In this work we have studied for the first time the catalytic activity for the oxidation of trichloroethylene (TCE) of Cu and Co beta zeolites. The results show that they are active and selective towards CO 2, obtaining a better selectivity than that reached with conventional H-zeolites. The copper and cobalt zeolites have been prepared by different methods. It was found that their activity depend on the metal and on the preparation procedure. The most active catalyst was the Cu-BEA prepared by ion exchange (T 50% = 310°C and T 90% = 360°C). This catalyst has the highest ammonia adsorption capacity (as a measurement of the acidity) and it was the only tested material in which the Me 2+ was completely reduced in a standard H 2-TPR experiment (indicative of its important redox properties). Thus, the enhanced activity of the Cu-exchanged zeolite was associated to the presence of strong acid sites in the zeolite and to the redox properties of the copper ion exchanged. The catalyst was stable at 300°C for almost 70 hours without any important deactivation. This was related to the oxidative properties of the copper that avoid the formation of coke on the strong acid sites of the zeolite. On the other hand, zeolites with the transition metal incorporated into the zeolite framework by hydrothermal synthesis showed lower catalytic activity, probably because the formation of small oxide particles with much less interaction with the silicate framework, that results in a lower redox activity of the transition metals. It has been shown that a proper combination of acidity, redox properties and metal-zeolite interaction is necessary in order to prepare an active and selective zeolite catalyst for the TCE oxidation.

Different Cu/(Mg or Ni)/Al mixed oxides based on hydrotalcite-like compounds have been studied for the catalytic oxidation of trichloroethylene. The catalysts have been synthesized and characterized by different techniques such as N2-adsorption, inductively coupled plasma (ICP), X-ray diffraction, and temperature-programmed reduction (TPR). It has been shown that the activity for the catalytic abatement of trichloroethylene depends on the presence of metals with redox properties in the catalyst composition. The best results have been obtained with containing copper mixed oxides, although there is no direct correspondence between the copper content and the catalyst activity. These catalysts are highly active and selective, CO2 and HCl being the main reaction products. A mechanism for the reaction has been proposed.

ElsevierBlanch Raga, N.; Palomares Gimeno, AE.; Martínez Triguero, LJ.; Puche Panadero, M.; Fetter, G.; Bosch, P. (2014)

The enhanced activity has been related to the remarkable higher surface area of the catalyst and to the catalyst composition which influences the acid characteristics as well as the reducibility and reoxidation of the catalysts. The importance of the oxygen dissociation on the catalyst surface and the diffusion of oxygen species through the catalyst are also discussed.