Isobutene Purification via 1-Butene Isomerization and Rectification
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Solution Overview
Problem
Existing methods for purifying isobutene from a C4 stream face challenges in achieving high purity levels due to the close boiling points of isobutene and 1-butene, leading to high energy consumption and insufficient purity for certain applications.
Innovation Solution
A method involving an isomerization reactor with a hydrogenation-active catalyst on an aluminum oxide support converts 1-butene to 2-butene, followed by rectification columns to separate and enrich isobutene, using multiple catalytic isomerization and distillation steps to minimize 1-butene content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If distillation is used to separate isobutene from 1-butene, then separation is achieved, but energy consumption increases significantly due to close boiling points
Solution Approach 1:
The patent changes the chemical parameter of the C4 stream by converting 1-butene to 2-butene through catalytic isomerization, altering the boiling point characteristics to enable easier separation. This transforms the separation problem from a high-energy distillation process to a lower-energy process leveraging the greater boiling point difference between isobutene and 2-butene.
Solution Approach 2:
The patent introduces a catalyst as an intermediary substance that facilitates the isomerization reaction. The catalyst (comprising metal on support) acts as a mediator to convert 1-butene to 2-butene, enabling the separation process to proceed with lower energy input compared to direct distillation.
2Ease of operation
If 1-butene is isomerized to 2-butene to facilitate separation, then separation ease improves, but isobutene purity decreases due to 1-butene enrichment in the product stream
Solution Approach 1:
The patent segments the separation process into multiple stages: first isomerizing 1-butene to 2-butene, then performing distillation to separate isobutene from the enriched stream, and finally conducting a second isomerization step to convert remaining 1-butene. This multi-stage approach addresses the purity issue by breaking down the separation into manageable steps with intermediate purification.
Solution Approach 2:
The patent implements continuous isomerization and distillation operations where the process flow is maintained without interruption. The C4 stream undergoes continuous treatment through the catalyst bed and rectification column, ensuring consistent conversion of 1-butene to 2-butene and maintained purity of the isobutene product stream throughout the operation.
3Manufacturing precision
If repeated isomerization and fractionation are performed to increase isobutene purity, then purity improves, but energy consumption increases significantly
Solution Approach 1:
The patent performs preliminary isomerization of 1-butene to 2-butene before the main distillation separation. This preliminary action reduces the difficulty of the subsequent distillation process by creating a greater boiling point difference, thereby reducing the energy required for the main separation operation while still achieving high purity.
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
The process achieves isobutene purity of at least 95%, preferably 98%, and particularly 99%, by effectively reducing 1-butene levels through repeated isomerization and distillation, optimizing energy use and product purity.
Implementation Method 1
contacting the mass stream enriched with isobutane and isobutene and the hydrogen stream with the catalyst in the isomerization reactor, whereby 1-butene present in the mass stream enriched with isobutane and isobutene is isomerized to 2-butene
Implementation Method 2
feeding a product stream from the isomerization reactor, which contains proportionally less 1-butene than the mass stream enriched with isobutane and isobutene, into a rectification column
Data Source
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AI summary
The invention relates to a method for purifying isobutene from a C4 stream (7), which comprises at least 1-butene, 2-butene, isobutane and isobutene, comprising: isomerizing 1-butene of a material stream (12), which is obtained from the C4 stream (7) and is enriched in isobutane and isobutene, by means of a catalyst in an isomerization reactor (5) to obtain 2-butene; feeding a product stream (15) of the isomerization reactor (5) into a rectification column (6); and providing a material stream (18) enriched in isobutene by separating off said material stream (18) via a side draw (17) and/or as a bottoms product (19) of the rectification column (6) or by feeding a top product (16) of the rectification column (6), which top product is enriched in isobutane and contains isobutene in addition to the isobutane, to a second rectification column (24) in order to separate the isobutane from the isobutene and to obtain the material stream (18) enriched in isobutene in the bottoms product (26) of the second rectification column (24). The invention further relates to a process system (1a, 1b, 1c, 1d) for purifying isobutene from the C4 stream (7).