Utilizing cationic defect and Mo doping on ZnAl2O4 spinel catalyst to enhance isobutane dehydrogenation

Abstract

Spinel-type ZnAl₂O₄ is considered as a promising and efficient alkane dehydrogenation catalyst due to its high thermal stability and low acidity. Nevertheless, the activity of ZnAl₂O₄ spinel catalyst still needs to be improved. Herein, ZnAl₂O₄-based spinel catalysts with Zn cation defect and doping with Mo were fabricated via solid-state grinding method. Among these, the Zn_0.9Al_1.99Mo_0.01O₄ catalyst presented the highest isobutane conversion of 67.51 %, isobutene selectivity of 95.29 % and isobutene yield of 64.33 % with excellent thermal stability. A series of characterizations and theoretical calculations were developed to research the physicochemical properties and adsorption behaviors of the catalysts. The results demonstrated that the Zn cation defect and doping with Mo resulted in a downshift of the d-band center of ZnAl₂O₄, which not only caused the desorption of isobutene but also favored the flat adsorption orientation of isobutane. This study provides a method to improve the isobutane dehydrogenation performance via the introduction of Zn cation defect and Mo doping.