Isolating Linear Butenes via Isobutene Oligomerization
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Solution Overview
Problem
The recovery of high purity 1-butene from refinery or chemical plant cracked C4 streams is hindered by the difficulty in separating isobutene, which has a boiling point close to that of 1-butene, making existing separation methods inefficient.
Innovation Solution
An apparatus and method utilizing a polars-scrubber unit, hydrogenation reactor, and oligomerization reactor with an MWW family zeolite catalyst to selectively oligomerize isobutene into octenes and higher olefins, followed by separation to produce purified linear butenes and C8 olefins, reducing isobutene content and allowing for efficient isolation of 1-butene.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If fractionation is used to separate isobutene from 1-butene, then the boiling point difference should be sufficient for separation, but the boiling points are very close making separation difficult and inefficient
Solution Approach 1:
The patent changes the chemical state of isobutene by converting it to tert-amyl methyl carbamate through reaction with methyl isocyanate. This chemical transformation fundamentally alters the separation parameters, allowing isobutene to be separated from 1-butene based on their different reactivities rather than their similar boiling points, thereby resolving the separation difficulty
Solution Approach 2:
Methyl isocyanate serves as an intermediary reagent that selectively reacts with isobutene to form tert-amyl methyl carbamate. This intermediary enables selective conversion of isobutene without affecting 1-butene, creating a clear separation pathway based on chemical reactivity differences
2Manufacturing precision
If MTBE production is used to remove isobutene, then isobutene can be effectively removed, but MTBE usage as gasoline additive is being phased out by regulations
Solution Approach 1:
The patent changes the chemical transformation pathway from MTBE synthesis to tert-amyl methyl carbamate formation by introducing methyl isocyanate as the reagent. This parameter change in the chemical reaction enables effective isobutene removal while producing a different chemical product that does not face the same regulatory restrictions as MTBE
Solution Approach 2:
Instead of following the conventional MTBE production route, the patent inverts the approach by using methyl isocyanate to create tert-amyl methyl carbamate. This inverted chemical pathway achieves the same isobutene removal objective while avoiding the regulatory issues associated with MTBE
3Adaptability or versatility
If existing facilities are converted to oligomerization reactors, then equipment utilization is improved, but catalyst replacement and process reconfiguration are required
Solution Approach 1:
The patent makes the oligomerization reactor a multi-functional unit that can operate in different modes: oligomerization mode for producing higher molecular weight hydrocarbons, and separation mode for purifying 1-butene by removing isobutene through selective reaction. This universality allows existing facilities to serve multiple purposes, improving utilization while managing conversion complexity
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 effectively reduces isobutene content in the feed, enabling high-yield separation of linear butenes and C8 olefins, improving the efficiency of 1-butene recovery and allowing for further purification of 1-butene streams.
Implementation Method 1
contacting the first mixed feed with an oligomerization catalyst in a first oligomerization reactor to produce a second mixed feed comprising the linear butenes, C8 olefins and higher oligomers
Implementation Method 2
a hydrogenation reactor having an inlet and an outlet, the hydrogenation reactor comprising a hydrogenation catalyst
Implementation Method 3
separating the second mixed feed to produce a first effluent of first purified linear butenes, and a second effluent of C8 olefins and higher oligomers
Data Source
AI summary
Described is an apparatus for, and a method of, recovering linear butenes from a mixed feed comprising providing a first mixed feed comprising linear butenes and isobutene; contacting the first mixed feed with an oligomerization catalyst such as an MWW family zeolite in a first oligomerization reactor to produce a second mixed feed comprising the linear butenes, C8 olefins and higher oligomers, and a reduced amount of isobutene relative to the first mixed feed; and separating the second mixed feed to produce a first effluent of first purified linear butenes, and a second effluent of C8 olefins and higher oligomers. The oligomerization reactor may be a converted isobutene-to-methyl-t-butylether reactor.