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

The C 3 H 6 formation rate of γ/δ,-Al 2 O 3 catalyst is in line with the concentration of oxygen vacancies. The coordinatively unsaturated Al-O Lewis acid−base pairs close to oxygen vacancy are responsible for the propane dehydrogenation. [Display omitted] • The surface oxygen vacancy amount of Al 2 O 3 can be controlled by CO reduction. • The r(C 3 H 6) of γ/δ-Al 2 O 3 is in line with the concentration of oxygen vacancies. • The consumption of lattice oxygen forms (Al cus -O) pairs for propane dehydrogenation. • The different Al cus -O pairs tune the adsorption energy and the barriers of key steps. 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 Al 2 O 3 , we found that the surface oxygen vacancy amount of Al 2 O 3 can be controlled by pretreatment of CO reduction, and the nearby coordinatively unsaturated Al-O (Al cu -O) pairs can effectively catalyze propane dehydrogenation (PDH). The C 3 H 6 formation rate of γ/δ-Al 2 O 3 is in line with the concentration of oxygen vacancies. The experiments and DFT calculations illuminate the importance of oxygen vacancy on the surface of Al 2 O 3 for PDH reaction. The consumption of lattice oxygen reduces the one coordination number of the bonding Al, the formed Al cu -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 C H activation and H 2 formation) to enhance the performance of PDH through both site-dependent concerted and stepwise mechanisms. [ABSTRACT FROM AUTHOR]