Olefin Conversion Process Using Isomerization and Metathesis
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Solution Overview
Problem
The decreasing demand for C5 olefins due to regulatory changes and the need to convert low-valued C5 streams into higher valued products like butenes and propylene, which are in increasing demand, particularly for the production of synthetic rubbers and chemical intermediates, is not effectively addressed by conventional processing methods.
Innovation Solution
A process involving the isomerization of alpha-pentenes to beta-pentenes, followed by metathesis with ethylene to produce butenes and propylene, with subsequent fractionation to separate these products, and an additional metathesis stage to convert propylene into ethylene and 2-butene, allowing for flexible production ratios of butenes to propylene.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional metathesis reactor with mixed catalysts is used to convert pentenes to propylene, then propylene production is achieved, but butadiene demand cannot be met and C5 olefin demand is decreasing
Solution Approach 1:
The conventional single-reactor mixed-catalyst system is segmented into two separate reactors: first reactor with isomerization catalyst to convert 1-pentene to 2-pentene, second reactor with metathesis catalyst to convert 2-pentene to propylene and butenes. This segmentation allows independent optimization of each reaction and enables flexible product distribution between propylene and butadiene.
Solution Approach 2:
The process enables dynamic adjustment of product ratios by controlling reaction conditions and catalyst selection in each reactor stage, allowing the system to adapt to varying market demands for propylene versus butadiene, thus providing operational flexibility.
2Productivity
If C5 olefins are converted to propylene via conventional metathesis, then propylene is produced, but ethylene consumption is high and value addition is limited
Solution Approach 1:
The isomerization step converts 1-pentene to 2-pentene before metathesis, creating a more reactive substrate that undergoes metathesis with ethylene to produce both propylene and butenes. This preliminary structural transformation enables more efficient ethylene utilization and diversifies products.
Solution Approach 2:
The process changes the molecular structure parameter of the pentene feedstock through isomerization (from terminal to internal double bond), which fundamentally alters the metathesis reaction pathway and product distribution, enabling simultaneous production of propylene and butenes with improved ethylene efficiency.
3Productivity
If steam cracking process is used to produce butadiene, then butadiene is obtained as byproduct, but separation complexity and energy consumption are high
Solution Approach 1:
The process uses 2-pentene as an intermediary compound that facilitates the formation of butadiene through metathesis reactions. Instead of directly cracking hydrocarbons to produce butadiene as a complex mixture requiring extensive separation, the controlled metathesis of 2-pentene with ethylene provides a more direct pathway with simpler product separation.
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 efficiently converts low-value C5 olefins into higher value butenes and propylene with minimal ethylene consumption, providing flexibility in managing olefins production and adapting to market demands.
Implementation Method 1
contacting a hydrocarbon mixture comprising alpha-pentenes with an isomerization catalyst to form an isomerization product comprising beta-pentenes
Implementation Method 2
contacting ethylene and the beta-pentenes with a first metathesis catalyst to form a first metathesis product comprising butenes and propylene
Implementation Method 3
fractionating the first metathesis product to for an ethylene fraction, a propylene fraction, a butene fraction, and a C5 fraction
Data Source
AI summary
A process for the production of C4 olefins, which may include: contacting a hydrocarbon mixture comprising alpha-pentenes with an isomerization catalyst to form an isomerization product comprising beta-pentenes; contacting ethylene and the beta-pentenes with a first metathesis catalyst to form a first metathesis product comprising butenes and propylene, as well as any unreacted ethylene and C5 olefins; and fractionating the first metathesis product to for an ethylene fraction, a propylene fraction, a butene fraction, and a C5 fraction.