CN112812846B

CN112812846B - Hydroconversion process for high wax content feedstock

Info

Publication number: CN112812846B
Application number: CN201911128807.2A
Authority: CN
Inventors: 王从新; 田志坚; 曲炜; 马怀军; 潘振栋; 王冬娥; 李鹏; 王琳
Original assignee: Dalian Institute of Chemical Physics of CAS
Current assignee: Dalian Institute of Chemical Physics of CAS
Priority date: 2019-11-18
Filing date: 2019-11-18
Publication date: 2022-05-06
Anticipated expiration: 2039-11-18
Also published as: CN112812846A

Abstract

The invention relates to a method for hydro-conversion of a high-wax content raw material, which comprises the following steps: the high wax content raw material firstly enters a hydrogenation pretreatment reaction zone to complete the hydrogenation saturation, the hydrogenation desulfurization, the hydrogenation denitrification and the hydrogenation deoxidation of non-alkane components in the raw material; the obtained hydrogenation pretreatment oil enters a hydroisomerization reaction zone, and the hydroisomerization of the hydrogenation pretreatment oil is completed on a specific combined hydroisomerization catalyst; the obtained hydrogenation isomeric oil enters a hydrogenation refining reaction zone for further treatment to obtain a crude product; the crude product is fractionated by an atmospheric/vacuum tower to obtain base oil, diesel oil, gasoline and other products. Compared with the prior art, the method can obtain the base oil with higher yield, low pour point and high viscosity index, and has simple process and lower energy consumption.

Description

Hydroconversion process for high wax content feedstock

Technical Field

The invention relates to a method for hydro-conversion of a high-wax-content raw material, in particular to a method for producing a base oil serving as a main product by taking Fischer-Tropsch synthesis wax, vacuum distillate oil, propane deasphalted oil, hydrocracking tail oil, cerate, wax oil and the like as raw materials through hydro-conversion.

Background

With the increasing trend of crude oil heaviness and deterioration and the stricter environmental regulations, the performance requirements of the finished oil are higher and higher. Under the background, the lifting speed of the standard of the lubricating oil is also increased, the base oil of the type I produced by adopting the traditional process can not meet the current use requirement, the advanced production process of the base oil of the lubricating oil is developed, the base oil of the type II, the type III and the natural gas synthetic oil is produced, the energy expansion and the upgrade of the production of the base oil of the lubricating oil can be realized, and the requirement of a consumer is met.

The traditional lubricant base oil production mainly adopts three old sets of processes (solvent refining, solvent dewaxing and clay refining) to remove non-ideal components (polycyclic aromatic hydrocarbon, polar substances and the like) in oil by a physical separation mode and retain hydrocarbon components with high viscosity index and low pour point, thereby preparing qualified lubricant base oil. This production method does not alter the structure of the existing hydrocarbon species in the oil, and its properties depend on the properties of the crude oil. The composition and content of hydrocarbons in the base oil determine the quality of the finished oil, wherein the saturation of the hydrocarbons determines the viscosity index and stability of the base oil, and the isomerization/branching degree of the hydrocarbons determines the low-temperature fluidity of the base oil. The normal paraffin (wax) has high pour point and the polycyclic aromatic hydrocarbon has poor oxidation stability, and the normal paraffin (wax) and the polycyclic aromatic hydrocarbon are not ideal components of base oil. If chemical methods such as hydrofinishing, hydrocracking, catalytic dewaxing, isodewaxing, and hydrosaturation are used, these components can be converted into desirable components, thereby significantly improving the properties of the base oil. Among these chemical methods, the most important method is isomerization dewaxing, which can convert normal paraffin (wax) in high wax content raw materials, such as fischer-tropsch wax, vacuum distillate, propane deasphalted oil, hydrocracking tail oil, cerate, wax oil and the like, into isoparaffin, and can realize great improvement of low temperature performance and comprehensive performance of base oil with less loss of viscosity index by matching with hydrorefining and other operation processes.

Taking Fischer-Tropsch wax as an example: in the product of the low temperature Fischer-Tropsch synthesis, the waxy component comprises soft wax (C)₂₀-C₃₀) And hard waxes (A), (B), (C)>C₃₀) The main component is straight-chain alkane, almost no sulfur, nitrogen and aromatic hydrocarbon exist, and the lubricating oil is a high-quality high-grade lubricating oil base oil raw material. The technical key point of converting the Fischer-Tropsch synthetic wax product into the high-grade lubricating oil base oil is that the low-temperature flow property of the oil product, namely the freezing point is reduced, can be improved under the condition of keeping the high viscosity index, and can be realized through hydrocracking and hydroisomerization reaction.

Many patents have been published at home and abroad, for example, US5834522 discloses a process for producing a lubricant base oil from a fischer-tropsch synthesis product as a feedstock, which is hydroisomerized in a hydroisomerization reaction zone, the resulting oil is separated by distillation, and the bottoms of the distillation column are dewaxed to obtain an oil and a non-oil fraction. US5882505 discloses a process for producing lube base oil by converting fischer-tropsch wax having a boiling point greater than 370 ℃ in a countercurrent reactor, wherein the feedstock is contacted with a hydroisomerization catalyst in a fixed bed reactor, and the product of the reaction is contacted with a hydrodewaxing catalyst in at least one fixed bed reactor to produce the desired product, wherein the hydroisomerization product is in countercurrent flow to a hydrogen-containing gas. CN1688674 discloses a multi-step process for the production of a heavy lubricant base oil from fischer-tropsch wax, which comprises hydrodewaxing the wax in a first hydrodewaxing stage to produce an isomerate of a partially dewaxed heavy lubricant base oil fraction, and then hydrodewaxing said heavy lubricant fraction in one or more successive hydrodewaxing stages, removing hydrocarbons below the heavy lubricant fraction, to produce a heavy lubricant base oil. CN1703488 discloses a process for the preparation of fuel and lubricant base oils from fischer-tropsch wax comprising (1) hydrodewaxing the fischer-tropsch wax to produce an isomerate comprising fuel and a partially hydrodewaxed base oil fraction, (2) separating the two fractions, (3) separating the partially hydrodewaxed base oil fraction into a heavy fraction and a lower boiling fraction, (4) further hydrodewaxing the lower boiling and heavy fractions, respectively, to produce lubricant base oils including a heavy lubricant base stock. CN101230290 discloses a method for producing solvent oil, lubricant base oil and heavy wax from fischer-tropsch wax, which comprises fractionating the whole fraction product obtained by wax conversion in a hydrorefining zone to obtain a solvent oil light fraction, separating the base oil fraction product, performing hydroisomerization conversion, and directly hydrorefining the remaining heavy fraction to obtain the decolorized wax. US7198710 discloses a process for producing a high viscosity index lube base stock from fischer-tropsch wax by fractionating fischer-tropsch wax to obtain a light fraction and a heavy fraction, and then subjecting the light fraction and the heavy fraction to respective hydrodewaxing to reduce the pour point of the feed, thereby obtaining a light lube base stock having a pour point meeting the requirements. When heavy component is subjected to hydroisomerization dewaxing, the pour point of the heavy component is further reduced by adopting a solvent dewaxing method due to unqualified pour point, and finally the heavy lubricating oil base oil product with the pour point meeting the requirement is obtained.

In the above process, the conventional hydroisomerization dewaxing catalyst is used in its entirety in the hydrodewaxing unit, which has the following disadvantages: when using full-distillate or wide-distillate waxy oils as feed, it is difficult to have both light and heavy base components meet pour point and viscosity index requirements. When the pour point of the heavy base oil component is qualified, the viscosity index loss of the light base oil component is large, and API III light lubricating oil base oil products with the viscosity index of more than 120 are difficult to produce; while the viscosity index of the light base oil component is acceptable, the heavy component is not an acceptable lubricant base oil product. When the traditional hydrocracking catalyst is adopted, no matter the full-fraction or wide-fraction waxy oil is used as a feed, most of light and heavy base oil products can simultaneously meet the requirements of pour points and viscosity indexes, but a large amount of cracking products are generated in the process, and the yield of the light and heavy base oil is too low, so that the process economy is seriously influenced. The problems of low yield and poor product performance in the existing production of light and heavy high-viscosity index lubricating oil base oil can be solved to a certain extent by fractionating raw materials and adopting narrow-fraction Fischer-Tropsch wax as a feeding method for hydroisomerization dewaxing or a more complicated feeding method for circulating hydroisomerization dewaxing, but a plurality of raw material tanks and a plurality of separators are required to be arranged, so that the construction investment of the device is increased; in addition, in actual production, raw materials are frequently switched and technological parameters are frequently adjusted, so that the operation difficulty of the device is increased and a large amount of unqualified products are produced.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a method for hydro-conversion of a high-wax-content raw material, and the high-wax-content raw material can be used for preparing the lubricating oil base oil with low pour point and high viscosity index in high yield through a simple hydrogenation pretreatment, hydroisomerization, hydrofining and fractionation process. The technological core is the hydroisomerization process based on the molecular sieve catalyst with a combined TON structure and MTW structure, so that each component in the wide distillation range raw material can be converted into an isomeric product with high selectivity, thereby realizing the improvement of the product yield and performance at the same time.

The main content of the high wax content raw material hydro-conversion method of the invention comprises: the high wax content raw material firstly enters a hydrogenation pretreatment reaction zone to complete the hydrogenation saturation, the hydrogenation desulfurization, the hydrogenation denitrification and the hydrogenation deoxidation of non-alkane components in the raw material; the obtained hydrogenation pretreatment oil enters a hydroisomerization reaction zone, and the hydroisomerization of the hydrogenation pretreatment oil is completed on a specific combined catalyst; the obtained hydrogenation isomeric oil enters a hydrogenation refining reaction zone for further treatment to obtain a crude product; the crude product is fractionated by an atmospheric/vacuum tower to obtain base oil, diesel oil, gasoline and other products.

The technical scheme of the invention comprises the following implementation steps:

1) mixing the high wax content raw material and hydrogen gas, feeding the mixture into a hydrogenation pretreatment reaction zone, and adding the mixture on a hydrogenation pretreatment catalyst at the temperature of 150-350 ℃, the hydrogen partial pressure of 1.0-20MPa and the volume space velocity of the raw oil of 0.2-5h^-1Under the condition that the hydrogen-oil ratio is 100:1-3000:1, completing the hydrogenation saturation, the hydrogenation desulfurization, the hydrogenation denitrification and the hydrogenation deoxidation of non-alkane components in the raw materials to obtain hydrogenation pretreatment oil;

2) the hydrogenation pretreatment oil obtained in the step 1) enters a hydrogenation isomerization reaction zone, the reaction temperature is 200-^-1Carrying out hydroisomerization reaction under the condition that the hydrogen-oil ratio is 100:1-3000:1 to finish the hydroisomerization and proper hydrocracking reaction of the hydrogenated pretreated oil to obtain hydroisomerization oil;

3) the hydroisomerized oil obtained in the step 2) enters a hydrofining reaction zone, the reaction temperature is 150-350 ℃, the hydrogen partial pressure is 1.0-20MPa, and the volume space velocity of the raw oil is 0.2-5h on a hydrofining catalyst^-1Under the condition that the hydrogen-oil ratio is 100:1-3000:1, further hydrogenation saturation of the hydroisomerized oil is completed to obtain a crude product;

4) feeding the crude product obtained in the step 3) into a normal/reduced pressure tower, and fractionating to obtain products such as gasoline, diesel oil and base oil;

wherein, the combined catalyst in the step 2) is as follows: the catalyst is prepared by combining a molecular sieve with a TON structure as a carrier, a catalyst A prepared by loading platinum, palladium and/or iridium and a molecular sieve with an MTW structure as a carrier, and a catalyst B prepared by loading platinum, palladium and/or iridium according to a certain proportion;

wherein the volume ratio of the combined catalyst A to the combined catalyst B in the step 2) is 1:10-10: 1;

wherein, the combination mode of the catalysts A and B in the step 2) is that the catalyst A is arranged above the catalyst B, and the raw oil flows through the catalyst A and the catalyst B in sequence.

The method comprises the step 1), wherein the hydrogenation pretreatment catalyst is composed of a heat-resistant inorganic oxide as a carrier, one or more metals of cobalt, nickel, molybdenum and tungsten loaded on the carrier, and one or more auxiliary agents selected from nitrogen, phosphorus, sulfur or boron.

The method, wherein the heat-resistant inorganic oxide in the hydrogenation pretreatment catalyst in the step 1) is alumina and/or silica.

The method comprises the steps that in the hydrogenation pretreatment catalyst in the step 1), the loading component is one or more metals of cobalt, nickel, molybdenum and tungsten, and one or more assistants selected from nitrogen, phosphorus, sulfur or boron, the mass loading of the metals is 10-35wt%, and the mass loading of the assistants is 3-10 wt%.

The method, wherein, in the step 1), the preferable hydrogenation pretreatment reaction conditions are as follows: the temperature is 200 ℃ and 300 ℃, the hydrogen partial pressure is 2.0-15MPa, and the volume airspeed of the raw material oil is 0.2-3h^-1The hydrogen-oil ratio is 200:1-1000: 1.

The method described above, wherein the catalyst a in step 2) is a catalyst loaded with platinum, palladium and/or iridium metal components, using a molecular sieve having a TON structure as a carrier.

The method described in step 2), wherein the catalyst B is a catalyst which uses a molecular sieve having an MTW structure as a carrier and supports a platinum, palladium and/or iridium metal component.

The method, wherein the molecular sieve with TON structure is one or more of ZSM-22, Me-ZSM-22 (one or more of Me ═ Zn, Mg, Mn, Co, Cr, Cu, Fe, Cd and Ni), Theta-1, KZ-2, ISI-1 and NU-10.

The method is characterized in that the molecular sieve with the MTW structure is one or more of ZSM-12, NU-13, CZH-5, TPZ-12, VS-12 and Theta-3.

The method, wherein the volume ratio of the catalyst A to the catalyst B in the step 2) is 1:5-5: 1.

The method, wherein the volume ratio of the catalyst A to the catalyst B in the step 2) is 1:3-3: 1.

The method, wherein the acid amount of the catalyst A in the step 2) is 1.2-2.0mmol (NH)₃) Per g, the acid content of catalyst B is from 0.8 to 1.6mmol (NH)₃)/g。

The method comprises the step 2), wherein the mass loading of the active metal in the catalyst A is 0.1-0.5wt%, and the mass loading of the active metal in the catalyst B is 0.3-0.8 wt%.

The method comprises the step 2) of enabling the mesoporous volume of the catalyst B to be 0.18-0.50 ml/g.

The method, wherein the hydroisomerization reaction conditions in step 2) are as follows: the temperature is 250-400 ℃, the hydrogen partial pressure is 1.0-15MPa, and the volume space velocity of the raw oil is 0.2-2h^-1The hydrogen-oil ratio is 200:1-1000: 1.

The method, wherein the preferred hydroisomerization reaction conditions in step 2) are as follows: the temperature is 280-380 ℃, the hydrogen partial pressure is 1.0-15MPa, and the volume space velocity of the raw oil is 0.2-2h^-1The hydrogen-oil ratio is 200:1-800: 1.

The method comprises the step 3), wherein the hydrogenation refined catalyst consists of a heat-resistant inorganic oxide as a carrier, one or more metals of platinum, palladium and iridium loaded on the carrier, and one or more assistants selected from cobalt, nickel, molybdenum and tungsten, the mass loading of the metals is 0.2-1.0wt%, and the mass loading of the assistants is 0.3-1.5 wt%.

The method, wherein the heat-resistant inorganic oxide in the hydrofining catalyst in the step 3) is alumina and/or silica.

The method, wherein the hydrogenation refining reaction conditions in the step 3) are as follows: the temperature is 180-320 ℃, the hydrogen partial pressure is 1.0-15MPa, and the volume space velocity of the raw oil is 0.5-2h^-1The hydrogen-oil ratio is 200:1-1000: 1.

The method comprises the step of sequentially fractionating the crude product obtained in the step 3) in atmospheric and vacuum towers to obtain products such as gasoline, kerosene, diesel oil and base oil.

The method, wherein the atmospheric and vacuum distillation columns in the step 4) are well known in the art, generally comprises one or more operation units of flash evaporation, atmospheric distillation and vacuum distillation columns, and realizes the separation of products with different distillation ranges.

In the method, the high-wax-content raw material is one or more of Fischer-Tropsch synthesis wax, vacuum distillate oil, propane deasphalted oil, hydrocracking tail oil, cerate and wax oil; fractionating to obtain the products including gasoline, diesel oil and base oil of lubricating oil.

Compared with the prior art, the hydro-conversion method of the high-wax content raw material has the following advantages: the staged conversion of the high wax content raw material is realized by a combined mode of catalyst preparation; the raw material has strong adaptability, and can adapt to various petroleum-based and Fischer-Tropsch synthesis raw materials; the process conditions are simple, the hydroisomerized product does not need to be circularly treated, and the target product can be obtained by one-time passing; the base oil product prepared by the method has high yield and good performance.

Drawings

FIG. 1 is a schematic process flow diagram.

Detailed Description

The invention will be further described with reference to specific examples, but it should be understood that the invention is not limited thereto.

The information and preparation method of the prehydrogenation catalyst, the hydroisomerization catalyst and the hydrofining catalyst used in the embodiment of the invention are as follows:

1. hydrogenation pretreatment catalyst H1

The hydrogenation pretreatment catalyst H1 was prepared by a conventional impregnation method. The catalyst is composed of refractory inorganic oxide alumina and/or silica as carrier, one or more metals of cobalt, nickel, molybdenum and tungsten loaded on the carrier, and one or more assistants selected from nitrogen, phosphorus, sulfur or boron. The total content of cobalt, nickel, molybdenum and tungsten (in the following examples, these four element ratios are the same by mass) was 30 wt%, the total content of nitrogen, phosphorus, sulfur and boron (in the following examples, these four element ratios are the same by mass) was 8wt%, and the balance was alumina and/or silica (in the following examples, alumina and silica in a mass ratio of 1: 1) based on the weight percentage of the catalyst.

2. Hydroisomerization catalysts A and B

The hydroisomerization catalyst A is prepared by a conventional impregnation method. The catalyst is composed of a molecular sieve having TON structure such as ZSM-22 (ZSM-22 is used in the following examples) as a carrier and one or more metals selected from platinum, palladium and/or iridium. Based on the weight percentage of the catalyst, the total content of platinum, palladium and/or iridium (in the following examples, the three elements with the same mass are adopted) is 0.3 wt%, the rest is molecular sieve, the acid content of the catalyst A is 1.8mmol (NH)₃)/g。

The hydroisomerization catalyst B is prepared by a conventional impregnation method. The catalyst consists of a molecular sieve with MTW structure, such as ZSM-12 (ZSM-12 is used in the following examples), as a carrier, and one or more metals selected from platinum, palladium and/or iridium. Based on the weight percentage of the catalyst, the total content of platinum, palladium and/or iridium (the three elements with the same mass are adopted in the following examples) is 0.5wt%, the rest is molecular sieve, and the acid content of the catalyst B is 1.0mmol (NH)₃) The mesoporous volume of the catalyst B is 0.32 ml/g.

3. Hydrofining catalyst H2

The hydrogenation pretreatment catalyst H2 was prepared by a conventional impregnation method. The catalyst is composed of refractory inorganic oxide alumina and/or silica as carrier, one or more metals of platinum, palladium and iridium loaded on the carrier, and one or more assistants selected from cobalt, nickel, molybdenum and tungsten. The total content of platinum, palladium and/or iridium (in the following examples these three element ratios are equal in mass) was 0.3 wt%, the total content of cobalt, nickel, molybdenum and tungsten (in the following examples these four element ratios are equal in mass) was 1 wt%, and the balance was alumina and/or silica (in the following examples alumina and silica in a mass ratio of 1: 1).

The examples of the invention use a Fischer-Tropsch wax as the starting material and the properties are shown in Table 1.

The brief process flow diagram of the present invention is shown in FIG. 1. Feeding raw materials at the top and discharging products from the bottom in a hydrogenation pretreatment reactor; in the hydroisomerization reactor, raw materials are fed at the top, and products flow out from the bottom; in the hydrofining reactor, raw materials are fed at the top, and products flow out from the bottom; feeding in a normal pressure distillation tower at the middle part of the tower, fractionating at the top of the tower to obtain light hydrocarbon (gasoline), fractionating at the middle upper part to obtain diesel oil, fractionating at the middle lower part to obtain base oil and heavy wax flowing out from the bottom;

example 1

A hydrogenation pretreatment catalyst H1 is adopted in the hydrogenation pretreatment reactor, the reaction conditions are 250 ℃, 4MPa and the space velocity is 2.0H^-1Hydrogen to oil ratio of 500; the hydroisomerization reactor adopts hydroisomerization catalysts A and B, the filling mode of the hydroisomerization catalysts A and the hydroisomerization catalysts B is that A is arranged above B, the filling volume ratio is 1:1, the reaction conditions are 320 ℃, 12MPa and the space velocity is 0.8h^-1Hydrogen to oil ratio of 500; the hydrofining reactor adopts hydrofining catalyst H2, the reaction conditions are 220 ℃, 5MPa and the space velocity is 1.0H^-1Hydrogen to oil ratio of 500. The product yields of the raw materials shown in table 1 after conversion and fractionation through the reaction scheme are shown in table 2, and the properties of the base oil products are shown in table 3.

Example 2

A hydrogenation pretreatment catalyst H1 is adopted in the hydrogenation pretreatment reactor, the reaction conditions are 230 ℃, 4MPa and the space velocity is 2.0H^-1Hydrogen to oil ratio 600; the hydroisomerization reactor adopts hydroisomerization catalysts A and B, the filling mode of the hydroisomerization catalysts A and the hydroisomerization catalysts B is that A is above B, the filling volume ratio is 1:2, the reaction conditions are 315 ℃, 13MPa and the space velocity is 0.8h^-1Hydrogen to oil ratio of 500; the hydrofining reactor adopts hydrofining catalyst H2, the reaction conditions are 240 ℃, 6MPa and the space velocity is 1.0H^-1Hydrogen to oil ratio of 500. The product yields of the raw materials shown in table 1 after conversion and fractionation through the reaction scheme are shown in table 2, and the properties of the base oil products are shown in table 3.

Example 3

A hydrogenation pretreatment catalyst H1 is adopted in the hydrogenation pretreatment reactor, the reaction conditions are 270 ℃, 5MPa and the space velocity is 2.0H^-1Hydrogen to oil ratio 600; the hydroisomerization reactor adopts hydroisomerization catalysts A and B, the filling mode of the hydroisomerization catalysts A and the hydroisomerization catalysts B is that A is arranged above B, the filling volume ratio is 1:3, the reaction conditions are 310 ℃, 15MPa and the space velocity is 0.8h^-1Hydrogen to oil ratio of 500; the hydrofining reactor adopts hydrofiningPreparing a catalyst H2 under the reaction conditions of 240 ℃, 6MPa and space velocity of 1.0H^-1Hydrogen to oil ratio of 500. The product yields of the raw materials shown in table 1 after conversion and fractionation through the reaction scheme are shown in table 2, and the properties of the base oil products are shown in table 3.

Example 4

A hydrogenation pretreatment catalyst H1 is adopted in the hydrogenation pretreatment reactor, the reaction conditions are 260 ℃, 3MPa and the space velocity is 2.0H^-1Hydrogen to oil ratio of 500; the hydroisomerization reactor adopts hydroisomerization catalysts A and B, the filling mode of the hydroisomerization catalysts A and the hydroisomerization catalysts B is that A is above B, the filling volume ratio is 1:5, the reaction conditions are 305 ℃, 15MPa and the space velocity is 0.8h^-1Hydrogen to oil ratio of 500; the hydrofining reactor adopts hydrofining catalyst H2, the reaction conditions are 270 ℃, 5MPa and the space velocity is 1.0H^-1Hydrogen to oil ratio of 500. The product yields of the raw materials shown in table 1 after conversion and fractionation through the reaction scheme are shown in table 2, and the properties of the base oil products are shown in table 3.

Comparative example 1

A similar process flow to that of the present example was used. A hydrogenation pretreatment catalyst H1 is adopted in the hydrogenation pretreatment reactor, the reaction conditions are 250 ℃, 4MPa and the space velocity is 2.0H^-1Hydrogen to oil ratio of 500; the hydroisomerization reactor adopts a hydroisomerization catalyst A, and the reaction conditions are 320 ℃, 12MPa and 0.8h of space velocity^-1Hydrogen to oil ratio of 500; the hydrofining reactor adopts hydrofining catalyst H2, the reaction conditions are 220 ℃, 5MPa and the space velocity is 1.0H^-1Hydrogen to oil ratio of 500. The product yields of the raw materials shown in table 1 after conversion and fractionation through the reaction scheme are shown in table 2, and the properties of the base oil products are shown in table 3.

Comparative example 2

A similar process flow to that of the present example was used. A hydrogenation pretreatment catalyst H1 is adopted in the hydrogenation pretreatment reactor, the reaction conditions are 230 ℃, 4MPa and the space velocity is 2.0H^-1Hydrogen to oil ratio 600; the hydroisomerization reactor adopts a hydroisomerization catalyst A, the reaction conditions are 315 ℃, 13MPa and the space velocity is 0.8h^-1Hydrogen to oil ratio of 500; the hydrofining reactor adopts hydrofining catalyst H2, the reaction conditions are 240 ℃, 6MPa and space velocity of 1.0H^-1Hydrogen to oil ratio of 500. The raw materials shown in the table 1 are converted and fractionated through the reaction flow to obtainThe product yields are shown in Table 2, and the base oil product properties are shown in Table 3.

Comparative example 3

A similar process flow to that of the present example was used. A hydrogenation pretreatment catalyst H1 is adopted in the hydrogenation pretreatment reactor, the reaction conditions are 270 ℃, 5MPa and the space velocity is 2.0H^-1Hydrogen to oil ratio 600; the hydroisomerization reactor adopts a hydroisomerization catalyst B, the reaction conditions are 310 ℃, 15MPa and the space velocity is 0.8h^-1Hydrogen to oil ratio of 500; the hydrofining reactor adopts hydrofining catalyst H2, the reaction conditions are 240 ℃, 6MPa and the space velocity is 1.0H^-1Hydrogen to oil ratio of 500. The product yields of the raw materials shown in table 1 after conversion and fractionation through the reaction scheme are shown in table 2, and the properties of the base oil products are shown in table 3.

Comparative example 4

A similar process flow to that of the present example was used. A hydrogenation pretreatment catalyst H1 is adopted in the hydrogenation pretreatment reactor, the reaction conditions are 260 ℃, 3MPa and the space velocity is 2.0H^-1Hydrogen to oil ratio of 500; the hydroisomerization reactor adopts a hydroisomerization catalyst B, and the reaction conditions are 305 ℃, 15MPa and 0.8h of space velocity^-1Hydrogen to oil ratio of 500; the hydrofining reactor adopts hydrofining catalyst H2, the reaction conditions are 270 ℃, 5MPa and the space velocity is 1.0H^-1Hydrogen to oil ratio of 500. The product yields of the raw materials shown in table 1 after conversion and fractionation through the reaction scheme are shown in table 2, and the properties of the base oil products are shown in table 3.

As can be seen from table 2, the yield of base oil is significantly increased and the yields of light hydrocarbons and diesel, which are of lower value, are significantly reduced by the process of the present invention compared to the comparative examples. Meanwhile, as can be seen from Table 3, the pour points of comparative examples 1 to 4 are higher than-15 ℃, and the pour points of the corresponding base oils cannot be met, which means that the products prepared by the comparative examples have unqualified quality. By adopting the method, the lube base oil with high viscosity index and low pour point can be prepared.

TABLE 1 Fischer-Tropsch wax feed oil Properties

Item	Raw materials
		Density (15 ℃), kg/m³	875
Sulfur content, ppm	<5
		Nitrogen content, ppm	<5
Distillation range, deg.C
		Initial boiling point	312
10％	366
		30％	413
50％	445
		70％	483
90％	517
		95％	529
End point of distillation	556

TABLE 2 product yield

TABLE 3 base oil product Properties

The method can obtain the base oil with high yield, low pour point and high viscosity index, and has simple process and lower energy consumption.

Claims

1. A method for hydroconversion of a high wax content feedstock, comprising the steps of:

1) mixing the high wax content raw material and hydrogen gas, feeding the mixture into a hydrogenation pretreatment reaction zone, and adding the mixture on a hydrogenation pretreatment catalyst at the temperature of 150-350 ℃, the hydrogen partial pressure of 1.0-20MPa and the volume space velocity of the raw oil of 0.2-5h^-1Under the condition that the hydrogen-oil ratio is 100:1-3000:1, completing the hydrogenation saturation, the hydrogenation desulfurization, the hydrogenation denitrification and the hydrogenation deoxidation of non-alkane components in the raw materials to obtain hydrogenation pretreatment oil; the high wax content raw material is one or more of Fischer-Tropsch synthetic wax, vacuum distillate oil, propane deasphalted oil, hydrocracking tail oil, cerate and wax oil;

3) the hydroisomerized oil obtained in the step 2) enters a hydrofining reaction zone and is hydrogenatedOn a refined catalyst, the reaction temperature is 150-350 ℃, the hydrogen partial pressure is 1.0-20MPa, and the volume space velocity of raw oil is 0.2-5h^-1Under the condition that the hydrogen-oil ratio is 100:1-3000:1, further hydrogenation saturation of the hydroisomerized oil is completed to obtain a crude product;

4) feeding the crude product obtained in the step 3) into an atmospheric tower distillation and/or reduced pressure distillation tower, and fractionating to obtain gasoline, diesel oil and base oil products;

wherein the acid content of the catalyst A in the step 2) is 1.2-2.0mmol NH₃The acid content of the catalyst B is 0.8 to 1.6mmol NH₃(ii)/g; the mass loading of the active metal in the catalyst A is 0.1-0.5wt%, and the mass loading of the active metal in the catalyst B is 0.3-0.8 wt%;

wherein, the mesoporous volume of the catalyst B in the step 2) is 0.18-0.50 ml/g;

wherein, the position of the combined catalyst in the step 2) in the catalyst bed layer is A, B and below, and the raw oil flows through A and B in sequence.

2. The method according to claim 1, wherein the molecular sieve with TON structure is one or more of ZSM-22, Me-ZSM-22, Theta-1, KZ-2, ISI-1 and NU-10, wherein Me in Me-ZSM-22 is one or more of Zn, Mg, Mn, Co, Cr, Cu, Fe, Cd and Ni; the molecular sieve with the MTW structure is one or more of ZSM-12, NU-13, CZH-5, TPZ-12, VS-12 and Theta-3.

3. The method according to claim 1, wherein the volume ratio of the catalysts A and B in the step 2) is 1:5-5: 1.

4. The method as claimed in claim 1, wherein the hydrogenation pretreatment catalyst in step 1) comprises a refractory inorganic oxide as a carrier, one or more metals selected from cobalt, nickel, molybdenum and tungsten and one or more assistants selected from nitrogen, phosphorus, sulfur or boron, wherein the mass loading of the metals is 10-35wt%, and the mass loading of the assistants is 3-10 wt%.

5. The method according to claim 1, wherein the hydrogenation pretreatment reaction conditions in step 1) are as follows: the temperature is 200-^-1The hydrogen-oil ratio is 200:1-1000: 1.

6. The method according to claim 1, wherein the hydrofining catalyst in the step 3) is composed of a refractory inorganic oxide as a carrier, one or more metals selected from platinum, palladium and iridium and one or more assistants selected from cobalt, nickel, molybdenum and tungsten, wherein the mass loading of the metals is 0.2-1.0wt%, and the mass loading of the assistants is 0.3-1.5 wt%.

7. The method according to claim 1, wherein the hydrofining reaction conditions in step 3) are as follows: the temperature is 180-320 ℃, the hydrogen partial pressure is 2.0-15MPa, and the volume space velocity of the raw oil is 0.5-2h^-1The hydrogen-oil ratio is 200:1-1000: 1.

8. The method of claim 1, wherein the fractionating produces gasoline, diesel, and lubricant base oils.