Table 2: Different identified phases in the calcined catalysts with different aging times.

Aging time (minute)Phases

0 MnO (cubic), FeO (cubic), (orthorhombic), (monoclinic)
30 MnO (cubic), FeO (cubic), (orthorhombic), (monoclinic)
60 MnO (cubic), FeO (cubic), (orthorhombic), (monoclinic)
120 (monoclinic), MnO (cubic), FeO (cubic)
180 MnO (cubic), FeO (cubic), (monoclinic), Fe (cubic)
300 (monoclinic), MnO (cubic), FeO (cubic)