A kind of polystyrene white oil and preparation method thereof

Abstract

The present invention provides a polystyrene white oil and a preparation method thereof. The preparation method comprises the following steps: subjecting a heavy fraction of hydroisomerization oil to a white oil hydrogenation reaction in the presence of a white oil hydrogenation catalyst to obtain polystyrene white oil; wherein the white oil hydrogenation catalyst comprises an amorphous silica-alumina-based support and an active metal, wherein the active metal comprises platinum and palladium. The present invention utilizes a catalyst having high catalytic activity to compound the heavy fraction of hydroisomerization oil for hydrorefining to obtain a high-viscosity polystyrene white oil having excellent oxidative stability, photothermal stability, and all indicators meeting the standards for polystyrene white oil.

Description

Technical Field

[0001] The present invention relates to the technical field of polystyrene white oil preparation, in particular to polystyrene white oil and a preparation method thereof. Background Art

[0002] Polystyrene (PS), a thermoplastic formed by the polymerization of styrene monomers, is colorless, odorless, non-toxic, and glossy, transparent solid. Its excellent electrical insulation properties allow for a wide range of applications. It can be used to create transparent or brightly colored products, such as instrument housings and optical components. When made into foam plastic, it can be used for soundproofing packaging, shockproofing, and life-saving materials. In polystyrene production, a white oil, polystyrene white oil, is required. It serves as an internal lubricant, plasticizer, and diluent. Its excellent stability and low volatility improve the flow characteristics of polystyrene (PS) and polypropylene (PP) during molding.

[0003] Polystyrene white oil is produced from petroleum lubricant oil fractions that have been subjected to deep (tertiary or quadruple) hydrorefining to achieve a food-grade aromatic content. It is a colorless, non-toxic, odorless, non-fluorescent, and transparent oily liquid. Due to the limited availability of paraffinic crude oil, lubricant manufacturers primarily rely on various intermediate crudes. Intermediate crude oils are widely distributed and account for over 40% of the total lubricant base oil production. Naphthenic crude oil is a scarce petroleum resource, and its high-end products include ultra-high voltage transformer oil, rubber filler oil, and food-grade white oil. There are two main methods for producing white oil: one is to dewax paraffinic mineral oil fractions, using the wax oil extracted from crude oil distillation, hydrodepressing the pour point of the mineral oil, and then deep hydrorefining; the other is to use naphthenic distillates, obtained from the distillation of naphthenic crude oil, solvent or isomerization dewaxing, and chemical refining. White oil produced from paraffinic mineral oil is typically high-viscosity white oil, while that produced from naphthenic mineral oil is typically low-pour point white oil.

[0004] Polystyrene (PS) white oil is used in PS production. The PS white oil standard sets high requirements for indicators such as the 5% carbon number, cycloparaffinic carbon content, viscosity, aromatic content, flash point, appearance, oxidation, and optical and thermal stability. To meet the requirements for extremely low aromatic content and compatibility of PS white oil, cycloalkyl oil can be used for production. It is necessary to select a cycloalkyl oil with a 5% carbon number of no less than 22 and a low distillate yield. If paraffinic base oil is used as the raw material, it has the advantage of low aromatic content, but it also has the disadvantages of low cycloparaffin content, low CN value, low viscosity, and poor compatibility. However, the production of PS white oil by blending intermediate base oils or cycloalkyl oils with paraffinic base oils is feasible and can compensate for the shortcomings of a single raw material.

[0005] In the prior art, CN106479565B discloses a method for producing polystyrene white oil, which comprises subjecting the distillate oil of cycloalkyl crude oil to solvent refining to obtain refined oil, and subjecting the refined oil to hydrogenation and fractionation to obtain polystyrene white oil. The hydrogenation process includes hydrogenation treatment, catalytic dewaxing, hydrorefining and deep hydrogenation saturation of aromatics. The deep hydrogenation saturation catalysts used are Shell's supplementary refining catalyst LN-5 and the industrialized white oil hydrogenation catalyst RLF-10 of the Institute of Petroleum Science and Technology. The process conditions are a hydrogen partial pressure of 12.0-17.0 MPa, a reaction temperature of 200-260°C, and a volume space velocity of 0.4-1.0 h -1 The product is fractionated, and the fraction above 340°C is used as polyolefin white oil. This process involves hydrogenating the cycloalkyl feedstock through four stages: hydrorefining, catalytic dewaxing, supplementary refining, and deep aromatic saturation. This process has the disadvantages of a long process flow, significant product yield loss, and high supporting equipment costs.

[0006] CN114479934A discloses a polystyrene-specific white oil and its preparation method. The method comprises: dewaxing a paraffin-based distillate oil using a ketone-benzene dewaxing unit to obtain a dewaxed refined oil; subjecting the dewaxed refined oil to hydrogenation, hydroisomerization, and hydrorefining to obtain a three-stage hydrogenation product oil; and fractionating the product oil to obtain a fraction above 430°C to obtain the polystyrene white oil. The hydrorefining process utilizes a ZSM-5 catalyst carrier and a metal selected from the group consisting of Pt and Pd. This method utilizes ZSM-5 as a catalyst carrier, but ZSM-5 powder with a low silicon-to-aluminum ratio is generally highly acidic, resulting in a higher cracking activity as a post-refining catalyst, which can affect product yield. Summary of the Invention

[0007] To solve the above technical problems, the purpose of the present invention is to provide a polystyrene white oil and a preparation method thereof, wherein the high viscosity polystyrene white oil is obtained by compounding the hydroisomerization oil and hydrorefining the hydroisomerized oil using a catalyst with high catalytic activity.

[0008] To achieve the above object, the present invention provides a method for preparing polystyrene white oil, which comprises the following steps:

[0009] The heavy fraction of the hydroisomerization oil is subjected to a white oil hydrogenation reaction under the action of a white oil hydrogenation catalyst to obtain polystyrene white oil;

[0010] The heavy fraction of the hydroisomerization oil is a combination of a heavy fraction with a temperature of >380°C of a paraffin-based oil minus two-line isomerization product and a heavy fraction with a temperature of >380°C of an intermediate-based oil minus four-line isomerization product, or a heavy fraction with a temperature of >380°C of a paraffin-based oil minus two-line isomerization product and a heavy fraction with a temperature of >360°C of a cycloalkyl-based oil minus three-line isomerization product.

[0011] The white oil hydrogenation catalyst comprises an amorphous silica-alumina-based support and an active metal, wherein the active metal comprises platinum and palladium.

[0012] In the preparation method of the above-mentioned polystyrene white oil, preferably, the heavy fraction of the hydroisomerization product oil is a combination of a 380-480°C fraction of a paraffin-based minus two-line isomerization product oil and a 380-520°C fraction of an intermediate-based minus four-line isomerization product oil, or a combination of a 380-480°C fraction of a paraffin-based minus two-line isomerization product oil and a 360-500°C fraction of a cycloalkyl-based minus three-line isomerization product oil.

[0013] In the preparation method of the above-mentioned polystyrene white oil, preferably, the heavy fraction of the hydroisomerization product oil is a combination of the 380-480°C fraction of the paraffin-based minus two-line isomerization product oil and the 380-520°C fraction of the intermediate-based minus four-line isomerization product oil in a mass ratio of 1:12-15.

[0014] In the preparation method of the above-mentioned polystyrene white oil, preferably, the heavy fraction of the hydroisomerization product oil is a combination of a 380-480°C fraction of a paraffin-based minus two-line isomerization product oil and a 360-500°C fraction of a cycloalkyl-based minus three-line isomerization product oil in a mass ratio of 1:4-8.

[0015] In the above-mentioned preparation method of polystyrene white oil, preferably, the white oil hydrogenation reaction conditions include: reaction pressure of 12-16 MPa, reaction temperature of 210-240°C, volume space velocity of 0.5-1.0h -1 , the hydrogen-oil ratio is 300-600:1. The more preferred conditions for the white oil hydrogenation reaction are: reaction pressure 15 MPa, reaction temperature 230°C, space velocity 0.6 h -1 , hydrogen-to-oil ratio 500:1.

[0016] The above-mentioned method for preparing polystyrene white oil preferably further comprises reducing the white oil hydrogenation catalyst before the white oil hydrogenation reaction; the reduction conditions include: hydrogen pressure of 1.0-2.0 MPa, reduction temperature of 200-400°C, and reduction time of 10-16 hours.

[0017] In the above-mentioned method for preparing polystyrene white oil, preferably, the heavy fraction of the hydroisomerization oil is prepared by the following method:

[0018] The raw oil is subjected to hydrogenation pre-refining to obtain hydrogenation pre-refined oil respectively; the hydrogenation pre-refined oil is subjected to hydrogenation isomerization to obtain hydrogenation isomerization product oil respectively; and the heavy fraction of the hydrogenation isomerization product oil is obtained by fractionation;

[0019] The reaction conditions for hydrogenation pre-refining include: reaction pressure of 12-17 MPa, reaction temperature of 350-390°C, volume space velocity of 0.3-1.0 h -1 , hydrogen-to-oil ratio is 300-1000:1; hydroisomerization reaction conditions include: reaction pressure of 8-16 MPa, reaction temperature of 320-370°C, volume space velocity of 0.6-1.5h -1 , hydrogen-to-oil ratio 300-800:1.

[0020] The hydrogenation reaction in the preparation method of the polystyrene white oil of the present invention comprises:

[0021] Hydrogenation pre-refining reaction: Under high-pressure hydrogen conditions, the crude oil fraction is subjected to hydrogenation pre-refining, desulfurization and denitrogenation reactions are carried out at a higher temperature, and most of the aromatics are saturated to obtain refined oil;

[0022] Hydroisomerization reaction: The refined oil enters the hydroisomerization reactor for isomerization reaction. The function of the hydroisomerization reaction is to convert straight-chain alkanes into isoalkanes to dewax the refined oil and lower the pour point, thereby obtaining isomerized oil. The isomerized oil is fractionated to obtain light and heavy fractions. The heavy fraction of paraffinic isomerized oil and the heavy fraction of naphthenic isomerized oil, or the heavy fraction of paraffinic isomerized oil and the heavy fraction of intermediate isomerized oil are mixed in a certain proportion to obtain mixed isomerized oil.

[0023] White oil hydrogenation reaction: The mixed isomerized oil heavy fraction is then fed into the white oil hydrogenation reactor, where the mixed isomerized oil undergoes olefin saturation, and monocyclic and polycyclic aromatic hydrocarbon saturation reactions, thereby deeply removing aromatic hydrocarbons.

[0024] In the white oil hydrogenation reaction section, the reactor is filled with a white oil hydrogenation catalyst, which is a modified amorphous silicon-aluminum-based precious metal white oil hydrogenation catalyst.

[0025] The hydrotreating pre-refining catalyst and hydroisomerization dewaxing catalyst used in the present invention can be homemade or commercially available. The hydrotreating pre-refining catalyst can use a conventional non-precious metal / Al2O3 catalyst, such as nickel-molybdenum-phosphorus, nickel-tungsten-phosphorus, molybdenum-tungsten-nickel type hydrogenation catalyst, or other catalysts with desulfurization, denitrogenation and aromatic saturation effects can be used; the isomerization dewaxing catalyst can use a precious metal-molecular sieve catalyst, or other catalysts with hydroisomerization effects can be used. More preferably, the hydrotreating pre-refining section can specifically use commercially available HRK1058 (French Petrochemical Research Institute), LH-23 / LH-21 catalyst (Shell), PHT-01 catalyst (China Petroleum and Chemical Research Institute); the hydroisomerization catalyst can specifically use the hydroisomerization catalyst developed by China Petroleum and Chemical Research Institute, brand PIC802 catalyst, PIC812 catalyst, or PHI-01 catalyst, etc.

[0026] In the above-mentioned method for preparing polystyrene white oil, preferably, the feed oil for the hydroisomerization reaction satisfies the requirements that the aromatics content is no more than 6wt%, the sulfur content is no more than 10μg / g, and the nitrogen content is no more than 2μg / g.

[0027] In the above-mentioned method for preparing polystyrene white oil, preferably, the raw oil is any one of naphthenic base minus third-line distillate oil, intermediate base minus fourth-line distillate oil, and paraffin base minus second-line distillate oil.

[0028] In the above-mentioned method for preparing polystyrene white oil, preferably, the raw oil includes cycloalkyl vacuum distillate oil (including vacuum distillate line 3 and vacuum distillate line 4) and / or intermediate vacuum distillate oil (vacuum distillate line 4), and paraffin vacuum distillate oil (vacuum distillate line 2).

[0029] In the preparation method of the above-mentioned polystyrene white oil, preferably, the cycloalkyl vacuum distillate oil can be a distillate oil with a distillation range of 360-500°C formed by fractionating cycloalkyl crude oil, the intermediate-base vacuum distillate oil can be a distillate oil with a distillation range of 360-550°C formed by fractionating intermediate-base crude oil, and the paraffin-based vacuum distillate oil can be a distillate oil with a distillation range of 360-500°C formed by fractionating paraffin-based crude oil.

[0030] In the above-mentioned method for preparing polystyrene white oil, preferably, based on the total mass of the white oil hydrogenation catalyst, the content of platinum is 0.1-0.4 wt%, and the content of palladium is 0.2-0.4 wt%.

[0031] In the preparation method of the above-mentioned polystyrene white oil, preferably, the specific surface area of ​​the amorphous silica-alumina-based carrier is 371-442 m 2 ·g -1 , pore diameter is 11.4-13.6nm, pore volume is 1.22-1.56cm 3 ·g -1.

[0032] In the above-mentioned method for preparing polystyrene white oil, preferably, the white oil hydrogenation catalyst is prepared by the following method: amorphous silica-alumina material is modified with boric acid and urea in sequence, and then loaded with active metal to obtain the white oil hydrogenation catalyst.

[0033] In the above-mentioned method for preparing polystyrene white oil, preferably, the white oil hydrogenation catalyst is prepared by the following method:

[0034] S1: Silica sol and aluminum sol are stirred and mixed to form a gel, and the gel is dried and calcined to obtain an amorphous silica-alumina material.

[0035] S2: impregnating an amorphous silicon-alumina material with an equal volume of boric acid solution, removing the solid after impregnation, drying it, and calcining it to obtain a boric acid-modified support;

[0036] S3: mixing urea and the boric acid modified support and grinding them, calcining the obtained mixed particles in a closed state in two stages, and washing them to obtain an amorphous silica-alumina-based support;

[0037] S4: Immersing an equal volume of the amorphous silica-alumina-based support in a mixed solution containing a platinum source and a palladium source. After the impregnation is completed, the solid is taken out and dried and calcined to obtain the white oil hydrogenation catalyst.

[0038] The white oil hydrogenation catalyst used in the present invention utilizes a sol-gel method to prepare a silica-alumina sol carrier, which is then modified with boric acid and urea to form a highly dispersed platinum-palladium active metal carrier. The catalyst features low cost, a large specific surface area, a well-structured pore structure, high dispersion of active metals, and superior performance. The catalyst utilizes readily available raw materials, a hydrogenation process, and fractional distillation to produce polystyrene white oil, resulting in a high product yield and high-quality white oil, improving the economic efficiency of intermediate-base and naphthenic oils.

[0039] The white oil hydrogenation catalyst used in the preparation method of polystyrene white oil of the present invention has the advantages of high specific surface area, large pore volume and pore diameter, many acid active sites, large total weak acid content, slightly stronger B acidity, high active metal dispersion and good catalytic performance.

[0040] In the preparation method of a white oil hydrogenation catalyst, boric acid modification in a single modification increases the total acid and strong acid content of the carrier. Combined modification with boric acid and urea further increases the total acid content of the carrier, reduces the strong acid content, and improves the dispersion of active metals. Combined modification with boric acid and urea significantly increases the amount of B acid and reduces the amount of strong acid. The composite-modified silica-alumina sol is primarily composed of weak and medium-strong acids. White oil components have large molecular volumes and are mostly aromatic hydrocarbons with numerous branches, requiring the catalyst to have a large number of acidic sites to adsorb aromatic molecules. The white oil hydrogenation reaction operates at a relatively low space velocity, and strong acids can cause cracking of the white oil feedstock, so excessive amounts of strong acid should be avoided. This indicates that the silica-alumina sol catalyst after composite modification with boric acid and urea provides an optimal environment for deep refining of isomerized oils containing branched polycyclic aromatic hydrocarbons.

[0041] The preparation method of the white oil hydrogenation catalyst is simple and safe. The prepared white oil hydrogenation catalyst has an excellent pore structure (high specific surface area, large pore size), enhanced B acidity and highly dispersed active metals.

[0042] In the above-mentioned method for preparing polystyrene white oil, preferably, in step S1 of the white oil hydrogenation catalyst preparation method, the mass ratio of the silicon source calculated as SiO2 to the aluminum source calculated as Al2O3 is 3:7 to 5:5. Controlling the silicon-aluminum ratio within this range can improve the acidity of the amorphous silica-alumina material and the amorphous silica-alumina-based support.

[0043] In the above-mentioned method for preparing polystyrene white oil, preferably, in step S1 of the method for preparing a white oil hydrogenation catalyst, the gel is dried under vacuum at 60-120°C for 6-24 hours, more preferably at 110°C for 10 hours; and the gel is calcined at 400-600°C for 3-5 hours, more preferably at 500°C for 3 hours. This calcination removes impurities from the material, unclogs the active pore structure, increases the specific surface area of ​​the material, and improves the performance of the resulting amorphous silica-alumina material and amorphous silica-alumina-based support, thereby enhancing the catalytic activity of the white oil hydrogenation catalyst.

[0044] The above-mentioned method for preparing polystyrene white oil, preferably, in S1 of the method for preparing a white oil hydrogenation catalyst, the method for preparing the aluminum sol comprises: mixing and stirring pseudo-boehmite or alumina powder, nitric acid and water at a temperature of 40-90°C to obtain an aluminum sol; wherein the molar ratio of nitric acid to deionized water is 0.1-0.5:1, more preferably 0.3:1, and the mass ratio of deionized water to pseudo-boehmite is 5-50:1, more preferably 10:1.

[0045] The above-mentioned method for preparing polystyrene white oil, preferably, in S1 of the method for preparing a white oil hydrogenation catalyst, the method for preparing the silica sol comprises: mixing and stirring an ethanol solution of tetraethyl orthosilicate or ethyl orthosilicate with a mixed solution of ethanol, nitric acid, and water at room temperature of 20-30°C for 10-30 minutes to obtain a silica sol; wherein the molar ratio of tetraethyl orthosilicate or ethyl orthosilicate to ethanol in the ethanol solution of tetraethyl orthosilicate or ethyl orthosilicate is 1-10:1, preferably 5:1, the molar ratio of water, nitric acid, and ethanol in the mixed solution is 5-20:0.5-5:1, preferably 10:1.3:1, and the molar ratio of the ethanol solution of tetraethyl orthosilicate or ethyl orthosilicate to the mixed solution is 1.2-12.3.

[0046] S1 of the white oil hydrogenation catalyst preparation method specifically includes the following steps:

[0047] Aluminum sol was prepared by mixing pseudo-boehmite, deionized water, and nitric acid and stirring at 75°C for 2 hours, wherein the mass ratio of pseudo-boehmite to deionized water was 1:10, and the molar ratio of nitric acid to deionized water was 0.3:1;

[0048] The silica sol is prepared by mixing an ethanol solution of tetraethyl orthosilicate or ethyl orthosilicate with a mixed solution of deionized water, nitric acid, and ethanol at room temperature for 30 minutes, wherein the molar ratio of tetraethyl orthosilicate or ethyl orthosilicate to ethanol in the ethanol solution of tetraethyl orthosilicate or ethyl orthosilicate is 5:1, and the molar ratio of deionized water, nitric acid, and ethanol in the mixed solution of deionized water, nitric acid, and ethanol is 10:1.3:1;

[0049] Silica sol was added to aluminum sol and stirred vigorously to form a gel. The gel was vacuum dried at 110° C. for 10 hours (vacuum degree was less than 80 mmHg), and then calcined at 500° C. for 3 hours to obtain an amorphous silicon-aluminum material.

[0050] In step S1 of the white oil hydrogenation catalyst preparation method, the catalyst gradually gels through hydrolysis and polycondensation to form alumina sol and silica sol, respectively. The two are then uniformly mixed to form an ASA sol. This sol is then aged, washed, dried, formed, and calcined to form an amorphous silica-alumina material. The control of the synthesis conditions for the silica-alumina sol and the carrier composite modification method are the primary factors influencing the performance of the white oil hydrogenation catalyst.

[0051] In the above-mentioned method for preparing polystyrene white oil, preferably, in S2 of the method for preparing the white oil hydrogenation catalyst, the mass ratio of boric acid to the amorphous silica-alumina carrier is 0.01-0.03:1, preferably 0.02:1.

[0052] In the above-mentioned method for preparing polystyrene white oil, preferably, in step S2 of the method for preparing the white oil hydrogenation catalyst, the calcination temperature is 450-550°C, the calcination time is 3-8 hours, and more preferably, the rate of heating to the calcination temperature is 1°C / min.

[0053] In the above-mentioned method for preparing polystyrene white oil, preferably, in step S3 of the method for preparing the white oil hydrogenation catalyst, the mass ratio of urea to the boric acid-modified support is 0.35-0.45:1, preferably 0.4:1. Urea modification can significantly improve the dispersion of active metals in the amorphous silica-alumina-based support, thereby enhancing the activity of the white oil hydrogenation catalyst.

[0054] In the above-mentioned method for preparing polystyrene white oil, preferably, in S3 of the method for preparing the white oil hydrogenation catalyst, the particle size of the ground mixed particles is 240-320 mesh.

[0055] In the above-mentioned method for preparing polystyrene white oil, preferably, in step S3 of the method for preparing the white oil hydrogenation catalyst, the first calcination temperature is 120-180°C for 2-5 hours, and the second calcination temperature is 280-320°C for 2-5 hours. More preferably, the heating rate to both the first and second calcination temperatures is 1°C / min. More preferably, the washing liquid used for washing the calcined product is water and alcohol.

[0056] In the above-mentioned method for preparing polystyrene white oil, preferably, in S4 of the method for preparing the white oil hydrogenation catalyst, the platinum source is selected from tetraammineplatinum nitrate and / or chloroplatinic acid, and the palladium source is selected from palladium nitrate and / or palladium acetate.

[0057] In the above-mentioned method for preparing polystyrene white oil, preferably, in S4 of the method for preparing the white oil hydrogenation catalyst, the drying conditions include: drying at 80-120°C for 4-8 hours; and the calcination conditions include: calcining at 320-360°C for 5-8 hours. More preferably, the drying conditions include: drying at 100°C for 5 hours; and the calcination conditions include: calcining at 350°C for 6 hours.

[0058] The present invention also provides a polystyrene white oil prepared by the preparation method of the polystyrene white oil claimed in claim 1.

[0059] The above-mentioned polystyrene white oil preferably has a viscosity of 60-75 mm at 40°C. 2 / S.

[0060] The preparation method of the polystyrene white oil of the present invention adopts a three-stage hydrogenation process, through hydrogenation and fractionation operations, by mixing at least one of intermediate base isomerized oil or naphthenic isomerized oil with paraffin base isomerized oil, and using the above white oil hydrogenation catalyst to prepare a polystyrene white oil with a viscosity range of 60-75mm at 40°C.2 / S polystyrene white oil has a water-white appearance and excellent oxidation stability and light and heat stability. The product's polycyclic aromatic hydrocarbons have a UV absorbance of <0.1, carbonized substances easily pass through, and the color is +30. These properties ensure the food-grade quality of the white oil. Adding it to polystyrene particles has a good effect in preventing yellowing.

[0061] In terms of performance, the polystyrene white oil product produced by the present invention has a naphthenic carbon content greater than 32, demonstrating good compatibility with polystyrene. It also has a low pour point and meets the requirements for solid paraffin wax. Its flash point is greater than 240°C, demonstrating excellent safety. Its 5% point carbon number is greater than 22, resulting in minimal evaporation loss. All other indicators meet the standards for polystyrene white oil.

[0062] The preparation method of the present invention can prepare high-quality polystyrene white oil, increase the output of white oil, improve the economic benefits of the enterprise, and reduce production costs and device energy consumption.

[0063] The technical solution provided by the present invention has the following beneficial effects:

[0064] The present invention uses the heavy fraction of the compounded hydroisomerization oil as the feed oil and adopts a boric acid urea composite modified white oil hydrogenation catalyst, which has a good effect on the deep aromatic saturation of the isomerized oil with branched polycyclic aromatic hydrocarbons. In addition, the present invention adopts a three-stage hydrogenation process. After hydrogenation and fractionation operations, the polystyrene white oil prepared by mixing intermediate base or naphthenic isomerized oil with paraffinic isomerized oil has high viscosity and excellent oxidative stability and photothermal stability. All indicators meet the standards for polystyrene white oil. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Figure 1 The wide-angle XRD spectra of the amorphous silicon aluminum material (ASA) and the modified amorphous silicon aluminum-based support (BN-ASA) of Example 1;

[0066] Figure 2 This is the N2- adsorption-desorption isotherm of the boric acid-urea modified amorphous silica-alumina support (BN-ASA support) prepared in Example 1;

[0067] Figure 3 This is the pore size distribution diagram of the boric acid-urea modified amorphous silica-alumina support (BN-ASA support) prepared in Example 1;

[0068] Figure 4 This is a process flow chart for producing polystyrene white oil in Example 9.

[0069] Description of Figure Numbers:

[0070] 1-hydrogenation pre-refining reactor, 2-stripping tower, 3-hydroisomerization reactor, 4-fractionation tower, 5-white oil hydrogenation reactor. DETAILED DESCRIPTION

[0071] In order to have a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention is now described in detail below, but it should not be understood as limiting the scope of implementation of the present invention.

[0072] The raw materials used in the embodiments of the present invention are as follows:

[0073] Raw oil: Intermediate base distillate oil and naphthenic distillate oil are both from refineries, and paraffin base oil uses Daqing Refining and Chemical's second-line distillate oil.

[0074] Catalyst source and main physical properties:

[0075] The hydroprocessing pre-refining catalyst uses the lubricating oil pretreatment catalyst PHT-01 from the Petrochemical Research Institute, which has a light green clover-like appearance. The active component is a non-precious metal. The catalyst has a BET specific surface area of ​​165m 2 / g, pore volume 0.32cm 3 / g, strength ≥100N / cm.

[0076] The hydroisomerization catalyst uses the PIC series catalyst from the Petrochemical Research Institute, which has a gray clover appearance. The active components are Pt and Pd, and the BET specific surface area of ​​the catalyst component is 186m 2 / g, pore volume 0.25cm 3 / g, strength ≥100N / cm.

[0077] Example 1

[0078] This embodiment provides a white oil hydrogenation catalyst, the preparation method of which comprises the following steps:

[0079] Step 1: Weigh 102 g of pseudo-boehmite, dissolve 1049 g of nitric acid in 1000 g of deionized water, add the pseudo-boehmite to the nitric acid aqueous solution, and stir mechanically at 75° C. until the solution is homogeneous to obtain an aluminum sol;

[0080] Step 2: 180g of deionized water and 60ml of dilute nitric acid were dissolved in 46g of anhydrous ethanol in sequence to obtain solution A; 299g of tetraethyl orthosilicate was slowly added dropwise to 10.5g of the ethanol solution, and stirred to fully dissolve them to obtain solution B; Sol A was added to Solution B under vigorous stirring at a rate of 20ml / min, and stirring was continued for 30min to obtain silica sol;

[0081] Step 3: Add the silica sol prepared in step 2 dropwise to the aluminum sol prepared in step 1, maintain the water bath temperature at 75°C, stir while dropping, and the mechanical stirring speed is 400 r / min; continue stirring for 30 minutes after the addition is completed, and vacuum dry the obtained mixed sol at 110°C for 10 hours, and then calcine at 500°C for 3 hours to obtain an amorphous silica-alumina material, recorded as ASA material;

[0082] Step 4: Prepare the amorphous silica-alumina material prepared in step 3 into a catalyst support: take 50g of the amorphous silica-alumina support, prepare 105ml of 0.16mol / L boric acid solution, impregnate the amorphous silica-alumina material with equal volume of boric acid solution, then place it in an oven to dry at 60℃ for 24h, and then place it in a muffle furnace to calcine at 500℃ for 3h to obtain a boric acid modified support, which is recorded as B-ASA support;

[0083] Step 5: 50 g of the boric acid-modified support prepared in step 4 was mixed with 20 g of urea and ground into 300 mesh. The mixture was placed in a sealed crucible and dried at 150°C for 2 h, and then calcined at 300°C for 2 h to obtain an amorphous silica-alumina support modified with boric acid and urea, which was designated as BN-ASA support.

[0084] Step 6: Dissolve 0.265g of chloroplatinic acid in 10g of deionized water to form a solution, and dissolve 0.379g of palladium nitrate in 10g of deionized water to form a solution. Mix the two metal solutions and add water to the mixed solution until the mass reaches 40g. Use the solution to vacuum impregnate 50g of the amorphous silica-aluminum-based support (BN-ASA support) obtained in step 5, and ultrasonically disperse it for 30min. Dry it at 100°C for 5h, calcine it at 350°C for 6h, and then cool it to room temperature to obtain an amorphous silica-aluminum-based white oil hydrogenation catalyst loaded with Pt-Pd.

[0085] The weight percentages of the components in the white oil hydrogenation catalyst prepared in this example are SiO2:Al2O3:Pt:Pd=39:60.4:0.25:0.35. This catalyst is designated as Cat-1.

[0086] Figure 1 These are the wide-angle XRD results of the amorphous silica-alumina material (ASA) of Example 1 and the modified amorphous silica-alumina-based carrier (BN-ASA).

[0087] Phase analysis of the synthesized samples was performed using a Rigaku Corporation 2500 X-ray diffractometer. The scanning range was 5-75°. Experimental conditions were: Cu Kα radiation, tube voltage 50 kV, tube current 20 mA, scanning speed 3° / min, and step size 0.02°.

[0088] Depend on Figure 1It can be seen that the amorphous silica-alumina material (ASA) of Example 1 has a diffuse peak of silica at 20°-30°, characteristic peaks of pseudo-boehmite at 28°, 38°, and 48°, and a characteristic peak of γ-alumina at 67°. It can be seen from the XRD spectrum that the carrier is amorphous silica-alumina powder; the amorphous silica-alumina-based (BN-ASA) modified with boric acid and then with urea still has the characteristic peaks of amorphous silica-alumina powder. Compared with before modification, the characteristic peak position, peak height and peak intensity remain basically unchanged, and the carrier after modification is also in an amorphous silica-alumina state.

[0089] Figure 2 The N2- adsorption-desorption isotherm of the amorphous silicon-aluminum-based carrier (BN-ASA) of Example 1 is shown in FIG. Figure 2 It can be seen that the boric acid-urea modified amorphous silica-alumina support (BN-ASA) in Example 1 has a type IV adsorption-desorption isotherm and an H1-type hysteresis loop, indicating that this material has a relatively concentrated mesoporous channel distribution.

[0090] Figure 3 The pore size distribution diagram of the amorphous silica-alumina-based carrier (BN-ASA) of Example 1. Figure 3 It can be seen that the boric acid-urea modified amorphous silica-alumina support (BN-ASA) in Example 1 has broad pores and a concentrated pore size distribution.

[0091] Example 2

[0092] This example provides a white oil hydrogenation catalyst, the preparation method of which is the same as that of Example 1, except that in step 1, low-sodium activated alumina is used instead of pseudo-boehmite to prepare the aluminum sol. The catalyst prepared in this example is designated Cat-2.

[0093] Example 3

[0094] This example provides a white oil hydrogenation catalyst. The preparation method is the same as that of Example 1, except that in step 2, 236 g of tetraethyl orthosilicate is used instead of ethyl orthosilicate to prepare a silica sol. The catalyst prepared in this example is designated Cat-3.

[0095] Example 4

[0096] This example provides a white oil hydrogenation catalyst. The preparation method is the same as that of Example 1, except that in step 4, a mass ratio of boric acid to amorphous silica-alumina support is 0.01:1. 50 g of amorphous silica-alumina is prepared with 101 ml of a 0.08 mol / L boric acid solution. The amorphous silica-alumina is then impregnated with an equal volume of the boric acid solution. The catalyst is then dried and calcined to produce a boric acid-modified support. The catalyst prepared in this example is designated Cat-4.

[0097] Example 5

[0098] This example provides a white oil hydrogenation catalyst. The preparation method is the same as that of Example 1, except that in step 4, a mass ratio of boric acid to amorphous silica-alumina support is 0.03:1. 50 g of amorphous silica-alumina is prepared with 101 ml of a 0.24 mol / L boric acid solution. The amorphous silica-alumina is then impregnated with an equal volume of the boric acid solution. The catalyst is then dried and calcined to produce a boric acid-modified support. The catalyst prepared in this example is designated Cat-5.

[0099] Example 6

[0100] This example provides a white oil hydrogenation catalyst. Its preparation method is the same as that of Example 1, except that in step 5, the mass ratio of urea to the boric acid-modified support is 0.35:1. 50 g of the boric acid-modified ASA support and 17.5 g of urea are mixed and ground, dried, and calcined to produce a boric acid-urea-modified amorphous silica-alumina support. The catalyst prepared in this example is designated Cat-6.

[0101] Example 7

[0102] This embodiment provides a white oil hydrogenation catalyst, the preparation method of which is the same as that of Example 1, except that: in step 5, the mass ratio of urea to the boric acid-modified support is 0.45:1, 50 g of the boric acid-modified ASA support is mixed with 22.5 g of urea and ground, and then dried and calcined to obtain a urea-modified B-NASA support.

[0103] The catalyst prepared in this example is designated as Cat-7.

[0104] Comparative Example 1

[0105] This comparative example provides a hydrotreating catalyst, the preparation method of which is the same as that of Example 1, except that steps 1 to 3 in Example 1 are replaced by the method disclosed in Example 1 of CN201310499346.6 specification to prepare amorphous silicon-aluminum material.

[0106] The catalyst prepared in this comparative example is recorded as Cat-8.

[0107] Comparative Example 2

[0108] This comparative example provides a hydrotreating catalyst, the preparation method of which is the same as that of Example 1, except that step 4 in Example 1 is not performed in this comparative example, that is, 50 g of the amorphous silicon-alumina material of Example 1 is modified with urea to prepare a carrier, which is recorded as N-ASA carrier.

[0109] The catalyst prepared in this comparative example is recorded as Cat-9.

[0110] Comparative Example 3

[0111] This comparative example provides a hydrorefining catalyst, the preparation method of which is the same as that of Example 1, except that: this comparative example does not perform step five in Example 1, that is, 50g of the amorphous silicon-alumina material of Example 1 is modified with boric acid to prepare a carrier, which is recorded as B-ASA carrier.

[0112] The catalyst prepared in this comparative example is recorded as Cat-10.

[0113] Comparative Example 4

[0114] This comparative example provides a hydrotreating catalyst, the preparation method of which is the same as that of Example 1, except that steps 4 and 5 of Example 1 are not performed in this comparative example, that is, the active metal is directly loaded on the ASA material of Example 1 to prepare the catalyst.

[0115] The catalyst prepared in this comparative example is recorded as Cat-11.

[0116] Example 8

[0117] This embodiment provides four heavy fractions of hydroisomerized oil, and the preparation methods thereof are as follows:

[0118] (1) Crude oil:

[0119] The raw oils used in this embodiment include intermediate base minus fourth-line distillate oil (1#), cycloalkyl minus third-line distillate oil 1 (2#), cycloalkyl minus third-line distillate oil 2 (3#), and paraffin base minus second-line distillate oil (4#). The product properties are shown in Table 1.

[0120] Table 1 Main properties of four raw oils

[0121]

[0122] As shown in Table 1, naphthenic oils are characterized by high density, high sulfur and nitrogen content, low wax content, high viscosity, and a low viscosity index. Paraffinic oils, on the other hand, are easy to process, have low viscosity, and low naphthenic content. Intermediate base oils have a viscosity and naphthenic content between the two, and high sulfur and nitrogen content.

[0123] (2) Hydrogenation pre-refining:

[0124] The four raw oils, namely, the intermediate base minus four-line distillate oil (1#), the naphthenic base minus three-line distillate oil 1 (2#), the naphthenic base minus three-line distillate oil 2 (3#), and the paraffinic base minus two-line distillate oil (4#), are subjected to hydrogenation pre-refining reaction to obtain four hydrogenated pre-refined oils, namely, the intermediate base minus four-line refined oil, the naphthenic base minus three-line refined oil 1, the naphthenic base minus three-line refined oil 2, and the paraffinic base minus two-line refined oil;

[0125] The reaction conditions for the hydrogenation pre-refining of the intermediate base minus four-line distillate (1#) and the naphthenic base minus three-line distillate 2 (3#) are as follows: reaction pressure 15 MPa, reaction temperature 380°C, space velocity 0.5 h -1 , hydrogen-oil ratio 1000:1;

[0126] The reaction conditions for the hydro-refining of cycloalkyl-minus-three-line distillate oil 1 (2#) are as follows: reaction pressure 16 MPa, reaction temperature 385°C, space velocity 0.5 h -1 , hydrogen-oil ratio 1000:1;

[0127] The reaction conditions for the hydrogenation pre-refining of paraffin-based second-line distillate oil (4#) are: reaction pressure 12.5MPa, reaction temperature 375℃, space velocity 0.85h -1 , hydrogen-to-oil ratio 800:1.

[0128] The product properties of the four hydrogenated pre-refined oils obtained in this step (intermediate base minus four-line refined oil, naphthenic base minus three-line refined oil 1, naphthenic base minus three-line refined oil 2, paraffin base minus two-line refined oil) are shown in Table 2.

[0129] Table 2 Some properties of four hydrorefined oils

[0130]

[0131] (3) Hydroisomerization

[0132] The four kinds of hydrogenated pre-refined oils (intermediate base minus four-line refined oil, naphthenic base minus three-line refined oil 1, naphthenic base minus three-line refined oil 2, paraffinic base minus two-line refined oil) are respectively subjected to hydrogenation isomerization reaction to obtain hydrogenated isomerized product oils (intermediate base minus four-line isomerized product oil, minus three-line oil 1 isomerized product oil, minus three-line oil 2 isomerized product oil, paraffinic base minus two-line isomerized product oil), and then the hydrogenated isomerized product oils are respectively fractionated to obtain heavy fractions of the hydrogenated isomerized product oils (380-480° C. fraction of intermediate base minus four-line isomerized product oil, >360° C. fraction of minus three-line oil 1 isomerized product oil, >360° C. fraction of minus three-line oil 2 isomerized product oil, 380-480° C. fraction of paraffinic base minus two-line isomerized product oil);

[0133] The hydroisomerization reaction conditions of the intermediate base minus four-line refined oil are: reaction pressure 15MPa, reaction temperature 350℃, space velocity 1.2h -1 , hydrogen-oil ratio 500:1;

[0134] The hydroisomerization reaction conditions of cycloalkyl-refined oil 1 are as follows: reaction pressure 15 MPa, reaction temperature 290 °C, space velocity 1.0 h -1 , hydrogen-oil ratio 800:1;

[0135] The hydroisomerization reaction conditions of cycloalkyl-refined oil 2 are as follows: reaction pressure 15 MPa, reaction temperature 350 ° C, space velocity 1.0 h -1 , hydrogen-oil ratio 800:1;

[0136] The hydroisomerization reaction conditions of paraffin-based refined oil are as follows: reaction pressure 12 MPa, reaction temperature 330℃, space velocity 1.2h -1 , hydrogen-to-oil ratio 350:1.

[0137] The product properties of the heavy fractions of the four hydroisomerized oils obtained in this step are shown in Table 3.

[0138] Table 3 Product properties of the heavy fraction of hydroisomerized oil

[0139]

[0140] Example 9

[0141] This embodiment provides a method for preparing polystyrene white oil, which is as follows:

[0142] The 380-480° C. fraction of the paraffin-based oil minus two-line isomerization product obtained in Example 8 and the 380-520° C. fraction of the intermediate-based oil minus four-line isomerization product were mixed to obtain feed oil, wherein the mass fraction of the 380-480° C. fraction of the paraffin-based oil minus two-line isomerization product in the feed oil was 6.5%, and the mass fraction of the 380-520° C. fraction of the intermediate-based oil minus four-line isomerization product was 93.5%;

[0143] Then, the feed oil was subjected to a white oil hydrogenation reaction under the catalysis of the white oil hydrogenation catalyst Cat-1 of Example 1, wherein the reaction conditions of the white oil hydrogenation reaction were: reaction pressure 15 MPa, reaction temperature 230°C, space velocity 0.6 h -1 , hydrogen-to-oil ratio 500:1, thereby preparing a polystyrene white oil product with a product liquid yield of 96%, an aromatic hydrocarbon content of 0.08%, and a kinematic viscosity of 63mm at 40°C. 2 / S.

[0144] The properties of the obtained polystyrene white oil product are shown in Table 4. The production process of polystyrene white oil product is as follows Figure 4 shown.

[0145] Example 10

[0146] This example provides a method for preparing polystyrene white oil, which is the same as Example 9, except that the catalyst used in this example is the white oil hydrogenation catalyst Cat-2 of Example 2. The properties of the resulting polystyrene white oil product are shown in Table 4.

[0147] Example 11

[0148] This example provides a method for preparing polystyrene white oil, which is the same as Example 9, except that the catalyst used in this example is the white oil hydrogenation catalyst Cat-4 of Example 4. The properties of the resulting polystyrene white oil product are shown in Table 4.

[0149] Example 12

[0150] This example provides a method for preparing polystyrene white oil, which is the same as Example 9, except that the catalyst used in this example is the white oil hydrogenation catalyst Cat-5 of Example 5. The properties of the resulting polystyrene white oil product are shown in Table 4.

[0151] Comparative Example 5

[0152] This comparative example provides a method for preparing polystyrene white oil, which is the same as Example 9, except that the catalyst used in this example is the hydrogenation catalyst Cat-8 of Comparative Example 1. The properties of the obtained polystyrene white oil product are shown in Table 4.

[0153] Table 4 Main index test results of PS white oil prepared by mixing 1# and 4# isomerized oil

[0154]

[0155] As can be seen from Table 4, the aromatic saturation effects of Cat-1 and Cat-2 on the intermediate base mixed oil are better than those of Comparative Example 1, and the UV absorbance meets the requirement of <0.1.

[0156] Example 13

[0157] This embodiment provides a method for preparing polystyrene white oil, which is as follows:

[0158] The 360-500°C fraction of the cycloalkyl-3-line oil-1 isomerized product oil obtained in Example 8 and the 380-480°C fraction of the paraffin-2-line oil isomerized product oil were mixed to obtain a feed oil, wherein the mass fraction of the 360-500°C fraction of the cycloalkyl-3-line oil-1 isomerized product oil in the feed oil was 83%, and the mass fraction of the 380-480°C fraction of the paraffin-2-line oil isomerized product oil was 17%;

[0159] Then, the feed oil was subjected to a white oil hydrogenation reaction under the catalysis of the white oil hydrogenation catalyst Cat-1 of Example 1, wherein the reaction conditions of the white oil hydrogenation reaction were: reaction pressure 15 MPa, reaction temperature 230°C, space velocity 0.6 h -1 , hydrogen-to-oil ratio 500:1, thereby preparing polystyrene white oil product, the product liquid yield is 97%, aromatic content is 0.06%, and the kinematic viscosity at 40℃ reaches 74mm 2 / S.

[0160] The properties of the obtained polystyrene white oil product are shown in Table 5.

[0161] Example 14

[0162] This example provides a method for preparing polystyrene white oil, which is the same as Example 13, except that the catalyst used in this example is the white oil hydrogenation catalyst Cat-3 of Example 3. The properties of the resulting polystyrene white oil product are shown in Table 5.

[0163] Comparative Example 6

[0164] This comparative example provides a method for preparing polystyrene white oil, which is the same as Example 13, except that the catalyst used in this comparative example is the white oil hydrogenation catalyst Cat-9 described in Comparative Example 2. The properties of the resulting polystyrene white oil product are shown in Table 5.

[0165] Comparative Example 7

[0166] This comparative example provides a method for preparing polystyrene white oil, which is the same as Example 13, except that the catalyst used in this comparative example is the white oil hydrogenation catalyst Cat-11 described in Comparative Example 4. The properties of the resulting polystyrene white oil product are shown in Table 5.

[0167] Table 5 Main index test results of PS white oil prepared by mixing 2# and 4# isomerized oil

[0168]

[0169] As can be seen from Table 5, the aromatic saturation effects of Cat-1 and Cat-3 on cycloalkyl mixed oil are higher than those of Comparative Examples 2 and 4, and the ultraviolet absorbance meets the requirement of <0.1.

[0170] Example 15

[0171] This embodiment provides a method for preparing polystyrene white oil, which is as follows:

[0172] The 360-500°C fraction of the cycloalkyl-3-line oil-2 isomerized product oil obtained in Example 8 and the 380-480°C fraction of the paraffin-2 isomerized product oil were mixed to obtain a feed oil, wherein the mass fraction of the 360-500°C fraction of the cycloalkyl-3-line oil-2 isomerized product oil in the feed oil was 88%, and the mass fraction of the 380-480°C fraction of the paraffin-2 isomerized product oil was 12%;

[0173] Then, the feed oil was subjected to a white oil hydrogenation reaction under the catalysis of the white oil hydrogenation catalyst Cat-1 of Example 1, wherein the reaction conditions of the white oil hydrogenation reaction were: reaction pressure 15 MPa, reaction temperature 230°C, space velocity 0.6 h -1, hydrogen-to-oil ratio 500:1, thereby preparing polystyrene white oil product, the product liquid yield is 97%, aromatic content is 0.03%, and 40℃ kinematic viscosity is 68mm 2 / S.

[0174] The properties of the obtained polystyrene white oil product are shown in Table 6.

[0175] Example 16

[0176] This example provides a method for preparing polystyrene white oil, which is the same as Example 15, except that the catalyst used in this example is the white oil hydrogenation catalyst Cat-2 of Example 2. The properties of the resulting polystyrene white oil product are shown in Table 6.

[0177] Example 17

[0178] This example provides a method for preparing polystyrene white oil, which is the same as Example 15, except that the catalyst used in this example is the white oil hydrogenation catalyst Cat-6 of Example 6. The properties of the resulting polystyrene white oil product are shown in Table 6.

[0179] Example 18

[0180] This example provides a method for preparing polystyrene white oil, which is the same as Example 15, except that the catalyst used in this example is the white oil hydrogenation catalyst Cat-7 of Example 7. The properties of the resulting polystyrene white oil product are shown in Table 6.

[0181] Comparative Example 8

[0182] This comparative example provides a method for preparing polystyrene white oil, which is the same as Example 15, except that the catalyst used in this comparative example is the white oil hydrogenation catalyst Cat-10 described in Comparative Example 3. The properties of the resulting polystyrene white oil product are shown in Table 6.

[0183] Table 6 Main index test results of PS white oil prepared from mixed isomerized oils 3# and 4#

[0184]

[0185]

[0186] As shown in Table 6, Cat-1, Cat-2, Cat-6, and Cat-7 all achieved higher aromatic saturation effects on 3# cycloalkyl mixed oil than Comparative Example 3, with UV absorbances below 0.1. However, the aromatic saturation effects of Cat-6 and Cat-7 were lower than those of Cat-1. As shown in Tables 4-6, Cat-1 through Cat-7 all achieved higher hydrogenation effects on white oil than Comparative Examples 1, 2, 3, and 4. The UV absorbances of the white oil products after hydrogenation and dearomatization with Cat-1 through Cat-7 catalysts were all below 0.1, meeting the required specifications.

Claims

1. A method for preparing polystyrene white oil, comprising the following steps: The heavy fraction of the hydroisomerization oil is subjected to a white oil hydrogenation reaction under the action of a white oil hydrogenation catalyst to obtain polystyrene white oil; in, The heavy fraction of the hydroisomerization oil is a combination of a heavy fraction with a temperature of >380°C of a paraffin-based oil minus two-line isomerization product and a heavy fraction with a temperature of >380°C of an intermediate-based oil minus four-line isomerization product, or a heavy fraction with a temperature of >380°C of a paraffin-based oil minus two-line isomerization product and a heavy fraction with a temperature of >360°C of a naphthenic oil minus three-line isomerization product; The white oil hydrogenation catalyst comprises an amorphous silica-alumina-based support and an active metal, wherein the active metal comprises platinum and palladium; The white oil hydrogenation catalyst is prepared by the following method: S1: stirring and mixing silica sol and alumina sol to form a gel, and drying and calcining the gel to obtain an amorphous silica-alumina material; S2: impregnating an amorphous silicon-alumina material with an equal volume of boric acid solution, removing the solid after impregnation, drying it, and calcining it to obtain a boric acid-modified support; S3: mixing urea and the boric acid modified support and grinding them, calcining the obtained mixed particles in a closed state in two stages, and washing them to obtain an amorphous silica-alumina-based support; S4: Immersing an equal volume of the amorphous silica-alumina-based support in a mixed solution containing a platinum source and a palladium source. After the impregnation is completed, the solid is taken out and dried and calcined to obtain the white oil hydrogenation catalyst.

2. The method for preparing polystyrene white oil according to claim 1, wherein The heavy fraction of the hydroisomerization oil is a combination of a fraction of paraffin-based minus two-line isomerization oil with a temperature of >380°C and ≤480°C and a fraction of intermediate-based minus four-line isomerization oil with a temperature of >380°C and ≤520°C, or a combination of a fraction of paraffin-based minus two-line isomerization oil with a fraction of >380°C and ≤480°C and a fraction of cycloalkyl-based minus three-line isomerization oil with a temperature of >360°C and ≤500°C.

3. The method for preparing polystyrene white oil according to claim 1, wherein: The heavy fraction of the hydroisomerization oil is a combination of a fraction with a temperature of >380°C and ≤480°C of a paraffin-based minus two-line isomerization oil and a fraction with a temperature of >380°C and ≤520°C of an intermediate-based minus four-line isomerization oil in a mass ratio of 1:12-15.

4. The method for preparing polystyrene white oil according to claim 1, wherein: The heavy fraction of the hydroisomerization oil is a combination of a fraction of paraffin-based minus two-line isomerization oil with a temperature of >380°C and ≤480°C and a fraction of naphthenic-based minus three-line isomerization oil with a temperature of >360°C and ≤500°C in a mass ratio of 1:4-8.

5. The method for preparing polystyrene white oil according to claim 1, wherein: The reaction conditions for white oil hydrogenation include: reaction pressure of 12-16 MPa, reaction temperature of 210-240°C, volume space velocity of 0.5-1.0 h -1 , the hydrogen-to-oil ratio is 300-600:

1.

6. The method for preparing polystyrene white oil according to claim 5, wherein: The reaction conditions for white oil hydrogenation include: reaction pressure 15 MPa, reaction temperature 230°C, volume space velocity 0.6 h -1 , hydrogen-to-oil ratio 500:

1.

7. The method for preparing polystyrene white oil according to claim 1, wherein: Before the white oil hydrogenation reaction, the polystyrene white oil preparation method further comprises reducing the white oil hydrogenation catalyst; the reduction conditions include: hydrogen pressure of 1.0-2.0 MPa, reduction temperature of 200-400° C., and reduction time of 10-16 hours.

8. The method for preparing polystyrene white oil according to claim 1, wherein: The heavy fraction of the hydroisomerization oil is prepared by the following method: The raw oil is subjected to hydrogenation pre-refining to obtain hydrogenation pre-refined oil respectively; the hydrogenation pre-refined oil is subjected to hydrogenation isomerization to obtain hydrogenation isomerization product oil respectively; Performing fractional distillation to obtain a heavy fraction of the hydroisomerization oil; The reaction conditions for hydrogenation pre-refining include: reaction pressure of 12-17 MPa, reaction temperature of 350-390°C, volume space velocity of 0.3-1.0 h -1 , hydrogen-to-oil ratio is 300-1000:1; The hydroisomerization reaction conditions include: reaction pressure of 8-16 MPa, reaction temperature of 320-370°C, volume space velocity of 0.6-1.5h -1 , hydrogen-to-oil ratio 300-800:

1.

9. The method for preparing polystyrene white oil according to claim 8, wherein: The raw material oil is any one of naphthenic base minus third-line distillate oil, intermediate base minus fourth-line distillate oil, and paraffin base minus second-line distillate oil.

10. The method for preparing polystyrene white oil according to claim 1, wherein: Based on the total mass of the white oil hydrogenation catalyst, the content of platinum element is 0.1-0.4wt%, and the content of palladium element is 0.2-0.4wt%.

11. The method for preparing polystyrene white oil according to claim 1, wherein The specific area of ​​the amorphous silica-alumina-based carrier is 371-442 m 2 ·g -1 , pore diameter is 11.4-13.6nm, pore volume is 1.22-1.56cm 3 ·g -1 .

12. The method for preparing polystyrene white oil according to claim 1, wherein: The mass ratio of the silicon source calculated as SiO2 to the aluminum source calculated as Al2O3 in S1 is 3:7-5:

5.

13. The method for preparing polystyrene white oil according to claim 1, wherein: The preparation method of the aluminum sol described in S1 includes: mixing and stirring pseudo-boehmite or alumina powder, nitric acid and deionized water at a temperature of 40-90° C. to obtain aluminum sol; wherein the molar ratio of nitric acid to deionized water is 0.1-0.5, and the mass ratio of deionized water to pseudo-boehmite is 5-50.

14. The method for preparing polystyrene white oil according to claim 1, wherein: The preparation method of the silica sol described in S1 includes: mixing an ethanol solution of tetraethyl orthosilicate with a mixed solution of ethanol, nitric acid, and water at a temperature of 20-30°C and stirring for 10-30 minutes to obtain a silica sol; wherein the molar ratio of tetraethyl orthosilicate to ethanol in the ethanol solution of tetraethyl orthosilicate is 1-10:1, the molar ratio of ethanol, nitric acid, and water in the mixed solution is 1:0.5-5:5-20, and the molar ratio of the ethanol solution of tetraethyl orthosilicate to the mixed solution is 1.2-12.

3.

15. The method for preparing polystyrene white oil according to claim 1, wherein: The mass ratio of boric acid to amorphous silica-alumina support in S2 is 0.01-0.03:

1.

16. The method for preparing polystyrene white oil according to claim 1, wherein: The mass ratio of urea to boric acid modified support in S3 is 0.35-0.45:

1.

17. The method for preparing polystyrene white oil according to claim 1, wherein: In S3, the first stage roasting temperature is 120-180°C, and the roasting time is 2-5 hours; the second stage roasting temperature is 280-320°C, and the roasting time is 2-5 hours.

18. The method for preparing polystyrene white oil according to claim 1, wherein: The platinum source in S4 is selected from tetraammineplatinum nitrate and / or chloroplatinic acid, and the palladium source is selected from palladium nitrate and / or palladium acetate.

19. The method for preparing polystyrene white oil according to claim 1, wherein: At 40°C, the viscosity of the polystyrene white oil is 60-75 mm 2 / S.

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