A method for recovering octanol from trihydroxyred oil to synthesize trioctyl trimellitate

Abstract

The present invention relates to the field of fine chemical product recovery, specifically a method for synthesizing trioctyl trimellitate from trihydroxy red oil and octanol, the method comprising the following steps: S1, sequentially adding pure water, trihydroxy red oil, and liquid caustic soda to a reactor, and stirring and heating; S2, heating the reactor to 60°C and then keeping warm for 3h; S3, after the reaction liquid gas phase analysis is qualified, extracting the reaction liquid, and performing negative pressure rectification of the upper oil phase, and controlling the temperature at 100-130°C; S4, after dehydration, adding the first activated carbon and stirring and decolorizing at 60°C, filtering while hot, and obtaining trihydroxy red oil recovery octanol solution. The present invention can improve the content of recovered octanol by adding pure water and controlling the concentration of liquid caustic soda in the range of 8-10%, and removes water and light components in the reaction liquid under the condition of negative pressure of 100-130°C, so that the content of finally recovered octanol is ≥98.5%, and can replace fresh octanol raw materials with a content of more than 99%, and synthesize trioctyl trimellitate whose various indicators meet industry indicators with trimellitic anhydride.

Description

Technical Field

[0001] The invention relates to the field of fine chemical product recovery, in particular to a method for recovering octanol from trihydroxy red oil to synthesize trioctyl trimellitate. Background Art

[0002] Trioctyl trimellitate is a heat-resistant and durable main plasticizer, which has the advantages of polyester plasticizer and monomer plasticizer. Its compatibility, processability and low-temperature resistance are also better than those of polyester plasticizer, and its electrical properties are excellent. It is mainly used for 105℃ grade heat-resistant wire and cable materials and other products requiring heat resistance and durability, such as plates, sheets, sealing gaskets, etc. It is also suitable for various plastics such as vinyl chloride copolymers, nitrocellulose, ethyl cellulose, polymethyl methacrylate, etc.

[0003] At present, trihydroxy red oil is produced when trimethylolpropane is produced in the workshop, wherein the trihydroxy red oil is a mixture of octanol, light components and a small amount of aldehydes. If the trihydroxy red oil is directly treated as waste liquid, a large amount of resources will be wasted. However, the octanol content recovered by the existing method is low, and when synthesizing trioctyl trimellitate, a series of problems such as a darker product color number (≥200) and a lower ester content occur. Therefore, it is urgent to design a new method for recovering octanol to solve the above problems. Summary of the invention

[0004] The invention aims to provide a method for synthesizing trioctyl trimellitate by recovering octanol from trihydroxy red oil. The method can turn the recovered octanol extracted from trihydroxy red oil into treasure. The content of the recovered octanol can be increased by adding pure water and controlling the concentration of liquid alkali within the range of 8-10%. Under the condition of negative pressure of 100-130 DEG C, water and light components in the reaction liquid are removed so that the content of the final recovered octanol is ≥98.5%. The method can replace the fresh octanol raw material with a content of more than 99% and synthesize the trioctyl trimellitate with trimellitic anhydride, wherein various indicators meet the industry indicators. The method of the invention can greatly increase the content of the recovered octanol, ensure the content of trioctyl ester and various indicators, and is suitable for popularization and use.

[0005] In order to solve the above technical problems, the present invention provides a method for recovering octanol from trihydroxy red oil to synthesize trioctyl trimellitate, the method comprising the following steps:

[0006] S1, add purified water, trihydroxy red oil and liquid alkali into the reaction kettle in sequence, and stir and heat up;

[0007] S2, raise the temperature of the reactor to 60°C and keep it warm for 3 hours, take the upper oil phase and send it to the gas phase for analysis;

[0008] S3, after the gas phase analysis of the reaction liquid is qualified, the reaction liquid is extracted, and the upper oil phase is distilled under negative pressure, and the temperature is controlled at 100-130°C;

[0009] S4, after the dehydration is completed, add the first activated carbon and stir at 60°C for decolorization, filter while hot to obtain the hydroxy red oil recovery octanol solution;

[0010] S5, sequentially adding trimellitic anhydride, trihydroxy red oil recovery octanol solution, the second activated carbon, and the catalyst into the reactor;

[0011] S6, heating the reactor to 180°C and then keeping it warm for 1h, then heating it to 200-230°C, collecting the octanol evaporated during the transesterification process, until no liquid is collected, then sampling and testing the acid value of the reaction liquid ≤0.20mgKOH / g and sending it to the gas phase;

[0012] S7, after the acid value of the reaction liquid is qualified, the reaction liquid is cooled to below 60°C, a dilute alkali solution is added to remove the unhydrolyzed catalyst, and the temperature is increased under negative pressure to remove water and remaining octanol;

[0013] S8. After the dehydration is completed, add the third activated carbon and stir to decolorize, filter while hot, and the filtrate obtained is the trioctyl trimellitate product.

[0014] Preferably, the weight ratio of pure water, hydroxychloroethylene and liquid caustic soda in S1 is 30-40%: 50-60%: 5%-10%, wherein the concentration of liquid caustic soda is controlled at 8-10% after adding pure water, hydroxychloroethylene is composed of octanol, light components and a small amount of aldehydes, and the aldehydes react with the liquid caustic soda, and the reaction equation is: RCHO+NaOH→RCOONa+H2O, and RCOONa is dissolved in the water phase.

[0015] Preferably, the heavy component content of the oil phase in the upper layer of the reaction liquid in S2 is ≤0.5%.

[0016] Preferably, the gas phase octanol content in the S3 is ≥96%, the vacuum degree is controlled at 500-1000 Pa, the removal time is 0.5-3 h, and the reflux ratio of the distillation tower is controlled at 2:5 during the distillation process.

[0017] Preferably, the amount of the first activated carbon added in S4 is 2-5% of the upper oil phase during static stratification.

[0018] Preferably, the weight ratio of trimellitic anhydride, hydroxyoctanol recovered from trihydroxyred oil, the second activated carbon and the catalyst in S5 is 20-30%: 70-80%: 2-5%: 0.5-1%.

[0019] Preferably, the catalyst in S5 is tetraisopropyl titanate.

[0020] Preferably, the dilute alkali solution in S7 is one or more of sodium carbonate, sodium bicarbonate, potassium carbonate, and potassium bicarbonate, and the amount of the dilute alkali solution added is 0.5-1% of the trioctyl trimellitate reaction solution, and the concentration of the dilute alkali solution is 0.5-1%.

[0021] Preferably, the vacuum degree in S7 is controlled at 500-1000 Pa, and the removal time is 0.3-1 h.

[0022] Preferably, the amount of the third activated carbon added in S8 is 2-5% of the trioctyl trimellitate reaction solution.

[0023] The beneficial effects of the present invention are:

[0024] The method for synthesizing trioctyl trimellitate by recovering octanol from trihydroxy red oil of the present invention uses the recovered octanol extracted from the trihydroxy red oil generated during the production of trimethylolpropane as a raw material, converts waste into treasure, and improves the utilization rate of resources. In the specific implementation process of the present invention, in particular, by adding pure water and controlling the concentration of liquid alkali in the range of 8-10% during the recovery process, the forward reaction of liquid alkali and trihydroxy red oil can be effectively promoted, so that the liquid alkali and the aldehydes of the trihydroxy red oil can fully react, and the content of recovered octanol is greatly improved. Then, under the condition of negative pressure of 100-130°C, water and light components in the reaction liquid can be removed, so that the content of the final recovered octanol is ≥98.5%, thereby ensuring the purity of the recovered octanol, the esterification rate and quality index of synthesizing trioctyl trimellitate with trimellitic anhydride, and being able to replace the fresh octanol raw material with a content of more than 99%, so that the prepared trioctyl trimellitate finished product is transparent and clear, free of impurities, and various indexes such as ester content, moisture content, acid value, etc. all meet the industry indexes. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] A method for recovering octanol from trihydroxy red oil to synthesize trioctyl trimellitate, the method comprising the following steps:

[0027] S1. Adding purified water, trihydroxy red oil and liquid caustic soda to a reactor in sequence, stirring and heating, when standing for extraction and stratification, the acid salt can be dissolved in the water phase, which can improve the forward reaction of the liquid caustic soda and trihydroxy red oil, thereby improving the purity of octanol recovery; Here, the weight ratio of purified water, trihydroxy red oil and liquid caustic soda is 30-40%: 50-60%: 5%-10%, wherein the concentration of the liquid caustic soda after adding purified water is controlled at 8-10%, at which the reaction rate of aldehydes can be increased and the content of recovered octanol can be increased, trihydroxy red oil is composed of octanol, light components and a small amount of aldehydes, and the aldehydes react with the liquid caustic soda, and the reaction equation is: RCHO+NaOH→RCOONa+H2O, RCOONa is dissolved in the water phase;

[0028] S2, heating the reactor to 60°C and keeping it warm for 3h, taking the upper oil phase and sending it to the gas phase for analysis; this temperature can ensure that the liquid alkali and aldehydes react completely, and the light components are removed by negative pressure distillation through S3; wherein, the content of heavy components in the upper oil phase of the reaction liquid is ≤0.5%, judging that the aldehydes react completely with the liquid alkali, so that the content of recovered octanol becomes higher;

[0029] S3, after the gas phase analysis of the reaction liquid is qualified, the reaction liquid is extracted, and the upper oil phase is distilled under negative pressure, and the temperature is controlled at 100-130°C; the gas phase octanol content in S3 is ≥96%, the vacuum degree is controlled at 500-1000pa, the removal time is 0.5-3h, and the reflux ratio of the distillation tower is controlled at 2:5 during the distillation process;

[0030] In this step, the trihydroxy red oil reacts with liquid alkali to eliminate by-product aldehydes, and then removes light components through negative pressure distillation, and finally the purity of the recovered octanol can be increased to ≥ 98.5%;

[0031] Here, the reflux ratio is controlled mainly to control the cost and improve the purity of the recovered octanol. When the reflux ratio is less than 2:5, the cost will be high, and when it is greater than 2:5, the impurities will increase.

[0032] S4, after the dehydration is completed, add the first activated carbon, stir at 60°C for decolorization, filter while hot, and obtain the octanol solution of trihydroxy red oil recovery; here, the first activated carbon is used to reduce the color number of the recovered octanol; the amount of the first activated carbon added is 2-5% of the upper oil phase when standing and stratifying;

[0033] S5, sequentially adding trimellitic anhydride, hydroxy red oil recovery octanol solution, second activated carbon, and catalyst into the reaction kettle; wherein the weight ratio of trimellitic anhydride, hydroxy red oil recovery octanol, second activated carbon, and catalyst is 20-30%: 70-80%: 2-5%: 0.5-1%; here, the catalyst is tetraisopropyl titanate;

[0034] S6, heating the reactor to 180°C and then keeping it warm for 1h, then heating it to 200-230°C, collecting the octanol evaporated during the transesterification process, until no liquid is collected, then sampling and testing the acid value of the reaction liquid ≤0.20mgKOH / g and sending it to the gas phase;

[0035] S7, after the acid value of the reaction liquid is qualified, the reaction liquid is cooled to below 60°C, a dilute alkali solution is added to remove the unhydrolyzed catalyst, and the temperature is increased under negative pressure to remove water and the remaining octanol; wherein the dilute alkali solution is one or more of sodium carbonate, sodium bicarbonate, potassium carbonate, and potassium bicarbonate, the amount of the dilute alkali solution added is 0.5-1% of the trioctyl trimellitate reaction liquid, and the concentration of the dilute alkali solution is 0.5-1%; the vacuum degree is controlled at 500-1000Pa, and the removal time is 0.3-1h;

[0036] S8. After the dehydration is completed, add the third activated carbon to stir and decolorize, and filter while hot to obtain the filtrate as the trioctyl trimellitate product; wherein, the amount of the third activated carbon added is 2-5% of the trioctyl trimellitate reaction solution.

[0037] In a specific embodiment of the present invention, a method for recovering octanol from trihydroxy red oil to synthesize trioctyl trimellitate comprises the following steps:

[0038] S1, sequentially add 750g of pure water, 1000g of hydroxychloroethylene, and 150g of liquid caustic soda (50%) into a reactor, and stir and heat; here, the 50% concentration of liquid caustic soda is added with the pure water to obtain a liquid caustic soda concentration of 8-10%, which can effectively promote the forward reaction of liquid caustic soda and hydroxychloroethylene, so that the aldehydes of liquid caustic soda and hydroxychloroethylene can fully react, greatly improving the content of recovered octanol;

[0039] S2. Heat to 60°C and keep warm for 3 hours. Let it stand and take the upper oil phase for gas phase analysis.

[0040] S3, after the reaction liquid gas phase analysis is qualified, the reaction liquid is extracted, and then the temperature is raised to 115°C under a negative pressure of 850pa, and the reflux ratio of the distillation tower is controlled to 2:5 to remove moisture and light components in the reaction liquid;

[0041] S4. After the dehydration is completed, 10 g of activated carbon is added and stirred at 60 ° C for decolorization, and the filtrate is filtered while hot to obtain 762 g of recovered octanol;

[0042] S5, add 200g of trimellitic anhydride, 700g of recovered octanol, 2.5g of catalyst and 2g of activated carbon into the reactor in sequence, stir and heat up;

[0043] S6, heating to 180°C and then keeping the temperature for 1h, then heating to 200-230°C, collecting a small amount of octanol evaporated during the esterification process, until no liquid is collected, then sampling and testing the acid value of the reaction liquid ≤0.20mgKOH / g and sending it to the gas phase;

[0044] S7, after the acid value of the reaction liquid is qualified, the temperature of the reaction liquid is lowered to 60°C, a dilute alkali solution is added to the reaction liquid to remove the unhydrolyzed catalyst, and the temperature is raised to 130°C for negative pressure dehydration and removal of excess recovered octanol;

[0045] S8. After dehydration, add 2g of activated carbon and stir at 100-130°C for decolorization. Filter while hot to obtain 507g of trioctyl trimellitate product.

[0046] In this embodiment, three batches of parallel experiments were conducted to recover the full analytical index of octanol and synthesize trioctyl trimellitate, and the comparison was as follows:

[0047]

[0048] Note: The finished product gas phase analysis adopts the finished product detection method of raw material octanol and trioctyl trimellitate.

[0049] In the above table, the recovered octanol of three batches of parallel experiments is compared with Comparison 1, and it is found that the octanol content of the fresh raw material in Comparison 1 is more than 99%, and the content of octanol recovered from hydroxy red oil in the present invention is between 98.5-98.9%. Although the carbonyl content of the recovered octanol in the table is much different from that of the sulfuric acid color development compared with Comparison 1, when the recovered octanol in hydroxy red oil is used for the reaction of preparing trioctyl trimellitate in the present invention, the finished product is transparent and clear without impurities, and the various indicators such as ester content, moisture content, acid value, etc. can also meet the industry indicators.

[0050] The invention can turn the recovered octanol extracted from trihydroxy red oil into treasure. By adding pure water and controlling the concentration of liquid alkali within the range of 8-10%, the forward reaction of liquid alkali and trihydroxy red oil can be effectively promoted within the range, so that the liquid alkali and the aldehydes of trihydroxy red oil can fully react, and the content of recovered octanol is greatly improved. Under the condition of negative pressure of 100-130 DEG C, water and light components in the reaction liquid are removed, so that the content of the final recovered octanol is ≥98.5%, and the fresh octanol raw material with a content of more than 99% can be replaced. The trimellitic acid trioctyl ester with various indicators that meet the industry indicators can be synthesized with trimellitic anhydride. The method of the invention can greatly improve the content of recovered octanol, ensure the content of trioctyl ester and various indicators, and is suitable for promotion and use.

[0051] The above disclosure is only the preferred embodiment of the present invention, which certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. A method for recovering octanol from trihydroxy red oil to synthesize trioctyl trimellitate, characterized in that: The method comprises the following steps: S1, add purified water, trihydroxy red oil and liquid alkali into the reaction kettle in sequence, and stir and heat up; S2, raise the temperature of the reactor to 60°C and keep it warm for 3 hours, take the upper oil phase and send it to the gas phase for analysis; S3, after the gas phase analysis of the reaction liquid is qualified, the reaction liquid is extracted, and the upper oil phase is distilled under negative pressure, and the temperature is controlled at 100-130°C; S4, after the dehydration is completed, add the first activated carbon and stir at 60°C for decolorization, filter while hot to obtain the hydroxy red oil recovery octanol solution; S5, sequentially adding trimellitic anhydride, trihydroxy red oil recovery octanol solution, the second activated carbon, and the catalyst into the reactor; S6, heating the reactor to 180°C and then keeping it warm for 1h, then heating it to 200-230°C, collecting the octanol evaporated during the transesterification process, until no liquid is collected, then sampling and testing the acid value of the reaction liquid ≤0.20mgKOH / g and sending it to the gas phase; S7, after the acid value of the reaction liquid is qualified, the reaction liquid is cooled to below 60°C, a dilute alkali solution is added to remove the unhydrolyzed catalyst, and the temperature is increased under negative pressure to remove water and remaining octanol; S8. After the dehydration is completed, add the third activated carbon and stir to decolorize, filter while hot, and the filtrate obtained is the trioctyl trimellitate product.

2. The method for recovering octanol from hydroxychloroethylene according to claim 1, characterized in that: The weight ratio of pure water, hydroxychloroethylene and liquid caustic soda in S1 is 30-40%: 50-60%: 5%-10%, wherein the concentration of liquid caustic soda is controlled at 8-10% after adding pure water. The hydroxychloroethylene is composed of octanol, light components and a small amount of aldehydes. Aldehydes react with liquid caustic soda, and the reaction equation is: RCHO+NaOH→RCOONa+H2O, and RCOONa is dissolved in the water phase.

3. The method for recovering octanol from hydroxychloroethylene oil to synthesize trioctyl trimellitate according to claim 1, characterized in that: The heavy component content of the oil phase in the upper layer of the reaction liquid in S2 is ≤0.5%.

4. The method for recovering octanol from hydroxychloroethylene oil to synthesize trioctyl trimellitate according to claim 1, characterized in that: The gas phase octanol content in the S3 is ≥96%, the vacuum degree is controlled at 500-1000 Pa, the removal time is 0.5-3 hours, and the reflux ratio of the distillation tower is controlled at 2:5 during the distillation process.

5. The method for recovering octanol from hydroxychloroethylene oil to synthesize trioctyl trimellitate according to claim 1, characterized in that: The amount of the first activated carbon added in S4 is 2-5% of the upper oil phase during static stratification.

6. The method for recovering octanol from hydroxychloroethylene oil to synthesize trioctyl trimellitate according to claim 1, characterized in that: The weight ratio of trimellitic anhydride, hydroxyoctanol recovered from trihydroxyred oil, the second activated carbon and the catalyst in S5 is 20-30%: 70-80%: 2-5%: 0.5-1%.

7. The method for recovering octanol from hydroxychloroethylene oil to synthesize trioctyl trimellitate according to claim 1, characterized in that: The catalyst in S5 is tetraisopropyl titanate.

8. The method for recovering octanol from hydroxychloroethylene oil to synthesize trioctyl trimellitate according to claim 1, characterized in that: The dilute alkali solution in S7 is one or more of sodium carbonate, sodium bicarbonate, potassium carbonate and potassium bicarbonate. The amount of the dilute alkali solution added is 0.5-1% of the trioctyl trimellitate reaction solution, and the concentration of the dilute alkali solution is 0.5-1%.

9. The method for recovering octanol from hydroxychloroethylene oil to synthesize trioctyl trimellitate according to claim 1, characterized in that: The vacuum degree in S7 is controlled at 500-1000 Pa, and the removal time is 0.3-1 h.

10. The method for recovering octanol from hydroxychloroethylene oil to synthesize trioctyl trimellitate according to claim 1, characterized in that: The amount of the third activated carbon added in S8 is 2-5% of the trioctyl trimellitate reaction solution.

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