High CO reactivity of cobalt oxide catalyst deposited on alumina powders by rotary chemical vapor deposition

•Co3O4 supported on α-Al2O3 of 0.6 m2 g−1 were prepared by a rotary CVD method.•Co3O4 were deposited with sizes of 5–10 nm, and contents of 0.10–0.36 wt%.•The Co3O4 dispersion was very high and controlled with deposition duration.•Co3O4/α-Al2O3 exhibited very high CO oxidation activity despite its low contents.•This is a new method for high dispersibility even with low surface area supports. Cobalt oxide (Co3O4) catalysts supported on α-Al2O3 were prepared by a rotary chemical vapor deposition (CVD) method. Although the specific surface area of α-Al2O3 powders was extremely low, finely dispersed nanoparticles of Co3O4 with the size of several nanometers were formed on the support under the deposition condition of 370 °C for 30–120 min. Despite the minimal Co3O4 content of 0.10–0.36 wt%, the Co3O4/α-Al2O3 exhibited the significant catalytic activity for CO oxidation; the temperatures at which the conversion of CO reached 20% (T20) were 157–189 °C and the conversion reached 100% until 300 °C. Thus, a rotary CVD method can finely control the dispersibility of Co3O4 on α-Al2O3 surface, which was related to high catalytic activity.