High-temperature oxidation of LnCu2 intermetallics and their catalytic behavior in 4-methyl-2-pentanol decomposition

The air-oxidation of the intermetallic compounds LaCu2, CeCu2, PrCu2, and NdCu2 was followed by thermogravimetry. The mass uptake occurred over a wide range of temperature (423-1100 K), leading to two stoichiometrics according to the lanthanide; CeCu2O4 and LnCu2O3.5 (Ln = La, Pr, Nd). The characterization by powder X-ray diffraction, scanning electron microscopy/energy dispersive X-ray analysis, and surface area measurements showed that segregation took place with the formation of CuO along with CeO2 or Ln2CuO4 (Ln = La, Pr, Nd). Therefore, the oxidized intermetallics are better described by the formulas CeO2·2CuO and Ln2CuO4·3CuO. The oxidation process noticeably increased the surface areas and promoted CuO migration to the surface. These systems exhibited selectivities in 4-methyl-2-pentanol decomposition, which are associated with the lanthanide. 34 refs., 4 figs., 3 tabs