Segmented Reactor with Micro Interfacial Generators for PTA Production
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Solution Overview
Problem
The existing PTA production process using PX results in significant waste of acetic acid solvent under high temperature and high pressure, leading to inefficient energy consumption and low reaction efficiency due to the use of a single reactor for all four oxidation steps with different reaction rate constants.
Innovation Solution
A built-in micro interfacial enhanced reaction system with a segmented reactor design, featuring three reaction zones and micro interfacial generators that break air into micro-bubbles for enhanced mass transfer, along with a circulating heat exchanger for temperature control, allowing for optimized conditions for each reaction step.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a single reactor is used for all four oxidation steps, then the process is simple to operate, but the reaction efficiency is low and energy consumption is high
Solution Approach 1:
The single reactor is divided into multiple reaction zones (first reaction zone, second reaction zone, third reaction zone) with different functions. The first zone handles PX to TALD and TALD to p-TA conversions, the second zone handles p-TA to 4-CBA conversion, and the third zone handles 4-CBA to TA conversion. This segmentation allows each zone to be optimized for its specific reaction, improving overall reaction efficiency while maintaining a single reactor structure for operational simplicity.
2Productivity
If high temperature and high pressure are used for oxidation reactions, then the reaction rate increases, but the consumption of acetic acid solvent increases significantly
Solution Approach 1:
Different reaction zones are provided with locally optimized conditions matching their specific reaction requirements. The first reaction zone operates at relatively lower temperature and pressure suitable for PX oxidation, while subsequent zones are optimized for their respective reactions. This local optimization allows each reaction step to proceed efficiently at minimal energy input, reducing overall acetic acid consumption while maintaining high reaction rates.
3Ease of operation
If the same reaction conditions are applied to all four oxidation steps, then the process is easy to control, but the reaction efficiency is low due to different reaction rate constants
Solution Approach 1:
Each reaction zone is equipped with independent catalyst systems and operating conditions optimized for its specific reaction steps. The first zone uses catalysts optimized for PX and TALD oxidation, the second zone uses catalysts for p-TA oxidation, and the third zone uses catalysts for 4-CBA oxidation. This allows each zone to operate at peak efficiency for its designated reactions while the overall process remains integrated and manageable.
4Productivity
If acetic acid is used as solvent under high temperature and pressure, then the oxidation reactions proceed, but the solvent is wasted in large quantities
Solution Approach 1:
The patent changes the operating parameters (temperature and pressure) for each reaction zone to match the optimal conditions for each oxidation step. By operating at lower temperatures and pressures where possible, and by optimizing each zone's parameters independently, the system achieves effective reaction progression with reduced acetic acid vaporization and decomposition, thereby minimizing solvent waste.
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
This approach reduces energy consumption, conserves acetic acid solvent, and improves reaction efficiency by providing tailored conditions for each reaction step, enabling timely product extraction and enhanced product quality.
Implementation Method 1
a micro interfacial unit disposed inside the reactor... each of the plurality of first micro interfacial generators is respectively disposed at bottoms of the first reaction zone, the second reaction zone and the third reaction zone for breaking air as a reaction raw material into micro-bubbles with a diameter greater than or equal to 1 μm and less than 1 mm
Implementation Method 2
a circulating heat exchanger partially disposed outside the shell... the circulating heat exchanger being connected to the inner cylinder and the micro interfacial unit respectively
Implementation Method 3
generally use acetic acid as a solvent and cobalt acetate, manganese acetate and hydrobromic acid (or tetrabromomethane) as catalysts
Implementation Method 4
The oxidation reaction process of using PX (para-xylene) to produce TA (terephthalic acid)... The four oxidation reactions in the reaction process are series reactions
Data Source
Figure 1
AI summary
A built-in micro interfacial enhanced reaction system and process for PTA production with PX are provided. The system includes a reactor and a micro interfacial unit disposed inside reactor. The reactor includes a shell, an inner cylinder concentrically disposed inside shell, and a circulating heat exchanger partially disposed outside shell, inner cylinder having a bottom end connected to inner bottom surface of the shell in closed manner and an open top end, a region between shell and inner cylinder being first reaction zone, inner cylinder containing second reaction zone and third reaction zone from top to bottom, circulating heat exchanger being connected to inner cylinder and micro interfacial unit respectively. The invention can solve problems of large waste of reaction solvent acetic acid under high temperature and high pressure and being unable to take out the product TA in time during existing process of PTA production with PX.