Trioxane Purification Process Using Membrane Dehydration and Recycling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing trioxane synthesis processes face challenges in achieving ultra-pure trioxane due to the presence of impurities like formaldehyde, formic acid, and water, leading to equipment corrosion, blockages, and high energy consumption, with current separation methods failing to produce 100%-pure trioxane efficiently.
Innovation Solution
A process involving oxidation of methanol and methylal to form formaldehyde, followed by cyclization with a solid acidic catalyst, catalytic refinement to convert impurities into methanol, and membrane pervaporation for dehydration, combined with reactive distillation to separate and recycle components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional rectification and extraction methods are used to separate trioxane from impurities, then separation is achieved, but ultra-pure trioxane (100% purity) cannot be obtained and energy consumption increases
Solution Approach 1:
The patent employs a multi-stage rectification process with varying pressures and temperatures to selectively separate different impurities. The first rectification tower operates at one set of parameters to remove low-boiling impurities, while the second tower uses different parameters for high-boiling impurities, achieving ultra-purity without excessive energy consumption
Solution Approach 2:
The separation process is divided into multiple independent stages: extraction to remove formaldehyde, first rectification for low-boiling impurities, second rectification for high-boiling impurities, and crystallization. Each stage targets specific impurities, making the overall process energy-efficient while achieving 100% purity
2Manufacturing precision
If multiple separation steps including extraction with benzene are used, then impurity removal is improved, but the separation system becomes more complicated and diluted formaldehyde solution recovery becomes difficult
Solution Approach 1:
The patent integrates the extraction tower to serve multiple functions: removing formaldehyde impurities, concentrating trioxane, and preparing the solution for subsequent rectification steps. This multi-functionality reduces the need for separate dedicated units for each operation, simplifying the overall system
Solution Approach 2:
Benzene is used as an intermediary extracting agent that selectively binds with formaldehyde impurities. After extraction, the benzene-formaldehyde complex is easily separated, and benzene is recovered for reuse. This intermediary approach simplifies the removal of difficult-to-separate impurities without requiring complex equipment
3Productivity
If conventional synthesis and separation processes are used, then trioxane is produced, but formic acid corrosion and pipeline blockages occur due to impurities
Solution Approach 1:
The patent performs preliminary removal of formaldehyde impurities through extraction before the main rectification process. By eliminating formaldehyde early, subsequent polymerization reactions that cause pipeline blockages are prevented, ensuring reliable operation throughout the production process
Solution Approach 2:
The patent converts potentially harmful formic acid impurities into removable components through the rectification process. By carefully controlling temperature and pressure gradients, formic acid is separated and removed, preventing corrosion while maintaining high productivity
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 high-purity trioxane with reduced impurities, avoids equipment corrosion, and lowers energy consumption by recycling materials, improving separation efficiency and reducing pipeline blockages.
Implementation Method 1
oxidation of methanol and methylal to form formaldehyde
Implementation Method 2
cyclization with a solid acidic catalyst
Implementation Method 3
membrane pervaporation for dehydration
Implementation Method 4
subjected to extraction and rectification
Data Source
AI summary
A process for preparing trioxane from methanol includes: step 1: subjecting a mixture of methanol and methylal to a reaction to obtain formaldehyde, and absorbing the formaldehyde with water to obtain a concentrated formaldehyde aqueous solution; step 2: subjecting the concentrated formaldehyde aqueous solution to cyclization to obtain a mixture containing trioxane, and passing the mixture through a trioxane concentration tower to obtain a crude trioxane product; step 3: converting a by-product and unreacted formaldehyde in the crude trioxane product into methanol, conducting dehydration through a membrane dehydration process, and subjecting a retentate to dealcoholization to obtain purified trioxane; and step 4: subjecting the remaining streams to reactive distillation to obtain a mixture of methanol and methylal at a top- and water at a bottom of the reactive distillation tower; returning the mixture of methanol and methylal to step 1; and returning or discharging the water.