Homogenized PTA Slurry for DOTP Esterification
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Solution Overview
Problem
The production of dioctyl terephthalate (DOTP) plasticizers is hindered by the insolubility of terephthalic acid (PTA) in 2-ethylhexanol, leading to slow and time-consuming heterogeneous solid-liquid reactions, and existing methods only partially reduce synthesis time without significantly improving reactivity.
Innovation Solution
Homogenizing PTA into fine particles with a specific surface area increase, followed by esterification with a titanium-based catalyst under controlled pressure and temperature, and neutralization with an alkaline metal hydroxide solution to enhance reactivity and reduce reaction time by at least 37.5%, while maintaining high purity and low odor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If PTA is used as large particles in conventional esterification, then the reaction proceeds slowly due to limited surface area, but reducing particle size further may cause agglomeration and sedimentation
Solution Approach 1:
The PTA particles are segmented into finer particles (80-110 μm) using a homogenizer, increasing the specific surface area by 5-11%. This segmentation provides more reaction sites for esterification while the controlled particle size range prevents excessive agglomeration, resolving the contradiction between reaction rate and particle stability
Solution Approach 2:
The particle size parameter is optimized to a specific range (80-110 μm) through homogenization. This parameter change increases surface area for faster reaction while maintaining particles large enough to avoid severe agglomeration and sedimentation, balancing productivity and stability
2Productivity
If conventional esterification is used without homogenization, then the process is simpler, but the reaction time is prolonged by at least 5 hours
Solution Approach 1:
PTA is pre-homogenized into fine particles (80-110 μm) with increased specific surface area before the esterification reaction. This preliminary action of particle size reduction enables significantly faster reaction (reducing time by 37.5-50%) while the homogenization step is a relatively simple mechanical process that does not substantially increase overall process complexity
3Productivity
If PTA is not homogenized, then the manufacturing process is less complex, but the reaction liquid bubbles and attaches to tank walls, reducing reaction efficiency
Solution Approach 1:
PTA is pre-homogenized into fine particles (80-110 μm) with increased specific surface area before the esterification reaction. This preliminary action of particle size reduction enables significantly faster reaction (reducing time by 37.5-50%) while the homogenization step is a relatively simple mechanical process that does not substantially increase overall process complexity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method significantly shortens the DOTP synthesis time, increases reaction efficiency, and produces a high-purity, low-odor plasticizer with improved physical properties, enhancing productivity and energy efficiency.
Implementation Method 1
PTA is in advance homogenized into a fine particle with homogenizer. As a result, PTA is unlikely to agglutinate, and the reaction liquid is unlikely to bubble and attach to walls of the reaction tank. Particularly, the beforehand homogenization-processed PTA has its surface become wrinkles, which provide increased surface area and facilitate permeation of 2-EH for reaction inside PTA
Implementation Method 2
Currently, industrial production of DOTP mainly uses titanate as the catalyst
Implementation Method 3
DOTP plasticizers are synthesized by esterifying purified terephthalic acid (hereinafter referred to as PTA) and 2-ethylhexanol (hereinafter referred to as 2-EH)
Implementation Method 4
neutralizing the reaction mixture with an aqueous solution of alkaline metal hydroxide that contains a hydroxide mixture of 5-20 wt %, until the reaction mixture having its acid value reduced to below 0.07 mgKOH/g
Data Source
AI summary
A method for enhancing reaction efficiency of a terephthalate plasticizer involves using a homogenizer to fine PTA to slurry having a particle size of 80-110 μm, and esterifying the PTA slurry with a C6-C10 alcohol in the presence of a titanium-based catalyst. The reactivity is enhanced by more than 37.5%, and the terephthalate plasticizer so synthetized is low-odor and has a purity of more than 99.5% as well as good physical properties such as acid value, color, and index of refraction.