Bio-based Propylene Glycol Refining via Azeotropic Solvent Separation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for refining bio-based propylene glycol face challenges in separating propylene glycol from impurities like butanediol, pentanediol, and hexanediol due to their similar boiling points, resulting in low distillation yields and high energy consumption.
Innovation Solution
A process involving the use of azeotropic solvents, such as C5-C20 oleophilic alcohol compounds, C5-C20 alkanes, and C4-C20 oleophilic ketone compounds, is employed to form an azeotrope with propylene glycol, allowing for the separation of propylene glycol from impurities through rectification after adding water to dissolve propylene glycol.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional rectification method is used to separate propylene glycol from impurities, then separation is attempted, but distillation yield is low and energy consumption is high due to close boiling points
Solution Approach 1:
An azeotropic solvent is introduced as an intermediary substance to form an azeotrope with propylene glycol. This azeotrope has a significantly lower boiling point than pure propylene glycol, creating a large temperature difference that enables efficient separation from impurities like butanediol, pentanediol, and hexanediol through rectification, thereby improving both purity and distillation yield
Solution Approach 2:
The boiling point parameter of propylene glycol is changed by forming an azeotrope with the solvent. The azeotropic mixture exhibits a lower boiling point than the pure component, transforming the separation problem from one requiring high-energy direct distillation to one amenable to efficient rectification with large temperature differences
2Manufacturing precision
If traditional rectification method is used to separate propylene glycol from impurities, then separation is attempted, but energy consumption is high due to close boiling points
Solution Approach 1:
The azeotropic solvent acts as a mediator that enables separation at lower temperatures. By forming an azeotrope with a significantly lower boiling point, the process avoids the high energy consumption associated with distilling pure propylene glycol at its high boiling point, reducing overall energy requirements while maintaining separation efficiency
Solution Approach 2:
The temperature parameter is changed through azeotrope formation. The separation process operates at the lower azeotropic boiling point rather than the high boiling point of pure propylene glycol, significantly reducing the thermal energy input required for the separation process
3Manufacturing precision
If azeotropic solvent is used to separate propylene glycol from butanediol, then separation is achieved, but other impurities with close boiling points remain unresolved
Solution Approach 1:
The azeotropic solvent system is designed to simultaneously handle multiple types of impurities (butanediol, pentanediol, hexanediol, propylene carbonate) through a single rectification process. The solvent's properties enable it to form an azeotrope with propylene glycol that has a universally low boiling point, making the separation effective against various impurity types with different boiling points
Solution Approach 2:
The separation approach moves from relying solely on small boiling point differences to utilizing a large temperature dimension created by azeotrope formation. This dimensional change in temperature difference enables the simultaneous separation of multiple impurity types that would otherwise require multiple sequential separation steps
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 process achieves a purity of 99.50% or more propylene glycol with a recovery rate of 80% or more, effectively addressing the limitations of traditional rectification methods.
Implementation Method 1
one, two or more of C5-C20 oleophilic alcohol compounds, C5-C20 alkanes and C4-C20 oleophilic ketone compounds are subjected to azeotropism as an azeotropic solvent together with the bio-based propylene glycol to obtain an azeotrope containing propylene glycol
Implementation Method 2
water is added to dissolve the propylene glycol in the azeotrope
Implementation Method 3
the water-insoluble azeotropic solvent is separated from the propylene glycol aqueous solution
Data Source
AI summary
The invention provides a process for refining bio-based propylene glycol, wherein impurities having boiling points close to that of propylene glycol are separated. In this process, C5-C20 oleophilic alcohol compounds, C5-C20 alkanes and/or C4-C20 oleophilic ketone compounds are subjected to azeotropism as an azeotropic solvent together with the bio-based propylene glycol to obtain an azeotrope containing propylene glycol. Then the azeotropic solvent in the azeotrope is separated to obtain a crude propylene glycol which is further purified to obtain propylene glycol.