Lactide Purification via Cooling Crystallization
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Solution Overview
Problem
Conventional lactide purification methods face issues with thermal polymerization or hydrolysis during distillation, leading to decreased yield and high energy expenditure, along with complex and costly apparatus.
Innovation Solution
A method involving rapid cooling of lactide vapor using a solvent to prevent side reactions, followed by crystallization and filtration to produce high-purity lactide crystals, utilizing a catalytic reaction unit with a solid catalyst and a condensing unit with a solvent like ethanol to collect and separate lactide crystals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If distillation is used to purify lactide, then separation is achieved, but thermal polymerization or hydrolysis occurs leading to decreased yield
Solution Approach 1:
The patent changes the purification parameter from thermal distillation to cooling crystallization. By controlling temperature parameters during cooling, lactide vapor is condensed and crystallized directly, avoiding the high temperature distillation process that causes thermal polymerization and hydrolysis, thus maintaining both high purity and high yield
Solution Approach 2:
The patent replaces the thermal-mechanical distillation system with a cooling-crystallization system. Instead of using heat to separate lactide, the process uses controlled cooling to condense and crystallize lactide vapor directly, substituting a different physical mechanism that avoids thermal degradation
2Manufacturing precision
If distillation is used to purify lactide, then separation is achieved, but energy expenditure increases
Solution Approach 1:
The patent changes the energy utilization parameter from high-temperature distillation to low-temperature cooling crystallization. By operating at lower temperatures during the crystallization process, the energy consumption is significantly reduced while still achieving effective separation and purification of lactide
3Productivity
If two-step reaction is used to prepare lactide, then production process is established, but apparatus complexity increases
Solution Approach 1:
The patent merges the polymerization and purification steps into a single integrated process. The polymerization reaction and crystallization purification occur in one continuous operation, eliminating the need for separate apparatus for each step, thus simplifying the overall system while maintaining productivity
Solution Approach 2:
The patent creates a multi-functional system where the reaction vessel serves both as the polymerization reactor and the crystallization chamber. This universal apparatus performs multiple functions (polymerization, condensation, crystallization, and filtration) without requiring additional specialized equipment, reducing apparatus complexity
4Productivity
If two-step reaction is used to prepare lactide, then production process is established, but production cost increases
Solution Approach 1:
The patent combines multiple process steps into one operation, reducing the number of equipment components and operational steps required. This integration eliminates redundant equipment costs and reduces energy consumption, thereby lowering overall production costs while maintaining lactide productivity
Solution Approach 2:
The patent implements a system where the filtration medium and reaction byproducts are easily separated and recovered. The filtration step allows for simple recovery of unreacted materials and catalysts, reducing waste disposal costs and raw material losses, thus improving ease of manufacture
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 minimizes lactide loss, increases yield, reduces production costs, and simplifies the process by directly converting lactide vapor into crystals, achieving optical purities of 98% or higher without the need for prepolymerization.
Implementation Method 1
lactide vapor is cooled rapidly using a solvent
Implementation Method 2
lactide vapor is cooled rapidly using a solvent to prevent side reactions and lactide is crystallized and separated
Implementation Method 3
lactide is crystallized and separated
Data Source
AI summary
The present invention relates to a method and apparatus for preparation of lactide using a lactide purification process, comprising introducing an aqueous solution comprising lactic acid into a reactor filled with a catalyst and reacting the same to produce crude lactide vapor; and purifying the crude lactide vapor to produce lactide crystals, wherein a first purification comprises collecting and crystallizing the crude lactide vapor using a first solvent to produce lactide crystals, and separating the lactide crystal from a residue through filtration.