Crude oil hydrocracking method

Abstract

The present invention relates to the technical field of crude oil processing, and discloses a crude oil hydrocracking method, which comprises: feeding a crude oil raw material into a pre-fractionating tower, and separating a tower top naphtha fraction, a side line jet fuel fraction and a tower bottom oil fraction in the pre-fractionating tower, tower bottom oil and hydrogen-rich gas are mixed and then sequentially pass through a protective reaction unit, a hydrotreating reaction unit and a hydrocracking reaction unit, reaction products are subjected to separation and fractionation to obtain light naphtha, heavy naphtha, jet fuel, middle distillate oil and tail oil fraction, and the tail oil fraction can be used as a lubricating oil base oil raw material. By adopting the method disclosed by the invention, clean oil products, chemical raw materials and lubricant base oil raw materials can be directly produced from crude oil in a short process.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of crude oil processing, in particular to a method for hydrocracking of crude oil. BACKGROUND

[0002] In China, the demand growth rate of vehicle gasoline and diesel in finished oil is slowing down, while the demand of jet fuel is continuously growing, and is expected to reach the peak demand in 2050; at the same time, a considerable proportion of high-end lubricating oil still needs to be imported from abroad, so it is of great practical significance to develop a hydrocracking technology that can produce jet fuel and high-end lubricating oil at the same time.

[0003] Under the crude oil processing flow of conventional refineries, the crude oil is usually cut and fractionated into several narrow fractions, and then processed separately to produce fuel oil, and a small amount of unconverted hydrocracking tail oil is used as lubricating oil, which is processed by isomerization and condensation to produce lubricating oil base oil. With this processing flow, a high proportion of vehicle diesel is usually produced, and the product has low added value; in addition, due to the multiple cutting and separate processing of the crude oil, there are problems of long process flow, high investment cost, high operating cost and high energy consumption.

[0004] CN105358661A and CN109593556A disclose a method and a facility for converting crude oil into petrochemicals with improved propylene yield. The method first produces gas, kerosene and or gas oil and residual oil by distilling the crude oil, on the one hand, LPG and upgraded effluent are produced by upgrading the residual oil; on the other hand, the upgraded effluent is subjected to at least 50% ring opening of aromatic rings to produce petrochemical products with kerosene and gas oil.

[0005] CN104093821A discloses a method for directly processing crude oil, including hydrogen redistribution and integrated hydroprocessing and steam pyrolysis. The method first separates the crude oil into light components and heavy components, and the heavy components are subjected to hydrogenation to produce effluent with reduced pollutant content, reduced paraffin content and BMCI value, and then the heavy fraction hydrogenation effluent and light components are introduced into a steam pyrolysis zone to produce olefin and aromatic chemical products.

[0006] CN106103664A discloses an integrated hydrocracking method. The method subjects crude oil and feedstock from coking to hydroprocessing in a first hydrogenation reaction zone to obtain a stream separated into LPG and a liquid stream, and the liquid stream is introduced into a second hydrocracking zone to produce a BTEXE stream, a stream containing LPG and residual liquid, and the residual liquid stream is subjected to thermal cracking to produce coking liquid products and petroleum coke.

[0007] In general, the existing crude oil hydrocracking methods disclosed in the prior art all have problems of long process flow, high energy consumption of separation operation, etc., and there is no related technical report on short process for directly converting the whole fraction of crude oil into jet fuel, chemical raw materials and lubricating oil. SUMMARY

[0008] The present application aims to solve the problems of long process, high investment and operation cost in the prior art for producing jet fuel and lubricating oil from crude oil.

[0009] In order to achieve the above-mentioned purpose, the present application provides a method for hydrocracking of crude oil, which comprises:

[0010] (1) introducing a crude oil raw material into a pre-fractionating column for separation to obtain a top naphtha fraction, a side-cut jet fuel fraction and a bottom oil fraction; the cut end point of the top naphtha fraction is 140-175℃, and the cut end point of the side-cut jet fuel fraction is 220-280℃;

[0011] (2) subjecting the bottom oil fraction to hydroprocessing in sequence through a guard reaction unit, a hydroprocessing reaction unit and a hydrocracking reaction unit in the presence of hydrogen-rich gas to obtain a reaction effluent;

[0012] (3) subjecting the reaction effluent to fractionation to obtain light naphtha, heavy naphtha, jet fuel, middle distillate oil and tail oil fraction;

[0013] In step (2), at least two catalyst beds are provided in the guard reaction unit, the catalysts in each catalyst bed have the same catalyst grading mode, and each catalyst bed is filled with a hydrogenation guard catalyst and a hydrodemetallization catalyst; the volume ratio of the hydrogenation guard catalyst to the hydrodemetallization catalyst is 80%:20% to 20%:80% based on the volume of the catalyst bed;

[0014] The hydroprocessing reaction unit is filled with at least two kinds of hydrofining catalysts rich in large-pore carriers, and the K value of the hydrofining catalysts decreases in sequence in the flow direction of the liquid phase stream; the K value of the upstream hydrofining catalyst is 20%-40% higher than that of the downstream hydrofining catalyst; the K value is the ratio of the pore volume of >10nm in the hydrofining catalyst to the total pore volume;

[0015] The hydrocracking reaction unit is filled with at least two kinds of hydrocracking catalysts containing Y-type molecular sieve, and the content of Y-type molecular sieve in the hydrocracking catalyst in the upstream bed is 50%-200% higher than that in the adjacent downstream bed based on the total weight of the carrier.

[0016] The present application is a method for short-process processing of crude oil to directly produce jet fuel, chemical raw materials and lubricating oil.

[0017] Specifically, the present application provides a crude oil hydrocracking method, preferably the crude oil raw material after electro-desalting and dehydration is first introduced into a pre-fractionating tower, the pre-fractionating tower separates a top naphtha fraction, a side-line jet fuel fraction and a bottom oil fraction, the bottom oil is mixed with hydrogen-rich gas and then sequentially passes through a guard reaction unit, a hydroprocessing reaction unit and a hydrocracking reaction unit, and the reaction product is separated and fractionated to obtain light naphtha, heavy naphtha, jet fuel, middle distillate oil and tail oil fraction, wherein the tail oil fraction can be used as a lubricating oil base oil raw material.

[0018] By using the method of the present application, clean oil products, chemical raw materials and lubricating oil base oil raw materials can be directly produced from crude oil in a short process. DETAILED DESCRIPTION

[0019] The endpoints of the ranges and any values disclosed herein are not limited to the precise values recited as the exact dimensions are not critical to the present application. Any numerical values need not be a precision value, provided that these values are treated as approximations. The endpoints of the ranges of values recited are not to be understood as limiting. The exact numerical values are approximations.

[0020] The specific surface area of the catalyst of the present application is determined according to the standard NB / SH / T 0571-2021.

[0021] The matrix specific surface area of the catalyst of the present application is determined according to the NB_SH_T 0571-2021 Zeolite Specific Surface Area and Pore Volume Determination Method in Catalysts and the GB_T 5816-1995 Method for Determining the Surface Area of Catalysts and Adsorbents.

[0022] The t-plot method for determining the pore size analysis of the present application refers to the SH_T 0572-1993 Catalyst Pore Size Distribution Calculation Method (Nitrogen Desorption Isotherm Calculation Method), and the pore volume refers to the NB_SH_T 0571-2021 Zeolite Specific Surface Area and Pore Volume Determination Method in Catalysts, whereby the total pore volume and the pore volume greater than 10 nm of the catalyst can be obtained by the two methods.

[0023] As described above, the present application provides a method for hydrocracking of crude oil, which comprises:

[0024] (1) introducing a crude oil raw material into a pre-fractionating tower for separation to obtain a top naphtha fraction, a side-line jet fuel fraction and a bottom oil fraction; the cut end point of the top naphtha fraction is 140-175℃, and the cut end point of the side-line jet fuel fraction is 220-280℃;

[0025] (2) subjecting the column bottom oil fraction to hydrotreatment in sequence in a guard reaction unit, a hydrotreating reaction unit and a hydrocracking reaction unit in the presence of hydrogen-rich gas to obtain a reaction effluent;

[0026] (3) subjecting the reaction effluent to fractionation to obtain light naphtha, heavy naphtha, jet fuel, middle distillate oil and tail oil fraction;

[0027] In step (2), at least two catalyst beds are provided in the guard reaction unit, the catalysts in each catalyst bed have the same catalyst grading mode, and each catalyst bed is packed with hydrogenation guard catalyst and hydrogenation demetallization catalyst, and the volume ratio of the hydrogenation guard catalyst to the hydrogenation demetallization catalyst is 80%:20% to 20%:80% based on the volume of the catalyst bed packing;

[0028] The hydrotreating reaction unit is packed with at least two kinds of hydrofining catalysts rich in large-pore carriers, and the K value of the hydrofining catalysts decreases in sequence in the flow direction of the liquid phase stream; and the K value of the upstream hydrofining catalyst is 20%-40% higher than that of the downstream hydrofining catalyst; the K value is the ratio of the pore volume of >10 nm in the hydrofining catalyst to the total pore volume;

[0029] The hydrocracking reaction unit is packed with at least two kinds of hydrocracking catalysts containing Y-type molecular sieve, and the content of Y-type molecular sieve in the hydrocracking catalyst in the upstream bed is 50%-200% higher than that in the adjacent downstream bed based on the total weight of the carrier in the flow direction of the liquid phase stream.

[0030] In the present application, at least two kinds of hydrofining catalysts are packed in the hydrotreating reaction unit, and the ratio of the pore volume of >10 nm in the hydrofining catalyst to the total pore volume decreases in sequence in the flow direction of the reaction stream, and the ratio of the pore volume of >10 nm in the hydrofining catalyst in the upper part of the bed to the total pore volume is 20%-40% higher than that in the lower part of the bed. Under such catalyst scheme, the method provided by the present application can not only promote the conversion of large molecules in crude oil, but also improve the saturation rate of hydrocarbon molecules of monocyclic aromatic hydrocarbons in the raw material. In addition, in the present application, the grading and packing mode of the hydrocracking reaction unit can reduce the conversion of alkanes in the tail oil as much as possible, which is helpful for the method of the present application to directly produce clean oil, chemical raw materials and lubricating oil base oil raw materials in a short process.

[0031] Preferably, the cut end point of the side line jet fuel fraction is 220-250°C. Under this cutting scheme, the product naphtha obtained by the process of the present application can be used as ethylene feed, and the product jet fuel can meet the index requirements of No. 3 jet fuel; in addition, by separating naphtha and jet fuel, the processing capacity of the hydrocracking unit can be reduced, achieving the purpose of further reducing equipment investment.

[0032] In the present application, in the conventional crude oil demetallization process, the catalyst bed usually located at the upper part (feed side) of the reactor is prone to deposit more metal Fe and Ca and form a cap, thereby causing the pressure drop at the top of the catalyst bed to rapidly increase and leading to the shutdown of the device, while the catalyst located at the lower part of the reactor still has higher activity but cannot play a role. In order to solve the problems of high metal content in crude oil, fast deposition rate, high pressure drop of catalyst, and low overall utilization rate of catalyst, in the preferred case, in step (2), a feed inlet is arranged in each catalyst bed, when the pressure drop of the i-th catalyst bed increases to a set value a, the inlet feed of the i-th catalyst bed is cut off and the material from the (i-1)-th catalyst bed is introduced into the feed inlet of the (i+1)-th catalyst bed, i≥1, and a is 0.35-0.5 MPa. That is, in the present application, a bed switchable operation protection reaction unit is preferably arranged, the protection reaction unit is provided with at least one protection reactor and a feed line and valve capable of changing the feed position, the protection reactor is provided with n catalyst beds (n≥2), the inlet of the protection reactor and the catalyst beds are provided with feed inlets and are connected with the feed line, a feed flow switching control valve is arranged on the line, and the feed position of the reactor can be flexibly adjusted by the switching control valve.

[0033] In the present application, in order to solve the problems of shortening of the device running period and low utilization rate of the catalyst caused by high metal content in crude oil, according to a preferred specific embodiment, the protection reaction unit is provided with at least one protection reactor and a feed line and valve capable of changing the feed position, the protection reactor is provided with n catalyst beds (n≥2), the catalyst beds are sorted as i along the reaction material flow direction and satisfy i∈n; the inlet of the protection reactor and the catalyst beds are provided with feed inlets and are connected with the feed line, a feed flow switching control valve is arranged on the line, and the feed position of the reactor can be flexibly adjusted by the switching control valve; during the operation of the device, the catalyst beds gradually deposit metal and cause the pressure drop of the catalyst beds to increase, when the pressure drop of the i-th catalyst bed increases to a set value a, the inlet feed of the i-th bed is cut off and the feed position is changed to the feed inlet of the (i+1)-th bed, and the set value a is in the range of 0.35-0.5 MPa; by this method, the bed with pressure drop can be cut off, and the subsequent catalyst beds continue to carry out the demetallization of the raw material.

[0034] More preferably, in the protection reaction unit, the hydrogenation protection catalyst comprises a carrier and an active metal component, the carrier is alumina, the active metal component contains at least one Group VIII metal element and at least one Group VIB metal element, the Group VIII metal element is nickel and / or cobalt, and the Group VIB metal element is molybdenum and / or tungsten; the content of the Group VIII metal element is 0.3wt%-5wt% and the content of the Group VIB metal element is 1wt%-10wt% based on the total weight of the hydrogenation protection catalyst in terms of oxides.

[0035] According to a particularly preferred specific embodiment, the protection reaction unit of the present application is filled with 3 kinds of hydrogenation protection catalysts; the filling volume ratio of the upstream, midstream and downstream hydrogenation protection catalysts is 1:0.8-1.2:0.8-1.2 in the flow direction of the liquid phase stream.

[0036] Preferably, in the protection reaction unit, the hydrogenation demetallization catalyst comprises a carrier and an active metal component, the carrier is alumina, the active metal component contains at least one Group VIII metal element and at least one Group VIB metal element, the Group VIII metal element is nickel and / or cobalt, and the Group VIB metal element is molybdenum and / or tungsten; the content of the Group VIII metal element is 1wt%-5wt% and the content of the Group VIB metal element is 1wt%-15wt% based on the total weight of the hydrogenation demetallization catalyst in terms of oxides.

[0037] According to a particularly preferred specific embodiment, the protection reaction unit of the present application is filled with 3 kinds of hydrogenation demetallization catalysts; the filling volume ratio of the upstream, midstream and downstream hydrogenation demetallization catalysts is 1:0.8-1.2:1.5-3 in the flow direction of the liquid phase stream.

[0038] According to a particularly preferred specific embodiment, the conditions of the protection reaction unit are controlled so that the metal removal rate of the protection reaction unit is 95%-100% and the asphaltene removal rate is 85%-100%.

[0039] Preferably, the reaction conditions of the protection reaction unit include: the reaction pressure is 8.0MPa-20.0MPa, the reaction temperature is 260℃-420℃, the liquid hourly space velocity is 0.5h -1 -15h -1 , and the hydrogen / oil volume ratio is 50-600.

[0040] Preferably, in the hydrogenation treatment reaction unit, in the hydrogenation refining catalyst, the large-pore carrier is an alumina carrier and / or an alumina-silica carrier.

[0041] Preferably, in the hydroprocessing reaction unit, the hydrofining catalyst further contains Group VIII metal elements and Group VIB metal elements, the Group VIII metal elements are nickel and / or cobalt, and the Group VIB metal elements are molybdenum and / or tungsten; the content of the Group VIII metal elements is 1wt%-15wt% and the content of the Group VIB metal elements is 5wt%-40wt% based on the total weight of the hydrofining catalyst in terms of oxides.

[0042] To further remove impurities of large molecular compounds in the crude oil and further protect aromatics, it is particularly preferred that, in the hydroprocessing reaction unit, the K value of the upstream hydrofining catalyst is 65%-85%. The upstream hydrofining catalyst refers to the hydrofining catalyst loaded in the upstream bed.

[0043] To further satisfy the saturation of monocyclic aromatic hydrocarbons in the crude oil and further reduce the cracking of paraffins, it is preferred that, in the hydroprocessing reaction unit, the downstream hydrofining catalyst does not contain F elements and P elements in the large-pore support.

[0044] Preferably, the reaction conditions of the hydroprocessing reaction unit include: the reaction pressure is 8.0MPa-20.0MPa, the reaction temperature is 280°C-400°C, the liquid hourly space velocity is 0.5h -1 -6h -1 , and the hydrogen to oil volume ratio is 300-2000.

[0045] To further reduce the conversion of high-quality alkane components in the lubricating oil, according to a preferred specific embodiment, the nitrogen content of the hydrofining oil in the bottom oil fraction is less than 20μg / g, and the reaction conditions of the hydroprocessing reaction unit are controlled so that the conversion rate of the >370°C fraction is 6%-18%;

[0046] The conversion rate of the >370°C fraction = 100% x (the mass of the >370°C fraction in the bottom oil fraction at the inlet of the protection reaction unit - the mass of the >370°C fraction in the generated oil in the hydroprocessing reaction unit) / the mass of the >370°C fraction in the bottom oil fraction at the inlet of the protection reaction unit.

[0047] To further reduce the conversion of paraffin components in the lubricating oil, it is preferred that, in the direction of flow of the liquid phase stream, the content of Y-type molecular sieve in the hydrocracking catalyst of the upstream bed is 50%-100% higher than the content of Y-type molecular sieve in the hydrocracking catalyst of the adjacent downstream bed based on the total weight of the support.

[0048] Preferably, the hydrocracking catalyst further comprises a heat-resistant inorganic oxide and an active metal component, the heat-resistant inorganic oxide is selected from at least one of silicon oxide, aluminum oxide, amorphous aluminum silicate; the active metal component comprises at least one Group VIII metal element and at least one Group VIB metal element; the content of the Group VIB metal element is 15wt%-35wt% and the content of the Group VIII metal element is 2wt%-8wt% in terms of oxide, based on the total weight of the hydrocracking catalyst.

[0049] Preferably, in the hydrocracking catalyst of the downstream bed, the content of the Y-type molecular sieve is 1wt%-15wt% based on the total weight of the carrier, and the balance is the heat-resistant inorganic oxide.

[0050] According to a particularly preferred specific embodiment, the hydroprocessing reaction unit is packed with two hydrofining catalysts rich in large-pore carriers, and the packing volume ratio of the upstream hydrofining catalyst to the downstream hydrofining catalyst is 1:4 to 4:1.

[0051] According to another preferred specific embodiment, the hydrocracking reaction unit is packed with two hydrocracking catalysts containing Y-type molecular sieves, and the packing volume ratio of the upstream hydrocracking catalyst to the downstream hydrocracking catalyst is 1:4 to 4:1.

[0052] Preferably, the reaction conditions of the hydrocracking reaction unit include: the reaction pressure is 8.0MPa-20.0MPa, the reaction temperature is 290℃-420℃, the liquid hourly space velocity is 0.3h -1 -5h -1 , and the hydrogen to oil volume ratio is 300-2000.

[0053] To produce higher-end lubricating oil products, more preferably, the reaction temperature of the hydrocracking reaction unit is 370℃-410℃.

[0054] According to a particularly preferred specific embodiment, the conditions are controlled so that the cracking conversion rate of the hydrocracking reaction unit is 35%-74%;

[0055] The cracking conversion rate = 100% x (the mass yield of >370℃ fraction in the bottom oil fraction feed at the inlet of the protection reaction unit - the mass yield of >370℃ fraction in the liquid reaction effluent obtained in the hydrocracking reaction unit) / the mass yield of >370℃ fraction in the bottom oil fraction feed at the inlet of the protection reaction unit.

[0056] To further improve the quality of lubricating oil products, preferably, the API degree of the crude oil feedstock is 35-50.

[0057] In order to further prolong the continuous operation cycle of the device, preferably, the Fe element content in the crude oil raw material is ≯ 20 μg / g, the Ca element content is ≯ 20 μg / g, the Ni element content is ≯ 10 μg / g, the V element content is ≯ 10 μg / g, the carbon residue mass fraction is ≯ 4%, and the asphaltene content is ≯ 6000 μg / g.

[0058] Further preferably, the method further comprises: before entering the pre-fractionating tower, the crude oil raw material is subjected to desalting and dewatering treatment, and the salt content of the desalted crude oil raw material is less than 2.0 mg / L, and the water content of the dewatered crude oil raw material is less than 0.1 wt%.

[0059] The application will be described in detail below by examples.

[0060] In the following examples, the cut end boiling point of the naphtha fraction at the top of the pre-fractionating tower is 145 DEG C, the cut end boiling point of the jet fuel fraction at the side line of the pre-fractionating tower is 230 DEG C, and the remaining part is the bottom oil fraction; the properties of the crude oil raw material, the naphtha, the jet fuel and the bottom oil cut from the pre-fractionating tower are listed in Table 1.

[0061] Table 1

[0062] Item Crude oil feed 1 Naphtha Jet fuel Bottom oil Description Whole distillate crude oil <145℃ 145～230℃ >230℃ API degree 38.8 / / / Mass yield / % 100.0 13.48 20.45 66.07 Density (20°C) / (g / cm 3 )]]> 0.8267 0.7077 0.7798 0.8655 Sulfur mass fraction / % 0.180 0.0008 25 0.223 Nitrogen content / (μg / g) 100 2.7 4.5 174 Flash point (closed) / °C / / 50 / Smoke point / mm / / 29.1 / Freezing point / °C / / -53.3 / Carbon residue value / wt% 2.12 / / 3.2 Asphaltene / (μg / g) 6000 / / 9081 Metal mass fraction / (μg / g) Fe <0.1 / / <0.1 Ni 3.9 / / 5.9 V 0.9 / / 1.4 Ca 3.0 / / 4.5 Distillation range / °C D-7169 D-86 D-86 D-1160 IBP 37 40.8 159.3 226 50％ 307 98.7 190.2 384 90％ 568 124.3 218.7 488 95％ 655 144.7 231.4 533 BMCI value / 9.9 / /

[0063] As shown in Table 1, the <145 DEG C naphtha fraction is directly cut by the method of the application, the yield is 13.48%, and the BMCI value is 9.9, which can be directly used as a high-quality steam cracking ethylene device raw material; the 145 DEG C-230 DEG C fraction is cut, the yield is 20.45%, the flash point is 50 DEG C, the smoke point is 29.1 mm, the freezing point is -53.3 DEG C, and the product properties meet the requirements of No. 3 jet fuel indicators; the obtained bottom oil enters the hydrocracking reaction unit for reaction.

[0064] The protection reaction unit of the application contains three catalyst beds, and the catalyst loading conditions of each catalyst bed are the same. Taking the uppermost catalyst bed as an example, the hydrogenation protection catalysts RG-200, RG-201 and RG-202 are used, and the three kinds of hydrogenation protection catalysts are packed in equal volumes; the hydrogenation demetallization catalysts RG-30A, RG-30B and RAM-100 are packed, and the volume ratio of the three kinds of hydrogenation demetallization catalysts is 1:1:2; RG-200, RG-201, RG-202, RG-30A, RG-30B and RAM-100 are sequentially packed from top to bottom.

[0065] In the following examples, the total catalyst loading volume of the reactor single catalyst bed can be calculated from the total volume space velocity of the guard reaction unit, wherein the volume ratio of the hydrogenation guard catalyst and the hydrodemetallization catalyst is 1 :2, i.e. the volume ratio of each catalyst in each bed is RG-200: RG-201 : RG-202: RG-30A: RG-30B: RAM-100 = 1 : 1 : 1 : 1.5 : 1.5 : 3.

[0066] Hydroprocessing reaction unit catalyst:

[0067] CAT-1 hydrofinishing catalyst, the metal oxide content of the hydrofinishing catalyst CAT1 is 42.4 wt% (of which, the content of molybdenum is 5.3 wt% and the content of tungsten is 31.5 wt% and the content of nickel is 5.6 wt% in terms of oxides), and the balance is an alumina carrier; the pore volume of the pores with a pore diameter > 10 nm accounts for 70.3% of the total pore volume, and the specific surface area of the hydrofinishing catalyst CAT1 is 232.82 m 2 / g, and the substrate specific surface area accounts for 32.35% of the total specific surface area of the hydrofinishing catalyst CAT1.

[0068] CAT-2 hydrofinishing catalyst, the metal oxide content of the hydrofinishing catalyst CAT2 is 33.8% (of which, the content of molybdenum is 1.8 wt% and the content of tungsten is 28 wt% and the content of nickel is 4.0 wt% in terms of oxides), and the balance is an alumina carrier; the pore volume of the pores with a pore diameter > 10 nm accounts for 57% of the total pore volume, which is 23.3% lower than that of CAT-1 (the calculation method is: 100% x (70.3% - 57%) / 57%), and the specific surface area of the hydrofinishing catalyst CAT2 is ≮ 148 m 2 / g, and does not contain F and P.

[0069] hydrofinishing catalyst CAT3, the metal oxide content of the hydrofinishing catalyst CAT3 is 43.9 wt% (of which, the content of molybdenum is 5.6 wt% and the content of tungsten is 32 wt% and the content of nickel is 6.3 wt% in terms of oxides), and the balance is an alumina carrier; the pore volume of the pores with a pore diameter > 10 nm accounts for 82.34% of the total pore volume, and the specific surface area of the hydrofinishing catalyst CAT3 is 98.29 m 2 / g, and the substrate specific surface area accounts for 65.23% of the total specific surface area of the hydrofinishing catalyst CAT3.

[0070] Hydrocracking reaction unit catalyst:

[0071] CAT-a hydrocracking catalyst, the carrier is heat-resistant inorganic oxide and Y type molecular sieve, the heat-resistant inorganic oxide is alumina, the content of Y type molecular sieve in the carrier is 9.5wt%; in the catalyst, the content of metal oxide is 31wt% (calculated as oxide, the content of tungsten is 24.5wt%, the content of nickel is 6.4wt%).

[0072] CAT-b hydrocracking catalyst, the carrier is heat-resistant inorganic oxide and Y type molecular sieve, the heat-resistant inorganic oxide is alumina, the content of Y type molecular sieve in the carrier is 5wt%; in the catalyst, the content of metal oxide is 31wt% (calculated as oxide, the content of tungsten is 24.5wt%, the content of nickel is 6.4wt%), the content of Y type molecular sieve of CAT-a is 90% higher than that of CAT-b (the calculation method is: 100% x (9.5%-5%) / 5%).

[0073] CAT-c hydrocracking catalyst, RHC-220 catalyst, the content of molybdenum is 27.0wt% and the content of nickel is 2.7wt% calculated as oxide; the content of Y type molecular sieve in the carrier is 25wt%, the content of Y type molecular sieve of CAT-c is 400% higher than that of CAT-b (the calculation method is: 100% x (25%-5%) / 5%).

[0074] The catalysts with the above-mentioned trade marks are all produced by Sinopec Changling Catalyst Co., Ltd.

[0075] Example 1, Example 2, Example 3 and Comparative Example 1

[0076] The column bottom oil feedstock cut from crude oil is mixed with hydrogen and then passes through a guard reaction unit, a hydroprocessing reaction unit and a hydrocracking reaction unit in turn, and the reaction effluent is separated and fractionated to obtain light naphtha, heavy naphtha, jet fuel, middle distillate and tail oil fraction, the test process condition parameters and product yield and property data are listed in Table 2.

[0077] Table 2

[0078]

[0079]

[0080] As shown in Table 2, the demetallization rates of the protection reaction units of Example 1, Example 2 and Example 3 are 95%, 95% and 97%, the asphaltene removal rates are 96%, 96% and 99%, the conversion rates of the >370°C fraction of the hydrotreating reaction units are all 10.1%, the nitrogen contents of the refined oils are 7 μg / g, the cracking conversion rates (the >370°C fraction conversion rates of the hydrocracking reaction units) are 35.2%, 55.6% and 72.6% respectively, the <90°C light naphtha fraction yields are 2.1%, 3.57% and 6.5% respectively, the BMCI values are 11.0, 10.5 and 9.5 respectively, which can be used as high-quality ethylene materials; the 90-165°C heavy naphtha fraction yields are 9.9%, 16.83% and 25.5% respectively, the aromatic potential contents are 45.4%, 44.3% and 43.9% respectively, which can be used as reforming materials; the 165-240°C jet fuel yields are 8.9%, 14.31% and 18.16% respectively, the smoke points are 28.5 mm, 30.9 mm and 35.5 mm respectively, which can be used as No. 3 jet fuel; the 240-370°C middle distillate oil yields are 44.1%, 41.29% and 35.04% respectively, the BMCI values are 12.0, 9.8 and 8.6 respectively, which can be used as high-quality ethylene materials; the >370°C tail oil fraction yields are 35.0%, 24.0% and 14.8% respectively, the viscosity indexes are 145, 148 and 152 respectively, which can be directly used as feedstocks for producing high-viscosity lubricating oil base oil in an isomerization pour point depressing device.

[0081] In Comparative Example 1, a conventional RN-32V hydrofining catalyst was used as the refining catalyst, and the other catalysts and the process conditions were similar to those of Example 1. As shown in Table 2, the removal of the macromolecular impurities in Comparative Example 1 is difficult, and the temperature of the refining reaction needs to be increased to compensate. The nitrogen content of the refined oil is high, which is 15 μg / g. The conversion rate of the hydrotreating reaction unit in Comparative Example 1 is high, which causes the cracking of the high-viscosity index alkanes, and thus the viscosity index of the >370°C tail oil fraction is low, which is only 138. In addition, the BMCI value of the middle distillate oil is high, which is 13.1, due to the insufficient conversion capacity of the macromolecular impurities in the crude oil.

[0082] Example 4, Example 5, Example 6 and Comparative Example 2

[0083] The column bottom oil feedstock cut from the crude oil was mixed with hydrogen and then sequentially passed through the protection reaction unit, the hydrotreating reaction unit and the hydrocracking reaction unit. The reaction effluent was separated and fractionated to obtain light naphtha, heavy naphtha, jet fuel, middle distillate oil and tail oil fraction. The test process condition parameters and product yield and property data are shown in Table 3.

[0084] Table 3

[0085]

[0086]

[0087] From the data in Table 3, it can be seen that Examples 4, 5 and 6 use the same catalyst scheme as Example 1, except that Examples 4, 5 and 6 achieve the reaction control indicators of the present application under different process conditions. The metal removal rates of Examples 4, 5 and 6 are 93%, 95% and 97%, respectively, the asphaltene removal rates are 96%, 96% and 99%, respectively, the conversion rates of >370°C distillate fractions in the hydrotreating reaction unit are all 12.1%, the nitrogen contents of refined oils are 10 μg / g, the cracking conversion rates are 35.2%, 53.0% and 67.0%, respectively, the corresponding <90°C light naphtha distillate fraction yields are 2.3%, 4.2% and 5.8%, respectively, the BMCI values are 11.3, 10.7 and 9.8, respectively, which can be used as high-quality ethylene feedstock; the 90-165°C heavy naphtha distillate fraction yields are 10.7%, 17.3% and 23.2%, respectively, the aromatic potential contents are 45.6%, 44.6% and 44.1%, respectively, which can be used as reforming feedstock; the 165-240°C jet fuel yields are 9.3%, 13.3% and 16.8%, respectively, the smoke points are 28.0 mm, 29.5 mm and 33.1 mm, respectively, which can be used as No. 3 jet fuel; the 240-370°C middle distillate oil yields are 43.7%, 39.8% and 36.4%, respectively, the BMCI values are 12.3, 10.2 and 9.2, respectively, which can be used as high-quality ethylene feedstock; the >370°C tail oil distillate fraction yields are 34.0%, 25.4% and 17.8%, respectively, the viscosity indexes are 145, 147 and 150, respectively, which can be directly used as feedstock for producing high-viscosity lubricating oil base oil in an isomerization and pour point depressing device.

[0088] Comparative Example 2 uses the same catalyst scheme as Example 4, except that only the high-activity CAT-a hydrocracking catalyst is used as the hydrocracking catalyst. From the data in Table 3, it can be seen that in Comparative Example 2, the conversion rate of >370°C distillate fraction in the hydrotreating reaction unit is 25%, the cracking conversion rate is 80%, and although the viscosity index of the tail oil distillate fraction is 147, which can be used as feedstock for producing lubricating oil base oil in an isomerization and pour point depressing device, the viscosity index and the tail oil distillate fraction yield are both low due to the excessively high conversion rates of the hydrotreating and hydrocracking reaction units, and the process economy is not reasonable.

[0089] Comparative Example 3

[0090] The hydrogenation treatment reaction unit upstream of Comparative Example 3 was packed with a hydrofining catalyst CAT-3, and the hydrogenation treatment reaction unit downstream was packed with a CAT-2 hydrofining catalyst, the proportion of the pore volume of the pores with a pore size >10 nm to the total pore volume in CAT-2 was 44.5% lower than that in CAT-3 (the calculation method was: 100% x (82.34%-57%) / 57%), see Table 4.

[0091] As can be seen from Table 4, Comparative Example 3 also used the same process scheme as Example 1, but the upstream hydrofining catalyst was CAT-3 hydrofining catalyst. Although CAT-3 has a higher load of metal oxides, the conversion performance of macromolecular aromatic and naphthenic molecules in the bottom oil feedstock in the method of this comparative example decreased, and the viscosity index of the product tail oil fraction decreased significantly.

[0092] Comparative Example 4

[0093] The upstream of the hydrocracking reaction unit of Comparative Example 4 was packed with a hydrocracking catalyst CAT-c, and the downstream was packed with a hydrocracking catalyst Cat-b, see Table 4.

[0094] As can be seen from Table 4, Comparative Example 4 used the same process scheme as Example 1, but the product tail oil yield and viscosity index in Comparative Example 4 decreased significantly at a similar conversion rate.

[0095] Table 4

[0096]

[0097]

[0098] In summary, the method of the present application can process crude oil feedstock in a short process and at low cost to directly obtain light naphtha and middle distillate oil that can be used as ethylene material, heavy naphtha that can be used as reforming material, and isomerization and pour point reduction device feed that can be used to produce high viscosity lubricating oil base oil.

[0099] The above describes the preferred embodiments of the present application in detail, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be considered as disclosed by the present application and fall within the protection scope of the present application.

Claims

1. A method for crude oil hydrocracking, characterized in that, The method includes: (1) The crude oil feedstock is introduced into a pre-fractionation tower for separation to obtain the top naphtha fraction, the side-stream jet fuel fraction and the bottom oil fraction; the cut-off point of the top naphtha fraction is 140℃-175℃ and the cut-off point of the side-stream jet fuel fraction is 220℃-280℃. (2) In the presence of hydrogen-rich gas, the bottom oil fraction of the tower is sequentially passed through a protection reaction unit, a hydrogenation reaction unit and a hydrocracking reaction unit for hydrogenation treatment to obtain the reaction effluent; (3) The reaction effluent is fractionated to obtain light naphtha, heavy naphtha, jet fuel, middle distillate and tail oil fraction; In step (2), the protective reaction unit is provided with at least two catalyst beds, each catalyst bed has the same catalyst gradation method, and each catalyst bed is filled with a hydrogenation protection catalyst and a hydrogenation demetallization catalyst. Based on the catalyst bed filling volume of 100%, the filling volume ratio of the hydrogenation protection catalyst and the hydrogenation demetallization catalyst is 80%:20% to 20%:80%. The hydrogenation reaction unit is packed with at least two types of hydrogenation refining catalysts rich in large-pore supports. The K value of the hydrogenation refining catalysts decreases sequentially according to the flow direction of the liquid phase stream. The K value of the upstream hydrogenation refining catalyst is 20%-40% higher than that of the downstream hydrogenation refining catalyst. The K value is the proportion of the pore volume >10 nm in the hydrogenation refining catalyst to the total pore volume. The hydrocracking reaction unit is packed with at least two hydrocracking catalysts containing Y-type molecular sieves. Based on the total weight of the support and the direction of liquid flow, the content of Y-type molecular sieves in the hydrocracking catalyst of the upstream bed is 50% to 200% higher than the content of Y-type molecular sieves in the hydrocracking catalyst of the adjacent downstream bed.

2. The method for crude oil hydrocracking according to claim 1, characterized in that, In step (2), each catalyst bed is provided with a feed inlet. When the pressure drop of the i-th catalyst bed rises to the set value a, the feed inlet of the i-th catalyst bed is cut off and the material from the i-1-th catalyst bed is introduced into the feed inlet of the i+1-th catalyst bed, i≥1, and a is 0.35MPa~0.5MPa.

3. The method for crude oil hydrocracking according to claim 1 or 2, characterized in that, In the protected reaction unit, the hydrogenation protective catalyst comprises a support and an active metal component. The support is alumina, and the active metal component contains at least one Group VIII metal element and at least one Group VIB metal element. The Group VIII metal element is nickel and / or cobalt, and the Group VIB metal element is molybdenum and / or tungsten. Based on the total weight of the hydrogenation protective catalyst, the content of the Group VIII metal element, calculated as oxides, is 0.3 wt%-5 wt%, and the content of the Group VIB metal element is 1 wt%-10 wt%.

4. The method for crude oil hydrocracking according to claim 1 or 2, characterized in that, In the protected reaction unit, the hydrodemetallization catalyst comprises a support and an active metal component. The support is alumina, and the active metal component contains at least one Group VIII metal element and at least one Group VIB metal element. The Group VIII metal element is nickel and / or cobalt, and the Group VIB metal element is molybdenum and / or tungsten. Based on the total weight of the hydrodemetallization catalyst, the content of the Group VIII metal element, calculated as oxides, is 1 wt%-5 wt%, and the content of the Group VIB metal element is 1 wt%-15 wt%.

5. The method for crude oil hydrocracking according to any one of claims 1-4, characterized in that, The conditions of the protective reaction unit are controlled such that the metal removal rate of the protective reaction unit is 95%-100% and the asphalt removal rate is 85%-100%.

6. The method for crude oil hydrocracking according to any one of claims 1-5, characterized in that, The reaction conditions of the protected reaction unit include: a reaction pressure of 8.0 MPa-20.0 MPa, a reaction temperature of 260℃-420℃, and a liquid hourly space velocity of 0.5 h⁻¹. -1 -15h -1 The hydrogen-to-oil volume ratio is 50-600.

7. The method for crude oil hydrocracking according to any one of claims 1-6, characterized in that, In the hydrogenation reaction unit, in the hydrogenation refining catalyst, the macroporous support is an alumina support and / or an alumina-silica support.

8. The method for crude oil hydrocracking according to any one of claims 1-7, characterized in that, In the hydrogenation reaction unit, the hydrogenation refining catalyst further contains Group VIII and Group VIB metal elements, wherein the Group VIII metal element is nickel and / or cobalt, and the Group VIB metal element is molybdenum and / or tungsten; based on the total weight of the hydrogenation refining catalyst, the content of the Group VIII metal element, calculated as oxides, is 1 wt%-15 wt%, and the content of the Group VIB metal element is 5 wt%-40 wt%.

9. The method for crude oil hydrocracking according to any one of claims 1-8, characterized in that, In the hydrotreating reaction unit, the K value of the upstream hydrorefining catalyst is 65%-85%.

10. The method for crude oil hydrocracking according to any one of claims 1-9, characterized in that, In the hydrogenation reaction unit, the macroporous support of the downstream hydrogenation refining catalyst does not contain F and P elements.

11. The method for crude oil hydrocracking according to any one of claims 1-10, characterized in that, The reaction conditions of the hydrogenation treatment reaction unit include: a reaction pressure of 8.0 MPa-20.0 MPa, a reaction temperature of 280℃-400℃, and a liquid hourly space velocity of 0.5 h⁻¹. -1 -6h -1 The hydrogen-to-oil volume ratio is 300-2000.

12. The method for crude oil hydrocracking according to any one of claims 1-11, characterized in that, The nitrogen content of the hydrorefined oil in the bottom oil fraction is less than 20 μg / g. The reaction conditions of the hydrotreating reaction unit are controlled so that the conversion rate of the >370℃ fraction is 6%-18%. Conversion rate of >370℃ fraction = 100% × (mass of >370℃ fraction in the bottom oil feed at the inlet of the protection reaction unit - mass of >370℃ fraction in the product oil obtained in the hydrotreating reaction unit) / mass of >370℃ fraction in the bottom oil feed at the inlet of the protection reaction unit.

13. The method for crude oil hydrocracking according to any one of claims 1-12, characterized in that, Based on the total weight of the carrier and the direction of liquid flow, the content of Y-type molecular sieve in the hydrocracking catalyst of the upstream bed is 50% to 100% higher than the content of Y-type molecular sieve in the hydrocracking catalyst of the adjacent downstream bed.

14. The method for crude oil hydrocracking according to any one of claims 1-13, characterized in that, The hydrocracking catalyst also contains heat-resistant inorganic oxides and active metal components. The heat-resistant inorganic oxides are selected from at least one of silicon oxide, aluminum oxide, and amorphous aluminum silicate. The active metal components contain at least one Group VIII metal element and at least one Group VIB metal element. Based on the total weight of the hydrocracking catalyst, the content of the Group VIB metal element is 15wt%-35wt% and the content of the Group VIII metal element is 2wt%-8wt% based on the oxide content.

15. The method for crude oil hydrocracking according to any one of claims 1-14, characterized in that, In the hydrocracking catalyst in the downstream bed, the content of the Y-type molecular sieve is 1wt%-15wt% based on the total weight of the support, and the balance is the heat-resistant inorganic oxide.

16. The method for crude oil hydrocracking according to any one of claims 1-15, characterized in that, The reaction conditions of the hydrocracking reactor unit include: a reaction pressure of 8.0 MPa-20.0 MPa, a reaction temperature of 290℃-420℃, and a liquid hourly space velocity of 0.3 h⁻¹. -1 -5h -1 The hydrogen-to-oil volume ratio is 300-2000; Preferably, the reaction temperature of the hydrocracking reaction unit is 370℃-410℃.

17. The method for crude oil hydrocracking according to any one of claims 1-16, characterized in that, The conditions are controlled such that the cracking conversion rate of the hydrocracking reaction unit is 35%-74%; The cracking conversion rate = 100% × (mass yield of >370℃ fraction in the bottom oil feed at the inlet of the protection reaction unit - mass yield of >370℃ fraction in the liquid reaction effluent obtained from the hydrocracking reaction unit) / bottom oil feed at the inlet of the protection reaction unit.

18. The method for crude oil hydrocracking according to any one of claims 1-17, characterized in that, The API gravity of the crude oil feedstock is 35-50.

19. The method for crude oil hydrocracking according to any one of claims 1-18, characterized in that, The crude oil feedstock contains Fe element content ≤20μg / g, Ca element content ≤20μg / g, Ni element content ≤10μg / g, V element content ≤10μg / g, residual carbon mass fraction ≤4%, and asphaltene content ≤6000μg / g.

20. The method for crude oil hydrocracking according to claim 19, characterized in that, The method further includes: before entering the pre-fractionation tower, the crude oil feedstock is first desalted and dehydrated, and the salt content of the crude oil feedstock after desalting is less than 2.0 mg / L, and the water content of the crude oil feedstock after dehydration is less than 0.1 wt%.

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