The effect of deactivation of H‐zeolites on product selectivity in the oxidation of chlorinated VOCs (trichloroethylene)

Abstract BACKGROUND The literature on the activity of diverse catalytic formulations for the oxidation of chlorinated volatile organic compounds is very large. Catalyst stability or durability has been investigated to a lesser extent, and particularly the effect of deactivation on selectivity, although it is a key factor for commercial scale applicability. RESULTS H‐zeolites suffered from rapid deactivation to some lower residual activity in the oxidation of trichloroethylene ( TCE ). The catalyst deactivation led to a decrease of selectivity to HCl and CO 2 , but to an increased selectivity for tetrachloroethylene ( PER ) and CCl 4 . By co‐feeding water vapour, deactivation was avoided and the selectivity to PER and CCl 4 dropped near to zero. CONCLUSIONS These effects were due to the loss of hydroxyl groups, which were partially chlorinated while TCE was adsorbed and decomposed. The selectivity data of PER and CCl 4 with time on stream ( TOS ) did not allow the conclusion that the formation of PER and CCl 4 took place by chlorination of TCE through HCl (g) or Cl 2 (g), as was previously suggested by some authors in the literature. It was concluded that formation of PER and CCl 4 takes place through the chlorination of TCE by chlorine species previously adsorbed on the surface of the zeolite. © 2014 Society of Chemical Industry