Studies on the modifications of Pd/Al2O3 and Pd/C systems to design highly active catalysts for hydrodechlorination of CFC-12 to HFC-32

Abstract

The article highlights the various modifications of the support for Pd catalysts to enhance the hydrodechlorination ability to synthesize dichlorodifluoromethane (HFC-32). The supports studied for the modification are either alumina (Al2O3) or carbon. In the modification of oxidic support, especially Al2O3, the main objective is to prevent to the maximum extent the transformation of oxidic support to the corresponding oxy/hydroxy fluorides due to the release of HF during the course of hydrodehalogenation reaction. Modification of Al2O3 support has been achieved by covering with carbon, called carbon-covered alumina (CCA), and simultaneous coverage with carbon and fluorine, called fluorinated carbon-covered alumina (FCCA). In the case of carbon as support, even though Pd/C exhibits good conversion in the hydrodehalogenation of CCl2F2, the selectivity towards HFC-32 is poor, and hence the modification of carbon support is aimed to enhance the selectivity towards HFC-32. Modification of carbon support has been achieved by incorporation of either MgO, ZrO2, or Al2O3.