Dioxolane Purification via Nitroethane Extraction
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Solution Overview
Problem
Existing processes for preparing dioxolane result in high losses of the valuable product and require significant amounts of auxiliary substances that need to be purified or discharged, leading to inefficiencies and waste.
Innovation Solution
A process involving a reaction distillation device where ethylene glycol and formaldehyde are reacted in the presence of a catalyst, with a phase separation unit and organic extracting agent, allowing for the separation and recycling of components, thereby increasing dioxolane yield and purity while minimizing losses and auxiliary substance usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If benzene is used to break the azeotrope in the distillation column, then dioxolane purity is improved, but benzene must be removed in further process steps and is discharged, increasing waste and process complexity
Solution Approach 1:
The patent extracts the harmful azeotropic mixture separation problem by introducing a third component (nitroethane or nitromethane) that forms a heterogeneous azeotrope with water, allowing water to be removed in a separate phase without requiring benzene discharge steps
Solution Approach 2:
The patent uses nitroethane or nitromethane as intermediary substances to break the dioxolane-water azeotrope indirectly, avoiding the need to use benzene and subsequently remove it from the product stream
2Manufacturing precision
If azeotropic distillation with benzene is used, then dioxolane can be separated from water, but additional purification steps are required and process complexity increases
Solution Approach 1:
The patent extracts the complex multi-column separation system by using a single distillation column with a third component that enables selective water removal through heterogeneous azeotrope formation, eliminating the need for separate benzene removal columns
Solution Approach 2:
The patent changes the compositional parameter of the distillation system by introducing nitroethane or nitromethane, which alters the azeotropic behavior and enables water to be removed at a different composition point, simplifying the overall separation process
3Productivity
If reactive distillation is used, then integration of reaction and distillation is achieved, but part of the dioxolane produced is lost due to discharge from the top of the purification column
Solution Approach 1:
The patent extracts the dioxolane loss problem by using a third component that forms a heterogeneous azeotrope with water, allowing complete dioxolane recovery in the bottom product without requiring discharge of the top product stream
Solution Approach 2:
The patent changes the azeotropic composition parameters by introducing nitroethane or nitromethane, which shifts the azeotrope formation to occur at conditions where dioxolane remains in the liquid phase, preventing its loss during the distillation process
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 high purity dioxolane production with minimal product loss and complete recycling of the extracting agent, ensuring stable and efficient operation on an industrial scale.
Implementation Method 1
reacting ethylene glycol and formaldehyde in the presence of at least one catalyst to form a raw product which comprises water, dioxolane and methanol
Implementation Method 2
transferring a distillate stream containing raw product from the top of the reaction distillation device to a phase separation unit, wherein an organic extracting agent is present in the phase separation unit
Implementation Method 3
transferring an organic fraction stream from the phase separation unit to an upper part of a purification column, withdrawing a bottom product stream containing dioxolane from the purification column
Implementation Method 4
transferring an aqueous fraction stream from the phase separation unit to a waste water column, withdrawing a waste water stream from the bottom of the waste water column
Data Source
AI summary
The present invention relates to a process for preparing dioxolane by reacting ethylene glycol with an aqueous solution of formaldehyde in the presence of an acid catalyst. The raw product comprising water, dioxolane and methanol is fed to a phase separation unit (20) wherein an organic extracting agent is present. An organic fraction stream from the phase separation unit is transferred to an upper part of a purification column (30) from which dioxolane is withdrawn as a bottom product while the distillate stream of the purification column is recycled to the phase separation unit. An aqueous fraction stream from the phase separation unit is transferred to a waste water column (40), withdrawing a waste water stream from the bottom of the waste water column, withdrawing a side stream (42) from a stage between the feed stage and the reflux stage of the waste water column and recycling this stream (42) to the phase separation unit, and withdrawing a distillate stream (43) containing methanol from the waste water column.