CN100400499C - Terephthalic acid oxidation residue recovery and utilization method - Google Patents

Terephthalic acid oxidation residue recovery and utilization method Download PDF

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CN100400499C
CN100400499C CNB2003101034350A CN200310103435A CN100400499C CN 100400499 C CN100400499 C CN 100400499C CN B2003101034350 A CNB2003101034350 A CN B2003101034350A CN 200310103435 A CN200310103435 A CN 200310103435A CN 100400499 C CN100400499 C CN 100400499C
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terephthalic acid
mixed ester
isophthalate
reaction
dioctyl
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CN1611482A (en
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李红剑
黄秋明
莫馗
阙子龙
彭海珠
卢姝
陈石登
栾金义
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Sinopec Beijing Research Institute of Chemical Industry
China Petroleum and Chemical Corp
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Sinopec Beijing Research Institute of Chemical Industry
China Petroleum and Chemical Corp
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Abstract

The present invention relates to a method for recycling oxidation residues of terephthalic acid. The present invention recycles terephthalic acid, m-phthalic acid and benzoic acid in residues obtained in the production of a petrochemical industry by adopting processes of twice methyl-esterification reactions, separation with a rectification method, refinement with a recrystallization method, an ester interchange reaction, etc. The present invention solves the problems of low recycle rate, more impurities in the obtained product, etc. when the residues are recycled in the prior art. The method is mainly applied to the recycle of the oxidation residues of the terephthalic acid.

Description

The method that a kind of terephthalic acid oxidation residua is recycled
Technical field
The present invention relates to a kind of petrochemical complex and produce the method that the recoverying and utilizing method of residue, particularly terephthalic acid oxidation residua are recycled.
Background technology
Terephthalic acid is a kind of important petrochemicals, and it is a main raw material of producing polyester.Industrial production method of terephthalic acid has multiple, and wherein the p-Xylol high-temperature oxidation is topmost production method.This method is a raw material with the p-Xylol, is solvent with acetic acid, is Cobaltous diacetate, manganese acetate and tetrabromoethane catalyzer, and oxidation at high temperature generates crude terephthalic acid, and then is refined into the pure terephthalic acid.
Have a large amount of side reactions in the process of p xylene oxidation generation terephthalic acid, the by product of generation and unreacted raw material enter in the mother liquor, and mother liquor reclaims the solid impurity that produces behind the acetic acid through pervaporation and is called the terephthalic acid oxidation residua.
Isolated residue is called the purification of terephthalic acid residue in the crude terephthalic acid treating process; A large amount of waste materials of discharging when cleaning production unit enter effluent settling chamber, are called the pond material by the waste material that picks up in the effluent settling chamber; Purification of terephthalic acid residue and pond material are collectively referred to as the terephthalic acid rinsing residue.
Contain a large amount of valuable constituents in terephthalic acid oxidation residua and the terephthalic acid rinsing residue: in the terephthalic acid oxidation residua, contain terephthalic acid, m-phthalic acid and phenylformic acid, in the terephthalic acid rinsing residue, contain terephthalic acid and p-methylbenzoic acid.
In order to recycle terephthalic acid, m-phthalic acid and the phenylformic acid in the terephthalic acid oxidation residua, Chinese patent CN1228411 discloses a kind of method of producing the terephthalic acid mixed ester with terephthaldehyde's acid residue and aliphatic monobasic alcohol and dibasic alcohol ester.This method is put into terephthaldehyde's acid residue, monohydroxy-alcohol, dibasic alcohol, catalyzer and gac in the reactor that has stirring and condensation, reflux, is stirring, is carrying out esterification under the condition of heating; After esterification is finished, at first vacuumize and remove alcohol excess and low-boiling-point substance, filter then and remove gac and impurity, obtain the terephthalic acid mixed ester.
The subject matter that this method exists is: the utilization ratio of terephthalic acid, m-phthalic acid is lower in the terephthalic acid oxidation residua, and the purity of products obtained therefrom is low, and the phenylformic acid in the oxidation residua does not obtain recycling.The major cause that produces the problems referred to above is: the esterification reaction of organic acid of this method is insufficient; The complicated component of terephthaldehyde's acid residue, wherein a lot of impurity and by product enter product, influence the purity of product.
Summary of the invention
In order to solve problems such as the terephthalic acid, the m-phthalic acid utilization ratio that exist in prior art purity lower, products obtained therefrom is low, the invention provides the method that a kind of terephthalic acid oxidation residua is recycled.The present invention adopts the technological process of secondary esterification reaction of organic acid and rectifying, makes full use of the valuable material in the terephthalic acid oxidation residua, has improved the purity of utilization ratio and product, and utilizes the phenylformic acid in the oxidation residua to make the methyl benzoate product.
The method that terephthalic acid oxidation residua of the present invention is recycled is achieved in that
Contain terephthalic acid 10~60% (weight), m-phthalic acid 10~60% (weight), phenylformic acid 15~60% (weight) in the terephthalic acid oxidation residua of the present invention, this recoverying and utilizing method may further comprise the steps successively:
A. will pulverize after the described terephthalic acid oxidation residua drying;
B. oxidation residua and methyl alcohol after pulverizing carry out the esterification reaction of organic acid first time, and the weight ratio of oxidation residua and methyl alcohol is 1: 0.5~1: 5, and temperature of reaction is 150~250 ℃, and the reaction times is 1~5 hour;
C. with water and methyl alcohol in the distillation method removal esterification reaction of organic acid resultant first time;
D. remove water and methyl alcohol intermediate product and methyl alcohol afterwards and carry out the esterification reaction of organic acid second time, the weight ratio of intermediate product and methyl alcohol is 1: 0.5~1: 4, and temperature of reaction is 150~230 ℃, and the reaction times is 0.5~4 hour;
E. with rectification method by isolating mixed ester and the methyl benzoate that dimethyl terephthalate (DMT) and dimethyl isophthalate are formed the second time in the esterification reaction of organic acid resultant, the reflux ratio of rectifying is 0~5, theoretical plate number is 10~50.
In concrete enforcement the inventive method, optimum condition is: in step b, the weight ratio of oxidation residua and methyl alcohol is 1: 0.8~1: 2.0, and temperature of reaction is 180~220 ℃, and the reaction times is 2.5~3.5 hours.In steps d, the intermediate product after removal water and the methyl alcohol and the weight ratio of methyl alcohol are 1: 0.8~1: 1.6, and temperature of reaction is 170~210 ℃, and the reaction times is 1.5~2.5 hours.
With the methyl benzoate that fractional distillation refining is obtained by step e, the reflux ratio of rectifying is 0~5, and theoretical plate number is 10~50.
With the mixed ester that refining dimethyl terephthalate (DMT) that is obtained by step e of recrystallization method and dimethyl isophthalate are formed, this process for purification may further comprise the steps successively:
(a) mixed ester and the methyl alcohol of dimethyl terephthalate (DMT) and dimethyl isophthalate composition is mixed by weight 1: 1~1: 10;
(b) mixture heating up is stirred, temperature is 50~65 ℃, and the time is 1~3 hour;
(c) then mixture is cooled to room temperature, carries out solid-liquid separation;
Above-mentioned steps (a)~(c) can be carried out 1~3 time, obtains the mixed ester that purified dimethyl terephthalate (DMT) and dimethyl isophthalate are formed.
In concrete enforcement the inventive method, optimum condition is: in step (a), the mixed ester that dimethyl terephthalate (DMT) and dimethyl isophthalate are formed and the weight ratio of methyl alcohol are 1: 2~1: 5; In step (b), the mixture heating up churning time is 2~3 hours.
The mixed ester of utilizing purified dimethyl terephthalate (DMT) and dimethyl isophthalate to form prepares the mixed ester of dioctyl terephthalate and dioctyl isophthalate composition, and this product is a kind of softening agent, and this process may further comprise the steps successively:
A. the mixed ester of dimethyl terephthalate (DMT) and dimethyl isophthalate composition is mixed with isooctyl alcohol, add catalyzer, transesterification reaction is carried out in heating; The mixed ester that dimethyl terephthalate (DMT) and dimethyl isophthalate are formed and the mol ratio of isooctyl alcohol are 1: 1~1: 10, temperature of reaction is 140~240 ℃, reaction times is 1~5 hour, the catalyzer of transesterification reaction is one of tetrabutyl titanate, p-methyl benzenesulfonic acid, zinc acetate, sulfuric acid, and catalyst levels is 0.1~0.5% of a reactant gross weight;
B. with isooctyl alcohol and low-boiling-point substance in the distillation method removal product of transesterification reaction, distillation temperature is 100~200 ℃, and distillation time is 1~5 hour, obtains the mixed ester that dioctyl terephthalate and dioctyl isophthalate are formed.
In concrete enforcement the inventive method, optimum condition is: in steps A, the mixed ester that dimethyl terephthalate (DMT) and dimethyl isophthalate are formed and the mol ratio of isooctyl alcohol are 1: 2~1: 4, temperature of reaction is 180~220 ℃, reaction times is 2~3 hours, catalyzer is a tetrabutyl titanate, and catalyst levels is 0.2~0.4% of a reactant gross weight; In step B, underpressure distillation is adopted in distillation, and vacuum tightness is lower than gauge pressure-0.09MPa, and distillation temperature is 160~200 ℃, and distillation time is 2~3 hours.
Adopt alkali cleaning to add the method purified terephthalic dioctyl ester of washing and the mixed ester that dioctyl isophthalate is formed, the purified method is: mixed ester that dioctyl terephthalate and dioctyl isophthalate are formed and concentration are 5~15% 1: 5 by volume~5: 1 mixed of sodium carbonate solution, under 60~90 ℃ temperature, stirred 0.5~2 hour, carry out oily water separation afterwards, oil phase is washed 1~5 time with 1: 5~5: 1 water of volume ratio, afterwards with the moisture in the method for evaporation removal oil phase, solid impurity with in the suction method removal oil phase obtains the mixed ester that purified dioctyl terephthalate and dioctyl isophthalate are formed.
In concrete enforcement the inventive method, optimum condition is: mixed ester that dioctyl terephthalate and dioctyl isophthalate are formed and concentration are 8~10% 1: 2 by volume~2: 1 mixed of sodium carbonate solution, under 70~80 ℃ temperature, stirred 1~1.5 hour, carry out oily water separation afterwards, oil phase is washed 2~3 times with 1: 2~2: 1 water of volume ratio, afterwards with the moisture in the method for evaporation removal oil phase, solid impurity with in the suction method removal oil phase obtains the mixed ester that purified dioctyl terephthalate and dioctyl isophthalate are formed.
Adopt above treating processes, oxidation residua can reach more than 90% through the esterification yield of respective acids behind twice esterification reaction of organic acid, refining back methyl benzoate product purity can reach more than 99.5%, and obtained the mixed ester product of purified dimethyl terephthalate (DMT) and dimethyl isophthalate composition and the mixed softening agent product of dioctyl terephthalate and dioctyl isophthalate composition, the softening agent product reaches the quality standard of chemical industry standard HG/T2423-93 top grade product.
Embodiment
State technical scheme of the present invention below in conjunction with embodiment is further auspicious, protection scope of the present invention is not limited to following embodiment.
Method of the present invention can be implemented according to following process:
Esterification reaction of organic acid:
Contain terephthalic acid, m-phthalic acid and phenylformic acid in the terephthalic acid oxidation residua.Terephthalic acid, m-phthalic acid carry out esterification with methyl alcohol under high-temperature and high-pressure conditions, generate dimethyl terephthalate (DMT), dimethyl isophthalate.Reaction is carried out in two steps, at first terephthalic acid, m-phthalic acid and methanol esterification obtain terephthalic acid monomethyl ester, m-phthalic acid mono-methyl, and terephthalic acid monomethyl ester, m-phthalic acid mono-methyl continuation esterification obtain dimethyl terephthalate (DMT), dimethyl isophthalate then.Phenylformic acid in the residue and methyl alcohol generation esterification generate methyl benzoate simultaneously.
Terephthalic acid oxidation residua after will drying, pulverizing is put into autoclave, adds methyl alcohol, mixes, and heating begins reaction.After reaction is finished, cool.Reacted product is distilled, remove water in products and divide and excessive methyl alcohol, obtain the esterification product one time.
Because the esterification yield of respective acids is not high in esterification reaction of organic acid, has more mono-methyl in the product, therefore need carry out the secondary esterification reaction of organic acid, making mono-methyl continue esterification becomes dimethyl ester.The raw material of secondary esterification reaction of organic acid is an esterification product having removed moisture and excessive methanol, and the secondary esterification reaction of organic acid is identical with the process of an esterification.
The main component that the secondary esterification reaction of organic acid obtains thick ester is mixed ester and the methyl benzoate that dimethyl terephthalate (DMT) and dimethyl isophthalate are formed, next contains a spot of terephthalic acid monomethyl ester, m-phthalic acid mono-methyl and unreacted acids, also has some high boiling material etc.Utilize the difference of each boiling point substance, adopt the thick ester of method separated secondary esterification reaction of organic acid gained of rectifying, isolate mixed ester and two products of methyl benzoate that dimethyl terephthalate (DMT) and dimethyl isophthalate are formed.
Making with extra care of esterification product:
Adopt the fractional distillation refining methyl benzoate, obtain highly purified methyl benzoate product.
In the mixed ester of dimethyl terephthalate (DMT) and dimethyl isophthalate composition, contain the terephthalaldehydic acid methyl esters of trace, influenced quality product.Because terephthalaldehydic acid methyl esters, dimethyl terephthalate (DMT) are different with the variation of the solubility with temperature of dimethyl isophthalate in methyl alcohol, can adopt recrystallization method to make with extra care this product.
Add methyl alcohol in the mixed ester of dimethyl terephthalate (DMT) and dimethyl isophthalate composition, heating is cooled to room temperature then, carries out solid-liquid separation with suction method, obtains the mixed ester that purified dimethyl terephthalate (DMT) and dimethyl isophthalate are formed.For guaranteeing the quality of product, said process can carry out repeatedly.
Transesterification reaction:
The mixed ester that utilizes purified dimethyl terephthalate (DMT) and dimethyl isophthalate to form by transesterification reaction prepares the softening agent product.Under certain temperature and catalyst action, dimethyl terephthalate (DMT) and dimethyl isophthalate and isooctyl alcohol carry out transesterification reaction, can produce corresponding monooctyl ester.
Add isooctyl alcohol and catalyzer in the mixed ester of dimethyl terephthalate (DMT) and dimethyl isophthalate composition, transesterification reaction is carried out in heating, stirring.Adopt isooctyl alcohol and low-boiling-point substance in the vacuum distillation method removal product then, obtain the mixed ester product that dioctyl terephthalate and dioctyl isophthalate are formed.
Making with extra care of ester interchanged prod:
Adopt alkali cleaning to add the method purified terephthalic dioctyl ester of washing and the mixed ester product that dioctyl isophthalate is formed, remove the by product of transesterification reaction.
At first the product with transesterification reaction mixes, stirs with sodium carbonate solution, carry out oily water separation then, oil reservoir is through washing, evaporative removal moisture, suction filtration is removed solid impurity, obtains the mixed ester that purified dioctyl terephthalate and dioctyl isophthalate are formed.
Embodiment 1
Contain terephthalic acid 30% (weight), m-phthalic acid 28% (weight), phenylformic acid 35% (weight) in the terephthalic acid oxidation residua.
To pulverize after the above-mentioned residue drying; Residue and methyl alcohol after pulverizing carry out the esterification reaction of organic acid first time, and the weight ratio of residue and methyl alcohol is 1: 1.2, and temperature of reaction is 210 ℃, and the reaction times is 3 hours; Again with water and methyl alcohol in the distillation method removal esterification reaction of organic acid resultant first time; Carry out the esterification reaction of organic acid second time afterwards, removing the water and the intermediate product of methyl alcohol and the weight ratio of methyl alcohol is 1: 1, and temperature of reaction is 200 ℃, and the reaction times is 2 hours; Again with rectification method by isolating mixed ester and the methyl benzoate that dimethyl terephthalate (DMT) and dimethyl isophthalate are formed the second time in the esterification reaction of organic acid resultant, the overhead fraction reflux ratio is 1 in the rectifying, theoretical plate number is 30.
The methyl benzoate that adopts the fractional distillation refining said process to obtain, the overhead fraction reflux ratio of rectifying is 1, theoretical plate number is 30.
The mixed ester that dimethyl terephthalate (DMT) that the refining said process of employing recrystallization method obtains and dimethyl isophthalate are formed.Earlier that the mixed ester and the methyl alcohol of dimethyl terephthalate (DMT) and dimethyl isophthalate composition is mixed, the mixed ester that dimethyl terephthalate (DMT) and dimethyl isophthalate are formed and the weight ratio of methyl alcohol are 1: 3; With the said mixture heated and stirred, temperature is 65 ℃ again, and the time is 2 hours; Afterwards mixture is cooled to room temperature, carries out solid-liquid separation, obtain the mixed ester that dimethyl terephthalate (DMT) and dimethyl isophthalate are formed; Above recrystallizing and refining process is carried out 2 times altogether.
Through said process, in the terephthalic acid oxidation residua p phthalic acid esterification lead be 95%, m-phthalic acid 94%, phenylformic acid 96%, the total content of the mixed ester that dimethyl terephthalate (DMT) and dimethyl isophthalate are formed is 99%, and methyl benzoate content is 99.6%.
Embodiment 2~5
The process of embodiment 2~5 is identical with embodiment 1, the material composition of embodiment 1~5, the parameter for the treatment of processes and the results are shown in Table 1.
Table 1
Figure C20031010343500111
Embodiment 6
The mixed ester of utilizing dimethyl terephthalate (DMT) that embodiment 1 obtains and dimethyl isophthalate to form prepares the mixed ester that dioctyl terephthalate and dioctyl isophthalate are formed.
The mixed ester that dimethyl terephthalate (DMT) and dimethyl isophthalate are formed is with after isooctyl alcohol mixes, and adding catalyzer metatitanic acid four butyl esters heat, and carry out transesterification reaction.The mixed ester that dimethyl terephthalate (DMT) and dimethyl isophthalate are formed and the mol ratio of isooctyl alcohol are 1: 3, and temperature of reaction is 200 ℃, and the reaction times is 3 hours, and catalyst levels is 0.2% of a reactant gross weight.
With isooctyl alcohol and low-boiling-point substance in the underpressure distillation removal product of transesterification reaction, distillation temperature is 180 ℃ then, and distillation time is 3 hours, and vacuum tightness-0.095MPa (gauge pressure) obtains the mixed ester that dioctyl terephthalate and dioctyl isophthalate are formed.
Mixed ester that dioctyl terephthalate and dioctyl isophthalate are formed and concentration are 10% 1: 1 by volume mixed of sodium carbonate solution then, under 75 ℃ temperature, stirred 12 hours, carry out oily water separation afterwards, oil phase is washed 3 times with 1: 1 water of volume ratio, afterwards with the moisture in the method for evaporation removal oil phase, solid impurity with in the suction method removal oil phase obtains the mixed ester that purified dioctyl terephthalate and dioctyl isophthalate are formed.
Obtain the mixed softening agent that dioctyl terephthalate and dioctyl isophthalate are formed by above process, quality product reaches the requirement of national chemical industry standard HG/T2423-93 top grade product standard.
Embodiment 7~13
The process of embodiment 7~13 is identical with embodiment 6, and wherein embodiment 7 utilizes the mixed ester that embodiment 3 obtains, the mixed ester that embodiment 8,9 utilizes embodiment 4 to obtain, the mixed ester that embodiment 10,11,12,13 utilizes embodiment 1 to obtain.The parameter of embodiment 6~13 treating processess and the results are shown in Table 2.
Table 2
Figure C20031010343500121

Claims (15)

1. the method recycled of a terephthalic acid oxidation residua, according to weight percent meter, contain terephthalic acid 10~60%, m-phthalic acid 10~60%, phenylformic acid 15~60% in the described terephthalic acid oxidation residua, this recoverying and utilizing method may further comprise the steps successively:
A. will pulverize after the described terephthalic acid oxidation residua drying;
B. oxidation residua and methyl alcohol after pulverizing carry out the esterification reaction of organic acid first time, and the weight ratio of oxidation residua and methyl alcohol is 1: 0.5~1: 5, and temperature of reaction is 150~250 ℃, and the reaction times is 1~5 hour;
C. with water and methyl alcohol in the distillation method removal esterification reaction of organic acid resultant first time;
D. remove water and methyl alcohol intermediate product and methyl alcohol afterwards and carry out the esterification reaction of organic acid second time, the weight ratio of intermediate product and methyl alcohol is 1: 0.5~1: 4, and temperature of reaction is 150~230 ℃, and the reaction times is 0.5~4 hour;
E. with rectification method by isolating mixed ester and the methyl benzoate that dimethyl terephthalate (DMT) and dimethyl isophthalate are formed the second time in the esterification reaction of organic acid resultant, the reflux ratio of rectifying is 0~5, theoretical plate number is 10~50.
2. the method that a kind of terephthalic acid oxidation residua according to claim 1 is recycled is characterized in that:
In step b, the weight ratio of oxidation residua and methyl alcohol is 1: 0.8~1: 2.0, and temperature of reaction is 180~220 ℃, and the reaction times is 2.5~3.5 hours.
3. the method that a kind of terephthalic acid oxidation residua according to claim 1 is recycled is characterized in that:
In steps d, the intermediate product after removal water and the methyl alcohol and the weight ratio of methyl alcohol are 1: 0.8~1: 1.6, and the esterification reaction of organic acid temperature is 170~210 ℃, and the reaction times is 1.5~2.5 hours.
4. the method that a kind of terephthalic acid oxidation residua according to claim 2 is recycled is characterized in that:
In steps d, the intermediate product after removal water and the methyl alcohol and the weight ratio of methyl alcohol are 1: 0.8~1: 1.6, and the esterification reaction of organic acid temperature is 170~210 ℃, and the reaction times is 1.5~2.5 hours;
5. according to the method for the described a kind of terephthalic acid oxidation residua recycling of one of claim 1~4, it is characterized in that:
With the methyl benzoate that fractional distillation refining is obtained by step e, the reflux ratio of rectifying is 0~5, and theoretical plate number is 10~50.
6. according to the method for the described a kind of terephthalic acid oxidation residua recycling of one of claim 1~4, it is characterized in that:
With the mixed ester that refining dimethyl terephthalate (DMT) that is obtained by step e of recrystallization method and dimethyl isophthalate are formed, this process for purification may further comprise the steps successively:
(a) mixed ester and the methyl alcohol of dimethyl terephthalate (DMT) and dimethyl isophthalate composition is mixed by weight 1: 1~1: 10;
(b) mixture heating up is stirred, temperature is 50~65 ℃, and the time is 1~3 hour;
(c) then mixture is cooled to room temperature, carries out solid-liquid separation;
Above-mentioned steps (a)~(c) is carried out 1~3 time, obtains the mixed ester that purified dimethyl terephthalate (DMT) and dimethyl isophthalate are formed.
7. the method that a kind of terephthalic acid oxidation residua according to claim 6 is recycled is characterized in that:
In step (a), the mixed ester that dimethyl terephthalate (DMT) and dimethyl isophthalate are formed and the weight ratio of methyl alcohol are 1: 2~1: 5.
8. the method that a kind of terephthalic acid oxidation residua according to claim 6 is recycled is characterized in that:
In step (b), the time that mixture heating up stirs is 2~3 hours.
9. the method that a kind of terephthalic acid oxidation residua according to claim 7 is recycled is characterized in that
In step (b), the time that mixture heating up stirs is 2~3 hours.
10. the method that a kind of terephthalic acid oxidation residua according to claim 6 is recycled is characterized in that:
The mixed ester of utilizing purified dimethyl terephthalate (DMT) and dimethyl isophthalate to form prepares the mixed ester of dioctyl terephthalate and dioctyl isophthalate composition, and this process may further comprise the steps successively:
A. the mixed ester of dimethyl terephthalate (DMT) and dimethyl isophthalate composition is mixed with isooctyl alcohol, add catalyzer, transesterification reaction is carried out in heating; The mixed ester that dimethyl terephthalate (DMT) and dimethyl isophthalate are formed and the mol ratio of isooctyl alcohol are 1: 1~1: 10, temperature of reaction is 140~240 ℃, reaction times is 1~5 hour, the catalyzer of transesterification reaction is one of tetrabutyl titanate, p-methyl benzenesulfonic acid, zinc acetate, sulfuric acid, and catalyst levels is 0.1~0.5% of a reactant gross weight;
B. with isooctyl alcohol and low-boiling-point substance in the distillation method removal product of transesterification reaction, distillation temperature is 100~200 ℃, and distillation time is 1~5 hour, obtains the mixed ester that dioctyl terephthalate and dioctyl isophthalate are formed.
11. the method that a kind of terephthalic acid oxidation residua according to claim 10 is recycled is characterized in that:
In steps A, the mixed ester that dimethyl terephthalate (DMT) and dimethyl isophthalate are formed and the mol ratio of isooctyl alcohol are 1: 2~1: 4, temperature of reaction is 180~220 ℃, reaction times is 2~3 hours, catalyzer is a tetrabutyl titanate, and catalyst levels is 0.2~0.4% of a reactant gross weight.
12. the method that a kind of terephthalic acid oxidation residua according to claim 10 is recycled is characterized in that:
In step B, adopt underpressure distillation, vacuum tightness is lower than gauge pressure-0.09MPa, and distillation temperature is 160~200 ℃, and distillation time is 2~3 hours.
13. the method that a kind of terephthalic acid oxidation residua according to claim 10 is recycled is characterized in that:
Mixed ester that dioctyl terephthalate and dioctyl isophthalate are formed and concentration are 5~15% 1: 5 by volume~5: 1 mixed of sodium carbonate solution, under 60~90 ℃ temperature, stirred 0.5~2 hour, carry out oily water separation afterwards, oil phase is washed 1~5 time with 1: 5~5: 1 water of volume ratio, afterwards with the moisture in the method for evaporation removal oil phase, solid impurity with in the suction method removal oil phase obtains the mixed ester that purified dioctyl terephthalate and dioctyl isophthalate are formed.
14. the method that a kind of terephthalic acid oxidation residua according to claim 13 is recycled is characterized in that:
Mixed ester that dioctyl terephthalate and dioctyl isophthalate are formed and concentration are 8~10% 1: 2 by volume~2: 1 mixed of sodium carbonate solution, under 70~80 ℃ temperature, stirred 1~1.5 hour, carry out oily water separation afterwards, oil phase is washed 2~3 times with 1: 2~2: 1 water of volume ratio, afterwards with the moisture in the method for evaporation removal oil phase, solid impurity with in the suction method removal oil phase obtains the mixed ester that purified dioctyl terephthalate and dioctyl isophthalate are formed.
15. the method that a kind of terephthalic acid oxidation residua according to claim 11 is recycled is characterized in that:
In step B, adopt underpressure distillation, vacuum tightness is lower than gauge pressure-0.09MPa, and distillation temperature is 160~200 ℃, and distillation time is 2~3 hours;
Mixed ester that dioctyl terephthalate and dioctyl isophthalate are formed and concentration are 8~10% 1: 2 by volume~2: 1 mixed of sodium carbonate solution, under 70~80 ℃ temperature, stirred 1~1.5 hour, carry out oily water separation afterwards, oil phase is washed 2~3 times with 1: 2~2: 1 water of volume ratio, afterwards with the moisture in the method for evaporation removal oil phase, solid impurity with in the suction method removal oil phase obtains the mixed ester that purified dioctyl terephthalate and dioctyl isophthalate are formed.
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