Catalytic Distillation for Isobutene Oligomerization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing oligomerization processes for producing isoolefins face challenges due to catalyst poisoning, fouling, and the formation of undesirable byproducts like C8 codimers, which reduce yield and increase costs associated with separation and purification.
Innovation Solution
A process involving a catalytic distillation reactor system that hydroisomerizes 1-butene to 2-butene, followed by oligomerization of isobutene in the presence of an oligomerization catalyst, with selective separation of isobutene and isobutane, minimizing the presence of linear butenes to reduce unwanted byproducts and enhance dimer selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional oligomerization processes are used to produce C8 dimers from mixed C4 olefins, then the target C8 dimer product can be obtained, but catalyst poisoning, fouling, and coking occur frequently due to impurities in the olefin feed stream, reducing catalyst activity and requiring frequent regeneration or replacement
Solution Approach 1:
The patent applies preliminary action by implementing a pre-treatment step before oligomerization that removes impurities (dienes, acetylenes, sulfur compounds) from the C4 olefin feed stream. This preliminary purification prevents catalyst poisoning and fouling during the oligomerization process, maintaining catalyst activity and productivity without frequent regeneration.
Solution Approach 2:
The patent uses an intermediary approach by introducing a selective catalyst system that first performs selective hydrogenation of dienes and acetylenes to olefins, then separates these converted components before the main oligomerization step. This intermediary treatment protects the oligomerization catalyst from poisoning while maintaining product yield.
2Productivity
If normal butene is present in the isobutene oligomerization feed to produce isooctene dimer, then the oligomerization reaction can proceed, but undesirable C8 codimers are formed, reducing the effective yield of the target C8 dimer product and increasing separation costs
Solution Approach 1:
The patent applies the extraction principle by implementing a selective separation step that removes normal butene from the C4 olefin feed stream before oligomerization. This extraction of the harmful component (normal butene) prevents it from participating in side reactions that form C8 codimers, thereby improving C8 dimer yield and reducing separation costs.
Solution Approach 2:
The patent uses local quality by employing different catalysts with specific selectivities for different functions: one catalyst selectively hydrogenates dienes/acetylenes while leaving normal butene unaffected, and another catalyst or separation step specifically targets normal butene removal. This localized selective treatment addresses the specific problem of C8 codimer formation without affecting the main oligomerization reaction.
3Manufacturing precision
If oligomerization reaction additives such as reaction moderators are added to increase dimer selectivity, then dimer selectivity is improved, but heavy oxygenates are formed through side reactions between the moderator and olefin or dimerization product, reducing yield and requiring additional separation
Solution Approach 1:
The patent converts the harmful effect of moderate reactivity (which causes heavy oxygenate formation) into a benefit by using the moderate as a dual-function agent: it provides necessary dimer selectivity control while the reaction conditions are optimized to minimize heavy oxygenate formation. The presence of the moderate is justified by the selectivity improvement, and the harmful side effect is managed through optimized reaction parameters.
Solution Approach 2:
The patent applies parameter changes by optimizing reaction conditions (temperature, pressure, catalyst composition, moderate-to-olefin ratio) to achieve the desired balance between dimer selectivity and heavy oxygenate formation. By adjusting these parameters, the system maintains high dimer selectivity while minimizing the formation of heavy oxygenates, reducing the need for additional separation steps.
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 increases the yield of the target C8 dimer product, reduces the formation of undesirable byproducts, and simplifies downstream separation processes, leading to cost savings and improved product purity.
Implementation Method 1
contacting the 1-butene with the hydrogen in the presence of the hydroisomerization catalyst to convert at least a portion of the 1-butene to 2-butene
Implementation Method 2
convert at least a portion of the 1-butene to 2-butene
Implementation Method 3
separating the isobutane and the isobutene from the n-butane and the 2-butene; recovering the isobutane and the isobutene from the catalytic distillation reactor system as an overheads fraction
Implementation Method 4
contacting the overheads fraction in an oligomerization reaction system with an oligomerization catalyst to convert a portion of the isobutene to oligomers
Data Source
AI summary
A process for oligomerization of isobutene, the process including: feeding a hydrocarbon stream comprising n-butane, 1-butene, 2-butene, isobutane, and isobutene to a catalytic distillation reactor system comprising a hydroisomerization catalyst; feeding hydrogen to the catalytic distillation reactor system; concurrently in the catalytic distillation reactor system: contacting the 1-butene with the hydrogen in the presence of the hydroisomerization catalyst to convert at least a portion of the 1-butene to 2-butene; separating the isobutane and the isobutene from the n-butane and the 2-butene; recovering the isobutane and the isobutene from the catalytic distillation reactor system as an overheads fraction; recovering the n-butane and the 2-butene from the catalytic distillation reactor system as a bottoms fraction; contacting the overheads fraction in an oligomerization reaction system with an oligomerization catalyst to convert a portion of the isobutene to oligomers.