CN110938468A

CN110938468A - Hydrocracking process

Info

Publication number: CN110938468A
Application number: CN201811114272.9A
Authority: CN
Inventors: 崔哲; 吴子明; 王仲义; 孙士可; 彭冲; 曹正凯; 范思强
Original assignee: China Petroleum and Chemical Corp; Sinopec Dalian Research Institute of Petroleum and Petrochemicals
Current assignee: Sinopec Dalian Petrochemical Research Institute Co ltd; China Petroleum and Chemical Corp
Priority date: 2018-09-25
Filing date: 2018-09-25
Publication date: 2020-03-31
Anticipated expiration: 2038-09-25
Also published as: CN110938468B

Abstract

The invention discloses a hydrocracking method, which comprises the following steps of (1) mixing a diesel raw material with hydrogen, firstly feeding the mixture into a hydrofining reactor for desulfurization, denitrification and aromatic saturation, and (2) feeding the effluent obtained in the step (1) into a hydrocracking reactor, wherein the hydrocracking reactor comprises a 1 st to an nth catalyst bed layer along the material direction, n is more than or equal to 3, preferably n is 3 or 4, wherein the 1 st to the nth-1 st catalyst bed layers are filled with a hydrocracking catalyst containing a modified Y molecular sieve, and the nth catalyst bed layer is filled with a hydroisomerization catalyst containing molecular sieves with strong isomerization performance such as β or ZSM and the like.

Description

Hydrocracking process

Technical Field

The invention relates to a hydrocracking method, in particular to a hydrocracking method for producing high-quality clean fuel and improving the low-temperature fluidity of middle distillate oil by using diesel oil as a raw material, particularly straight-run diesel oil.

Background

The hydrocracking technology has the characteristics of strong raw material adaptability, large flexibility of production operation and product scheme, good product quality and the like, can directly convert various heavy inferior feeds into high-quality jet fuel, diesel oil, lubricating oil base stock which are urgently needed by the market and ethylene raw materials prepared by cracking chemical naphtha and tail oil steam, becomes one of the most important heavy oil deep processing technologies in modern oil refining and petrochemical industries, and is increasingly widely applied at home and abroad. With the reduction of the current diesel market demand in China, the reduction of the diesel yield and the increase of the yield of chemical raw materials become important means for improving the economic benefit of refining and chemical enterprises.

The diesel hydrocracking device mainly produces high aromatic hydrocarbon heavy naphtha, 3# jet fuel blending component and high-quality diesel blending component, in the hydrocracking process, macromolecule polycyclic aromatic hydrocarbon has high polarity and is more easily adsorbed on the surface of a catalyst to generate a cracking reaction to generate monocyclic aromatic hydrocarbon, the monocyclic aromatic hydrocarbon is difficult to generate aromatic hydrocarbon saturation and ring opening reaction, the unconverted monocyclic aromatic hydrocarbon is enriched in aviation kerosene and diesel oil fractions to influence the combustibility of aviation kerosene and diesel oil products, and particularly when the properties of raw materials are poor and the operation conditions are harsh, the influence on the combustibility of aviation kerosene and diesel oil products is more obvious.

CN200610008413.X discloses a combined hydrocracking method, which comprises the steps of firstly carrying out hydrotreating on poor quality catalytic cracking diesel, mixing a cracking product with VGO and other raw materials, entering a second hydrocracking reaction zone, and then separating various light products and hydrogenated tail oil.

CN200510068180.8 discloses a hydrocracking method for producing chemical raw materials to the maximum, in which heated raw oil and hydrogen enter a first reaction zone to be sequentially contacted with a hydrofining catalyst and a hydrocracking catalyst, the reaction material flow is subjected to oil-gas separation, the obtained hydrogen-rich gas is compressed and recycled, the liquid is fractionated to obtain light naphtha, heavy naphtha, diesel fraction and tail oil fraction, wherein the diesel fraction is pressurized and then mixed with recycle hydrogen and then contacted with the hydrocracking catalyst, and the reaction material flow of the step and the reaction material flow of the previous step are mixed and enter a separation and fractionation system.

CN201110284518.9 discloses a hydrocracking method for selectively increasing yield of aviation kerosene, which comprises the steps of mixing raw oil with hydrogen, then carrying out hydrofining reaction and hydrocracking reaction in turn, cooling and separating reaction effluent, returning 10-100% of heavy diesel oil fraction obtained to a raw material tank for continuous reaction, wherein the aromatic hydrocarbon and naphthenic hydrocarbon content of the fraction are lower, and the fraction is suitable for selectively increasing yield of aviation kerosene fraction. Although the method can achieve the effect of increasing the yield of the aviation kerosene, only a small part of the circulating oil undergoes cracking reaction, and the effect of increasing the yield of chemical raw materials is not obvious.

CN201210440422.1 discloses a hydrogenation method combining hydrocracking and hydrogenation dearomatization, which carries out hydrofining on poor-quality catalytic cracking diesel and hydrogen in a gas-liquid countercurrent mode; carrying out hydrogenation dearomatization reaction on refined oil in the presence of a noble metal catalyst; carrying out hydrocracking pretreatment reaction on the wax oil and hydrogen, and carrying out hydrocracking reaction after mixing the hydrocracking pretreatment effluent and the hydrodearomatization effluent; separating and fractionating the hydrocracking effluent to obtain different fraction products; the cracking tail oil is circulated to the hydrogenation dearomatization reactor, and the method can solve the problem of limited catalytic diesel oil treatment capacity, greatly improve the light oil yield and improve the product quality, but has high equipment investment and complex device operation.

CN200610008418.2 discloses a two-stage hydrocracking method, which adopts a two-stage hydrocracking method to treat poor quality catalytic diesel, especially poor quality catalytic diesel obtained from catalytic hydrogen transfer process. The catalytic diesel has extremely poor properties, the density at 20 ℃ is more than 0.90g/ml, the aromatic hydrocarbon is more than 60wt%, and the cetane number is less than 30. The poor quality catalytic cracking diesel oil and the heavy cracking raw material are mixed and subjected to hydrogenation treatment, impurities such as sulfur, nitrogen and the like in the generated oil are removed, separation is carried out, and then hydrocracking is carried out.

CN201310540392.6 discloses a low energy consumption hydrocracking method for producing high quality jet feedstock. Mixing raw oil with hydrogen, performing heat exchange twice, and sequentially passing through a hydrofining reaction zone and a hydrocracking reaction zone; the hydrocracking reaction zone comprises at least two hydrocracking catalysts, wherein the upstream is filled with a catalyst I, and the downstream is filled with a catalyst II; wherein the catalyst I contains 15-50 wt% of modified Y molecular sieve, the catalyst II contains 3-30 wt% of modified Y molecular sieve, and the content of the modified Y molecular sieve in the catalyst I is 10-25 percent higher than that of the catalyst II. The method organically combines a high-temperature high-pressure countercurrent heat transfer technology with a hydrocracking catalyst grading technology, comprehensively utilizes hydrocracking reaction heat, not only fully exerts the characteristics of two different types of hydrocracking catalysts, improves the quality of a target product while maintaining the selectivity of the catalysts, but also reduces the engineering investment and the operation energy consumption.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a hydrocracking method. The method takes diesel oil as a raw material, and increases the yield of heavy naphtha with high aromatic hydrocarbon potential and improves the low-temperature fluidity of aviation kerosene and diesel oil products by reasonably combining hydrocracking catalysts with different functions.

The hydrocracking method comprises the following steps:

(1) mixing a diesel raw material and hydrogen, and firstly entering a hydrofining reactor for desulfurization, denitrification and aromatic saturation reaction;

(2) and (2) enabling the effluent in the step (1) to enter a hydrocracking reactor, wherein the hydrocracking reactor comprises a 1 st to an nth catalyst bed layer along the material direction, n is more than or equal to 3, preferably n is 3 or 4, wherein the 1 st to the nth-1 st catalyst bed layers are filled with a hydrocracking catalyst containing a modified Y molecular sieve, and the nth catalyst bed layer is filled with a hydroisomerization catalyst containing molecular sieves with strong isomerization performance, such as β and/or ZSM series.

Wherein the percentage content C of the modified Y molecular sieve in the hydrocracking catalyst of each bed layer₁~C_n-1(based on the total amount of catalyst) has the following relationship: c_n-2/C_n-1Less than 1, wherein the percentage content C of β and/or ZSM series molecular sieves in the hydrocracking catalyst of the last bed is_n≤C₁~C_n-1Minimum value of (1);

average pore diameter D of hydrocracking catalyst of each bed layer₁~D_nHas the following relationship: d₁/D₂＞1，D_n-1/ D_n< 1 wherein D₁≤D₂~D_nMaximum value of (1), D_n≥D₁~D_n-1Maximum value of (1);

percentage active metal content M of hydrocracking catalyst of each bed layer₁~M_n(based on the total amount of catalyst) has the following relationship: m₁/M₂＞1，M_n-1/M_n< 1, wherein M₁≥M₂~M_nMinimum value of (1), M_n≥M₁~M_nMaximum value of (1);

wherein the percentage content of the modified Y molecular sieve in the hydrocracking catalyst of each bed layer and the percentage content of active metal have the following relationship: c is more than or equal to 0.1₁/M₁~C_n/M_nAny ratio is less than or equal to 3;

(3) and separating the effluent of the hydrocracking reactor into a gas phase and a liquid phase, recycling the gas phase, and introducing the liquid phase into a fractionating tower for fractionating to obtain naphtha, aviation kerosene and diesel oil.

In the process according to the invention, the packing volume V of the catalyst in the beds in the direction of flow₁~V_nHas the following relationship: v is more than 0.1₂/V₁＜5，1＜V_n-1/V_n< 10, wherein V_n-1＞V₁~V_nMinimum value of (1).

In the method, the diesel raw material is one or more of straight-run diesel, coking diesel and catalytic diesel; the density of the catalytic diesel oil is generally 0.92-0.96 g/cm³Wherein the final distillation point is generally 350-450 ℃, preferably 390-430 ℃; aromatic hydrocarbon content of 60-80%, cetane number of 15-25, contents of impurities such as sulfur and nitrogen, S content of more than 0.1%, and N contentThe content is generally greater than 500 ppm.

In the method, the hydrocracking catalyst can be in the shape of a strip or a ball, if a strip catalyst is selected, the granularity of the catalyst is 3-15 mm, if a ball catalyst is selected, the granularity of the catalyst is 1-8 mm, the granularity of the catalyst is P, and the granularity of the catalyst is P₁~P_nHas the following relationship: p₁/P₂＞1，P_n-1/ P_n< 1 wherein P₁≤P₂~P_nMaximum value of (1), P_n≥P₁~P_n-1Maximum value of (2).

In the method, a hydrofining reactor is filled with a hydrofining catalyst which is conventional in the field, and the hydrofining catalyst comprises a carrier and hydrogenation active metal; wherein the carrier is inorganic refractory oxide, generally selected from one or more of alumina, amorphous silicon-aluminum, silicon dioxide or titanium oxide, etc.; the hydrogenation active metal comprises metal components of VIB and/or VIII groups, wherein the VIB group is selected from tungsten and/or molybdenum and calculated by oxide is 10-35%, preferably 15-30%, and the VIII group is selected from nickel and/or cobalt and calculated by oxide is 1-7%, preferably 1.5-6%. The carrier is inorganic refractory oxide, and is generally selected from alumina, amorphous silica-alumina, silica, titanium oxide and the like. The hydrofining catalyst can be selected from conventional hydrocracking pretreatment catalysts, wherein the conventional hydrocracking pretreatment catalysts can be selected from various existing commercial catalysts, such as hydrotreating catalysts developed and developed by the Fushu petrochemical industry research institute (FRIPP), such as 3936, 3996, FF-16, FF-26, FF-36 and FF-46; it can also be prepared according to the common knowledge in the field, if necessary.

The preferred hydrofining reactor of the present invention is packed as follows: the hydrofining reactor at least comprises two hydrofining catalyst beds, wherein the upper part of each hydrofining catalyst bed is filled with a hydrofining catalyst A, the lower part of each hydrofining catalyst bed is filled with a hydrofining catalyst B, the hydrofining catalyst A is a non-roasted hydrofining catalyst and is loaded with an organic compound while being loaded with active metal, and the hydrofining catalyst B is a roasted catalyst; in the method, the granularity of the hydrofining catalyst A is higher than that of the hydrofining catalyst B, and the granularity of the hydrofining catalyst A is 1.3-3 times that of the hydrofining catalyst B. The hydrofining catalysts A and B can be in the shape of a strip or a ball, for example, a strip catalyst is selected, the granularity of the catalyst A is 5-10 mm, for example, a ball catalyst is selected, and the granularity of the catalyst A is 3-6 mm. The aperture of the hydrofining catalyst A is 2-8 nm, preferably 3-6 nm, and the aperture of the hydrofining catalyst B is 1.2-4 times of that of the hydrofining catalyst A.

The active component in the catalyst is one or more of W, Mo, Ni and Co, the active component is in an oxidation state, and the content of the active component is generally 15-45% by weight of oxide. The oxidation state catalyst is selected to be subjected to conventional vulcanization treatment before use, so that the hydrogenation active component is converted into a vulcanization state. The catalyst A is subjected to high-temperature roasting after the carrier is formed, roasting is carried out for 0.5-20 hours at the temperature of 300-750 ℃, and then an active metal component and an organic auxiliary agent are impregnated, wherein the organic compound comprises but is not limited to at least one of sulfoxide, the hydrorefining catalyst is obtained without roasting after drying, the drying temperature is 70-290 ℃, and the drying time is 0.5-20 hours; the commercially available catalysts comprise FF-46 and FF-56 which are developed by the research and development institute of petrochemical engineering (FRIPP), and can also be prepared by the method of CN101491766A and the like; the catalyst A can not be dried at high temperature in the start-up process, and the temperature of a catalyst bed layer can not be higher than 160 ℃ before start-up oil is introduced. The catalyst B is roasted at high temperature after the carrier is molded, the catalyst B is roasted at the temperature of 300-750 ℃ for 0.5-20 hours, then an active metal component and an organic auxiliary agent are impregnated, and the hydrogenation refining catalyst is obtained by roasting, wherein the roasting temperature is 300-750 ℃, the roasting time is 0.5-20 hours, the commercially available catalysts comprise hydrogenation catalysts such as 3926, 3936, CH-20, FF-14, FF-18, FF-24, FF-26, FF-36, FH-98, FH-UDS, FZC-41 and the like developed by the research and development institute of petrochemical industry (FRIPP), hydrogenation catalysts such as HR-416, HR-448 and the like of IFP company, hydrogenation catalysts such as ICR174, ICR178, ICR 179 and the like of CLG company, hydrogenation catalysts such as HC-P, HC-K UF-210/220, TK-525, TK-555, TK-557 and the like of Topsor company, KF-752, KF-840, KF-848, KF-901, KF-907 and the like hydrogenation catalysts available from AKZO corporation.

In the method, the filling volume of the hydrofining catalyst A in the first hydrofining catalyst bed layer accounts for 1-80 v%, preferably 10-50 v%, of the first hydrofining catalyst bed layer; the hydrofining catalyst B filled in the second hydrofining catalyst bed layer is 5-60% higher than the hydrofining catalyst B filled in the first hydrofining catalyst bed layer, and the preferred range is 10-50%.

In the prior art, more than ten theoretical models are proposed in turn aiming at the structure of the active phase of the hydrotreating catalyst, wherein the Co-Mo-S model proposed by Tops ø e and the like is the model which has the most influence at present, the Co-Mo-S active phase is divided into a single-layer (called I type Co-Mo-S) and a multi-layer (called II type Co-Mo-S), the I type Co-Mo-S is connected with a carrier through a Mo-O-Al bond and is a low-sulfur coordinated Co-Mo-S active phase, and the interaction of Mo and Al is strong, so that MoS is influenced₂The edge, corner Co electronic states, result in low intrinsic (intrinsic) activity per active center. The type II Co-Mo-S has lower interaction with the carrier, so the type II Co-Mo-S is easier to completely vulcanize and is in a stacked MoS₂The structure, a highly sulfur coordinated Co-Mo-S active phase, is usually stacked (laminated) together from larger sheets, not attached to a support, and the intrinsic activity of each active center of the type II active phase is high. Pure Al₂O₃By Mo-O-Al connection, MoS₂The single-layer dispersion is good, the single-layer dispersion is an I-type active phase, and the P, B, Si auxiliary agent is added, so that Mo-O-Al connection can be weakened, and a mixed active phase of the I type and the II type can be generated. The II type active phase catalyst has better hydrogenation activity, and is particularly characterized in that the effects of hydrodenitrogenation and aromatic hydrocarbon saturation are better at a lower flat reaction temperature; however, the catalyst is not calcined at high temperature in the preparation process, so that the high-temperature stability of the catalyst is poor, and therefore, when heavy and poor-quality raw materials are processed, a high reaction temperature is required, and the catalytic activity of the catalyst in a high-temperature reaction zone of a reactor cannot be effectively exerted. The invention fills II type active phase hydrogenation catalyst at the upper part (i.e. low temperature reaction zone) of each catalyst bed layer, and fills common I type active phase hydrogenation catalyst at the lower part (i.e. high temperature reaction zone), thereby fully playing the characteristic of good low temperature activity of II type active phase hydrogenation catalyst, improving hydrogenation saturation effect and simultaneously being capable of improving hydrogenation saturation effectGenerate larger reaction heat, promote the exertion of the activity of the common I-type active phase hydrogenation catalyst, better improve the aromatic saturation and denitrification depth of the hydrofining reaction and improve the product quality.

In the process of the present invention, the reaction conditions in the hydrofining reactor are generally: the reaction pressure is 5.0-35.0 MPa, preferably 6.0-19.0 MPa; the average reaction temperature is 200-480 ℃, and preferably 270-450 ℃; the volume space velocity is 0.1-15.0 h^-1Preferably 0.2 to 3.0 hours^-1(ii) a The volume ratio of hydrogen to oil is 100: 1-2500: 1, preferably 400: 1-2000: 1. the inlet of each bed layer of the hydrofining reactor is provided with T_nIs represented by, and n is ≧ 2, wherein T_n≥T_n-1，T_n-T_n-1≤20℃。

In the method of the invention, the hydrocracking operation conditions comprise: the reaction pressure is 5.0-35.0 MPa, preferably 6.0-19.0 MPa; the average reaction temperature is 200-480 ℃, preferably 270-450 ℃; the volume space velocity is 0.1-15.0 h^-1Preferably 0.2 to 3.0 hours^-1(ii) a The volume ratio of hydrogen to oil is 100: 1-2500: 1, preferably 400: 1-2000: 1.

in the method, the hydrocracking catalyst comprises an active metal component and a carrier, wherein the active metal component is selected from one or more of group VIII and/or group VIB metals, the group VIII metal is Co and/or Ni generally, the group VIB metal is Mo and/or W generally, and the carrier is amorphous silicon-aluminum and/or aluminum oxide. Hydrocracking catalysts generally comprise a cracking component, a hydrogenation component and a binder. Such as any suitable hydrocracking catalyst including those known in the art. The cracking component typically comprises amorphous silica-alumina and/or molecular sieves, typically molecular sieves such as Y-type or USY-type molecular sieves. The binder is typically alumina or silica. The hydrogenation component is a metal, a metal oxide or a metal sulfide of a metal in a VI group, a VII group or a VIII group, and more preferably one or more of iron, chromium, molybdenum, tungsten, cobalt, nickel or sulfides or oxides thereof. The hydrogenation component content is usually 5 to 40wt% based on the weight of the catalyst. Specifically, the existing hydrocracking catalyst may be selected, or a specific hydrocracking catalyst may be prepared as required. Commercial hydrocracking catalysts are mainly: HC-12, HC-14, HC-24, HC-39, etc. by UOP, 3905, 3955, FC-12, FC-16, FC-24, FC-32, 3971, 3976, FC-26, FC-28, etc. by FRIPP, and ICR126, ICR210, etc. by CHEVRON. The commercial hydrogenation modification catalyst can be FC-14 catalyst developed by the Fushun petrochemical research institute (FRIPP), SDD-800 catalyst developed by the American Shell company, and the like.

Taking the example of three catalyst beds: the hydrocracking catalyst containing the modified Y molecular sieve in the first catalyst bed layer has the following properties: content C of modified Y molecular sieve₁5wt% to 30wt%, preferably 15wt% to 25wt%, average pore diameter D of the catalyst₁5-20nm, preferably 7-11 nm, and the active metal content M in the catalyst₁10wt% to 40wt%, preferably 20wt% to 30 wt%; wherein 0.6 is less than or equal to C₁/M₁Less than or equal to 1. If a catalyst in the form of a strip is used, the particle size P of the catalyst₁5-12 mm, preferably 6-10 mm, if a spherical catalyst is selected, the particle size P of the catalyst₁2 to 7mm, preferably 3 to 5 mm.

In the second catalyst bed, the average pore diameter D of the catalyst₂Ratio D₁The content of the modified Y molecular sieve is 0.5-5 nm, preferably 1-2 nm₂Ratio C₁10-30 wt% higher, and the active metal content M in the catalyst₂Ratio M₁5-10 wt% lower; if a catalyst in the form of a strip is used, the particle size P of the catalyst₂2-8 mm, preferably 3-6 mm, if a spherical catalyst is selected, the particle size P of the catalyst₂1-5 mm, preferably 2-4 mm; wherein 1.5 is less than or equal to C₂/M₂≤2。

In the third catalyst bed, the average pore diameter D of the catalyst₃Ratio D₂A high molecular sieve content of 1-7 nm, preferably 2-4 nm, β or ZSM molecular sieve C₃Ratio C₂30-50 wt% lower, active metal content M₃Ratio M₂10-20 wt% higher; if a catalyst in the form of a strip is used, the particle size P of the catalyst₃6-15 mm, preferably 8-12 mm, if a spherical catalyst is selected, the particle size P of the catalyst₁3-8 mm, preferably 4-6 mm; wherein 0.1 is less than or equal to C₃/M₃≤0.6。

Filling of three catalyst bedsVolume is respectively V₁、V₂And V₃Wherein 0.5<V₁/ V₂<2, 1<V₂/ V₃<5。

In the prior art, a diesel hydrocracking device mainly produces high aromatic hydrocarbon heavy naphtha, a 3# jet fuel blending component and a high-quality diesel blending component, in the hydrocracking process, macromolecule polycyclic aromatic hydrocarbon has high polarity and is more easily adsorbed on the surface of a catalyst to generate a cracking reaction to generate monocyclic aromatic hydrocarbon, the monocyclic aromatic hydrocarbon is difficult to generate aromatic hydrocarbon saturation and ring-opening reaction, the unconverted monocyclic aromatic hydrocarbon is enriched in aviation kerosene and diesel oil fractions to influence the combustibility of aviation kerosene and diesel oil products, and particularly when the properties of raw materials are poor and the operation conditions are harsh, the influence on the combustibility of aviation kerosene and diesel oil products is more obvious. The hydrocracking catalyst with larger aperture and moderate cracking activity is filled in the upper bed layer of the hydrocracking reactor, the polycyclic aromatic hydrocarbon in the raw material is firstly subjected to hydrogenation saturation and ring-opening reaction to be converted into monocyclic aromatic hydrocarbon with side chains, because the monocyclic aromatic hydrocarbon is difficult to convert, the average aperture of the catalyst is reduced, the reaction that macromolecular polycyclic aromatic hydrocarbon enters into a catalyst pore passage and preferentially reacts can be reduced, the influence of competitive adsorption on the cracking reaction of the monocyclic aromatic hydrocarbon can be reduced, the retention time of reactants in the catalyst can be increased, the content of a molecular sieve of the small-aperture catalyst is increased, the side chain of the monocyclic aromatic hydrocarbon which is difficult to convert can be subjected to the cracking reaction of naphtha to generate monocyclic aromatic hydrocarbon and paraffin, thus the aromatic hydrocarbon in the aviation kerosene and diesel oil component can be effectively converted into heavy petroleum naphtha component, and the paraffin hydrocarbon can be retained in the aviation kerosene and diesel oil component, the catalyst with larger aperture and strong hydroisomerization is filled at the bottom of the reactor, so that the low-temperature fluidity of the middle distillate oil can be improved, the occurrence of secondary cracking reaction is reduced, and the yield of low value-added products such as liquefied gas, dry gas and the like is reduced, thereby increasing the yield of high aromatic hydrocarbon heavy naphtha, improving the quality of aviation kerosene and diesel oil products, reducing the yield of light hydrocarbon, and effectively improving the economic benefit of the device.

Detailed Description

The technical features of the process of the present invention are further described by way of examples, which are not intended to limit the invention. In the examples and comparative examples,% is the mass percentage unless otherwise specified. Wherein the hydrofining catalyst is a commercially available FF-56 catalyst (catalyst A), a FF-36 catalyst (catalyst B), a hydrocracking catalyst I, a hydrocracking catalyst II, a hydrocracking catalyst III and a hydrocracking catalyst IV, and the properties are shown in Table 1. The properties of the feed oil 1 are shown in Table 2, and the properties of the feed oil 2 are shown in Table 3.

Table 1 main physicochemical properties of the catalyst.

Table 2 main properties of feed oil 1.

Table 3 main properties of feed oil 2.

Example 1

Raw oil 1 is used as raw material, 2 catalyst bed layers are arranged in a hydrofining reactor, 3 catalyst bed layers are arranged in a hydrocracking reactor, and catalysts are sequentially filled in the material flow direction

Catalyst, and process for producing the same

And catalyst III, the catalyst loading volume ratio is 1:1: 1. Specific hydrogenation conditions, product distribution and properties are shown in tables 4 and 5.

Example 2

As in example 1, 2 catalyst beds were installed in the hydrofinishing reactor, except that the catalyst packing volume ratio was 2: 1: 1. specific hydrogenation conditions, product distribution and properties are shown in tables 4 and 5.

Example 3

As in example 1, 2 catalyst beds were installed in the hydrofinishing reactor, except that the catalyst loading volume ratio was 1: 2: 1. specific hydrogenation conditions, product distribution and properties are shown in tables 4 and 5.

Example 4

Raw oil 1 is taken as a raw material, 2 catalyst bed layers are arranged in a hydrofining reactor, wherein a hydrocracking reactor is provided with 4 catalyst bed layers, and catalysts are sequentially filled in the material flow direction

Catalyst, and process for producing the same

And catalyst III, catalyst loading volume ratio 1:1: 2: 1. specific hydrogenation conditions, product distribution and properties are shown in tables 4 and 5.

Example 5

Raw oil 1 is taken as a raw material, 1 catalyst bed layer is arranged in a hydrofining reactor, hydrofining catalyst A is filled in the catalyst bed layer, 3 catalyst bed layers are arranged in a hydrocracking reactor, and catalysts are sequentially filled in the hydrocracking reactor along the material flow direction

Catalyst, and process for producing the same

Example 6

The same procedure as in example 5 was repeated, except that the hydrofinishing reactor was charged with the catalyst B.

Comparative example 1

Raw oil 1 is used as raw material, and the interior of hydrofining reactor is filled with catalyst A, in which the hydrocracking reactor is equipped with 1 catalytic reactorCatalyst bed layer filled with catalyst

。

Comparative example 2

Raw oil 1 is used as raw material, a hydrofining reactor is filled with a catalyst B, a hydrocracking reactor is provided with 2 catalyst beds, and the catalysts are sequentially filled along the material flow direction

And a catalyst

The catalyst loading volume ratio is 1: 1.

comparative example 3

Raw oil 1 is used as a raw material, a first bed layer of a hydrofining reactor is filled with a catalyst A, a second bed layer of the hydrofining reactor is filled with a catalyst B, a hydrocracking reactor is provided with 2 catalyst bed layers, and catalysts I are sequentially filled along the material flow direction

And catalyst I

The catalyst loading volume ratio is 1: 1.

table 4 main process conditions and product distribution.

Table 4 (next) main process conditions and product distribution.

Table 5 product key properties.

Table 5 (next) main product properties.

Example 7

Raw oil 2 is used as raw material, 2 catalyst bed layers are arranged in a hydrofining reactor, 3 catalyst bed layers are arranged in a hydrocracking reactor, and catalysts are sequentially filled in the material flow direction

Catalyst, and process for producing the same

And a catalyst III, the catalyst loading volume ratio being 1: 2: 1. the process conditions, product distribution and properties are shown in tables 6 and 7.

Example 8

Catalyst, and process for producing the same

Comparative example 4

Raw oil 2 is used as raw material, a hydrocracking reactor is provided with 2 catalyst beds, and catalysts are sequentially filled along the material flow direction

And a catalyst

The catalyst loading volume ratio is 1: 1. the process conditions, product distribution and properties are shown in tables 6 and 7.

TABLE 6 Main Process conditions and product distribution

TABLE 7 Main Properties of the product

It can be seen from the examples and comparative examples that the diesel fuel feedstock can be used to produce high quality catalytic reforming feedstock, 3# jet fuel blending component and high quality diesel blending component by the present technology, and the diesel component can also be used as steam cracking to ethylene feedstock, with low equipment investment cost and simple operation.

Claims

1. A hydrocracking method is characterized by comprising the following steps of (1) mixing a diesel raw material with hydrogen, feeding the mixture into a hydrofining reactor for desulfurization, denitrification and aromatic saturation, and (2) feeding the effluent obtained in the step (1) into a hydrocracking reactor, wherein the hydrocracking reactor comprises a 1 st to an nth catalyst bed layer along the material direction, n is more than or equal to 3, preferably n is 3 or 4, the 1 st to the nth-1 catalyst bed layer is filled with a hydrocracking catalyst containing a modified Y molecular sieve, the nth catalyst bed layer is filled with a hydroisomerization catalyst containing β and/or ZSM series molecular sieves, and (3) separating the effluent of the hydrocracking reactor into a gas phase and a liquid phase, recycling the gas phase, feeding the liquid phase into a fractionating tower, and fractionating to obtain naphtha, aviation kerosene and diesel oil;

wherein the percentage content C of the modified Y molecular sieve in the hydrocracking catalyst of each bed layer₁~C_n-1The catalyst has the following relation based on the total amount of the catalyst: c_n-2/C_n-1Less than 1, wherein the percentage content C of β and/or ZSM series molecular sieves in the hydrocracking catalyst of the last bed is_n≤C₁~C_n-1Minimum value of (1); average pore diameter D of hydrocracking catalyst of each bed layer₁~D_nHas the following relationship: d₁/D₂＞1，D_n-1/ D_n＜1，Wherein D₁≤D₂~D_nMaximum value of (1), D_n≥D₁~D_n-1Maximum value of (1); percentage active metal content M of hydrocracking catalyst of each bed layer₁~M_nThe catalyst has the following relation based on the total amount of the catalyst: m₁/M₂＞1，M_n-1/M_n< 1, wherein M₁≥M₂~M_nMinimum value of (1), M_n≥M₁~M_nMaximum value of (2).

2. The method of claim 1, wherein: wherein the percentage content of the modified Y molecular sieve in the hydrocracking catalyst of each bed layer and the percentage content of active metal have the following relationship: any ratio of C1/M1-Cn/Mn is not more than 0.1 and not more than 3.

3. The method of claim 1, wherein: the filling volumes V1-Vn of the catalysts in each bed layer along the material flow direction have the following relations: 0.1 & lt V2/V1 & lt 5, 1 & lt Vn-1/Vn & lt 10, wherein Vn-1 & gt is the minimum value in V1-Vn.

4. The method of claim 1, wherein: the diesel raw material is one or more of straight-run diesel, coking diesel and catalytic diesel.

5. The method of claim 1, wherein: the hydrofining reactor is filled in the following way: the hydrofining reactor at least comprises two hydrofining catalyst beds, wherein the upper part of each hydrofining catalyst bed is filled with a hydrofining catalyst A, the lower part of each hydrofining catalyst bed is filled with a hydrofining catalyst B, the hydrofining catalyst A is a non-roasted hydrofining catalyst and is loaded with an organic compound while being loaded with active metal, and the hydrofining catalyst B is a roasted catalyst; in the method, the granularity of the hydrofining catalyst A is higher than that of the hydrofining catalyst B, and the granularity of the hydrofining catalyst A is 1.3-3 times that of the hydrofining catalyst B.

6. The method of claim 5, wherein: the aperture of the hydrofining catalyst A is 2-8 nm, and the aperture of the hydrofining catalyst B is 1.2-4 times of the aperture of the hydrofining catalyst A.

7. The method of claim 5, wherein: the catalyst A is selected from FF-46 and FF-56 which are developed by the comforting petrochemical research institute, or is prepared by the method described in CN 101491766A; the catalyst A can not be dried at high temperature in the start-up process, and the temperature of a catalyst bed layer can not be higher than 160 ℃ before start-up oil is introduced; catalyst B is selected from one or more of the following catalysts: 3926, 3936, CH-20, FF-14, FF-18, FF-24, FF-26, FF-36, FH-98, FH-UDS or FZC-41 hydrogenation catalysts developed by the research institute of petrochemical engineering, HR-416 and HR-448 hydrogenation catalysts of IFP company, ICR174, ICR178 and ICR 179 hydrogenation catalysts of CLG company, HC-P, HC-K UF-210/220 of UOP company, TK-525, TK-555 and TK-557 hydrogenation catalysts of Topsor company, KF-752, KF-840, KF-848, KF-901 and KF-907 hydrogenation catalysts of AKZO company.

8. The method of claim 5, wherein: the filling volume of the hydrofining catalyst A in the first hydrofining catalyst bed layer accounts for 1-80 v%, preferably 10-50 v%, of the first hydrofining catalyst bed layer; the hydrofining catalyst B filled in the second hydrofining catalyst bed layer is 5-60% higher than the hydrofining catalyst B filled in the first hydrofining catalyst bed layer, and the preferred range is 10-50%.

9. The method according to claim 1 or 5, characterized in that: the reaction conditions in the hydrofinishing reactor are generally: the reaction pressure is 5.0-35.0 MPa, the average reaction temperature is 200-480 ℃, and the volume space velocity is 0.1-15.0 h^-1The volume ratio of hydrogen to oil is 100: 1-2500: 1.

10. the method of claim 5, wherein: the inlet of each bed layer of the hydrofining reactor is represented by Tn, wherein n is more than or equal to 2, Tn is more than or equal to Tn-1, and Tn-Tn-1 is less than or equal to 20 ℃.

11. The method of claim 1, wherein: hydrocracking operating conditions: the reaction pressure is 5.0-35.0 MPa, the average reaction temperature is 200-480 ℃, and the volume space velocity is 0.1-15.0 h^-1The volume ratio of hydrogen to oil is 100: 1-2500: 1.

12. the method of claim 1, wherein: the hydrocracking catalyst comprises an active metal component and a carrier, wherein the active metal component is selected from one or more of VIII group and/or VIB group metals; wherein the VIII group metal is Co and/or Ni, the VIB group metal is Mo and/or W, and the carrier is amorphous silicon aluminum and/or alumina; one or more commercial hydrocracking catalysts selected from the group consisting of: HC-12, HC-14, HC-24, HC-39 and FRIPP 3905, 3955, FC-12, FC-16, FC-24, FC-32, 3971, 3976, FC-26, FC-28 from UOP, ICR126, ICR210 from CHEVRON, FC-14 catalyst developed by the Dow petrochemical institute, SDD-800 catalyst from Shell.

13. The method of claim 1, wherein three catalyst beds are arranged in a hydrocracking reactor, the hydrocracking catalyst containing the modified Y molecular sieve in the first catalyst bed has the following properties that the content of the modified Y molecular sieve C1 is 5-30 wt%, the average pore diameter D1 of the catalyst is 5-20nm, the content of active metal M1 in the catalyst is 10-40 wt%, wherein 0.6-30 wt% of the modified Y molecular sieve C1/M1 is less than or equal to 1, the average pore diameter D2 of the catalyst is 0.5-5 nm lower than D1 in the second catalyst bed, the content of the modified Y molecular sieve C2 is 10-30 wt% higher than C1, the content of the active metal M8 in the catalyst is 5-10 wt% lower than M1, wherein 1.5-3/M2/M2 is less than 2, the average pore diameter D3 of the catalyst in the third catalyst bed is 1-3 nm higher than D2, the content of the active metal ZSM 4642 and/M3 are 0-50 wt% higher than M465 wt% of the activity of the catalyst is 0-20 wt% of the catalyst 465-5 wt% higher than M465 wt% of the C465 wt% of the third catalyst bed, wherein the activity of the catalyst is 1-3 wt.

14. The method of claim 13, wherein: the packing volumes of the three catalyst beds are V1, V2 and V3 respectively, wherein 0.5< V1/V2 <2, 1< V2/V3 < 5.