Oligomerization Distillation for Olefin Purity
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Solution Overview
Problem
Existing oligomerization processes for C2 to C8 olefins face challenges in maintaining purity of starting olefins, leading to inhibition of reactions and by-product formation due to insufficient separation of oligomers, which increases investment costs with additional separation stages.
Innovation Solution
A process involving at least two reaction stages with distillation columns, where the last distillation column has a concentration of oligomers <100 ppm in the distillate, and a recycle-to-feed ratio between 0.1 and 5, allowing for efficient separation and reduced energy consumption by minimizing oligomer separation across all columns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple distillation columns are added to improve oligomer separation, then oligomer purity in distillate is improved, but investment costs increase
Solution Approach 1:
The patent applies partial action by requiring high oligomer separation only in the final distillation column of each reaction stage, while allowing earlier columns to operate with lower separation efficiency. The distillate from earlier columns contains oligomers (50-5000 ppm) which is acceptable because the critical purity requirement is met in the final column. This reduces the number of columns needed while maintaining product quality.
Solution Approach 2:
The patent segments the separation requirement across multiple reaction stages, where each stage has its own final distillation column that achieves the necessary purity. This distributed approach allows each column to be optimized for its specific function rather than requiring one large, complex separation system to handle all purification needs.
2Productivity
If olefin conversion is increased to improve productivity, then oligomer yield is improved, but oligomer contamination in distillate increases
Solution Approach 1:
The patent divides the conversion process into multiple reaction stages (at least two), each with its own distillation column. This segmentation allows each stage to operate at high conversion (60-95%) while the final column in each stage removes oligomers to meet purity specifications. The multi-stage approach distributes the separation burden and maintains both high productivity and distillate purity.
Solution Approach 2:
The patent implements a feedback mechanism where distillate from each reaction stage is recycled back to the reactor feed. This recycled stream contains unreacted olefins that can undergo further conversion in subsequent passes through the reactor, while the final distillation column ensures that any oligomers formed are removed before recycling. This feedback loop maintains high overall conversion while controlling oligomer contamination.
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 high olefin conversion with reduced investment costs by optimizing distillate purity and reflux, enabling efficient separation and energy savings in existing plants, and allows for the use of oligomer-free distillate as a synthetic raw material.
Implementation Method 1
the reaction mixture obtained from the at least one reactor is distilled in the at least one distillation column to separate the oligomers formed from the remaining reaction mixture, which contains at least the unreacted starting material olefins and which forms the distillate of the distillation column
Implementation Method 2
at least one reactor is subjected to oligomerization using a heterogeneous catalyst
Data Source
AI summary
The present invention relates to a process for the oligomerization of C2 to C8 olefins in at least two reaction stages, in which the reaction mixture is separated in the last distillation column in such a way that only very small amounts of the oligomers formed remain in the distillate.