Allyl Acetate Purification via Catalyst Decomposition
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Solution Overview
Problem
Current methods for purifying allyl acetate produced by propylene acetoxylation are energy-intensive and costly due to the need for multiple distillation columns, and high-boiling impurities like allyl diacetate and 3-acetoxypropionaldehyde complicate the process, potentially poisoning ion-exchange resins used in the subsequent hydrolysis step.
Innovation Solution
The process involves distilling an acetoxylation mixture at elevated pressure to remove propylene and generate a first bottoms mixture, followed by flash vaporization and contact with a solid acidic catalyst to decompose allyl diacetate and 3-acetoxypropionaldehyde, allowing for the separation of allyl acetate and acrolein, which can then be distilled to produce a purified allyl acetate stream suitable for hydrolysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple distillation columns are used to purify allyl acetate, then purification effectiveness is improved, but energy consumption and capital expense increase
Solution Approach 1:
The patent changes the physical state parameter of the mixture from liquid to vapor phase, enabling decomposition reactions that convert high-boiling impurities into more volatile compounds. This parameter change allows purification through a single distillation column rather than multiple columns, reducing energy consumption while maintaining purification effectiveness
Solution Approach 2:
The patent converts harmful high-boiling impurities (allyl diacetate and 3-acetoxypropionaldehyde) into beneficial more-volatile decomposition products (acrolein and acetic acid) through vapor-phase decomposition. This transformation allows the impurities to be removed more easily along with other volatile components in a single distillation step, turning a purification obstacle into a simplification opportunity
2Manufacturing precision
If multiple distillation columns are used to purify allyl acetate, then purification effectiveness is improved, but process complexity increases
Solution Approach 1:
The patent merges the decomposition function and distillation purification function into a single integrated process step. By performing vapor-phase decomposition followed by single-column distillation, the patent combines what would traditionally require multiple separate units into one streamlined process, reducing device complexity while maintaining purification effectiveness
Solution Approach 2:
The patent uses parameter changes (vaporization) to enable a single distillation column to achieve the separation effectiveness that would otherwise require multiple columns. The phase change allows impurities to be converted into volatile forms that can be separated in one step, simplifying the overall process configuration
3Ease of manufacture
If high-boiling impurities are present in allyl acetate, then product recovery is simplified, but resin poisoning occurs in hydrolysis step
Solution Approach 1:
The patent converts harmful high-boiling impurities into beneficial volatile decomposition products through vapor-phase decomposition. The impurities (allyl diacetate and 3-acetoxypropionaldehyde) are transformed into acrolein and acetic acid, which are more volatile and can be removed in the distillation step, preventing them from poisoning the ion-exchange resin in the subsequent hydrolysis process
Solution Approach 2:
The patent performs preliminary decomposition of high-boiling impurities before the distillation and hydrolysis steps. By converting the impurities to volatile compounds in advance, the patent prevents potential resin poisoning from occurring in the hydrolysis step, ensuring process reliability
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 method reduces energy consumption, eliminates high-boiling impurities, prevents resin poisoning, and simplifies the purification process, enabling the recovery of allyl acetate as a bottoms product while avoiding the capital and yield losses associated with multi-tower distillation schemes.
Implementation Method 1
contacting the flashed vapor with a solid acidic catalyst under conditions effective to decompose the allyl diacetate and the 3-acetoxypropionaldehyde
Implementation Method 2
The first bottoms mixture is flash vaporized
Implementation Method 3
An acetoxylation mixture is distilled at elevated pressure to remove propylene
Data Source
AI summary
A process for purifying allyl acetate is disclosed. An acetoxylation mixture is distilled at elevated pressure to remove propylene and generate a first bottoms mixture comprising allyl acetate, acetic acid, acrolein, allyl diacetate, and 3-acetoxypropionaldehyde. The first bottoms mixture is flash vaporized, and the resulting vapor is contacted with a solid acidic catalyst under conditions effective to decompose allyl diacetate and 3-acetoxypropionaldehyde. The flashed product, which comprises allyl acetate, acetic acid, and acrolein, is then distilled to remove acrolein and generate a second bottoms mixture comprising allyl acetate and acetic acid. The second bottoms mixture can be used to manufacture allyl alcohol.