Inhibiting the sintering of supported metal catalysts for CO 2 methanation is still a great challenge, especially at high temperature. Herein, the novel catalyst was prepared by using high entropy spinel oxide (Co 0.2 Ni 0.2 Mg 0.2 Zn 0.2 Mn 0.2 )Al 2 O 4 (HEO) as precursor, which was reduced in a hydrogen atmosphere to obtain Ni−Co alloys supported on Al 2 O 3 -covered (Mg 0.2 Zn 0.2 Mn 0.2 )-Al 1.2 O 2.4 spinel oxide with a core−shell structure. This catalyst exhibited excellent stability at 550 °C for 320 h. Characterization results showed that the formation of the core−shell structure due to uniform element dispersion of the HEO precursor led to a larger interface, closer contact, and stronger interaction between the core and shell, which ensured the stability of the shell Al 2 O 3 and further stabilized Ni−Co alloys. However, the catalyst derived from the mixed spinel oxide precursor was unable to achieve the core−shell structure support due to uneven element dispersion, which exhibited inferior stability. This study has successful extended the application of high entropy oxides.

Inhibiting the sintering of Cu-based catalysts for CO 2 reverse water−gas shift (RWGS) reaction is still a great challenge. Herein, Cu−Al spinel supported on Al 2 O 3 was prepared by a surface solid reaction and used as a precursor to obtain Cu particles with high dispersions and high stabilities. Due to the high dispersions of Cu cations in Cu−Al spinel, strong chemical interactions between Cu particles and newly generated Al 2 O 3 , and the isolation effects of Al 2 O 3 particles, Cu particles derived from Cu−Al spinel exhibited smaller sizes after H 2 reduction, excellent activities, and 300 h stabilities for RWGS reactions. However, Cu particles obtained from the supported CuO precursor showed much larger particle sizes (>70 nm) and inferior activities and stabilities for CO 2 reverse water−gas shift reaction. This study made a successful attempt to enhance the activities and stabilities of Cu-based catalysts through changing the oxide precursor.