Reduction processes in Cu/SiO2, Co/SiO2, and CuCo/SiO2 catalysts

► CuO and Co3O4 reduce via stepwise processes in H2 atmosphere. ► Some CuO in CuCo/SiO2 (but not in Cu/SiO2) is in an amorphous form. ► Amorphous CuO reduces at lower temperature than crystalline CuO. ► Cobalt oxides are more reducible on CuCo/SiO2 than on Co/SiO2.