Revealing fundamentals affecting activity and product selectivity in non-oxidative propane dehydrogenation over bare Al2O3

A detailed study was carried out to elucidate the factors affecting the activity and, particularly, selectivity of bare Al2O3 in the non-oxidative propane dehydrogenation (PDH) to propene under industrially relevant conditions. A series of samples were synthesized by a precipitation method upon varying the ratio of OH−/Al3+ in the solution. This ratio was established to affect the ability of Al2O3 to form aluminium cations with lower coordination (Alcus) than regular surface Al3+ sites. Such defective sites show higher activity for propene formation and lower ability for coke formation. In addition to the preparation method, the kind of reducing agent for Al2O3 is decisive for creation of the desired defects, with CO showing higher reactivity owing to its ability to react with surface OH groups.