Study of CuCl 2 Supported on SiO 2 and Al 2 O 3

The nature and stability of surface species of CuCl 2 supported on α‐Al 2 O 3 , γ‐Al 2 O 3 , and SiO 2 were investigated by using X‐ray diffraction techniques and reflectance spectroscopy. No specific chemical interaction of CuCl 2 is observed on an inert α‐Al 2 O 3 support, as opposed to hydrated carriers as SiO 2 and γ‐Al 2 O 3 . On these supports the coordination sphere of Cu 2+ consists of surface groups (OH − or O − at drying and activation, resp.), H 2 O and Cl − , with the H 2 O ligands decreasing in concentration in the process of impregnation, drying and calcination. γ‐Al 2 O 3 samples, calcined at 400°C, show γ‐Cu 2 (OH) 3 Cl as opposed to CuAl 2 O 4 at higher temperatures. The absence of Cu 2 (OH) 3 Cl on SiO 2 ‐supported samples is related to the acid‐base characteristics of the carriers. The various supports can be arranged in the following order of stability of the complexes formed: γ‐Al 2 O 3 > SiO 2 ≫ ‐Al 2 O 3 .