Method for removing 2, 5-diphenyl oxazole in linear alkylbenzene and application

Abstract

The invention discloses a method for removing 2, 5-diphenyloxazole in linear alkylbenzene and application thereof.The linear alkylbenzene containing 2, 5-diphenyloxazole is subjected to shallow sulfonation in the presence of catalysts such as a 4A molecular sieve, activated carbon, kaolin and bentonite at the temperature of 0-30 DEG C, the content of 2, 5-diphenyloxazole in the linear alkylbenzene can be reduced to 6 ppm or below from 3000 ppm through simple filtration, and the 2, 5-diphenyloxazole in the linear alkylbenzene can be reduced to 6 ppm or below. And sulfonating through an SO3 membrane reactor to obtain an alkyl benzene sulfonic acid superior product.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of surfactants, and particularly relates to a method for removing 2,5-diphenyl oxazole in linear alkylbenzene and application. BACKGROUND

[0002] Liquid scintillator is the core device of neutrino detector, which is the target material for capturing neutrinos. The liquid scintillator used in Jiangmen neutrino experiment uses high-purity linear alkylbenzene as a solvent and 2,5-diphenyl oxazole as a luminescent substance. The linear alkylbenzene used reaches 20,000 tons. With the continuous development of neutrino experiments, the liquid scintillator needs to be continuously updated to ensure high-quality output of signals. Therefore, the amount of alkylbenzene waste produced is increasing.

[0003] Alkylbenzene is an important raw material for preparing anionic surfactant alkylbenzene sulfonate, and the market demand at home and abroad is huge. However, although 99.7% of the liquid scintillator is linear alkylbenzene, the presence of 0.3% of the scintillator 2,5-diphenyl oxazole seriously affects the normal operation of the sulfonation reaction device of alkylbenzene, and affects the application of alkylbenzene sulfonate. It is urgent to convert the alkylbenzene waste produced by neutrino experiments into high-value fine chemicals.

[0004] Therefore, there is an urgent need in the art for a method for effectively removing 2,5-diphenyl oxazole from the alkylbenzene waste discarded by neutrino experiments. SUMMARY

[0005] This section aims to summarize some aspects of the embodiments of the application and briefly introduce some preferred embodiments.

[0006] In view of the above and / or problems existing in the prior art, the present application is proposed.

[0007] Therefore, the purpose of the present application is to overcome the deficiencies in the prior art, and to provide a method for removing 2,5-diphenyl oxazole in linear alkylbenzene.

[0008] To solve the above technical problems, the present application provides the following technical scheme: a method for removing 2,5-diphenyl oxazole in linear alkylbenzene, comprising, mixing linear alkylbenzene containing 2,5-diphenyl oxazole with a catalyst at low temperature, and then adding a sulfonating agent dropwise for sulfonation reaction; After the reaction is completed, stand still, and remove the precipitate by filtration.

[0009] As a preferred scheme of the method, the catalyst is one of 4A molecular sieve, activated carbon, kaolin, bentonite and hydroxyapatite.

[0010] In a preferred embodiment of the method described in this invention, the catalyst accounts for 0.5 to 5% of the mass of the linear alkylbenzene containing 2,5-diphenyloxazole.

[0011] In a preferred embodiment of the method described in this invention, the sulfonating agent is one of chlorosulfonic acid, concentrated sulfuric acid, and fuming sulfuric acid.

[0012] In a preferred embodiment of the method described in this invention, the sulfonating agent accounts for 0.5 to 10% of the mass of the linear alkylbenzene containing 2,5-diphenyloxazole.

[0013] In a preferred embodiment of the method described in this invention, the sulfonation reaction temperature is 0~30℃.

[0014] In a preferred embodiment of the method described in this invention, the sulfonation reaction time is 10-120 minutes.

[0015] In a preferred embodiment of the method described in this invention, the settling time is 0.5 to 12 hours.

[0016] In a preferred embodiment of the method described in this invention, the content of 2,5-diphenyloxazole in the linear alkylbenzene containing 2,5-diphenyloxazole is 3000 ppm, which is reduced to below 6 ppm after treatment.

[0017] Another object of the present invention is to overcome the shortcomings of the prior art and provide a method for removing 2,5-diphenyloxazole from linear alkylbenzenes.

[0018] Application of one method of the method described in this invention in the purification of alkylbenzene.

[0019] Beneficial effects of this invention: (1) This invention proposes for the first time a method for removing 2,5-diphenyloxazole from linear alkylbenzene. The required reagents are inexpensive and readily available, the equipment is simple and easy to operate, and it is feasible for industrial scale-up. After treatment by the technical solution provided by this invention, the content of 2,5-diphenyloxazole in alkylbenzene can be reduced to less than 6.0 ppm and become transparent and colorless.

[0020] (2) Alkylbenzene treated by the technical solution provided by the present invention can be successfully filmed on an SO3 mode reactor without the generation of coking particles. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein: Figure 1 The infrared spectrum is that of the alkylbenzene prepared in Example 1.

[0022] Figure 2 The image shows the coking phenomenon of the alkylbenzene prepared in Example 5 in an SO3 membrane reactor. Detailed Implementation

[0023] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0024] The method for preparing 0.3% 2,5-diphenyloxazole linear alkylbenzene in this invention is as follows: accurately weigh 3 grams of 2,5-diphenyloxazole and add it to 997 grams of linear alkylbenzene, then stir and mix evenly. In the embodiments of this invention, 4A molecular sieve, kaolin, activated carbon, and bentonite were all purchased from Aladdin Reagent Company and are all commercially available products.

[0025] Example 1 This embodiment provides a method for removing 2,5-diphenyloxazole from linear alkylbenzenes. The main steps are as follows: (1) Weigh 100g of linear alkylbenzene containing 0.3% 2,5-diphenyloxazole and 0.5g of 4A molecular sieve into a four-necked flask and cool it to 5℃ in an ice-water bath; (2) After adding 0.5 g of chlorosulfonic acid, continue stirring for 10 minutes; (3) Filter after standing at room temperature for 0.5 hours.

[0026] (4) The content of 2,5-diphenyloxazole in the filtrate was determined to be 3.2 ppm by ultraviolet-visible spectrophotometry.

[0027] The infrared spectrum of the prepared alkylbenzene is shown in [reference]. Figure 1 Infrared spectroscopy characterization confirmed the presence of linear alkylbenzenes.

[0028] Example 2 This embodiment provides a method for removing 2,5-diphenyloxazole from linear alkylbenzenes. The main steps are as follows: (1) Weigh 100g of linear alkylbenzene containing 0.3% 2,5-diphenyloxazole and 3g of kaolin into a four-necked flask and cool it to 10°C in an ice-water bath; (2) Add 1 gram of concentrated sulfuric acid (98%) and continue stirring for 20 minutes; (3) Filter after standing at room temperature for 2 hours.

[0029] (4) The content of 2,5-diphenyloxazole in the filtrate was determined to be 4.1 ppm by ultraviolet-visible spectrophotometry.

[0030] Example 3 This embodiment provides a method for removing 2,5-diphenyloxazole from linear alkylbenzenes. The main steps are as follows: (1) Weigh 100g of linear alkylbenzene containing 0.3% 2,5-diphenyloxazole and 1g of activated carbon into a four-necked flask and cool it to 30°C in an ice-water bath; (2) After adding 3 grams of fuming sulfuric acid, continue stirring for 60 minutes; (3) Filter after standing at room temperature for 6 hours.

[0031] (4) The content of 2,5-diphenyloxazole in the filtrate was determined to be 4.9 ppm by ultraviolet-visible spectrophotometry.

[0032] Example 4 This embodiment provides a method for removing 2,5-diphenyloxazole from linear alkylbenzenes. The main steps are as follows: (1) Weigh 100g of linear alkylbenzene containing 0.3% 2,5-diphenyloxazole and 5g of bentonite into a four-necked flask and cool it to 20°C in an ice-water bath; (2) After adding 2.5 g of chlorosulfonic acid, continue stirring for 90 minutes; (3) Filter after standing at room temperature for 9 hours.

[0033] (4) The content of 2,5-diphenyloxazole in the filtrate was determined to be 5.7 ppm by ultraviolet-visible spectrophotometry.

[0034] Example 5 This embodiment provides a method for removing 2,5-diphenyloxazole from linear alkylbenzenes. The main steps are as follows: (1) Weigh 100 grams of linear alkylbenzene containing 0.3% 2,5-diphenyloxazole into a four-necked flask and cool it to 5°C in an ice-water bath; (2) After adding 1 gram of chlorosulfonic acid, continue stirring for 10 minutes; (3) Filter after standing at room temperature for 0.5 hours.

[0035] (4) The content of 2,5-diphenyloxazole in the filtrate was determined to be 460 ppm by ultraviolet-visible spectrophotometry.

[0036] Example 6 This embodiment provides a method for removing 2,5-diphenyloxazole from linear alkylbenzenes. The main steps are as follows: (1) Weigh 100g of linear alkylbenzene containing 0.3% 2,5-diphenyloxazole and 1g of 4A molecular sieve into a four-necked flask and cool it to 5°C in an ice-water bath; (2) Continue stirring and reacting for 10 minutes; (3) Filter after standing at room temperature for 0.5 hours.

[0037] (4) The content of 2,5-diphenyloxazole in the filtrate was determined to be 2700 ppm by ultraviolet-visible spectrophotometry.

[0038] Analysis of the 2,5-diphenyloxazole content in linear alkylbenzenes after different process treatments in this invention embodiment: Using pure 2,5-diphenyloxazole as a standard, a standard curve was established by UV-Vis spectrophotometry. Then, the alkylbenzenes treated in Examples 1 to 6 were measured respectively, and the results are shown in Table 1.

[0039] The standard curve was established as follows: a certain amount of 2,5-diphenyloxazole standard was accurately weighed, dissolved in n-decane, and then diluted to 100 mL; a series of 2,5-diphenyloxazole standard solutions of different concentrations were obtained by gradient dilution; after equilibration at 25 °C for 24 hours, the UV absorbance of each sample was measured in the range of 200–500 nm; the maximum absorbance of the sample in the wavelength range of 290–305 nm was plotted against the concentration of 2,5-diphenyloxazole standard to obtain the linear fitting equation: y = 0.4854x + 0.0106 (R² = 0.9998).

[0040] Analysis of SO3 membrane reaction coking of linear alkylbenzenes after different process treatments in this invention: The alkylbenzenes treated in Examples 1 to 6 were subjected to sulfonation reactions in an indoor SO3 membrane reactor. The coking situation in the reactor was observed, and the content and color of the produced alkylbenzene sulfonic acid were determined and analyzed in accordance with GB / T8447-2008.

[0041] The process conditions for SO3 membrane sulfonation are as follows: the molar ratio of SO3 to alkylbenzene is 1.1:1, the SO3 gas concentration is 7%, and the sulfonator cooling jacket temperature is 60℃.

[0042] The results are shown in Table 1.

[0043] Table 1

[0044] As can be seen from Table 1, after treatment with the method for removing 2,5-diphenyloxazole from linear alkylbenzenes proposed in this invention, the content of 2,5-diphenyloxazole in linear alkylbenzenes can be reduced from the initial 3000 ppm to below 6 ppm, or even to 3.2 ppm.

[0045] As a comparative example, without a catalyst, the 2,5-diphenyloxazole content in linear alkylbenzenes could only be reduced to 460 ppm; while without sulfonation treatment, the 2,5-diphenyloxazole content in linear alkylbenzenes could only be reduced to 2700 ppm. That is, the catalyst and sulfonating agent have a significant synergistic effect when treating 2,5-diphenyloxazole in linear alkylbenzenes.

[0046] By performing SO3 membrane sulfonation on the alkylbenzenes treated in Examples 1-6, it was found that after treatment with the method proposed in this invention for removing 2,5-diphenyloxazole from linear alkylbenzenes, the alkylbenzenes did not coke in the SO3 membrane sulfonation reactor, and the liquid film was uniform and smooth. The obtained alkylbenzene sulfonic acid content was as high as 98.6% or more, and the color was relatively small, reaching the superior grade specified in GB / T8447-2008.

[0047] In contrast, the alkylbenzenes treated in Example 5 (without catalyst) and Example 6 (without sulfonating agent) both exhibited coking during the sulfonation reaction in the SO3 membrane reactor. In particular, the alkylbenzenes treated in Example 6 caused excessive coking particles, leading to reactor blockage and preventing the formation of a liquid film, thus making the sulfonation reaction impossible.

[0048] The coking phenomenon of the alkylbenzene prepared in Example 5 in the SO3 membrane reactor is described in [reference needed]. Figure 2 Although the sulfonation reaction was barely completed in Example 5, the uneven film formation resulted in a low content of alkylbenzene sulfonic acid in the product and a dark color, which could not meet the level specified in GB / T8447-2008.

[0049] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the present invention.

Claims

1. A method for removing 2,5-diphenyloxazole from linear alkylbenzenes, characterized in that: include, A linear alkylbenzene containing 2,5-diphenyloxazole was mixed with a catalyst at low temperature, and then a sulfonating agent was added dropwise to carry out a sulfonation reaction. After the reaction is complete, let it stand and then filter to remove the precipitate.

2. The method as described in claim 1, characterized in that: The catalyst is one of 4A molecular sieve, activated carbon, kaolin, bentonite, and hydroxyapatite.

3. The method as described in claim 1 or 2, characterized in that: The catalyst accounts for 0.5 to 5% of the mass of the linear alkylbenzene containing 2,5-diphenyloxazole.

4. The method as described in claim 3, characterized in that: The sulfonating agent is one of chlorosulfonic acid, concentrated sulfuric acid, or fuming sulfuric acid.

5. The method as described in claim 1 or 4, characterized in that: The sulfonating agent accounts for 0.5 to 10% of the mass of the linear alkylbenzene containing 2,5-diphenyloxazole.

6. The method as described in claim 1, characterized in that: The sulfonation reaction is carried out at a temperature of 0~30℃.

7. The method as described in claim 1 or 6, characterized in that: The sulfonation reaction takes 10 to 120 minutes.

8. The method as described in claim 1, characterized in that: The settling time is 0.5 to 12 hours.

9. The method according to any one of claims 1, 2, 4, 6, and 8, characterized in that: The linear alkylbenzene containing 2,5-diphenyloxazole had a 2,5-diphenyloxazole content of 3000 ppm, which was reduced to below 6 ppm after treatment.

10. The use of the method according to any one of claims 1 to 9 in the purification of alkylbenzene.

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