Propylene Oxide Production via Reactive Distillation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current industrial processes for propylene oxide production, such as the chlorohydrin and hydroperoxide processes, face issues like formation of undesirable by-products, propensity for decomposition, and costly purification procedures, with no commercialized direct oxidation process available, and previous peracetic acid epoxidation techniques suffer from instability at high temperatures due to poor temperature control.
Innovation Solution
A continuous epoxidation process using peracetic acid in a reactive distillation column, where propylene and peracetic acid react simultaneously with a homogeneous catalyst, allowing for the recovery of high purity propylene oxide and acetic acid, with a pre-reactor optionally used to increase residence time and minimize decomposition, and the solvent ethyl acetate is recycled for energy savings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If peracetic acid epoxidation is performed at high temperature to increase reaction rate, then productivity is improved, but peracetic acid decomposes and selectivity deteriorates
Solution Approach 1:
The patent changes the temperature parameter from high to low range (0-100°C, preferably 10-50°C) to maintain peracetic acid stability while achieving acceptable reaction rates through extended reaction time and efficient mass transfer in the reactive distillation column
Solution Approach 2:
The patent performs preliminary action by pre-mixing peracetic acid with propylene before introducing to the reactive distillation column, ensuring proper contact and reaction conditions from the start, which prevents decomposition while maintaining productivity
2Manufacturing precision
If conventional separate reaction and distillation processes are used, then manufacturing precision is maintained, but device complexity and capital costs increase
Solution Approach 1:
The patent merges the reaction and distillation operations into a single reactive distillation column, where propylene and peracetic acid react to form propylene oxide while simultaneously distilling the product as it forms. This integration maintains manufacturing precision through continuous separation while reducing device complexity by eliminating separate reactors and distillation columns
Solution Approach 2:
The reactive distillation column performs multiple functions simultaneously: it acts as both a reaction vessel and a distillation column, enabling both chemical transformation and product separation in one unit operation, thereby reducing overall process complexity while maintaining product purity
3Object-generated harmful factors
If peracetic acid is used as oxidant for direct epoxidation, then harmful by-products are reduced, but temperature control becomes difficult leading to hot spots
Solution Approach 1:
The patent changes the temperature parameter from high to low range (0-100°C, preferably 10-50°C) to prevent hot spots and maintain temperature control while using peracetic acid as oxidant, thereby reducing by-product formation and improving process safety
Solution Approach 2:
The patent introduces an inert solvent as an intermediary medium to dissolve peracetic acid and facilitate heat transfer, preventing localized overheating and hot spots while maintaining effective oxidation reactions
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 reduces capital equipment costs, minimizes by-product formation, and efficiently recovers high purity propylene oxide, achieving higher selectivity and yield while avoiding hot spots through the use of a reactive distillation column, which integrates reaction and distillation, and stabilizes peracetic acid with a metal ion catalyst.
Implementation Method 1
reacting the propylene and peracetic acid to form propylene oxide in the presence of a homogeneous catalyst and recovering a mixture containing propylene oxide, acetic acid and solvent as a bottoms fraction from the bottom zone; introducing the mixture into a first distillation zone, from which an acetic acid rich stream is recovered from the bottom and a propylene oxide rich stream is recovered from the overhead
Implementation Method 2
reacting propylene with peracetic acid to form propylene oxide
Implementation Method 3
reacting the propylene and peracetic acid to form propylene oxide in the presence of a homogeneous catalyst
Data Source
AI summary
A continuous epoxidation process for the production of high purity propylene oxide by the reaction of propylene with an oxidant that is a per-acid, such as peracetic acid (PAA), in a reactive distillation (RD) column. The RD column provides excellent heat integration and temperature control, and the process has the advantage of lower investment cost for capital equipment. The process operates at mild temperatures and pressures. A ferric acetylacetonate homogeneous catalyst and/or stabilizer may be included as part of the PAA feed to the process to increase PAA conversion and selectivity to propylene oxide. A pre-reactor can be incorporated upsteam of the RD column to increase the residence time at lower temperatures to enhance productivity.