Propylene Oxide Process Absorption Recycling
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Solution Overview
Problem
Propylene oxide produced by direct oxidation often reacts with solvents to form unwanted byproducts such as propylene glycol and propylene glycol ethers, reducing the efficiency and selectivity of the process.
Innovation Solution
A process involving the reaction of propylene, oxygen, and hydrogen in a slurry comprising a transition metal zeolite and noble metal catalyst, with a solvent and buffer, to produce propylene oxide, where the gaseous product stream is contacted with an absorbent to recycle and reduce propylene oxide decomposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If propylene oxide is produced by direct oxidation in a solvent, then propylene oxide can be formed, but propylene oxide reacts with the solvent to form unwanted byproducts such as propylene glycol and propylene glycol ethers
Solution Approach 1:
The patent extracts propylene oxide from the reaction mixture by flashing the reaction product to separate vapor and liquid phases, then absorbing propylene oxide into a methanol/water liquid in an absorber. This removes propylene oxide from the reactive slurry environment, preventing further reaction with the solvent to form glycol byproducts.
Solution Approach 2:
The patent performs preliminary separation of propylene oxide from the reaction mixture through flashing and absorption before byproducts can form. By removing propylene oxide from the reaction zone and recycling unreacted gases, the process prevents subsequent unwanted reactions with the solvent.
2Productivity
If propylene oxide is recycled to the reaction system, then unreacted propylene can be reused, but propylene oxide may decompose or react further to form unwanted products
Solution Approach 1:
The patent extracts propylene oxide from the gas phase by contacting the gaseous product stream with an absorbent (methanol/water liquid) to produce a liquid effluent containing propylene oxide and a gas effluent that is recycled. This separation prevents propylene oxide from being exposed to reaction conditions during recycling.
Solution Approach 2:
The patent introduces an absorbent (methanol/water liquid) as an intermediary to transfer propylene oxide from the gaseous product stream to the liquid phase. This intermediary process allows selective removal of propylene oxide while enabling recycling of unreacted propylene and other gases without exposing propylene oxide to decomposition conditions.
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 effectively minimizes the formation of byproducts like propylene glycol and improves the selectivity and efficiency of propylene oxide production by recycling the gas effluent, thereby enhancing the overall propylene oxide yield and reducing undesired reactions.
Implementation Method 1
The gaseous product stream is contacted with an absorbent to produce a gas effluent and a liquid effluent
Implementation Method 2
reacting propylene, oxygen, and hydrogen in a slurry comprising a catalyst and a solvent to produce a gaseous product stream and a liquid product stream
Implementation Method 3
direct oxidation of propylene with oxygen and hydrogen in a solvent in the presence of a catalyst
Data Source
AI summary
A process for making propylene oxide from propylene is disclosed. Propylene, hydrogen, and oxygen are reacted in a slurry comprising a catalyst and a solvent to produce a gaseous product stream and a liquid product stream. The gaseous product stream is contacted with an absorbent to produce a gas effluent and a liquid effluent. The gas effluent is recycled to the reaction step.