Identification of Neutral and Charged NxOySurface Species by IR Spectroscopy

Hadjiivanov, Konstantin

doi:10.1081/cr-100100260

Cited by 1,479 publications

(1,430 citation statements)

References 237 publications

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“…It is evident that bridging nitrates are readily visible on the LaMnO 3 perovskite, while these species are less pronounced on the LaCoO 3 surface. Another type of adsorbed nitrate, revealing vibrational features at 1530 and 1269 cm −1 can be assigned to monodentate nitrates [37]. Two characteristic vibrational modes of bidentate nitrates are also observed on the surface which are located at 1568 and 1246 cm −1 [35,36].…”

Section: Resultsmentioning

confidence: 88%

“…6a (and similar bands in Fig. 6b) can be assigned to N=O , N-O and ␦ ONO vibrations of monodentate surface nitrites (-O-N=O), respectively [37][38][39][40]. The weak absorption bands at 1090 and 1194 cm −1 which are apparent only at the initial stage of NO 2 (g) exposure and disappear at higher exposures can be assigned to bridging and/or chelating nitrites [11].…”

Section: Resultsmentioning

confidence: 96%

“…Fig. 6c) samples at 323 K. FTIR spectra yield a convoluted set of bands corresponding to various types of nitrates and nitrites with different surface adsorption geometries [34][35][36][37][38][39][40]. Vibrational features appearing at 1649 and 1009 cm −1 are assigned to asymmetric and symmetric stretching modes of bridging nitrate species on the perovskite surface, respectively [34].…”

Section: Resultsmentioning

confidence: 99%

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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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Doğaç

Vovk

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: Resultsmentioning

confidence: 88%

Section: Resultsmentioning

confidence: 96%

Section: Resultsmentioning

confidence: 99%

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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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Doğaç

Vovk

et al. 2014

Applied Catalysis B: Environmental

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“…The bands at 1630 and 1320 cm À1 are assigned to the bridging nitrates at Ru-TiO 2 interface [32]. The band at 1440 cm À1 is assigned to mono-nitrite [33] while the band at 1350 cm À1 is assigned to chelating nitrites [34]. The intensity of IR bands corresponding to nitrates/nitrites increased with increasing adsorption time, and new IR band corresponding to mono-dentate nitrate [35] at 1500 cm À1 appeared after 9 min of NO adsorption.…”

Section: Effects Of Catalysts Pretreatment Conditions On No Oxidationmentioning

confidence: 96%

“…At 150 8C, strong bands at 1630, 1600, 1500 and 1305 cm À1 as well as weak bands at 1875 and 1370 cm À1 have been observed. The bands at 1630 and 1600 cm À1 are assigned to different kinds of bridging nitrates [32,33], while the band at 1305 cm À1 is assigned to chelating nitrates [34]. The band at 1500 cm À1 is assigned to mono-dentate nitrate and the band at 1370 cm À1 is assigned to free nitrates [37].…”

Section: Effects Of Catalysts Pretreatment Conditions On No Oxidationmentioning

confidence: 99%

Oxidation of nitric oxide to nitrogen dioxide over Ru catalysts

Cheng

et al. 2009

Applied Catalysis B: Environmental

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Vibrational Spectroscopy in the Study of Oxide (Excluding Zeolites) and Sulfide Catalysts

Payen

Grimblot

Lavalley³

et al. 2001

Handbook of Vibrational Spectroscopy

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The sections in this article are Introduction Infrared Spectroscopy IR Characterization of Surface Properties of Metal Oxides Information Deriving from the Activated Oxide Spectra Lattice Vibrations Surface Oxide Sites Identification of Main Impurities in Metal Oxides Electronic Transitions Hydroxyl Groups Information Deriving from Probe Adsorption Acidity Basicity Cationic and Redox Sites: Use of Methanol as Probe for Local Arrangement and Oxidation State Determination of Surface Cationic Sites IR Characterization of Oxide and Sulfide Supported Catalysts Information Deriving from the Spectrum of the Activated Catalyst Information Deriving from Probe Molecule Adsorption CUS Characterization of the Sulfided Phase B rønsted Acid Site Characterization of the Sulfided Phase Site Transformation in the Presence of H 2 Surface Characterization and Catalysis Conclusion R aman Spectroscopy General Considerations Bulk Oxide Catalysts Supports Supported Oxides Nature of the Supported Oxide Chemical Processes Involved During Catalyst Synthesis Adsorption of Probe Molecules Surface B rønsted and Lewis Acid Sites Adsorption of Molecules Acting as Reagents Active Phase: Genesis and Characterization Genesis of the Hydrodesulfurization Active Phase Sulfided Catalyst Catalyst Reactivity Conclusion Concluding Remarks and Outlook

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Identification of Neutral and Charged N_xO_ySurface Species by IR Spectroscopy

Cited by 1,479 publications

References 237 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

Oxidation of nitric oxide to nitrogen dioxide over Ru catalysts

Vibrational Spectroscopy in the Study of Oxide (Excluding Zeolites) and Sulfide Catalysts

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