Coupling oxygen storage and catalysis to design redox catalysts for efficient ethylbenzene dehydrogenation†

Abstract

Chemical looping oxidative dehydrogenation (CL-ODH) is an alternative pathway for alkene production. Herein, we fabricated a series of MFe₂O₄@KFeO (M = Cu, Zn, or Mn) core–shell structured redox catalysts for the conversion of ethylbenzene CL-ODH into styrene. Owing to a high oxygen storage capacity of CuFe₂O₄ around the dehydrogenation temperature (600 °C), CuFe₂O₄@KFeO exhibits the highest ODH reactivity among the three transition metal-based composites, achieving an ethylbenzene conversion of 65% with a stable styrene selectivity of 91% in 50 ethylbenzene/O₂ redox cycles. Compared with the traditional process, ethylbenzene CL-ODH technology shows great potential for energy saving and safety. The KFeO catalytic shell enables modification of oxygen donation ability and transforms the nonselective oxygen of CuFe₂O₄ into well-matched lattice oxygen for selective hydrogen combustion (SHC) during ethylbenzene dehydrogenation. The coupling effect of the catalytic shell (KFeO) and oxygen storage core (CuFe₂O₄) is responsible for superior ODH performance, enabling catalytic dehydrogenation and SHC to pair in a spatiotemporal coordination mode. This study offers a new insight into coupling oxygen storage and catalysis via a mutually beneficial effect. The successful design of core–shell-structured redox catalysts for CL-ODH processes will offer an efficient and affordable solution for producing olefin.