FTIR study of the selective catalytic reduction of NO2 with ammonia on nanocrystalline NaY and CuY

Elzey, Sherrie; Mubayi, Anamika; Larsen, Sarah C.; Grassian, Vicki H.

doi:10.1016/j.molcata.2007.12.032

Cited by 49 publications

(40 citation statements)

References 32 publications

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“…In the 3500-3000 cm −1 spectral range (spectra not shown), IR spectra were distinguished by bands at 3356, 3273, 3220 and 3189 cm −1 assigned to N-H stretching vibration modes [1,[35][36][37]. More precisely, the band at 3189 cm −1 is assigned to Cu + -NH 3 [38,39].…”

Section: Nh 3 Adsorptionmentioning

confidence: 98%

Influence of the Sodium Impregnation Solvent on the Deactivation of Cu/FER-Exchanged Zeolites Dedicated to the SCR of NOx with NH3

et al. 2017

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Abstract:The effect of the sodium addition mode was investigated on model Cu/FER selective catalytic reduction (SCR) catalysts with two copper loadings (2.8 wt. % and 6.1 wt. %) in order to compare samples with or without over-exchanged copper. Na was added by wet-impregnation using two solvents: water or ethanol. Catalysts were evaluated in Standard and Fast-SCR conditions, as well as in NO and NH 3 oxidation. They were characterized by H 2 -TPR, NO and NH 3 adsorption monitored by FT-IR. As expected, whatever the copper loading, ammonia adsorption capacity was decreased by Na additions. Interestingly, characterizations also showed that Na impregnation in water favors the migration of the Cu-exchanged species, leading to the formation of CuO extra-framework compounds. Consequently, for both copper loadings, Na impregnation in water led to a stronger catalyst deactivation than impregnation in ethanol. Finally, the NO x conversion at low temperature (250 • C) appeared mainly affected by the loss in NH 3 adsorption capacity whereas the deNO x deactivation at high temperature (500 • C) was rather governed by the decrease in the exchanged copper ratio, which also induced a partial inhibition of NO and NH 3 oxidation behaviors.

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Section: Nh 3 Adsorptionmentioning

confidence: 98%

Influence of the Sodium Impregnation Solvent on the Deactivation of Cu/FER-Exchanged Zeolites Dedicated to the SCR of NOx with NH3

et al. 2017

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“…Four standard calibration solutions with known silicon (aluminum, sodium, and copper) concentrations were prepared. 79 A working curve was then generated, from which the silicon, aluminum, sodium and barium concentrations in various zeolite sample solutions were obtained. 79…”

Section: Inductively Coupled Plasma Optical Emission Spectroscopymentioning

confidence: 99%

Carbon dioxide adsorption on nanomaterials

Galhotra¹

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In this study, CO 2 adsorption in the presence and absence of co-adsorbed H 2 O was investigated on different nanomaterials including nanocrystalline NaY zeolite (nano NaY), ZnO, MgO and γ-Al 2 O 3 nanoparticles as well as mixed phase aluminum nanowhiskers. In the case of nano NaY, FTIR spectra show that a majority of CO 2 adsorbs in the pores of these zeolites in a linear complex with the exchangeable cation. Most interesting is the formation of carbonate and bicarbonate on the external surface of nano NaY zeolites, suggesting unique sites for CO 2 adsorption on the surface of these small nanomaterials. Adsorption of 18 O-labeled carbon dioxide and theoretical quantum chemical calculations confirms the assignment of these different species. For aluminum oxyhydroxide nanowhiskers and gamma alumina in the absence of co-adsorbed water, CO 2 reacts with surface hydroxyl groups to yield adsorbed bicarbonate as well as some carbonate. C 18 O 2 adsorption confirms these assignments. In the case of nanoparticulate ZnO, CO 2 adsorption under dry conditions results in formation of carbonate, bicarbonates as well as carboxylates. However, in the presence of co-adsorbed water, only carbonate species is formed. 18 O-labeled carbon dioxide adsorption and theoretical quantum chemical calculations confirm the vibrational assignment for these different species. Mixed isotope studies with H 2 16 O + C 18 O 2 and H 2 18 O + C 16 O 2 suggest that there is extensive exchange between oxygen in adsorbed water and oxygen atoms in gas-phase carbon dioxide. CO 2 adsorption on MgO surfaces, under dry conditions results in formation of carbonate and bicarbonates. Implications for the use of these nanomaterials in carbon dioxide uptake and storage are discussed. vi

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“…Studies using nanosized zeolite crystals for esterification of cyclohexanol with acetic acid showed that the catalytic activity depends directly on the external surface area and improved porosity present in nanocrystalline ZSM-5 zeolite [15]. Particle size reduction to nanometer actually increases the ratio of external to internal atoms; therefore, zeolite nanoparticles possess large external surface area and higher activity [16]. Furthermore, pervaporation process has gained widespread acceptance in the chemical industry as an effective process for separation 2 Journal of Nanomaterials of azeotropic mixtures; however, the crystallinity of zeolites that provides these attractive features imposes challenges on film fabrication, for example, to minimize the effect of grain boundary defects on permeation properties and to avoid stress-induced crack formation [17].…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Zeolite Nanomolecular Sieves of Different Si/Al Ratios

Sharma

Han

Cho

2015

Journal of Nanomaterials

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Nanosized zeolite molecular sieves of different Si/Al ratios have been prepared using microwave hydrothermal reactor (MHR) for their greater application in separation and catalytic science. The as-synthesized molecular sieves belong to four different type zeolite families: MFI (infinite and high silica), FAU (moderate silica), LTA (low silica and high alumina), and AFI (alumina rich and silicafree). The phase purity of molecular sieves has been assessed by X-ray diffraction (XRD) analysis and morphological evaluation done by electron microscopy. Broad XRD peaks reveal that each zeolite molecular sieve sample is composed of nanocrystallites. Scanning electron microscopic images feature the notion that the incorporation of aluminum to MFI zeolite synthesis results in morphological change. The crystals of pure silica MFI zeolite (silicalite-1) have hexagon lump/disk-like shape, whereas MFI zeolite particles with Si/Al molar ratios 250 and 100 have distorted hexagonal lump/disk and pseudo spherical shapes, respectively. Furthermore, phase pure zeolite nanocrystals of octahedron (FAU), cubic (LTA), and rod (AFI) shape have been synthesized. The average sizes of MFI, FAU, LTA, and AFI zeolite crystals are 250, 150, 50, and 3000 nm, respectively. Although the length of AFI zeolite rods is in micron scale, the thickness and width are of a few nanometers.

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FTIR study of the selective catalytic reduction of NO2 with ammonia on nanocrystalline NaY and CuY

Cited by 49 publications

References 32 publications

Influence of the Sodium Impregnation Solvent on the Deactivation of Cu/FER-Exchanged Zeolites Dedicated to the SCR of NOx with NH3

Influence of the Sodium Impregnation Solvent on the Deactivation of Cu/FER-Exchanged Zeolites Dedicated to the SCR of NOx with NH3

Carbon dioxide adsorption on nanomaterials

Synthesis of Zeolite Nanomolecular Sieves of Different Si/Al Ratios

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