Catalytic activation of N2O on promoted NiO based materials: Valorization by oxidative dehydrogenation of ethane

• ODH of C 2 H 6 : Activity N 2 O ≈ O 2 . Selectivity to C 2 H 4 N 2 O > O 2 . • Correlation between ethylene selectivity and electrochemical properties. • Best promoters of NiO are those with high valence, especially Nb. • Selective catalysts have low density of acceptor defects and high surface resistance. • All NiO based catalysts are highly active for the N 2 O decomposition. N 2 O-assisted Oxidative Dehydrogenation (ODH) of ethane is an interesting way of simultaneously obtaining a highly valuable raw material (ethylene) and the functionalization of a greenhouse gas (N 2 O). Unfortunately, over most of the catalytic systems, this reaction presents two main drawbacks: i) high yields to ethylene have hardly been reported; and ii) the catalytic activity highly decreases when replacing molecular oxygen by N 2 O. In the present article, it will be shown that with promoted NiO catalysts, and using N 2 O, high activity, comparable with that of conventional O 2 -assisted ODH of ethane, is achieved. Furthermore, the use of the appropriate dopant, such as niobium, allows high ethylene yields (40 %), with a selectivity to ethylene of 72 % at 55 % ethane conversion. Overall, the catalytic results obtained indicate that the presence/absence and the nature of the promoter determines the catalytic performance of NiO based catalysts and the selectivity to ethylene can be explained on the basis of the electrochemical properties of the catalysts, correlating with parameters such as the density of acceptor defects (cationic vacancies) and the charge-transfer resistance at the interfacial active sites of the catalysts. Interestingly, the most selective catalyst (i.e., Nb-doped NiO) is highly robust as it presents stable catalytic performance after 24 h online and Ni 2+ species are not reduced to Ni 0 even working at high temperatures in N 2 O-free conditions.