| Title: | Green synthesis of Zeolitic Imidazolate Frameworks and their evaluation for ▫$CO_2$▫ capture in humid conditions : dissertation |
|---|
| Authors: | ID Škrjanc, Aljaž (Author)
ID Zabukovec Logar, Nataša (Mentor) More about this mentor...  |
|---|
| Files: |  Aljaz_Skrjanc.pdf (15,56 MB)
MD5: 4C23D76861D79F8B3FF095E0030C3F14
|
|---|
| Language: | English |
|---|
| Work type: | Doctoral dissertation |
|---|
| Typology: | 2.08 - Doctoral Dissertation |
|---|
| Organization: | FPŠ - Graduate School
|
|---|
| Abstract: | Emissions of green-house gasses have been in the forefront of scientific research in recent decades. One of the approaches towards reducing the amount of green gas CO2 in the atmosphere is its capture and storage with subsequent conversion where pure enough CO2 can be regenerated. While CO2 capture widely utilizes two mature technologies, amine absorption and cryogenic distillation, they both have significant downsides, in either cost or potential new danger to the environment. To that end an adsorption-based CO2 capture has seen quite a lot of interest in recently. Nanoporous materials have been extensively studied for this application, starting with zeolites, followed by aluminophosphates and also the new members of the porous materials group, the so called reticular porous materials. Metal-Organic Frameworks (MOFs), the first discovered reticular porous materials have shown very promising results for post combustion CO2 capture and recently also for in-door and direct air capture. MOFs are in general enough thermally stable for CO2 capture, their main weakness for wide applicability is sometimes lower selectivity for CO2 in real gas mixtures and lower stability in humid conditions.
Zeolitic imidazolate frameworks (ZIFs), a subgroup of MOFs, have in recent years been extensively studied for sorption applications, also CO2, due to their superior stability and kinetics for vapour/gas adsorption if compared to carboxylate-based MOFs. While extensively studied, an overview of articles shows that most research is limited to a limited set group of frameworks, with ZIF-8 being used in more than half of ZIF papers. While ZIF-8 has successfully been prepared in water and even in solvent-free conditions, the rest of the ZIFs synthesis still heavily rely on solvothermal synthesis with formamide based solvent systems and synthesis times upwards of 5 days. Even in the case of ZIF-8, while greener synthesis approaches are available, dimethylformamide (DMF) synthesis still prevails in the cases tested for CO2 capture, mainly due to the increased CO2 uptake resulting from the synergistic contribution of the remaining DMF solvent in the pores.
The goal of this thesis was to develop green synthesis approaches, both solvothermal and mechanochemical, for known ZIFs and then to extend the scope towards preparation of new ZIF materials. The goal for latter was to experimentally determine the optimal topology and functionality of ZIFs for CO2 adsorption in humid conditions. Model humid gas isotherms were developed and measured for a series of ZIFs with mostly SOD (sodalite) and RHO framework topologies and Zn and Ni as metal nodes. Finally, some novel bio-based binder materials were tested for the use with ZIFs.
The sorption tests revealed than the SOD topology ZIFs have high potential for CO2 sorption applications, as the adsorption is rapid and further combination of terminally functionalised imidazoles in those frameworks drastically increases the frameworks affinity for CO2 at lower pressures. With most common 4,5- functionalised imidazole having hydrophilic functional groups, the challenge of competitive water sorption still remains. On the other hand some hydrophobic 4,5-substituted sodalite ZIFs, both with 4,5-dichloroimidazole, show excellent CO2 sorption and even complete hydrophobicity. The results led us to hypothesize that further research on ZIFs- for CO2 capture has to shift form 2 substituted sodalite frameworks to 4,5 substituted frameworks with strongly dipolar hydrophobic groups. The hydrophilic polar groups currently in use lead to issues with competitive water adsorption, due to their potential to form hydrogen bonds with water. Furthermore, some new agar and alginate based shaping methods were tested, as both potential binders are not environmentally toxic and are already used on the industrial scale world-wide for other applications. |
|---|
| Keywords: | carbon capture, synthesis, metal-organic frameworks, zeolitic imidazolate frameworks, nanoporous materials, dissertations |
|---|
| Publication status: | Published |
|---|
| Publication version: | Version of Record |
|---|
| Place of publishing: | Nova Gorica |
|---|
| Place of performance: | Nova Gorica |
|---|
| Publisher: | A. Škrjanc |
|---|
| Year of publishing: | 2024 |
|---|
| Year of performance: | 2024 |
|---|
| Number of pages: | 108 str., CXLIII str. pril. |
|---|
| PID: | 20.500.12556/RUNG-9285 |
|---|
| COBISS.SI-ID: | 206909187 |
|---|
| UDC: | 620.1/.2 |
|---|
| NUK URN: | URN:SI:UNG:REP:GHGD7TOM |
|---|
| Publication date in RUNG: | 10.09.2024 |
|---|
| Views: | 793 |
|---|
| Downloads: | 21 |
|---|
| Metadata: |    |
|---|
|
:
|
Copy citation |
|---|
| | | | Average score: | (0 votes) |
|---|
| Your score: | Voting is allowed only for logged in users. |
|---|
| Share: |  |
|---|
Hover the mouse pointer over a document title to show the abstract or click
on the title to get all document metadata. |
