The Effect of Al2O3 Doping into TiO2–ZrO2 on the Storage and Sulfur-resistance Performance of the NO x Trap Catalyst Pt/K/TiO2–ZrO2

Abstract

A series of lean-burn NO x trap (LNT) catalyst Pt/K/Al 2 O 3 -TiO 2 -ZrO 2 were prepared by sequential impregnation with the support synthesized by coprecipitation. The effect of Al 2 O 3 doping into TiO 2 -ZrO 2 on the storage and sulfur-resistance performance of the catalyst Pt/K/TiO 2 -ZrO 2 was investigated carefully. In situ DRIFTS spectra show that the NO x is mainly stored as nitrate at the optimal temperature of *350°C. The NO x storage capacity (NSC) of Pt/K/TiO 2 -ZrO 2 was greatly improved by Al 2 O 3 doping due to the remarkably increased specific surface area and the decreased Ti content. The results of sulfation and regeneration by H 2 -TPR reveal that the sulfur on Al 2 O 3 -TiO 2 -ZrO 2 supported catalysts is easier to be removed, making them possess much better sulfur-resisting ability than TiO 2 -ZrO 2 or Al 2 O 3 supported ones. The NSC recovery efficiency of Al 2 O 3 -TiO 2 -ZrO 2 supported catalysts can reach as high as 81-96% while only 30.4 and 62.5% were achieved for the catalysts supported on pure Al 2 O 3 and TiO 2 -ZrO 2 , respectively. The doped catalyst with the Al/(Ti ? Zr) atomic ratio of 3:1 always shows the highest NSC before or after sulfation-regeneration.

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

“…In addition, Zou et al investigated the influence of the mass ratio of Al 2 O 3 : ZrO 2 -TiO 2 on the performance of the Pt/K/AZT LNT catalyst and reported that a mass ratio of 1 : 1 revealed the best performance after sulfur poisoning. 32 In the current study, we focus on the SO x adsorption and SO x reduction/regeneration/release properties of ternary (Al 2 O 3 /ZrO 2 /TiO 2 , AZT) and quaternary (BaO/Al 2 O 3 /ZrO 2 /TiO 2 , BaO/AZT) mixed oxide systems functionalized with redox active Pt sites in comparison to a benchmark NSR/LNT catalyst (i.e. Pt/BaO/Al 2 O 3 ) via in situ Fourier Transform Infrared Spectroscopy (in situ FTIR), Temperature Programmed Desorption (TPD), XRD and BET surface area analysis techniques.…”

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

“…In recent studies, ZrO 2 /TiO 2 , TiO 2 /Al 2 O 3 and Al 2 O 3 /ZrO 2 /TiO 2 -supported NSR/LNT catalysts can reveal superior sulfur regeneration and NO x recovery performances as compared to that of ␥-Al 2 O 3 -based systems (i.e. Pt/BaO/Al 2 O 3 vs. Pt/K 2 O/Al 2 O 3 ) [26,27]. Takashi et al reported that a ZrO 2 :TiO 2 support material with a mass ratio of 70:30 (which also revealed the highest SSA among the investigated materials therein) exhibited the best performance in terms of sulfur resistance, thermal durability and NO x abatement [28].…”

“…Their studies which also included Pt/Rh/Ba/K/AZT catalyst with nano-composite ternary oxide Al 2 O 3 /ZrO 2 /TiO 2support showed excellent NO x storage capacity (NSC) compared to that of ␥-Al 2 O 3 /ZrO 2 /TiO 2 -support, where ␥-Al 2 O 3 was physically mixed with ZrO 2 /TiO 2 [29,30]. In addition, Zou et al [27] performed a detailed analysis on the effect of Al 2 O 3 doping into the ZrO 2 /TiO 2 matrix, suggesting that the Al:(Ti + Zr) atomic ratio of 3:1 exhibited the highest NSC for fresh and sulfur-regenerated catalyst. In a more recent work, Zou et al studied the effect of K loading on the NSC and sulfur regeneration performance of Pt/K/Al 2 O 3 /ZrO 2 /TiO 2 catalyst under realistic flow conditions [31].…”

Perovskite-Based Lean-Burn NO x Trap Catalysts Without Using Platinum Group Metals: K/LaCoO3/Ce1−x Zr x O2

“…If some Ce ions in CeO 2 are replaced by Zr ions forming CeO 2 -ZrO 2 solid solution, much higher thermal stability and better redox property could be achieved [16], which makes the CeO 2 -ZrO 2 solid solution more potential as supports. About the storage component in LNT catalysts, K has received more attention in the last several years, due to its excellent NO x storage performance and higher sulfur resistance as compared Ba [17][18][19].…”