Ester Removal from Vapor via Aqueous Hydrolysis
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Solution Overview
Problem
Existing methods for removing esters like lactide from vapor mixtures face issues with precipitation and viscosity increases due to solubility limitations and the need for additional liquids or caustic solutions, leading to complex flow management and potential blockages in condensation and washing systems.
Innovation Solution
A method involving a countercurrent column process where the vapor mixture is contacted with an aqueous solution, followed by a heating, reaction, and cooling step, allowing for efficient dissolution and hydrolysis of esters without the need for additional liquids or caustic solutions, thereby maintaining low liquid temperatures and pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the vapor mixture is condensed and washed by bringing it into contact with a stream of condensation and washing liquid containing an aqueous solution of lactic acid, then the lactide dissolves in the liquid, but the solubility limit of lactide is exceeded and solids precipitate in the circulation liquid causing blockages
Solution Approach 1:
The invention changes the chemical composition parameter of the washing liquid by adding caustic solution (碱液), which transforms the system from a simple aqueous lactic acid solution to a碱性 environment that prevents lactide precipitation while maintaining dissolution capacity
Solution Approach 2:
The caustic solution acts as an intermediary substance that mediates between the lactide and the aqueous lactic acid solution, facilitating lactide dissolution while preventing precipitation by maintaining alkaline conditions in the circulation liquid
2Reliability
If additional liquids or caustic solutions are added to prevent precipitation, then the solubility limit is maintained, but the device complexity and flow management become more complex
Solution Approach 1:
The invention implements a self-regulating system where the caustic solution continuously maintains alkaline conditions in the circulation liquid, automatically preventing lactide precipitation without requiring complex external control mechanisms or multiple liquid addition systems
3Quantity of substance
If the circulation liquid is used to wash and condense vapor mixtures, then the lactide is removed from vapors, but the viscosity of the liquid increases and the distribution over the bed or packing is hindered
Solution Approach 1:
The invention changes the pH parameter of the circulation liquid by maintaining alkaline conditions through caustic solution addition, which prevents lactide polymerization and viscosity increase, thereby maintaining good liquid distribution characteristics throughout the packing
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 ester content in the aqueous solution, preventing precipitation and blockages, and allows for robust and controlled removal of esters like lactide, improving the efficiency and stability of the process without increasing temperatures or adding extra components.
Implementation Method 1
bringing the vapor mixture into contact with an aqueous solution, wherein a portion of the ester is dissolved in or otherwise transferred to the aqueous solution
Implementation Method 2
a heating step, a reaction step having a residence time and a temperature
Implementation Method 3
the residence time and the temperature in the reaction step are sufficient to substantially reduce the content of the ester in the aqueous solution through a dissolution and hydrolysis of the ester
Implementation Method 4
a cooling step, wherein the heating step precedes the reaction step, the reaction step precedes the cooling step
Data Source
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AI summary
A method for the removal of an ester (3') from a vapor mixture (5') containing the ester (3') is disclosed. The method comprises the steps of by bringing the vapor (5) mixture (5') into contact with an aqueous solution (6') containing the acid (4') corresponding to the ester (3'), wherein a portion of the ester (3') is dissolved in or otherwise transferred to the aqueous solution (6'), and the aqueous solution (6') is after the contact led in a circulation (73), the aqueous solution (6') is processed in the circulation (73) in a process comprising: a heating step (240), a (10) reaction step (250) having a residence time and a temperature, a cooling step (260), wherein the heating step (240) precedes the reaction step (250), the reaction step (250) precedes the cooling step (260), and the residence time and the temperature in the reaction step (250) are sufficient to substantially reduce the content of the ester (3') in the aqueous solution (6'). The invention further (15) relates to an apparatus (1) for carrying out said process. The present invention further relates also to the use of the apparatus (1) in the method of the invention, preferably in the production of a lactide (13') or a polylactic acid polymer (12').