Propylene Oxide Purification via Liquid-Liquid Extraction
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Solution Overview
Problem
Current methods for purifying propylene oxide are energy-intensive and inefficient in removing impurities such as acetone, water, methanol, methyl formate, aldehydes, and hydrocarbons, requiring significant energy input to achieve low levels of impurities.
Innovation Solution
A method involving liquid/liquid solvent extraction using a glycol and a C7 or greater alkane to separate propylene oxide from impurities, followed by distillation steps to produce a high-purity propylene oxide product with less than 0.1 weight percent impurities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional distillation processes are used to purify propylene oxide, then high purity product can be achieved, but energy consumption is extremely high
Solution Approach 1:
The patent introduces an intermediary substance (solvent) that facilitates the separation of propylene oxide from impurities through liquid-liquid extraction. The solvent selectively interacts with impurities, allowing propylene oxide to be transferred to the product phase with reduced impurity content, thereby achieving purification without the high energy input required by traditional distillation
Solution Approach 2:
The patent changes the physical-chemical parameters of the system by introducing a solvent with specific solubility characteristics. By adjusting the solvent's affinity for different components (propylene oxide vs. impurities), the process achieves efficient separation at lower energy costs compared to thermal distillation methods
2Manufacturing precision
If multiple distillation stages are used to remove impurities, then impurity levels can be reduced to very low levels, but the process becomes extremely energy-intensive
Solution Approach 1:
Instead of using multiple thermal distillation stages, the patent employs a solvent as an intermediary that selectively absorbs or extracts impurities from the propylene oxide stream. This chemical-physical interaction enables high-level impurity removal through a single extraction stage rather than requiring multiple energy-intensive distillation columns
Solution Approach 2:
The patent replaces the mechanical/thermal system of multi-stage distillation with a chemical-physical extraction system. The solvent-based extraction process substitutes for the need of multiple heating and condensation cycles, achieving equivalent or superior purification with significantly lower energy input
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 effectively reduces impurity levels in propylene oxide, achieving high purity with lower energy consumption compared to traditional distillation processes, thereby reducing production costs.
Implementation Method 1
contacting the impure propylene oxide with a glycol and a C7 or greater alkane in a liquid/liquid solvent extraction
Implementation Method 2
distilling the alkane fraction in one or more steps to produce an alkane bottoms stream and a propylene oxide product
Data Source
Figure 1
AI summary
The invention is a method of purifying propylene oxide containing acetone, water, methanol, methyl formate, aldehydes, and hydrocarbons impurities. The method comprises contacting the propylene oxide with a glycol and a C7 or greater alkane in a liquid/liquid solvent extraction, and separating propylene oxide having reduced impurities content. The purified propylene oxide may be produced by reacting propylene and a hydroperoxide to produce a crude propylene oxide effluent, distilling the crude effluent to produce a propylene oxide stream which contains 1-5 weight percent of the impurities, contacting the propylene oxide stream with a glycol and a C7 or greater alkane in a liquid/liquid solvent extraction, then separating an alkane fraction comprising propylene oxide from a glycol fraction, and distilling the alkane fraction in one or more steps to produce an alkane bottoms stream and a propylene oxide product having less than 0.1 weight percent impurities.