Effect of cobalt precursors on the dispersion, reduction, and CO oxidation of CoO x/γ-Al 2O 3 catalysts calcined in N 2

Abstract

The present work tentatively investigated the effect of cobalt precursors (cobalt acetate and cobalt nitrate) on the physicochemical properties of CoO x /γ-Al 2O 3 catalysts calcined in N 2. XRD, Raman, XPS, FTIR, and UV–vis DRS results suggested that CoO/γ-Al 2O 3 was obtained from cobalt acetate precursors and CoO was dispersed on γ-Al 2O 3 below its dispersion capacity of 1.50 mmol/(100 m 2 γ-Al 2O 3), whereas Co 3O 4/γ-Al 2O 3 was obtained from cobalt nitrate precursors and Co 3O 4 preferred to agglomerate above the dispersion capacity of 0.15 mmol/(100 m 2 γ-Al 2O 3). Compared with Co 3O 4/γ-Al 2O 3, CoO/γ-Al 2O 3 catalysts were difficult to be reduced and easy to desorb oxygen species at low temperatures and presented high activities for CO oxidation as proved by H 2-TPR, O 2-TPD, and CO oxidation model reaction results. A surface incorporation model was proposed to explain the dispersion and reduction properties of CoO/γ-Al 2O 3 catalysts.