Abstract
Catalytic oxidation of trichloroethylene (TCE) in heterogeneous phase (gas-solid) is an effective strategy for the conversion of this pollutant in less harmful compounds, namely CO2, CO and HCl. In this work, we have studied the use of mayenite, a cost-effective material, as an active catalyst for the TCE conversion. In particular, we have assessed the influence of the mayenite synthesis method (hydrothermal, sol-gel and ceramic) on the reaction performance. The materials have been characterized by different techniques, such as XRD, N2-sorption (BET), TPR, Raman spectroscopy, FESEM-EDX and TEM. The analysis of the light-off curves and product distribution, has shown that the use of the hydrothermal method for the mayenite synthesis results in the most active and selective catalyst. This has been related with a higher surface area and with a higher concentration of oxygen anions in the mayenite prepared by this method. It has been found that the presence of water in the stream do not influence the catalytic performance of the material. A mechanism for the reaction and for the partial deactivation of the catalyst has been proposed.
Highlights
Trichloroethylene (TCE) is a common chlorinated volatile organic compound (VOC), widely employed until the eighties as organic solvent in industrial dry-cleaning applications and in painting and coating manufactures[1]
Comparing the X-ray diffraction patterns (XRD) patterns, it can be observed that the mayenite synthesized by the hydrothermal process (Maye HA) showed broader and less intense peaks with respect to the other samples
Mayenite was prepared by different methods to evaluate the influence of the preparation method on the catalytic activity for TCE oxidation
Summary
According to the literature[30] the complete reduction of extra-framework anions in the mayenite requires a consumption of about 1 mmol H2/g We can conclude that both, surface area and the presence of ionic oxygen species, are necessary for the catalytic performance of mayenite and an adequate combination of high surface area and high number of active species will result in a better activity of the mayenite for the TCE oxidation In this system the role of the O2 present in the reaction feed is the regeneration of the active oxygen species (O2−, O−, O2−) of the catalyst surface that in turn, can react and oxidize TCE32. More harmful by-products, such as Cl2 and PCE, were detected only in traces at the different temperatures investigated
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
