Method for preparing low aromatic transformer oil by medium pressure hydrogenation, Class I transformer oil base oil and Class I transformer oil

Abstract

The present invention provides a method for preparing low-aromatic transformer oil by medium-pressure hydrogenation, a Class I transformer oil base oil and a Class I transformer oil, and relates to the technical field of transformer oil. The method comprises the following steps: (1) mixing cycloalkyl and paraffin-based mixed oil with hydrogen, and performing hydrogenation treatment to obtain hydrogenation treated oil; (2) mixing the hydrogenation treated oil with hydrogen, and performing hydrodecondensation treatment to obtain hydrodecondensation treated oil; (3) mixing the hydrodecondensation treated oil with hydrogen, and performing refining treatment to obtain refined oil; (4) performing gas-liquid separation on the refined oil, performing rectification separation on the separated liquid product, and collecting the fraction with a temperature of more than 260°C to obtain transformer oil base oil. The transformer oil produced by the present invention has excellent carbon structure, antioxidant performance, solubility and low temperature performance.

Description

Technical Field

[0001] The invention relates to the technical field of transformer oil, and in particular to a method for preparing low-aromatic transformer oil by medium-pressure hydrogenation, a Class I transformer oil base oil and a Class I transformer oil. Background Art

[0002] At present, the method of producing transformer oil is generally to produce with a single mineral oil component. The simple paraffin-based and cyclopentane-based transformer oils are used in transformers, which cannot fully take into account the low-temperature flowability, gassing resistance, solubility and oxidation resistance, and cannot reach the ideal balance point. The traditional production process makes the base oil retain some aromatics, which is excellent in gassing resistance and solubility, but the oxidation resistance is not good, and there is the problem of environmental pollution; the hydrogenation production process makes the base oil have significant performance advantages, such as excellent low-temperature performance, oxidation resistance stability and thermal stability, and no environmental pollution. In order to improve the electrical properties and oxidation resistance stability of transformer oil, the current transformer oil hydrogenation production process mainly adopts a high-pressure hydrogenation reaction with a reaction pressure greater than 15.0MPa, and uses a precious metal decondensation catalyst or a precious metal supplementary refining catalyst, which increases the construction cost of the device and reduces the solubility of the transformer oil.

[0003] CN102660363A discloses a transformer oil, which is composed of paraffin-based oil fraction, cycloalkyl oil, alkyl high-boiling products, antioxidants and anti-photosensitive agents. In the transformer oil, the weight percentage of the wax-based oil fraction is 60-75wt%, the weight percentage of the cycloalkyl oil is 19.4-28.5wt%, the weight percentage of the alkyl high-boiling products is 5-10wt%, the weight percentage of the antioxidant is 0.5-1.0wt%, and the weight percentage of the anti-photosensitive agent is 0.1-0.5wt%. The invention also provides a method for preparing transformer oil, which includes adding paraffin-based oil fraction, cycloalkyl oil, and alkyl high-boiling products into a reactor, adding white clay for refining, stirring and refining adsorption at high temperature, adding antioxidant additives and photosensitizers after filtering, and vacuum pump negative pressure of 0.8kPa, and vacuum treatment 1-3 times. The kinematic viscosity of the transformer oil of the invention is 6.5-9.5mm 2 / s, the breakdown voltage is 55-80kV / 2.5mm, but the disadvantages of high cost and low yield are obvious. In addition, the transformer oil base oil in the above patent needs to be refined with white clay for denitrification and decolorization, which brings about the problem of waste white clay treatment, and there are problems of complex process flow and high production cost.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] The object of the present invention is to provide a method for preparing low aromatic transformer oil by medium pressure hydrogenation, Class I transformer oil base oil and Class I transformer oil. The preparation method of low aromatic transformer oil provided by the present invention uses cycloalkyl and paraffin-based mixed oil as raw materials, adopts non-precious metal catalyst, and performs hydrogenation treatment-hydrogenation decondensation-supplementary refining under medium pressure (reaction pressure ≤ 10.0 MPa), and finally performs fractionation process. The method can directly prepare Class I transformer oil base oil, and the transformer oil produced by adding antioxidant has excellent carbon structure, antioxidant performance, solubility and low temperature performance.

[0006] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0007] In a first aspect, the present invention provides a method for preparing low aromatic transformer oil by medium pressure hydrogenation, the method comprising the following steps:

[0008] (1) mixing cycloalkyl and paraffinic mixed oil with hydrogen and performing hydrogenation treatment to obtain hydrogenation product oil;

[0009] (2) mixing the hydrotreated product oil with hydrogen and performing a hydrodecondensation treatment to obtain a hydrodecondensation product oil;

[0010] (3) mixing the hydrodecondensation product oil with hydrogen and performing a refining treatment to obtain a refined product oil;

[0011] (4) separating the refined oil into gas and liquid, separating the separated liquid product by rectification, collecting the fraction with a temperature greater than 260° C., and obtaining transformer oil base oil.

[0012] Preferably, in step (1), the cycloalkyl and paraffinic mixed oil comprises, by mass percentage, 10-40% paraffinic distillate oil and 60-90% cycloalkyl distillate oil.

[0013] Preferably, the paraffinic distillate oil comprises paraffinic normal second line and / or paraffinic minus first line.

[0014] Preferably, the naphthenic distillate oil comprises naphthenic normal second line and / or naphthenic minus first line.

[0015] Preferably, in step (1), the hydroprocessing is carried out under the action of a hydroprocessing catalyst, and the hydroprocessing catalyst is a non-precious metal catalyst.

[0016] Preferably, the hydroprocessing catalyst comprises an active metal oxide and a metal oxide promoter.

[0017] Preferably, the active metal oxide comprises a Group VIII metal oxide, preferably molybdenum trioxide and / or tungsten trioxide.

[0018] Preferably, the metal oxide promoter comprises a Group VIB metal oxide, preferably cobalt trioxide and / or nickel oxide.

[0019] Preferably, in step (1), the reaction pressure of the hydrotreatment is 8.0 to 10.0 MPa.

[0020] Preferably, in step (1), the reaction temperature of the hydrotreatment is 300-370°C.

[0021] Preferably, in step (1), the volume ratio of the cycloalkyl and paraffinic mixed oil to hydrogen is 1:(600-1200).

[0022] Preferably, in step (1), the volume space velocity of the hydroprocessing is 0.2 to 1.0 h -1 .

[0023] Preferably, the hydrodegradation treatment is carried out under the action of a hydrodegradation catalyst, and the hydrodegradation catalyst is a non-precious metal catalyst.

[0024] Preferably, the hydrodegradation catalyst comprises an active metal oxide and a catalyst carrier supporting the active metal oxide.

[0025] Preferably, the active metal oxide comprises Group VIII metal oxide and / or Group VIB metal oxide, preferably nickel oxide and / or tungsten trioxide.

[0026] Preferably, the catalyst carrier comprises a catalyst carrier support having through holes on its surface and a molecular sieve membrane located on the pore surface of the support; wherein the catalyst carrier support having through holes on its surface comprises aluminum oxide and metal oxide additives, and the aluminum oxide and metal oxide additives form a spinel structure.

[0027] Preferably, the metal oxide additive comprises nickel oxide and / or copper oxide.

[0028] Preferably, in step (2), the reaction pressure of the hydrodecondensation treatment is 8.0 to 10.0 MPa.

[0029] Preferably, in step (2), the reaction temperature of the hydrodecondensation treatment is 280-340°C.

[0030] Preferably, in step (2), the volume ratio of the oil generated by the hydrotreatment to hydrogen is 1:(600-1200).

[0031] Preferably, in step (2), the volume space velocity of the hydrodecondensation treatment is 0.8 to 3.0 h -1 .

[0032] Preferably, in step (3), the refining treatment is carried out under the action of a supplementary refining catalyst, and the supplementary refining catalyst is a non-precious metal catalyst.

[0033] Preferably, the post-finishing catalyst comprises an active metal oxide.

[0034] Preferably, the active metal oxide comprises a Group VIII metal oxide and / or a Group VIB metal oxide.

[0035] Preferably, the active metal oxide comprises nickel oxide and / or tungsten trioxide.

[0036] Preferably, in step (3), the reaction pressure of the refining treatment is 8.0 to 10.0 MPa.

[0037] Preferably, in step (3), the reaction temperature of the refining treatment is 290-360°C.

[0038] Preferably, in step (3), the volume ratio of the hydrodegradation product oil to hydrogen is 1:(600-1200).

[0039] Preferably, in step (3), the volume space velocity of the refining treatment is 0.3 to 2.0 h -1 .

[0040] Preferably, in step (4), the pressure of the gas-liquid separation is 6-10 MPa, and the temperature of the gas-liquid separation is 100-220°C.

[0041] Preferably, in step (4), the pressure of the distillation separation is 0.14-0.18 MPa.

[0042] In a second aspect, the present invention provides a Class I transformer oil base oil, wherein the Class I transformer oil base oil is prepared by the method for producing low-aromatic transformer oil by medium-pressure hydrogenation as described in the first aspect.

[0043] Preferably, the sulfur content in the Class I transformer oil base oil is less than 1.0 mg / kg.

[0044] Preferably, the nitrogen content in the Class I transformer oil base oil is less than 1.0 mg / kg.

[0045] Preferably, the CA value of the Class I transformer oil base oil is less than 2.5%.

[0046] Preferably, the pour point of the Class I transformer oil base oil is <-57°C.

[0047] Preferably, the kinematic viscosity of the Class I transformer oil base oil at 40°C is less than 12.0 mm 2 / s.

[0048] Preferably, the kinematic viscosity of the Class I transformer oil base oil at -40°C is less than 2500 mm 2 / s.

[0049] Preferably, the closed cup flash point of the Class I transformer oil base oil is greater than 140°C.

[0050] Preferably, the yield of the Class I transformer oil base oil is >89.0%.

[0051] In a third aspect, the present invention provides a Class I transformer oil, wherein the Class I transformer oil comprises an antioxidant and the Class I transformer oil base oil as described in the second aspect.

[0052] Preferably, the added amount of the antioxidant accounts for 0.05-0.5% of the total mass of the Class I transformer oil, and preferably 0.15-0.25%.

[0053] Preferably, the antioxidant is selected from any one of 2,6-di-tert-butyl-p-cresol, benzothiadiazole antioxidants, phenolic antioxidants or phenolphthalein antioxidants, or a combination of at least two thereof, preferably 2,6-di-tert-butyl-p-cresol.

[0054] Preferably, the aniline point of the Class I transformer oil is 72-78°C.

[0055] Preferably, in the oxidation stability test at 120° C. and 500 h: the total acid value of the Class I transformer oil is less than 0.22 mgKOH / g, the sludge content is less than 0.0038%, and the dielectric loss factor at 90° C. is less than 0.17.

[0056] Compared with the prior art, the present invention has the following beneficial effects:

[0057] (1) The present invention uses cycloalkyl and paraffin mixed distillate oil as raw materials and adopts non-precious metal catalysts under medium pressure (reaction pressure ≤ 10.0 MPa) to directly produce Class I transformer oil base oil through hydrogenation treatment-hydrodecondensation-supplementary refining-fractionation process, meeting the index requirements of GB2536-2011; and avoids the use of high-pressure hydrogenation equipment to increase equipment investment and operation severity. Compared with the existing high-pressure hydrogenation process, it has the characteristics of safe operation and low hydrogen consumption.

[0058] (2) The present invention uses a hydrodegassing catalyst when processing a cycloalkane and paraffin-based mixed oil. The hydrodegassing catalyst pores in the present application only allow straight-chain alkanes and nearly straight-chain isoalkanes in the feedstock oil to enter therein and crack them into small molecular hydrocarbons at their acidic centers. Cycloalkanes are difficult to enter the pores for cracking, and while cracking high pour point alkanes, the ideal components of cycloalkanes are retained, which has the advantages of mild hydrogenation process conditions and high base oil product yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0060] Figure 1 Periodic data graph provided for Test Case 3. DETAILED DESCRIPTION

[0061] Unless otherwise defined herein, scientific and technological terms used in conjunction with the present invention shall have the meanings commonly understood by those of ordinary skill in the art. The meaning and scope of the terms should be clear, however, in the case of any potential ambiguity, the definitions provided herein take precedence over any dictionary or external definitions. In this application, unless otherwise stated, the use of "or" means "and / or". In addition, the use of the term "including" and other forms is non-limiting.

[0062] It should be noted that specific details are described in the following description to facilitate a full understanding of the present invention. However, the present invention can be implemented in a variety of other ways different from those described herein, and those skilled in the art can make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0063] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0064] In a first aspect, the present invention provides a method for preparing low aromatic transformer oil by medium pressure hydrogenation, the method comprising the following steps:

[0065] (1) mixing cycloalkyl and paraffinic mixed oil with hydrogen and performing hydrogenation treatment to obtain hydrogenation product oil;

[0066] (2) mixing the hydrotreated product oil with hydrogen and performing a hydrodecondensation treatment to obtain a hydrodecondensation product oil;

[0067] (3) mixing the hydrodecondensation product oil with hydrogen and performing a refining treatment to obtain a refined product oil;

[0068] (4) separating the refined oil into gas and liquid, separating the separated liquid product by rectification, collecting the fraction with a temperature greater than 260° C., and obtaining transformer oil base oil.

[0069] The present invention uses cycloalkyl and paraffin-based mixed distillate oil as raw materials, adopts non-precious metal catalysts, and can directly produce Class I transformer oil base oil through hydrogenation treatment-hydrodecondensation-supplementary refining-fractionation process under medium pressure (reaction pressure ≤ 10.0MPa); the transformer oil produced by adding antioxidants later has excellent carbon structure, antioxidant performance, solubility and low temperature performance. Among them, cycloalkyl and paraffin-based mixed oils are selected as raw materials. Since cycloalkyl transformer oil is rich in cycloalkanes and suitable aromatics, when the aromatic hydrocarbon content is low, cycloalkyl transformer oil has good sensitivity to antioxidants, thus having good antioxidant performance and solubility, and can also ensure good electrical performance; paraffin-based transformer oil has a high viscosity index, and under the conditions of viscosity and pour point similar to cycloalkyl transformer oil, its low temperature kinematic viscosity is small, which is more conducive to the cold start of transformer oil. Therefore, by processing cycloalkyl and paraffin-based mixed oils, the transformer oil obtained has excellent carbon structure, antioxidant performance, solubility and low temperature performance.

[0070] In the present invention, the "cycloalkyl and paraffin-based mixed oil" refers to a mixed distillate oil obtained by mixing cycloalkyl distillate oil and paraffin-based distillate oil in a certain mass ratio.

[0071] As an optional embodiment, in step (1), the cycloalkyl and paraffin-based mixed oil comprises, by mass percentage, 10-40% of paraffin-based distillate oil and 60-90% of cycloalkyl distillate oil.

[0072] As an optional embodiment, based on the total mass of the cycloalkyl and paraffin-based mixed oil as 100%, the content of paraffin-based distillate oil is 10-40%, for example, it can be 10%, 12%, 14%, 15%, 16%, 18%, 20%, 22%, 24%, 25%, 26%, 28%, 30%, 32%, 34%, 35%, 36%, 38%, 40% and the like.

[0073] As an optional embodiment, based on the total mass of the cycloalkyl and paraffin-based mixed oil as 100%, the content of the paraffin-based distillate oil is 60-90%, for example, it can be 60%, 62%, 64%, 65%, 66%, 68%, 70%, 72%, 74%, 75%, 76%, 78%, 80%, 82%, 84%, 85%, 86%, 88%, 90% and the like.

[0074] In the present invention, cycloalkyl distillate oil and paraffin-grade distillate oil need to be mixed in a certain ratio, because if the cycloalkyl distillate oil is too much, the low-temperature kinematic viscosity will be large, which is not conducive to the cold start of the transformer oil, while if the paraffin-based distillate oil is too much, the transformer oil will have poor sensitivity to antioxidants, which is not conducive to the antioxidant stability of the transformer oil. The cycloalkyl and paraffin-based mixed oil includes: paraffin-based distillate oil 10-40% and cycloalkyl distillate oil 60-90% mixed raw materials hydrogenated transformer oil carbon structure, antioxidant performance, solubility and low temperature performance are very excellent.

[0075] As an optional embodiment, the paraffin-based distillate oil includes paraffin-based regular second-line and / or paraffin-based minus first-line, for example, it can be paraffin-based regular second-line, paraffin-based minus first-line, a mixed oil of paraffin-based regular second-line and minus first-line, etc.

[0076] As an optional embodiment, the cycloalkyl distillate oil includes cycloalkyl normal second line and / or cycloalkyl minus first line, for example, it can be cycloalkyl normal second line, cycloalkyl minus first line, a mixed oil of cycloalkyl normal second line and cycloalkyl minus first line, etc., and cycloalkyl normal second line is more preferred.

[0077] As an optional embodiment, in step (1), the hydroprocessing is carried out under the action of a hydroprocessing catalyst, and the hydroprocessing catalyst is a non-precious metal catalyst.

[0078] As an optional embodiment, the hydroprocessing catalyst includes an active metal oxide and a metal oxide promoter.

[0079] As an optional embodiment, in the hydroprocessing catalyst, the active metal oxide comprises a Group VIII metal oxide, preferably molybdenum trioxide and / or tungsten trioxide, preferably tungsten trioxide.

[0080] As an optional embodiment, in the hydroprocessing catalyst, the metal oxide promoter includes a Group VIB metal oxide, preferably cobalt trioxide and / or nickel oxide, preferably nickel oxide.

[0081] As an optional embodiment, in step (1), the hydroprocessing catalyst is prepared by the following steps:

[0082] (a) using water as a solvent to prepare a slurry of silicon-phosphorus-containing alumina; wherein the silicon-phosphorus-containing alumina comprises, by mass percentage, 0.5-20% SiO2, 0.5-15% P2O5, and the balance Al2O3; and the silicon-phosphorus-containing alumina is obtained by roasting silicon-phosphorus-containing pseudo-boehmite; wherein the mass fraction of water in the slurry is 50-90%;

[0083] (b) adding a boron-containing compound, a Group VIII metal oxide and / or a Group VIB metal oxide to the slurry, and filtering to obtain a filter cake and a filtrate;

[0084] (c) The filtrate is mixed with SB powder and nitric acid to obtain a binder, and the binder and the filter cake are successively rolled, formed (standing at 20-25°C for 4 hours), dried (dried at 80-150°C for 4-8 hours) and calcined (calcined at a constant temperature of 200-230°C for 0.5-2 hours, then calcined at a constant temperature of 300-360°C for 0.5-2 hours, and finally calcined at a constant temperature of 450-500°C for 2-4 hours) to obtain the hydrorefining catalyst; wherein the amount of the SB powder added is 10-48% of the mass of the hydrorefining catalyst; and the amount of the nitric acid added is 0.5-5% of the mass of the silicon-phosphorus-containing alumina.

[0085] As an optional embodiment, in step (1), the hydroprocessing catalyst has an appearance of a cloverleaf structure.

[0086] As an optional embodiment, in step (1), the pore volume of the hydroprocessing catalyst is greater than 0.30 cm 3 ·g -1 , for example, it can be 0.305cm 3 ·g -1 、0.31cm 3 ·g -1 、0.32cm 3 ·g -1 、0.33cm 3 ·g -1 、0.34cm 3 ·g -1 、0.35cm 3 ·g -1 、0.36cm 3 ·g -1 、0.37cm 3 ·g -1 、0.38cm 3 ·g -1 、0.39cm 3 ·g -1 、0.40cm 3 ·g -1 wait.

[0087] As an optional embodiment, in step (1), the specific surface area of ​​the hydroprocessing catalyst is greater than 200 m 2 ·g -1 , for example, it can be 201m 2 ·g -1 、202m 2 ·g -1 、203m2 ·g -1 、204m 2 ·g -1 、205m 2 ·g -1 、206m 2 ·g -1 、208m 2 ·g -1 、210m 2 ·g -1 、212m 2 ·g -1 、214m 2 ·g -1 、216m 2 ·g -1 、218m 2 ·g -1 、220m 2 ·g -1 、222m 2 ·g -1 、224m 2 ·g -1 、225m 2 ·g -1 、226m 2 ·g -1 、228m 2 ·g -1 、230m 2 ·g -1 wait.

[0088] As an optional embodiment, in step (1), the bulk density of the hydroprocessing catalyst is 0.75 to 0.90 g·cm -3 , for example, it can be 0.75 g·cm -3 , 0.76 g·cm -3 , 0.78 g·cm -3 , 0.80g·cm -3 , 0.82g·cm -3 , 0.84 g·cm -3 , 0.85g·cm -3 , 0.86 g·cm -3 , 0.88 g·cm -3 , 0.90g·cm -3 wait.

[0089] As an optional embodiment, in step (1), the diameter of the hydroprocessing catalyst is 1.3 to 1.6 mm, for example, it can be 1.3 mm, 1.35 mm, 1.4 mm, 1.45 mm, 1.5 mm, 1.55 mm, 1.6 mm, etc.

[0090] As an optional embodiment, in step (1), the crushing strength of the hydroprocessing catalyst is greater than 10 N·mm -1 , for example, it can be 10.1N·mm -1 、11N·mm -1 、12N·mm -1 、13N·mm -1 、14N·mm -1 、15N·mm -1 、16N·mm -1 、17N·mm -1 、18N·mm -1 、19N·mm -1 , 20N·mm -1 wait.

[0091] As an optional embodiment, in step (1), the reaction pressure of the hydrotreatment is 8.0-10.0 MPa, for example, it can be 8.0 MPa, 8.2 MPa, 8.4 MPa, 8.5 MPa, 8.6 MPa, 8.8 MPa, 9.0 MPa, 9.2 MPa, 9.4 MPa, 9.5 MPa, 9.6 MPa, 9.8 MPa, 10.0 MPa, etc.

[0092] As an optional embodiment, in step (1), the reaction temperature of the hydrotreatment is 300-370°C, for example, it can be 300°C, 305°C, 310°C, 315°C, 320°C, 325°C, 330°C, 335°C, 340°C, 345°C, 350°C, 355°C, 360°C, 365°C, 370°C, etc.

[0093] As an optional embodiment, in step (1), the volume ratio of the cycloalkyl and paraffin-based mixed oil to hydrogen is 1:(600-1200), for example, it can be 1:600, 1:700, 1:800, 1:900, 1:1000, 1:1100, 1:1200, etc.

[0094] As an optional embodiment, in step (1), the volume space velocity of the hydroprocessing is 0.2 to 1.0 h -1 , for example, it can be 0.2h -1 、0.3h -1 、0.4h -1 , 0.5h -1 , 0.6h -1 、0.7h -1 、0.8h -1 、0.9h -1 , 1.0h -1 wait.

[0095] As an optional embodiment, in step (2), the hydrodegradation treatment is carried out under the action of a hydrodegradation catalyst, and the hydrodegradation catalyst is a non-precious metal catalyst.

[0096] As an optional embodiment, the hydrodegradation catalyst includes an active metal oxide and a catalyst carrier supporting the active metal oxide.

[0097] As an optional embodiment, the active metal oxide includes Group VIII metal oxide and / or Group VIB metal oxide, preferably nickel oxide and / or tungsten trioxide.

[0098] As an optional embodiment, the catalyst carrier includes a catalyst carrier support having through holes on its surface and a molecular sieve membrane located on the pore surface of the support; wherein the catalyst carrier support having through holes on its surface includes aluminum oxide and metal oxide additives, and the aluminum oxide and metal oxide additives form a spinel structure.

[0099] In the present invention, the hydrodegradation catalyst is preferably used to reduce the pour point of the hydrogenated oil by selectively removing macromolecular normal alkanes with high freezing points.

[0100] As an optional embodiment, the metal oxide additive includes nickel oxide and / or copper oxide.

[0101] As an optional embodiment, in step (2), the hydrodecondensation catalyst is prepared by the following steps:

[0102] (a) preparing a molecular sieve mother liquid and impregnating the catalyst carrier support, crystallizing the impregnated material, washing, drying and calcining to obtain a catalyst carrier;

[0103] The preparation of the catalyst carrier support comprises the following steps: mixing pseudo-boehmite, a peptizing agent, an extrusion aid, a pore-enlarging agent, a metal oxide additive precursor and water to form a strip, and then granulating, drying and calcining to obtain the catalyst carrier support; wherein the mass ratio of the pseudo-boehmite to the metal oxide additive precursor is 1:(0.02-0.06); the metal oxide additive precursor is selected from one or both of nickel nitrate and copper nitrate;

[0104] The drying temperature is 120-150° C. and the time is 6-10 hours; the calcination temperature is 800-1000° C. and the time is 2-6 hours.

[0105] (b) preparing a salt solution of an active metal and impregnating the catalyst support with the solution, and obtaining the hydrodegassing catalyst after drying and calcining;

[0106] The active metal salt solution is a Group VIII and / or Group VIB metal salt solution, preferably a nickel nitrate solution and / or a nickel nitrate-ammonium metatungstate solution, and the NiO concentration of the solution is 0.0126-0.095 g / mL; the drying temperature is 120-150° C., and the time is 6-10 h; the calcination temperature is 400-550° C., and the time is 2-6 h.

[0107] As an optional embodiment, in step (2), the hydrodecondensation catalyst has an appearance of a cloverleaf structure.

[0108] As an optional embodiment, in step (2), the pore volume of the hydrodecondensation catalyst is greater than 0.18 cm 3 ·g -1 , for example, it can be 0.181 cm 3 ·g -1 、0.182cm 3 ·g -1 、0.184cm 3 ·g -1 、0.185cm 3 ·g -1 、0.186cm 3 ·g -1 、0.188cm 3 ·g -1 、0.190cm 3 ·g -1 、0.195cm 3 ·g -1 , 0.20cm 3 ·g -1 、0.25cm 3 ·g -1 、0.30cm 3 ·g -1 、0.35cm 3 ·g -1 、0.40cm 3 ·g -1 、0.45cm 3 ·g -1 wait.

[0109] As an optional embodiment, in step (2), the specific surface area of ​​the hydrodecondensation catalyst is greater than 180 m 2 ·g -1 , for example, it can be 181m 2 ·g -1 、185m 2 ·g -1 、190m 2 ·g -1 、195m 2 ·g-1 、200m 2 ·g -1 、205m 2 ·g -1 、210m 2 ·g -1 、215m 2 ·g -1 、220m 2 ·g -1 、225m 2 ·g -1 、230m 2 ·g -1 、235m 2 ·g -1 、240m 2 ·g -1 、245m 2 ·g -1 、250m 2 ·g -1 wait.

[0110] As an optional embodiment, in step (2), the bulk density of the hydrodecondensation catalyst is 0.75 to 0.80 g·cm -3 , for example, it can be 0.75 g·cm -3 , 0.76 g·cm -3 , 0.78 g·cm -3 , 0.80g·cm -3 wait.

[0111] As an optional embodiment, in step (2), the diameter of the hydrodecondensation catalyst is 1.3 to 1.6 mm, for example, it can be 1.3 mm, 1.35 mm, 1.4 mm, 1.45 mm, 1.5 mm, 1.55 mm, 1.6 mm, etc.

[0112] As an optional embodiment, in step (2), the crushing strength of the hydrodecondensation catalyst is greater than 10 N·mm -1 , for example, it can be 10.1N·mm -1 、11N·mm -1 、12N·mm -1 、13N·mm -1 、14N·mm -1 、15N·mm -1 、16N·mm -1 、17N·mm -1 、18N·mm -1 、19N·mm -1 , 20N·mm -1 wait.

[0113] As an optional embodiment, in step (2), the reaction pressure of the hydrodecondensation treatment is 8.0-10.0 MPa, for example, it can be 8.0 MPa, 8.2 MPa, 8.4 MPa, 8.5 MPa, 8.6 MPa, 8.8 MPa, 9.0 MPa, 9.2 MPa, 9.4 MPa, 9.5 MPa, 9.6 MPa, 9.8 MPa, 10.0 MPa, etc.

[0114] As an optional embodiment, in step (2), the reaction temperature of the hydrodecondensation treatment is 280-340°C, for example, it can be 280°C, 285°C, 290°C, 295°C, 300°C, 305°C, 310°C, 315°C, 320°C, 325°C, 330°C, 335°C, 340°C, etc.

[0115] As an optional embodiment, in step (2), the volume ratio of the hydrotreated oil to hydrogen is 1:(600-1200), for example, it can be 1:600, 1:700, 1:800, 1:900, 1:1000, 1:1100, 1:1200, etc.

[0116] As an optional embodiment, in step (2), the volume space velocity of the hydrodecondensation treatment is 0.8 to 3.0 h -1 , for example, it can be 0.8h -1 , 1.0h -1 , 1.2h -1 , 1.4h -1 , 1.6h -1 , 1.8h -1 , 2.0h -1 , 2.2h -1 , 2.4h -1 , 2.6h -1 , 2.8h -1 , 3.0h -1 wait.

[0117] As an optional embodiment, in step (3), the refining treatment is carried out under the action of a supplementary refining catalyst; wherein the refining catalyst is a non-precious metal catalyst.

[0118] As an optional embodiment, the supplemental finishing catalyst comprises an active metal oxide.

[0119] As an optional embodiment, the active metal oxide includes Group VIII metal oxide and / or Group VIB metal oxide.

[0120] As an optional embodiment, the active metal oxide includes nickel oxide and / or tungsten trioxide.

[0121] As an optional embodiment, in step (3), the supplementary refined catalyst is prepared by the following steps:

[0122] (a) mixing pseudo-boehmite, a peptizing agent, an extrusion aid and water, rolling and extruding into strips, and then drying and calcining to prepare the catalyst carrier;

[0123] Wherein, the peptizing agent is any one of nitric acid, acetic acid, and citric acid, or a combination of at least two of them; the extrusion aid is any one of sesbania powder, starch, and methyl cellulose, or a combination of at least two of them; the ratio of the pseudo-boehmite, the peptizing agent, the extrusion aid, and water is 1:(0.01-0.06):(0.01-0.04):(1.0-1.5); the drying temperature is 120-150°C, and the drying time is 6-10 hours; the roasting temperature is 550-800°C, and the roasting time is 2-6 hours.

[0124] (b) preparing an auxiliary agent solution and impregnating and drying the catalyst support to obtain support A;

[0125] The auxiliary agent solution is any one of calcium nitrate, strontium nitrate and barium nitrate solutions or a combination of at least two thereof; in the auxiliary agent solution, the concentration of the auxiliary agent is 0.015 to 0.035 g / mL, calculated as metal oxide; in the carrier A, the mass content of the auxiliary agent is 1 to 3%, calculated as metal oxide; the drying temperature is 120 to 150° C., and the drying time is 6 to 10 hours.

[0126] (c) preparing an acidic Mo-Ni-P solution and an acidic W-Ni solution required for the catalyst composition;

[0127] Wherein, in the Mo-Ni-P solution, the mass ratios of MoO3, NiO and P in the lubricating oil hydrorefining catalyst are 20-25%, 3.0-5.0% and 2-2.5% respectively; the Mo-Ni-P solution contains MoO3 0.313-0.476 g / mL, NiO 0.0471-0.095 g / mL, and P 0.0314-0.0476 g / mL;

[0128] Among them, in the W-Ni solution, the mass ratios of WO3 and NiO in the lubricating oil hydrorefining catalyst are 28-32% and 4.0-6.0% respectively; the W-Ni solution contains WO3 0.484-0.607 g / mL and NiO 0.069-0.114 g / mL.

[0129] (d) adding the oil phase, the surfactant and the co-surfactant to the Mo-Ni-P solution or the W-Ni solution, stirring and mixing uniformly to obtain a water-in-oil microemulsion;

[0130] The oil phase is selected from one or a mixture of C4-C10 cycloalkanes, straight-chain alkanes, and branched alkanes; the surfactant is a nonionic surfactant; the co-surfactant is a C4-C6 alcohol; the weight ratio of the surfactant, the co-surfactant and the oil phase is 1:(0.5-5):(1-6); the volume ratio of the surfactant to the Mo-Ni-P solution or the W-Ni solution is 1:(4-8).

[0131] (e) impregnating the carrier A with the microemulsion, drying and calcining to obtain a catalyst semi-finished product;

[0132] Wherein, the impregnation is saturated impregnation; the drying temperature is 120-150° C., and the drying time is 6-10 hours; the calcination temperature is 400-550° C., and the calcination time is 2-6 hours.

[0133] (f) impregnating the catalyst semi-finished product with the prepared W-Ni solution or Mo-Ni-P solution, and obtaining the supplementary refined catalyst through drying and calcination;

[0134] Wherein, the impregnation is unsaturated impregnation; the drying temperature is 120-150° C., and the drying time is 6-10 hours; the calcination temperature is 400-550° C., and the calcination time is 2-6 hours.

[0135] As an optional embodiment, in step (3), the appearance of the supplementary refined catalyst is a cloverleaf structure.

[0136] As an optional embodiment, in step (3), the pore volume of the supplementary refined catalyst is greater than 0.35 cm 3 ·g -1 , for example, it can be 0.351cm 3 ·g -1 、0.355cm 3 ·g -1 、0.36cm 3 ·g -1 、0.37cm 3 ·g -1 、0.38cm 3 ·g -1 、0.39cm 3 ·g -1 、0.40cm 3 ·g -1 、0.41cm 3 ·g -1 、0.42cm 3 ·g -1 、0.43cm 3·g -1 、0.44cm 3 ·g -1 、0.45cm 3 ·g -1 、0.5cm 3 ·g -1 wait.

[0137] As an optional embodiment, in step (3), the specific surface area of ​​the supplementary refined catalyst is greater than 150 m 2 ·g -1 , for example, it can be 151m 2 ·g -1 、152m 2 ·g -1 、153m 2 ·g -1 、154m 2 ·g -1 、155m 2 ·g -1 、156m 2 ·g -1 、158m 2 ·g -1 、160m 2 ·g -1 、162m 2 ·g -1 、164m 2 ·g -1 、166m 2 ·g -1 、168m 2 ·g -1 、170m 2 ·g -1 、172m 2 ·g -1 、174m 2 ·g -1 、175m 2 ·g -1 、176m 2 ·g -1 、178m 2 ·g -1 、180m 2 ·g -1 wait.

[0138] As an optional embodiment, in step (3), the bulk density of the supplementary refined catalyst is 0.82 to 0.88 g·cm -3 , for example, it can be 0.82 g·cm -3 , 0.83 g·cm -3 , 0.84 g·cm -3, 0.85g·cm -3 , 0.86 g·cm -3 , 0.87 g·cm -3 , 0.88 g·cm -3 ,wait.

[0139] As an optional embodiment, in step (3), the diameter of the supplementary refined catalyst is 1.0 to 1.4 mm, for example, it can be 1.0 mm, 1.05 mm, 1.1 mm, 1.15 mm, 1.2 mm, 1.25 mm, 1.3 mm, 1.35 mm, 1.4 mm, etc.

[0140] As an optional embodiment, in step (3), the reaction pressure of the refining treatment is 8.0-10.0 MPa, for example, it can be 8.0 MPa, 8.2 MPa, 8.4 MPa, 8.5 MPa, 8.6 MPa, 8.8 MPa, 9.0 MPa, 9.2 MPa, 9.4 MPa, 9.5 MPa, 9.6 MPa, 9.8 MPa, 10.0 MPa, etc.

[0141] As an optional embodiment, in step (3), the reaction temperature of the refining treatment is 290-360°C, for example, it can be 290°C, 295°C, 300°C, 305°C, 310°C, 315°C, 320°C, 325°C, 330°C, 335°C, 340°C, 345°C, 350°C, 355°C, 360°C, etc.

[0142] As an optional embodiment, in step (3), the volume ratio of the hydrodegradation product oil to hydrogen is 1:(600-1200), for example, it can be 1:600, 1:700, 1:800, 1:900, 1:1000, 1:1100, 1:1200, etc.

[0143] As an optional embodiment, in step (3), the volume space velocity of the refining treatment is 0.3 to 2.0 h -1 , for example, it can be 0.3h -1 、0.4h -1 , 0.5h -1 , 0.6h -1 、0.8h -1 , 1.0h -1 , 1.2h -1 , 1.4h -1 , 1.6h -1 , 1.8h -1 , 2.0h -1 , 2.2h -1 , 2.4h -1 , 2.6h -1 , 2.8h-1 , 3.0h -1 wait.

[0144] As an optional embodiment, in step (4), the pressure of the gas-liquid separation is 6 to 10 MPa, for example, it can be 6 MPa, 6.5 MPa, 7 MPa, 7.5 MPa, 8 MPa, 8.5 MPa, 9 MPa, 9.5 MPa, 10 MPa, etc., and the temperature of the gas-liquid separation is 100 to 220°C, for example, it can be 100°C, 120°C, 140°C, 160°C, 180°C, 200°C, 220°C, etc.

[0145] As an optional embodiment, in step (4), the distillation separation pressure is 0.14-0.18 MPa, for example, it can be 133.322 Pa, 133.323 Pa, 133.324 Pa, 133.325 Pa, 133.326 Pa, 133.328 Pa, 133.33 Pa, 133.332 Pa, etc.

[0146] In a second aspect, the present invention provides a Class I transformer oil base oil, wherein the Class I transformer oil base oil is prepared by the method for producing low-aromatic transformer oil by medium-pressure hydrogenation as described in the first aspect.

[0147] As an optional implementation, the sulfur content in the Class I transformer oil base oil is less than 1.0 mg / kg.

[0148] As an optional implementation, the nitrogen content in the Class I transformer oil base oil is less than 1.0 mg / kg.

[0149] As an optional implementation, the CA value of the Class I transformer oil base oil is less than 2.5%.

[0150] As an optional embodiment, the pour point of the Class I transformer oil base oil is <-57°C.

[0151] As an optional embodiment, the kinematic viscosity of the Class I transformer oil base oil at 40°C is less than 12.0 mm 2 / s.

[0152] As an optional embodiment, the kinematic viscosity of the Class I transformer oil base oil at -40°C is less than 2500 mm 2 / s.

[0153] As an optional implementation, the closed cup flash point of the Class I transformer oil base oil is greater than 140°C.

[0154] As an optional implementation, the yield of the Class I transformer oil base oil is >89.0%.

[0155] In a third aspect, the present invention provides a Class I transformer oil, wherein the Class I transformer oil comprises an antioxidant and the Class I transformer oil base oil as described in the second aspect.

[0156] As an optional implementation, the added amount of the antioxidant accounts for 0.05-0.5% of the total mass of the Class I transformer oil, preferably 0.15-0.25%.

[0157] As an optional embodiment, the antioxidant is selected from any one of 2,6-di-tert-butyl-p-cresol, benzothiadiazole antioxidants, phenolic antioxidants or phenolphthalein antioxidants, or a combination of at least two thereof, preferably 2,6-di-tert-butyl-p-cresol.

[0158] As an optional implementation, the aniline point of the Class I transformer oil is 72-78°C.

[0159] As an optional implementation, in the oxidation stability test at 120° C. and 500 h: the total acid value of the Class I transformer oil is less than 0.22 mgKOH / g, the sludge content is less than 0.0038%, and the dielectric loss factor at 90° C. is less than 0.17.

[0160] Preparation Example 1

[0161] This preparation example provides a hydroprocessing catalyst, which is prepared by the following steps:

[0162] (a) adding 100 g of calcined silicon-phosphorus-containing alumina powder (the mass fraction of SiO2 is 3.3%, the mass fraction of P2O5 is 2.0%, and the balance is Al2O3) to 300 mL of water (the mass fraction of water in the obtained slurry is 75%), stirring for 5 min, and obtaining a slurry of silicon-phosphorus-containing alumina;

[0163] (b) adding 18.6 g of boric acid (based on the mass of B2O2, the amount of boric acid added is 4.6% of the mass of the prepared hydrorefining catalyst), 73 g of ammonium metatungstate (based on the mass of WO3, the amount of ammonium metatungstate added is 28.3% of the mass of the prepared hydrorefining catalyst) and 37 g of nickel nitrate (based on the mass of NiO, the amount of nickel nitrate added is 4.1% of the mass of the prepared hydrorefining catalyst) to the slurry containing silicon-phosphorus-alumina, stirring for 1 h, standing for 2 h and then filtering to obtain a wet filter cake and a filtrate;

[0164] (c) The filtrate is mixed with 55 g of SB powder (the amount added is 19% of the mass of the prepared hydrotreating catalyst) and 4 mL of concentrated nitric acid (3.6% of the mass of the silicon- and phosphorus-containing alumina powder) to prepare a binder for use; the wet filter cake is dried at 120° C. for 8 h, crushed into powder, and mixed with 4 g of sesbania powder (the amount added is 4% of the mass of the silicon- and phosphorus-containing alumina powder) and the above-mentioned binder, and then formed into strips after rolling and extrusion. The strips are then cured at room temperature for 4 h, dried at 120° C. for 4 h, and then calcined at 230° C. for 1 h, 350° C. for 1 h, and finally 480° C. for 4 h to obtain the hydrotreating catalyst.

[0165] Preparation Example 2

[0166] This preparation example provides a hydrodegassing catalyst, which is prepared by the following steps:

[0167] (a) Weigh the pore volume of 1.095 mL / g and the specific surface area of ​​328 m2 produced by the aluminum sulfate method. 2 / g, 500g of pseudo-boehmite with a dry basis of 71%, 18.4g of nitric acid with a concentration of 65%, 10g of sesbania powder, 71g of carbon black, 60g of nickel nitrate additive and 754g of deionized water were added into a roller and rolled and mixed, extruded into cylindrical strips with an outer diameter of 6mm and an inner hollow diameter of 2.5mm, and dried under constant humidity and constant temperature conditions to a solid content of 65%; a punching device was used to punch evenly arranged circular through holes with a diameter of 1.5mm on the surface of the cylindrical strip, and particles with a length of 3-10mm were made, dried at 130°C for 8h, and then calcined at 900°C for 3h, A carrier support is obtained; 7.52 g of aluminum sulfate, 320 g of silica sol containing 30% silicon oxide, 2.15 g of sodium hydroxide, 1.81 g of triethylamine and 80 g of water are weighed respectively to prepare a ZSM-5 molecular sieve mother liquor; the prepared molecular sieve mother liquor is used to impregnate the above-mentioned carrier support, and the impregnated materials are placed on the upper part of the gas phase reactor, and deionized water is added to the bottom of the gas phase reactor. The reaction is carried out at 180°C for 36 hours. After the reaction is completed, the catalyst carrier containing the ZSM-5 molecular sieve membrane is obtained by washing with deionized water until it is neutral, drying at 130°C for 8 hours, and then calcining at 550°C for 3 hours.

[0168] (b) 30.3 g of nickel nitrate was weighed to prepare a solution containing 0.019 g / mL of nickel oxide and the solution was impregnated into the catalyst support. After the impregnation, the material was dried at 120° C. for 8 h and calcined at 450° C. for 3 h to obtain the hydrodecondensation catalyst.

[0169] Preparation Example 3

[0170] This preparation example provides a supplementary refined catalyst, which is prepared by the following steps:

[0171] (a) Weigh the pore volume of aluminum sulfate produced by 1.095 mL / g and the specific surface area of ​​328 m 2 500 g of pseudo-boehmite (71% on dry basis), 18.4 g of nitric acid (65%), 10 g of sesbania powder and 694 g of deionized water were added into a roller and rolled and mixed, and after extrusion, the mixture was dried at 120° C. for 10 h, and then calcined at 750° C. for 3 h to obtain a clover-shaped catalyst carrier for standby use;

[0172] (b) preparing 90 mL of a calcium nitrate solution containing 0.02 g / mL of calcium oxide, weighing 100 g of the above carrier and impregnating it, and then drying at 140° C. for 8 h to obtain a carrier A for standby use;

[0173] (c) The catalyst composition is MoO322%, NiO3.5%, P2.0%, and a Mo-Ni-P solution is prepared based on the water absorption of the calcium-containing carrier, wherein the MoO3 concentration is 0.344 g / mL, the NiO concentration is 0.055 g / mL, and the P concentration is 0.031 g / mL; the volume ratio of the prepared catalyst Mo-Ni catalyst in the catalyst is 40%;

[0174] The catalyst composition is WO3 32%, NiO 5.5%, and a W-Ni solution is prepared based on the water absorption rate of the carrier, wherein the WO3 concentration is 0.582 g / mL and the NiO concentration is 0.1 g / mL; the volume ratio of the pre-prepared W-Ni catalyst in the catalyst is 40%.

[0175] (d) 52.8 mL of the Mo-Ni-P solution was weighed, and after starting stirring, 26.5 g of isooctane, 5.0 g of polyoxyethylene glycol octylphenyl ether, and 8.0 g of n-pentanol were added respectively, and after mixing evenly, stirring was continued for 50 min to obtain a water-in-oil microemulsion;

[0176] (e) Weighing 100 g of the calcium-containing carrier, impregnating the carrier with 88 mL of the water-in-oil microemulsion, drying at 120° C. for 8 h, and then calcining at 450° C. for 3 h to obtain a catalyst semi-finished product;

[0177] (f) 52.8 mL of the W-Ni solution was taken to impregnate the semi-finished catalyst, dried at 120° C. for 10 h, and then calcined at 500° C. for 3 h to obtain the supplementary refined catalyst.

[0178] Test Example 1

[0179] Catalyst property testing

[0180] Test sample: each supplementary refined catalyst provided in Preparation Examples 1 to 3;

[0181] The test results are shown in Table 1 below:

[0182] Table 1

[0183] project Hydroprocessing catalyst Hydrodecondensation catalyst Supplementary refining catalyst Appearance Shamrock Shamrock Shamrock <![CDATA[Pore volume / (cm 3 ·g -1 )]]> 0.4 0.758 0.387 <![CDATA[Specific surface area / (m 2 ·g -1 )]]> 220 186 180 <![CDATA[Bulk density / (g·cm -3 )]]> 0.89 0.73 0.91 Diameter / mm 3-8 3-8 3-8 <![CDATA[Crushing strength / (N·mm -1 )]]> 126 118 116 <![CDATA[Mass fraction of WO3 / %]]> 25.7 0 22.3 NiO mass fraction / % 3.6 2.0 4.6 <![CDATA[Mass fraction of MoO3 / %]]> 0 0 7.5

[0184] The present invention is further described below by way of examples. Unless otherwise specified, the materials in the examples are prepared according to existing methods or purchased directly from the market.

[0185] The analysis parameters of the raw material oil in the following examples are shown in Table 2 below:

[0186] Table 2

[0187]

[0188] Wherein, mixed oil 1# is a cycloalkyl and paraffin-based mixed oil, which is composed of 20% paraffin-based conventional second-line and 80% cycloalkyl-based conventional second-line in terms of mass percentage.

[0189] Among them, the mixed oil 2# is a cycloalkyl and paraffin-based mixed oil, which is composed of 30% paraffin-based conventional second-line and 70% cycloalkyl-based conventional second-line in terms of mass percentage.

[0190] Example 1

[0191] This embodiment provides a method for preparing low-aromatic transformer oil by medium-pressure hydrogenation, the method comprising the following steps:

[0192] The mixed oil 1# produced by a refinery in Table 2 is used as the raw material (in terms of mass percentage, the paraffin-based conventional second-line accounts for 20%, and the cycloalkyl-based conventional second-line accounts for 80%). The raw material is mixed with hydrogen and then passes through the hydrotreating catalyst of the first hydrogenation reactor and the hydrodecondensation and refining catalyst of the second hydrogenation reactor in sequence. The feed volume space velocity is 1.0h -1 The volume ratio of hydrogen to oil is 600:1, and the system hydrogen partial pressure is 9.5 MPa. Among them, the filling volume ratio of the three catalysts of hydrotreatment, hydrodecondensation and supplementary refining is 3:1:2. The average reaction temperatures of the three catalysts are 345°C, 340°C and 340°C, respectively. After gas-liquid separation (10 MPa, 130°C) and distillation separation (133.3 Pa) of the product, the product, namely, type I transformer oil base oil, is extracted from the side line of the vacuum tower at >260°C. 2,6-di-tert-butyl-p-cresol is added to the obtained transformer oil base oil in an amount of 0.2±0.05% to obtain type I transformer oil.

[0193] Example 2

[0194] This embodiment provides a method for preparing low-aromatic transformer oil by medium-pressure hydrogenation, the method comprising the following steps:

[0195] The mixed oil 2# produced by a refinery in Table 2 is used as the raw material (in terms of mass percentage, the paraffin-based conventional second-line accounts for 30% and the cycloalkyl-based conventional second-line accounts for 70%). The raw material is mixed with hydrogen and then passes through the hydrotreating catalyst of the first hydrogenation reactor and the hydrodecondensation and refining catalyst of the second hydrogenation reactor in sequence. The feed volume space velocity is 1.0h -1 The volume ratio of hydrogen to oil is 600:1, and the system hydrogen partial pressure is 9.5 MPa. Among them, the filling volume ratio of the three catalysts of hydrotreatment, hydrodecondensation and supplementary refining is 3:1:2. The average reaction temperatures of the three catalysts are 345°C, 340°C and 345°C, respectively. After gas-liquid separation (10 MPa, 150°C) and distillation separation (133.3 Pa) of the product, the product, namely, type I transformer oil base oil, is extracted from the side line of the vacuum tower at >260°C. 2,6-di-tert-butyl-p-cresol is added to the obtained transformer oil base oil in an amount of 0.2%±0.05% to obtain type I transformer oil.

[0196] Example 3

[0197] This embodiment provides a method for preparing low aromatic transformer oil by medium pressure hydrogenation. The difference from the embodiment 1 is that in the hydrogenation treatment, hydrodecondensation treatment and refining treatment, the feed volume space velocity is 0.8h -1 , hydrogen-oil volume ratio is 800:1, system hydrogen partial pressure is 8.0 MPa, and other steps are exactly the same as those in Example 1.

[0198] Example 4

[0199] This embodiment provides a method for preparing low aromatic transformer oil by medium pressure hydrogenation. The difference from the embodiment 1 is that in the hydrogenation treatment, hydrodecondensation treatment and refining treatment, the volumetric space velocity of the hydrogenation treatment is 1.0 h -1 The volumetric space velocity of the hydrodecondensation treatment is 1.5h -1 The volumetric space velocity of the refining treatment is 2.0h -1 , the hydrogen-to-oil volume ratio is 1000:1, the system hydrogen partial pressure is 10.0 MPa, and the other steps are exactly the same as in Example 1.

[0200] Example 5

[0201] This embodiment provides a method for preparing low-aromatic transformer oil by medium-pressure hydrogenation. The only difference from Embodiment 1 is that mixed oil 3# produced by a refinery is used as a raw material (in terms of mass percentage, the paraffin-based conventional second-line accounts for 10%, and the cycloalkyl conventional second-line accounts for 90%), and the other steps are exactly the same as those in Embodiment 1.

[0202] Example 6

[0203] This embodiment provides a method for preparing low-aromatic transformer oil by medium-pressure hydrogenation. The only difference from Embodiment 1 is that mixed oil 3# produced by a refinery is used as a raw material (in terms of mass percentage, the paraffin-based conventional second-line accounts for 40%, and the cycloalkyl conventional second-line accounts for 60%), and the other steps are exactly the same as those in Embodiment 1.

[0204] Example 7

[0205] This embodiment provides a method for preparing low-aromatic transformer oil by medium-pressure hydrogenation, which is different from Embodiment 1 only in that the paraffin-based normal two-line is replaced by the paraffin-based minus one-line, and the cycloalkyl normal two-line is replaced by the cycloalkyl minus one-line, and the other steps are exactly the same as those in Embodiment 1.

[0206] Example 8

[0207] This embodiment provides a method for preparing low-aromatic transformer oil by medium-pressure hydrogenation. The only difference from Embodiment 1 is that the filling volume ratio of the three catalysts of hydrotreatment, hydrodecondensation and supplementary refining is 1:2:3, and the other steps are exactly the same as those of Embodiment 1.

[0208] Example 9

[0209] This embodiment provides a method for preparing low-aromatic transformer oil by medium-pressure hydrogenation. The only difference from Embodiment 1 is that the filling volume ratio of the three catalysts of hydrotreatment, hydrodecondensation and supplementary refining is 3:0.5:2.5, and the other steps are exactly the same as those of Embodiment 1.

[0210] Example 10

[0211] This embodiment provides a method for preparing low-aromatic transformer oil by medium-pressure hydrogenation. The only difference from Embodiment 1 is that the average reaction temperatures of the three catalysts are 300° C., 280° C. and 290° C., respectively, and the other steps are completely consistent with Embodiment 1.

[0212] Embodiment 11

[0213] This embodiment provides a method for preparing low-aromatic transformer oil by medium-pressure hydrogenation. The only difference from Embodiment 1 is that the average reaction temperatures of the three catalysts are 370° C., 340° C. and 360° C., respectively, and the other steps are completely consistent with Embodiment 1.

[0214] Comparative Example 1

[0215] This comparative example provides a method for preparing low-aromatic transformer oil by medium-pressure hydrogenation, the method comprising the following steps:

[0216] The raw material is the second-line distillate oil produced by processing cycloalkane crude oil in the atmospheric and vacuum unit of a refinery in Table 2. After the raw material is mixed with hydrogen, it passes through the hydroprocessing catalyst of Preparation Example 1 in the first hydrogenation reactor, the hydrodecondensation of the second hydrogenation reactor of Preparation Example 2, and the supplementary refining catalyst of Preparation Example 3 in sequence, with a feed volume space velocity of 1.0 h -1 The volume ratio of hydrogen to oil is 600:1, and the system hydrogen partial pressure is 9.5 MPa. Among them, the filling volume ratio of the three catalysts of hydrotreatment, hydrodecondensation and supplementary refining is 3:1:2. The average reaction temperatures of the three catalysts are 345°C, 340°C and 340°C, respectively. After gas-liquid separation (10 MPa, 130°C) and distillation separation (133.3 Pa) of the product, the product, namely, transformer oil base oil, is extracted from the side line of the vacuum tower at >260°C. 2,6-di-tert-butyl-p-cresol is added to the obtained transformer oil base oil in an amount of 0.2±0.05% to obtain transformer oil.

[0217] Comparative Example 2

[0218] This comparative example provides a method for preparing low-aromatic transformer oil by medium-pressure hydrogenation, the method comprising the following steps:

[0219] The raw material is the second-line distillate oil produced by processing paraffin-based crude oil in the atmospheric and vacuum unit of a refinery in Table 2. After the raw material is mixed with hydrogen, it passes through the hydroprocessing catalyst of Preparation Example 1 in the first hydrogenation reactor, the hydrodecondensation of the second hydrogenation reactor of Preparation Example 2, and the supplementary refining catalyst of Preparation Example 3 in sequence, with a feed volume space velocity of 1.0 h -1 , the volume ratio of hydrogen to oil is 600:1, the system hydrogen partial pressure is 9.5MPa, wherein, the filling volume ratio of the three catalysts of hydrotreating, hydrodecondensation and supplementary refining is 3:1:2, the average reaction temperatures of the three catalysts are 340°C, 340°C and 355°C, respectively, after gas-liquid separation (10MPa, 150°C) and distillation separation (133.3Pa) of the product, the product, namely, transformer oil base oil, is extracted from the side line of the vacuum tower at >260°C, 2,6-di-tert-butyl-p-cresol is added to the obtained transformer oil base oil, and the addition amount is 0.2%±0.05% to obtain transformer oil.

[0220] Comparative Example 3

[0221] This comparative example provides a method for preparing low-aromatic transformer oil by medium-pressure hydrogenation. The difference from comparative example 1 is that the first-line distillate oil produced by processing cycloalkane crude oil in a refinery atmospheric and vacuum unit is used as raw material, and the other steps are completely consistent with comparative example 1.

[0222] Comparative Example 4

[0223] This comparative example provides a method for preparing low-aromatic transformer oil by medium-pressure hydrogenation. The difference from comparative example 2 is that the first-line distillate oil produced by processing paraffin-based crude oil in a refinery's atmospheric and vacuum distillation unit is used as raw material, and the other steps are completely consistent with comparative example 2.

[0224] Test Example 2

[0225] Transformer Oil Product Testing

[0226] Test samples: Type I transformer oil base oil and Type I transformer oil provided in Examples 1 to 11, and transformer oil base oil and transformer oil provided in Comparative Examples 1 to 4.

[0227] The test results of transformer oil base oil are shown in Table 3:

[0228] Table 3

[0229]

[0230]

[0231]

[0232] The test results of transformer oil are shown in Table 4:

[0233] Table 4

[0234]

[0235]

[0236] As shown in Table 3 above, the sulfur content of the Class I transformer oil base oil is less than 1.0 mg / kg; the nitrogen content is less than 1.0 mg / kg; the CA value is less than 2.5%; the pour point is less than -57°C; the kinematic viscosity at 40°C is less than 12.0 mm2 / s; and the kinematic viscosity at -40°C is less than 2500 mm 2 / s; closed cup flash point>140℃; yield>89.0%. As shown in Table 4 above, the aniline point of the Class I transformer oil is 72~78℃; in the oxidation stability at 120℃ and 500h: the total acid value of the Class I transformer oil is<0.22 mgKOH / g, the sludge content is<0.0038%, and the dielectric loss factor at 90℃ is<0.17.

[0237] Test Example 3

[0238] Transformer oil product stability test

[0239] Test sample: Type I transformer oil provided in Example 1.

[0240] Test method: The experiment was carried out with the same raw materials, process flow and operating conditions as in Example 1. The device was operated continuously for 120 days, and the transformer oil was sampled and analyzed for aromatic content and pour point every 48 hours to obtain periodic data.

[0241] The test results are as follows Figure 1 Shown by: Figure 1 It can be seen that the transformer oil base oil obtained by this technology has a pour point of -57°C and an aromatic content between 9 and 10%. It has the advantages of low pour point, low aromatic content, and stable properties, and is a high-quality transformer oil base oil product.

[0242] Test Example 4

[0243] Catalyst stability test

[0244] Test sample: Type I transformer oil provided in Examples 1-2.

[0245] Test principle: The main factor restricting the long-term operation of industrial equipment is the rapid growth of the pressure drop of the equipment. In addition to the well-known raw material factors, the growth rate of the pressure drop is directly related to the porosity of the catalyst itself, the permeability of the bed, and the distribution of logistics. The three hydrogenation catalysts have high porosity and good permeability, which are conducive to the diffusion of reactants and products, reduce the pressure drop of the decondensation catalyst bed, and are conducive to the long-term operation of the equipment. In order to verify the stability of the catalyst of the present invention and facilitate the long-term operation of the equipment, the stability of the catalyst of the present invention was verified on a medium-sized hydrogenation test device with a process flow similar to that of an industrial device.

[0246] Test method: Experiments were conducted using Example 1 and Example 2. The device was operated continuously for 2600 h. The static pressure drop between the inlet a of the first hydrogenation reactor R1 and the outlet b of the second hydrogenation reactor was measured at the 300th and 2600th h. The periodic data were shown in Table 5 (reactor pressure drop):

[0247] Table 5

[0248]

[0249]

[0250] The test results are shown in Table 5: After the device has been running continuously for 2600 hours, the total pressure drop has increased by 0.03 MPa compared with 300 hours, which fully meets the index requirements of industrial devices. Therefore, the three hydrogenation catalysts using this technology are conducive to the diffusion of reactants and products, reduce the pressure drop of the catalyst bed, and are conducive to the long-term operation of the device.

[0251] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing low aromatic transformer oil by medium pressure hydrogenation, characterized in that: The method comprises the following steps: (1) mixing cycloalkyl and paraffinic mixed oil with hydrogen and performing hydrogenation treatment to obtain hydrogenation product oil; (2) mixing the hydrotreated product oil with hydrogen and performing a hydrodecondensation treatment to obtain a hydrodecondensation product oil; (3) mixing the hydrodecondensation product oil with hydrogen and performing a refining treatment to obtain a refined product oil; (4) separating the refined oil into gas and liquid, separating the separated liquid product by rectification, collecting the fraction with a temperature greater than 260° C., and obtaining transformer oil base oil.

2. The method for preparing low aromatic transformer oil by medium pressure hydrogenation according to claim 1, characterized in that: In step (1), the cycloalkyl and paraffinic mixed oil comprises, by weight percentage, 10-40% of paraffinic distillate oil and 60-90% of cycloalkyl distillate oil; Preferably, the paraffin-based distillate oil includes paraffin-based regular second-line and / or paraffin-based minus first-line; Preferably, the naphthenic distillate oil comprises naphthenic normal second line and / or naphthenic minus first line; Preferably, in step (1), the hydroprocessing is carried out under the action of a hydroprocessing catalyst, and the hydroprocessing catalyst is a non-precious metal catalyst; Preferably, the hydroprocessing catalyst comprises an active metal oxide and a metal oxide promoter; Preferably, the active metal oxide comprises a Group VIII metal oxide, preferably molybdenum trioxide and / or tungsten trioxide; Preferably, the metal oxide promoter comprises a Group VIB metal oxide, preferably cobalt trioxide and / or nickel oxide; Preferably, in step (1), the reaction pressure of the hydrotreatment is 8.0 to 10.0 MPa; Preferably, in step (1), the reaction temperature of the hydrotreatment is 300-370°C; Preferably, in step (1), the volume ratio of the cycloalkyl and paraffinic mixed oil to hydrogen is 1:(600-1200); Preferably, in step (1), the volume space velocity of the hydroprocessing is 0.2 to 1.0 h -1 .

3. The method for preparing low aromatic transformer oil by medium pressure hydrogenation according to claim 1, characterized in that: In step (2), the hydrodegassing treatment is carried out under the action of a hydrodegassing catalyst, and the hydrodegassing catalyst is a non-precious metal catalyst; Preferably, the hydrodegradation catalyst comprises an active metal oxide and a catalyst carrier carrying the active metal oxide; Preferably, the active metal oxide comprises Group VIII metal oxide and / or Group VIB metal oxide, preferably nickel oxide and / or tungsten trioxide; Preferably, the catalyst carrier comprises a catalyst carrier support having through holes on the surface and a molecular sieve membrane located on the pore surface of the support; wherein the catalyst carrier support having through holes on the surface comprises aluminum oxide and a metal oxide additive, and the aluminum oxide and the metal oxide additive form a spinel structure; Preferably, the metal oxide additive comprises nickel oxide and / or copper oxide; Preferably, in step (2), the reaction pressure of the hydrodecondensation treatment is 8.0 to 10.0 MPa; Preferably, in step (2), the reaction temperature of the hydrodecondensation treatment is 280-340°C; Preferably, in step (2), the volume ratio of the hydroprocessed oil to hydrogen is 1:(600-1200); Preferably, in step (2), the volume space velocity of the hydrodecondensation treatment is 0.8 to 3.0 h -1 .

4. The method for preparing low aromatic transformer oil by medium pressure hydrogenation according to claim 1, characterized in that: In step (3), the refining treatment is carried out under the action of a supplementary refining catalyst, and the supplementary refining catalyst is a non-precious metal catalyst; Preferably, the supplemental refining catalyst comprises an active metal oxide; Preferably, the active metal oxide comprises a Group VIII metal oxide and / or a Group VIB metal oxide; Preferably, the active metal oxide comprises nickel oxide and / or tungsten trioxide; Preferably, in step (3), the reaction pressure of the refining treatment is 8.0 to 10.0 MPa; Preferably, in step (3), the reaction temperature of the refining treatment is 290 to 360°C; Preferably, in step (3), the volume ratio of the hydrodecondensation product oil to hydrogen is 1:(600-1200); Preferably, in step (3), the volume space velocity of the refining treatment is 0.3 to 2.0 h -1 .

5. The method for preparing low aromatic transformer oil by medium pressure hydrogenation according to claim 1, characterized in that: In step (4), the pressure of the gas-liquid separation is 6-10 MPa, and the temperature of the gas-liquid separation is 100-220° C.; Preferably, in step (4), the pressure of the distillation separation is 0.14-0.18 MPa.

6. A Class I transformer oil base oil, characterized in that: The Class I transformer oil base oil is prepared by the method for preparing low-aromatic transformer oil by medium-pressure hydrogenation according to any one of claims 1 to 5.

7. Class I transformer oil base oil according to claim 6, characterized in that, The sulfur content of the Class I transformer oil base oil is less than 1.0 mg / kg; Preferably, the nitrogen content in the Class I transformer oil base oil is less than 1.0 mg / kg; Preferably, the CA value of the Class I transformer oil base oil is less than 2.5%; Preferably, the pour point of the Class I transformer oil base oil is less than -57°C; Preferably, the kinematic viscosity of the Class I transformer oil base oil at 40°C is less than 12.0 mm 2 / s; Preferably, the kinematic viscosity of the Class I transformer oil base oil at -40°C is less than 2500 mm 2 / s; Preferably, the closed cup flash point of the Class I transformer oil base oil is greater than 140°C; Preferably, the yield of the Class I transformer oil base oil is >89.0%.

8. A Class I transformer oil, characterized in that: The Class I transformer oil comprises an antioxidant and the Class I transformer oil base oil as claimed in claim 6 or 7.

9. The Class I transformer oil according to claim 8, characterized in that: The antioxidant is added in an amount of 0.05-0.5% of the total mass of the Class I transformer oil, preferably 0.15-0.25%; Preferably, the antioxidant is selected from any one of 2,6-di-tert-butyl-p-cresol, benzothiadiazole antioxidants, phenolic antioxidants or phenolphthalein antioxidants, or a combination of at least two thereof, preferably 2,6-di-tert-butyl-p-cresol.

10. The Class I transformer oil according to claim 9, characterized in that: The aniline point of the Class I transformer oil is 72-78°C; Preferably, in the oxidation stability test at 120° C. and 500 h: the total acid value of the Class I transformer oil is less than 0.22 mgKOH / g, the sludge content is less than 0.0038%, and the dielectric loss factor at 90° C. is less than 0.17.

Images