Structure-activity relationships for propane oxidative dehydrogenation by anatase-supported vanadium oxide monomers and dimers

To understand the importance of the effect of molecular structure on reactivity, we have studied the activity of anatase TiO₂ (0 0 1) supported VO_x catalytic sites for propane oxidative dehydrogenation (ODH). First, possible structures of monomeric and dimeric VO_x species on anatase (0 0 1) after VO₄H₃ grafting and water elimination were determined. We then studied the conversion reaction of propane to propanol by the supported VO_x to elucidate the structure-reactivity relationship. The coordination number of the vanadium atom was the key structural parameter in predicting the catalytic activity. This key structural difference alone resulted in an increase of up to 800 times in the reaction rate of CH bond activation (rate-determining for propane ODH) for the various vanadium oxide species at 600 K. These results demonstrate the remarkable sensitivity of the catalytic site activity to its geometric structure and its implications for achieving optimal catalyst performance.