The effect of V in La2Ni1−xVxO4+1.5x+δ on selective oxidative dehydrogenation of propane: Stabilization of lattice oxygen

In this study, the non-stoichiometric redox compounds La2NiO4+δ and La2Ni0.9V0.1O4.15+δ have been tested as an oxidant in selective oxidation of propane in pulse experiments at temperatures between 450 and 650 °C. The oxygen contents in the samples at different temperatures were calculated based on back-titration with O2 pulses as well as on TGA. In the case of La2Ni0.9V0.1O4.15+δ over-stoichiometric oxygen was the only active species, responsible for the formation of CO2, C3H6, C2H4 and CH4 while pulsing propane at all investigated temperatures. Contrary, the reactive species in La2NiO4+δ changed from over-stoichiometric oxygen only at 450 °C, to both over-stoichiometric and lattice oxygen at 550 °C, to lattice oxygen only at 650 °C. The activation of lattice oxygen and the consequent formation of Ni metal were detrimental for selectivity to propylene as formation of COx, CH4 and coke mainly occurred and no olefins were formed.

The non-stoichiometric redox compounds La2NiO4+δ and La2Ni0.9V0.1O4.15+δ have been tested as oxidants in selective oxidation of propane in pulse experiments at temperatures between 450 and 650 °C. The role of vanadium was crucial to stabilize both over-stoichiometric and lattice oxygen, diminishing the oxygen loss and delaying the consequent formation of Ni metal, detrimental for selectivity towards propylene.Figure optionsDownload high-quality image (74 K)Download as PowerPoint slideResearch highlights▶ Addition of V to La2NiO4 causes that over-stoichiometric oxygen-ions is the exclusive active species when pulsing and oxidizing propane. ▶ The rate of oxygen-ion removal, i.e. reduction of the oxide, is retarded and formation of Ni0 is prevented.