C5 Olefin Purification via Cyclopentadiene Dimerization and Catalytic Distillation
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Solution Overview
Problem
Steam cracker C5 hydrocarbon streams contain high concentrations of cyclopentadiene and dicyclopentadiene, leading to catalyst fouling and runaway reactions when processed similarly to FCC C5 products, and sulfur compounds can inhibit catalyst performance, requiring effective methods to separate and hydrogenate these impurities while minimizing olefin loss.
Innovation Solution
A process involving dimerization of cyclopentadiene to form dicyclopentadiene, followed by fractionation and selective hydrogenation in a catalytic distillation reactor system with multiple catalyst zones, using nickel-based and palladium-based catalysts to separate and convert C5 dienes to C5 olefins, with a saturated hydrocarbon diluent and hydrogen, while recycling cyclopentane to control cyclopentene levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If steam cracker C5 hydrocarbon streams are processed similarly to FCC C5 products through selective hydrogenation, then dienes and acetylenes can be removed, but catalyst fouling and runaway reactions occur due to high concentrations of cyclopentadiene and dicyclopentadiene
Solution Approach 1:
The patent applies preliminary action by dimerizing cyclopentadiene to form dicyclopentadiene in a first reactor before the hydrogenation step. This pre-treatment removes the problematic cyclopentadiene that would otherwise cause catalyst fouling and runaway reactions during hydrogenation, while preserving the desired C5 olefins for subsequent processing
Solution Approach 2:
The patent segments the processing into distinct stages: (1) dimerization of cyclopentadiene in a first reactor, (2) fractionation to separate C6+ hydrocarbons and dicyclopentadiene, and (3) selective hydrogenation of remaining dienes in a second reactor. This segmentation allows each step to be optimized independently, preventing catalyst fouling while achieving effective impurity removal
2Device complexity
If simple fractionation is used to separate C5 olefins from impurities, then the process complexity is reduced, but high rates of catalyst fouling and potential runaway reactions occur
Solution Approach 1:
The patent introduces a preliminary dimerization step that converts cyclopentadiene to dicyclopentadiene before hydrogenation. This simple additional step effectively eliminates the source of catalyst fouling and runaway reactions, achieving reliable catalyst operation without complex processing equipment
Solution Approach 2:
The patent extracts the problematic cyclopentadiene component through dimerization into dicyclopentadiene, which is then separated by fractionation. This extraction removes the harmful substance that causes catalyst fouling, allowing the remaining stream to be safely hydrogenated with stable catalyst performance
3Manufacturing precision
If selective hydrogenation is performed to remove dienes and acetylenes, then olefin product quality is improved, but significant loss of useful olefin materials occurs
Solution Approach 1:
The patent performs preliminary dimerization of cyclopentadiene before hydrogenation, converting it to dicyclopentadiene which is then separated by fractionation. This removes the need to hydrogenate cyclopentadiene, preventing the formation of cyclopentene that would otherwise be lost or require additional removal steps, thereby reducing olefin material loss while maintaining product quality
Solution Approach 2:
The patent changes the chemical form of cyclopentadiene through dimerization, transforming it from a monomer that would consume hydrogen and potentially form unwanted cyclopentene into a dimer (dicyclopentadiene) that can be easily separated by fractionation. This parameter change eliminates the source of olefin loss while achieving the desired purification
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 reduces diene content, maximizes olefin recovery, and stabilizes catalyst performance, achieving high diene conversion and olefin recovery rates with reduced olefin loss and catalyst deactivation, suitable for producing propylene from steam cracker C5 feeds.
Implementation Method 1
cyclopentadiene is dimerized to form dicyclopentadiene
Implementation Method 2
at least a portion of the C5 dienes are selectively hydrogenated to form additional C5 olefins
Implementation Method 3
the linear C5 olefins are separated from the cyclic C5 olefins and C5 dienes contained in the second fraction
Data Source
AI summary
Producing C5 olefins from steam cracker C5 feeds may include reacting a mixed hydrocarbon stream comprising cyclopentadiene, C5 olefins, and C6+ hydrocarbons in a dimerization reactor where cyclopentadiene is dimerized to dicyclopentadiene. The dimerization reactor effluent may be separated into a fraction comprising the C6+ hydrocarbons and dicyclopentadiene and a second fraction comprising C5 olefins and C5 dienes. The second fraction, a saturated hydrocarbon diluent stream, and hydrogen may be fed to a catalytic distillation reactor system for concurrently separating linear C5 olefins from saturated hydrocarbon diluent, cyclic C5 olefins, and C5 dienes contained in the second fraction and selectively hydrogenating C5 dienes. An overhead distillate including the linear C5 olefins and a bottoms product including cyclic C5 olefins are recovered from the catalytic distillation reactor system. Other aspects of the C5 olefin systems and processes, including catalyst configurations and control schemes, are also described.