369199 V2O5-Nb/La-Al2O3 Catalysts for Oxidative Dehydrogenation of Ethane to Ethylene
The aim of this study is to investigate oxidative dehydrogenation (ODH) of ethane to ethylene in absence of gas phase oxygen using multimetallic V2O5-Nb/La-Al2O3 catalysts. In the catalyst formulation, La is used to modify γ-Al2O3, stabilizing bulk phase transformation of γ-Al2O3. A small amount of Nb is used as a promoter of the main active V2O5 species.
Catalysts were prepared by using an incipient wetness technique. V2O5 was loaded on La modfied γ-Al2O3 (260 m2/g). Before V2O5 loading the support γ-Al2O3 was modified with La. The prepared catalysts were characterized using various physicochemical techniques in order to understand the different aspects of their performances including the reducibility, oxygen carrying capacity, stability and phase transformation under repeated redox cycles.
Temperature programmed reduction (TPR) evaluation shows that Nb-V2O5/La-Al2O3 catalyst is very stable over repeated reduction and oxidation cycles. In each cycle the amount of hydrogen consumption remains stable approximately at 80 cc/g catalyst. XRD analysis indicates that V2O5 on catalysts is an amorphous phase up to 10 % V loading. The pulse chemisorption show a good metal dispersion on the La modified support. SEM and EDX results reveal that La, Nb and V2O5 are present on the support surface as mono-vanadate and poly-vanadate in amorphous phase which further confirmed by XRD peak analysis.
The gas phase oxygen free ODH of ethane in the fluidized CREC Riser Simulator displays that approximately 30 % ethane conversion can be achieved in very short contact time reactions. The oxygen free (gas phase) ODH also found favorable to obtain high ethylene selectivity (upto 85 %). The Nb-V2O5/La-Al2O3 catalyst also shows stable performance in the repeated ODH-regeneration cycles which is consistent to cyclic TPR/TPO results.
Acknowledgement: We acknowledge the financial support by KACST research grant number ARP-30-252