Selective hydrodechlorination of 1,2-dichloroethane to ethylene over Pd-Ag/Al2O3 catalysts prepared by surface reduction

Alumina supported Pd-Ag and (Cu) bimetallic catalysts (denoted as sr -Pd-Ag/Al 2 O 3 or sr -Pd-Cu/Al 2 O 3 ) with varied Pd/Ag (or Cu) ratios were prepared using the surface reduction method, and the gas-phase catalytic hydrodechlorination of 1,2-dichloroethane over the catalysts were investigated. For comparison, Pd-Ag bimetallic catalysts were prepared by the conventional co-impregnation method (denoted as im -Pd-Ag/Al 2 O 3 ). The catalysts were characterized by N 2 adsorption, X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and CO chemisorption. Characterization results indicated that surface reduction led to selective deposition of metallic Ag on the surface of Pd particles, while Pd and Ag just disorderly mixed in the catalyst prepared by impregnation method. Therefore, sr -Pd-Ag/Al 2 O 3 exhibited a higher ethylene selectivity than im -Pd-Ag/Al 2 O 3 for hydrodechlorination of 1,2-dichloroethane at a similar Ag loading amount. Moreover, among sr -Pd-Ag/Al 2 O 3 , sr -Pd-Cu/Al 2 O 3 and im -Pd-Ag/Al 2 O 3 catalysts, the ethylene selectivity decreased over these catalysts following the order: sr -Pd-Ag/Al 2 O 3  >  sr -Pd-Cu/Al 2 O 3  >  im -Pd-Ag/Al 2 O 3 . The present results indicate that surface reduction can be used as a potential method to synthesize catalyst with enhanced ethylene selectivity in hydrodechlorination of 1,2-dichloroethane.