1-Butene Recovery from C4 Mixtures via Isobutene Conversion
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Solution Overview
Problem
Current methods for obtaining high-purity 1-butene from C4 hydrocarbon mixtures are inefficient due to the proximity of boiling points, leading to suboptimal recovery rates and increased costs, especially with the decline of MTBE production and the need for alternative processes that maintain isobutene conversion levels.
Innovation Solution
A process involving double-stage isobutene conversion through etherification or dimerization with additional distillation and selective hydrogenation stages, followed by further conversion and distillation to enhance 1-butene recovery, utilizing multiple reactors and distillation columns to achieve high purity and productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If simple distillation is used to separate 1-butene from C4 hydrocarbon mixtures, then the separation process is simple, but the separation efficiency is poor due to close boiling points
Solution Approach 1:
The separation process is divided into multiple sequential distillation columns (dephlegmator, main fractionation column, rectification column, stripping column) rather than attempting single-stage separation. Each column performs a specific separation function, progressively purifying 1-butene from the C4 mixture despite close boiling points.
Solution Approach 2:
The process moves from simple thermal distillation to a multi-dimensional separation approach by combining distillation with selective hydrogenation. The hydrogenation step converts 2-butenes to 1-butene, creating an additional separation dimension that exploits chemical transformation rather than just physical property differences.
2Productivity
If multiple distillation columns and conversion stages are added to improve 1-butene recovery, then the purity and recovery rate increase, but the device complexity increases
Solution Approach 1:
The process merges conversion and separation functions into an integrated flow. The dephlegmator removes light ends (C3, isobutane) before the main fractionation column, and the stripping column removes heavy ends (n-butane, C5) after the rectification column. This merging of preliminary and final separation steps with the main distillation process improves overall recovery while managing complexity through functional integration.
Solution Approach 2:
Selective hydrogenation of 2-butenes to 1-butene is performed as a preliminary action before the final rectification and stripping stages. This pre-conversion ensures that maximum yield of 1-butene is achieved before the final separation steps, improving overall recovery rate while allowing the subsequent columns to operate more efficiently.
3Reliability
If isobutene conversion is maintained at high levels through etherification, then isobutene removal is effective, but the process becomes less flexible with declining MTBE production
Solution Approach 1:
The process changes the operational parameters of the distillation columns to accommodate varying feed compositions and product specifications. By adjusting reflux ratios, column temperatures, and flow rates, the system can maintain high 1-butene recovery and purity even when isobutene conversion levels or market demands for MTBE fluctuate, providing operational flexibility.
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 significantly increases the recovery of high-purity 1-butene while maintaining isobutene conversion levels, overcoming the limitations of existing technologies and adapting to changing market demands by improving operational flexibility and product quality.
Implementation Method 1
etherification reaction with methanol is used, with the formation of methyl tert-butyl ether (MTBE)
Implementation Method 2
simple distillation, due to the closeness of boiling point
Implementation Method 3
Relative VolatilityB.P., OC
Implementation Method 4
selective hydrogenation to linear butenes
Data Source
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AI summary
A process is described for obtaining high-purity 1-butene starting from C4 hydrocarbon mixtures containing isobutene, n-butane, isobutane, 1, 3 -butadiene, 1-butene, 2- butenes and also optionally C3 and C5 hydrocarbons, comprising the following stages: conversion of isobutene effected in a double stage, wherein each stage consists of one or more reactors followed by a distillation column for the recovery of the reaction product; recovery of the excess alcohol; recovery of 1-butene using at least two distillation columns; characterised in that it also uses a further conversion stage, consisting of one or more reactors in series, for completing the isobutene removal.