Hydrogenated terphenyl heat transfer oil and its preparation method

Abstract

This invention relates to the field of heat transfer oils and discloses a hydrogenated terphenyl heat transfer oil and its preparation method. The hydrogenated terphenyl heat transfer oil contains cyclohexylbiphenyl, dicyclohexylbenzene, tercyclohexane, and dicyclohexylbenzene. Based on the total amount of the hydrogenated terphenyl heat transfer oil, the content of cyclohexylbiphenyl, dicyclohexylbenzene, tercyclohexane, and dicyclohexylbenzene is not less than 75% by weight, preferably not less than 80% by weight. This invention uses a solid acid catalyst to alkylate biphenyl with cyclohexene and / or cyclohexanol, followed by separation and partial hydrogenation using a hydrogenation catalyst. This results in a high yield of hydrogenated terphenyl, low energy consumption in the preparation process, and the ability to obtain a hydrogenated terphenyl heat transfer oil with a low pour point, which can replace traditional hydrogenated terphenyl products.

Description

Technical Field

[0001] This invention relates to the field of heat transfer oils, specifically to a hydrogenated terphenyl heat transfer oil and its preparation method. Background Technology

[0002] Hydrogenated terphenyl-based heat transfer oil refers to a mixture of C18 aromatics with low pour points and high boiling points, composed of the products of partial hydrogenation of terphenyl. It features good high-temperature stability, low vapor pressure, low coking tendency, and low toxicity, making it the most widely used synthetic high-temperature heat transfer oil. Hydrogenated terphenyl-based heat transfer oil is mainly used in industries such as petrochemicals, synthetic fibers, synthetic resins, wood processing, nuclear fuel processing, pharmaceuticals, and printing and dyeing. In recent years, with the large-scale investment in photovoltaic power generation and air energy storage projects, the market demand for hydrogenated terphenyl-based high-temperature heat transfer oil has been increasing.

[0003] The traditional method for preparing hydrogenated terphenyl involves using benzene as a raw material, which is then subjected to high-temperature treatment to produce terphenyl, followed by further hydrogenation. Currently, most domestic and international methods utilize tubular cracking, where terphenyl is a byproduct, resulting in low yields and high energy consumption due to the cracking temperature reaching 800℃. Furthermore, the traditional high-temperature benzene cracking method for producing hydrogenated terphenyl typically results in a high pour point. In particular, the pour point of hydrogenated terphenyl heat transfer oil also increases after use. Therefore, improving the yield of hydrogenated terphenyl, developing low-energy-consumption technologies, and preparing hydrogenated terphenyl heat transfer oils with high thermal stability are of significant importance. Summary of the Invention

[0004] The purpose of this invention is to overcome the problems of low yield, high energy consumption in preparation, and poor thermal stability of hydrogenated terphenyl in the existing technology, and to provide a hydrogenated terphenyl heat transfer oil and its preparation method.

[0005] To achieve the above objectives, the present invention provides a hydrogenated terphenyl heat transfer oil containing cyclohexylbiphenyl, dicyclohexylbenzene, tercyclohexane, and dicyclohexylbenzene, wherein, based on the total amount of the hydrogenated terphenyl heat transfer oil, the content of cyclohexylbiphenyl, dicyclohexylbenzene, tercyclohexane, and dicyclohexylbenzene is not less than 75% by weight, preferably not less than 80% by weight.

[0006] Another aspect of the present invention provides a method for preparing hydrogenated terphenyl heat transfer oil, the method comprising the following steps:

[0007] (1) In the presence of a solid acid catalyst, biphenyl is alkylated with cyclohexene and / or cyclohexanol to generate a mixture containing cyclohexyl biphenyl;

[0008] (2) Remove the C6-C12 components from the mixture containing cyclohexylbiphenyl to obtain cyclohexylbiphenyl;

[0009] (3) In the presence of a hydrogenation catalyst, the cyclohexylbiphenyl is partially hydrogenated to obtain hydrogenated terphenyl heat transfer oil.

[0010] This invention employs a solid acid catalyst to carry out an alkylation reaction of biphenyl with cyclohexene and / or cyclohexanol, followed by separation and partial hydrogenation reaction via a hydrogenation catalyst. This results in a high yield of hydrogenated terphenyl, low energy consumption in the preparation process, and the product meets the relevant requirements stipulated in national standards. Detailed Implementation

[0011] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0012] The present invention provides a hydrogenated terphenyl heat transfer oil containing cyclohexylbiphenyl, dicyclohexylbenzene, tercyclohexane, and dicyclohexylbenzene, wherein, based on the total amount of the hydrogenated terphenyl heat transfer oil, the content of cyclohexylbiphenyl, dicyclohexylbenzene, tercyclohexane, and dicyclohexylbenzene is not less than 75% by weight, preferably not less than 80% by weight.

[0013] According to the present invention, preferably, based on the total amount of hydrogenated terphenyl heat transfer oil, the content of cyclohexylbiphenyl is 20-80% by weight, the content of dicyclohexylbenzene is 10-50% by weight, the content of tercyclohexane is 1-25% by weight, and the content of dicyclohexylbenzene is 1-20% by weight.

[0014] According to a preferred embodiment of the present invention, based on the total amount of hydrogenated terphenyl heat transfer oil, the content of cyclohexylbiphenyl is 30-60% by weight, the content of dicyclohexylbenzene is 25-45% by weight, the content of tercyclohexane is 5-15% by weight, and the content of dicyclohexylbenzene is 2-10% by weight.

[0015] The hydrogenated terphenyl heat transfer oil of the present invention preferably contains specific amounts of cyclohexylbiphenyl, dicyclohexylbenzene, tercyclohexane and dicyclohexylbenzene, resulting in a richer product composition. The combination of multiple components gives the hydrogenated terphenyl heat transfer oil the advantages of low pour point, good thermal stability and low degradation rate.

[0016] According to the present invention, any heat transfer oil that meets the foregoing requirements can be used in the present invention, and there are no special requirements for the source of each component. For the present invention, it is preferred that the cyclohexylbiphenyl is derived from the alkylation reaction of biphenyl and cyclohexene; it is also preferred that the dicyclohexylbenzene, tercyclohexane, and dicyclohexylbenzene are derived from the partial hydrogenation reaction of cyclohexylbiphenyl. This preferred embodiment can effectively reduce energy consumption, giving the hydrogenated terphenyl heat transfer oil of the present invention the advantages of wide availability and low cost.

[0017] Another aspect of the present invention provides a method for preparing hydrogenated terphenyl heat transfer oil, the method comprising the following steps:

[0018] (1) In the presence of a solid acid catalyst, biphenyl is alkylated with cyclohexene and / or cyclohexanol to generate a mixture containing cyclohexyl biphenyl;

[0019] (2) Remove the C6-C12 components from the mixture containing cyclohexylbiphenyl to obtain cyclohexylbiphenyl;

[0020] (3) In the presence of a hydrogenation catalyst, the cyclohexylbiphenyl is partially hydrogenated to obtain hydrogenated terphenyl heat transfer oil.

[0021] This invention employs a solid acid catalyst to alkylate biphenyl with cyclohexene and / or cyclohexanol, followed by separation and hydrogenation via a hydrogenation catalyst. This results in a high yield of hydrogenated terphenyl. Compared to the existing high-temperature cracking method for preparing hydrogenated terphenyl, this invention significantly reduces energy consumption, minimizes compositional differences between products, and improves the stability of industrial production.

[0022] According to the present invention, preferably, the solid acid catalyst comprises a molecular sieve and / or a heteropoly acid and a binder.

[0023] In this invention, the use of molecular sieves and / or heteropolyacids in the solid acid catalyst can achieve the invention's objective. Preferably, the solid acid catalyst comprises a molecular sieve with a nanostructure and a binder. This preferred embodiment is more conducive to the contact between biphenyl macromolecules and cyclohexene / cyclohexanol, improving their reaction efficiency; it also facilitates the diffusion of larger product macromolecules from the catalyst, avoiding secondary reactions, reducing byproducts, and increasing yield.

[0024] According to the present invention, the molecular sieve is preferably a molecular sieve with a nanoscale grain size. Preferably, the molecular sieve is selected from at least one of SRZ-21, nano-Y, and nano-beta zeolite, and more preferably thin-layered SRZ-21 and / or nano-beta zeolite. The grain size of the thin-layered SRZ-21 molecular sieve is preferably 2-6 nm. This preferred embodiment is more conducive to improving reaction efficiency and reducing side reactions. The nano-molecular sieve used in the present invention can be prepared by conventional methods. For example, the SRZ-21 molecular sieve can be prepared by the method of Example 1 in patent CN105439802B; the nano-beta zeolite can be prepared by the method of Example 1 in patent application CN106518600A; the nano-Y molecular sieve can be prepared by the methods provided in the literature (not limited to Materials Letters 60 (2006) 1131–1133, or Microporous and Mesoporous Materials 59 (2003) 13–28).

[0025] According to the present invention, the heteropoly acid is preferably a relatively strong acid, and more preferably, the heteropoly acid is selected from phosphomolybdic acid and / or germanomolybdic acid, and more preferably phosphomolybdic acid.

[0026] According to the present invention, the range of the adhesives is relatively wide. Preferably, the adhesive is selected from at least one of alumina, silica, clay and diatomaceous earth, and more preferably alumina.

[0027] According to the present invention, preferably, based on the total amount of the solid acid catalyst, the content of molecular sieve and / or heteropoly acid is 50-70% by weight, and the content of binder is 30-50% by weight; more preferably, the content of molecular sieve and / or heteropoly acid is 60-70% by weight, and the content of binder is 30-40% by weight.

[0028] The present invention does not particularly limit the preparation method of the solid acid catalyst, as long as the above-mentioned alkylation reaction can be carried out, any method known in the art can be used.

[0029] According to a preferred embodiment of the present invention, when the solid acid catalyst comprises a molecular sieve and a binder, the preparation method of the solid acid catalyst includes: mixing molecular sieve powder and binder into a mold, then drying and calcining; and then subjecting the calcined product to ammonium exchange. The drying, calcination, and ammonium exchange can all be carried out under conventional conditions. Preferably, the drying includes drying at 100-150°C for 5-24 hours. Preferably, the calcination includes calcining at 450-650°C for 3-8 hours. Preferably, the ammonium exchange includes exchanging the calcined product with an ammonium salt solution at 40-100°C for 1-24 hours, washing with deionized water, drying at 100-150°C for 5-24 hours, and calcining at 450-650°C for 3-8 hours. Preferably, the ammonium salt solution comprises an aqueous solution prepared from one or any combination of ammonium nitrate, ammonium chloride, ammonium sulfate, and ammonium oxalate with deionized water. In the preparation process of the solid acid catalyst, the shaped sample can also be air-dried at room temperature and pressure for 1-24 hours before drying.

[0030] According to a preferred embodiment of the present invention, when the solid acid catalyst comprises a heteropoly acid and a binder, the preparation method of the solid acid catalyst includes: kneading the heteropoly acid and the binder into a mold, and then drying and calcining. Preferably, the drying includes drying at 100-150°C for 5-24 hours. Preferably, the calcination includes calcining at 350-550°C for 3-8 hours. During the preparation of the solid acid catalyst, the molded sample may also be air-dried at room temperature and pressure for 1-24 hours before drying.

[0031] According to the present invention, the solid acid catalyst can take any physical form, such as powder, granules, or molded form, such as spheres, flakes, strips, or clover shapes; preferably spheres or strips. These physical forms can be obtained in any manner conventionally known in the art, and there are no particular limitations.

[0032] According to the present invention, in the preparation of hydrogenated terphenyl heat transfer oil, preferably, the alkylation reaction conditions include: a reaction temperature of 80-200℃, a reaction pressure of 0.8-3.0 MPa, a molar ratio of biphenyl to cyclohexene of 1-6:1, and a cyclohexene mass hourly space velocity of 0.1-2.0 h⁻¹. -1 Specifically, for example, the reaction temperature is preferably 150-190°C; the reaction pressure is preferably 1.0-2.5 MPa; the molar ratio of biphenyl to cyclohexene is preferably 2-5; and the cyclohexene mass hourly space velocity is preferably 0.8-1.5 h⁻¹. -1 .

[0033] According to the present invention, there are no particular limitations on the method for removing the C6-C12 components from the mixture containing cyclohexylbiphenyl in step (2). Preferably, vacuum distillation is used to remove the C6-C12 components from the mixture containing cyclohexylbiphenyl. The C6-C12 components mainly include cyclohexene, biphenyl raw materials, and small amounts of other isomers, such as methylcyclopentane.

[0034] According to a preferred embodiment of the present invention, the conditions for vacuum distillation include: a temperature of 180-300°C and a vacuum degree of 2-10 kPa. Specifically, for example, the temperature can preferably be 220-260°C; and the vacuum degree can preferably be 3-5 kPa.

[0035] According to the present invention, the selection range of the hydrogenation catalyst is relatively wide, as long as it can achieve the hydrogenation of cyclohexylbiphenyl. Preferably, the hydrogenation catalyst comprises a support and a metal active component.

[0036] According to a preferred embodiment of the present invention, the carrier is selected from at least one of alumina and silicon oxide.

[0037] According to the present invention, the active metallic component is selected from at least one of noble metals. The noble metal has the conventional meaning in the art, and is selected from at least one of gold, silver, and platinum group metals (ruthenium, rhodium, palladium, osmium, iridium, platinum).

[0038] According to a preferred embodiment of the present invention, the active metal component is at least one of Pd, Pt and Ru.

[0039] According to a preferred embodiment of the present invention, based on the total amount of hydrogenation catalyst, the content of the support is 95-99.9% by weight, and the content of the metal active component is 0.1-5% by weight. More preferably, based on the total amount of hydrogenation catalyst, the content of the support is 96-98% by weight, and the content of the metal active component is 0.5-4% by weight.

[0040] This invention does not particularly limit the preparation method of the hydrogenation catalyst; for example, it can be a conventional impregnation method. Specifically, it preferably includes: loading the metal active component onto an alumina support in the form of a precursor salt solution, optionally drying it at room temperature and pressure for 1-24 hours, followed by drying and calcination. The drying preferably includes drying at 100-150°C for 5-24 hours, and the calcination preferably includes calcining at 450-650°C for 3-8 hours. Before use, the hydrogenation catalyst also includes reduction, preferably carried out under a hydrogen atmosphere at a reduction temperature of 100-500°C for 0.5-12 hours and a hydrogen volume hourly space velocity of 100-600 h⁻¹. -1The precursor salt can be at least one of the water-soluble compounds corresponding to noble metals. The present invention does not have any particular limitation on this, and those skilled in the art can make appropriate selections.

[0041] According to the present invention, the hydrogenation catalyst can take any physical form, such as powder, granules, or molded form, such as spheres, flakes, strips, or clover shapes; preferably spheres or strips. These physical forms can be obtained in any manner conventionally known in the art, and there is no particular limitation.

[0042] According to a preferred embodiment of the present invention, the conditions for the partial hydrogenation include: a reaction temperature of 80-260°C, a reaction pressure of 0.8-3.0 MPa, and a cyclohexylbiphenyl mass hourly space velocity of 0.1-2.0 h⁻¹. -1 The volume hourly space velocity of hydrogen is 30-100 h⁻¹. -1 Specifically, for example, the reaction temperature is preferably 150-250°C, more preferably 180-250°C; the reaction pressure is preferably 1.0-2.5 MPa; and the cyclohexylbiphenyl mass hourly space velocity is preferably 0.8-1.5 h⁻¹. -1 .

[0043] The preparation process of the hydrogenated terphenyl heat transfer oil of the present invention is simple and energy-efficient. In actual industrial production, the product composition varies little and the stability is good. It can obtain hydrogenated terphenyl heat transfer oil with a low pour point and can replace traditional hydrogenated terphenyl products.

[0044] The advantages of the present invention are described in detail below through examples, but are not limited to the scope of protection of the present invention.

[0045] The following preparation examples illustrate the preparation of solid acid catalysts.

[0046] Preparation Example 1-1

[0047] Take 60 g of thin-layer SRZ-21 molecular sieve powder, then take 40 g of alumina to compound it together, knead and shape it into strips, dry at 120℃ for 12 hours, and then calcine at 400℃ for 5 hours. Exchange the above-shaped sample with ammonium chloride solution at 80℃ for 8 hours, wash with deionized water, dry at 150℃ for 5 hours, and calcine at 500℃ for 6 hours. The desired solid acid catalyst G1 is obtained.

[0048] Preparation Examples 1-2

[0049] Take 60 g of nano-beta powder, then take 40 g of alumina and combine them together. Knead and shape into strips, dry at 120°C for 12 hours, and then calcine at 400°C for 5 hours. Exchange the above-shaped sample with ammonium chloride solution at 80°C for 8 hours, wash with deionized water, dry at 150°C for 5 hours, and calcine at 500°C for 6 hours. The desired solid acid catalyst G2 is obtained.

[0050] Preparation Examples 1-3

[0051] Take 60 g of nano-Y powder, then take 40 g of alumina to compound it together, knead and shape it into strips, dry at 120°C for 12 hours, and then calcine at 400°C for 5 hours. Exchange the above-shaped sample with ammonium chloride solution at 80°C for 8 hours, wash with deionized water, dry at 150°C for 5 hours, and calcine at 500°C for 6 hours. The desired solid acid catalyst G3 is obtained.

[0052] Preparation Examples 1-4

[0053] Take 35 g of SRZ-21 powder and 30 g of nano-beta powder, then add 35 g of alumina and combine them together. Knead the mixture, shape it into strips, dry it at 120°C for 12 hours, and then calcine it at 400°C for 5 hours. Exchange the shaped sample with ammonium chloride solution at 80°C for 8 hours, wash it with deionized water, dry it at 150°C for 5 hours, and then calcine it at 500°C for 6 hours. This yields the desired solid acid catalyst G4.

[0054] Preparation Examples 1-5

[0055] Take 60 grams of phosphomolybdic acid powder, then take 40 grams of alumina and combine them together, knead, shape into strips, dry at 120°C for 12 hours, and then calcine at 400°C for 5 hours. The desired solid acid catalyst G5 is obtained.

[0056] Preparation Examples 1-6

[0057] Take 70 grams of phosphomolybdic acid powder, then take 30 grams of alumina and combine them together, knead, shape into strips, dry at 120°C for 12 hours, and then calcine at 400°C for 5 hours. The desired solid acid catalyst G6 is obtained.

[0058] The following preparation examples illustrate the preparation of hydrogenation catalysts.

[0059] Preparation Example 2-1

[0060] 100 g of alumina support was loaded with 0.5 g of Pd and dried at 120 °C for 12 hours, followed by calcination at 550 °C for 5 hours. The resulting sample was then reduced at 150 °C for 3 hours at a hydrogen hourly space velocity (HHSV) of 300 h⁻¹. -1 The desired hydrogenation catalyst H1 is thus obtained.

[0061] Preparation Example 2-2

[0062] 100 g of alumina support was loaded with 1.0 g of Pd, dried at 120 °C for 12 hours, and calcined at 550 °C for 5 hours. The resulting sample was then reduced at 150 °C for 3 hours at a hydrogen hourly space velocity (HHSV) of 300 h⁻¹. -1 The desired hydrogenation catalyst H2 is thus obtained.

[0063] Preparation Examples 2-3

[0064] 100 g of alumina support was loaded with 2.0 g of Pt, dried at 120 °C for 12 hours, and calcined at 550 °C for 5 hours. The resulting sample was then reduced at 180 °C for 3 hours at a hydrogen volume hourly space velocity (HHSV) of 300 h⁻¹. -1 The desired hydrogenation catalyst H3 is thus obtained.

[0065] Preparation Examples 2-4

[0066] 100 g of alumina support was loaded with 3.0 g of Ru and dried at 120 °C for 12 hours, followed by calcination at 550 °C for 5 hours. The resulting sample was then reduced at 250 °C for 3 hours at a hydrogen hourly space velocity (HHSV) of 300 h⁻¹. -1 The desired hydrogenation catalyst H4 is thus obtained.

[0067] Example 1

[0068] (1) Take 10 g of the above solid acid catalyst G1 and carry out the alkylation reaction of biphenyl with cyclohexene in a fixed-bed reactor. The reaction conditions are: cyclohexene mass hourly space velocity (HHSV) of 0.5 h⁻¹. -1 The molar ratio of biphenyl to cyclohexene was 4. The reaction temperature was 140℃, the reaction pressure was 2.0 MPa, and the reaction time was 1000 hours. The reaction mixture was collected, and the alkylation reaction results are shown in Table 1.

[0069] (2) Take 100 grams of the mixture obtained in step (1) and put it into a vacuum distillation apparatus. Reduce the system pressure to 3 kPa and raise the temperature of the column bottom to 245°C to distill off the C6-C12 components in the mixture. The composition of the column bottom components obtained by distillation is shown in Table 2.

[0070] (3) The hydrogenation reaction of hydrogenation catalyst H1 and cyclohexylbiphenyl obtained in the reactor of step (2) was carried out in a fixed-bed reactor. The catalyst loading was 10 g, and the reaction conditions were: the mass hourly space velocity of cyclohexylbiphenyl was 1.0 h⁻¹. -1 The volume hourly space velocity of hydrogen is 60 h⁻¹. -1 The reaction temperature was 200℃ and the reaction pressure was 2.0 MPa. The results of the hydrogenation reaction are shown in Table 3.

[0071] According to the relevant requirements for L-QD340 in the national standard GB 23971, the product specifications of the obtained high-temperature heat transfer oil are shown in Table 4.

[0072] Examples 2-6

[0073] The method is the same as in Example 1, except that the solid catalysts are G2-G6 respectively.

[0074] The alkylation reaction results are shown in Table 1, and the composition of the distillation column bottoms is shown in Table 2.

[0075] Example 7

[0076] The method is the same as in Example 1, except that the hydrogenation catalyst is H2, the obtained high-temperature heat transfer oil is S7, and the composition of the hydrogenation reaction products is shown in Table 3.

[0077] Example 8

[0078] The method is the same as in Example 1, except that the hydrogenation catalyst is H3, the obtained high-temperature heat transfer oil is S8, and the composition of the hydrogenation reaction products is shown in Table 3.

[0079] Example 9

[0080] The method is the same as in Example 1, except that the hydrogenation catalyst is H4, the obtained high-temperature heat transfer oil is S9, and the composition of the hydrogenation reaction products is shown in Table 3.

[0081] Example 10

[0082] The method is the same as in Example 1, except that the alkylation reaction conditions in step (1) are a cyclohexene mass hourly space velocity of 0.8 h⁻¹. -1 The molar ratio of biphenyl to cyclohexene was 5. The reaction temperature was 160℃, the reaction pressure was 2.0 MPa, and the reaction time was 1000 hours. The reaction mixture was collected, and the alkylation reaction results are shown in Table 1.

[0083] Example 11

[0084] The method is the same as in Example 1, except that in step (2), the reduced pressure distillation conditions are reduced to 6 kPa and the temperature of the distillation vessel is increased to 265°C.

[0085] Example 12

[0086] The method is the same as in Example 1, except that the hydrogenation reaction conditions in step (3) are: the mass hourly space velocity (HHSV) of cyclohexylbiphenyl is 1.2 h⁻¹. -1 The volume hourly space velocity of hydrogen is 50 h⁻¹. -1 The reaction temperature was 200℃ and the reaction pressure was 2.0 MPa. The results of the hydrogenation reaction are shown in Table 3.

[0087] Table 1. Results of the alkylation reaction of biphenyl with cyclohexene (wt%)

[0088]

[0089]

[0090] Table 2

[0091]

[0092] Table 3. Results of the hydrogenation reaction of cyclohexylbiphenyl (wt%)

[0093]

[0094] Table 4. Various test indicators of the product obtained by this invention

[0095]

[0096] As can be seen from the results in Table 4, compared with conventionally prepared hydrogenated terphenyl, the hydrogenated terphenyl heat transfer oil of the present invention has a lower pour point, lower requirements for ambient temperature, and a wider range of applications. In addition, the product has good thermal stability and low deterioration rate. After heating at 340℃ for 1000 hours, the deterioration rate is only 5.4%, which improves its stability at high temperatures and has a longer expected service life. Compared with existing heat transfer oil products, its performance indicators are comparable to or even better, and it has better application prospects.

[0097] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A hydrogenated terphenyl heat transfer oil, comprising: cyclohexylbiphenyl, dicyclohexylbenzene, tercyclohexane, and dicyclohexylbenzene, wherein, based on the total amount of the hydrogenated terphenyl heat transfer oil, the content of cyclohexylbiphenyl is 30-60% by weight, the content of dicyclohexylbenzene is 25-45% by weight, the content of tercyclohexane is 5-15% by weight, and the content of dicyclohexylbenzene is 2-10% by weight; The hydrogenated terphenyl heat transfer oil is prepared by the following method. (1) In the presence of a solid acid catalyst, biphenyl is alkylated with cyclohexene to generate a mixture containing cyclohexylbiphenyl; the solid acid catalyst comprises a molecular sieve and a binder; The molecular sieve is SRZ-21 molecular sieve; (2) Remove the C6-C12 components from the mixture containing cyclohexylbiphenyl to obtain cyclohexylbiphenyl; (3) In the presence of a hydrogenation catalyst, the cyclohexylbiphenyl is partially hydrogenated to obtain hydrogenated terphenyl heat transfer oil; the conditions for the partial hydrogenation include: The reaction temperature was 200-260℃, the reaction pressure was 0.8-3.0 MPa, and the mass hourly space velocity (HHSV) of cyclohexylbiphenyl was 0.1-1.0 h⁻¹. -1 The volume hourly space velocity of hydrogen is 60-100 h⁻¹. -1 .

2. A method for preparing the hydrogenated terphenyl heat transfer oil according to claim 1, the method comprising the following steps: (1) In the presence of a solid acid catalyst, biphenyl is alkylated with cyclohexene to generate a mixture containing cyclohexylbiphenyl; the solid acid catalyst comprises a molecular sieve and a binder; The molecular sieve is SRZ-21 molecular sieve; (2) Remove the C6-C12 components from the mixture containing cyclohexylbiphenyl to obtain cyclohexylbiphenyl; (3) In the presence of a hydrogenation catalyst, the cyclohexylbiphenyl is partially hydrogenated to obtain hydrogenated terphenyl heat transfer oil; the conditions for the partial hydrogenation include: The reaction temperature was 200-260℃, the reaction pressure was 0.8-3.0 MPa, and the mass hourly space velocity (HHSV) of cyclohexylbiphenyl was 0.1-1.0 h⁻¹. -1 The volume hourly space velocity of hydrogen is 60-100 h⁻¹. -1 .

3. The preparation method according to claim 2, wherein, The binder is selected from at least one of alumina, silica, clay and diatomaceous earth.

4. The preparation method according to claim 3, wherein, The binder is selected from aluminum oxide.

5. The preparation method according to claim 2, wherein, Based on the total amount of the solid acid catalyst, the molecular sieve content is 50-70% by weight, and the binder content is 30-50% by weight.

6. The preparation method according to claim 2, wherein, The alkylation reaction conditions include: a reaction temperature of 80-250℃, a reaction pressure of 0.8-3.0 MPa, a molar ratio of biphenyl to cyclohexene of 1-6:1, and a cyclohexene mass hourly space velocity of 0.1-2.0 h⁻¹. -1 .

7. The preparation method according to claim 2, wherein, In step (2), the C6-C12 components in the mixture containing cyclohexylbiphenyl are removed by vacuum distillation.

8. The preparation method according to claim 7, wherein, The conditions for vacuum distillation include: a temperature of 180-300℃ and a vacuum degree of 2-10kPa.

9. The preparation method according to claim 2, wherein, The hydrogenation catalyst includes a support and a metal active component; The carrier is selected from alumina and / or silicon oxide; The active metal component is selected from at least one of noble metals.

10. The preparation method according to claim 9, wherein, The active metal component is selected from at least one of Pd, Pt, and Ru.

11. The preparation method according to claim 9 or 10, wherein, Based on the total amount of hydrogenation catalyst, the content of support is 95-99.9% by weight, and the content of metal active component is 0.1-5% by weight.

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