Pd supported catalyst for gas-phase 1,2-dichloroethane abatement: Efficiency and high selectivity towards oxygenated products

Abstract

Hydroxyapatite (HAP) support has been synthesised and impregnated with different amounts of Pd. The prepared Pd/HAP catalysts have been thoroughly characterised by BET, XRD, TEM, UV–visible–NIR, FTIR, XPS, CO2-TPD and NH 3-TPD techniques and tested in the DCE oxidation reaction. The characterisation of the catalysts has revealed a clear evolution of the Pd species structure, by increasing the Pd content, from highly dispersed tetrahedral coordinated Pd2+ to larger Pd2+ species particles adopting square planar geometry. The latter seems to be partially encapsulated by the HAP support. In DCE oxidation reaction the Pd/HAP system has shown an activity comparable to that of conventional system (Pd/alumina). However, the former has proved high selectivity towards the production of oxygenated products (COx (CO2 and CO)). Notably, in contrast to Pd/alumina, the DCE oxidation does not yield vinyl chloride intermediate product over Pd/HAP. This catalytic behaviour has been related to the moderate acidity of HAP compared to that of alumina together with its interaction with the Pd active phase. This report, then, considers that Pd(x)/HAP could be presented as a good alternative to those reported in the available literature.