotreating reaction conditions, it contacts with the sulfurized 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 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 A 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.

[0149] The obtained liquid hydrocarbons enter the hydroisomerization reaction zone and react with the hydroisomerization catalyst under the hydroisomerization reaction conditions. After the obtained hydroisomerization reaction effluent is separated and fractionated, a biodiesel fraction is obtained. The hydroisomerization reaction conditions are: reaction pressure 5.0 MPa, reaction temperature 305 °C, volume space velocity 1.0 h -1 and hydrogen-oil volume ratio 500. The liquid product yield in the hydroisomerization reaction zone is 98.5 wt%, the yield of the biodiesel fraction (boiling range 160 - 350 °C) is 97.5 wt%, and the pour point and cold filter plugging point meet the requirements of -10 diesel.

[0150] Based on catering waste oil A, the yield of the biodiesel fraction is 82.9 wt%.

[0151] Example 2

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

[0153] The hydrotreating reaction zone is filled successively with 90 mL of hydrotreating catalyst I and 10 mL of hydrotreating catalyst II; 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 12 wt%; the carrier of hydrotreating catalyst II is alumina. Based on the oxide and taking hydrotreating catalyst II as the reference, the content of nickel is 4.2 wt%, and the content of molybdenum is 26.5 wt%.

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

[0155] 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 the 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: reaction pressure 6.4 MPa, reaction temperature 320 °C, volume space velocity 0.5 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 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 7 μg / g, and the nitrogen content is 1 μg / g.

[0156] The obtained liquid hydrocarbons enter the hydroisomerization reaction zone and, under the hydroisomerization reaction conditions, contact with the hydroisomerization catalyst for reaction. After the obtained hydroisomerization reaction effluent is separated and fractionated, a biodiesel fraction is obtained. The hydroisomerization reaction conditions are: reaction pressure 7.0 MPa, reaction temperature 320 °C, volume space velocity 1.0 h -1 and hydrogen-oil volume ratio 600. The liquid product yield in the hydroisomerization reaction zone is 98 wt%, and the yield of the biodiesel fraction (boiling range 160 - 350 °C) is 96 wt%. The pour point and cold filter plugging point meet the requirements of -20 diesel.

[0157] Based on catering waste oil B, the yield of the biodiesel fraction is 80.6 wt%.

[0158] Example 3

[0159] In this example, catering waste oil C is used as the oil raw material, and the main properties of catering waste oil C are shown in Table 3.

[0160] The hydrotreating reaction zone is filled with 100 mL of hydrotreating catalyst catalyst II; the carrier of hydrotreating catalyst II is alumina. Based on oxides and taking hydrotreating catalyst II as the benchmark, the nickel content is 4.2 wt%, and the molybdenum content is 26.5 wt%.

[0161] The hydroisomerization reaction zone is filled with 100 mL of hydroisomerization catalyst CAT-2.

[0162] Catering waste oil C and hydrogen enter the hydrotreating reaction zone together. Dimethyl disulfide, a sulfurizing agent, is added to catering waste oil C, and the concentration of the sulfurizing agent is 0.25 wt%. Under the hydrotreating reaction conditions, it reacts with the sulfided hydrotreating catalyst II to obtain a hydrotreating reaction effluent. The hydrotreating reaction conditions are as follows: reaction pressure 6.0 MPa, reaction temperature 330 °C, volumetric space velocity 0.8 h -1 and hydrogen-oil volume ratio 1200. 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 C is 100%, the final boiling point temperature of the obtained liquid hydrocarbons is less than 350 °C, the liquid hydrocarbon yield is 82 wt%, in the obtained liquid hydrocarbons, the content of even-carbon-chain alkanes is 49 wt%, the sulfur content is 3 μg / g, and the nitrogen content is 1 μg / g.

[0163] The obtained liquid hydrocarbons enter the hydroisomerization reaction zone and react with the hydroisomerization catalyst under the hydroisomerization reaction conditions. After the obtained hydroisomerization reaction effluent is separated and fractionated, a biodiesel fraction is obtained. The hydroisomerization reaction conditions are as follows: reaction pressure 7.0 MPa, reaction temperature 320 °C, volumetric space velocity 1.0 h -1 and hydrogen-oil volume ratio 600. The liquid product yield in the hydroisomerization reaction zone is 97.5 wt%, and the yield of the biodiesel fraction (boiling range 160 - 350 °C) is 95 wt%. The pour point and cold filter plugging point meet the requirements of -20 diesel.

[0164] Based on catering waste oil C, the yield of the biodiesel fraction is 77.9 wt%.

[0165] Comparative Example 1

[0166] In this comparative example, catering waste oil A is used as the oil raw material, and the main properties of catering waste oil A are shown in Table 3.

[0167] 100 mL of hydrotreating catalyst I is loaded in the hydrotreating reaction zone. Its carrier is alumina, and based on the oxide and taking hydrotreating catalyst I as the reference, the content of molybdenum is 15 wt%.

[0168] 100 mL of hydroisomerization catalyst RIW-2 is loaded in the hydroisomerization reaction zone. This hydroisomerization catalyst is produced by the Catalyst Branch of Sinopec.

[0169] Catering waste oil A and hydrogen enter the hydrotreating reaction zone together. Dimethyl disulfide, a sulfurizing agent, is added to catering waste oil A, and the concentration of the sulfurizing agent is 0.2 wt%. Under the hydrotreating reaction conditions, it reacts with the sulfided hydrotreating catalyst I to obtain a hydrotreating reaction effluent. The hydrotreating reaction conditions are as follows: reaction pressure 6.4 MPa, reaction temperature 310 °C, volumetric space velocity 1.0 h -1And a hydrogen-oil volume ratio of 1000. The obtained hydrotreating reaction effluent is subjected to gas-liquid separation to obtain a liquid hydrocarbon, water, and gas stream. The conversion rate of the waste cooking oil A is 100%, the final boiling point temperature of the obtained liquid hydrocarbon is less than 350 °C, the liquid hydrocarbon yield is 85% by weight, and the content of even-carbon-chain alkanes in the obtained liquid hydrocarbon is 96% by weight.

[0170] The obtained liquid hydrocarbon enters the hydroisomerization reaction zone and reacts with a hydroisomerization catalyst under hydroisomerization reaction conditions. After the obtained hydroisomerization reaction effluent is separated and fractionated, a biodiesel fraction is obtained. The hydroisomerization reaction conditions are as follows: reaction pressure 5.0 MPa, reaction temperature 305 °C, volume space velocity 1.0 h -1 And a hydrogen-oil volume ratio of 500. The liquid product yield in the hydroisomerization reaction zone is 92% by weight, and the yield of the biodiesel fraction (boiling range 160 - 350 °C) is 85% by weight. The pour point and cold filter plugging point meet the requirements of -10 diesel.

[0171] Based on the waste cooking oil A, the yield of the biodiesel fraction is 72.3% by weight.

[0172] Comparative Example 2

[0173] In this example, waste cooking oil B is used as the oil-based raw material, and the main properties of waste cooking oil B are shown in Table 3.

[0174] The hydrotreating reaction zone is filled with 90 mL of hydrotreating catalyst I and 10 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 12% by weight; the carrier of hydrotreating catalyst II is alumina, and based on oxides and based on hydrotreating catalyst II, the content of nickel is 4.2% by weight, and the content of molybdenum is 26.5% by weight.

[0175] The hydroisomerization reaction zone is filled with 100 mL of hydroisomerization catalyst DCAT-1.

[0176] Waste cooking oil B and hydrogen enter the hydrotreating reaction zone together. Dimethyl disulfide, a sulfurizing agent, is added to waste cooking oil B, and the concentration of the sulfurizing agent is 0.25% by weight. Under hydrotreating reaction conditions, it reacts with the sulfurized hydrotreating catalyst I and hydrotreating catalyst II to obtain a hydrotreating reaction effluent. The hydrotreating reaction conditions are as follows: reaction pressure 6.4 MPa, reaction temperature 320 °C, volume space velocity 0.5 h -1And the hydrogen-oil volume ratio is 1000. The obtained hydrotreating reaction effluent is subjected to gas-liquid separation to obtain a liquid hydrocarbon, water and gas stream. The conversion rate of the waste cooking oil B is 100%, the final boiling point temperature of the obtained liquid hydrocarbon is less than 350 °C, the liquid hydrocarbon yield is 84% by weight, and in the obtained liquid hydrocarbon, the content of even-carbon-chain alkanes is 94% by weight, the sulfur content is 7 μg / g, and the nitrogen content is 1 μg / g.

[0177] The obtained liquid hydrocarbon enters the hydroisomerization reaction zone and reacts with a hydroisomerization catalyst under hydroisomerization reaction conditions. After the obtained hydroisomerization reaction effluent is separated and fractionated, a biodiesel fraction is obtained. The hydroisomerization reaction conditions are as follows: reaction pressure 7.0 MPa, reaction temperature 320 °C, space velocity 1.0 h -1 And the hydrogen-oil volume ratio is 600. The liquid product yield in the hydroisomerization reaction zone is 95.8% by weight, and the yield of the biodiesel fraction (boiling range 160 - 350 °C) is 85% by weight, and the pour point and cold filter plugging point meet the requirements of No. -20 diesel.

[0178] Based on the waste cooking oil B, the yield of the biodiesel fraction is 71.4% by weight.

[0179] Comparative Example 3

[0180] 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.

[0181] 90 mL of hydrotreating catalyst I and 10 mL of hydrotreating catalyst II are successively loaded in the hydrotreating reaction zone; the carrier of the hydrotreating catalyst I is alumina, and based on oxides and based on the hydrotreating catalyst I, the content of molybdenum is 12% by weight; the carrier of the hydrotreating catalyst II is alumina, and based on oxides and based on the hydrotreating catalyst II, the content of nickel is 4.2% by weight, and the content of molybdenum is 26.5% by weight.

[0182] 100 mL of hydroisomerization catalyst DCAT-2 is loaded in the hydroisomerization reaction zone.

[0183] Waste cooking oil B and hydrogen enter the hydrotreating reaction zone together. Dimethyl disulfide as a sulfurizing agent is added to the waste cooking oil B, and the concentration of the sulfurizing agent is 0.25% by weight. Under the hydrotreating reaction conditions, it reacts with the sulfurized hydrotreating catalyst I and hydrotreating catalyst II to obtain a hydrotreating reaction effluent. The hydrotreating reaction conditions are as follows: reaction pressure 6.4 MPa, reaction temperature 320 °C, space velocity 0.5 h -1And the hydrogen-oil volume ratio is 1000. The obtained hydrotreating reaction effluent is subjected to gas-liquid separation to obtain a liquid hydrocarbon, water and gas stream. The conversion rate of the waste cooking oil B is 100%, the final boiling point temperature of the obtained liquid hydrocarbon is less than 350 °C, the liquid hydrocarbon yield is 84% by weight, in the obtained liquid hydrocarbon, the content of even-carbon-chain alkanes is 94% by weight, the sulfur content is 7 μg / g, and the nitrogen content is 1 μg / g.

[0184] The obtained liquid hydrocarbon enters the hydroisomerization reaction zone and reacts with a hydroisomerization catalyst under hydroisomerization reaction conditions. After the obtained hydroisomerization reaction effluent is separated and fractionated, a biodiesel fraction is obtained. The hydroisomerization reaction conditions are: reaction pressure 7.0 MPa, reaction temperature 320 °C, volume space velocity 1.0 h -1 And the hydrogen-oil volume ratio is 600. The liquid product yield in the hydroisomerization reaction zone is 93.88% by weight, and the yield of the biodiesel fraction (boiling range 160 - 350 °C) is 83% by weight. The pour point and cold filter plugging point meet the requirements of No. -20 diesel.

[0185] Based on the waste cooking oil B, the yield of the biodiesel fraction is 69.7% by weight.

[0186] It can be seen from the above examples that by the method of the present invention, biodiesel products meeting the requirements of No. -10 and No. -20 diesel are successfully produced from waste cooking oil as raw materials, and the yield of the target products is effectively improved.

[0187] Table 3

[0188] Item Food waste oil A Food waste oil B Food waste oil C <![CDATA[Density (20 °C), g / cm 3 > 918.9 919.1 916 Sulfur content, μg / g 28 33 55 Nitrogen content, μg / g 49 143 186 Oxygen content, wt% 11 10.55 11.2 Total acid value, mgKOH / g 3.2 13 32

Claims

1. A method for producing a biodiesel fraction from an oil and fat raw material, comprising: (1) The oil and fat raw material and hydrogen enter a hydrotreating reaction zone 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. (2) The hydrotreating reaction effluent obtained in step (1) is separated to obtain a liquid hydrocarbon, water, and a gas stream. (3) The liquid hydrocarbon obtained in step (2) enters a hydroisomerization reaction zone and reacts under hydroisomerization reaction conditions in contact with a hydroisomerization catalyst. The hydroisomerization reaction effluent obtained is separated to obtain a biodiesel fraction. 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 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, wherein The oil and fat raw material is animal and vegetable oils and / or waste cooking oil. When the sulfur content and nitrogen content in the oil and fat raw material are both <50 μg / g, the hydrotreating reaction zone is filled with the hydrotreating catalyst I. When the sulfur content and nitrogen content in the oil and fat raw material are both between 50-150 μg / g, the hydrotreating reaction zone is filled with the hydrotreating catalyst I and the hydrotreating catalyst II, and the filling volume ratio of the hydrotreating catalyst I to the hydrotreating catalyst II is 1:9-9:

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

3. The method according to claim 1 or 2, characterized in that 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, 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 , hydrogen-to-oil volume ratio is 300 - 2000 Nm 3 / m 3 ; The preferred hydrotreating reaction conditions are as follows: reaction temperature is 300 - 400 °C, reaction pressure is 4.0 - 8.0 MPa, volumetric space velocity is 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 sequentially enters a stripping tower for stripping and a dehydration tower for dehydration to remove dissolved hydrogen sulfide, ammonia, and water to obtain a liquid hydrocarbon.

7. 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 - 10.0 MPa, volume hourly space velocity is 0.1 - 10.0 h -1 , and hydrogen-to-oil volume ratio is 200 - 1500 Nm 3 / m 3 ; The preferred hydroisomerization reaction conditions are as follows: reaction temperature 280 - 350 °C, reaction pressure 2.0 - 8.0 MPa, space velocity 0.5 - 5.0 h -1 , hydrogen-oil volume ratio 500 - 1000 Nm 3 / m 3 .

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

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% 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, characterized in that The method for preparing the hydroisomerization catalyst comprises the following steps: Step 1: Shaping the dry powder of ZSM-48 molecular sieve to obtain a shaped carrier; The molar ratio of silica to alumina in the ZSM-48 molecular sieve is not less than 40, and the specific surface area of the ZSM-48 molecular sieve is not less than 200 m 2 / g. The crystal grains of the ZSM-48 molecular sieve are ellipsoidal, with the major axis not exceeding 700 nm and the aspect ratio being 1-3:1; Among them, based on the mass of the dry powder of ZSM-48 molecular sieve, the water content of the dry powder of 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, preferably pseudoboehmite.

13. The method according to claim 12, wherein 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 2 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, 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 of the drying is 80 - 120 °C, and the drying time is 2 - 6 hours; The temperature of the calcination is 400 - 500 °C, and the calcination time is 2 - 6 hours.

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