Low-temperature destruction of chlorinated hydrocarbons over lanthanide oxide based catalysts.

Introduction Chlorinated hydrocarbons (CHCs) have widespread industrial applications as, for example, lubricants, cleaning solvents, heat-transfer fluids, and intermediates of pharmaceuticals, herbicides and fungicides [1].The increasing volumes of CHCs released in the environment, together with the suspected toxicity and carcinogenic properties, have prompted researchers world-wide to find clean and effective routes for destroying CHCs. The method currently used most frequently is thermal incineration at temperatures higher than 1300°C [2]. The high incineration temperatures and related costs forced researchers to look for other solutions, preferably catalytic ones. Two main catalytic routes are reported in the literature. The first one is the oxidation of CHCs over supported noble metal catalysts, for example Pt and Pd, but the essential drawback of this method is the fast deactivation of the catalyst by Cl2 and HCl [3]. A second catalytic route is the hydrodechlorination in the presence of H2 into alkanes and HCl over supported Ni, Pd and Pt. However, also here, catalyst deactivation by chlorine poisoning and coke formation hampers their commercial introduction [4]. In this work, we report on a new and stable catalyst material based on the family of lanthanide oxides, which destroys different CHCs, such as CCl4, in the presence of steam at temperatures between 250 and 350°C [5].