Stability of ZnAl2O4 catalyst for reverse-water-gas-shift reaction (RWGSR)

Reverse-Water-Gas-Shift reaction (RWGSR) was carried out over the ZnO, Al2O3, and ZnO/Al2O3 catalysts at the temperature range from 400 to 700 degreesC. The ZnO showed good specific reaction activity but this catalyst was deactivated. All the catalysts except the ZnO/Al2O3 catalyst (850 degreesC) showed low stability for the RWGSR and was deactivated at the reaction temperature of 600 degreesC. The ZnO/Al2O3 catalyst calcined at 850 degreesC was stable during 210 Ins under the reaction conditions of 600 degreesC and 150,000 GHSV, showing CO selectivity of 100% even at the pressure of 5 atm. The high stability of the ZnO/Al2O3 catalyst (850 degreesC) was attributed to the prevention of ZnO reduction by the formation of ZnAl2O4 spinel structure. The spinel structure of ZnAl2O4 phase in the ZnO/Al2O3 catalyst calcined at 850 degreesC was confirmed by XRD and electron diffraction.