Staged Metathesis Process for Butene Conversion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing propylene production processes face limitations in conversion rates due to factors like limited recycle rates, especially in metathesis reactions involving butene and ethylene, which restrict the efficient production of propylene.
Innovation Solution
A staged metathesis process involving a first and second metathesis reaction, where a metathesis feed stream containing butene is reacted with ethylene in the presence of metathesis catalysts, followed by separation and recycling, to enhance propylene production efficiency, including the use of isomerization catalysts like magnesium oxide and varying ethylene:butene ratios in each reaction stage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single-stage metathesis reaction is used to produce propylene from butene and ethylene, then the process is simple to operate, but the butene conversion rate is limited
Solution Approach 1:
The single-stage metathesis reaction is divided into two sequential stages. The first metathesis reactor performs the initial conversion of butene to propylene, and the second metathesis reactor further converts the remaining butene and intermediate products. This segmentation allows each reactor to be optimized for specific conversion conditions, achieving over 85% total butene conversion while maintaining reasonable process complexity through modular design.
2Productivity
If recycle rates are increased to improve butene conversion, then propylene production efficiency improves, but the process complexity and operational difficulty increase
Solution Approach 1:
The process performs preliminary separation of propylene from the first metathesis reactor effluent before the second reaction stage. This preliminary action prevents propylene from interfering with the second metathesis reaction and allows the second reactor to focus on converting remaining butene and C5+ olefins, improving overall efficiency without requiring complex continuous recycling operations.
Solution Approach 2:
The separation unit acts as an intermediary between the two metathesis reactors. It removes propylene and some ethylene from the first reactor effluent, creating a optimized feed composition for the second reactor. This intermediary step simplifies operational control by decoupling the two reaction stages while maintaining high overall conversion.
3Manufacturing precision
If a single-stage metathesis process is used, then the process configuration is simple, but selectivity is reduced and higher co-product olefins are formed
Solution Approach 1:
Each metathesis reactor is configured with specific catalysts and operating conditions optimized for its particular function. The first reactor uses conditions favoring initial butene conversion, while the second reactor is optimized for converting remaining butene and C5+ olefins. This local optimization of reaction conditions in each stage improves overall selectivity and reduces unwanted higher co-product olefins compared to a single-stage 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
This approach achieves a total butene conversion of at least 85% and improves selectivity by tailoring each reaction stage, reducing higher co-product olefins and enhancing overall propylene recovery compared to single-stage processes.
Implementation Method 1
reacting a metathesis feed stream including butene with ethylene in the presence of a first metathesis catalyst via a first metathesis reaction
Implementation Method 2
the process further includes reacting the corresponding metathesis feed stream with ethylene in the presence of an isomerization catalyst
Implementation Method 3
separating at least a portion of the propylene and ethylene from the first metathesis product stream to form a first overhead stream and to form a first de-propenized bottoms stream
Data Source
Figure 1
AI summary
Processes for forming propylene are described herein. The processes generally include reacting a metathesis feed stream including butene with ethylene in the presence of a first metathesis catalyst via a first metathesis reaction to form a first metathesis product stream including propylene, ethylene, butene, and C5+ olefins; separating at least a portion of the propylene and ethylene from the first metathesis product stream to form a first overhead stream and to form a first de-propenized bottoms stream including butene and C5+ olefins; reacting at least a portion of the first de-propenized bottoms stream with ethylene in the presence of a second metathesis catalyst via a second metathesis reaction to form a second metathesis product stream including propylene, ethylene, butene, and C5+ olefins; and separating at least a portion of the propylene and ethylene from the second metathesis product stream to form a second overhead stream; and recovering propylene from the first overhead stream, the second overhead stream or combinations thereof.