The effect of oxygen vacancies on the coordinatively unsaturated Al-O acid-base pairs for propane dehydrogenation

Recently, the coordinatively unsaturated metal-O Lewis acid-base pairs of metal oxides are found to be able to activate the C–H bond of light alkane efficiently. For the inert crystal Al2O3, we found that the surface oxygen vacancy amount of Al2O3 can be controlled by pretreatment of CO reduction, and the nearby coordinatively unsaturated Al-O (Alcu-O) pairs can effectively catalyze propane dehydrogenation (PDH). The C3H6 formation rate of γ/δ-Al2O3 is in line with the concentration of oxygen vacancies. The experiments and DFT calculations illuminate the importance of oxygen vacancy on the surface of Al2O3 for PDH reaction. The consumption of lattice oxygen reduces the one coordination number of the bonding Al, the formed Alcu-O as defective acid-base pairs, can be an effective way to tune the adsorption energy of the intermediates and the barriers of key steps (the first CH activation and H2 formation) to enhance the performance of PDH through both site-dependent concerted and stepwise mechanisms.