Method for preparing transformer oil base oil from naphthenic base distillate oil and application of transformer oil base oil

Abstract

The invention provides a method for preparing transformer oil base oil from naphthenic base distillate oil and application of the transformer oil base oil, and relates to the technical field of transformer oil. Specifically, the method comprises the following steps: sequentially carrying out hydrotreating, hydrodewaxing, finishing and fractionating treatment on light naphthenic base distillate oil, and taking fractions with the temperature higher than 260 DEG C, so as to obtain the I-type transformer oil base oil, wherein the reaction pressure is controlled to be 7.5 MPa, and the catalyst in any process is a non-noble metal catalyst. According to the method, the I-type transformer oil base oil is directly produced by a mild hydrogenation process under the medium-pressure condition, the cost defect of a high-pressure hydrogenation device in the aspects of equipment and operation is avoided, the product yield can reach 96% or above, high-quality transformer oil can be further produced after a proper amount of antioxidant is added, and the method is suitable for industrial production. Good application prospects and economic benefits are realized.

Description

Technical Field

[0001] The invention relates to the technical field of transformer oil, and in particular to a method for preparing transformer oil base oil by using cycloalkane distillate oil and application thereof. Background Art

[0002] Aromatic transformer oil is a fractionation product of petroleum, mainly composed of saturated hydrocarbons, monocyclic aromatic hydrocarbons, dicyclic aromatic hydrocarbons, polycyclic aromatic hydrocarbons and colloids, etc. It plays an important role in insulation, heat dissipation, cooling, arc extinguishing and other equipment in cables, capacitors, oil switches, transformers, oil-filled transformers and compensators. At present, aromatic transformer oil is usually obtained by multiple hydrogenation reactions of raw materials such as heavy distillate oil directly liquefied from coal. The hydrogenation reaction can saturate some aromatic hydrocarbons to form cycloalkanes, or cause some ring structures in polycyclic cycloalkanes to undergo ring-opening reactions, etc., thereby obtaining transformer oil with a lower content of condensed aromatic hydrocarbons.

[0003] CN106753555A discloses a method for preparing low-freezing-point transformer oil by high-pressure hydrogenation, comprising: adding cycloalkane oil and a hydrogenation catalyst after sulfurization passivation treatment to a reactor, introducing hydrogen, heating up for hydrocracking reaction, performing gas-liquid separation after the reaction is completed, adding a hydrodecondensation catalyst, introducing hydrogen, heating up for shape-selective cracking reaction, performing gas-liquid separation after the reaction is completed, and then adding activated clay for refining to obtain the low-freezing-point transformer oil. The method proposed in the patent has the advantages of simple process operation and mild conditions, and the prepared transformer oil not only has excellent low-temperature flow performance, but also has light color and good electrical properties. However, the method needs to perform gas-liquid separation and liquid-solid separation twice, which is complicated to operate and has high energy consumption, and also needs to be refined with clay, which will bring about the problem of waste clay processing.

[0004] CN106833740A discloses a method for preparing transformer oil base oil, comprising: (1) performing a hydrorefining treatment on a light cycloalkyl fraction oil under the action of a catalyst to obtain a hydrorefined product oil; (2) performing a hydroisomerization on the hydrorefined product oil to obtain a hydroisomerized product oil; (3) performing a hydrogenation supplementary refining on the hydroisomerized product oil to obtain a three-stage hydrogenated product oil, and then performing atmospheric and vacuum fractionation, and the fraction greater than 280°C is the transformer oil base oil. The process is a full hydrogen process under medium pressure conditions, and the obtained transformer oil base oil improves the oxidation stability of the transformer oil without adding a metal passivator, and retains some cycloalkyl characteristics, which can meet the requirements of the new transformer oil IEC60296-2012 standard; at the same time, the yield of the transformer oil base oil can be increased by more than 8% compared with the traditional process. However, the hydroisomerization catalyst in this method is a precious metal catalyst with a mixture of SAPO-11 and ZSM-22 molecular sieves as a carrier and Pt / Pd as an active metal, which is expensive, resulting in a high production cost of transformer oil base oil.

[0005] CN101386792A discloses a transformer oil base oil and its preparation method and application, comprising: 1) refining SZ36-1 ordinary second-line distillate oil with furfural to obtain refined oil, removing furfural to obtain de-aldehyde refined oil; 2) denitrogenating the de-aldehyde refined oil to remove nitrogen residue to obtain denitrogenated refined oil; 3) adding kaolin to the denitrogenated refined oil to perform kaolin refining to obtain transformer oil base oil. However, this method cannot produce transformer oil with a low pour point, and there are problems such as low transformer oil yield and difficulty in handling waste kaolin.

[0006] In view of this, the present invention is proposed. Summary of the invention

[0007] The first purpose of the present invention is to provide a method for preparing transformer oil base oil from cycloalkane distillate oil, which is mainly used to solve the problem that in the prior art, kaolin refining is required to carry out denitrification and decolorization in the process of preparing transformer oil from cycloalkane distillate oil, resulting in the introduction of waste kaolin treatment; and to solve the defects of high-pressure hydrogenation technology, such as complex process flow, large one-time investment scale, high pour point or low yield of the transformer oil produced.

[0008] A second object of the present invention is to provide a Class I transformer oil base oil.

[0009] A third object of the present invention is to provide a Class I transformer oil.

[0010] A fourth object of the present invention is to provide the Class I transformer oil base oil or the use of the Class I transformer oil in transformers.

[0011] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0012] A method for preparing transformer oil base oil from cycloalkane distillate oil comprises the following steps:

[0013] The light cycloalkane fraction oil is subjected to hydrogenation treatment, hydrodecondensation, additional refining and fractionation treatment in sequence, and the fraction with a temperature of more than 260° C. is taken to obtain a Class I transformer oil base oil;

[0014] Wherein, the reaction pressure of the method is 7.5MPa and the catalyst in the method is a non-precious metal catalyst.

[0015] A type I transformer oil base oil is prepared by adopting the method for preparing transformer oil base oil by using cycloalkane distillate oil.

[0016] A type I transformer oil comprises the type I transformer oil base oil.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] (1) The present invention can directly produce Class I transformer oil base oil by using cycloalkyl distillate oil as raw material and non-precious metal catalyst under the condition of reaction pressure of 7.5MPa through hydrogenation treatment-hydrodecondensation-supplementary refining-fractionation process. Further, the Class I transformer oil base oil prepared by the present invention meets the index requirements related to I-40# in GB2536-2011 after adding an appropriate amount of antioxidant, and has good quality and yield.

[0019] (2) The method for preparing transformer oil base oil from cycloalkane distillate provided by the present invention has a base oil yield of more than 96.0%, which has high yield and practicality. When processing cycloalkane distillate oil, it is preferred to use a specific catalyst, especially in the selection of catalysts in the hydrodecondensation process, the pores of the catalyst only allow straight-chain alkanes and nearly straight-chain isoalkanes in the feed oil to enter, and crack into small molecular hydrocarbons at their acidic centers; thus, it is difficult for cycloalkanes to enter the pores of the catalyst for cracking, and the ideal components of cycloalkanes are retained while cracking high pour point alkanes, and the overall process embodies the common advantages of mild hydrogenation process conditions and high base oil product yield.

[0020] (3) The present invention solves the problem that conventional fuel oil refineries have difficulty in producing transformer oil using existing hydrogenation equipment and process technology without modifying the diesel hydrogenation equipment. The present invention realizes the full hydrogenation process of transformer oil under medium-pressure conditions by grading high-activity catalysts with different functions, avoiding the increase in equipment investment and harsh operating pressure caused by the use of high-pressure hydrogenation equipment, and has the advantages of small investment scale of production equipment, cost reduction and efficiency improvement, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] 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.

[0022] Figure 1 Provided is a data graph of the periodic change of the aromatic content and pour point of the transformer oil base oil of Example 1 of the present invention. DETAILED DESCRIPTION

[0023] The technical scheme of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments, but those skilled in the art will appreciate that the following described embodiments are part of embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention. If specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer is not specified in the reagents or instruments used, they are all conventional products that can be purchased commercially. In addition, the terms "first", "second" and "third" are only used for descriptive purposes and cannot be interpreted as indicating or implying relative importance.

[0024] The first aspect of the present invention is to provide a method for preparing transformer oil base oil from cycloalkyl distillate oil, which mainly comprises the following steps: subjecting light cycloalkyl distillate oil to hydrogenation treatment, hydrodecondensation, additional refining and fractionation treatment in sequence, taking the fraction with a temperature of more than 260°C to obtain Class I transformer oil base oil; wherein the reaction pressure of the method is 7.5MPa and the catalyst in the method is a non-precious metal catalyst. It should be noted that the reaction pressure of the method refers to the pressure of 7.5MPa that the hydrogenation treatment, the hydrodecondensation and the additional refining all meet.

[0025] In the first aspect of the present invention, light naphthenic distillate oil is used as raw material under medium pressure (7.5MPa), non-precious metal catalyst is used, and the process of hydrotreatment-hydrodecondensation-supplementary refining-fractionation process can directly generate Class I transformer oil base oil, which has the advantages of simple process, low cost, high product yield, etc. In addition, the present invention has a wide range of adaptability to raw material oil, obtains high value-added transformer oil base oil products with low value-added raw materials under relatively low reaction pressure, reduces the dependence on hydrogenation reaction pressure, makes full use of high-quality naphthenic crude oil resources, and has relatively high overall economic benefits.

[0026] It is noteworthy that the present invention adopts a "shallow hydrogenation process", specifically, it is a process of hydrogenating under mild temperature or pressure conditions, using a catalyst to react the raw material with hydrogen to reduce or minimize the occurrence of hydrocracking reactions.

[0027] As a preferred embodiment, the light naphthenic distillate oil is obtained by distilling naphthenic crude oil under normal pressure, and its parameter properties are as follows: kinematic viscosity at 40°C is 8.0 mm 2 / s~10.0mm 2 / s,C A ≤18%; it can be understood that the light cycloalkane distillate oil is a type of cycloalkane distillate oil, which is mainly composed of light cycloalkanes, that is, cycloalkanes with a small number of carbon atoms, and has the characteristics of low molecular weight, low boiling point, etc.

[0028] As a preferred embodiment, the hydrotreatment, the hydrodecondensation and the supplementary refining of the present invention can be carried out in one reactor, or can be divided into two reactors, or can be carried out through three different reactors; it can be understood that the conventional operation of the prior art requires two independent reactors when carrying out the three hydrogenation steps, while the present invention can achieve efficient reaction in one reactor.

[0029] Further, it should be noted that the hydroprocessing of the present invention is a process of mixing oil products with hydrogen and performing a heat exchange reaction, optimizing the component structure of the oil products through the hydrogenation reaction of the oil products, increasing the content of alkanes, and thus reducing the content of isoalkanes and olefins; the hydrodecondensation of the present invention is a decondensation reaction carried out by a catalyst under hydrogenation conditions after the hydroprocessing to crack the normal alkanes in the oil products and reduce the freezing point of the oil products; the supplementary refining of the present invention is to further purify the oil products after the hydrodecondensation, and its operation method is consistent with the hydroprocessing. In addition, the fractionation treatment of the present invention can be understood as a conventional fractionation process, which is a process of separating the components in the oil products by boiling point.

[0030] As a preferred embodiment, the temperature of the hydrotreatment is 280°C to 380°C, including but not limited to any one of 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, 380 (°C) or a numerical range consisting of any two of them.

[0031] As a preferred embodiment, the catalyst for the hydrogenation treatment includes at least one of a molybdenum-nickel hydrogenation catalyst, a tungsten-nickel hydrogenation catalyst, a molybdenum-cobalt hydrogenation catalyst or a molybdenum-tungsten-nickel hydrogenation catalyst, wherein typical but non-limiting combinations include: a combination of a molybdenum-nickel hydrogenation catalyst and a tungsten-nickel hydrogenation catalyst, a combination of a molybdenum-cobalt hydrogenation catalyst and a molybdenum-tungsten-nickel hydrogenation catalyst, a combination of a molybdenum-nickel hydrogenation catalyst, a tungsten-nickel hydrogenation catalyst, a molybdenum-cobalt hydrogenation catalyst and a molybdenum-tungsten-nickel hydrogenation catalyst, and the like.

[0032] As a more preferred embodiment, the catalyst for the hydrogenation treatment adopts a tungsten-nickel hydrogenation catalyst because it has better hydrogenation dearomatization performance than a molybdenum-cobalt hydrogenation catalyst or a tungsten-nickel hydrogenation catalyst, while the hydrogenation dearomatization performance of the molybdenum-nickel hydrogenation catalyst and the molybdenum-tungsten-nickel hydrogenation catalyst is slightly worse.

[0033] As a preferred embodiment, the volume ratio of hydrogen to the light cycloalkane distillate oil in the hydrotreatment is (600-1500):1, and this volume ratio is dimensionless; optionally, any one of 600:1, 700:1, 800:1, 900:1, 1000:1, 1100:1, 1200:1, 1300:1, 1400:1, 1500:1 or a numerical range consisting of any two of them can be used.

[0034] As a preferred embodiment, the volume space velocity of the hydroprocessing is 0.2h -1 ~2.5h -1 , including but not limited to 0.2, 0.4, 0.5, 0.6, 0.8, 1.0, 1.2, 1.5, 1.8, 2.0, 2.2, 2.4, 2.5 (h -1 ) or any two of them.

[0035] As a preferred embodiment, the hydrodecondensation temperature is 300°C to 380°C, including but not limited to any one of 300, 310, 320, 330, 340, 350, 360, 370, 380 (°C) or a numerical range consisting of any two of them.

[0036] As a preferred embodiment, the catalyst for hydrodecondensation includes at least one of a nickel-type molecular sieve-containing catalyst, a molybdenum-nickel molecular sieve-containing catalyst, a tungsten-nickel molecular sieve-containing catalyst or a molybdenum-tungsten-nickel molecular sieve-containing catalyst, wherein typical but non-limiting combinations include: a combination of a nickel-type molecular sieve-containing catalyst and a molybdenum-nickel molecular sieve-containing catalyst, a combination of a tungsten-nickel molecular sieve-containing catalyst and a molybdenum-tungsten-nickel molecular sieve-containing catalyst, a combination of a nickel-type molecular sieve-containing catalyst, a molybdenum-nickel molecular sieve-containing catalyst, a tungsten-nickel molecular sieve-containing catalyst and a molybdenum-tungsten-nickel molecular sieve-containing catalyst, and the like.

[0037] As a more preferred embodiment, the catalyst for the hydrodecondensation is a nickel-type molecular sieve-containing catalyst because it has better selective cracking performance than a molybdenum-nickel molecular sieve-containing catalyst or a tungsten-nickel molecular sieve-containing catalyst, and the metal active center of nickel is better matched with the acid center of the molecular sieve.

[0038] As a preferred embodiment, the volume ratio of hydrogen to oil in the hydrodecondensation is (600-1500):1, which is dimensionless; optionally, any one of 600:1, 700:1, 800:1, 900:1, 1000:1, 1100:1, 1200:1, 1300:1, 1400:1, 1500:1 or a numerical range consisting of any two of them can be used.

[0039] As a preferred embodiment, the volume space velocity of the hydrocondensation is 0.2h -1 ~2.5h -1 , including but not limited to 0.2, 0.4, 0.5, 0.6, 0.8, 1.0, 1.2, 1.5, 1.8, 2.0, 2.2, 2.4, 2.5 (h -1 ) or any two of them.

[0040] As a preferred embodiment, the temperature of the supplementary refining is 300°C to 380°C, including but not limited to any one of 300, 310, 320, 330, 340, 350, 360, 370, 380 (°C) or a numerical range consisting of any two of them.

[0041] As a preferred embodiment, the supplementary refined catalyst includes at least one of a molybdenum-nickel hydrogenation catalyst, a tungsten-nickel hydrogenation catalyst, a molybdenum-cobalt hydrogenation catalyst or a molybdenum-tungsten-nickel hydrogenation catalyst, wherein typical but non-limiting combinations include: a combination of a molybdenum-nickel hydrogenation catalyst and a tungsten-nickel hydrogenation catalyst, a combination of a molybdenum-cobalt hydrogenation catalyst and a molybdenum-tungsten-nickel hydrogenation catalyst, a combination of a molybdenum-nickel hydrogenation catalyst, a tungsten-nickel hydrogenation catalyst, a molybdenum-cobalt hydrogenation catalyst and a molybdenum-tungsten-nickel hydrogenation catalyst, and the like.

[0042] As a more preferred embodiment, the supplementary refining catalyst uses one or both of a tungsten-nickel type hydrogenation catalyst or a molybdenum-tungsten-nickel type hydrogenation catalyst, because they have good deep dearomatization and decolorization properties, which help to obtain a purer product base oil.

[0043] As a preferred embodiment, the volume ratio of hydrogen to oil in the supplementary refining is (600-1500):1, which is dimensionless; optionally, any one of 600:1, 700:1, 800:1, 900:1, 1000:1, 1100:1, 1200:1, 1300:1, 1400:1, 1500:1 or a numerical range consisting of any two of them can be used.

[0044] As a preferred embodiment, the volume space velocity of the supplementary refining is 0.2h -1 ~2.5h -1 , including but not limited to 0.2, 0.4, 0.5, 0.6, 0.8, 1.0, 1.2, 1.5, 1.8, 2.0, 2.2, 2.4, 2.5 (h -1 ) or any two of them.

[0045] The second aspect of the present invention is to provide a Class I transformer oil base oil, which is prepared by the method for preparing transformer oil base oil using cycloalkane distillate oil as described in the first aspect.

[0046] As a preferred embodiment, the Class I transformer oil base oil of the present invention has the following properties: sulfur content <10.0 mg / kg, nitrogen content <3.0 mg / kg, C A Value <4.7%, pour point <-57℃, kinematic viscosity at 40℃ <12.0mm 2 / s, closed cup flash point>140°C. In addition, through repeated experiments, it is verified that the base oil yield obtained by the method described in the first aspect is>96.0%.

[0047] The third aspect of the present invention is to provide a Class I transformer oil, comprising the Class I transformer oil base oil as described in the second aspect.

[0048] The Class I transformer oil of the present invention comprises the Class I transformer oil base oil, an antioxidant, and other optional non-essential functional components. Those skilled in the art can adjust the components of the Class I transformer oil according to oil product requirements.

[0049] As a preferred embodiment, the addition amount of the antioxidant is 0.2%±0.05% of the mass of the Class I transformer oil base oil, including but not limited to any one of 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, 0.20%, 0.21%, 0.22%, 0.23%, 0.24%, and 0.25%, or a numerical range consisting of any two of them.

[0050] As a preferred embodiment, the Class I transformer oil of the present invention has the following properties: oxidation stability at 120°C ≥500h, total acid value <0.22mgKOH / g, sludge <0.0038%, and dielectric loss factor at 90°C <0.035.

[0051] The fourth aspect of the present invention is to provide the use of the Class I transformer oil base oil as described in the second aspect or the Class I transformer oil as described in the third aspect in transformers; it can be understood that any oil product or technical process in the field of transformers obtained based on the Class I transformer oil base oil or the Class I transformer oil can be used as an implementation method of this aspect.

[0052] Example 1

[0053] This embodiment uses CNOOC Suizhong 36-1 regular second-line distillate oil produced by a certain refinery as raw material.

[0054] The raw oil is mixed with hydrogen and then passed through the hydrotreating catalyst of the first hydrogenation reactor, the hydrodecondensation catalyst of the second hydrogenation reactor, and the supplementary refining catalyst of the second hydrogenation reactor in sequence. The feed volume space velocity at the raw material end is controlled to be 1.0 h -1 , hydrogen-oil volume ratio is 800:1, and the hydrogen partial pressure of the reactor system is 7.5MPa; among them, the catalysts for hydrotreating, hydrodecondensation and supplementary refining are tungsten-nickel hydrogenation catalyst, nickel-containing molecular sieve catalyst, molybdenum-tungsten-nickel hydrogenation catalyst, and the tungsten-nickel hydrogenation catalyst is a hydrotreating catalyst with the brand ZQC-25 of CNOOC Chemical and New Materials Science Research Institute; the filling volume ratio of the three catalysts for hydrotreating, hydrodecondensation and supplementary refining is 1:1.8:2.1; the average reaction temperatures of the three catalysts are 350℃, 340℃ and 345℃ respectively.

[0055] The product after the second hydrogenation reactor is separated by gas-liquid separation and rectification, and the product is extracted from the side line of the vacuum tower at a temperature of >260°C as the type I transformer oil base oil of this embodiment.

[0056] 2,6-di-tert-butyl-p-cresol was added to the obtained type I transformer oil base oil in an amount of 0.2 wt.%, to obtain the type I transformer oil of this embodiment.

[0057] It should be added that the preparation methods of the two catalysts used in this embodiment are as follows:

[0058] (1) Nickel-based molecular sieve-containing catalyst:

[0059] (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.

[0060] (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 of this embodiment.

[0061] (2) Molybdenum-tungsten-nickel type hydrogenation catalyst:

[0062] (a) Weigh the pore volume of aluminum sulfate produced by 1.095 mL / g and the specific surface area of ​​328 m 2 / g pseudo-boehmite 500g (dry basis 71%), 18.4g nitric acid (65%), 10g sesbania powder and 694g deionized water are added into a roller and rolled and mixed. After extrusion into strips, the strips are dried at 120°C for 10h and then calcined at 750°C for 3h to obtain a clover-shaped catalyst carrier for standby use.

[0063] (b) 90 mL of calcium nitrate solution containing 0.02 g / mL of calcium oxide was prepared, 100 g of the above carrier was weighed and impregnated with the solution, and then dried at 140° C. for 8 h to obtain carrier A for standby use.

[0064] (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 Mo-Ni series catalyst in the catalyst is 40%.

[0065] 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%.

[0066] (d) 52.8 mL of the Mo-Ni-P solution was taken, 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.

[0067] (e) Weigh 100 g of the calcium-containing carrier, impregnate the carrier with 88 mL of the water-in-oil microemulsion, dry at 120° C. for 8 h, and then calcine at 450° C. for 3 h to obtain a catalyst semi-finished product.

[0068] (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 of this example.

[0069] Example 2

[0070] This embodiment uses CNOOC Qinhuangdao 32-6 regular second-line distillate oil produced by a certain refinery as raw material.

[0071] This embodiment is substantially the same as embodiment 1, except that the average reaction temperatures of the three catalysts are 345° C., 340° C., and 340° C., respectively.

[0072] Example 3

[0073] This embodiment is basically the same as Embodiment 1, except that the hydroprocessing catalyst (tungsten-nickel type hydrogenation catalyst) is replaced by a molybdenum-nickel type hydrogenation catalyst (purchased from CNOOC Chemical and New Materials Science Research Institute, brand ZQC-25).

[0074] Example 4

[0075] This embodiment is basically the same as Embodiment 1, except that the hydroprocessing catalyst (tungsten-nickel type hydrogenation catalyst) is replaced by a molybdenum-cobalt type hydrogenation catalyst (CNOOC Chemical and New Materials Science Research Institute, brand ZQC-27).

[0076] As shown in Tables 1 and 2 below, the property parameters of the Type I transformer oil base oil and Type I transformer oil prepared in each embodiment are provided respectively.

[0077] Table 1 Properties of Type I Transformer Oil Base Oil

[0078] Example 1 Example 2 Example 3 Example 4 Transformer oil yield, % 97.7 97.3 96.3 96.1 <![CDATA[Density (20 °C), kg / m 3 > 0.8865 0.8833 0.8852 0.8869 Sulfur content, ppm 63 97 8.3 8.1 Nitrogen content, ppm 15 29 1.9 2.1 Closed cup flash point, ℃ 141 139 142 19 Pour point, ℃ ＜-57 ＜-57 ＜-57 ＜-57 CA value, % 4.3 4.6 3.6 4.1 Monocyclic aromatic hydrocarbons, % 15.0 16.3 12.5 13.2 Bicyclic aromatic hydrocarbons, % 3.0 3.2 2.1 2.3 Tricyclic aromatic hydrocarbons, % 0.2 0.2 0.1 0.1 Total aromatics, % 18.2 19.7 14.7 15.6

[0079] Table 2 Properties of Type I Transformer Oil

[0080]

[0081]

[0082] Test example

[0083] (1) Example 1 was used to conduct an experiment. The production unit system was operated continuously for 120 days. The transformer oil base oil produced was sampled every 48 hours to analyze its aromatic content and pour point. The periodic data were obtained as follows: Figure 1 shown.

[0084] (2) The main factor restricting the long-term operation of industrial devices is the rapid growth of the device pressure drop. 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 bed permeability, that is, the quality of logistics distribution. The three catalysts in the embodiment of the present invention 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 device.

[0085] In order to verify that the stability of the catalyst of the present invention is conducive to the long-term operation of the device, the stability of the catalyst of the present invention is verified in a medium-sized hydrogenation test device similar to the process flow of the industrial device. Taking Example 1 and Example 2 as examples, the experiment was carried out, and the device was continuously operated for 2600 hours. The static pressure drop at the inlet (R1) of the first hydrogenation reactor and the outlet (R2) of the second hydrogenation reactor was measured at the 300th hour and the 2600th hour, and the periodic data were obtained as shown in Table 3.

[0086] Table 3 Stability of catalyst

[0087]

[0088]

[0089] Although the present invention has been illustrated and described with specific embodiments, it should be appreciated that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Those skilled in the art should understand that the technical solutions described in the above embodiments may be modified, or some or all of the technical features thereof may be replaced by equivalents without departing from the spirit and scope of the present invention. However, these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention. Therefore, this means that all such replacements and modifications within the scope of the present invention are included in the appended claims.

Claims

1. A method for preparing transformer oil base oil from naphthenic distillate oil, characterized in that: The steps include: The light cycloalkane fraction oil is subjected to hydrogenation treatment, hydrodecondensation, additional refining and fractionation treatment in sequence, and the fraction with a temperature of more than 260° C. is taken to obtain a Class I transformer oil base oil; Wherein, the reaction pressure of the method is 7.5MPa and the catalyst in the method is a non-precious metal catalyst.

2. The method according to claim 1, characterized in that The temperature of the hydrotreatment is 280°C to 380°C; And / or, the temperature of the hydrocondensation is 300°C to 380°C; And / or, the temperature of the supplementary refining is 300°C to 380°C.

3. The method according to claim 1, characterized in that The hydrogenation catalyst comprises at least one of a molybdenum-nickel hydrogenation catalyst, a tungsten-nickel hydrogenation catalyst, a molybdenum-cobalt hydrogenation catalyst or a molybdenum-tungsten-nickel hydrogenation catalyst; Preferably, the catalyst for the hydrogenation treatment is a tungsten-nickel type hydrogenation catalyst.

4. The method according to claim 1, characterized in that: The hydrodecondensation catalyst comprises at least one of a nickel-type molecular sieve-containing catalyst, a molybdenum-nickel-type molecular sieve-containing catalyst, a tungsten-nickel-type molecular sieve-containing catalyst or a molybdenum-tungsten-nickel-type molecular sieve-containing catalyst; Preferably, the catalyst for the hydrodecondensation is a nickel-type molecular sieve-containing catalyst.

5. The method according to claim 1, characterized in that: The supplementary refined catalyst includes at least one of a molybdenum-nickel type hydrogenation catalyst, a tungsten-nickel type hydrogenation catalyst, a molybdenum-cobalt type hydrogenation catalyst or a molybdenum-tungsten-nickel type hydrogenation catalyst; Preferably, the supplementary refined catalyst is one or both of a tungsten-nickel type hydrogenation catalyst and a molybdenum-tungsten-nickel type hydrogenation catalyst.

6. The method according to claim 1, characterized in that In the hydrotreatment, the hydrodecondensation and the supplementary refining, the volume ratio of hydrogen to oil product is independently selected from (600-1500):1; And / or, in the hydroprocessing, the hydrodecondensation, and the supplementary refining, the volume space velocity is independently selected from 0.2h -1 ~2.5h -1 .

7. The method according to claim 1, characterized in that The yield of the Class I transformer oil base oil is greater than 96%.

8. A Class I transformer oil base oil, characterized in that: The oil is prepared by the method for preparing transformer oil base oil with cycloalkane distillate oil as claimed in any one of claims 1 to 7.

9. A Class I transformer oil, characterized in that: Comprising the Class I transformer oil base oil as described in claim 8.

10. Use of the Class I transformer oil base oil according to claim 8 or the Class I transformer oil according to claim 9 in transformers.

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