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.