Recovery and reduction of spent alumina-supported cobalt-molybdenum oxide catalyst via plasma sintering technique

A thermal plasma process for the recovery and reduction of the spent alumina-supported cobalt-molybdenum oxide catalyst (Co3O4-MoO2/Al2O3) was developed. The spent catalyst was sintered at > 1,500 K under plasma condition and the cobalt-molybdenum oxide therein was reduced to cobalt-molybdenum, which was proven by XRD and EDX. By application of SEM and GC technique, the organic tar on the surface of the spent catalyst was found to decomposed and converted to syngas (CO, CO2, and H-2), which might be the reducing agents in the process. A gasification mechanism for the generation of syngas and the reduction of cobalt-molybdenum oxide under plasma conditions was proposed.