Utjecaj načina priprave zeolita na jakost njihovih katalitički aktivnih mjesta

doctoral thesis

• Title (english): Influence of the way of preparation of zeolites on the strenght of their catalytic active sites
• Author: Ivana Landripet
• Mentor: Josip Bronić (mentor)
• Committee member: Mirta Rubčić (predsjednik povjerenstva)
• Committee member: Ana Šantić (član povjerenstva)
• Committee member: Jasminka Kontrec (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Chemistry); Zagreb
• Defense date and country: 2024, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Chemistry
• Universal decimal classification (UDC): 54 - Chemistry. Crystallography. Mineralogy

Abstract

Pripravljena su dva tipa zeolitne strukture: beta i mordenit. Iako su zeoliti mikroporozni materijali, njihova aktivnost u katalitičkim reakcijama je limitirana internom difuzijom reaktanata i produkata, a ista je poboljšana uvođenjem hijerarhijske strukture. Dio uzoraka modificiran je tijekom sinteze dodatkom ”mezoporoznog” templata – cetiltrietilamonijevog bromida, dok je drugi dio postsintetski obrađen nagrizanjem pomoću vodene otopine natrijevog hidroksida, tetrapropilamonijevog hidroksida i klorovodičnom kiselinom. Ovisno o omjeru silicija i aluminija te vrsti zeolita birana je otopina ili smjesa otopina za nagrizanje točno određenih koncentracija. Katalitička aktivnost i efikasnost katalizatora može se poboljšati povećanjem broja i podešavanjem jakosti katalitički aktivnih mjesta (Brønstedovih i Lewisovih kiselih mjesta), što je postignuto postsintetskim uvođenjem odabranih dvovalentnih kationa metala postupkom ionska izmjene popračene termičkom obradom. Količina, položaj i jakost katalitički aktivnih mjesta u materijalu praćen je Fourier-transformiranom infracrvenom spektroskopijom u vakuumu pomoću desorpcije probne molekule, deuteriranog acetonitrila.

Abstract (english)

Two types of zeolite structures were prepared: beta and mordenite. Although they are microporous materials by nature, intracrystalline diffusion of reactants and products of catalysis was limited, and is improved by introducing a hierarchical structure. Some samples were modified during synthesis by adding mesoporous template – cetyltrimethylammonium bromide, while the other samples was post–synthetically treated by etching using a solution of sodium hydroxide, tetrapropylammonium hydroxide, and hydrochloric acid. The etching solution or mixture of etching solutions was selected depending on the Si/Al ratio and zeolite topology. The catalytic activity and efficiency of the materials can be improved by increasing the number and adjusting the strength of catalytically active sites (Brønsted and Lewis acid sites), which can be achieved by ion–exchange with specific divalent metal cations. The number, position and strength of catalytically active sites was studied using vacuum Fourier-transform infrared spectroscopy of desorption of probe molecules, deuterated acetonitrile.

• Keywords: difuzija; ionska izmjena; katalitički aktivna mjesta; mordenit
• Keywords (english): catalytic acid sites; diffusion; ion–exchange; mordenite
• Language: croatian
• URN:NBN: urn:nbn:hr:217:559519
• Promotion: 2024
• Study programme: Title: Doctoral study; Study programme type: university; Study level: postgraduate; Academic / professional title: doktor/doktorica u području prirodnih znanosti (doktor/doktorica u području prirodnih znanosti)
• Type of resource: Text
• Extent: XV, 88 str. ; 30 cm
• File origin: Born digital
• Access conditions: Embargoed access; Embargo expiration date: 2025-04-22
• Created on: 2024-04-29 13:00:24