Dispersing LiCl in Zwitterionic COF for Highly Efficient Ammonia Storage and Separation
Yu Fu1, Yue Wu1, Jiahui Zeng1
1School of Chemical Engineering and Technology, Xi'an Jiaotong University, Xi'an, 710049, China.
Chemistry (Weinheim an Der Bergstrasse, Germany)
|August 29, 2023
Summary
This study introduces zwitterionic covalent organic frameworks (COFs) for superior ammonia (NH3) storage and separation. The novel material achieves record-breaking adsorption capacity, enabling efficient and reversible ammonia capture.
Area of Science:
- Materials Science
- Chemical Engineering
- Adsorption Science
Background:
- Efficient ammonia (NH3) storage and separation are critical for the chemical industry.
- Existing porous materials often face limitations in capacity and safety for NH3 handling.
- Developing advanced adsorbents is essential for sustainable ammonia-based technologies.
Purpose of the Study:
- To develop a novel zwitterionic covalent organic framework (COF) composite for enhanced ammonia storage and separation.
- To achieve a record adsorption capacity for ammonia capture.
- To investigate the mechanism of ammonia adsorption and separation in the zwitterionic COF-LiCl system.
Main Methods:
- Synthesis of zwitterionic COF as a porous host.
- Impregnation of lithium chloride (LiCl) into the zwitterionic COF channels.
- Ammonia adsorption/desorption experiments at specified conditions (25°C, 1 bar).
- Breakthrough experiments for NH3 separation from gas mixtures (NH3/CO2/N2).
- Density Functional Theory (DFT) calculations, X-ray Photoelectron Spectroscopy (XPS), and 7Li Nuclear Magnetic Resonance (NMR) for mechanistic insights.
Main Results:
- The zwitterionic COF-LiCl composite demonstrated a record ammonia adsorption capacity of 44.98 mmol/g at 25°C and 1 bar.
- The adsorption process was found to be completely reversible.
- Efficient separation of ammonia from a mixture of NH3, CO2, and N2 was successfully achieved via breakthrough experiments.
- DFT, XPS, and NMR studies provided insights into the interaction between the zwitterionic COF and LiCl, elucidating the adsorption mechanism.
Conclusions:
- Zwitterionic COFs serve as effective porous hosts for dispersing LiCl, leading to superior ammonia storage and separation performance.
- The developed composite offers a promising solution for high-capacity, reversible ammonia capture.
- This research opens new avenues for designing advanced adsorbents for industrial ammonia applications.
Keywords:
NH3 storage and separationcovalent organic frameworksdispersion of metal halidezwitterionic materialMore Related Videos
Related Concept Videos
01:07Acid Halides to Amides: Aminolysis
2.9K
Aminolysis is a nucleophilic acyl substitution reaction, where ammonia or amines act as nucleophiles to give the substitution product. Acid halides react with ammonia, primary amines, and secondary amines to yield primary, secondary, and tertiary amides, respectively.
In the first step of the aminolysis mechanism, the amine attacks the carbonyl carbon of the acyl chloride to form a tetrahedral intermediate. In the second step, the carbonyl group is re-formed with the elimination of a chloride...
In the first step of the aminolysis mechanism, the amine attacks the carbonyl carbon of the acyl chloride to form a tetrahedral intermediate. In the second step, the carbonyl group is re-formed with the elimination of a chloride...
2.9K
00:56Extraction: Advanced Methods
482
Metal ions can be separated from one another by complexation with organic ligands–the chelating agent– to form uncharged chelates. Here, the chelating agent must contain hydrophobic groups and behave as a weak acid, losing a proton to bind with the metal. Since most organic ligands used in this process are insoluble or undergo oxidation in the aqueous phase, the chelating agent is initially added to the organic phase and extracted into the aqueous phase. The metal-ligand complex is...
482
01:30Preparation of Amines: Alkylation of Ammonia and Amines
3.4K
Alkylation is one of the methods used to prepare amines. Direct alkylation of ammonia or a primary amine with an alkyl halide gives polyalkylated amines along with a quaternary ammonium salt through successive SN2 reactions. This process of making the quaternary salt through the direct alkylation method is called exhaustive alkylation.
Each alkylation step makes the nitrogen center more nucleophilic, which triggers successive alkylations until a quaternary ammonium salt is formed. Considering...
Each alkylation step makes the nitrogen center more nucleophilic, which triggers successive alkylations until a quaternary ammonium salt is formed. Considering...
3.4K
01:17Ion Exchange
621
Ion exchange chromatography separates charged molecules from a solution by reversibly exchanging them with mobile, or 'active', ions associated with the oppositely charged stationary phase. This method can be used to separate ions, soften and deionize water, and purify solutions. The polymers comprising the ion-exchange column are high-molecular-weight and chemically stable polymers, crosslinked to be porous and essentially insoluble. They are also functionalized with either acidic or...
621
01:25Basicity of Heterocyclic Aromatic Amines
6.1K
Heterocyclic amines, where the N atom is a part of an alicyclic system, are similar in basicity to alkylamines. Interestingly, the heterocyclic amine having a nitrogen atom as part of an aromatic ring has much less basicity than its corresponding alicyclic counterpart. For this reason, as presented in Figure 1, piperidine (pKb = 2.8) is significantly more basic than pyridine (pKb = 8.8).
6.1K
01:19Structure of Amines
2.6K
The hybridized nitrogen atom in amines possesses a lone pair of electrons and is bound to three substituents with a bond angle of around 108°, which is less than the tetrahedral angle of 109.5°. However, the C–N–H bond angle is slightly larger at 112°, with a carbon–nitrogen bond length of 147 pm. This carbon–nitrogen bond length of of amines is longer than the carbon–oxygen bond of alcohols (143 pm) but shorter than alkanes’...
2.6K