A novel trimetallic Pd-Cu-Fe/AC catalyst for hydrogen-assisted dechlorination of CFC-113: Enhancing catalytic activity and stability through intermetallic synergistic interaction

Abstract

The hydrogen-assisted dechlorination of 1, 1, 2-trichlorotrifluoroethane (CFC-113) to yield chlorotrifluoroethylene (CTFE) represents an efficient and environmentally alternative to zinc-mediated reductive dechlorination processes. Nevertheless, the industrial implementation of this technology has been constrained by suboptimal catalytic activity and stability in existing catalytic systems. Herein, we developed a high performance trimetallic Pd-Cu-Fe/AC catalyst via wet impregnation method. The optimal Pd-Cu-1.0Fe/AC catalyst exhibited 98.5% CFC-113 conversion, 92.6% CTFE selectivity and over 240 h lifetime under the harsh conditions of T=180 °C, C.T.=10 s and H₂/CFC-113=3/1, which to our knowledge was superior to all of reported catalysts to date. Due to the synergistic interaction of the Pd-Cu-Fe ternary system, the Pd-Cu-1.0Fe/AC catalysts demonstrated excellent catalytic activity, CTFE selectivity and stability. X-ray photoelectron spectroscopy and temperature-programmed reduction results revealed that the addition of Fe could reduce the extent to which Pd (0) was oxidized to Pd (II) and the reduction temperature of Pd (II) during the reaction process. Thermogravimetric analysis and N₂ adsorption/desorption experiments demonstrated that the formation of carbon deposition deactivated the Pd-Cu-Fe/AC catalyst, and the presence of Fe effectively reduced carbon deposition. The DFT calculations corroborated that Fe incorporation augmented the adsorption energy of CFC-113 and H₂ and while attenuating CTFE adsorption, thereby enhancing both catalytic activity and stability of the Pd-Cu-Fe/AC catalyst.