CN109776313B - Mixed ester derived from PTA residue and synthesis method thereof - Google Patents

Abstract

The present application relates to a process for the synthesis of mixed esters derived from PTA residues comprising the steps of: s1: reacting the PTA residue, diethylene glycol, isooctanol, catalyst, and mineral acid at a first temperature for a first predetermined time period to obtain a first reaction mixture; s2: maintaining the first reaction mixture at a second temperature for a second predetermined period of time to obtain the mixed ester derived from the PTA residue. The present application also relates to a mixed ester prepared using the method as above. The process described herein enables the complete recovery of PTA residues without the production of any waste acid or waste water. The method creatively uses the inorganic acid in the process of synthesizing the mixed ester by utilizing the PTA residue, the inorganic acid is beneficial to recovering the heavy metal catalyst in the PTA residue and can be simultaneously used as a selective catalyst and a reducing agent, and the filtration time in the process of synthesizing the mixed ester is shortened.

Description

Mixed ester derived from PTA residue and synthesis method thereof

Technical Field

The application relates to the technical field of organic synthesis and chemical waste recycling. In particular, the present application relates to a mixed ester derived from PTA residues and a process for the synthesis thereof.

Background

As specified in the group Standard "T/SPUIA 000001-2018" issued by the polyurethane industry Association in Shanghai, purified Terephthalic Acid (PTA) residue (residual quenching in pure terephthalic acid contamination) refers to a residue produced in both oxidation and purification processes for producing Purified Terephthalic Acid (PTA), and has terephthalic acid, p-toluic acid, isophthalic acid, benzoic acid, and the like as main components. 90% of these components in the PTA residue have recycling value.

China is a large country for PTA production, producing at least 4000 million tons of PTA per year, producing about 5 kilograms of PTA residue per ton of PTA produced, and producing at least 20 million tons of PTA residue per year. Therefore, the task of recycling the PTA residues is very difficult. The chemical method for recycling PTA residues at present mainly comprises the steps of preparing a plasticizer by an esterification method, synthesizing a methyl ester compound by esterification of methanol, preparing unsaturated resin by esterification of the methyl ester compound and ethylene glycol, preparing activated carbon by utilizing the PTA residues and the like.

In the methods, the PTA residues are used as the polybasic acid raw material to synthesize the environment-friendly plasticizer, so that the method has wide application prospect. However, in the PTA production process, heavy metals such as cobalt and manganese are used as catalysts, and these heavy metal catalysts also remain in the PTA residue, which brings certain obstacles to recycling of the PTA residue.

For this reason, there is a continuing need in the art to develop a mixed ester derived from PTA residues and a method for synthesizing the same that can reduce or even eliminate the effect of heavy metal catalysts.

Disclosure of Invention

The PTA residue contains residual heavy metal catalyst such as cobalt or manganese, etc. On the one hand, the heavy metal catalysts are expensive, but cannot be effectively recycled due to the inclusion in the PTA residues, so that precious resources are wasted. On the other hand, when other polymers having economic value are synthesized by using PTA residues, these heavy metal catalysts or their ions easily form metal soaps with organic acids, which are not easily hydrated, and this makes the subsequent filtration process more difficult, resulting in too long filtration time and significantly shortened service life of the filtration equipment. Furthermore, in the process of producing PTA, it is often necessary to wash the piping with a strong base such as sodium hydroxide in order to descale the piping. When the PTA residue is used for synthesizing polymers, cations in strong alkali can form metal soaps, so that the difficulty of filtration is increased

The present application aims to provide a method for synthesizing PTA-derived residues, which can reduce or even eliminate the effect of heavy metal catalysts, thereby solving the above technical problems in the prior art. Specifically, the process of the present application pioneers the addition of mineral acids as additives in the synthesis of mixed esters using PTA residues. The inorganic acid can convert various water-insoluble metal soaps in the PTA residue into inorganic acid salts which are easily soluble in water or a reaction system, which unexpectedly shortens the time consumed by the synthesized mixed ester in the subsequent filtration and can simultaneously recover the precious heavy metals.

It is also an object of the present application to provide a mixed ester derived from PTA residues prepared using the above process.

In order to achieve the above object, the present application provides the following technical solutions.

In a first aspect, the present application provides a process for the synthesis of mixed esters derived from PTA residues, characterized in that said process comprises the steps of:

s1: reacting the PTA residue, diethylene glycol, isooctanol, catalyst, and mineral acid at a first temperature for a first predetermined time period to obtain a first reaction mixture;

s2: maintaining the first reaction mixture at a second temperature for a second predetermined period of time to obtain the mixed ester derived from the PTA residue.

In one embodiment of the first aspect, the first temperature is from 120 ℃ to 180 ℃;

and/or the second temperature is 220-240 ℃.

In one embodiment of the first aspect, the first predetermined period of time is 5-6 hours;

and/or the second predetermined period of time is 2-3 hours.

In an embodiment of the first aspect, after step S2, the method further comprises the steps of:

s3: the mixed ester obtained in step S2 is subjected to vacuum dehydration at a temperature of 190 to 240 ℃ until the acid value of the mixed ester reaches a predetermined acid value.

In an embodiment of the first aspect, after step S2, the method further comprises the steps of:

s4: the mixed ester obtained in step S2 is steam stripped at a temperature of 175-185 ℃.

In one embodiment of the first aspect, the inorganic acid comprises one or more of phosphoric acid, phosphorous acid, hypophosphorous acid or boric acid.

In one embodiment of the first aspect, the catalyst comprises one or more of tetrabutyl titanate, zinc acetate, or dibutyltin dilaurate.

In one embodiment of the first aspect, the total amount of diethylene glycol and isooctanol is in excess relative to the total amount of acid and inorganic acid in the PTA residue.

In a second aspect, the present application provides a mixed ester derived from PTA residues prepared by the process as described in the first aspect.

In a third aspect, the present application provides the use of a mixed ester derived from PTA residues as described in the second aspect as plasticizer in the preparation of polymers.

Compared with the prior art, the method has the advantages that the PTA residue can be completely recycled by the method, and no waste acid or waste water is generated. The inorganic acid is used in the process of synthesizing the mixed ester by utilizing the PTA residue for the first time, is beneficial to recovering the heavy metal catalyst in the PTA residue and can be simultaneously used as a selective catalyst and a reducing agent, so that the filtration time in the process of synthesizing the mixed ester is shortened, and the ester content in the prepared mixed ester is more than 97 percent according to GB/T1665-2008.

In addition, when the mixed esters described herein are used as plasticizers, the plasticizing temperature can be reduced from 180 ℃ to 168 ℃. The mixed esters described herein have a high flash point and can be used in amounts reduced by 20% to achieve a plasticizing effect comparable to conventional plasticizers such as DOTP, calcium carbonate. In addition, the mixed ester has high adaptability and still has strong acceleration effect on polymer systems with high impurity content. In addition, the plasticizers described herein are environmentally friendly and inexpensive because they can be prepared from industrial waste PTA residues.

Detailed Description

Unless otherwise indicated, implicit from the context, or customary in the art, all parts and percentages herein are based on weight and the testing and characterization methods used are in step with the filing date of the present application. Where applicable, the contents of any patent, patent application, or publication referred to in this application are incorporated herein by reference in their entirety and their equivalent family patents are also incorporated by reference, especially as they disclose definitions relating to synthetic techniques, products and process designs, polymers, comonomers, initiators or catalysts, and the like, in the art. To the extent that a definition of a particular term disclosed in the prior art is inconsistent with any definitions provided herein, the definition of the term provided herein controls.

The numerical ranges in this application are approximations, and thus may include values outside of the ranges unless otherwise specified. A numerical range includes all numbers from the lower value to the upper value, in increments of 1 unit, provided that there is a separation of at least 2 units between any lower value and any higher value. For example, if a compositional, physical, or other property (e.g., molecular weight, melt index, etc.) is recited as 100 to 1000, it is intended that all individual values, e.g., 100, 101,102, etc., and all subranges, e.g., 100 to 166,155 to 170,198 to 200, etc., are explicitly recited. For ranges containing values less than 1 or fractions greater than 1 (e.g., 1.1,1.5, etc.), then 1 unit is considered to be 0.0001,0.001,0.01 or 0.1, as appropriate. For ranges containing single digit numbers less than 10 (e.g., 1 to 5), 1 unit is typically considered 0.1. These are merely specific examples of what is intended to be expressed and all possible combinations of numerical values between the lowest value and the highest value enumerated are to be considered to be expressly stated in this application. The numerical ranges within this application provide, among other things, the amount of each comonomer in the acrylate copolymer, the amount of each component in the photoresist composition, the temperature at which the acrylate is synthesized, and the various characteristics and properties of these components.

When used with respect to a chemical compound, the singular includes all isomeric forms and vice versa (e.g., "hexane" includes all isomers of hexane, individually or collectively) unless explicitly stated otherwise. In addition, unless explicitly stated otherwise, the use of the terms "a", "an" or "the" are intended to include the plural forms thereof.

The terms "comprising," "including," "having," and derivatives thereof do not exclude the presence of any other component, step or procedure, and are not relevant to whether such other component, step or procedure is disclosed herein. To the extent that any doubt is eliminated, all compositions herein containing, including, or having the term "comprise" may contain any additional additive, adjuvant, or compound, unless expressly stated otherwise. Rather, the term "consisting essentially of … …" excludes any other components, steps or processes except those necessary for operability outside the scope of any such term as hereinafter recited. The term "consisting of … …" does not include any components, steps or processes not specifically described or listed. Unless explicitly stated otherwise, the term "or" refers to the listed individual members or any combination thereof.

In one embodiment, the present application provides a process for synthesizing mixed esters derived from PTA residues, characterized in that the process comprises the steps of:

s1: reacting the PTA residue, diethylene glycol, isooctanol, catalyst, and mineral acid at a first temperature for a first predetermined time period to obtain a first reaction mixture;

s2: maintaining the first reaction mixture at a second temperature for a second predetermined period of time to obtain the mixed ester derived from the PTA residue.

In one embodiment, when the catalyst is unstable under the reaction conditions in step S1, the catalyst may be added in step S2.

In one embodiment, the first temperature is 120 ℃ to 180 ℃. In a preferred embodiment, the first temperature may be 120 ℃, 125 ℃, 130 ℃, 135 ℃, 150 ℃, 160 ℃, 170 ℃, 175 ℃ or 180 ℃.

In one embodiment, the second temperature is 220-240 ℃. In a preferred embodiment, the second temperature may be 220 ℃, 225 ℃, 230 ℃, 235 ℃ or 240 ℃.

In one embodiment, the first predetermined period of time is 5-6 hours. In a preferred embodiment, the first predetermined period of time may be 5 hours, 5.5 hours, or 6 hours.

In one embodiment, the second predetermined period of time is 2-3 hours. In a preferred embodiment, the second predetermined period of time may be 2 hours, 2.5 hours, or 3 hours.

In one embodiment, the purified terephthalic acid residue is a PTA residue from ashore petrochemical. Although the main concepts and spirit of the present application are described in the following examples by way of examples of PTA residues from ashore petrochemical, it will be understood by those skilled in the art that the process of the present application is equally applicable to other PTA residues of different compositions.

The process of the present application pioneers the addition of mineral acids as additives in the synthesis of mixed esters using PTA residues. The inorganic acid can convert various water-insoluble metal soaps in the PTA residue into inorganic acid salts which are easily soluble in water or a reaction system, which unexpectedly shortens the time consumed by the synthesized mixed ester in the subsequent filtration and can simultaneously recover the precious heavy metals. Unreacted acid can react with isooctanol to form the corresponding ester without producing waste acid or waste water.

In one embodiment, the mineral acid may act as a catalyst to selectively accelerate the reaction between the polyacid and the monohydric alcohol in the particular reaction system described herein.

In one embodiment, the inorganic acid comprises one or more of phosphoric acid, phosphorous acid, hypophosphorous acid or boric acid.

In one embodiment, the total amount of diethylene glycol and isooctanol is in excess relative to the total amount of acid and mineral acid in the PTA residue. This is beneficial to both increase the conversion of acid in the PTA residue and to convert excess mineral acid to the corresponding ester.

In one embodiment, the catalyst comprises one or more of tetrabutyl titanate, zinc acetate, or dibutyltin dilaurate.

In a specific embodiment, after step S2, the method further comprises the steps of:

s3: the mixed ester obtained in step S2 is subjected to vacuum dehydration at a temperature of 190 to 240 ℃ until the acid value of the mixed ester reaches a predetermined acid value. In one embodiment, the predetermined acid value is less than or equal to 1.0mgKOH/g.

In one embodiment, the vacuum dewatering is performed at a vacuum level of greater than or equal to-0.02 MPa. As will be understood by those skilled in the art, the term "a vacuum of greater than or equal to-0.02 MPa" means that the vacuum of the reaction vessel during vacuum dehydration is-0.02 MPa, -0.03MPa … … -0.1MPa, etc.

In a specific embodiment, after step S2, the method further comprises the steps of:

s4: the mixed ester obtained in step S2 is steam stripped at a temperature of 175-185 ℃.

In one embodiment, the ester composition is steam stripped at a steam pressure of 0.1MPa. In one embodiment, steam stripping is performed primarily for the purpose of removing unreacted isooctanol.

In a second aspect, the present application provides a mixed ester derived from PTA residues produced by the process of the first aspect.

In a third aspect, the present application provides the use of a mixed ester derived from PTA residues as described in the second aspect as plasticizer in the preparation of polymers.

Any combination of the above preferred conditions, while meeting the general knowledge in the art, will result in a preferred embodiment of the invention.

Examples

The technical solutions of the present application will be clearly and completely described below with reference to the embodiments of the present application. The reagents and raw materials used are commercially available unless otherwise specified.

Preparation examples

Example 1

The experimental procedure of this example is as follows.

First, 2000kg of isooctanol, 4100kg of PTA residue (Shanghai petrochemical), 330kg of diethylene glycol and 50kg of phosphoric acid were charged into a reaction vessel. Dehydration was carried out at a temperature of 120 ℃ for 5 hours to obtain a first reaction mixture.

Then, 1500kg of isooctanol and 6.5kg of tetrabutyltitanate were further added to the first reaction mixture and reacted at a temperature of 220 ℃ for 2 hours. After the reaction, dehydration was carried out under vacuum at-0.02 MPa until the acid value of the resulting mixed ester was 1.0mgKOH/g or less. After the acid value reaches the standard, the temperature of the reaction system is reducedRemoving excess alcohol by steam stripping at 180 deg.C until the flash point of the mixed ester is 190 deg.C or higher and the density at 20 deg.C is 0.982-0.988g/cm ³ . The steam stripping pressure is 0.2-0.4MPa. After the steam stripping was completed, the temperature was reduced to 150 ℃ or below, and the mixture was filtered for 2 hours at a flux of 5000 kg/hour using a CT-10 type filter having a filtration area of 10 square meters, and the flow rate of the filtrate discharge pump was 12 cubic meters per hour, and the viscous liquid obtained was the mixed ester according to example 1.

The mixed ester according to example 1 was tested to have the following properties: the appearance is dark brown, determined according to GB/T1664-1995; the density at 20 ℃ is 0.988g/cm ³ Measured according to GB/T1884-2000 (2004); the acid value is 1.0mgKOH/g, and the determination is carried out according to GB/T1668-2008; the water content is 0.1 percent, and the determination is carried out according to GB/T260-2016; the flash point measured by a closed cup method is 197 ℃ and is measured according to GB/T261-2008; and an ester content of 97% determined according to GB/T1665-2008.

Example 2

The experimental procedure of this example is as follows.

First, 2000kg of isooctanol, 4100kg of PTA residue (Shanghai petrochemical), 330kg of diethylene glycol, 25kg of zinc acetate and 60kg of boric acid were charged into a reaction vessel. Dehydration was carried out at a temperature of 120 ℃ for 5 hours to obtain a first reaction mixture.

Then, 1500kg of isooctanol was further added to the first reaction mixture and reacted at a temperature of 220 ℃ for 2 hours. After the reaction, dehydration was carried out under vacuum at-0.02 MPa until the acid value of the resulting mixed ester was 1.0mgKOH/g or less. After the acid value reaches the standard, the temperature of the reaction system is reduced to 180 ℃, excessive alcohol is removed by steam stripping until the flash point of the obtained mixed ester is more than or equal to 190 ℃, and the density at 20 ℃ is 0.982-0.988g/cm ³ . The steam stripping pressure is 0.2-0.4MPa. After the steam stripping was completed, the temperature was reduced to 150 ℃ or below, and the mixture was filtered for 2 hours at a flux of 6000 kg/hour using a CT-10 type filter having a filter area of 10 square meters, and the flow rate of the filtrate discharge pump was 12 cubic meters per hour, and the viscous liquid obtained was the mixed ester according to example 2.

The performance parameters of the mixed ester according to example 2 were tested to be similar to those of the mixed ester of example 1.

Example 3

The experimental procedure of this example is as follows.

First, 2000kg of isooctanol, 4100kg of PTA residue (Shanghai petrochemical), 330kg of diethylene glycol, 5.5kg of dibutyltin dilaurate and 70kg of phosphorous acid were charged into a reaction vessel. Dehydration was carried out at a temperature of 120 ℃ for 5 hours to obtain a first reaction mixture.

Then, 1500kg of isooctanol was further added to the first reaction mixture and reacted at a temperature of 220 ℃ for 2 hours. After the reaction, dehydration was carried out under vacuum at-0.02 MPa until the acid value of the resulting mixed ester was 1.0mgKOH/g or less. After the acid value reaches the standard, the temperature of the reaction system is reduced to 180 ℃, excessive alcohol is removed by steam stripping until the flash point of the obtained mixed ester is more than or equal to 190 ℃, and the density at 20 ℃ is 0.982-0.988g/cm ³ . The steam stripping pressure is 0.2-0.4MPa. After the steam stripping was completed, the temperature was reduced to below 150 ℃ and filtered for 2 hours at a flux of 5000 kg/hour using a CT-10 type filter with a filter area of 10 square meters, and the flow rate of the filtrate discharge pump was 12 cubic meters per hour, and the viscous liquid obtained was the mixed ester according to example 3.

The performance parameters of the mixed ester according to example 3 were tested to be similar to those of the mixed ester of example 1.

Example 4

The experimental procedure of this example is as follows.

First, 2000kg of isooctanol, 4100kg of PTA residue (Shanghai petrochemical), 330kg of diethylene glycol and 50kg of hypophosphorous acid were charged into a reaction vessel. Dehydration was carried out at a temperature of 120 ℃ for 5 hours to obtain a first reaction mixture.

Then, 1500kg of isooctanol and 6.5kg of tetrabutyltitanate were further added to the first reaction mixture and reacted at a temperature of 220 ℃ for 2 hours. After the reaction, dehydration was carried out under vacuum at-0.02 MPa until the acid value of the resulting mixed ester was 1.0mgKOH/g or less. After the acid value reaches the standard, the temperature of the reaction system is reduced to 180 ℃, and the reaction system is stripped by steam to removeRemoving excess alcohol until the flash point of the mixed ester is 190 deg.C or higher and the density at 20 deg.C is 0.982-0.988g/cm ³ . The steam stripping pressure is 0.2-0.4MPa. After steam stripping is finished, the temperature is reduced to below 150 ℃, the mixture is filtered for 2 hours by using a CT-10 type filter with the filtering area of 10 square meters at the flux of 6000 kg/hour, the flow rate of a filtrate discharging pump is 12 cubic meters per hour, and the obtained viscous liquid is the mixed ester according to the embodiment 4.

The performance parameters of the mixed ester according to example 4 were tested to be similar to those of the mixed ester of example 1.

In the examples described above, the heavy metals may be recovered from the mixed esters by conventional means. For example, sodium carbonate is added to the mixed ester, followed by separation.

The embodiments described above are intended to facilitate the understanding and appreciation of the application by those skilled in the art. It will be readily apparent to those skilled in the art that various modifications to these embodiments may be made, and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present application is not limited to the embodiments herein, and those skilled in the art who have the benefit of this disclosure will appreciate that many modifications and variations are possible within the scope of the present application without departing from the scope and spirit of the present application.

Claims (3)

1. A process for the synthesis of mixed esters derived from PTA residues, comprising the steps of:

s1: reacting the PTA residue, diethylene glycol, isooctanol, catalyst, and mineral acid at a first temperature for a first predetermined period of time to obtain a first reaction mixture;

s2: maintaining the first reaction mixture at a second temperature for a second predetermined period of time to obtain the mixed ester derived from the PTA residue;

the inorganic acid comprises one or more of phosphoric acid, phosphorous acid, hypophosphorous acid or boric acid;

the second predetermined period of time is 2 hours;

the first temperature is 120 ℃;

the second temperature is 220 ℃;

the first predetermined period of time is 5 hours;

the catalyst comprises one or more of tetrabutyl titanate, zinc acetate or dibutyltin dilaurate;

the total amount of diethylene glycol and isooctanol is in excess, on a molar basis, relative to the total amount of acid and inorganic acid in the PTA residue.

2. The process for synthesizing mixed esters derived from PTA residues of claim 1, wherein after step S2, the process further comprises the steps of:

s3: the mixed ester obtained in step S2 is subjected to vacuum dehydration at a temperature of 190 to 240 ℃ until the acid value of the mixed ester reaches a predetermined acid value.

3. The process for synthesizing mixed esters derived from PTA residues of claim 1, wherein after step S2, the process further comprises the steps of:

s4: the mixed ester obtained in step S2 is steam stripped at a temperature of 175-185 ℃.