Studija izomerizacije n-butana na kiselim WO3/ZrO2 katalizatorima potaknutim niobijem i lantanom: aktivnost izomerizacije n-butana

The requirement for environmentally friendly catalysts for the isomerization of alkanes has prompted research on the tungstate-zirconia (WZ) system. The present work examines the activity and selectivity of lanthanum (La) promoted tungstate-zirconia (LWZ) and niobium (Nb) promoted tungstate-zirconia (NWZ) catalysts. In this study, 1 % La promoted WZ (1 % LWZ) and 1 % Nb promoted WZ (1 % NWZ) catalysts were investigated in isomerization of n-butane in the presence of hydrogen. The studied catalysts were characterized by different methods: nitrogen physisorption, temperature programmed desorption of NH3, thermogravimetric analysis, and X-ray diffraction. The catalytic activity and selectivity were significantly improved by the addition of 1 % Nb. The redox process in the Nb-containing catalyst (1 % NWZ) played a central role by providing the highest acidic sites (283.53 µmol g–1) with appropriate activation energies for the skeletal rearrangement of the reactant (n-butane). Furthermore, this study highlights the determining role of the transfer process of adsorbed species from ZrO2 to W as well as to the Nb environment. The conversion of n-butane (27.34 %) and the selectivity to i-butane (92.34 %) for NWZ were significantly higher than WZ and LWZ catalysts. The experimental results revealed that Nb was a more effective promoter than La.
Potreba za ekološki prihvatljivim katalizatorima primjenjivim za izomerizaciju alkana potaknuo je istraživanje sustava volframat-cirkonij (WZ). Ovaj rad ispituje aktivnost i selektivnost lantanom i niobijem potaknutih WZ katalizatora. U studiji je ispitana primjena WZ katalizatora potaknutih dodatkom 1 % lantana (1 % LWZ), odnosno 1 % niobija (1 % NWZ), u izomerizaciji n-butana u prisutnosti vodika. Karakterizacija je provedena različitim metodama: fizisorpcijom dušika, temperaturno programiranom desorpcijom amonijaka, termogravimetrijskom analizom i rendgenskom difrakcijskom analizom. Katalitička aktivnost i selektivnost znatno su poboljšani dodatkom 1 % niobija. Redoks-proces u katalizatoru koji je sadržavao niobij odigrao je glavnu ulogu osiguravajući najviše kiselih mjesta (283,53 µmol g–1) s odgovarajućom energijom aktivacije za preslagivanje n-butana. Konverzija n-butana (27,34 %) i selektivnost prema i-butanu (92,34 %) kod NWZ katalizatora bili su znatno veći nego kod WZ i LWZ katalizatora. Eksperimentalna istraživanja ukazuju učinkovitije poticanje dodatkom niobija u usporedbi s lantanom.