Alumina-Supported Copper Chloride: 4. Effect of Exposure to O2 and HCl

Abstract A complete catalytic cycle was performed on CuCl 2 /Al 2 O 3 catalyst for ethylene oxychlorination at 500 K. X-ray absorption near-edge spectroscopy, extended X-ray absorption fine structure, electron paramagnetic resonance, and IR of adsorbed CO were used to demonstrate that the ethylene oxychlorination reaction, C 2 H 4 +2HCl+1/2 O 2 →C 2 H 4 Cl 2 +H 2 O, follows a three-step mechanism: (i) reduction of CuCl 2 to CuCl (2CuCl 2 +C 2 H 4 →C 2 H 4 Cl 2 +2CuCl), (ii) oxidation of CuCl to give an oxychloride (2CuCl+1/2 O 2 →Cu 2 OCl 2 ), and (iii) closure of the catalytic circle by rechlorination with HCl, restoring the original CuCl 2 (Cu 2 OCl 2 +2HCl→2CuCl 2 +H 2 O). The dispersing/sintering effect of the different reagents on the active phase has been also investigated.