doktorska disertacija
Maja Reberc (Author), Anton Meden (Mentor), Franc Perdih (Thesis defence commission member), Matjaž Mazaj (Thesis defence commission member), Anton Kokalj (Thesis defence commission member), Jernej Stare (Co-mentor)

Abstract

Uporaba vodika kot nosilca energije je eno večjih področij znanstvenih raziskav, osredotočenih na zmanjšanje ogljičnega odtisa energetike. Med glavnimi težavami področja so materiali in sistemi za hranjenje vodika, saj ima ta kljub veliki masni energijski gostoti nizko volumsko gostoto. Z namenom shranjevanja vodika sem v tem delu razvila kovinsko-organski material na osnovi derivata imidazola in borohidridnih enot. V prvem delu je predstavljena sinteza in karakterizacija materiala ZIF-8/LiBH$_4$, sestavljenega iz mikroporoznega zeolitnega imidazolatnega ogrodja ZIF-8 (spojine cinkovih kationov v vlogi kovinskih centrov ter 2-metilimidazolatnih anionov v vlogi ligandov) in v njem nanoomejenega gostujočega borohidrida LiBH$_4$. Pokazali smo, da material prične sproščati vodik pri relativno nizki temperaturi okrog 120 ◦C, veže CO$_2$ in ni stabilen na zraku. Na podlagi rezultatov računskih metod, osnovanih na periodični metodologiji DFT, smo sklepali tudi na možnosti urejanja gostujoče zvrsti v porah ogrodja. Dodatno smo karakterizirali tudi [Mg$_3${(Im)BH$_2$(Im)}$_6$(ImH)$_6$]·CH$_3$CN (v formuli Im$^–$ predstavlja imidazolatni anion, ImH pa 1H-imidazol), kompleksno spojino, sestavljeno iz treh magnezijevih kationov, povezanih z mostički iz imidazola in borohidridnega aniona, ter jo poskusili uporabiti kot prekurzor za nadaljnje sinteze. Pokazali smo, da je na zraku stabilna in določili temperaturo njenega razpada. Z računskimi metodami smo raziskali tudi obnašanje solvatnih molekul CH$_3$CN. V okviru tega dela je za podporo raziskovalnemu delu nastalo več računalniških programov, med drugim program za indeksiranje praškovnih difraktogramov z metodo Monte Carlo in program za obdelavo kristalnih struktur. Predstavljeno je njihovo delovanje ter splošne izkušnje s pisanjem programov in njihovim deljenjem z javnostjo.

Keywords

shranjevanje vodika;kovinski hidridi;kompleksni hidridi;borohidridi;zeolitna imidazolatna ogrodja;ZIF;računalniški programi;doktorske disertacije;

Data

Language: Slovenian
Year of publishing:
Typology: 2.08 - Doctoral Dissertation
Organization: UL FKKT - Faculty of Chemistry and Chemical Technology
Publisher: [M. Reberc]
UDC: 546.11:538.9(043.3)
COBISS: 174722051 Link will open in a new window
Views: 135
Downloads: 9
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Other data

Secondary language: English
Secondary title: Nanoconfinement of metal borohydrides in zeolitic imidazolate frameworks
Secondary abstract: The use of hydrogen as an energy carrier is one of the major scientific fields focused on lowering the carbon footprint of energetics. Even though the gravimetric energy density of hydrogen is very favourable, its volumetric density is low, necessitating the development of advanced storage materials and techniques. This work presents the synthesis and characterization of hydrogen storage material ZIF-8/LiBH$_4$, composed of microporous zeolitic imidazolate framework ZIF-8 (the compound of zinc cations and 2-methylimidazolate anion ligands) and nanoconfined borohydride LiBH$_4$. The material has a relatively low dehydrogenation onset temperature of about 120 ◦C, binds CO$_2$, and is not stable in air. Based on periodic DFT calculations, we have made predictions on the behaviour of the nanoconfined species in the pores of the framework. We have performed additional characterization of [Mg$_3${(Im)BH$_2$(Im)}$_6$(ImH)$_6$]·CH$_3$CN, a trinuclear magnesium complex compound, where magnesium centres are bridged by imidazole-substituted borohydride anions, and attempted to use it as a precursor for further syntheses. We have shown that the compound is stable in air and determined the temperature of its thermal decomposition. We have explored the behaviour of CH$_3$CN solvate molecules by DFT methods. Several computer programs were developed in this work to support the research process, including a program for powder pattern indexing using the Monte Carlo method and a program for crystal structure manipulation. The principles of their operations, as well as general experience with publicly sharing the programs, is presented.
Secondary keywords: zeolitic imidazolate frameworks;borohydrides;hydrogen storage;computer programs;Vodik;Disertacije;Shranjevanje;
Type (COBISS): Doctoral dissertation
Study programme: 1000381
Embargo end date (OpenAIRE): 1970-01-01
Thesis comment: Univ. v Ljubljani, Fak. za kemijo in kemijsko tehnologijo
Pages: VIII, 133 str.
ID: 21002721