Structural effect of ZnZr2Ox catalysts on dehydrogenation: Mechanism of cracking

Abstract

The present work revealed the mechanism of various reactions during the dehydrogenation of propane, then elucidated the structural effects of binary ZnZr₂O_x on the catalytic performance of catalysts. ZnZr₂O_x with various crystal phases and crystal sizes were prepared. It revealed that the structure of catalysts affected the formation of oxygen vacancies (O_v) thus tuning the active sites of various reactions and influenced the diffusion of gas, all of which significantly influence catalytic performance. The ZnZr₂O_x possessing a tetragonal ZrO₂ phase exhibited superior catalytic performance compared to that possessing a ZnO phase. Furthermore, the smaller the grain, the higher the reducibility leading to more O_v accompanying by more active sites of hydrogenation and less active sites of cracking, and the lower diffusion resistance, resulting in high catalytic performance. Therefore, the smallest ZnZr2-Hy(AP) nano-particles displayed the highest catalytic activity with respect to propene selectivity and stability.