Ionic Liquid Solvent Gas Separation

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Solution Overview

Problem

Current separation techniques for process streams, such as distillation and ionic liquid membranes, face challenges with high costs, inefficiencies, and limitations in capturing gaseous components with close boiling points or requiring significant capital expenditure, especially when dealing with fluid components like olefins and paraffins, acid gases, and other gases in industrial processes.

Innovation Solution

A method and system utilizing an ionic liquid solvent to capture and recover gaseous components from process streams, including olefins, alkane, acid gases, and other gases, through absorption, dissolution, or complexation, with a regenerator to regenerate the solvent and release the captured gases, potentially using a membrane unit for additional separation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional distillation is used to separate fluid components, then separation can be achieved, but the process becomes cost-prohibitive due to large number of stages and high reflux ratios required when components have close boiling points

Engineering Contradiction:
Improveseparation precisionVSAvoidnumber of distillation stages
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent changes the physical-chemical parameters of the separation system by using ionic liquid solvents with specific properties (negligible vapor pressure, tunable selectivity) instead of conventional distillation parameters (reflux ratios, number of stages). This allows separation of components with close boiling points through selective absorption rather than repeated vaporization-condensation cycles.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The ionic liquid solvent acts as an intermediary substance that selectively interacts with target gaseous components through absorption or complexation. This mediator enables separation without requiring the components to undergo phase changes multiple times, thereby reducing the number of stages needed.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Manufacturing precision

If ionic liquid membranes are used for absorption, then separation can be achieved, but the process suffers from poor flux or requires significant capital expenditure for commercial applications due to membrane diffusion rate limitations

Engineering Contradiction:
Improveseparation selectivityVSAvoidflux rate
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The patent transitions from membrane-based separation (relying on diffusion through solid/liquid barriers) to liquid-phase absorption (relying on bulk fluid dynamics and mass transfer). This allows higher throughput by utilizing the bulk flow characteristics of ionic liquids rather than being constrained by membrane diffusion rates.

Inventive Principle:
Principle #29Pneumatics and hydraulics

Solution Approach 2:

The patent changes the transport mechanism from diffusion-limited (membranes) to convection-enhanced mass transfer (liquid absorption). By using ionic liquids in a liquid-phase absorption process, the system achieves higher flux rates while maintaining selectivity through the solvent's chemical properties rather than physical barrier constraints.

Inventive Principle:
Principle #35Parameter changes

3Manufacturing precision

If aqueous solutions of metal salts are used for absorption, then separation can be achieved, but water vapor pressure causes inefficient recovery requiring de-watering steps

Engineering Contradiction:
Improveseparation capabilityVSAvoidwater carryover
Core Design Contradiction:
Manufacturing precisionVSLoss of substance

Solution Approach 1:

The patent replaces the conventional aqueous absorbent (water-based) with an ionic liquid absorbent that has negligible vapor pressure. This substitution eliminates the problem of water vapor carryover into the recovered gas stream, removing the need for additional de-watering equipment and steps.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent fundamentally changes the solvent parameter from water-based (high vapor pressure) to ionic liquid-based (negligible vapor pressure). This parameter change eliminates vapor phase interference during recovery, allowing direct separation without contamination and eliminating the need for de-watering operations.

Inventive Principle:
Principle #35Parameter changes

4Productivity

If ionic liquid solvents are used for capturing gaseous components, then separation efficiency is improved, but the process requires additional equipment for solvent regeneration

Engineering Contradiction:
Improveseparation efficiencyVSAvoidregeneration system
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent implements a solvent regeneration system that recovers and reuses the ionic liquid absorbent after it has captured gaseous components. The regenerator unit heats or depressurizes the loaded solvent to release the captured gas, then condenses and recycles the ionic liquid back to the absorber, creating a closed-loop system that improves efficiency while managing the added complexity through resource recovery.

Inventive Principle:
Principle #34Discarding and recovering

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 enhances process efficiency by selectively capturing and recovering valuable gaseous components, reducing the need for costly recycling or flaring, and improving the purity and recovery rates of gases like ethylene and isobutane, while minimizing solvent loss and VOC emissions.

Implementation Method 1

capturing at least a portion of the gaseous component from the process stream by an ionic liquid solvent

Methodology Applied
Scientific EffectAbsorption: Absorption (physical)

Implementation Method 2

capturing at least a portion of the gaseous component from the process stream by an ionic liquid solvent

Methodology Applied
Scientific EffectDissolution: Solvation

Implementation Method 3

capturing at least a portion of the gaseous component from the process stream by an ionic liquid solvent

Methodology Applied
Scientific EffectComplexation: Chemical Bonding

Implementation Method 4

recovering at least a portion of a captured gaseous component from the ionic liquid solvent

Methodology Applied
Scientific EffectDesorption: Desorption

Implementation Method 5

a regenerator to receive the captured stream, wherein the regenerator regenerates the ionic liquid solvent and emits the recovered gaseous component

Methodology Applied
Scientific EffectHeating: Heating

Data Source

PatentEP3244987B1Separations with ionic liquid solvents
Publication Date: 2022.06.22 CHEVRON PHILLIPS CHEMICAL COMPANY LP
  • EP3244987B1 patent drawingFigure 1
  • EP3244987B1 patent drawingFigure 2
  • EP3244987B1 patent drawingFigure 3

AI summary

Disclosed are systems and methods which provide a process stream comprising a gaseous component, capture the gaseous component from the process stream by an ionic liquid solvent of a separator, and recover a captured gaseous component from the ionic liquid solvent in a regenerator. A second gaseous component from the process stream may be captured by the ionic liquid solvent of the separator, and the second gaseous component may be recovered from the ionic liquid solvent in the regenerator. Alternatively, the second gaseous component from the process stream may be uncaptured by the ionic liquid solvent, and the uncaptured second gaseous component may be recovered from a membrane unit.