Total oxidation of ethanol over layered double hydroxide-related mixed oxide catalysts: Effect of cation composition

Ethanol total oxidation over mixed oxide catalysts containing various transition metal cations was studied. The M-II-M-III layered double hydroxide (LDH) precursors with M-II/Mn-III molar ratio of 2 (M-II= Cu, Co, Ni, Cu-Ni, Cu-Co, and Co-Ni; M-III = Mn or Al) were prepared by coprecipitation of nitrate solutions. The ternary mixed oxides containing Mn were more active than the binary Cu-Mn, Co-Mn, and Ni-Mn ones as well as the ternary Al-containing catalysts; the Cu-Ni-Mn mixed oxide was the most active. The catalytic activity increased with increasing amount of easily reducible components and amount of oxygen desorbed from catalysts surface at lower temperatures (up to 500 degrees C). Main byproduct of the ethanol oxidation was acetaldehyde. Ethanol oxidation over Al-containing catalysts produced lower amounts of acetaldehyde than that over the catalysts comprising Mn; both the Cu-Ni-Mn and Co-Ni-Mn catalysts showed the lowest temperatures of acetaldehyde disappearance. (C) 2015 Published by Elsevier B.V.