Stable Facilitated Transport Membranes for Olefin Separation
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Solution Overview
Problem
Current membrane technologies for olefin/paraffin separations, such as propylene/propane and ethylene/ethane, face challenges with low selectivity and stability due to the trade-off between permeability and selectivity, and existing facilitated transport membranes suffer from chemical instability and high costs.
Innovation Solution
Development of a stable high-performance facilitated transport membrane with an asymmetric integrally-skinned polymeric structure, featuring a hydrophilic polymer like chitosan or sodium alginate and a metal salt like silver nitrate, which enhances CO2 permeance and selectivity, and incorporates these polymers into the membrane's thin, dense skin layer to fix metal cations, improving olefin/paraffin selectivity and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If facilitated transport membranes with metal ions are used to achieve high olefin/paraffin separation selectivity, then separation selectivity is improved, but chemical stability deteriorates due to carrier poisoning or loss
Solution Approach 1:
The patent employs a porous support membrane structure that provides mechanical stability and structural integrity to the facilitated transport membrane. The porous framework prevents collapse and maintains the membrane's architectural stability during operation, thereby improving chemical stability while preserving the metal ion complexation sites needed for high separation selectivity.
Solution Approach 2:
The patent creates a composite membrane system combining a porous support membrane with facilitated transport functionality. This composite structure integrates the mechanical stability of the porous support with the separation selectivity of metal ion complexes, resolving the contradiction between chemical stability and separation performance by distributing functions across different material components.
2Reliability
If conventional polymer membranes are used for olefin/paraffin separation, then chemical stability is improved, but separation selectivity and permeability deteriorate due to the polymer upper bound limit
Solution Approach 1:
The patent introduces metal ions as intermediary species that mediate the separation process. These metal ions form reversible complexes with olefin pi bonds, acting as selective binding sites that enhance separation selectivity beyond what conventional polymer matrices can achieve alone, while the polymer support maintains chemical stability.
Solution Approach 2:
The patent changes the separation mechanism from purely physical diffusion through polymer matrices to chemical complexation via metal ions. This parameter change in the separation mechanism allows overcoming the polymer upper bound limit by introducing specific chemical interactions between metal cations and olefin molecules, thereby achieving higher selectivity and permeability.
3Measurement precision
If metal ions are incorporated into porous support membranes to form facilitated transport membranes, then olefin/paraffin separation selectivity is improved, but metal cation loss increases under feed pressure
Solution Approach 1:
The patent converts the potential harm of metal cation loss under pressure into a benefit by designing a system where metal ions are stably anchored within the porous support structure. The porous framework provides physical confinement and stabilization, preventing metal cation leaching while maintaining their complexation functionality, thus converting the pressure-induced loss risk into enhanced operational stability.
Solution Approach 2:
The patent provides beforehand cushioning by incorporating metal ions into a structurally stable porous support membrane before operation. This pre-established structural framework cushions and protects the metal cations from pressure-induced loss during feed stream contact, ensuring long-term stability while maintaining high separation selectivity.
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 new membrane achieves high olefin/paraffin selectivity and stability, with CO2 permeance of at least 200 GPU and CO2 over CH4 selectivity between 1.1 and 10, enabling efficient separation of olefins from paraffins, particularly in propylene/propane and ethylene/ethane mixtures, with improved resistance to metal cation loss under feed pressure.
Implementation Method 1
results in the formation of a reversible metal cation complex with the pi bond of olefins
Implementation Method 2
formation of a reversible metal cation complex with the pi bond of olefins
Implementation Method 3
asymmetric integrally-skinned polymeric membrane structure
Implementation Method 4
asymmetric integrally-skinned polymeric membrane structure
Implementation Method 5
incorporates these polymers into the membrane's thin, dense skin layer to fix metal cations
Data Source
AI summary
A stable high performance facilitated transport membrane comprising an asymmetric integrally-skinned polymeric membrane wherein the pores on the relatively porous, thin, dense skin layer of the membrane comprises a hydrophilic polymer such as chitosan or sodium alginate, a metal salt such as silver nitrate, or a mixture of a metal salt such as silver nitrate and hydrogen peroxide and the asymmetric integrally-skinned polymeric membrane comprises a relatively porous, thin, dense skin layer as characterized by a CO2 permeance of at least 200 GPU and a CO2 over CH4 selectivity between 1.1 and 10 at 50° C. under 50-1000 psig, 10% CO2/90% CH4 mixed gas feed pressure. The present invention further includes a method of making these membranes and their use for olefin/paraffin separations, particularly for propylene/propane and ethylene/ethane separations.