Levulinic Acid Purification via Melt Crystallization
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Solution Overview
Problem
Existing processes for producing levulinic acid from C6 carbohydrate-containing feedstocks result in high concentrations of angelica lactone, which are detrimental and reduce color stability, and often lack formic acid, which is beneficial in certain applications.
Innovation Solution
A novel process involving acid catalyzed hydrolysis of C6 carbohydrate-containing feedstocks, followed by unique purification steps including evaporation and melt crystallization, to produce a levulinic acid composition with at least 98 wt% levulinic acid, 5-5000 wppm formic acid, and less than 1000 wppm angelica lactone, optimizing the ratio of by-products for improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional purification processes are used for levulinic acid production, then production efficiency is maintained, but angelica lactone concentration becomes too high causing color instability
Solution Approach 1:
The patent changes the purification parameters by controlling pH levels and using specific temperature ranges during evaporation and crystallization steps. By maintaining pH between 2-4 during evaporation and using controlled cooling rates during melt crystallization, the process selectively removes angelica lactone while preserving levulinic acid, thus improving color stability without sacrificing production efficiency
Solution Approach 2:
The patent employs phase transition techniques including evaporation (liquid to vapor) to concentrate the levulinic acid solution, followed by melt crystallization (liquid to solid) to purify the product. These phase transitions enable selective separation of angelica lactone from levulinic acid based on their different physical properties, resolving the contradiction between maintaining production efficiency and reducing harmful by-products
2Adaptability or versatility
If conventional purification processes are used for levulinic acid production, then processing simplicity is maintained, but formic acid is completely removed reducing performance in certain applications
Solution Approach 1:
The patent carefully controls pH parameters during purification to retain formic acid at optimal concentrations (0.1-5.0 wt%). By adjusting pH to specific ranges and controlling the extent of neutralization, the process preserves beneficial formic acid while removing harmful angelica lactone, thereby improving adaptability for hydrogenation applications without over-purifying the product
3Reliability
If multiple purification steps are added to reduce angelica lactone, then color stability improves, but process complexity increases
Solution Approach 1:
The patent combines evaporation and melt crystallization into an integrated purification sequence that achieves high color stability. By merging these steps with pH control and using a continuous flow approach where the output of one step feeds directly into the next, the process achieves effective angelica lactone removal without requiring multiple separate, complex purification units
Solution Approach 2:
The melt crystallization step utilizes the inherent physical properties of levulinic acid and angelica lactone (different melting points and solubilities) to achieve self-separation. The process requires minimal external intervention beyond temperature control, as the compounds naturally separate based on their thermodynamic properties, reducing the need for additional complex purification equipment
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 achieves improved color stability and tunable ratios of by-products, specifically enhancing the MeTHF/1,4-pentanediol ratio through controlled formic acid concentration, while minimizing angelica lactone to prevent colored compound formation.
Implementation Method 1
acid catalyzed hydrolysis of C6 carbohydrate-containing feedstocks
Implementation Method 2
unique purification steps including evaporation
Implementation Method 3
unique purification steps including evaporation and melt crystallization
Data Source
AI summary
The invention is directed to a levulinic acid composition A comprising: a. at least 95wt% of levulinic acid; b. between 5 wppm and 5000 wppm of formic acid; and c. less than 1000 wppm of angelica lactone, based on the total weight of the composition. The invention is also directed to process for the isolation of a levulinic acid composition, comprising the following steps: a. Performing acid catalyzed hydrolysis of a C6 carbohydrate-containing feedstock to obtain reaction product X, b. Subjecting of reaction product X to solid-liquid separation to provide a composition1, c. Feeding composition 1 to at least two purification steps to treat composition 1 to obtain a levulinic acid composition, wherein a second or a further purification step is a melt crystallization step.