Catalysis Today, Vol.361, 50-56, 2021
Oxidative dehydrogenation of ethane over M1 MoVNbTeO catalysts modified by the addition of Nd, Mn, Ga or Ge
Modification by Nd, Mn, Ga, and Ge substantially affect both physicochemical and catalytic properties of MoVNbTeO oxides in the oxidative dehydrogenation of ethane (ODE). The introduction of modifying additives changes the content of the M1 phase, surface acidity, and surface composition. It does not have an infiuence on the state of Mo, V, Nb, and Te on catalyst surface, but it induces surface enrichment (Ga, Mn) or depletion (Ge, Nd) by the modifying element. All of these additives have positive effects on catalytic properties at the M/Mo (M = modifying element) ratio of 0.0075 divided by 0.025. They exhibit an increase of activity and prevent ethylene over-oxidation. The relationship between the rate constant of total ethane transformation and the M1 content confirms that this phase is active in ODE. The correlation between ethylene selectivity and the relative number of intermediate acid sites is revealed, indicating the role of surface acidity on ethylene over-oxidation.