Removal of toluene by sequential adsorption-plasma oxidation: Mixed support and catalyst deactivation

A sequential adsorption-plasma oxidation system was used to remove toluene from simulated dry air using gamma-Al2O3, HZSM-5, a mixture of the two materials or their supported Mn-Ag catalyst as adsorbents under atmospheric pressure and room temperature. After 120 min of plasma oxidation, gamma-Al2O3 had a better carbon balance (similar to 75%) than HZSM-5, but the CO2 yield of gamma-Al2O3 was only similar to 50%; and there was some desorption of toluene when gamma-Al2O3 was used. When a mixture of HZSM-5 and gamma-Al2O3 with a mass ratio of 1/2 was used, the carbon balance was up to 90% and 82% of this was CO2. The adsorption performance and electric discharge characteristics of the mixed supports were tested in order to rationalize this high COx yield. After seven cycles of sequential adsorption-plasma oxidation, support and Mn-Ag catalyst deactivation occurred. The support and catalyst were characterized before and after deactivation by SEM, a BET method, XRD, XPS and GC-MS in order to probe the mechanism of their deactivation. 97.6% of the deactivated supports and 76% of the deactivated catalysts could be recovered by O-2 temperature-programmed oxidation. (C) 2017 Elsevier B.V. All rights reserved.