Ethylene Dimerization and Metathesis for Propylene Yield
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Solution Overview
Problem
Current processes for producing propylene and 1-butene from ethylene often result in excessive formation of gasoline components and suboptimal yields of propylene, making it difficult to meet market demands.
Innovation Solution
A process involving the dimerization of ethylene in the presence of a dimerization catalyst to produce a mixture of 1-butene and 2-butenes, followed by distillation and subsequent metathesis reaction with ethylene in the presence of a metathesis catalyst to enhance propylene production, while minimizing the formation of heavier olefins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ethylene is dimerized to produce 1-butene and 2-butenes, then propylene yield is improved, but gasoline components are excessively formed
Solution Approach 1:
The process is divided into three distinct segments: (1) dimerization of ethylene to produce 1-butene and 2-butenes, (2) separation of the dimerization mixture into C4 stream and heavy stream, and (3) metathesis reaction of 2-butenes with ethylene to produce propylene. This segmentation allows selective optimization of each step to maximize propylene yield while minimizing gasoline component formation.
Solution Approach 2:
The heavy stream containing gasoline components (C5+ olefins) is extracted and separated from the C4 stream through distillation. By removing these heavier components early in the process, their further formation through unwanted reactions is minimized, while the C4 stream is directed toward productive metathesis reactions for propylene synthesis.
2Productivity
If 1-butene reacts with 2-butene to form 2-pentene and 3-hexene, then metathesis reaction occurs, but heavier olefins are produced
Solution Approach 1:
The metathesis catalyst is selectively applied only to the C4 stream containing 2-butenes and ethylene, creating a localized reaction zone with controlled selectivity. This ensures that metathesis reactions occur primarily between C4 olefins and ethylene to produce propylene, rather than allowing uncontrolled polymerization or oligomerization that would generate heavier olefins.
Solution Approach 2:
The process utilizes specific temperature and pressure parameters in the metathesis reactor, along with selective catalyst composition, to favor propylene formation over heavier olefin production. By optimizing these parameters, the reaction selectivity is tuned to maximize C3 products while suppressing C5+ formation.
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 increases the yield of propylene and reduces the production of gasoline components, allowing for better market demand fulfillment by optimizing the separation and conversion of ethylene and butene streams.
Implementation Method 1
dimerizing ethylene in the presence of a dimerization catalyst to produce a dimerization mixture comprising 1-butene and 2-butenes
Implementation Method 2
The dimerization mixture is distilled to produce a 1-butene stream containing 1-butene and unreacted ethylene, a 2-butenes stream, and a heavy stream
Implementation Method 3
reacting the 2-butenes stream with ethylene in the presence of a metathesis catalyst to produce a metathesis mixture comprising propylene, ethylene, and 2-butenes
Data Source
AI summary
A process for producing propylene and 1-butene is disclosed. The process comprises dimerizing ethylene in the presence of a dimerization catalyst to produce a dimerization mixture comprising 1-butene and 2-butenes. The dimerization mixture is distilled to produce a 1-butene stream containing 1-butene and ethylene, a 2-butenes stream, and a heavy stream. The 2-butenes stream is reacted with ethylene in the presence of a metathesis catalyst to produce a metathesis mixture comprising propylene, ethylene, and 2-butenes. Propylene is separated from the metathesis mixture.