Selection of mixed conducting oxides for oxidative dehydrogenation of propane with pulse experiments

In this study, propane pulse experiments at 550 °C are used as a method to select suitable oxides for operation of catalytic dense membrane reactor (CDMR) for selective oxidation of propane. La 2NiO 4+ δ is the most promising material for membrane application, provided that it is operated in the right window of reduction degree while PrBaCo 2O 5+ δ showed low selectivity to C 3H 6 and Ba 0.5Sr 0.5Co 0.8Fe 0.2O 3− δ appears to adsorb CO 2 by forming carbonates. [Display omitted] ▶ Pulse experiments can be used as method to select materials for operation of catalytic dense membrane reactors. ▶ Pulse experiments reveal the intrinsic activity and selectivity of lattice oxygen ions in the mixed oxides. ▶ La 2NiO 4 is the most promising material for membrane application, contrary to PrBaCo 2O 5 and Ba 0.5Sr 0.5Co 0.8Fe 0.2O 3. In this study, propane pulse experiments at 550 °C are used as a method to select suitable oxides for further operation of catalytic dense membrane reactor (CDMR) for oxidative dehydrogenation of propane. Ba 0.5Sr 0.5Co 0.8Fe 0.2O 3− δ (BSCF), La 2NiO 4+ δ (LN) and PrBaCo 2O 5+ δ (PBC) powders were used as model catalysts to explore the catalytic properties of membrane surfaces in terms of activity and selectivity. Furthermore, as propane pulses induce removal of oxygen from the sample, which is therefore depleted in oxygen by reducing the oxide, crucial information on the effect of the oxygen content in the samples ( i.e. the oxidation degree) on reactivity and selectivity is obtained. It will be shown that LN is the most promising material for membrane application, provided that it is operated in the optimal window of reduction degree, to ensure high selectivity towards C 3H 6. Contrary, PBC and BSCF are not suitable for CDMR. In fact, PBC showed low selectivity to C 3H 6 due to significant formation of CO 2, independent of the oxidation degree of the material and BSCF appears to adsorb CO 2 by forming carbonates, which might be detrimental for long term operation. However, pulse experiments revealed the remarkable stability of BSCF catalyst's activity towards CO 2 adsorption. Despite the presence of carbonate, the material preserved the ability to act as an oxygen source for propane and can be completely regenerated via oxidation. Additionally, the onset temperature in TPR appears to correlate well with the reactivity of lattice oxygen ions with propane, for the three materials studied.