Acrylic Acid Separation Using Two-Stage Cooling and Extraction
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Solution Overview
Problem
Conventional methods for preparing acrylic acid from propylene result in environmental pollution and high energy consumption due to the use of fossil resources, and the dehydration of lactic acid at high concentrations leads to oligomer formation and increased water content, necessitating excessive energy for separation.
Innovation Solution
A method involving a two-stage cooling process using two cooling towers and a distillation-extraction process to separate acrylic acid from a lactic acid dehydration reaction, minimizing energy use and acrylic acid loss by controlling the composition of streams in each stage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If lactic acid is used at a high concentration for dehydration reaction, then the reaction efficiency is improved, but oligomers are produced which lower the concentration of lactic acid participating in the reaction
Solution Approach 1:
The patent divides the dehydration reaction process into multiple stages with different lactic acid concentration ranges. The reaction is conducted in a first stage at 20-40°C with 5-20 wt% lactic acid, followed by a second stage at 40-80°C with 10-30 wt% lactic acid. This segmentation allows optimization of reaction conditions at each stage to prevent oligomer formation while maintaining high reaction efficiency.
2Stability of the object's composition
If the concentration of lactic acid is lowered to prevent oligomer formation, then oligomer production is reduced, but the amount of water increases which requires more energy for water removal
Solution Approach 1:
The patent optimizes the lactic acid concentration parameter within a specific range of 5-30 wt% across two reaction stages, and controls the pH parameter between 2-4 during the reaction. These parameter changes enable the system to achieve both low oligomer formation and reduced energy consumption for water removal, as the optimized concentration range balances reaction efficiency with water content management.
3Productivity
If conventional oxidation method using propylene is used, then acrylic acid can be produced, but acetic acid by-product is produced which is difficult to separate from acrylic acid
Solution Approach 1:
The patent replaces the conventional propylene oxidation route with a lactic acid dehydration route. This extraction of the problematic oxidation step eliminates the formation of acetic acid by-product that is difficult to separate. The dehydration reaction of lactic acid directly produces acrylic acid with water as the only by-product, which is easily separable, thus solving the separation difficulty issue.
4Productivity
If propylene from crude oil is used as raw material, then acrylic acid can be produced, 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 in the feedstock source enables production of acrylic acid from renewable resources, reducing dependence on crude oil, lowering raw material costs, and minimizing environmental pollution while maintaining production efficiency.
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
Reduces energy consumption and acrylic acid loss by effectively separating water and acrylic acid using two cooling towers and a distillation column, enhancing recovery rates and reducing waste.
Implementation Method 1
supplying a reactor discharge stream including the reaction product to a first cooling tower and supplying an upper discharge stream from the first cooling tower to a second cooling tower
Implementation Method 2
supplying an upper discharge stream from the extraction column and a second acrylic acid aqueous solution stream discharged from a lower portion of the first cooling tower to a distillation column; and separating the acrylic acid from a lower discharge stream from the distillation column
Implementation Method 3
supplying a first acrylic acid aqueous solution stream discharged from a lower portion of the second cooling tower to an extraction column
Data Source
AI summary
Provided is a method for preparing an acrylic acid including: supplying a lactic acid aqueous solution to a reactor and performing a dehydration reaction to prepare a reaction product including an acrylic acid; supplying a reactor discharge stream including the reaction product to a first cooling tower and supplying an upper discharge stream from the first cooling tower to a second cooling tower; supplying a first acrylic acid aqueous solution stream discharged from a lower portion of the second cooling tower to an extraction column; supplying an upper discharge stream from the extraction column and a second acrylic acid aqueous solution stream discharged from a lower portion of the first cooling tower to a distillation column; and separating the acrylic acid from a lower discharge stream from the distillation column.