Spectroscopic investigation of sulfur-resistant Pt/K2O/ZrO2/TiO2/Al2O3 NSR/LNT catalysts

• AZT-based materials are functionalized with K2O to obtain novel NSR catalysts.
• Pt/5.4K/AZT has comparable NSC to that of and Pt/Ba/Al at 573 K.
• Pt/5.4K/AZT has superior SOx reduction/regeneration character than Pt/20Ba/Al.
• Increase in K2O loading leads to the formation of bulk-like sulfates.
• The delicate balance between NSC and S-tolerance is governed by K2O loading.

An alternative ternary support oxide material and its K2O and Pt functionalized counterparts in the form of Pt/K2O/Al2O3/ZrO2/TiO2 with different K2O loadings were synthesized. Structural and morphological properties of the catalysts were characterized via XRD and BET techniques in comparison to a conventional Pt/20Ba/Al benchmark NSR/LNT catalyst. Comprehensive in-situ FTIR and TPD analysis revealed that increasing the K2O loading in the Pt/K2O/AZT system leads to an increase in NOx Storage Capacity (NSC) at the expense of the formation of bulk-like sulfates requiring higher temperature for complete sulfur elimination with H2(g). Observed delicate trade-off between NSC and sulfur poisoning tendencies of the currently investigated family of AZT-based NSR/LNT catalysts implies that Pt/5.4K2O/AZT is a promising catalyst revealing comparable NSC within the temperature range of 473–673 K to that of the conventional Pt/20Ba/Al benchmark catalyst, while exhibiting superior sulfur tolerance and regeneration characteristics.

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