Synthesis and characterization of Al2O3 and ZrO2–TiO2 nano-composite as a support for NO  storage–reduction catalyst

Imagawa, Haruo; Tanaka, Toŝhiyuki; Takahashi, Naoki; Matsunaga, Shigenori; Suda, Akihiko; Shinjoh, Hirofumi

doi:10.1016/j.jcat.2007.08.002

Cited by 45 publications

(30 citation statements)

References 13 publications

(21 reference statements)

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“…Takahashi et al [20] investigated the influence of the relative abundance of TiO 2 and ZrO 2 components and found that the NSR system that was comprised of 70 wt% ZrO 2 and 30 wt% TiO 2 exhibited the best sulfur tolerance. Imagawa et al [21,22] reported a detailed characterization study related to the Al 2 O 3 /ZrO 2 /TiO 2 ternary oxide system emphasizing the impact of Al 2 O 3 incorporation into the ZrO 2 /TiO 2 mixed oxide where it was indicated that nano-composite Al 2 O 3 /ZrO 2 /TiO 2 had a higher NO x storage capacity and a higher thermal resistance as compared to the physically mixed Al 2 O 3 and ZrO 2 /TiO 2 .…”

Section: Introductionmentioning

confidence: 99%

NOx storage and reduction pathways on zirconia and titania functionalized binary and ternary oxides as NOx storage and reduction (NSR) systems

2014

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a b s t r a c tBinary and ternary oxide materials, ZrO 2 /TiO 2 (ZT) and Al 2 O 3 /ZrO 2 /TiO 2 (AZT), as well as their Ptfunctionalized counterparts were synthesized and characterized via XRD, Raman spectroscopy, BET, in situ FTIR and TPD techniques. In the ZT system, a strong interaction between TiO 2 and ZrO 2 domains at high temperatures (>973 K) resulted in the formation of a low specific surface area (i.e. 26 m 2 /g at 973 K) ZT material containing a highly ordered crystalline ZrTiO 4 phase. Incorporation of Al 2 O 3 in the AZT structure renders the material highly resilient toward crystallization and ordering. Alumina acts as a diffusion barrier in the AZT structure, preventing the formation of ZrTiO 4 and leading to a high specific surface area (i.e. 264 m 2 /g at 973 K). NO x adsorption on the AZT system was found to be significantly greater than that of ZT, due to almost ten-fold greater SSA of the former surface. While Pt incorporation did not alter the type of the adsorbed nitrate species, it significantly boosted the NO x adsorption on both Pt/ZT and Pt/AZT systems. Thermal stability of nitrates was higher on the AZT compared to ZT, most likely due to the defective structure and the presence of coordinatively unsaturated sites on the former surface. Pt sites also facilitate the decomposition of nitrates in the absence of an external reducing agent by shifting the decomposition temperatures to lower values. Presence of Pt also enhances partial/complete NO x reduction in the absence of an external reducing agent and the formation of N 2 and N 2 O. In the presence of H 2 (g), reduction of surface nitrates was completed at 623 K on ZT, while this was achieved at 723 K for AZT. Nitrate reduction over Pt/ZT and Pt/AZT via H 2 (g) under mild conditions initially leads to conversion of bridging nitrates into monodentate nitrates/nitrites and the formation of surface OH and NH x functionalities. N 2 O(g) was also continuously generated during the reduction process as an intermediate/byproduct.

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Section: Introductionmentioning

confidence: 99%

NOx storage and reduction pathways on zirconia and titania functionalized binary and ternary oxides as NOx storage and reduction (NSR) systems

2014

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“…It was found that the mixture of TiO 2 and -Al 2 O 3 used as support could minimize the amount of SO x deposit on the catalysts . In similar line, a nano-composite containing Al 2 O 3 and ZrO 2 -TiO 2 (AZT) solid solution, which was used as support for Pt (1.23 wt.%) / Rh (0.06 wt.%) / Ba (18.8 wt.%) / K (5.8 wt.%) / AZT was synthesized (Imagawa et al, 2007;Imagawa et al, 2009). The amounts of NO x stored at 400 and 500C were similar to that obtained at 300C.…”

Section: Hydrotalcites and Their Derived Formmentioning

confidence: 99%

A short review about NOx storage-reduction catalysts based on metal oxides and hydrotalcite-type anionic clays

Jabłońska¹,

Palomares

Węgrzyn³

et al. 2013

Acta Geodynamica Et Geomaterialia

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The increasing problem of atmospheric pollution by NO x has resulted in stricter regulations on their emissions. NO x storage/reduction (NSR) is considered as efficient catalytic technology to abate lean-burn NO x . A wide variety of catalysts have been extensively examined for this purpose. The use of metal oxides, hydrotalcites and their derivatives as NO x storage/reduction catalysts has been reviewed. Suitable combination particularly the catalytic redox component and the storage component can lead to improved activity in NO x decomposition and capturing under the lean-rich conditions. ARTICLE INFO

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“…Although nano-composite Al 2 O 3 -TiO 2 -ZrO 2 has ever been synthesized by Imagawa et al [16], the NO x storage routes of the LNT catalyst with K supported on this kind of ternary oxides support have not been investigated before. Recently we have reported the NO x storage routes over Pt/K/TiO 2 -ZrO 2 using the binary oxides TiO 2 -ZrO 2 as a support [13].…”

Section: In Situ Drifts Of No and O 2 Co-adsorptionmentioning

confidence: 99%

“…However, after calcination at a high temperature of 800°C [12], it is found that TiO 2 -ZrO 2 binary oxides show low specific surface areas. Imagawa et al [16,17] found that the thermal aggregation of TiO 2 -ZrO 2 particles can be inhibited in the presence of Al 2 O 3 particles. They also indicated that the LNT catalyst using the ternary oxides synthesized by co-precipitation as a support shows larger NO x storage capacity than that using the physical mixture of Al 2 O 3 and TiO 2 -ZrO 2 binary oxides as a support.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2008

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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.

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Synthesis and characterization of Al2O3 and ZrO2–TiO2 nano-composite as a support for NO storage–reduction catalyst

Cited by 45 publications

References 13 publications

NOx storage and reduction pathways on zirconia and titania functionalized binary and ternary oxides as NOx storage and reduction (NSR) systems

NOx storage and reduction pathways on zirconia and titania functionalized binary and ternary oxides as NOx storage and reduction (NSR) systems

A short review about NOx storage-reduction catalysts based on metal oxides and hydrotalcite-type anionic clays

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

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