CN111704713B

CN111704713B - Titanium catalyst for polyester synthesis and preparation method thereof

Info

Publication number: CN111704713B
Application number: CN201910210911.XA
Authority: CN
Inventors: 蒋新
Original assignee: Zhejiang University ZJU
Current assignee: Zhejiang University ZJU
Priority date: 2019-03-18
Filing date: 2019-03-18
Publication date: 2022-03-29
Anticipated expiration: 2039-03-18
Also published as: CN111704713A

Abstract

The invention relates to a titanium catalyst for polyester synthesis and a preparation method thereof, and the prepared catalyst suspension can be directly used for polyester synthesis. The preparation method directly prepares the supported titanium heterogeneous catalyst in one of polyester monomers, such as ethylene glycol, butanediol and the like. The catalyst prepared by the method can be directly used in the catalytic process of polyester reaction without separation. The preparation process is green and environment-friendly, has no emission, and the catalyst has the characteristics of high dispersibility, high activity, simple operation and lower cost.

Description

Titanium catalyst for polyester synthesis and preparation method thereof

Technical Field

The invention belongs to the field of catalyst preparation, and relates to a Ti catalyst for polyester and a preparation method thereof.

Background

The most widely used catalyst in the polyester industry is the Sb-based catalyst. However, since the Sb compound itself has a certain toxicity, its use is limited, and development of a novel catalyst is urgently required. Therefore, various large polyester companies at home and abroad research novel catalysts capable of replacing Sb series. In this aspect, the Ti-based catalyst has the characteristics of high catalytic activity and low dosage, and is the most studied polyester catalyst and the most promising polyester catalyst for industrial application.

In the study of Ti-based catalysts, inorganic salts (e.g., potassium fluorotitanate, potassium titanyl oxalate, etc.) or organic esters (e.g., tetrabutyl titanate, etc.) of Ti have been used in the early days. The catalysts have good dispersibility in a polyester reaction system, and have the characteristics of small using amount, high catalytic reaction speed and capability of shortening reaction time. However, since the activity of Ti in these catalysts is not controlled, the polycondensation process causes a large number of side reactions, which severely deteriorates the quality of the polyester, as evidenced by severe yellowing of the hue, increased carboxyl end groups, increased diethylene glycol content, and decreased melting point.

At present, two methods are mainly used for regulating and controlling the activity of Ti-series catalysts, one method is to synthesize Ti-containing complexes with complex molecular structures, and the other method is to use the regulation and control means of classical supported catalysts for reference. The first method is to obtain an organic complex of Ti, which is difficult to effectively reduce the cost due to its complicated structure and long preparation path. The second catalyst is heterogeneous catalyst, which has poor dispersivity and is easy to agglomerate. Because the polyester reaction is a high-viscosity reaction system, the transfer rate is low, the dispersity of the heterogeneous catalyst is poor, and the activity of the heterogeneous catalyst is seriously influenced.

Disclosure of Invention

The technical problem to be solved by the invention is to provide a preparation method of a titanium catalyst for polyester synthesis, and the prepared catalyst does not need to be separated, and the obtained catalyst suspension can be directly used for polyester catalytic reaction. Therefore, the invention adopts the following technical scheme:

a process for preparing the Ti-series catalyst used for synthesizing polyester features that the reaction system for preparing catalyst is mainly composed of polyol, and the catalyst carrier, titanate compound and less solvent are added to the polyol system for reaction to obtain the catalyst suspension.

The reaction temperature in the preparation process of the catalyst is preferably-10-120 ℃, and more preferably 10-60 ℃.

The reaction time in the catalyst preparation process is preferably 0.5 to 20 hours, more preferably 2 to 8 hours.

The titanate compounds of the present invention can be selected from the group consisting of but not limited to ethyl titanate, propyl titanate, and butyl titanate.

In a preferred embodiment of the present invention, the titanate compound is added to the reaction system in the form of an alcoholic solution of titanate compound, which may be a monohydric alcohol solution, a polyhydric alcohol solution, or a mixed alcoholic solution.

The polyol is a single polyol or a mixed polyol, and in a preferred embodiment of the invention, the polyol is selected from the range including ethylene glycol, propylene glycol, glycerol, butylene glycol and isoprene glycol.

In a preferred embodiment of the present invention, the titanate-based compound is added in an amount of 0.1 to 10 times by mass as much as the catalyst carrier.

In a preferred embodiment of the invention, the minor amount of other solvent is added in an amount of 0.1 to 10 volume percent based on the amount of polyol.

In a preferred embodiment of the invention, the minor amount of other solvent is one or more of water, monohydric lower alcohol.

In a preferred embodiment of the invention, the catalyst support is selected from the group consisting of silica, alumina, zeolite, diatomaceous earth, and montmorillonite.

The invention provides a preparation method of a titanium catalyst which directly loads Ti active components on the surface of a carrier material with high dispersibility in a polyalcohol solution. The titanium catalyst for polyester synthesis obtained by the preparation method is a catalyst suspension, the catalyst suspension can be directly applied to polyester catalytic reaction without separation, and the polyester is obtained by heating reaction under the conventional reaction condition. Fundamentally avoids catalyst particle agglomeration caused by the separation process, effectively solves the problem of catalyst dispersibility, does not need to use extra solvent, basically has no three-waste discharge in the preparation process, and is a green and environment-friendly process.

Detailed description of the invention

The method for preparing the catalyst and the use of the catalyst in the polyester reaction according to the present invention are described in further detail with reference to the following specific examples, which should not be construed as limiting the scope of the present invention, and the non-essential modifications and adaptations of the present invention by those skilled in the art according to the present invention as described above will still fall within the scope of the present invention.

Example 1

500ml of ethylene glycol was added to the stirred tank and the stirring was started. 4g of silica (AEROSIL 200 from Degussa) was weighed into a reaction vessel; 8mL of deionized water was weighed and added to the reaction kettle. And adding 20g of butyl titanate into 100mL of ethylene glycol, and uniformly stirring to prepare the ethylene glycol solution of the butyl titanate. A solution of butyl titanate in ethylene glycol was added dropwise to the reaction kettle at a rate of 10mL/min with stirring at 20 ℃. After the addition was complete, the reaction temperature was gradually increased at a rate of 10 ℃ per hour until 80 ℃. And after reacting for 1h, cooling to stop the reaction to obtain a catalyst suspension.

300mL of ethylene glycol was added to the polymerization kettle, followed by 0.5mL of the catalyst suspension. After dispersing uniformly, 400g of terephthalic acid is added and then stirred uniformly. Gradually heating to boil a little liquid in the bottle at normal pressure, controlling the temperature of the kettle and the top temperature well, keeping the glycol in the system, and keeping the distillate only containing water. When the water is not distilled off, the temperature is gradually increased. And (5) connecting a vacuum system, and gradually increasing the vacuum degree of the system. And continuously reacting for 2 hours under the high vacuum condition to obtain the polyester. The product intrinsic viscosity was 0.61dl/g, the L value was 83.2, and the b value was 7.4.

Example 2

500ml of ethylene glycol was added to the stirred tank and the stirring was started. Weighing 3g of zeolite raw powder, roasting, and adding into a reaction kettle; 3mL of deionized water was weighed and added to the reaction kettle. And adding 10g of butyl titanate into 100mL of ethylene glycol, and uniformly stirring to prepare the ethylene glycol solution of the butyl titanate. A solution of butyl titanate in ethylene glycol was added dropwise to the reaction kettle at a rate of 10mL/min with stirring at 40 ℃. After the addition was complete, the reaction temperature was gradually increased at a rate of 10 ℃ per hour until 90 ℃. And after reacting for 1h, cooling to stop the reaction to obtain a catalyst suspension.

300mL of ethylene glycol was added to the polymerization kettle, followed by 0.8mL of catalyst suspension. After dispersing uniformly, 400g of terephthalic acid is added and then stirred uniformly. Gradually heating to boil a little liquid in the bottle at normal pressure, controlling the temperature of the kettle and the top temperature well, keeping the glycol in the system, and keeping the distillate only containing water. When the water is not distilled off, the temperature is gradually increased. And (5) connecting a vacuum system, and gradually increasing the vacuum degree of the system. And continuously reacting for 3 hours under the high vacuum condition to obtain the polyester. The product intrinsic viscosity was 0.64dl/g, the L value was 80.4, and the b value was 6.2.

Example 3

500ml of ethylene glycol was added to the stirred tank and the stirring was started. 5g of silica (AEROSIL 200 from Degussa) was weighed into a reaction vessel; 4mL of deionized water was weighed and added to the reaction kettle. And adding 15g of butyl titanate into 200mL of ethylene glycol, and uniformly stirring to prepare the ethylene glycol solution of the ethyl titanate. A solution of ethyl titanate in ethylene glycol was added dropwise to the reaction kettle at a rate of 10mL/min with stirring in an ice bath. After the addition was complete, the reaction temperature was gradually increased at a rate of 20 ℃/h until 100 ℃. And after reacting for 1h, cooling to stop the reaction to obtain a catalyst suspension.

300mL of ethylene glycol was added to the polymerization kettle, followed by 0.2mL of catalyst suspension. After dispersing uniformly, 400g of terephthalic acid is added and then stirred uniformly. Gradually heating to boil a little liquid in the bottle at normal pressure, controlling the temperature of the kettle and the top temperature well, keeping the glycol in the system, and keeping the distillate only containing water. When the water is not distilled off, the temperature is gradually increased. And (5) connecting a vacuum system, and gradually increasing the vacuum degree of the system. And continuously reacting for 3 hours under the high vacuum condition to obtain the polyester. The product intrinsic viscosity was 0.66dl/g, the L value was 88.3, and the b value was 4.8.

Example 4

500ml of butanediol were added to the stirred tank and the stirring was started. 5g of silica (AEROSIL 200 from Degussa) are weighed into a reaction vessel, followed by 25g of butyl titanate; and adding 10mL of deionized water into another 100mL of butanediol, and uniformly stirring to prepare a water-butanediol solution. The water-butanediol solution was added dropwise to the reaction kettle at a rate of 10mL/min with stirring at 20 ℃. After the addition was complete, the reaction temperature was gradually increased at a rate of 10 ℃ per hour until 60 ℃. And after reacting for 3 hours, cooling to stop the reaction to obtain a catalyst suspension.

300mL of butanediol was added to the polymerization kettle, followed by 0.5mL of the catalyst suspension. After dispersing uniformly, 300g of terephthalic acid is added and then stirred uniformly. Gradually heating up to a state that a small amount of liquid in the bottle begins to boil under normal pressure, controlling the temperature of the kettle and the top temperature well, and keeping that only water is contained in distillate. When the water is not distilled off, the temperature is gradually increased. And (5) connecting a vacuum system, and gradually increasing the vacuum degree of the system. The reaction is continued for 3 hours under the high vacuum condition to obtain the PBT polyester, and the intrinsic viscosity of the product is 0.71 dl/g.

Claims

1. A preparation method of titanium catalyst for polyester synthesis is characterized in that a reaction system for preparing the catalyst mainly comprises polyol, a catalyst carrier, titanate compounds and a small amount of other solvents are added into the polyol system, and a catalyst suspension is obtained through reaction; wherein, the titanate compound is dripped into the reaction system in the way of titanate compound polyalcohol solution, and the reaction temperature is gradually increased at the speed of 10 ℃/h or 20 ℃/h after the dripping is finished.

2. The method according to claim 1, wherein the polyol is a single polyol or a mixed polyol, and the polyol is selected from the group consisting of ethylene glycol, propylene glycol, glycerin, butylene glycol, and isoprene glycol.

3. The production method according to claim 1, wherein the titanate-based compound is added in an amount of 0.1 to 10 times by mass as much as the catalyst carrier.

4. The process according to claim 1, wherein the small amount of the other solvent is added in an amount of 0.1 to 10 vol.% based on the amount of the polyol.

5. The method of claim 1, wherein the catalyst support is selected from the group consisting of silica, alumina, zeolite, diatomaceous earth, and montmorillonite.

6. The method of claim 1, wherein the titanate comprises one or more of ethyl titanate, propyl titanate, and butyl titanate.

7. The process according to claim 1, wherein the small amount of the other solvent is one or more of water and a monohydric lower alcohol.

8. A titanium-based catalyst for polyester synthesis, characterized in that it is a catalyst suspension prepared by the preparation method of any one of claims 1 to 7.