Preparation method of decabromodiphenyl ethane

Abstract

The invention discloses a preparation method of decabromodiphenylethane, and relates to the technical field of chemical production, and the preparation method comprises the following steps: feeding bromine and a composite catalyst into a reaction kettle, and after stirring is completed, adding diphenylethane in a molten state into the reaction kettle; adding a saturated sodium sulfite solution, adjusting the pH value, heating to 90-100 DEG C, and recovering evaporated bromine to prepare a pretreated material; cooling the pretreated material to 15-30 DEG C, then washing, and carrying out solid-liquid separation to obtain a crude product; and grinding the crude product material, washing, drying, and carrying out jet milling to obtain the high-whiteness decabromodiphenylethane. Therefore, the kaolin is modified by adopting the hexadecyl trimethyl ammonium bromide-ethanol solution, and the 1, 3-bis (diphenylphosphino propane) nickel dichloride is introduced, so that the composite catalyst can generate relatively strong adsorption and activation effects on bromine molecules and diphenylethane; the catalyst has more reaction paths and selectivity in catalysis of bromine and diphenylethane reaction.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical production, and particularly relates to a preparation method of decabromodiphenylethane. Background Art

[0002] Decabromodiphenylethane is a new type, broad-spectrum, highly efficient, and environmentally friendly additive flame retardant developed and produced in recent years. Its heat resistance, light resistance, and non-permeability properties are superior to those of decabromodiphenyl ether. Moreover, their flame retardancy is basically the same, but decabromodiphenylethane does not produce the polybrominated dibenzo-p-dioxins that people are worried about during flame retardancy, and its toxicity is lower than that of decabromodiphenyl ether.

[0003] Chinese Patent with the publication number "CN114213210B" discloses "a preparation method of decabromodiphenylethane", and its disclosure content is "a supported composite catalyst is added in the bromination stage. The supported composite catalyst uses cationic surfactant-modified montmorillonite as the carrier to support the composite catalyst, and the composite catalyst is a mixture of iron salt and / or aluminum salt, antimony salt, and organic nickel complex. By using modified montmorillonite as the carrier and loading multiple metal active components as the composite catalyst, the obtained decabromodiphenylethane has high whiteness, good thermal stability, and high yield, and is a preparation process suitable for industrial production of high-quality decabromodiphenylethane".

[0004] In the above scheme, montmorillonite is used as the carrier to load multiple metal components as the composite catalyst. However, montmorillonite is a 2:1 type layered silicate (silicon-oxygen tetrahedron sandwiching aluminum-oxygen octahedron), and the layers are only combined by van der Waals forces, which is easy to absorb water and expand or even collapse in structure. Moreover, this structure makes montmorillonite extremely prone to structural collapse in an environment above 400 °C, which leads to extremely unstable high-temperature catalytic reactions and affects the final product. Summary of the Invention

[0005] Aiming at the above defects, the purpose of the present invention is to provide a preparation method of decabromodiphenylethane, aiming to solve the problem of instability of the catalyst in the high-temperature environment during the production process of decabromodiphenylethane in the prior art.

[0006] To solve the above technical problems, the technical solution of the present invention is as follows: A preparation method of decabromodiphenylethane includes the following steps: Step 1: Feed bromine and the composite catalyst into the reaction kettle, stir and mix, adjust the temperature in the reaction kettle to 15 - 30 °C, the pressure to -20 - 10 KPa, and the stirring time to 20 - 30 min; after stirring is completed, add molten diphenylethane into the reaction kettle, and continue to stir for 2 - 4 h; Step 2: Raise the temperature of the reaction kettle in Step 1 to 40 - 50 °C, the pressure to -5 - 10 KPa, and the reaction time to 3 - 5 h; Step 3: Heat the reactor in Step 2 to 55 - 60°C, with a pressure of -5 - 10 KPa and a reaction time of 4 - 6 h to obtain a reaction solution. Step 4: First, filter the reaction solution to recover the composite catalyst; then add deionized water to the reaction solution, with the mass ratio of the reaction solution to deionized water being 1:0.9 - 1.2. Heat the reactor to 80 - 90°C to recover the evaporated bromine; then add a saturated sodium sulfite solution to adjust the pH value to 6.5 - 7.5 and cool to 60 - 70°C to obtain a pretreated material. Step 5: Cool the pretreated material to 15 - 30°C, then wash and perform solid - liquid separation to obtain a crude product; grind, wash, dry the crude product material, and perform air - flow pulverization to obtain high - whiteness decabromodiphenylethane.

[0007] Among them, the composite catalyst includes a carrier particle and a pre - catalyst. The carrier particle is a modified kaolin powder, and the pre - catalyst is ferric nitrate and aluminum chloride.

[0008] Among them, the preparation method of the composite catalyst is as follows: S1: Select hard kaolin with a kaolin content ≥ 95% and crush it to 200 - 400 meshes. Then send the hard kaolin to a high - temperature kiln for high - temperature roasting for 5 - 6 h to obtain decarboxylated activated kaolin. S2: Take a cetyltrimethylammonium bromide - ethanol solution with a mass concentration of 3 - 5%. Mix it with the decarboxylated activated kaolin in a mixing kettle at a solid - liquid ratio of 1:(3 - 5). Then perform ultrasonic treatment at a frequency of 30 - 40 kHz for 20 - 30 min. Then heat the mixing kettle to 120 - 140°C, adjust the pressure in the kettle to 0.6 - 0.8 MPa, and the reaction time is 1 - 3 h to obtain a carrier liquid. S3: Dissolve ferric nitrate and aluminum chloride in an ethanol solution with an alcohol concentration of 60% at a molar ratio of 1:1, add 1,3 - bis(diphenylphosphinopropane)dichloronickel, and adjust the pH value to 4.5 ± 0.2 to obtain an impregnation solution. S4: Mix the carrier liquid and the impregnation solution at a mass ratio of (1 - 1.5):(1 - 2), then perform centrifugal drying to obtain the composite catalyst.

[0009] Among them, in Step 1, the mass ratio of the composite catalyst to diphenylethane is 2.5 - 4:1.

[0010] Among them, in Step 1, the mass ratio of bromine to diphenylethane is 15 - 24:1.

[0011] Among them, in S1, the specific surface area of the decarboxylated activated kaolin ≥ 300 m 2 / g, and the thermal stability ≥ 1000°C.

[0012] Among them, in S3, according to the mass ratio, the mass ratio of the dosage of bis(diphenylphosphinopropane)nickel dichloride to the mass of the decarboxylated activated kaolin dry matrix is (0.3~0.6):1.

[0013] Among them, in S4, after the carrier liquid and the impregnation liquid are mixed, ultrasonic treatment is also required for 30~40 min, and the ultrasonic treatment frequency is 50~60 kHz.

[0014] Among them, in S4, after ultrasonic treatment, the mixed liquid needs to be left standing for aging for 10~15 h.

[0015] Among them, in S4, the powder particles obtained after centrifugal drying need to be further calcined in an autoclave at 300~400 °C for 2~4 h to obtain the composite catalyst.

[0016] After adopting the above technical solution, the beneficial effects of the present invention are as follows: By modifying kaolin with cetyltrimethylammonium bromide-ethanol solution and introducing bis(diphenylphosphinopropane)nickel dichloride, the composite catalyst can have a strong adsorption and activation effect on bromine molecules and diphenylethane, and has more reaction paths and selectivities in the catalytic reaction of bromine and diphenylethane. It can also form a specific complex with the reaction intermediate, stabilize the transition state in the reaction process, guide the reaction to proceed in a specific direction, improve the selectivity of the reaction, and make the produced decabromodiphenylethane have a higher purity and fewer by-products. Specific embodiments

[0017] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0018] A method for preparing decabromodiphenylethane includes the following steps: Step 1: Feed bromine and the composite catalyst into a reaction kettle, stir and mix, adjust the temperature in the reaction kettle to 15~30 °C, the pressure to -20~10 KPa, and the stirring time to 20~30 min; after stirring is completed, add molten diphenylethane into the reaction kettle and continue stirring for 2~4 h; Step 2: Raise the temperature of the reaction kettle in Step 1 to 40~50 °C, the pressure to -5~10 KPa, and the reaction time to 3~5 h; Step 3: Raise the temperature of the reaction kettle in Step 2 to 55~60 °C, the pressure to -5~10 KPa, and the reaction time to 4~6 h to obtain the reaction solution; Step 4: First, filter the reaction solution to recover the composite catalyst; then add deionized water to the reaction solution, with the mass ratio of the reaction solution to deionized water being 1:0.9 - 1.2. Heat the reaction kettle to 80 - 90 °C to recover the evaporated bromine; then add a saturated sodium sulfite solution, adjust the pH value to 6.5 - 7.5, and cool down to 60 - 70 °C to obtain the pretreated material. Step 5: Cool the pretreated material to 15 - 30 °C, then wash and perform solid-liquid separation to obtain the crude product; grind, wash, dry the crude product material, and perform air-flow pulverization to obtain high-whiteness decabromodiphenylethane.

[0019] The composite catalyst includes a carrier particle and a pre-catalyst. The carrier particle is a modified kaolin powder, and the pre-catalyst is a metal salt.

[0020] The preparation method of the composite catalyst is as follows: S1: Select hard kaolin with a kaolin content ≥ 95% and crush it to 200 - 400 mesh. Then send the hard kaolin to a high-temperature kiln for high-temperature roasting for 5 - 6 h to obtain decarboxylated activated kaolin. S2: Take a cetyltrimethylammonium bromide-ethanol solution with a mass concentration of 3 - 5%. Mix it with the decarboxylated activated kaolin in a mixing kettle at a solid-liquid ratio of 1:(3 - 5). Then perform ultrasonic treatment at a frequency of 30 - 40 kHz for 20 - 30 min. Then heat the mixing kettle to 120 - 140 °C, adjust the pressure in the kettle to 0.6 - 0.8 MPa, and the reaction time is 1 - 3 h to obtain the carrier liquid. S3: Dissolve ferric nitrate and aluminum chloride in an ethanol solution with an alcohol concentration of 60% at a molar ratio of 1:1. Add 1,3-bis(diphenylphosphinopropane)dichloronickel and adjust the pH value to 4.5 ± 0.2 to obtain the impregnation liquid. S4: Mix the carrier liquid and the impregnation liquid at a mass ratio of (1 - 1.5):(1 - 2), then perform centrifugal drying to obtain the composite catalyst.

[0021] In Step 1, the mass ratio of the composite catalyst to diphenylethane is 2.5 - 4:1.

[0022] In Step 1, the mass ratio of bromine to diphenylethane is 15 - 24:1.

[0023] In S1, the specific surface area of the decarboxylated activated kaolin ≥ 300 m 2 / g, and the thermal stability ≥ 1000 °C.

[0024] In S3, by mass ratio, the dosage of 1,3-bis(diphenylphosphinopropane)dichloronickel to the dry matrix mass of the decarboxylated activated kaolin is (0.3 - 0.6):1.

[0025] In S4, after the carrier liquid and the impregnation liquid are mixed, ultrasonic treatment for 30 - 40 min is required, and the ultrasonic treatment frequency is 50 - 60 kHz.

[0026] In S4, after the ultrasonic treatment, the mixed liquid needs to be left standing for aging for 10 - 15 h.

[0027] In S4, after centrifugal drying is completed, the powder particles obtained need to be further calcined in an autoclave at 300 - 400 °C for 2 - 4 h to obtain the composite catalyst.

[0028] Example 1: Using the above - mentioned scheme to prepare decabromodiphenylethane, where: Step 1: Feed bromine and the composite catalyst into the reaction kettle, stir and mix, adjust the temperature in the reaction kettle to 15 °C, the pressure to - 20 KPa, and the stirring time to 20 min; after stirring is completed, add molten diphenylethane into the reaction kettle and continue stirring for 2 h; Step 2: Heat the reaction kettle in Step 1 to 40 °C, the pressure to - 5 KPa, and the reaction time to 3 h; Step 3: Heat the reaction kettle in Step 2 to 55 °C, the pressure to - 5 KMPa, and the reaction time to 4 h; Step 4: First, filter the reaction solution to recover the composite catalyst; then add deionized water to the reaction solution, the mass ratio of the reaction solution to deionized water is 1:0.9, heat the reaction kettle to 80 °C to recover the evaporated bromine; then add saturated sodium sulfite solution, adjust the pH value to 6.5, and cool down to 60 °C to obtain the pretreated material; The preparation method of the composite catalyst is as follows: S1: Select hard kaolin with a kaolin content ≥ 95% and crush it to 200 meshes, then send the hard kaolin to a high - temperature kiln for high - temperature roasting for 5 h to obtain decarboxylated activated kaolin; S2: Take a 3% cetyltrimethylammonium bromide - ethanol solution, mix it with the decarboxylated activated kaolin in a mixing kettle at a solid - liquid ratio of 1:3, then perform ultrasonic treatment at a frequency of 30 kHz for 20 min, then heat the mixing kettle to 120 °C, adjust the pressure in the kettle to 0.6 MPa, and the reaction time is 1 h to obtain the carrier liquid; S3: Dissolve ferric nitrate and aluminum chloride in an ethanol solution with an alcohol concentration of 60% at a molar ratio of 1:1, add 1,3 - bis(diphenylphosphinopropane)dichloronickel, and adjust the pH value to 4.7 to obtain the impregnation liquid; S4: Mix the carrier liquid and the impregnation liquid at a mass ratio of 1:1, then perform centrifugal drying to obtain the composite catalyst.

[0029] In Step 1, the mass ratio of the composite catalyst to diphenylethane is 2.5:1.

[0030] In Step 1, the mass ratio of bromine to diphenylethane is 15:1.

[0031] In S3, by mass ratio, the dosage of 1,3-bis(diphenylphosphinopropane) dichloronickel to the mass of the decarboxylated activated kaolin dry matrix is 0.3:1.

[0032] In S4, after the carrier liquid and the impregnation liquid are mixed, ultrasonic treatment is required for 30 min, and the ultrasonic treatment frequency is 50 kHz.

[0033] In S4, after ultrasonic treatment, the mixed liquid needs to be left standing for aging for 10 h.

[0034] In S4, after centrifugal drying is completed, the obtained powder particles need to be further calcined in an autoclave at 300 °C for 2 h to obtain the composite catalyst.

[0035] Example 2: The difference between this example and Example 1 is as follows: Step 1: Feed bromine and the composite catalyst into the reaction kettle, stir and mix, adjust the temperature in the reaction kettle to 17 °C, the pressure to -10 KPa, and the stirring time to 25 min; after stirring is completed, add molten diphenylethane into the reaction kettle and continue stirring for 3 h; Step 2: Heat the reaction kettle in Step 1 to 45 °C, the pressure to -4 KPa, and the reaction time to 4 h; Step 3: Heat the reaction kettle in Step 2 to 57 °C, the pressure to -4 KPa, and the reaction time to 4.5 h; Step 4: First, filter the reaction solution to recover the composite catalyst; then add deionized water to the reaction solution, the mass ratio of the reaction solution to deionized water is 1:1, heat the reaction kettle to 85 °C to recover the evaporated bromine; then add saturated sodium sulfite solution to adjust the pH value to 7, and cool down to 65 °C to obtain the pretreated material; The preparation method of the composite catalyst is as follows: S1: Select hard kaolin with a kaolin content of ≥95% and crush it to 250 mesh, then send the hard kaolin to a high-temperature kiln for high-temperature calcination for 5.5 h to obtain decarboxylated activated kaolin; S2: Take a 3.5% cetyltrimethylammonium bromide-ethanol solution, mix it with the decarboxylated activated kaolin in a mixing kettle at a solid-liquid ratio of 1:4, then perform ultrasonic treatment at a frequency of 35 kHz for 25 min, then heat the mixing kettle to 130 °C, adjust the pressure in the kettle to 0.65 MPa, and the reaction time is 1.5 h to obtain the carrier liquid; S3. Dissolve ferric nitrate and aluminum chloride in an ethanol solution with an alcohol concentration of 60% at a molar ratio of 1:1, add 1,3-bis(diphenylphosphinopropane)dichloronickel, and adjust the pH value to 4.4 to obtain an impregnation solution. S4. Mix the carrier solution and the impregnation solution at a mass ratio of 1.5:2, and then centrifuge and dry to obtain a composite catalyst.

[0036] In Step 1, the mass ratio of the composite catalyst to diphenylethane is 3:1.

[0037] In Step 1, the mass ratio of bromine to diphenylethane is 17:1.

[0038] In S3, by mass ratio, the dosage of 1,3-bis(diphenylphosphinopropane)dichloronickel to the mass of the decarboxylated activated kaolin dry matrix is 0.5:1.

[0039] In S4, after mixing the carrier solution and the impregnation solution, ultrasonic treatment is required for 35 min at an ultrasonic treatment frequency of 55 kHz.

[0040] In S4, after ultrasonic treatment, the mixed solution needs to be left standing for aging for 12 h.

[0041] In S4, after centrifugal drying, the obtained powder particles need to be further calcined in an autoclave at 350 °C for 3 h to obtain a composite catalyst.

[0042] Example 3: The difference between this example and Example 1 is as follows: Step 1. Feed bromine and the composite catalyst into the reaction kettle, stir and mix, adjust the temperature in the reaction kettle to 20 °C, the pressure to 5 KPa, and the stirring time to 27 min; after stirring is completed, add molten diphenylethane into the reaction kettle and continue stirring for 3.5 h; Step 2. Heat the reaction kettle in Step 1 to 47 °C, the pressure to 2 KPa, and the reaction time to 4.5 h; Step 3. Heat the reaction kettle in Step 2 to 58 °C, the pressure to 2 KPa, and the reaction time to 5 h; Step 4. First, filter the reaction solution to recover the composite catalyst; then add deionized water to the reaction solution, the mass ratio of the reaction solution to deionized water is 1:1.1, heat the reaction kettle to 87 °C to recover the evaporated bromine; then add a saturated sodium sulfite solution, adjust the pH value to 27, and cool down to 67 °C to obtain a pretreated material. The preparation method of the composite catalyst is as follows: S1. Select hard kaolin with a kaolin content of ≥95% and crush it to 350 mesh, and then send the hard kaolin to a high-temperature kiln for high-temperature calcination for 5.7 h to obtain decarboxylated activated kaolin. S2. Take a cetyltrimethylammonium bromide - ethanol solution with a mass concentration of 4.2%, mix it with decarboxylated activated kaolin in a mixing kettle at a solid - liquid ratio of 1:4.5, then perform ultrasonic treatment at a frequency of 37 kHz for 27 min. Then, heat the mixing kettle to 135 °C, adjust the pressure in the kettle to 0.7 MPa, and react for 2 h to obtain a carrier liquid; S3. Dissolve ferric nitrate and aluminum chloride in an ethanol solution with an alcohol concentration of 60% at a molar ratio of 1:1, add 1,3 - bis(diphenylphosphinopropane)dichloronickel, and adjust the pH value to 4.5 to obtain an impregnating solution; S4. Mix the carrier liquid and the impregnating solution at a mass ratio of 1.2:1.5, then perform centrifugal drying to obtain a composite catalyst.

[0043] In step one, the mass ratio of the composite catalyst to diphenylethane is 3.5:1.

[0044] In step one, the mass ratio of bromine to diphenylethane is 20:1.

[0045] In S3, by mass ratio, the dosage of 1,3 - bis(diphenylphosphinopropane)dichloronickel to the dry matrix mass of decarboxylated activated kaolin is 0.4:1.

[0046] In S4, after the carrier liquid and the impregnating solution are mixed, ultrasonic treatment for 37 min is also required, and the ultrasonic treatment frequency is 57 kHz.

[0047] In S4, after ultrasonic treatment, the mixed solution needs to be left standing for aging for 13 h.

[0048] In S4, after centrifugal drying, the obtained powder particles need to be further calcined in an autoclave at 370 °C for 3.5 h to obtain a composite catalyst.

[0049] Example 4: The difference between this example and Example 1 is as follows: Step one. Feed bromine and the composite catalyst into the reaction kettle, stir and mix, adjust the temperature in the reaction kettle to 30 °C, the pressure to 10 KPa, and the stirring time to 30 min; after stirring is completed, add molten diphenylethane into the reaction kettle and continue stirring for 4 h; Step two. Heat the reaction kettle in step one to 50 °C, the pressure to 10 KPa, and the reaction time to 5 h; Step three. Heat the reaction kettle in step two to 60 °C, the pressure to 10 KPa, and the reaction time to 6 h; Step 4: First, filter the reaction solution to recover the composite catalyst; then add deionized water to the reaction solution, with the mass ratio of the reaction solution to deionized water being 1.2. Heat the reaction kettle to 90 °C to recover the evaporated bromine; then add a saturated sodium sulfite solution to adjust the pH value to 7.5, and cool down to 70 °C to obtain the pretreated material. The preparation method of the composite catalyst is as follows: S1: Select hard kaolin with a kaolin content of ≥95% and crush it to 400 meshes. Then send the hard kaolin to a high-temperature kiln for high-temperature roasting for 6 h to obtain decarboxylated activated kaolin. S2: Take a 5% cetyltrimethylammonium bromide-ethanol solution, mix it with the decarboxylated activated kaolin in a mixing kettle at a solid-liquid ratio of 1:5. Then perform ultrasonic treatment for 30 min at a frequency of 40 kHz. Then heat the mixing kettle to 140 °C, adjust the pressure in the kettle to 0.8 MPa, and react for 3 h to obtain the carrier liquid. S3: Dissolve ferric nitrate and aluminum chloride in an ethanol solution with an alcohol concentration of 60% at a molar ratio of 1:1, add 1,3-bis(diphenylphosphinopropane)dichloronickel, and adjust the pH value to 4.3 to obtain the impregnation solution. S4: Mix the carrier liquid and the impregnation solution at a mass ratio of 1.5:2, and then perform centrifugal drying to obtain the composite catalyst.

[0050] In Step 1, the mass ratio of the composite catalyst to diphenylethane is 4:1.

[0051] In Step 1, the mass ratio of bromine to diphenylethane is 24:1.

[0052] In S3, by mass ratio, the dosage of 1,3-bis(diphenylphosphinopropane)dichloronickel to the dry matrix of the decarboxylated activated kaolin is 0.6:1.

[0053] In S4, after mixing the carrier liquid and the impregnation solution, ultrasonic treatment for 40 min is also required, and the ultrasonic treatment frequency is 60 kHz.

[0054] In S4, after ultrasonic treatment, the mixed solution needs to be left standing for aging for 15 h.

[0055] In S4, after centrifugal drying, the obtained powder particles need to be further roasted in a high-pressure kettle at 400 °C for 4 h to obtain the composite catalyst.

[0056] Comparative Example 1: The difference between this comparative example and Example 1 is that an ordinary catalyst is used instead of the composite catalyst.

[0057] Comparative Example 2: The difference between this comparative example and Example 1 is that the composite catalyst was not modified with cetyltrimethylammonium bromide-ethanol solution.

[0058] Take the finished products of decabromodiphenylethane in Examples 1-3 and Comparative Examples 1-2 and test their various parameters. Among them, for the whiteness stability, the obtained finished decabromodiphenylethane was treated at 250 °C for 3 h and then the whiteness was retested.

[0059]

[0060] The determination method of free bromine in this scheme is ion chromatography.

[0061] It can be seen from the comparison between Examples 1-4 and Comparative Examples 1-2 that by using cetyltrimethylammonium bromide-ethanol solution to modify kaolin and introducing 1,3-bis(diphenylphosphinopropane)dichloronickel, the composite catalyst can have a strong adsorption and activation effect on bromine molecules and diphenylethane, and there are more reaction paths and selectivities in the catalytic reaction of bromine and diphenylethane. It can also form a specific complex with the reaction intermediate, stabilize the transition state during the reaction process, guide the reaction to proceed in a specific direction, improve the selectivity of the reaction, make the generated decabromodiphenylethane have higher purity and fewer by-products.

[0062] The present invention is not limited to the above specific embodiments. Those of ordinary skill in the art starting from the above concepts and making various transformations without creative labor fall within the protection scope of the present invention.

Claims

1. A preparation method of decabromodiphenylethane, characterized in that, It includes the following steps: Step 1: Feed bromine and the composite catalyst into the reaction kettle, stir and mix, adjust the temperature in the reaction kettle to 15 - 30 °C, the pressure to -20 - 10 KPa, and the stirring time to 20 - 30 min; after stirring, add molten diphenylethane into the reaction kettle and continue stirring for 2 - 4 h; Step 2: Heat up the reaction kettle in Step 1 to 40 - 50 °C, the pressure to -5 - 10 KPa, and the reaction time to 3 - 5 h; Step 3: Heat up the reaction kettle in Step 2 to 55 - 60 °C, the pressure to -5 - 10 KPa, and the reaction time to 4 - 6 h to obtain the reaction solution; Step 4: First, filter the reaction solution to recover the composite catalyst; then add deionized water to the reaction solution, and the mass ratio of the reaction solution to deionized water is 1:(0.9 - 1.2), heat up the reaction kettle to 80 - 90 °C to recover the evaporated bromine; then add saturated sodium sulfite solution to adjust the pH value to 6.5 - 7.5, and cool down to 60 - 70 °C to obtain the pretreated material; Step 5: Cool the pretreated material to 15 - 30 °C, then wash and separate the solid and liquid to obtain the crude product; grind, wash, dry the crude product material, and perform air flow pulverization to obtain high - whiteness decabromodiphenylethane; The composite catalyst includes a carrier particle and a pre - catalyst. The carrier particle is modified kaolin powder, and the pre - catalyst is ferric nitrate and aluminum chloride.

2. The preparation method of decabromodiphenylethane according to claim 1, wherein, The preparation method of the composite catalyst is as follows: S1: Select hard kaolin with a kaolin content of ≥95% and crush it to 200 - 400 meshes, then send the hard kaolin to a high - temperature kiln for high - temperature roasting for 5 - 6 h to obtain decarboxylated activated kaolin; S2: Take a cetyltrimethylammonium bromide - ethanol solution with a mass concentration of 3 - 5%, mix it with the decarboxylated activated kaolin in a mixing kettle at a solid - liquid ratio of 1:(3 - 5), then perform ultrasonic treatment at a frequency of 30 - 40 kHz for 20 - 30 min, then heat up the mixing kettle to 120 - 140 °C, adjust the pressure in the kettle to 0.6 - 0.8 MPa, and the reaction time is 1 - 3 h to obtain the carrier liquid; S3: Dissolve ferric nitrate and aluminum chloride in an ethanol solution with an alcohol concentration of 60% at a molar ratio of 1:1, add 1,3 - bis(diphenylphosphinopropane)dichloronickel, and adjust the pH value to 4.5 ± 0.2 to obtain the impregnation liquid; S4: Mix the carrier liquid and the impregnation liquid at a mass ratio of (1 - 1.5):(1 - 2), then perform centrifugal drying to obtain the composite catalyst.

3. The preparation method of decabromodiphenylethane according to claim 1, wherein, In Step 1, the mass ratio of the composite catalyst to diphenylethane is 2.5 - 4:

1.

4. The preparation method of decabromodiphenylethane according to claim 1, wherein, In Step 1, the mass ratio of bromine to diphenylethane is 15 - 24:

1.

5. The preparation method of decabromodiphenylethane according to claim 2, characterized in that, In S1, the specific surface area of the decarboxylated activated kaolin ≥ 300 m 2 / g, and the thermal stability ≥ 1000 °C.

6. The preparation method of decabromodiphenylethane according to claim 2, wherein, In S3, by mass ratio, the dosage of 1,3 - bis(diphenylphosphinopropane)dichloronickel to the dry matrix mass of the decarboxylated activated kaolin is (0.3 - 0.6):

1.

7. The preparation method of decabromodiphenylethane according to claim 2, wherein, In S4, after mixing the carrier liquid and the impregnation liquid, it is also necessary to perform ultrasonic treatment for 30 - 40 min, and the ultrasonic treatment frequency is 50 - 60 kHz.

8. The preparation method of decabromodiphenylethane according to claim 7, wherein, In S4, after ultrasonic treatment, it is necessary to let the mixed liquid stand for aging for 10 - 15 h.

9. The preparation method of decabromodiphenylethane according to claim 2, wherein, In S4, the powder particles obtained after centrifugal drying need to be further calcined in an autoclave at 300-400 °C for 2-4 h to obtain the composite catalyst.

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