Disclosure of Invention
In order to reduce the using amount of a catalyst and improve the safety of the production of the bis (2-propyl heptyl) terephthalate, the application provides a production method of the bis (2-propyl) heptyl terephthalate.
The application provides a production method of bis (2-propyl) heptyl terephthalate, which adopts the following technical scheme:
a method for producing bis (2-propyl) heptyl terephthalate, comprising the steps of:
step 1, preparing raw materials, namely weighing 2-propyl-1-heptanol, terephthalic acid and tetraisopropyl titanate, wherein the molar ratio of the 2-propyl-1-heptanol to the terephthalic acid is 2.0-4.0: 1, the dosage of the tetraisopropyl titanate is 0.01 to 0.20 percent of the total mass of the 2-propyl-1-heptanol and the terephthalic acid;
step 2, esterification reaction, namely mixing and stirring the raw materials prepared in the step 1 at the temperature of 170-245 ℃ for 2-5 hours to obtain a crude product;
step 3, post-treatment, namely neutralizing the crude product and washing the neutralized crude product for 1 to 3 times;
and 4, decoloring, namely cooling the product subjected to the post-treatment in the step 3, decoloring and filtering to obtain a final product.
By adopting the technical scheme, the application limits the molar ratio of the 2-propyl-1-heptanol to the terephthalic acid, and reduces the using amount of the tetraisopropyl titanate, thereby improving the safety of the application.
Preferably, in the preparation of the starting material in step 1, the molar ratio of 2-propyl-1-heptanol to terephthalic acid is 3.0 to 4.0: 1.
by adopting the technical scheme, the molar ratio of the 2-propyl-1-heptanol to the terephthalic acid is further limited, so that the product yield and the product purity can be comprehensively improved.
Preferably, the esterification reaction of step 2 specifically comprises the following steps:
step 21, premixing raw materials, and uniformly stirring 75-85% of the weight of 2-propyl-1-heptanol and the mixing rate of all terephthalic acid at the room temperature at the speed of 80-110r/min to obtain a premix A;
and step 22, reacting the raw materials, sequentially adding 15-25% of the mass of the tetraisopropyl titanate catalyst and the 2-propyl-1-heptanol into the premix A at the temperature of 170-245 ℃, and mixing and stirring for 2-5 hours to obtain a crude product.
By adopting the technical scheme, the 2-propyl-1-heptanol is put into the reactor in batches at different temperatures, so that the mixing efficiency of the raw materials is improved, the 2-propyl-1-heptanol and terephthalic acid are fully reacted, and the purity and the yield of the product are improved.
Preferably, the step 22 of raw material reaction specifically comprises the following steps:
step 221, pre-esterification, adding all catalysts into the premix A at the temperature of 170-;
step 222, post-esterification, heating to 215 ℃ and 245 ℃ at the speed of 2-5 ℃/min, mixing and stirring the residual 2-propyl-1-heptanol and the mixed solution B for 2-5 hours, and stirring to obtain a crude product.
By adopting the technical scheme, the raw material reaction step is divided into two sections of esterification reaction by adopting a sectional esterification method at different temperatures, so that the product selectivity is improved, the side reaction is inhibited, the product purity is improved, and the product chromaticity is improved.
Preferably, the post-esterification in step 222 specifically comprises the following steps:
step 2221, heating to 215-220 ℃ at a rate of 2-5 ℃/min, and mixing the rest 2-propyl-1-heptanol with the mixed solution B and stirring uniformly to obtain a mixed solution C;
step 2222, the temperature is raised in the second step, the temperature is continuously raised to 225-245 ℃ at the speed of 2-5 ℃/min, the mixed solution C is mixed and stirred for 2-5 hours to obtain a crude product, and the vapor phase component generated by the reaction is separated from the crude product for the post-treatment in the step 3.
By adopting the technical scheme, the post-esterification step is subjected to two-stage esterification reaction by means of sectional esterification, so that the product selectivity is further improved, the side reaction is inhibited, and the reaction is promoted to be carried out in the forward direction by separating water in time, thereby being beneficial to improving the yield of the product.
Preferably, the post-treatment of step 3 specifically comprises the following steps:
step 31, dealcoholization, namely condensing vapor phase components generated by the reaction and then performing first alcohol-water separation, wherein alcohol obtained by the first alcohol-water separation is used as a raw material in the esterification reaction step in the step 1;
step 32, neutralization treatment;
and step 33, water washing treatment, namely washing the neutralized crude product for 1-3 times by using the water obtained after the first alcohol-water separation in the step 31.
By adopting the technical scheme, because the first alcohol-water separation is adopted, the water of the first alcohol-water separation is used for water washing treatment, and the alcohol of the first alcohol-water separation is recycled as the raw material, so that the production cost is reduced, and the recycling of the alcohol and the water is realized.
Preferably, the neutralization treatment in step 32 is specifically: cooling the dealcoholized crude product to 100 ℃, and then adding sodium hydroxide solution to neutralize the crude product until the pH value is 7-7.5.
By adopting the technical scheme, the acid value of the product is adjusted by adding the sodium hydroxide solution.
Preferably, in the step 4, the product after being washed by water in the step 33 is subjected to the following treatment: heating the product neutralized in the step 32 to 180 ℃ and 190 ℃, stripping for 1-3h, and keeping the temperature of the stripped product for 0.5-1 h.
By adopting the technical scheme, the stripping operation is favorable for removing the soluble stripping and volatile substances in the product, thereby being favorable for the subsequent alcohol-water separation.
Preferably, in the step 4, after the steam-stripped vapor phase component is separated from the heat-preserved product, the steam-stripped vapor phase component is subjected to second alcohol-water separation; wherein the water of the second alcohol-water separation is used in the water washing treatment step of step 33; wherein the alcohol of the second alcohol-water separation is used as a raw material in the esterification reaction step of step 1.
By adopting the technical scheme, because the second alcohol-water separation is adopted, the water of the second alcohol-water separation is used for water washing treatment, and the alcohol of the second alcohol-water separation is recycled as the raw material, so that the production cost is further reduced, and the recycling of the alcohol and the water is realized.
Preferably, in the step 4, after the product separated from the stripped vapor phase component is cooled to 120 ℃ of 100-; the adsorbent comprises one or more of activated carbon and diatomaceous earth.
By adopting the technical scheme, as the adsorbent adopts one or more of the active carbon and the diatomite, the active carbon and the diatomite have excellent adsorption effect, the chromaticity and the acid value of the product can be comprehensively improved after the active carbon and the diatomite are compounded, and the diatomite has the function of assisting filtration, so that the aggregation state of particles is reduced, thereby being beneficial to filtering and removing more impurities and further being beneficial to improving the purity of the product.
In summary, the present application has the following beneficial effects:
1. the application provides a method for preparing a low-toxicity terephthalic acid di (2-propyl) heptyl ester product, the molar ratio of 2-propyl-1-heptanol to terephthalic acid is limited, the using amount of tetraisopropyl titanate is reduced, and therefore the safety of the method provided by the application is improved.
2. The method improves the mixing efficiency of the raw materials, reduces byproducts and improves the conversion rate and the product yield of the purified terephthalic acid by means of premixing and multistage esterification.
3. Acid-base neutralization, water washing and decoloration are adopted, so that the acid value and the chroma of the product are comprehensively reduced.
Detailed Description
The present application will be described in further detail with reference to examples and comparative examples.
Raw materials
Table 1 source table of raw materials used in the present application
Examples
Example 1
A production method of bis (2-propyl) heptyl terephthalate specifically comprises the following steps:
step 1, preparing raw materials, namely weighing 24.771kg of 2-propyl-1-heptanol, 13.000kg of terephthalic acid and 0.022kg of tetraisopropyl titanate, wherein the molar ratio of the 2-propyl-1-heptanol to the terephthalic acid is 2: 1; the dosage of the titanium tetraisopropyl ester catalyst is 0.058 percent of the total mass of the 2-propyl-1-heptanol and the terephthalic acid;
step 2, the esterification reaction specifically comprises the following steps:
step 21, premixing raw materials, namely mixing 80 percent of 2-propyl-1-heptanol and all terephthalic acid in an esterification kettle at room temperature at a rotating speed of 100r/min for 0.8h to obtain a premixed solution A;
step 22, the reaction of the raw materials specifically comprises the following steps:
step 221, pre-esterification, namely adding all catalysts into an esterification kettle containing the premix A at the temperature of 180 ℃, and mixing and stirring at the rotating speed of 100r/min for 1.5 hours to obtain a mixed solution B;
step 222, the post-esterification specifically comprises the following steps:
step 2221, heating to 220 ℃ at a rate of 3 ℃/min, adding the rest 2-propyl-1-heptanol into an esterification kettle containing the mixed solution B, and mixing and stirring for 1h to obtain a mixed solution C;
step 2222, heating up to 230 ℃ at a rate of 3 ℃/min, stirring the mixed solution C for 3 hours at a rotation speed of 100r/min to obtain a crude product, and separating vapor phase components (alcohol steam and water vapor) generated by the reaction from the crude product for post-treatment in step 3;
and 3, post-processing specifically comprises the following steps:
step 31, dealcoholization, namely introducing alcohol steam and water vapor generated in the esterification kettle into an esterification condenser for liquefaction, and then performing first alcohol-water separation by using an oil-water separator (a cyclone oil-water separator, the model of which is JHGL, Jiahang filtration equipment, Inc., of Xingxiang city), wherein alcohol obtained by the first alcohol-water separation is refluxed and then used as a raw material in the esterification reaction step of step 1;
step 32, neutralization treatment; transferring the dealcoholized crude product to a refining kettle, cooling to 100 ℃, adding sodium hydroxide solution to neutralize the dealcoholized crude product to pH 7;
step 33, water washing treatment, namely washing the neutralized crude product with water obtained after the first alcohol-water separation in the step 31 for 1-3 times;
and 4, decoloring, which specifically comprises the following steps:
step 41, steam stripping, namely heating the product neutralized in the step 32 to 185 ℃ for 2 hours, then carrying out flash point test on the product after steam stripping, wherein the flash point of the product is 230 ℃, namely the product after steam stripping is qualified, preserving the heat of the qualified product after steam stripping at 185 ℃ for 0.6 hour, separating the steam phase components (alcohol steam and water steam) after steam stripping from the product after heat preservation, and carrying out second alcohol-water separation on the separated steam phase components (alcohol steam and water steam) through an oil-water separator, wherein the water obtained by the second alcohol-water separation is used in the water washing treatment step of the step 33, and the alcohol obtained by the second alcohol-water separation is used as a raw material in the esterification reaction step of the step 1;
step 42, decoloring, namely cooling a product separated from the extracted vapor phase components to 110 ℃, transferring the cooled product into a filter (ZPG-A/B automatic deslagging filter, Zhejiang Xuan valve Co., Ltd.) for adsorption and decoloring, and filtering an adsorbent and impurities after adsorption is finished to obtain a final product; wherein the filter is internally provided with an adsorbent which consists of 10kg of active carbon and 5kg of diatomite.
Examples 2 to 9
Examples 2-9 differ from example 1 in that: the amounts of 2-propyl-1-heptanol, terephthalic acid and tetraisopropyl titanate used were varied, and are specified in table 2, wherein the tetraisopropyl titanate catalyst percentage is the mass of catalyst/(mass of terephthalic acid + mass of 2-propyl-1-heptanol) × 100%.
Table 2 examples 1-9 raw material compositions and amounts
Example 10
The difference between this embodiment and embodiment 1 is that step 2222 is different in the second temperature rise, which in this embodiment specifically is as follows: and (3) continuously raising the temperature to 220 ℃ at the speed of 3 ℃/min, stirring the mixed solution C for 3 hours at the rotating speed of 100r/min to obtain a crude product, and separating vapor phase components (alcohol steam and water vapor) generated by the reaction from the crude product for post-treatment in the step (3).
Example 11
The difference between this embodiment and embodiment 1 is that step 2221 is different in the first temperature rise, which in this embodiment specifically is as follows: heating to 230 ℃ at the speed of 3 ℃/min, adding the rest 2-propyl-1-heptanol into the esterification kettle containing the mixed solution B, and mixing and stirring for 1h to obtain a mixed solution C.
Example 12
The difference between this example and example 1 is that the reaction of the raw materials in step 22 is different, and the reaction of the raw materials in this example specifically includes the following steps:
step 221, pre-esterification, namely adding all catalysts into an esterification kettle containing the premix A at the temperature of 220 ℃, and mixing and stirring at the rotating speed of 100r/min for 1.5 hours to obtain a mixed solution B;
step 222, the post-esterification specifically comprises the following steps:
step 2221, heating in the first step, adding the rest 2-propyl-1-heptanol into the esterification kettle containing the mixed solution B at 220 ℃, and mixing and stirring for 1h to obtain a mixed solution C;
step 2222, heating, stirring the mixed solution C at 220 deg.C for 3 hours at 100r/min to obtain crude product, and separating the vapor phase components (alcohol vapor and water vapor) from the crude product for post-treatment in step 3;
example 13
The difference between this example and example 1 is that step 2 is different from the esterification reaction, and the esterification reaction in this example specifically includes the following steps:
step 21, premixing raw materials, namely mixing all 2-propyl-1-heptanol and all terephthalic acid in an esterification kettle at the room temperature for 0.8h at the rotating speed of 100r/min to obtain a premix A;
step 22, the reaction of the raw materials specifically comprises the following steps:
step 221, pre-esterification, namely adding all catalysts into an esterification kettle containing the premix A at the temperature of 180 ℃, and mixing and stirring at the rotating speed of 100r/min for 1.5 hours to obtain a mixed solution B;
step 222, the post-esterification specifically comprises the following steps:
step 2221, heating to 220 ℃ at the rate of 3 ℃/min in the first step, and mixing and stirring for 1h to obtain a mixed solution C;
step 2222, heating up to 230 ℃ at a rate of 3 ℃/min, stirring the mixed solution C for 3 hours at a rotation speed of 100r/min to obtain a crude product, and separating vapor phase components (alcohol steam and water vapor) generated by the reaction from the crude product for post-treatment in step 3.
Comparative example
Comparative examples 1 to 3
Comparative examples 1-3 differ from example 1 in that: the amounts of 2-propyl-1-heptanol, terephthalic acid and tetraisopropyl titanate used were varied and are shown in Table 3.
TABLE 3 comparative examples 1-3 raw material compositions and amounts
Comparative example 4
The comparative example differs from example 1 in that the step 3 post-treatment is different, and the post-treatment in the comparative example specifically comprises the following steps:
step 31, dealcoholization, namely introducing alcohol steam and water vapor generated in the esterification kettle into an esterification condenser for liquefaction, and then performing first alcohol-water separation by using an oil-water separator (a cyclone oil-water separator, the model of which is JHGL, Jiahang filtration equipment, Inc., of Xingxiang city), wherein alcohol obtained by the first alcohol-water separation is refluxed and then used as a raw material in the esterification reaction step of step 1;
step 32, neutralization treatment; transferring the dealcoholized crude product to a refining kettle, and cooling to 100 ℃;
step 33, water washing treatment, namely washing the neutralized crude product with water obtained after the first alcohol-water separation in the step 31 for 1-3 times;
detection method
1. And (3) detecting the purity of the product: the purity of the products in examples 1 to 13 and comparative examples 1 to 4 was checked by a gas chromatograph;
2. and (3) testing acidity: the acid value and acidity of GB/T1668-2008 plasticizer are measured, colorless ethanol is used as a solvent for dissolving a sample, phenolphthalein is used as an indicator solution, sodium hydroxide-ethanol standard titration solution is used for carrying out parallel detection twice on the products in examples 1-13 and comparative examples 1-4, if the difference value of the parallel detection twice is not more than 0.01mg/g, the arithmetic mean value of the parallel detection results of the two times is taken as the measurement result, if the difference value of the parallel detection on the two sides is more than 0.01mg/g, repeated sampling is carried out for parallel detection, and the qualified standard of the acidity of the product is not more than 0.1%;
3. the product yield is as follows: the products in examples 1 to 13 and comparative examples 1 to 4 were calculated and examined, wherein the product yield is (mass of product actually produced/mass of product calculated theoretically) × 100%;
4. product chromaticity detection: the products of examples 1-13 and comparative examples 1-4 were tested using the appearance chromaticity test of GB/T1664-1995 plasticizer.
Table 4 shows the parameters of the measured data of examples 1 to 13 and comparative examples 1 to 4
It can be seen from the combination of examples 1 to 5 and table 4 that the molar ratio of 2-propyl-1-heptanol to terephthalic acid affects the product purity and the product yield, the greater the molar ratio of 2-propyl-1-heptanol to terephthalic acid, the greater the product purity and the product yield both tend to increase and decrease, and at a molar ratio of 2-propyl-1-heptanol to terephthalic acid of 3.2:1, the product yield can reach 99.72%, and the product purity can reach 99.60%.
It can be seen from the combination of examples 5 to 9 and comparative example 1 and from table 4 that the amount of tetraisopropyl titanate used affects the product purity, product acidity, product color and product yield, that the greater the percentage of tetraisopropyl titanate catalyst, the greater the product purity and product yield both tend to increase and decrease, and that when the percentage of tetraisopropyl titanate catalyst is less than 0.010% or greater than 0.200%, both the product color and the product acidity increase.
As can be seen by combining example 7, comparative examples 2-3 and Table 4, the product yield and product purity were optimized for a 3.2:1 molar ratio of 2-propyl-1-heptanol to terephthalic acid at a given percentage of tetraisopropyl titanate catalyst.
As can be seen by combining example 7, examples 10-13 and Table 4, the premixing and multistage esterification improve the purity and yield of the product.
As can be seen by combining example 7 and comparative example 4 with table 4, the product which was not subjected to neutralization treatment had a low product purity and a high product color although the product yield was high, and thus the product purity and the product color could be improved though the product yield was slightly lowered by the neutralization treatment.
The present embodiment is only for explaining the present application, and it is not limited to the present application, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present application.