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Na zeolitima strukturnih tipova FAU i MFI (ZSM-5) napravljene su modifikacije tijekom ili nakon sinteze kao bi se poboljšala njihova katalitička aktivnost. Pripremljeni uzorci su modificirani dodatkom mezoporoznog templata N,N,N-trimetilheksadekan-1-amonijeva bromida (CTAB) ili jetkani vodenom otopinom natrijeva hidroksida, kako bi se povećao broj mezopora u kristalima i olakšala difuzija reaktanata do aktivnog mjesta. Jakost aktivnog mjesta ugađana je kationskom zamjenom s ionima Mg2+ , Co2+, Ni2+ i Zn2+ (u vodenoj otopini i mehanokemijski). Utjecaj pojedinog metalnog kationa na broj i jakost Lewisovih i Brønstedovih kiselih mjesta u materijalu praćen je infracrvenom spektroskopijom u vakuumu pomoću adsorpcije probne molekule (deuterirani acetonitril). Broj pojedinih kiselih mjesta dobiven je integriranjem pojedinih krivulja nakon dekonvolucije spektra vezanog D3-acetonitrila, anjihova jakost određena je iz količine nakon zagrijavanja na 150, 200 i 300 °C. Na odabranim uzorcima napravljeni su katalitički testovi konverzije metanola u olefine. Modifications during and after sythesis were made on FAU and MFI (ZSM-5) zeolite type samples in order to enhance their catalytic activity. Prepared samples were modified with mesoporosity template N,N,N-Trimethylhexadecan-1-aminium bromide (CTAB) or etched with water solution of sodium hydroxide to increase the volume of mesopores in crystals and faciliate diffusion of reactnats to the active site. The strength of active sites was modified by cationic exchange with Mg2+ , Co2+ , Ni2+ and Zn2+ ions (in water solution and mechanochemicaly). Effect of metal cation on number and strength of Lewis and Brønsted acid sites was studied by infrared spectroscopy in vacuum with the adsorption of probe molecule (deuterated acetonitrile). The number of various types of acid sites was calculated from the integrated curves after deconvolution of spectra of adsorbed D3-acetonitrile, while their strength is determined after heating at 150, 200 and 300 °C. Catalytic tests of methanol to olefine conversion (MTO) were preformed on selected samples. |
