Alkyl naphthalene, alkyl naphthalene lubricating oil and preparation method and application thereof

Abstract

The invention provides alkyl naphthalene lubricating oil as well as a preparation method and application thereof. According to the preparation method disclosed by the invention, naphthalene and byproduct olefin containing a branched chain structure are used as raw materials, solid acid is used as a catalyst, and alkylation reaction is performed to prepare the alkyl naphthalene lubricating oil. The preparation method has the advantages that the olefin conversion rate is high, the monosubstituted alkyl naphthalene selectivity is high, the reaction condition is mild, the device operation is simple, the branched olefin and the solid acid catalyst in the olefin byproduct can be recycled at high quality, the product is easy to separate, the corrosion to equipment is small, and the like. The alkyl naphthalene lubricating oil provided by the invention contains a branched chain structure obviously different from a long straight chain structure, and has excellent oxidation resistance.

Description

Technical Field

[0001] This invention belongs to the technical field of chemical synthesis, specifically relating to an alkyl naphthalene, an alkyl naphthalene lubricating oil, its preparation method, and its application. Background Technology

[0002] Alkyl naphthalenes have advantages such as high oxidation stability, high flash point, good thermal stability, and high safety. Among them, long-chain alkyl naphthalenes have superior additive solubility, demulsibility, and compatibility, and play an important role in the synthesis of lubricating oils. They are widely used in hydraulic oils, gear oils, heat transfer oils, transformer oils, refrigeration oils, compressor oils, liquid crystals, and other fields.

[0003] Alkylnaphthalenes are typically prepared by alkylation of long-chain α-olefins (either single-component or multi-component mixtures) with naphthalene under acid catalysis. This process follows a carbocation mechanism—the olefin, under the action of an acid catalyst, forms a carbocation, which rearranges to form an α-n-position carbocation, which then reacts with naphthalene to form an alkylnaphthalene. However, the oxidation stability and antioxidant properties of current alkylnaphthalenes remain relatively poor, indicating significant room for improvement.

[0004] Furthermore, existing alkylnaphthalene preparation processes typically use traditional Lewis acids as catalysts, which cause severe equipment corrosion, make it difficult or costly to separate the product from the catalyst, resulting in significant environmental pressure and failing to meet the requirements of green chemistry. Summary of the Invention

[0005] Therefore, the purpose of this invention is to provide an alkylnaphthalene, an alkylnaphthalene lubricating oil, a preparation method thereof, and its application. The first advantage of the preparation method of this invention is its excellent antioxidant properties. Other preferred embodiments also have the advantages of high olefin conversion rate, high selectivity for monosubstituted alkylnaphthalene, mild reaction conditions, simple equipment operation, high-quality recovery and utilization of branched olefins and solid acid catalysts from olefin by-products, easy separation from products, and low corrosion to equipment.

[0006] The first aspect of the present invention provides a method for preparing alkylnaphthalene.

[0007] The alkylnaphthalene preparation method of the present invention uses naphthalene and branched decene as raw materials, and obtains alkylnaphthalene through an alkylation reaction under the action of an acidic catalyst. Thus, the alkylnaphthalene prepared by the above method can improve the oxidation stability and antioxidant properties of alkylnaphthalene, and its oxidation stability is significantly improved compared to traditional Mobil lubricating oil AN12.

[0008] Optionally, a by-product olefin can be used to replace the branched decene as a raw material, wherein the by-product olefin is an olefin produced by the oligomerization of ethylene in the production process of 1-hexene; the by-product olefin contains at least one branched decene. Thus, directly using a by-product olefin to replace the branched decene as a raw material can better utilize the by-product olefin, better maintain and improve the oxidation stability and antioxidant properties of alkylnaphthalene, and reduce manufacturing costs. Further, the by-product olefin contains one or more branched decenes.

[0009] According to some embodiments of the present invention, the alkylnaphthalene lubricating oil is prepared by a batch reaction, specifically including the following steps:

[0010] (1) Naphthalene, by-product olefins and acidic catalyst are mixed to obtain a mixture;

[0011] (2) The mixture is subjected to alkylation reaction at a temperature of 140℃~160℃; thus, the intermittent reaction can improve the reaction conversion rate.

[0012] Optionally, the acidic catalyst is a solid acidic catalyst; thus, when an acidic catalyst is used, compared with the traditional method of using Lewis acids as catalysts, the present application uses a solid acidic catalyst, which causes less corrosion to equipment, and the product and catalyst are easy to separate with low separation costs, resulting in less environmental pressure and meeting the requirements of green chemistry.

[0013] Optionally, (3) the reaction product from step (2) is subjected to vacuum distillation. Preferably, the conditions for vacuum distillation include: a vacuum degree of 10–30 mmHg and collection of the fraction at 240–260 °C. Thus, vacuum distillation under the above conditions can effectively improve the separation effect and separation purity.

[0014] After the reaction was completed, the product was dissolved and diluted with dichloromethane and its composition was analyzed by gas chromatography.

[0015] In some embodiments of the present invention, the by-product olefin is a by-product olefin from the ethylene oligomerization process in the 1-hexene production process.

[0016] According to some embodiments of the present invention, the by-product olefin comprises one or more branched decenes. Of course, the by-product olefin in this application is not limited to this; it can also be other by-product olefins containing branched decenes in a relatively high content. In this embodiment, "relatively high content" refers to a content of 50% or more, preferably 60% or more, more preferably 70% or more, preferably 80% or more, preferably 90% or more, and preferably 98% or more. That is, the by-product olefin is a by-product of the olefin polymerization unit, its main component is decene, and its content is ≥98%.

[0017] According to some embodiments of the present invention, the alkylnaphthalene is a monosubstituted alkylnaphthalene, and / or the mixing conditions in step (1) include a temperature of 70°C to 90°C, and / or the alkylation reaction time in step (2) is 1 to 3 hours. Thus, by using the above-mentioned temperature and reaction time, the conversion rate can be improved, and the reaction is relatively mild.

[0018] According to some embodiments of the present invention, the solid acid catalyst is a Y-type molecular sieve with a silicon-to-aluminum ratio of 10:1 to 20:1, and / or, based on the total mass of by-product olefins and naphthalene, the catalyst dosage is 1 wt% to 3 wt%. Thus, compared to the conventional method of using Lewis acids as catalysts, the use of solid acid catalysts in this application results in less equipment corrosion, easier separation of products from catalysts with low separation costs, less environmental impact, and compliance with the requirements of green chemistry.

[0019] According to some preferred embodiments of the present invention, the solid acid catalyst is a Y-type molecular sieve with a silicon-to-aluminum ratio of 15:1 to 16:1, and / or, based on the total mass of by-product olefins and naphthalene, the amount of catalyst is 1 wt% to 3 wt%.

[0020] Optionally, the solid acid catalyst is a Y-type molecular sieve with a silicon-to-aluminum ratio of 15:1 and the amount of catalyst used is 1% to 3% of the total weight of the reactants. Thus, when the above-mentioned solid acid catalyst is used, especially when the amount of branched decene is ≥98% and the molar ratio of by-product olefin to naphthalene is 2:1 to 4:1, the alkyl naphthalene prepared in this way can improve the oxidation stability by about 2 times compared with the traditional Mobil lubricating oil AN12, exhibiting excellent oxidation stability and antioxidant properties.

[0021] In some preferred embodiments of the present invention, the content of the branched decene is ≥98% based on the total mass of the by-product olefins. According to some embodiments of the present invention, the molar ratio of the by-product olefins to naphthalene is 2:1 to 4:1.

[0022] According to some embodiments of the present invention, the branched decene comprises compounds of formula (1), formula (2), formula (3), formula (4), and formula (5);

[0023]

[0024]

[0025] In formula (1), R1 and R2 are each independently selected from C1-C6 alkyl groups, and the total number of carbon atoms in R1 and R2 is 7; in formula (2), R3 and R4 are each independently selected from C1-C5 alkyl groups, and the total number of carbon atoms in R3 and R4 is 6; in formula (3), R5 is a C4 alkyl group; in formula (4), R6 is a C4 alkyl group; in formula (5), R7 and R8 are each independently selected from C1-C7 alkyl groups, and the total number of carbon atoms in R7 and R8 is 8. Of course, the branched decene in this application is not limited to these.

[0026] According to some preferred embodiments of the present invention, the by-product olefin contains 26% of compound (1), 7% of compound (2), 18% of compound (3), 39% of compound (4), and 5% of compound (6). Specifically:

[0027]

[0028] According to some preferred embodiments of the present invention, the branched decene comprises, in molar amounts, 25% to 26% of compound (1), 6% to 7% of compound (2), 18% to 19% of compound (3), 39% to 40% of compound (4), and 4% to 5% of compound (5).

[0029] A second aspect of this invention provides an alkylnaphthalene or alkylnaphthalene lubricating oil prepared by the above-described preparation method. In other words, the alkylnaphthalene prepared in this application is not limited to use in the field of lubricating oils. For example, it can be used in high-temperature heat transfer oils, power capacitor oils, etc. Of course, other uses of alkylnaphthalene can be referenced from the prior art, and it is not limited to the prior art; as a formulation or product, it can also be further studied for use in other fields.

[0030] A third aspect of this invention provides an application of the aforementioned alkylnaphthalene lubricating oil in the fields of hydraulic oil, gear oil, heat transfer oil, transformer oil, refrigeration oil, compressor oil, and liquid crystal. However, it is not limited thereto. It should be understood that although this application provides some specific applications of lubricating oils, these are merely illustrative examples. When used as lubricating oils, the above examples should not be considered as limitations on the field of lubricating oils. On the contrary, any application that utilizes the properties of lubricating oils should be considered as its use as a lubricating oil.

[0031] The alkyl naphthalenes in this invention are mixtures of various isomers because their boiling points are close and separation is difficult. Their lubricating effect and performance are caused by the combined action of various alkyl naphthalenes.

[0032] This invention has the following advantages:

[0033] (1) The method for preparing alkyl naphthalene lubricating oil provided by the present invention uses naphthalene and by-product olefins containing branched structures as raw materials to solve the problem of high-level recycling of other structural olefins in the by-product olefins, except for long straight-chain olefins.

[0034] (2) The method for preparing alkylnaphthalene lubricating oil provided by this invention has an olefin conversion rate of 99.4% and a monosubstituted product selectivity of 93.1%, exhibiting high reaction efficiency, high selectivity, and high activity. The alkylnaphthalene lubricating oil prepared therefrom exhibits excellent antioxidant properties. In particular, the oxidative stability of alkylnaphthalene lubricating oil prepared from by-product olefins containing one or more branched decenes is twice that of Mobil lubricating oil AN12.

[0035] (3) The method for preparing alkyl naphthalene lubricating oil provided by the present invention uses Y-type molecular sieve solid acid catalyst, which has low corrosion to equipment, and the product and catalyst are easy to separate with low separation cost, low environmental pressure, and meets the requirements of green chemistry.

[0036] (4) The branched alkyl naphthalene lubricating oil prepared by the preparation method of the present invention has high antioxidant properties compared with existing long straight-chain alkyl naphthalene lubricating oils. In particular, the oxidation stability of the alkyl naphthalene lubricating oil prepared from by-product olefins containing one or more branched decenes is twice that of Mobil lubricating oil AN12. Attached Figure Description

[0037] Figure 1 This is a gas chromatogram of the reaction product in one embodiment;

[0038] Figure 2 The mass spectrum of the reaction product in one embodiment at a retention time of 3.825 is shown.

[0039] Figure 3 For C in the spectral library 10 H 20 The mass spectrum;

[0040] Figure 4 The mass spectrum of the reaction product in one embodiment at a retention time of 6.225 seconds is shown.

[0041] Figure 5 For C in the spectral library 10 Mass spectrum of H8;

[0042] Figure 6 The mass spectrum of the reaction product in one embodiment at a retention time of 10.242 seconds is shown.

[0043] Figure 7 For C in the spectral library 20 H 42 Mass spectrum of O;

[0044] Figure 8 The mass spectrum of the reaction product in one embodiment at a retention time of 11.100 seconds is shown.

[0045] Figure 9 For C in the spectral library 14 H 16 The mass spectrum;

[0046] Figure 10 The mass spectrum of the reaction product in one embodiment at a retention time of 11.400 is shown.

[0047] Figure 11 For C in the spectral library 14 H 16 The mass spectrum;

[0048] Figure 12 The mass spectrum of the reaction product in one embodiment at a retention time of 12.058 seconds is shown.

[0049] Figure 13 For C in the spectral library 20 H 28 The mass spectrum. Detailed Implementation

[0050] 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.

[0051] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0052] The present invention will be further described below with reference to specific embodiments, but this does not constitute any limitation on the present invention.

[0053] In the various embodiments and comparative examples of this invention, the catalyst used is a solid acid Y-type molecular sieve, specifically a USY-type molecular sieve, with a silicon-to-aluminum ratio of 15:1. The raw materials selected in this invention are naphthalene and by-product olefins, wherein the by-product olefins are by-product olefins from the ethylene oligomerization process in the production of 1-hexene, and the decene content in the by-product olefins is ≥98%. In the various embodiments and comparative examples of this invention, excess material from the reaction of naphthalene and by-product olefins is separated or removed by vacuum distillation.

[0054] Example 1

[0055] (1) Weigh out 100g of naphthalene, 27.4g of by-product olefin, and 2.5g of solid acid Y-type molecular sieve.

[0056] (2) The weighed naphthalene, by-product olefin and solid acid are heated to 80°C and stirred in a four-necked flask to obtain a mixture.

[0057] (3) The mixture was heated to 140°C for alkylation reaction, and samples were taken for analysis after 3 hours of reaction. After the reaction was completed, the product was dissolved and diluted with dichloromethane and its composition was analyzed by gas chromatography.

[0058] Example 2

[0059] (1) Weigh out 100g of naphthalene, 27.4g of by-product olefin, and 2.5g of solid acid Y-type molecular sieve.

[0060] (2) The weighed naphthalene, by-product olefin and solid acid are heated to 80°C and stirred in a four-necked flask to obtain a mixture.

[0061] (3) The mixture was heated to 150°C for alkylation reaction, and samples were taken for analysis after 3 hours of reaction.

[0062] Example 3

[0063] (1) Weigh out 100g of naphthalene, 27.4g of by-product olefin, and 2.5g of solid acid Y-type molecular sieve.

[0064] (2) The weighed naphthalene, by-product olefin and solid acid are heated to 80°C and stirred in a four-necked flask to obtain a mixture.

[0065] (3) Continue heating the mixture to 160°C for alkylation reaction. Take a sample for analysis after 3 hours of reaction.

[0066] Example 4

[0067] (1) Weigh out 100g of naphthalene, 36.5g of by-product olefins, and 2.7g of solid acid Y-type molecular sieve.

[0068] (2) The weighed naphthalene, by-product olefin and solid acid are heated to 80°C and stirred in a four-necked flask to obtain a mixture.

[0069] (3) The mixture was heated to 150°C for alkylation reaction, and samples were taken for analysis after 3 hours of reaction.

[0070] Example 5.

[0071] (1) Weigh 100g of naphthalene, 54.7g of by-product olefins, and 3.1g of solid acid Y-type molecular sieve.

[0072] (2) The weighed naphthalene, by-product olefin and solid acid are heated to 80°C and stirred in a four-necked flask to obtain a mixture.

[0073] (3) The mixture was heated to 150°C for alkylation reaction, and samples were taken for analysis after 3 hours of reaction.

[0074] Example 6.

[0075] (1) Weigh 100g of naphthalene, 36.5g of by-product olefin, and 1.4g of solid acid Y-type molecular sieve.

[0076] (2) The weighed naphthalene, by-product olefin and solid acid are heated to 80°C and stirred in a four-necked flask to obtain a mixture.

[0077] (3) The mixture was heated to 150°C for alkylation reaction, and samples were taken for analysis after 3 hours of reaction.

[0078] Example 7

[0079] (1) Weigh 100g of naphthalene, 36.5g of by-product olefin, and 4.1g of solid acid Y-type molecular sieve.

[0080] (2) The weighed naphthalene, by-product olefin and solid acid are heated to 80°C and stirred in a four-necked flask to obtain a mixture.

[0081] (3) The mixture was heated to 150°C for alkylation reaction, and samples were taken for analysis after 3 hours of reaction.

[0082] Example 8

[0083] (1) Weigh out 100g of naphthalene, 36.5g of by-product olefins, and 2.7g of solid acid Y-type molecular sieve.

[0084] (2) The weighed naphthalene, by-product olefin and solid acid are heated to 80°C and stirred in a four-necked flask to obtain a mixture.

[0085] (3) The mixture was heated to 150°C for alkylation reaction, and samples were taken for analysis after 1 hour of reaction.

[0086] Example 9.

[0087] (1) Weigh out 100g of naphthalene, 36.5g of by-product olefins, and 2.7g of solid acid Y-type molecular sieve.

[0088] (2) The weighed naphthalene, by-product olefin and solid acid are heated to 80°C and stirred in a four-necked flask to obtain a mixture.

[0089] (3) The mixture was heated to 150°C for alkylation reaction, and samples were taken for analysis after 2 hours of reaction.

[0090] In the above embodiments, the olefin conversion rate and selectivity of the monosubstituted product after alkylation of naphthalene and by-product olefins are shown in Table 1. The conversion rate and selectivity experimental data were obtained using an A90 gas chromatograph: injector temperature 250℃, split ratio 60:1; Agilent DB-5 column, 30m × 0.25mm × 0.25μm, constant flow mode, column flow rate 1mL / min; initial column temperature 50℃, held for 3min, increased to 70℃ at 5℃ / min and held for 5min, then increased to 250℃ at 20℃ / min and held for 35min; FID detector, temperature 250℃; injection volume 1μL. The content of the reaction product was calculated using the area normalization method, as shown below:

[0091] Olefin conversion rate:

[0092] X (conversion rate) = 100 - A (I)

[0093] In formula (Ⅰ), A is the ratio of the test concentration of the olefin after the reaction to the test concentration of the olefin before the initial reaction, multiplied by 100. In other words, the concentration of the olefin before the initial reaction is calculated by sampling and testing before the alkylation reaction, and the concentration of the olefin after the reaction is calculated by sampling and testing after the alkylation reaction.

[0094] Selectivity of alkylnaphthalenes:

[0095]

[0096] In the formula, A1 is the area percentage (%) of long-chain olefins in the initial mixed feedstock in the gas chromatogram, and A2 is the area percentage (%) of the target product long-chain alkyl naphthalene in the gas chromatogram after the reaction.

[0097] Table 1: Calculation results of alkylation reaction conversion and selectivity

[0098]

[0099] As shown in Table 1, when naphthalene reacts with olefins at a reaction temperature of 140℃~150℃ and a catalyst dosage of 1wt%~3wt% of the total weight of the reactants for 1h~3h, the olefin conversion rate is ≥86.5% and the selectivity of monosubstituted products is ≥88.0%. More optimized, the olefin conversion rate reaches as high as 99.5% and the selectivity of monosubstituted products reaches as high as 93.1%. The alkylnaphthalene preparation method of the present invention has the advantages of high reaction efficiency and high selectivity.

[0100] Example 10

[0101] (1) The reaction product of Example 9 above was subjected to vacuum distillation. Under a vacuum of 20 mmHg, the fraction at 240-260°C was collected and purified to obtain a monosubstituted product with a purity of more than 99%, which is the alkyl naphthalene prepared in this example.

[0102] (2) ExxonMobil alkyl naphthalene lubricant AN12 with the brand name Synessti TM12 was used as a control sample.

[0103] (3) Analyze and test its performance indicators: kinematic viscosity, density, viscosity index, pour point, flash point, oxidation stability. The results are shown in Table 2.

[0104] Table 2: Performance Comparison of Branched Alkyl Naphthalene and Mobil AN12 Alkyl Naphthalene Oil

[0105]

[0106]

[0107] As shown in Table 2, compared with ExxonMobil alkyl naphthalene lubricant AN12 (Synessti TM12), the alkyl naphthalene lubricant of this invention exhibits excellent oxidation stability and lower kinematic viscosity, demonstrating superior lubricating performance. This is believed to be due to the specific alkyl substituent structure of the alkyl naphthalene lubricant of this invention. Therefore, comparative testing revealed that its oxidation stability is nearly twice that of Mobil lubricant AN12, exhibiting excellent antioxidant properties.

[0108] To further analyze and characterize the alkyl naphthalene in the product, GC-MS was used for further analysis. The analytical results are as follows: Figures 1 to 11The testing instrument was a Shimadzu GC2010 gas chromatograph, and the chromatographic column was an Agilent DB-1ms, 30m×0.25mm×0.25μm. The other conditions were the same as those for the previous GC gas chromatography.

[0109] Figure 1 The total ion chromatogram of the reaction products in Example 9 exist Figure 1 In the above, peak 1 is the absorption peak of the raw material olefin; peak 2 is the absorption peak of naphthalene; peak 3 is the absorption peak of the olefin polymerization byproduct; peaks 4 and 5 are the absorption peaks of the low-carbon olefin alkylation product; and peak 6 is the absorption peak of alkylnaphthalene. Figure 1 It can be seen that the product of this application can be used to prepare branched alkyl naphthalenes. Figure 1 This is the overall gas chromatogram, followed by... Figures 2 to 13 It is the comparison result between the mass spectrum corresponding to each group of peaks and the spectrum library.

[0110] Figures 2 to 13 They are respectively: Figure 2 The mass spectrum of the reaction product at a retention time of 3.825 is shown. Figure 3 For spectral library C 10 H 20 The mass spectrum; Figure 4 The mass spectrum of the reaction product at a retention time of 6.225 is shown.

[0111] Figure 5 For C in the spectral library 10 Mass spectrum of H8; Figure 6 The mass spectrum of the reaction product at a retention time of 10.242 is shown. Figure 7 For C in the spectral library 20 H 42 Mass spectrum of O; Figure 8 The mass spectrum of the reaction product at a retention time of 11.100; Figure 9 For the score C in the gallery 14 H 16 The mass spectrum; Figure 10 The mass spectrum of the reaction product at a retention time of 11.400 is shown. Figure 11 For the spectral library C 14 H 16 The mass spectrum; Figure 12 The mass spectrum of the reaction product at a retention time of 12.058 is shown. Figure 13 For C in the spectral library 20 H 28 The mass spectrum.

[0112] In this application, the olefins are derived from olefin oligomerization byproducts. These olefins contain various branched structures and a certain proportion of non-terminal olefins. Therefore, the alkyl naphthalenes generated by the alkylation reaction have significantly different substituent structures compared to existing studies, where the substituents are primarily long-chain structures. Compared to the synthesis of alkylphenol naphthalenes disclosed in existing patents, this method uses byproduct olefins as raw materials to synthesize alkyl naphthalenes, resulting in a significantly different substituent structure. Furthermore, testing has revealed that it possesses excellent antioxidant properties. This invention provides a method for preparing an alkyl naphthalene lubricating oil with excellent antioxidant properties. This method uses byproduct olefins and naphthalene as raw materials, employs a solid acid catalyst, achieves high olefin conversion, high selectivity for monosubstituted alkyl naphthalenes, mild reaction conditions, and simple equipment operation. The preparation method for monosubstituted alkyl naphthalenes in this invention is as follows: the reaction is carried out intermittently. Naphthalene, byproduct olefins, and catalyst are weighed into a flask, the naphthalene is melted by heating, stirring is started, and the temperature is raised to a specified level. After the reaction is complete, a sample is dissolved and diluted with dichloromethane, and the composition is analyzed by gas chromatography. The catalyst is a Y-type molecular sieve with a silicon-to-aluminum ratio of 15:1, and the catalyst dosage is 1% to 3% of the total weight of the reactants. The by-product olefin is a by-product of the olefin polymerization unit, and its main component is decene with a content ≥98%. The molar ratio of the olefin to naphthalene is 2:1 to 4:1. The reaction temperature is 140℃ to 160℃. The reaction time is 1 to 3 hours. The advancement of this invention lies in providing a method for preparing an alkylnaphthalene lubricating oil with excellent antioxidant properties. In a preferred embodiment, the olefin conversion rate can reach 99.4%, the selectivity of the monosubstituted product is 93.1%, and the reaction efficiency, activity, and selectivity are high. The raw material used is a by-product olefin containing various branched structures and a certain proportion of non-terminal olefins. Therefore, the alkylnaphthalene product has a different substituent structure from existing studies. Through comparative testing, its oxidation stability is found to be twice that of Mobil lubricating oil AN12, exhibiting excellent antioxidant properties. Due to the difference in substituent structure, the alkylnaphthalene prepared in this invention exhibits excellent oxidation stability and low kinematic viscosity.

[0113] The above detailed description is merely a preferred embodiment of the present invention, and the scope of protection of the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, including combining 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 all fall within the scope of protection of the present invention.

Claims

1. A process for the preparation of alkyl naphthalenes, characterized in that, The alkyl naphthalene is prepared by alkylation of naphthalene and branched decene in the presence of an acidic catalyst.

2. The production method according to claim 1, characterized by, The branched decene is replaced by a by-product olefin, wherein the by-product olefin is an ethylene oligomerization by-product olefin in a process for producing 1-hexene; and the by-product olefin comprises at least one branched decene.

3. The production method according to claim 2, characterized by, The preparation method comprises: (1) mixing naphthalene, the by-product olefin and the acidic catalyst to obtain a mixture; and (2) subjecting the mixture to alkylation at a temperature of 140-160°C. Optionally, the acidic catalyst is a solid acidic catalyst. Optionally, (3) subjecting the reaction product of step (2) to vacuum distillation, preferably under the conditions of a vacuum degree of 10-30 mmHg and collecting a fraction at 240-260°C.

4. The production method according to claim 3, characterized by, The alkyl naphthalene is a mono-substituted alkyl naphthalene. Optionally, the mixing in step (1) is carried out at a temperature of 70-90°C. Optionally, the alkylation in step (2) is carried out for 1-3 hours.

5. The method of any one of claim 4, wherein, The solid acidic catalyst is a Y-type molecular sieve with a silica-alumina ratio of 10:1-20:1, preferably 15:1-16:1; and / or the catalyst is used in an amount of 1-3 wt% based on the total mass of the by-product olefin and naphthalene.

6. The production method according to any one of claims 2 to 5, characterized by, The amount of the branched decene is ≥98% based on the total mass of the by-product olefin. Optionally, the molar ratio of the by-product olefin to the naphthalene is 2:1-4:

1.

7. The production method according to any one of claims 1 to 6, characterized by, The branched decene is selected from at least one of compounds of formula (1), formula (2), formula (3), formula (4) and formula (5). In formula (1), R1 and R2 are each independently selected from C1-C6 alkyl groups, and the total number of carbon atoms in R1 and R2 is 7; in formula (2), R3 and R4 are each independently selected from C1-C5 alkyl groups, and the total number of carbon atoms in R3 and R4 is 6; in formula (3), R5 is a C4 alkyl group; in formula (4), R6 is a C4 alkyl group; and in formula (5), R7 and R8 are each independently selected from C1-C7 alkyl groups, and the total number of carbon atoms in R7 and R8 is 8.

8. The method of any one of claim 7, wherein, The branched decene comprises 20-30% of the compound of formula (1), 0-10% of the compound of formula (2), 10-20% of the compound of formula (3), 35-45% of the compound of formula (4) and 0-10% of the compound of formula (5) in terms of molar content. Preferably, the branched decene comprises 25-26% of the compound of formula (1), 6-7% of the compound of formula (2), 18-19% of the compound of formula (3), 39-40% of the compound of formula (4) and 4-5% of the compound of formula (5).

9. The alkyl naphthalene or alkyl naphthalene lubricating oil prepared by the preparation method of any one of claims 1-8.

10. Use of the alkyl naphthalene or alkyl naphthalene lubricating oil of claim 9 in hydraulic oil, gear oil, heat transfer oil, transformer oil, refrigerator oil, compressor oil, and the field of liquid crystal.

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