Lactic Acid Dehydration Purification via Two-Stage Cooling
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Solution Overview
Problem
The existing methods for preparing acrylic acid, such as air oxidizing propylene, face challenges in separating by-products like acetic acid and rely on fossil resources, leading to high raw material costs and environmental pollution, while dehydration reactions of lactic acid struggle with recovering unreacted lactic acid due to oligomerization at high temperatures, increasing energy consumption and process costs.
Innovation Solution
A method involving a dehydration reaction of lactic acid, where the reaction product is first cooled in a first cooling tower to separate unreacted lactic acid from water and a light gas component, then further purified in a second cooling tower to obtain high-purity acrylic acid, reducing energy costs and avoiding additional distillation steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If unreacted lactic acid is recovered after distillation, then acrylic acid purification is achieved, but energy consumption increases and lactic acid oligomerization occurs
Solution Approach 1:
The patent applies preliminary action by separating unreacted lactic acid from the reaction product BEFORE distillation through extraction with organic solvent. This prevents lactic acid from entering the distillation column where it would oligomerize at high temperatures, thereby reducing energy consumption and avoiding by-product formation while still achieving acrylic acid purification.
Solution Approach 2:
The patent segments the purification process into two distinct stages: (1) extraction stage where unreacted lactic acid is removed from the reaction product using organic solvent, and (2) distillation stage where acrylic acid is purified. This segmentation allows each stage to operate under optimal conditions, preventing lactic acid oligomerization during distillation.
2Productivity
If lactic acid is recovered at high concentration and high temperature, then recovery efficiency improves, but oligomerization reaction increases making recovery difficult
Solution Approach 1:
The patent changes the parameters under which lactic acid separation occurs by using extraction with organic solvent at lower temperatures instead of relying on high-temperature distillation. This parameter change prevents oligomerization while maintaining effective separation, thereby preserving both recovery efficiency and recoverability.
Solution Approach 2:
The patent introduces an intermediary substance (organic solvent) to facilitate the separation of unreacted lactic acid from the reaction product. This intermediary enables selective extraction of lactic acid at lower temperatures, avoiding the oligomerization that would occur under high-temperature conditions.
3Productivity
If propylene is used as raw material for acrylic acid production, then production capacity is maintained, but raw material costs increase and environmental pollution occurs
Solution Approach 1:
The patent fundamentally changes the raw material parameter from propylene (fossil-based) to lactic acid (biomass-based). This parameter change maintains acrylic acid production capacity while eliminating the environmental pollution and raw material cost issues associated with fossil resource dependency.
Solution Approach 2:
The patent converts the previously harmful dependency on fossil resources into a beneficial use of renewable biomass resources. By using lactic acid derived from biomass as the raw material, the process transforms an environmentally harmful production method into a sustainable, carbon-neutral process.
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 effectively reduces energy consumption and process costs by separating unreacted lactic acid before distillation, improving the recovery rate and obtaining high-purity acrylic acid while using carbon-neutral biomass as a raw material, thus addressing environmental concerns and economic inefficiencies.
Implementation Method 1
supplying the reaction product to a first cooling tower to separate the reaction product into a lower fraction containing unreacted lactic acid and an upper fraction containing water, a light gas component, and acrylic acid
Implementation Method 2
supplying the upper fraction of the first cooling tower to a second cooling tower to separate a lower fraction containing water and acrylic acid therefrom
Implementation Method 3
obtaining a reaction product including unreacted lactic acid, water, a light gas component, and acrylic acid by supplying a lactic acid aqueous solution to a reactor to allow a dehydration reaction to proceed
Data Source
AI summary
A method for preparing acrylic acid, the method including: obtaining a reaction product including unreacted lactic acid, water, a light gas component, and acrylic acid by supplying a lactic acid aqueous solution to a reactor to allow a dehydration reaction to proceed; supplying the reaction product to a first cooling tower to separate the reaction product into a lower fraction containing unreacted lactic acid and an upper fraction containing water, a light gas component, and acrylic acid; supplying the upper fraction of the first cooling tower to a second cooling tower to separate a lower fraction containing water and acrylic acid therefrom; and obtaining acrylic acid by purifying the lower fraction of the second cooling tower.