https://doi.org/10.15255/KUI.2021.078
Published: Kem. Ind. 71 (7-8) (2022) 439–446
Paper reference number: KUI-78/2021
Paper type: Original scientific paper
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Study of n-Butane Isomerization on Acid Catalysts Niobium and Lanthanum Promoted Tungstated Zirconia: n-Butane Isomerization Activity

Z. Mohamed Seghir, M. Djennad, R. Schomäcker and M. R. Ghezzar

Abstract

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.

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Keywords

tungstated zirconia, n-butane isomerization, niobium, lanthanum, acidity