VOX/TiO2 catalysts with different vanadium loading were prepared in order to study the influence of vanadium
species on the effect of water in the simultaneous NO reduction through NH3-SCR and o-DCB oxidation reactions.
The presence of isolated, polymeric and crystalline species and their redox and acid properties were evaluated by
N2-Adsorption, XRD, Raman, H2-TPR, XPS and NH3-TPD. Water has a bimodal and reversible effect in both NO
reduction and o-DCB oxidation depending on vanadium species and temperature. In SCR, water has a detrimental
effect at low temperature due to competitive adsorption with NO and NH3, while at high temperature it promotes
an increase of NO conversion associated to the suppression of side-reactions, which increase the selectivity towards N2. In o-DCB oxidation, the effect of water is the sum of two contributions: one positive, related to the
removal of surface adsorbed detrimental species; and one negative, associated to the competitive adsorption with
o-DCB. Thus, at high temperature water acts as inhibitor, while at low temperature water has a promotional
effect in the highly dispersed vanadium catalysts due to their tendency to suffer deactivation, mainly by
carbonaceous materials. The presence of water also favors total oxidation and decreases the formation of
chlorinated by products.MINECO/FEDER (CTQ2015-64616-P), MINECO/FEDER (BES-2016-077849), IT657-13, IT1297- 19, INF12/37, UFI 11/39, PID2019-107503RB-I00, MCIN/AEI/10.13039/50110001103
