New Insight into Inhibition effect of SO2 and H2O on deNOx Performance of FeTi Catalyst Prepared by a CTAB-Assisted Process

Abstract

FeTi catalysts prepared by a CTAB-assisted process exhibited good resistance to H 2 O and SO 2 when tested in the selective catalytic reduction (SCR) at low temperatures. The physicochemical properties of the catalysts and the NO reaction behaviour under the influence of H 2 O and SO 2 were extensively characterized using BET, TEM, TPD-MASS, TPSR and in-situ DRIFTS. It was found that catalyst deactivation in the early stage of H 2 O and SO 2 introduction was mainly caused by pore plugging, resulting from the ammonium-sulfate salts deposition, while the active phase sulfation and competitive adsorption became the dominant catalyst-inhibiting factors in the later stage. SO 2 not only greatly inhibited NO adsorption on the catalyst surface, hindering the reaction through the Langmuir-Hinshelwood path, but also inhibited the reaction between adsorbed NH 3 and NO (Eley-Rideal path). Moreover, H 2 O promoted the transformation of NH 4 HSO 4 to (NH 4 ) 2 SO 4 , suggesting the "combined inhibition" of SO 2 and H 2 O, which was also reflected by in-situ DRIFTS that a clear increase of NH 3 adsorbed sites and sulfate species could be detected, thus resulting in more serious deactivation.