Studies of the activation process over Pd perovskite-type oxides used for catalytic oxidation of toluene

Giraudon, Jean‐Marc; Elhachimi, Amal; Wyrwalski, F.; Siffert, Stéphane; Aboukaı̈s, Antoine; Lamonier, Jean‐François; Leclercq, G.

doi:10.1016/j.apcatb.2007.04.005

Cited by 129 publications

(65 citation statements)

References 29 publications

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“…Another Raman feature at 644 cm −1 can be attributed to a Mn-O-Mn stretching mode ( Mn-O-Mn ) in the perovskite structure in accordance with Li et al [26] who reported a similar peak at 654 cm −1 for Mn 3 O 4 , as well as Ammundsen et al [27] who also reported a Raman signal at 647 cm −1 for MnO 2 . Furthermore, this assignment is also consistent with the previously published Raman data on Pd/LaMnO 3 [28] which revealed a major signal at 653 cm −1 . There is also another weak feature located at ca.…”

Section: Resultssupporting

confidence: 81%

Palladium doped perovskite-based NO oxidation catalysts: The role of Pd and B-sites for NOx adsorption behavior via in-situ spectroscopy

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et al. 2014

Applied Catalysis B: Environmental

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a b s t r a c tPerovskite-based materials (LaMnO 3 , Pd/LaMnO 3 , LaCoO 3 and Pd/LaCoO 3 ) were synthesized, characterized (via BET, XRD, Raman spectroscopy, XPS and TEM) and their NO x (x = 1,2) adsorption characteristics were investigated (via in-situ FTIR and TPD) as a function of the nature of the B-site cation (i.e. Mn vs Co), Pd/PdO incorporation and H 2 -pretreatment. NO x adsorption on of LaMnO 3 was found to be significantly higher than LaCoO 3 , in line with the higher SSA of LaMnO 3 . Incorporation of PdO nanoparticles with an average diameter of ca. 4 nm did not have a significant effect on the amount of NO 2 adsorbed on fresh LaMnO 3 and LaCoO 3 . TPD experiments suggested that saturation of fresh LaMnO 3 , Pd/LaMnO 3 , LaCoO 3 and Pd/LaCoO 3 with NO 2 at 323 K resulted in the desorption of NO 2 , NO, N 2 O and N 2 (without O 2 ) below 700 K, while above 700 K, NO x desorption was predominantly in the form of NO + O 2 . Perovskite materials were found to be capable of activating N-O linkages typically at ca. 550 K (even in the absence of an external reducing agent) forming N 2 and N 2 O as direct NO x decomposition products. H 2 -pretreatment yielded a drastic boost in the NO oxidation and NO x adsorption of all samples, particularly for the Cobased systems. Presence of Pd further boosted the NO x uptake upon H 2 -pretreatment. Increase in the NO x adsorption of H 2 -pretreated LaCoO 3 and Pd/LaCoO 3 surfaces could be associated with the electronic changes (i.e. reduction of B-site cation), structural changes (surface reconstruction and SSA increase), reduction of the precious metal oxide (PdO) into metallic species (Pd), and the generation of oxygen defects on the perovskite. Mn-based systems were more resilient toward B-site reduction. Pd-addition suppressed the B-site reduction and preserved the ABO 3 perovskite structure.

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Section: Resultssupporting

confidence: 81%

Palladium doped perovskite-based NO oxidation catalysts: The role of Pd and B-sites for NOx adsorption behavior via in-situ spectroscopy

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et al. 2014

Applied Catalysis B: Environmental

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“…Easier but also higher extend of reduction of mixed oxides present in Mn 6 Al 2 HT(500) and Co 2 Mn 4 Al 2 HT(500) samples lead to an efficient catalyst for catalytic toluene removal. Studying the activation process over Pd perovskite-type oxides, Giraudon et al [39] have shown that, in the same test conditions, toluene is fully oxidized at 225, 250 and 280°C over respectively Pd(0.5 wt%)/LaFeO 3 , Pd(0.5 wt%)/LaCoO 3 and Pd(0.5 wt%)/LaNiO 3 catalysts. Since in our study a temperature of 250°C is needed to completely convert toluene into CO 2 and H 2 O over Co 2 Mn 4 Al 2 HT(500) and Mn 6 Al 2 HT(500) samples, we can stated that Co-Mn-Al nano-oxides synthesized by hydrotalcite route are very promising candidates for the substitution of noble metal based solids.…”

Section: Catalytic Activity Of Calcined Co-mn-almentioning

confidence: 97%

Catalytic Removal of Toluene in Air over Co–Mn–Al Nano-oxides Synthesized by Hydrotalcite Route

et al. 2007

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Co-Mn-Al hydrotalcite type solids were synthesized as precursors of catalysts for the total oxidation of toluene in air. For the as-prepared solids, XRD measurements indicate the coexistence of hydrotalcite and MnCO 3 phases. When calcination is performed at 500°C, different mixed oxides are found as a function of Co:Mn molar ratio and preparation method, and very high specific surface areas were obtained for the Co-Mn solids. The comparison of catalytic activities in the presence of calcined hydrotalcites with those in the presence of calcined hydroxides evidences the superiority of the first oxides due to their higher reducibility. Co-Mn-Al nano-oxides synthesized using hydrotalcite type solids as precursors, are very promising candidates for the substitution of noble metal based solids.

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“…[14][15][16] Due to their unique thermal, mechanical and redox stability and catalytic performance, perovskites could serve as active support to reduce the noble metal loading. [17][18][19] Despite their sufficient catalytic efficiency, the weak hydrothermal resistance and small oxygen storage capacity (OSC) lead to depletion of catalytic activity directly aer rapid aging cycles. [20][21][22] In 2012, Wang et al proposed a new type of mixed-phase oxide catalyst for NO oxidation based on Mn mullite ((Sm, Gd)Mn 2 O 5 ), which has exhibited favorable thermal and structural stability.…”

Section: Introductionmentioning

confidence: 99%

Highly dispersed Pd on macroporous SmMn₂O₅ mullite for low temperature oxidation of CO and C₃H₈

Zhu

Feng

et al. 2018

RSC Adv.

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The catalytic behavior of a palladium catalyst supported on macroporous SmMn 2 O 5 mullite (Pd/SMO-EG&M) for CO and C 3 H 8 oxidation was measured under lean-burn conditions. Different analytical techniques including XRD, Raman, BET, CO chemisorption, SEM, FTEM, XPS, TPD, TPR and CO + O 2 pulse were undertaken to evaluate its physical and chemical properties. It was concluded that the crystal structure, morphology and specific surface area (SSA) of SmMn 2 O 5 remained unchanged after Pd addition. The Pd/SMO-EG&M exhibited a low complete transformation temperature for CO (105 C) and C 3 H 8 (350 C) oxidation. Such remarkable oxidation activity was attributed to high Pd dispersion (38.4%), which improved the reducibility and mobility of oxygen species, as revealed by TPR and TPD measurements. The high activity of oxygen species for Pd/SMO-EG&M above 250 C accelerated the oxidation capacity as well. In a word, our study indicates that the macroporous Pd-mullite catalyst has potential applications in exhaust purification for gasoline vehicle.

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Studies of the activation process over Pd perovskite-type oxides used for catalytic oxidation of toluene

Cited by 129 publications

References 29 publications

Palladium doped perovskite-based NO oxidation catalysts: The role of Pd and B-sites for NOx adsorption behavior via in-situ spectroscopy

Palladium doped perovskite-based NO oxidation catalysts: The role of Pd and B-sites for NOx adsorption behavior via in-situ spectroscopy

Catalytic Removal of Toluene in Air over Co–Mn–Al Nano-oxides Synthesized by Hydrotalcite Route

Highly dispersed Pd on macroporous SmMn₂O₅ mullite for low temperature oxidation of CO and C₃H₈

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Studies of the activation process over Pd perovskite-type oxides used for catalytic oxidation of toluene

Cited by 129 publications

References 29 publications

Palladium doped perovskite-based NO oxidation catalysts: The role of Pd and B-sites for NOx adsorption behavior via in-situ spectroscopy

Palladium doped perovskite-based NO oxidation catalysts: The role of Pd and B-sites for NOx adsorption behavior via in-situ spectroscopy

Catalytic Removal of Toluene in Air over Co–Mn–Al Nano-oxides Synthesized by Hydrotalcite Route

Highly dispersed Pd on macroporous SmMn2O5 mullite for low temperature oxidation of CO and C3H8

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Highly dispersed Pd on macroporous SmMn₂O₅ mullite for low temperature oxidation of CO and C₃H₈