WO2012119520A1

WO2012119520A1 - Method for preparing plasticizer with cta residue

Info

Publication number: WO2012119520A1
Application number: PCT/CN2012/071753
Authority: WO
Inventors: 黄珍华; 李凌
Original assignee: 福建天大化工有限公司
Priority date: 2011-03-08
Filing date: 2012-02-29
Publication date: 2012-09-13
Also published as: CN102206156B; CN102206156A

Abstract

Disclosed is a method for comprehensive utilization of CTA residues as a resource. In the present invention, the CTA residue is esterified into mixed phthalate esters, methylbenzoate, and benzoate, which are then separated, to obtain a heavy component of the mixed phthalate esters and a light component of the mixture of methylbenzoate and benzoate. The heavy component is a plasticizer that can be directly used, and the light component is transesterified to prepare a mixture of diethylene glycol (methyl)benzoate, which is also a well-performing plasticizer. In this way, the CTA residue is totally used for producing plasticizer products, achieving comprehensive resource utilization and achieving high economic and social benefits.

Description

Title: A Method for Making Plasticizers from CTA Residues

Technical field

[1] The present invention relates to the field of chemical industry, and in particular to a method for comprehensive utilization of CTA residue resources in a PTA production process.

Background technique

[2] Purified terephthalic acid (PTA) is one of the main raw materials for polyester chips and polyester fibers. Its domestic production capacity has exceeded 12 million tons per year, and there is still huge room for growth. The main by-product produced in the PTA production process is the CTA residue of the paraxylene chemical section, which accounts for about three-thousandths to five thousandths of the PTA production. The main component in the residue is mixed phthalic acid, methylbenzene. Conventional harmless treatment methods such as formic acid, benzoic acid, etc. are incineration and sewage treatment. Both of these methods have disadvantages such as inconvenient operation, energy consumption, large investment, and the risk of secondary pollution.

Summary of the invention

[3] An object of the present invention is to provide a method for comprehensive utilization of CTA residue resources to solve the above problems in the prior art.

[4] The technical solution provided by the present invention is as follows:

[5] The CTA residue generally contains p-dibenzoic acid, o-dibenzoic acid, m-dibenzoic acid, and methylbenzoic acid, and is a mixed benzoic acid. The method for comprehensive utilization of the present invention, the first CTA residue ester To form a mixed phthalic acid diester, methyl benzoate, benzoate, and then separate, the heavy component is mixed phthalic acid diester, the light component is methyl benzoate and benzoic acid a mixture of esters, the heavy component is used directly as a plasticizer, and the light component is then transesterified to form a mixture of diethylene glycol benzoate and diethylene glycol benzoate. This mixture is used as a plasticizer. .

[6] The foregoing method for comprehensive utilization of resources includes the following steps:

[7] The first step is to prepare a mixed organic isooctyl ester by reacting CTA residue with excess isooctanol;

[8] Step 2 Recovery of excess isooctyl alcohol in the crude ester;

[9] The third step separates isooctyl methylbenzoate and diisooctyl phthalate by distillation; [10] The fourth step is to refine the crude ester of diisooctyl phthalate;

[11] Step 5: Transesterification of (methyl) isooctyl benzoate to di(ethylene) benzoate;

[12] Step 6 (Methyl) Diethylene glycol benzoate refined.

[13] In a preferred embodiment of the present invention, the first step is: charging the CTA residue, the catalyst and the excess isooctanol into the reaction vessel to a temperature of 220-240 ° C, maintaining the reaction, and refluxing for 8-12 hours. The acid value was measured until the acid value was 0.5 mg KOH/g, and the reaction was terminated, and the obtained crude ester was subjected to the second step.

[14] In a preferred embodiment of the present invention, the second step recovers three processes of atmospheric pressure dealcoholization, vacuum de-alcoholization, and steam stripping and dealcoholization, and normal pressure dealcoholization means crude ester in a normal pressure state. The alcohol in the distillation is distilled off, and the de-alcoholization under vacuum means that the alcohol is distilled off under vacuum, and the stripping of the alcohol in the steam is to remove the trace amount of the alcohol in the crude ester after the de-alcoholization by vacuum. To meet the final product quality requirements.

[15] In a preferred embodiment of the present invention, the third step of the dealcoholized crude ester is subjected to vacuum distillation, first separating the lower boiling methyl isophthalate to the next transesterification step. Next, the mixed phthalic acid and isooctyl ester are distilled out, and the next step of the refining process is carried out; finally, a small amount of bottom slag is excluded from the autoclave, and the solid waste is harmlessly treated.

[16] In a preferred embodiment of the invention, the fourth step includes five processes of neutralization, water washing, stripping, vacuum drying, and pressure filtration.

[17] In a preferred embodiment of the present invention, the fifth step is carried out by adding an excess amount of diethylene glycol to the crude product of isobutyl (methyl)benzoate and performing transesterification under normal pressure.

[18] In a preferred embodiment of the invention, the refining of the sixth step of diethylene glycol (meth)benzoate comprises:

[19] (1), polycondensation: Due to the addition of excess diethylene glycol in the transesterification process, a large amount of monoester is inevitably present in the reactants, and the excess diethylene glycol is removed by the method of decompression and polycondensation. (methyl) crude diethylene glycol benzoate.

[20] ( 2 ), (methyl) benzoic acid diethylene glycol crude ester purification: The purification process is exactly the same as the fourth step crude ester purification process.

[21] Reactive [22] 1. Reaction formula of diisooctyl phthalate

[23] n H00C-R-C00H + 2n C8H170H Turn n HI 7C800C-R-C00C8H 17+2n H20

[24] where: C8H170H stands for diisooctyl alcohol

[25] H00C-R-C00H stands for phthalic acid (ie terephthalic acid, phthalic acid, isophthalic acid)

[26] 2. Reaction formula of isooctyl methylbenzoate

,, two _A

[27] n H00C-R-CH3+ n C8H170H Catalytic cutting n H17C800C-R-CH3+n H20

[28] where: H00C-R-CH3 represents methylbenzoic acid

[29] 3. The reaction formula of isooctyl benzoate:

[30] n R-C00H + n C8H170H iS n R-C00C8H17+ n H20

[31] where R-C00H represents benzoic acid

[32] 4. The reaction formula of preparing (methyl) benzoic acid diethylene glycol ester by transesterification:

[33] 2n R-C00C8H17+ n HO- R, -OH S R_C00R, +2n C8H170H

[34] wherein: R-C00H represents benzoic acid and methylbenzoic acid, and H0-R, _0H represents diethylene glycol.

[35] In each of the foregoing reactions, the catalyst used was tetrabutyl titanate.

[36] It can be seen from the above description that the CTA residue is first esterified into diisooctyl phthalate, isooctyl methyl benzoate, isooctyl benzoate, and then separated, and the heavy component is mixed benzene. Diisooctyl dicarboxylate, a light component of a mixture of isooctyl methylbenzoate and isooctyl benzoate, the former being a plasticizer that can be used directly, the latter being transesterified to form (methyl) a mixture of diethylene glycol benzoate, which is also a plasticizer with excellent properties. Thus, the CTA residue is used for the production of plasticizer products, achieving comprehensive utilization of resources, and having high economic benefits and society. benefit.

detailed description

[37] Embodiment 1

[38] First step Preparation of mixed organic isooctyl ester from CTA residue

[39] 4 kg of CTA residue, catalyst and isooctyl alcohol 9. lkg into the reactor to raise the temperature to 225 ° C, The reaction was incubated for about 10 hours, and the acid value was measured until the acid value was 0.5 mg koh/g, and the reaction was terminated, and the obtained crude ester was passed to the next step.

[40] Step 2 Alcohol

[41] The isooctyl alcohol in the crude ester is recovered and used in the production of the next batch. The recovery is divided into three processes of atmospheric pressure dealcoholization, vacuum de-alcoholization, and steam stripping and dealcoholation. Atmospheric de-alcoholization, the alcohol in the crude ester is distilled off under normal pressure. The de-alcoholization under vacuum means that the alcohol is distilled under vacuum, and the stripping of the alcohol is carried out by the partial pressure principle. The trace amount of alcohol in the crude ester is removed to the maximum extent to meet the final product quality requirements.

[42] Third step Distillation

[43] The crude ester after dealcoholation is subjected to vacuum distillation, and the lower boiling methyl isooctyl methacrylate is separated first, and the next transesterification step is carried out. Next, the mixed phthalic acid and isooctyl ester are distilled off, and the next purification step is carried out. Finally, a small amount of bottom slag is removed from the kettle and treated as a solid waste.

[44] Step 4 Crude ester refining

[45] This procedure is identical to the conventional crude ester refining process of diisooctyl phthalate (D0P) or diisooctyl terephthalate (D0TP), ie, neutralization, water washing, stripping, Five processes, such as vacuum drying and pressure filtration, are prior art and will not be described in detail.

[46] Step 5 Transesterification of (methyl) isooctyl benzoate

[47] In the crude mixture of isooctyl methylbenzoate and isooctyl benzoate, an excess of diethylene glycol (about 20% excess) is added, and transesterification is carried out under normal pressure for the purpose of (Methyl) isooctyl benzoate is converted into a low cost, excellent performance plasticizer (methyl) diethylene glycol benzoate. The endpoint of the reaction can be judged by calculating the amount of isooctanol that should be produced by transesterification.

[48] Step 6 Refinement of (methyl) diethylene glycol benzoate

[49] 1. Polycondensation

[50] Since an excessive amount of diethylene glycol is added in the transesterification step, a large amount of monoester is inevitably present in the reactant, and the present invention uses the method of decompression and polycondensation to exclude excess diethylene glycol to form (methyl). Crude ester of diethylene glycol benzoate.

[51] 2. Purification of (methyl) benzoic acid diethylene glycol crude ester

[52] This refining process is identical to the crude ester refining process of D0P and will not be described in detail here. The purified product is the di(ethylene) benzoic acid diethylene glycol ester of the product of the present invention.

[53] Example 2

[54] Basically the same as the first embodiment, except that in the first step: 4 kg of CTA residue, catalyst and isooctyl alcohol 9.45 kg were charged into the reaction vessel and heated to 240 ° C, the reaction was kept, and reflux was carried out. After about an hour, the acid value was measured until the acid value was 0.5 mg koh/g, and the reaction was terminated, and the obtained crude ester was passed to the next step.

[55] Example 3

[56] The same as the first embodiment, the difference is that in the first step: 4 kg of CTA residue, catalyst and isooctyl alcohol 9.8 kg into the reaction kettle to raise the temperature to 220 ° C, heat preservation reaction, reflux 12 After about an hour, the acid value was measured until the acid value was 0.5 mg koh/g, and the reaction was terminated, and the obtained crude ester was passed to the next step.

[57] Embodiment 4

[58] The same as the first embodiment, the difference is that in the first step: 4 kg of CTA residue, catalyst and isooctyl alcohol 10. lkg into the reactor to raise the temperature to 225 ° C, heat preservation reaction, reflux 10 After about an hour, the acid value was measured until the acid value was 0.5 mg koh/g, and the reaction was terminated, and the obtained crude ester was passed to the next step.

[59] Example 5

[60] The same as the first embodiment, except that in the first step: 4 kg of CTA residue, catalyst and isooctyl alcohol 10. 5 kg into the reaction kettle to raise the temperature to 225 ° C, heat preservation reaction, reflux 10 After about an hour, the acid value was measured until the acid value was 0.5 mg koh/g, and the reaction was terminated, and the obtained crude ester was passed to the next step.

[61] Example

[62]

CTA residue (dry amount) kg isooctyl alcohol kg catalyst accounted for CTA residue mass ratio Example 1 4 9. 1 2/1000 Example 2 4 9. 45 2/1000 Example 3 4 9. 8 2/1000 Example 4 4 10. 1 2/1000 Example 5 4 10. 5 2/1000

[63] Results:

[64] 1. The CTA residue and the isooctanoate reaction are completed within 16 hours;

[65] 2. The exchange of (methyl) isooctyl benzoate with diethylene glycol is completed within 8 hours, and the transesterification product containing mono- 酉ί completes polycondensation in 4 hours to form the final product (methyl) benzene. Diethylene glycol formate.

[66] 3. Two plasticizer products after esterification, transesterification, refining, etc., namely diisooctyl phthalate (project product 1) and mixed (methyl) benzoic acid diethylene glycol The product quality indicators of alcohol esters (project 2) meet or exceed the products of conventional plasticizer DOP

Product quality index list

The insubstantial modification of the present invention by this concept is intended to be an infringement of the scope of the present invention.

Industrial applicability

[70] From the above description, the present invention first esterifies the CTA residue into a mixed phthalic acid diester, a methyl benzoate, a benzoate, and then separates it, and the heavy component is a mixed phthalic acid. Octyl ester, a light component of a mixture of isooctyl methylbenzoate and isooctyl benzoate, the former being a plasticizer that can be used directly, the latter being transesterified to produce (meth)benzoic acid diethyl A mixture of glycol esters, the latter mixture is also an excellent plasticizer.

Claims

Claim

[Claim 1] A method for preparing a plasticizer from a CTA residue, first esterifying a CTA residue into a mixed phthalate, a methyl benzoate, a benzoate, and then separating the heavy component Mixed phthalic acid diester, light component is a mixture of methyl benzoate and benzoate, heavy component is used directly as plasticizer, light component is then transesterified to produce methyl benzoic acid A mixture of an alcohol ester and diethylene glycol benzoate, this mixture being used as a plasticizer.

[Claim 2] A method of producing a plasticizer for a CTA residue according to claim 1, comprising: the following steps:

The first step of reacting the CTA residue with an excess of isooctyl alcohol to prepare a mixed organic isooctyl ester; the second step recovering the excess isooctyl alcohol in the crude ester;

The third step separates isooctyl methylbenzoate, isooctyl benzoate and diisooctyl phthalate by distillation;

The fourth step is to distill the crude diisooctyl phthalate ester;

Step 5: (Methyl) isooctyl benzoate is transesterified to (methyl) benzoic acid diethylene glycol 酉 ί

(Methyl) diethylene glycol benzoate refined.

[Claim 3] A method for preparing a plasticizer for a CTA residue according to claim 2, wherein: the first step is: charging the CTA residue, the catalyst, and the excess isooctyl alcohol into the reaction vessel to 220 The temperature is -240 ° C, the reaction is incubated for 8-12 hours, the acid value is measured until the acid value is 0. 5 mg ΚΟΗ / g, the reaction is terminated, and the crude ester obtained is introduced.

[Claim 4] The method for comprehensive utilization of CTA residue according to claim 2, wherein: the second step comprises three processes of atmospheric pressure dealcoholation, vacuum de-alcoholization, and steam stripping and dealcoholation, often The alcohol is distilled off under normal pressure, and the alcohol in the crude ester is distilled off under vacuum. The de-alcohol is distilled under vacuum to remove alcohol. The steam stripping and de-alcoholization is the crude dehydration after decompression by the principle of partial pressure. The trace amount of alcohol in the ester is removed as much as possible.

[Claim 5] A method for preparing a plasticizer for a CTA residue according to claim 2, wherein in the third step, the crude ester after dealcoholation is subjected to vacuum distillation, and the boiling point is lower first. The isooctyl methyl benzoate is separated, and the next transesterification step is carried out; the mixed diisooctyl phthalate is distilled out, and the next purification step is carried out; finally, a small amount of bottom slag is excluded from the autoclave as a solid. Harmless disposal of waste.

[Claim 6] A method for producing a plasticizer for a CTA residue according to claim 2, wherein: the fourth step comprises five processes of neutralization, water washing, stripping, vacuum drying, and pressure filtration.

[Claim 7] A method for preparing a plasticizer for a CTA residue according to claim 2, wherein: in the fifth step, an excessive amount of dibasic is added to the crude product of (meth)benzoic acid isooctyl ester. The diol is subjected to transesterification under normal pressure.

[Claim 8] A method of producing a plasticizer for a CTA residue according to claim 2, wherein: the sixth step of refining the diethylene glycol benzoate comprises:

(1) Excluding excess diethylene glycol by means of reduced compression polymerization to produce (ethylene) benzoic acid diethylene glycol coarse 酉

( 2 ), (methyl) benzoic acid diethylene glycol crude ester purification: the purification process and the fourth [Claim 9] A method of producing a plasticizer for a CTA residue according to any one of claims 2 to 8, wherein the catalyst used is tetrabutyl titanate.