Catalytic behavior of a novel SbRe2O6 compound in the selective oxidation of isobutylene: the key role of the cooperation between Sb4Re2O13 and Re2O7

The catalytic performance of a novel SbRe2O6 compound has been investigated in the selective oxidation of isobutylene to methacrolein at 673 K. The in itial reactivity of the catalyst strongly depended on catalyst pretreatment conditions. The catalyst was more active after pretreatments under more ox idative atmospheres. However, the activity of the catalyst always reached a n identical level at the steady state, independent of the pretreatment cond itions. Scanning electron microscopy and in situ confocal Raman microscopy revealed that the reactivity of SbRe2O6 was attributable to the presence at its surface of Re2O7 which benefitted from a cooperation with Sb4Re2O13. T he two phases resulted from a partial decomposition of SbRe2O6 in the prese nce of oxygen. When deposited on Sb4Re2O13, Re2O7 was stabilized and did no t volatilize under the reaction conditions. The phenomenon is likely the or igin of the cooperation between Sb4Re2O13 and Re2O7.