Levulinic Acid Purification via Melt Crystallization
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Solution Overview
Problem
Current methods for purifying levulinic acid, such as distillation and crystallization, often result in impurities like angelica lactone, formic acid, and low shelf stability, and are inefficient due to unpredictable melt crystallization processes and the need for solvents or low temperature cooling, which complicates the purification of levulinic acid to the desired 95-99% purity required for pharmaceutical and cosmetic applications.
Innovation Solution
A melt crystallization process involving a composition with at least 75% levulinic acid, cooled to a specific temperature range, and contacted with levulinic acid crystal seeds to crystallize, followed by optional sweating and repeated cycles to achieve a purity of at least 98% without occluding impurities, reducing energy consumption and ensuring clear, stable product.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If distillation is used to purify levulinic acid, then concentration is improved, but impurities like angelica lactone are formed causing coloration and low shelf stability
Solution Approach 1:
The patent applies melt crystallization, a phase transition process, to purify levulinic acid. The crude levulinic acid composition is cooled to crystallize pure levulinic acid while leaving impurities in the liquid phase. This resolves the contradiction by achieving high concentration through crystallization rather than distillation, thereby avoiding angelica lactone formation while obtaining pure product.
2Manufacturing precision
If crystallization is used to purify levulinic acid, then purity is improved, but the process becomes unpredictable and complex
Solution Approach 1:
The patent applies preliminary action by pre-cooling the crude levulinic acid composition to a temperature below its melting point before adding crystal seeds. This preliminary cooling step ensures that the subsequent crystallization process proceeds predictably and efficiently, reducing process complexity while achieving high purity.
Solution Approach 2:
The patent uses crystal seeds as an intermediary to initiate and control the crystallization process. By adding pre-formed levulinic acid crystals to the cooled crude composition, the process becomes predictable and controllable, eliminating the unpredictability associated with spontaneous crystallization while maintaining high purity.
3Manufacturing precision
If crystallization from diluted levulinic acid is used, then purity is improved, but low temperatures and solvents are required increasing complexity
Solution Approach 1:
The patent applies parameter changes by working with concentrated levulinic acid composition (at least 75 wt% purity) rather than diluted solutions. The process uses cooling to a specific temperature range (0°C to 20°C below melting point) without requiring solvents, thereby achieving high purity while simplifying the process by eliminating solvent recovery steps and extreme temperature requirements.
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
The process effectively reduces impurities, achieves high purity levulinic acid with trace amounts of formic acid and no angelica lactone, ensuring long shelf life and clear composition, while simplifying the operation by avoiding strong undercooling and solvent use, thus meeting the purity requirements for pharmaceutical and cosmetic applications.
Implementation Method 1
Cooling composition 1 to at least one temperature Tc, wherein Tc is a temperature in the range 1.23*(W1) -104.5 ≤ Tc (°C) ≤ 1.23*(W1) - 89.5, wherein W1 is the weight% of levulinic acid in composition 1
Implementation Method 2
Cooling composition 1 to at least one temperature Tc to obtain a cooled composition 1
Implementation Method 3
Bringing the cooled composition 1 into contact with levulinic acid crystal seeds
Implementation Method 4
Draining of liquid 1
Implementation Method 5
Heating the crystals 1 at a temperature between 5 and 40 °C to obtain crystals 2 and liquid 2
Data Source
Figure 1~2
AI summary
The invention is directed to a process for the purification of levulinic acid comprising the following steps: a. Providing a composition 1, comprising at least 75 wt% of levulinic acid; b. Cooling composition 1 to at least one temperature Tc, wherein Tc is a temperature in the range 1.23*(W1) -104.5‰¤ Tc (ºC) ‰¤ 1.23*(W1) - 89.5, wherein W1 is the weight% of levulinic acid in composition 1, to obtain a cooled composition 1; c. Performing melt crystallization of composition 1 comprising the steps of: i. Bringing the cooled composition 1 into contact with levulinic acid crystal seeds, ii. Allowing the levulinic acid in composition 1 to crystallize at at least one temperature Tc to obtain crystals 1 and liquid 1, and iii. Draining of liquid 1; d. Optionally, treating crystals 1, after draining of liquid 1, by sweating, according to the following steps: i. Heating the crystals 1 at a temperature between 5 and 40 ºC to obtain crystals 2 and liquid 2, and ii. Draining of liquid 2; e. Melting the crystals 1 or 2, after draining of liquid 1 or 2, to obtain composition 2, f. Determining the levulinic acid concentration in composition 2 and, in case the levulinic acid concentration is below a predetermined value, repeating steps b, c, optionally d, and e, as many times as necessary to obtain a final composition with a predetermined levulinic acid concentration.