Cyclic Amine Absorption Medium for Low-Energy CO2 Capture
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Solution Overview
Problem
Existing methods for removing carbon dioxide from flue gases face challenges such as high energy requirements for regeneration, slow reaction kinetics, and instability in the presence of oxygen, which are not adequately addressed by current absorption media like monoethanolamine and other alkanolamines.
Innovation Solution
An absorption medium comprising an aqueous solution of cyclic amine compounds with tertiary and sterically hindered secondary amine groups, specifically 1-hydroxyethylpiperidine and piperazine, which provides improved capacity, absorption rate, stability, and low energy requirements for regeneration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If monoethanolamine is used as absorption medium, then high reactivity between amine and carbon dioxide is achieved, but high absorption enthalpy and high energy requirement for regeneration occur
Solution Approach 1:
The patent combines two different amine compounds (monoethanolamine and diethanolamine or methyldiethanolamine) in specific ratios (1:4 to 4:1) to create a composite absorption medium that balances high reactivity with lower regeneration energy requirements, leveraging the complementary properties of each component
Solution Approach 2:
The patent modifies the chemical composition parameters of the absorption medium by using substituted amine compounds with specific structural features (cyclic structures, hydroxyl groups, amino groups) to alter the absorption enthalpy and reaction kinetics, achieving optimal performance for flue gas conditions
2Use of energy by moving object
If alkanolamines with lower energy requirement for regeneration are used, then energy efficiency improves, but reaction kinetics between carbon dioxide and amine become slower
Solution Approach 1:
The patent creates a composite system combining fast-reacting but high-energy amine compounds with slow-reacting but low-energy amine compounds, where the fast-reacting component ensures high absorption kinetics while the slow-reacting component provides low regeneration energy requirements, achieving both goals simultaneously
3Quantity of substance
If absorption medium capacity is increased for low CO2 partial pressures, then separation efficiency improves, but oxygen stability and susceptibility to degradation worsen
Solution Approach 1:
The patent changes the chemical structure parameters of the amine compounds by introducing cyclic structures (piperidine, piperazine rings) and specific substituents (hydroxyl groups at specific positions) that enhance both CO2 absorption capacity at low partial pressures and resistance to oxidative degradation in the presence of oxygen
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 proposed absorption medium achieves higher carbon dioxide absorption rates with lower energy requirements for regeneration and enhanced stability, particularly suitable for treating oxygen-comprising flue gases, thereby improving the efficiency and cost-effectiveness of carbon dioxide capture.
Implementation Method 1
use is frequently made of aqueous solutions of organic bases, e.g. alkanolamines, as absorption media for removing acid gases, such as carbon dioxide, from fluid streams
Implementation Method 2
When acid gases are dissolved, ionic products are formed from the base and the acid gas components
Implementation Method 3
The absorption medium can be regenerated by heating, expansion to a lower pressure or by stripping, wherein the ionic products react back to form acid gases
Implementation Method 4
the acid gases are stripped off by means of steam
Data Source
AI summary
An absorption medium for removing acid gases from a fluid stream comprises an aqueous solution of A) at least one cyclic amine compound having solely tertiary amine groups and/or sterically hindered secondary amine groups and B) at least one cyclic amine compound having at least one sterically unhindered secondary amine group. The absorption medium comprises, e.g., an aqueous solution of A) 1-hydroxyethylpiperidine and/or triethylenediamine and B) piperazine. The absorption medium is particularly suitable for separating off carbon dioxide from flue gases and satisfies the following criteria: (i) sufficient capacity at low CO2 partial pressures; (ii) sufficiently rapid absorption rate at low CO2 partial pressures; (iii) stability toward oxygen; (iv) low vapor pressure for reducing solvent losses; and (v) low energy requirement for regeneration of the absorption medium.