Catalytic performance of chlorinated Ce/Zr mixed oxides for Cl-VOC oxidation

Contamination by chlorinated volatile organic compounds (Cl-VOCs) is currently a matter of considerable concern, since these compounds are considered as dangerous for their effect on human health and the environment. Catalytic oxidation appears as an attractive approach for the destruction of these hazardous compounds. Although the development of catalysts to produce CO(2) and HCl is a topic of demanding interest, less consideration has been given to examining the catalytic stability during extended time on stream. Indeed the presence of HCl and/or Cl(2) may induce alterations in the behaviour of the catalysts. The main scope of this work is to evaluate the catalytic behaviour of a series of Ce/Zr mixed oxides in the gas-phase oxidation of 1,2-dichloroethane submitted to a previous chlorination followed by calcination (550 degrees C for 4 hours in air) or by reduction (550 degrees C with 5%H(2)/Ar for 1 hour) and calcination. Chlorination led to remarkable changes in acidity and redox properties, which were shown to be the key catalytic properties of these catalysts for this reaction. On one hand, the chlorine reinforced the acidity of the catalytic surface. In contrast, redox properties were negatively impacted. However, these alterations were partially compensated leading to a slightly lower activity of chlorinated samples. It could therefore be concluded that Ce/Zr catalysts resulted in significant resistance to deactivation by chlorine poisoning, thereby showing a great potential for this environmental application, not only in terms of low-temperature Cl-VOC conversion, but also of stability during extended periods of time on stream.