Electron paramagnetic resonance study of interaction between MoO3 and propene

Interaction of MoO3 with propene at the temperature range 420–520 K results in the appearance of several EPR signals. Four of them have been assigned to different Mo(V) centres, one to localised conduction electrons. The analysis of the signals' parameters and the sequence of their appearance allows the conclusion that the allyl species formed in the first stage of interaction are adsorbed in a certain distance from the simultaneously created Mo(V). This is an important finding, modifying the existing hypotheses on the reaction mechanism. In the next stage of reduction the precursors of shear structures are formed due to the removal of lattice oxygen by the desorbing oxidation products.