Method for improving esterification reaction efficiency of trioctyl trimellitate

Abstract

The invention relates to the technical field of organic synthesis processes, in particular to a method for improving esterification reaction efficiency of trioctyl trimellitate. Comprising the following steps: adding octanol into a reaction kettle I, heating to 150-180 DEG C, and carrying out heat preservation and temporary storage; adding solid trimellitic anhydride into a reaction kettle II, heating until the solid trimellitic anhydride is dissolved, then adding a modified tetraisopropyl titanate catalyst and activated carbon, and then transferring materials in the reaction kettle II into the reaction kettle I; and heating the reaction kettle I to 200-220 DEG C, and carrying out esterification reaction. According to the method, the modified tetraisopropyl titanate catalyst and the activated carbon are added into the dissolved trimellitic anhydride to accelerate the subsequent esterification reaction and improve the subsequent conversion rate, the activated carbon is used for synchronously adsorbing impurities generated in the subsequent esterification reaction, and then the activated carbon and the octanol are mixed and react, so that the conversion rate is improved to 98% or above. In the step 3, the temperature in the reaction kettle I is controlled in a gradient manner, so that the reaction is balanced, the esterification reaction is promoted to be carried out more thoroughly, and the conversion rate is further improved.

Description

Technical Field

[0001] This invention relates to the field of organic synthesis technology, and in particular to a method for improving the esterification efficiency of trioctyl trimellitate. Background Technology

[0002] Trioctyl trimellitate is a heat-resistant and durable primary plasticizer suitable for various plastics such as polyvinyl chloride and vinyl chloride copolymers. It also combines the advantages of polyester plasticizers and monomer plasticizers: better compatibility, plasticizing performance, low-temperature performance, migration resistance, water extraction resistance, and thermal stability than polyester plasticizers, as well as excellent electrical properties.

[0003] The company's production technology for trioctyl trimellitate is relatively mature, but during the production process, it was found that the esterification reaction conversion rate was 96%, which still did not reach the expected conversion rate of 98%. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for improving the esterification efficiency of trioctyl trimellitate with high esterification conversion rate.

[0005] To solve the above-mentioned technical problems, the technical solution of the present invention is: a method for improving the esterification reaction efficiency of trioctyl trimellitate, the innovation of which is: including the following steps: Step 1: Add octanol to reaction vessel 1 and heat to 150-180℃ for temporary storage; Step 2: Add a measured amount of solid trimellitic anhydride to reactor 2, heat to 180-200℃ until the solid trimellitic anhydride dissolves, then add modified tetraisopropyl titanate catalyst and activated carbon. The added modified tetraisopropyl titanate catalyst accelerates the subsequent esterification reaction and improves the subsequent conversion rate. The activated carbon simultaneously adsorbs the impurities generated in the subsequent esterification reaction. Transfer the material in reactor 2 to reactor 1.

[0006] Step 3: Heat the reactor to 200-220℃ to carry out the esterification reaction; Step 4: When the acid value is <0.05mgKOH / g, cool down to 140℃ and filter to obtain the product. Take a sample to analyze the purity and resistivity.

[0007] Furthermore, in step two, high-purity nitrogen is used to slowly press the material in reactor two into reactor one, avoiding contact between the material and air.

[0008] Furthermore, in step three, the temperature in reactor one is controlled using a gradient to balance the reaction and improve product purity. The first stage involves heating the reactor to 205°C and evacuating it to -45~-55KPa to carry out a preliminary esterification reaction. The second stage involves heating the reactor to 220°C for a reduced-pressure reaction to promote a more thorough esterification reaction and further improve the conversion rate.

[0009] Furthermore, in step four, diatomaceous earth and silica sand are added to reactor one for stirring and filtration. This utilizes diatomaceous earth and silica sand for fine and coarse filtration respectively, combining them to improve filtration efficiency and deeply remove trace impurities and polar byproducts, resulting in a product volume resistivity of 15-20 × 10⁻⁶. 11 Ω·cm.

[0010] Furthermore, the reaction time of the first stage is 0.5 to 1 hour; the reaction time of the second stage is 5.5 to 6 hours. The two stages are combined to promote a more thorough esterification reaction and further improve the conversion rate.

[0011] Furthermore, the modified tetraisopropyl titanate catalyst is obtained by mixing polyvinyl alcohol and tetraisopropyl titanate in a certain proportion, which can improve the catalytic stability of tetraisopropyl titanate, significantly improve the reaction rate and selectivity, and optimize the product purity and yield.

[0012] Furthermore, the polyvinyl alcohol and tetraisopropyl titanate are in a mass ratio of 1~4:100.

[0013] The advantages of this invention are: 1. The modified tetraisopropyl titanate catalyst in this invention is obtained by mixing polyvinyl alcohol and tetraisopropyl titanate in a certain proportion, thereby improving the catalyst activity. In the production process, the modified tetraisopropyl titanate catalyst and activated carbon are first added to the dissolved trimellitic anhydride, and then mixed and reacted with octanol. This can accelerate the subsequent esterification reaction and improve the subsequent conversion rate. The activated carbon is used to simultaneously adsorb impurities generated in the subsequent esterification reaction. By improving the catalyst activity, the activation energy of the reaction is reduced, thereby accelerating the reaction rate and improving the purity of the product, so that the conversion rate is increased to over 98%.

[0014] 2. In step three, the temperature in reactor one is controlled by a gradient to balance the reaction, promote a more thorough esterification reaction, and further improve the conversion rate and product purity.

[0015] 3. By adding diatomaceous earth and silica sand for stirring and filtration, fine and coarse filtration are performed using diatomaceous earth and silica sand respectively. This combined approach enhances the filtration effect, deeply removing trace impurities and polar byproducts, resulting in a product volume resistivity of 15-20 × 10⁻⁶. 11 Ω·cm. Attached Figure Description

[0016] Figure 1 This is a structural diagram of the present invention. Detailed Implementation

[0017] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0018] like Figure 1 The method shown includes the following steps to improve the esterification efficiency of trioctyl trimellitate: Step 1: Add octanol to reactor 1 and heat it to 150-180℃ for temporary storage. The reactor 1 is equipped with a first feeding port 3. Step 2: Add a measured amount of solid trimellitic anhydride to reactor 2 and heat to 180-200℃ until the solid trimellitic anhydride dissolves. Then add modified tetraisopropyl titanate catalyst and activated carbon. The added modified tetraisopropyl titanate catalyst accelerates the subsequent esterification reaction and improves the subsequent conversion rate. The activated carbon simultaneously adsorbs the impurities generated in the subsequent esterification reaction. Use high-purity nitrogen to slowly press the material in reactor 2 into reactor 1 to avoid contact between the material and air.

[0019] A second feeding port 4 is provided at the top of reactor 2, and reactor 1 and reactor 2 are connected by a pipeline. Modified tetraisopropyl titanate catalyst and activated carbon are fed into reactor 2 through the second feeding port 4.

[0020] Step 3: Heat reactor 1 to 200-220℃ to carry out the esterification reaction; Furthermore, the temperature in this step is controlled using a gradient to balance the reaction and improve product purity. The first stage involves heating reactor 1 to 205°C and evacuating it to -45~-55KPa to carry out a preliminary esterification reaction. The second stage involves heating reactor 1 to 220°C for a reduced-pressure reaction to promote a more thorough esterification reaction and increase the conversion rate.

[0021] Step 4: Once the acid value is <0.05 mg KOH / g, cool to 140℃. Add diatomaceous earth and silica sand to reactor 1 through the first feed port 3, and stir and filter. Use diatomaceous earth and silica sand for fine and coarse filtration respectively, combining them to improve filtration efficiency and deeply remove trace impurities and polar byproducts, achieving a product volume resistivity of 15-20 × 10⁻⁶. 11 Ω·cm.

[0022] Experimental Example 1 A method for improving the esterification efficiency of trioctyl trimellitate includes the following steps: 1. At room temperature, add 450g of octanol to reactor 1 and heat to 170℃ for temporary storage. 2. Add 160g of solid trimellitic anhydride to reactor 2 and heat to 180℃ until the solid trimellitic anhydride is completely dissolved. Add 1.4g of activated carbon and 0.3g of modified tetraisopropyl titanate. Pressurize the material in reactor 2 to reactor 1 using high-purity nitrogen. 3. Heat reactor 1 to 200℃, evacuate to -50KPa, and once the vacuum requirement is met, heat to 220℃ to carry out the reduced pressure reaction; 4. When the acid value is <0.05mgKOH / g, the temperature is lowered to 140℃. 0.03g of diatomaceous earth and silica sand are added and filtered to obtain the product. Samples are taken for analysis of purity and resistivity. 5. Sample the product and test its purity and resistivity.

[0023] Experimental Example 2 All other steps and parameters are the same as in Experimental Example 1, except that the amount of modified tetraisopropyl titanate is replaced with 0.25g.

[0024] Experimental Example 3 All other steps and parameters are the same as in Experiment Example 1, except that the temperature inside reactor 1 in the second stage of step 3 is adjusted to 215℃.

[0025] Experiment Example 4 All other steps and parameters are the same as in Experiment Example 1, except that the temperature inside reactor 1 in the second stage of step 3 is adjusted to 200℃.

[0026] Experiment Example 5 All other steps and parameters are the same as in Experiment Example 1, except that the temperature inside reactor 1 in step 3 is adjusted to 200℃ and the amount of modified tetraisopropyl titanate is replaced with 0.25g.

[0027] Experimental Example 6 All other steps and parameters are the same as in Experiment Example 1, except that the temperature inside reactor 1 in step 3 is adjusted to 210℃.

[0028] Experiment Example 7 All other steps and parameters are the same as in Experiment Example 1, except that the temperature in reactor 1 in step 3 is adjusted to 210℃ and the amount of modified tetraisopropyl titanate is replaced with 0.25g.

[0029] Experiment Example 8 All other steps and parameters are the same as in Experiment Example 1, except that the temperature in the first stage of step three is adjusted to 210℃.

[0030] Experiment Example 9 All other steps and parameters are the same as in Experiment Example 1, except that the temperature in the first stage of step three is adjusted to 205℃.

[0031] Experiment 10 All other steps and parameters are the same as in Experiment Example 1, except that the temperature in the first stage of step three is adjusted to 205℃ and the modified tetraisopropyl titanate is replaced with tetraisopropyl titanate.

[0032] Comparative Example 1 The method employed is a pre-existing technique for the direct synthesis of trioctyl trimellitate from liquid trimellitic anhydride, comprising the following steps: S1. Add 450g of octanol to the esterification reactor and heat the esterification reactor to 170℃. Then, through the pipeline, transport 160g of the purified, un-clumped liquid trimellitic anhydride prepared in the workshop at 180℃ to the esterification reactor. After mixing and stirring, add 1.4g of activated carbon and turn on nitrogen protection. Keep the esterification reactor warm and drain water for 0.5h. S2. Add 0.3g of tetraisopropyl titanate to the esterification vessel, heat to 200℃ and keep warm for 2-6 hours; S3. When the acid value is <0.05mgKOH / g, esterification is complete. Under negative pressure, most of the octanol in the reaction solution is extracted and sampled for analysis.

[0033] Comparative Example 2 All other parameters and steps are the same as in Comparative Example 1, except that the amount of tetraisopropyl titanate is replaced with 0.25g.

[0034] Comparative Example 3 All other parameters and steps are the same as in Comparative Example 1, except that the temperature in S2 is adjusted to 210℃.

[0035] Comparative Example 4 All other parameters and steps are the same as in Comparative Example 1, except that the temperature in S2 is adjusted to 210℃ and the amount of tetraisopropyl titanate is replaced with 0.25g.

[0036] The products obtained from Experiment Examples 1-10 were sampled and analyzed. The purity indicators are detailed in Table 1 below: Temperature in reactor 1 (°C) Temperature in reactor 2 (°C) The temperature of the first stage of the esterification reaction is ℃. The temperature of the second stage of the esterification reaction is ℃. catalyst g Finished product ester content % Resistivity (Ω·cm) 1 172.2 180.8 200.2 220.7 0.3 98.76 <![CDATA[21.34×10 11 ]]> 2 171.7 181.3 200.6 221.2 0.25 98.56 <![CDATA[20.52×10 11 ]]> 3 170.9 180.2 200.3 215.3 0.3 98.69 <![CDATA[19.78×10 11 ]]> 4 170.3 181.1 201.1 200.1 0.3 98.33 <![CDATA[19.91×10 11 ]]> 5 171.1 181.1 200.3 200.3 0.25 98.13 <![CDATA[19.02×10 11 ]]> 6 171.3 180.6 210.7 210.7 0.3 98.51 <![CDATA[20.13×10 11 ]]> 7 170.6 180.8 210.6 210.6 0.25 98.42 <![CDATA[19.98×10 11 ]]> 8 170.4 180.2 210 220 0.3 98.71 <![CDATA[20.89×10 11 ]]> 9 170.3 180.6 205 220 0.3 98.84 <![CDATA[22.13×10 11 ]]> 10 170.3 180.6 205 220 0.3 97.53 <![CDATA[18.93×10 11 ]]> It can be seen from the above table 1: Comparing Experiment 9 and 10, it can be seen that, under the same conditions, the product obtained by using the modified tetraisopropyl titanate catalyst has a higher lipid content. Comparing Experiment 1 and 2, it can be seen that, under the same conditions, the more modified tetraisopropyl titanate catalyst is used, the higher the lipid content of the product is obtained. Comparing experimental examples 1, 3, 4, 8, and 9, it can be seen that, under the same conditions, the product with a higher lipid content is obtained when the temperature of the first stage in the third step is 205℃, and the product with a higher lipid content is obtained when the temperature of the second stage in the third step is 220℃.

[0037] The products obtained from Comparative Examples 1, 2, 3, and 4 were sampled and analyzed in comparison with those from Experimental Examples 4, 5, 6, and 7. The purity indicators are detailed in Table 2 below: Comparative Example 1 Experiment Example 4 Comparative Example 2 Experiment Example 5 Comparative Example 3 Experimental Example 6 Comparative Example 4 Experiment Example 7 Finished product ester content % 96.38 98.33 96.78 98.13 96.81 98.51 92.21 98.42 Resistivity (Ω·cm) <![CDATA[16.87×10 11 ]]> <![CDATA[19.91×10 11 ]]> <![CDATA[17.83×10 11 ]]> <![CDATA[19.02×10 11 ]]> <![CDATA[17.21×10 11 ]]> <![CDATA[20.13×10 11 ]]> <![CDATA[17.54×10 11 ]]> <![CDATA[19.98×10 11 ]]> As can be seen from Table 2 above: The products obtained using this method all have an ester content of over 98% and a resistivity of 15-20 × 10⁻⁶. 11 Within the Ω·cm range, this indicates that the method can improve the conversion rate of the esterification reaction of trioctyl trimellitate.

[0038] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for improving the esterification efficiency of trioctyl trimellitate, characterized in that: Includes the following steps: Step 1: Add octanol to reaction vessel 1 and heat to 150-180℃ for temporary storage; Step 2: Add a measured amount of solid trimellitic anhydride to reactor 2, heat to 180-200℃ until the solid trimellitic anhydride dissolves, then add modified tetraisopropyl titanate catalyst and activated carbon, and finally transfer the material in reactor 2 to reactor 1. Step 3: Heat the reactor to 200-220℃ to carry out the esterification reaction; Step 4: When the acid value is <0.05mgKOH / g, cool down to 140℃ and filter to obtain the product. Take a sample to analyze the purity and resistivity.

2. The method for improving the esterification efficiency of trioctyl trimellitate according to claim 1, characterized in that: In step two, high-purity nitrogen is used to slowly press the material in reactor two into reactor one, avoiding contact between the material and air.

3. The method for improving the esterification efficiency of trioctyl trimellitate according to claim 1, characterized in that: In step three, the temperature in reactor one is controlled using a gradient to balance the reaction and improve product purity. The first stage involves heating the reactor to 205°C and evacuating it to -45~-55KPa to carry out a preliminary esterification reaction. The second stage involves heating the reactor to 220°C for a reduced-pressure reaction.

4. The method for improving the esterification efficiency of trioctyl trimellitate according to claim 1, characterized in that: In step four, diatomaceous earth and silica sand are added to reactor one and stirred and filtered.

5. The method for improving the esterification efficiency of trioctyl trimellitate according to claim 3, characterized in that: The reaction time for the first stage is 0.5 to 1 hour; the reaction time for the second stage is 5.5 to 6 hours.

6. The method for improving the esterification efficiency of trioctyl trimellitate according to claim 1, characterized in that: The modified tetraisopropyl titanate catalyst is obtained by mixing polyvinyl alcohol and tetraisopropyl titanate in a certain proportion.

7. The method for improving the esterification efficiency of trioctyl trimellitate according to claim 6, characterized in that: The polyvinyl alcohol and tetraisopropyl titanate are in a mass ratio of 1~4:100.

Images