Oxidative dehydrogenation of ethane to ethylene: A promising CeO₂-ZrO₂-modified NiO-Al₂O₃/Ni-foam catalyst

From macro- to nano-engineering of a promising CeO₂-ZrO₂-doped NiO-Al₂O₃/Ni-foam catalyst has been demonstrated for the oxidative dehydrogenation of ethane to ethylene (ODE), through facial wet chemical etching of a Ni-foam followed post modification with CeO₂ and ZrO₂. The NiO-Al₂O₃/Ni-foam (denoted as NANF) achieved a high ethane conversion of 25.2% but with a very low ethylene selectivity of 43.1% at 450 °C. ZrO₂-doping of the NANF led to a remarkable improvement in the ethylene selectivity but serious deterioration of activity while the CeO₂-doping showed an opposite effect. Co-doping of the NANF using optimal amount of CeO₂ and ZrO₂ markedly promoted not only the activity but also the selectivity to ethylene. For example, over the 1CeO₂-5ZrO₂-NANF (CeO₂:1 wt%, ZrO₂:5 wt%) catalyst, a high ethane conversion of 40.3% was obtained with a 60.6% ethylene selectivity for a feed gas of C₂H₆/O₂/N₂ = 1/1/8 at 500 °C and a gas hourly space velocity of 18,000 cm³ g⁻¹ h⁻¹, corresponding to a high ethylene productivity of 510 g_Ethylene kg_cat⁻¹ h⁻¹. In nature, co-doping with CeO₂ and ZrO₂ synergistically tamed the NiO for selective H-abstraction of the ethane molecules other than over oxidation of them.