Oxidative dehydrogenation of ethane: A study over the structure and robustness of Ni-W-O catalysts

The robustness of one selected Ni-W-O catalyst has been studied in the oxidative dehydrogenation of ethane. This catalyst initially deactivates for the first 10 h online decreasing 15% of its catalytic activity compared to its initial stable catalytic activity. However from 10 to 60 h online the catalytic activity keeps almost stable. On the other hand, it has been shown that the Ni-W-O catalyst cannot tolerate an oxygen-free atmosphere (C-2 and He) as nickel oxide is transformed into metallic nickel. Methane and hydrogen as well as abundant coke were formed on the surface of the catalyst in these O-free conditions. However a re-calcination in air leads to the removal of coke, the catalytic performance in the oxidative dehydrogenation of ethane being almost completely restored. Ni-W-O catalysts are active and selective in the oxidative dehydrogenation of ethane. However, their catalytic performance highly depends on the catalyst composition. At the present paper we have prepared Ni-W-O catalysts with an optimal W/(Ni + W) ratio using different procedures. It will be shown that the preparation method employed determines the Ni- and W-species formed in the catalysts and consequently the catalytic performance. (C) 2013 Elsevier B.V. All rights reserved.