Sulfur-tolerant BaO/ZrO2/TiO2/Al2O3 quaternary mixed oxides for deNOX catalysis

Abstract

Advanced quaternary mixed oxide materials in the form of BaO/Al₂O₃/ZrO₂/TiO₂ functionalized with Pt active sites (i.e. Pt/BaO/AZT) were synthesized and structurally characterized via XRD and BET in comparison to a conventional Pt/20BaO/Al benchmark NSR/LNT catalyst. The interactions of these catalysts' surfaces with SO_x and NO_x gases were monitored via in situ FTIR and TPD. There exists a delicate trade-off between NO_x storage capacity (NSC) and sulfur uptake/poisoning which is strongly governed by the BaO loading/dispersion as well as the surface structure and acidity of the support material. Flow reactor measurements performed under realistic catalytic conditions show the high NO_x activity for the Pt/20BaO/AZT catalyst at 573 K. After sulfur poisoning and subsequent regeneration at 773 and 973 K, Pt/20BaO/AZT surpassed the NO_x catalytic performance at 573 K of all other investigated materials including the conventional Pt/20BaO/Al benchmark catalyst.