The Role of Reducibility of PtGaO x -based Catalysts for Efficient and Durable Propane Dehydrogenation.

Although PtGaOx-containing catalysts are active and selective in the non-oxidative dehydrogenation of propane (PDH) to propylene, they suffer from rapid deactivation and, especially, inability to recover their initial performance in a series of PDH/oxidative regeneration cycles, characteristics that are highly relevant to commercialization. Herein, we identified reducibility of GaOx as the key descriptor affecting the above catalyst features. Oxidized GaOx species are more active than reduced GaOx in the recombination of two H species formed from propane, which is the rate-limiting step in the PDH reaction. This process is further accelerated by Pt. The reduction of GaOx with time on propane stream leads to catalyst deactivation. Easily reducible GaOx also tend to form PtGaOx under PDH conditions, from which Pt atoms present in fresh catalysts cannot be completely recovered during oxidative regeneration, which is detrimental to catalyst durability. Regardless of the reaction atmosphere, Pt single atoms exist on the surface of PtGaOx-containing catalysts with hardly reducible GaOx. Based on the knowledge derived, we developed a catalyst with 500 ppm Pt on the surface of mixed GaAlOx, which outperforms almost all previous PtGaOx-containing catalysts in terms of space-time yield of propylene formation and shows durable operation under industrially relevant conditions.