Ionic Liquid-Physical Solvent Mixtures for CO2 Absorption
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Solution Overview
Problem
Current carbon dioxide removal technologies, such as physical absorption solvents, face challenges including low operating temperatures, high pressures, and the need for refrigeration and effluent washing, which increase costs and complexity, while also being limited by viscosity issues that reduce mass transfer rates and tray efficiencies.
Innovation Solution
Combining phosphonium acetate ionic liquids with physical absorption solvents like dimethyl ethers of polyethylene glycol and methanol to create a composition that absorbs CO2 from gas mixtures, eliminating the need for refrigeration and effluent washing, and improving solvent performance by adjusting the volume percentage of ionic liquids within the mixture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If physical absorption solvents are used for CO2 removal, then CO2 absorption capacity is improved, but operating temperature must be lowered and operating pressure must be increased
Solution Approach 1:
The patent changes the chemical composition parameters of the absorption medium by introducing ionic liquids with specific functional groups (carboxylate, carbonate, carbamate) that have high CO2 affinity. This allows the system to achieve high CO2 absorption capacity at ambient temperature and pressure conditions, eliminating the need for extreme operating conditions required by conventional physical absorption solvents
Solution Approach 2:
The patent creates a composite absorption system combining ionic liquids with conventional physical absorption solvents. The ionic liquid component provides high CO2 selectivity and capacity through chemical interaction, while the physical absorption solvent enhances bulk absorption capacity. This composite approach allows operation under milder conditions while maintaining high CO2 removal efficiency
2Quantity of substance
If physical absorption solvents are used for CO2 removal, then CO2 absorption capacity is improved, but operating pressure must be increased
Solution Approach 1:
The patent changes the thermodynamic parameters of the absorption process by using ionic liquids that facilitate CO2 absorption at lower pressures. The ionic liquid's chemical structure (with carboxylate, carbonate, or carbamate groups) enables CO2 to be absorbed at near-ambient pressures, eliminating the high pressure requirements of conventional physical absorption systems
Solution Approach 2:
The patent replaces the mechanically intensive high-pressure absorption process with a chemically driven absorption mechanism. Instead of relying on high pressure to force CO2 into the solvent (physical absorption), the system uses chemical interactions between CO2 and ionic liquid functional groups, significantly reducing the pressure requirement
3Quantity of substance
If ionic liquids are used to improve CO2 absorption capacity, then CO2 removal efficiency is improved, but viscosity increases reducing mass transfer rates
Solution Approach 1:
The patent optimizes the concentration parameter of ionic liquid in the absorption medium, using it as an additive at controlled levels rather than as the sole absorption medium. This concentration optimization balances the high CO2 capacity of ionic liquids with acceptable viscosity and mass transfer characteristics of the overall system
Solution Approach 2:
The patent creates a composite system where ionic liquid is combined with conventional physical absorption solvents. The physical absorption solvent component provides lower viscosity and better mass transfer properties, while the ionic liquid component contributes high CO2 capacity. This composite approach balances capacity and productivity
4Quantity of substance
If conventional physical absorption solvents are used, then CO2 removal is achieved, but refrigeration and effluent washing are required increasing complexity
Solution Approach 1:
The ionic liquid-based system is self-sufficient in that it does not require external refrigeration systems or effluent washing facilities. The ionic liquid's chemical properties enable CO2 absorption at ambient conditions, and the solvent can be regenerated through simple heating or pressure reduction, eliminating complex auxiliary systems
Solution Approach 2:
The patent changes the operating parameter range to ambient temperature and pressure conditions, which eliminates the need for refrigeration equipment. Additionally, the ionic liquid's thermal stability and low volatility eliminate the need for effluent washing systems, simplifying the overall process configuration
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 combination enhances the capacity and reduces operating pressures of the solvent system, achieving better CO2 removal efficiency without the need for refrigeration or effluent washing, thus improving the overall performance and reducing costs.
Implementation Method 1
Mixtures of physical absorption solvents and ionic liquids for gas separation - The invention involves a composition comprising an ionic liquid and a physical absorption solvent
Implementation Method 2
WO 201217183, a process was disclosed for separating carbon dioxide from a gaseous stream through chemisorption by 1-ethyl-3-methylimidazolium (emim) or 1-propyl-3-methylimidazolium (pmim) containing ionic liquids
Data Source
Figure 1
AI summary
The invention comprises an absorbent composition and process for purification of gaseous mixtures. The composition comprises a mixture of a physical absorption solvent and an ionic liquid. It was found that the mixtures provided improved absorption of a gas component, such as carbon dioxide, when compared physical absorption solvents.