Ionic Liquid Membrane for Olefin Separation Stability
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Solution Overview
Problem
Current methods for separating olefins from paraffins in petroleum refining, such as distillation and facilitated-transport membranes, face challenges with stability, diffusion rates, and selectivity, particularly due to low relative volatilities and instability issues.
Innovation Solution
Development of an ionic liquid comprising a silver (I) ion complex with neutral ligands and a specific anionic portion, which forms a membrane for olefin-paraffin separation, offering improved stability, diffusion rates, and selectivity by using a larger or asymmetrical anion, increasing silver ion content, and enhancing permeability and hydrophobicity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If facilitated-transport membranes with silver ion are used for olefin separation, then selectivity and diffusion rates are improved, but stability deteriorates due to solvent vaporization and air oxidation
Solution Approach 1:
The patent uses a polymer support matrix as an intermediary carrier that hosts the silver ion complex and liquid membrane material. This polymer support provides structural stability and prevents direct exposure to environmental factors (oxygen, moisture) that would cause degradation, while still allowing the silver ion to facilitate olefin transport through the membrane.
Solution Approach 2:
The invention creates a composite membrane structure combining polymer support material with silver ion-containing liquid membrane material. This composite structure integrates the stability of the polymer matrix with the high diffusion rates and selectivity of the silver ion complex, achieving both reliability and productivity simultaneously.
2Reliability
If solid polymer membranes are used for olefin separation, then stability is improved, but diffusion rates deteriorate
Solution Approach 1:
The patent applies local quality by creating a specialized layer within the polymer membrane that contains the silver ion complex. This local region has different properties (higher diffusion rate, olefin selectivity) compared to the bulk polymer matrix, allowing fast transport while the overall membrane structure maintains stability.
Solution Approach 2:
The silver ion complex acts as an intermediary that facilitates rapid olefin transport through the polymer matrix. The silver ion binds selectively to olefins and enables their rapid diffusion through the membrane, bridging the gap between stability and high diffusion rates.
3Productivity
If conventional liquid-supported membranes are used, then diffusion rates are maintained, but silver ion content is insufficient to maximize transport flux
Solution Approach 1:
The patent changes the chemical parameters of the liquid membrane composition by incorporating specific ligands (amides, amines, olefins, or organonitriles) that form stable complexes with silver ions. This parameter change allows the membrane to maintain high silver ion content while preserving liquid-like diffusion rates and olefin 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 ionic liquid membrane achieves enhanced stability and selectivity in olefin-paraffin separation, increasing transport flux and reducing energy and capital costs by maintaining high diffusion rates and selectivity while being more stable than conventional membranes.
Implementation Method 1
the ILM typically contains an olefin-transporting metal ion (e.g., Ag+) dissolved in a solvent. Such ILMs are generally selective toward olefins and have fast diffusion rates
Implementation Method 2
They are known to suffer from a significant degree of instability due to solvent vaporization and air oxidation. Solid polymer membranes are also known for this purpose. They generally possess improved stabilities. However, a significant drawback of solid polymer membranes is their slow diffusion
Data Source
AI summary
The invention is directed to an ionic liquid comprising (i) a cationic portion containing a complex of a silver (I) ion and one or more neutral ligands selected from organoamides, organoamines, olefins, and organonitriles, and (ii) an anionic portion having the chemical formulawherein m and n are independently 0 or an integer of 1 or above, and p is 0 or 1, provided that when p is 0, the group —N—SO2—(CF2)nCF3 subtended by p is replaced with an oxide atom connected to the shown sulfur atom. The invention is also directed to a method for separating an olefin from an olefin-paraffin mixture by passing the mixture through a layer of the ionic liquid described above.