Composite Amine Absorbent for Selective H2S Removal
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Solution Overview
Problem
Conventional acid gas deacidification processes face limitations in selectivity and kinetics, particularly in the separation of H2S from CO2, leading to inefficient gas treatment and high operational costs due to slow reaction rates and limited cyclic capacity of absorbent solutions.
Innovation Solution
An absorbent solution comprising a mixture of 1,2-bis-(2-dimethylaminoethoxy)-ethane and 2-[2-(2-dimethylaminoethoxy)-ethoxy]-ethanol, along with additional amines, is used to enhance the cyclic absorption capacity and selectivity for H2S relative to CO2, improving the efficiency of acid gas treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional amine solutions are used for acid gas deacidification, then the process can remove acidic compounds from gas, but the selectivity of H2S absorption relative to CO2 is insufficient
Solution Approach 1:
The patent uses a composite amine system comprising a hindered secondary amine (cyclic or acyclic) combined with a tertiary amine, creating a synergistic effect where the hindered secondary amine provides high H2S selectivity through instantaneous reaction kinetics, while the tertiary amine contributes to overall absorption capacity. This composite approach resolves the contradiction by combining the strengths of different amine types.
Solution Approach 2:
The patent modifies the chemical structure parameters of the amine molecules, specifically using hindered secondary amines with severe steric hindrance (two secondary carbons in alpha of nitrogen or one tertiary carbon in alpha of nitrogen) to alter reaction kinetics. This structural parameter change enables instantaneous H2S capture while maintaining manageable CO2 reaction rates, achieving the desired selectivity-c capacity balance.
2Manufacturing precision
If tertiary amines or hindered secondary amines are used to achieve selective H2S removal, then selectivity improves, but reaction kinetics with CO2 become too slow
Solution Approach 1:
The patent creates a dynamic amine system where different amine components react at different rates with different acid gases. The hindered secondary amine provides instantaneous H2S reaction, while the tertiary amine component modulates the overall system kinetics. This dynamic behavior allows the system to adapt its reaction rate profile to achieve both selectivity and acceptable overall reaction speed.
Solution Approach 2:
The patent applies local quality by assigning different functional roles to different amine components within the same solution. The hindered secondary amine is specifically structured to provide instantaneous H2S capture at its molecular level, while the tertiary amine component provides broader acid gas absorption capacity. This localized functional differentiation resolves the kinetics-selectivity contradiction.
3Productivity
If amine solutions with fast CO2 capture kinetics are used, then CO2 absorption capacity increases, but H2S selectivity decreases
Solution Approach 1:
The patent applies partial action by using a mixture where the hindered secondary amine component specifically targets H2S with instantaneous kinetics, while the tertiary amine component provides additional CO2 absorption capacity. The hindered secondary amine is present in sufficient quantity to ensure H2S selectivity, while the tertiary amine is added in amounts that enhance overall capacity without compromising the selective H2S reaction pathway.
4Productivity
If the flow rate of absorbent solution is increased to improve gas treatment efficiency, then productivity increases, but operational costs increase
Solution Approach 1:
The patent changes the chemical parameters of the absorbent solution by using hindered secondary amines with instantaneous H2S reaction kinetics. This parameter change allows the system to achieve high gas treatment efficiency at lower absorbent flow rates, because each unit of absorbent solution is much more effective at capturing H2S. The reduced flow rate directly translates to lower pumping energy costs and reduced operational expenses.
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 solution achieves higher absorption capacities and selectivity for H2S over CO2, reducing the flow rate of the absorbent solution and lowering operational costs by increasing the cyclic capacity and reaction kinetics, thus optimizing gas treatment processes.
Implementation Method 1
The gas is deacidified by bringing it into contact with the absorbent solution... A chemical solvent corresponds to an aqueous solution comprising a reagent which reacts selectively with the acidic compounds (H2S, CO2, COS, CS2, etc.) present in the treated gas to form salts
Implementation Method 2
The chemical reactions are reversible, which allows the solvent loaded with acidic compounds to then be deacidified, for example under the action of heat, to release on the one hand the acidic compounds in the form of gas
Data Source
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AI summary
The invention relates to an absorbent solution for absorbing acid compounds, such as hydrogen sulphide and carbon dioxide, from a gas effluent, comprising water and a mixture of amines comprising 1,2-bis-(2-dimethylaminoethoxy)-ethane and 2-[2-(2- dimethylaminoethoxy)-ethoxy]-ethanol of respective formulae (I) and (II) below, and to a method for eliminating acid compounds contained in a gas effluent by means of said solution.