MTBE Raffinate Propylene Production via Isomerization
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Solution Overview
Problem
The majority of C4 byproduct streams from steam crackers are underutilized, with only butadiene and isobutylene being effectively collected and used, while the remaining C4 byproducts, such as n-butane, isobutane, 1-butene, and 2-butene, are often wasted in MTBE production processes.
Innovation Solution
The method involves using the MTBE synthesis raffinate as a feed stream, separating n-butane and isobutane from it using a molecular sieve, and then isomerizing 1-butene to increase the concentration of 2-butene, which is subsequently reacted with ethylene to produce propylene, enhancing the efficiency of propylene production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If MTBE synthesis raffinate is used as low-value Liquefied Petroleum Gas, then the process is simple, but the utilization rate of C4 byproducts is low and valuable propylene is lost
Solution Approach 1:
The patent changes the chemical composition parameters of the feed stream by separating n-butane and isobutane from the MTBE synthesis raffinate before metathesis reaction. This parameter change enables the metathesis catalyst to work more efficiently and increases propylene yield from the C4 byproducts that would otherwise be wasted
Solution Approach 2:
The patent recovers valuable propylene from what would have been discarded low-value Liquefied Petroleum Gas. By implementing metathesis reaction with ethylene on the raffinate stream, the process transforms waste C4 hydrocarbons into high-value propylene product
2Device complexity
If MTBE synthesis raffinate is directly used in metathesis reaction, then the process is simple, but the catalyst productivity is low due to presence of n-butane and isobutane
Solution Approach 1:
The patent extracts n-butane and isobutane from the MTBE synthesis raffinate stream using a molecular sieve adsorber before the metathesis reaction. This removal of paraffins prevents catalyst deactivation and maintains high catalyst productivity throughout operation
Solution Approach 2:
The patent performs preliminary separation of n-butane and isobutane from the feed stream before metathesis reaction. This preliminary action prepares the feed stream by removing components that would otherwise poison the catalyst, ensuring optimal catalyst performance
3Device complexity
If 1-butene is not isomerized to 2-butene, then the process is simpler, but the propylene production efficiency is lower
Solution Approach 1:
The patent changes the isomeric composition parameter of the butene stream by isomerizing 1-butene to 2-butene. This parameter change increases the concentration of 2-butene which reacts more efficiently in metathesis to produce propylene, thereby improving production efficiency
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 utilization rate of C4 byproducts, improves propylene production efficiency, and reduces waste by converting the MTBE synthesis raffinate into a higher-value propylene product.
Implementation Method 1
flowing a methyl tertiary butyl ether synthesis raffinate stream that comprises C4 hydrocarbons through a molecular sieve so that the molecular sieve separates the MTBE synthesis raffinate into a stream comprising primarily n-butane and isobutane
Implementation Method 2
the stream comprising primarily 1-butene and 2-butene is distilled to produce a first stream, comprising primarily 1-butene and 2-butene, collectively, and a first 2-butene stream, comprising primarily 2-butene
Implementation Method 3
The 1-butene in the first stream is isomerized to form a second 2-butene stream comprising primarily 2-butene
Implementation Method 4
reacting 2-butene of the second 2-butene stream and 2-butene of the first 2-butene stream with ethylene to produce the propylene
Data Source
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AI summary
Systems and methods for producing propylene using an MTBE synthesis raffinate are disclosed. An MTBE synthesis raffinate stream first passes through a molecular sieve to separate n-butane and isobutane from the rest of C4 hydrocarbons of the MTBE synthesis raffinate. The 1-butene in the rest of C4 hydrocarbons of the MTBE synthesis raffinate is then isomerized to form 2-butene. Therefore, the concentration of 2-butene in the subsequent propylene production process increases due to the separation of n-butane and isobutane and the isomerization of 1-butene, resulting in an improved reaction rate and reaction efficiency for propylene production.