Priprava modificiranih zeolitnih imidazolatnih ogrodij s posintezno izmenjavo ligandov

Dežan, Jan (author), Golobič, Amalija (mentor), Zabukovec Logar, Nataša (comentor)

V magistrskem delu sem raziskoval učinkovito metodo funkcionalizacije kovinsko-organskih poroznih materialov (iz angl. okrajšano MOF-ov), in sicer posintezno modifikacijo zeolitnih imidazolatnih ogrodij (iz angl. okrajšano ZIF-ov) na osnovi izmenjave povezovalnih ligandov s pomočjo topil (iz angl. okrajšano SALE). Raziskave so potekale na dobro poznanem cinkovem 2-metilimidazolatu imenovanem ZIF-8. Delo je vključevalo prilagajanje literaturnih sintez ZIF-8 monokristalov ter slednjo izvedbo SALE na pripravljenih monokristalih. Za učinkovito pripravo ZIF-8 monokristalov sta se izkazali dve solvotermalni sintezi, in sicer sinteza v metanolu (okrajšano MeOH) in v N,N-dimetilformamidu (okrajšano DMF). SALE je bil nato tudi izveden v topilih MeOH in DMF zaradi preverjanja vpliva topil na stabilnost ogrodja med postopkom SALE. Za SALE je bilo uporabljenih 15 izmenjevalnih povezovalcev, in sicer: 5-iodo-2-metil-1H-imidazol, 4-bromo-1H-imidazol, 2-acetiltiazol, 2,4-dimetiltiazol, 2-metil-5-nitroimidazol, 2-nitroimidazol, 4-nitroimidazol, 4-bromo-2-metil-1H-imidazol, 1-vinil-1H-imidazol, 2-izopropil-1H-imidazol, 1H-imidazol-4-karbaldehid, metil 1H-imidazol-2-karboksilat, 4-iodo-1H-imidazol, 4-metil-1H-imidazol-5-karbaldehid in 5-metil-1H-imidazol-4-metanol. Pri karakterizaciji vzorcev je bilo uporabljenih več različnih tehnik in metod, in sicer rentgenska monokristalna difrakcija (iz angl. okrajšano SXRD) in rentgenska praškovna difrakcija (iz angl. okrajšano XRPD), termogravimetrična analiza (okrajšano TGA), vrstična elektronska mikroskopija (iz angl. okrajšano SEM), energijska disperzivna spektroskopija (okrajšano EDS), infrardeča spektroskopija (okrajšano IR) ter dušikova fizisorpcija. Nazadnje je bilo na izbranih vzorcih izvedeno še preverjanje učinkovitosti adsorpcije ogljikovega dioksida preko meritev izoterm. Kot najbolj obetavna materiala za zajem CO2 sta se izkazala vzorca ZIF8-DMF in DMF-IZOP-M+D. Prvi vzorec je ZIF-8 pripravljen v topilu DMF, na katerem SALE ni bil izveden. Drugi vzorec je tudi ZIF-8 pripravljen v topilu DMF, na katerem pa je potekal SALE z izmenjevalnim povezovalcem 2-izopropil-1H-imidazolom v mešanem topilu MeOH in DMF v razmerju 1 / 1.

• Language: Slovenian
• Keywords: kovinsko-organski porozni materiali, zeolitna imidazolatna ogrodja, ZIF-8, nanoporozni materiali, zajem ogljikovega dioksida
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: FKKT - Faculty of Chemistry and Chemical Technology
• Year: 2023
• PID: 20.500.12556/RUL-149140
• COBISS.SI-ID: 165150723
• Publication date in RUL: 04.09.2023

Secondary language

• Language: English
• Title: Preparation of modified zeolite imidazolate frameworks by post-synthesis ligand exchange

Abstract

In this thesis I researched an efficient method of functionalisation of metal-organic frameworks (shortened MOFs) – post-synthetic modification of zeolitic imidazolate frameworks (shortened ZIFs) based on solvent-assisted ligand exchange (shortened SALE). Research was made on a well known ZIF named ZIF-8. The work included adaptation of literature ZIF-8 monocrystal synthesis procedures and further SALE on prepared monocrystals. Two solvothermal methods were found as efficient preparations of ZIF-8 monocrystals, first one using methanol (shorter MeOH) and the second one using N,N-dimethylformamide (shorter DMF). SALE was then also performed using MeOH and DMF as solvents to test solvent impact on framework stability during the procedure. The 15 linkers used for SALE were the following: 5-iodo-2-methyl-1H-imidazole, 4-bromo-1H-imidazole, 2-acetylthiazole, 2,4-dimethylthiazole, 2-methyl-5-nitroimidazole, 2-nitroimidazole, 4-nitroimidazole, 4-bromo-2-methyl-1H-imidazole, 1-vinyl-1H-imidazole, 2-isopropyl-1H-imidazole, 1H-imidazole-4-carbaldehyde, methyl 1H-imidazole-2-carboxylate, 4-iodo-1H-imidazole, 4-methyl-1H-imidazole-5-carbaldehyde and 5-methyl-1H-imidazole-4-methanol. For sample characterisation multiple techniques and methods were used, those being single-crystal X-ray diffraction (shortened SXRD) and X-ray powder diffraction (shortened XRPD), thermogravimetric analysis (shortened TGA), scanning electron microscopy (shortened SEM), energy dispersive spectroscopy (shortened EDS), infrared spectroscopy (shortened IR) and nitrogen physisorption. Lastly carbon dioxide isotherms were collected for select samples to study their efficiency in adsorption of carbon dioxide. Samples ZIF8-DMF and DMF-IZOP-M+D proved to be the two materials best suited for CO2 capture. The first is ZIF-8, which was prepared in the solvent DMF and on which SALE was not performed. The second is ZIF-8, which was also prepared in the solvent DMF, but on which SALE was performed with the exchange linker 2-isopropyl-1H-imidazole in a mixed solvent of MeOH and DMF in a ratio of 1 / 1.

• Keywords: metal-organic frameworks, zeolitic imidazolate frameworks, ZIF-8, nanoporous materials, carbon dioxide capture