Hydroxyl-Free Amine Absorbent for Selective H2S Removal
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current processes for removing acid gases, particularly hydrogen sulfide (H2S) from gas mixtures containing carbon dioxide (CO2), face challenges such as reduced selectivity at higher pressures, foaming issues due to hydroxyl groups in alkanolamines, and volatility leading to absorbent losses, which affect the efficiency and cost of regeneration and recompression in natural gas systems.
Innovation Solution
The use of an absorbent comprising a compound of the general formula (I) with a secondary amino group and a hydroxyl group vicinal to a hydroxy or alkoxy group, which reduces hydroxyl reactivity towards CO2, combined with a diluent and an activator, to enhance selectivity and cyclic capacity while minimizing volatility and foaming, allowing for effective H2S removal from gas streams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If alkanolamines with hydroxyl groups are used as absorbent, then solubility of absorbent/acid gas reaction products is improved, but foaming phenomena occur during operation
Solution Approach 1:
The patent extracts the problematic hydroxyl groups from the amine structure to eliminate foaming while retaining the beneficial amine functionality for acid gas absorption. The absorbent used is a hydroxyl-free amine compound, specifically removing the hydroxyl substituent that causes foaming while maintaining the amine's ability to react with acid gases.
Solution Approach 2:
The patent changes the chemical structure parameter of the absorbent by using hydroxyl-free amine compounds instead of traditional alkanolamines. This structural parameter change eliminates the surfactant properties that cause foaming while maintaining adequate solubility and absorption performance through alternative molecular design.
2Productivity
If alkanolamines are used for acid gas removal at high pressures, then acid gas removal effectiveness is improved, but H2S selectivity decreases markedly
Solution Approach 1:
The patent changes the chemical composition parameter by using hydroxyl-free amine compounds that lack the hydroxyl groups present in conventional alkanolamines. This parameter change maintains high pressure effectiveness while preserving H2S selectivity because the absence of hydroxyl groups prevents the unwanted reactions that occur at high pressures with traditional alkanolamines.
Solution Approach 2:
The patent employs a simplified amine structure without hydroxyl groups that provides sufficient functionality for a limited time during the absorption process, avoiding the need for complex molecular structures that would maintain selectivity at high pressures. The straightforward amine structure performs its function effectively and then is regenerated.
3Productivity
If conventional absorbents are used for CO2 removal, then CO2 removal is achieved, but H2S is also removed reducing the ability to enrich H2S for downstream processing
Solution Approach 1:
The patent applies local quality by designing an absorbent with specific chemical properties (hydroxyl-free amine structure) that creates different reactivity characteristics for CO2 and H2S. The absorbent structure provides preferential reactivity with H2S while maintaining adequate CO2 removal capability, allowing spatial and chemical differentiation in gas removal 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 proposed absorbent process achieves high selectivity for H2S removal with improved cyclic capacity and reduced volatility, leading to efficient acid gas treatment with lower operational costs and reduced environmental impact.
Implementation Method 1
When acid gases are dissolved in the absorbent, ions form with the bases. The absorbent can be regenerated by decompression to a lower pressure and/or by stripping, whereby the ionic species react in reverse and the acid gases are released and/or stripped out by means of steam.
Implementation Method 2
H2S reacts more rapidly with the amine groups of the sorbent to form a hydrosulfide salt in aqueous solution
Implementation Method 3
CO2 is reacted in a slow reaction with the amine and with water to give bicarbonate
Implementation Method 4
The absorbent can be regenerated by decompression to a lower pressure and/or by stripping, whereby the ionic species react in reverse and the acid gases are released
Implementation Method 5
The absorbent can be regenerated by decompression to a lower pressure and/or by stripping, whereby the ionic species react in reverse and the acid gases are released and/or stripped out by means of steam
Data Source
AI summary
In a process for removal of acid gases from a fluid stream the fluid stream is contacted with an absorbent to obtain a treated fluid stream and a laden absorbent. The absorbent comprises a diluent and a compound of the general formula (I) wherein R1 is C1-C3-alkyl; R2 is C1-C3-alkyl; R3 is selected from hydrogen and C1-C3-alkyl; and R4 is selected from hydrogen and C1-C3-alkyl.