Low-temperature catalytic reduction of NO by NH3 over vanadia-based nanoparticles prepared by flame-assisted spray pyrolysis: Influence of various supports

Boningari, Thirupathi; Koirala, Rajesh; Smirniotis, Panagiotis G.

doi:10.1016/j.apcatb.2013.04.033

Cited by 105 publications

(55 citation statements)

References 49 publications

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“…The bridging V O-support bond appears to be involved in the rate-determining step. This fact explains why the support has a determinant effect on the SCR reaction, being TiO 2 the most active support due to high interaction between V and Ti [17,35]. The same phenomenon occurs in the o-DCB oxidation [7,31] and this fact explains the competition, reported in Fig.…”

Section: Vo X Species Activity In the Simultaneous Removal Of O-dcb Asupporting

confidence: 51%

“…31 nm for the 8V/TiO 2 catalyst. The crystalline particle size was also calculated by the equation d BET = 6/( × S BET ), where is the material density (3.8 g cm −3 for pure TiO 2 ) [17] and S BET is the observed surface area (Table 1). Results are in the 22-27 nm range which correlate well with those obtained through XRD analysis (Table 1).…”

Section: Analysis Of Catalyst Composition and Textural Propertiesmentioning

confidence: 99%

“…Conversely, other publications [12,15] report the superior activity of polymeric species, when compared with isolated ones, concluding that V O V bonds present on polymeric and crystalline VO x species are the most active. In addition, it is also claimed that high amount of V +4 may improve the catalyst activity, indicating that further investigation is necessary [16,17].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Role of surface vanadium oxide coverage support on titania for the simultaneous removal of o-dichlorobenzene and NOx from waste incinerator flue gas

et al. 2015

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Section: Vo X Species Activity In the Simultaneous Removal Of O-dcb Asupporting

confidence: 51%

Section: Analysis Of Catalyst Composition and Textural Propertiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Role of surface vanadium oxide coverage support on titania for the simultaneous removal of o-dichlorobenzene and NOx from waste incinerator flue gas

et al. 2015

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“…Flame spray synthesis (FSS) was chosen for material synthesis because it affords nano-sized catalysts in a well controllable one-step process. [24][25][26][27][28][29] FSS allows obtaining unique material compositions and thus, particle properties as a result of the high flame temperature and the fast quenching rate. The one-step synthesis approach ensures close interaction of the components already at the synthesis level, which may not be identical to the result obtained with conventional methods.…”

Section: Introductionmentioning

confidence: 99%

Flame-Made WO₃/CeO_x-TiO₂ Catalysts for Selective Catalytic Reduction of NO_x by NH₃

et al. 2015

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Materials based on combination of tungsten-cerium-titanium are potentially durable catalysts for selective catalytic NO x reduction using NH 3 (NH 3 -SCR). Flame spray synthesis is used here to produce WO 3 /CeO x -TiO 2 nanoparticles, which are characterized with respect to their phase composition, morphology and acidic properties and are evaluated for deNO x by NH 3 -SCR. HR-TEM and XRD revealed that flame-made WO 3 /CeO x -TiO 2 consists of mainly rutile TiO 2 , brannerite CeTi 2 O 6 , cubic CeO 2 and a minor fraction of anatase TiO 2 . These phases coexist with a large portion of amorphous mixed Ce-Ti phase. The lack of crystallinity and the presence of brannerite together with the evident high fraction of Ce 3+ are taken as evidence that cerium is also present as a dopant in TiO 2 and is well dispersed on the surface of the nano-particles. Clusters of amorphous WO 3 homogeneously cover all particles as observed by STEM. Such morphology and phase composition guarantee short range Ce-O-Ti and Ce-O-W interactions and thus the high surface concentration of Ce 3+ . The presence of the WO 3 layer and the close Ce-O-W interaction further increase the Ce 3+ content compared to binary Ce-Ti materials as shown by XPS and XANES. The acidity of the materials and the nature of the acid sites were determined by NH 3 temperature programmed desorption (NH 3 -TPD) and DRIFT spectroscopy, respectively. TiO 2 possesses mainly strong Lewis acidity; addition of cerium, especially the presence of surface Ce 3+ in close contact with titanium and tungsten, inducesBrønsted acid sites that are considerably increased by the amorphous WO 3 clusters. As a result of this peculiar element arrangement and phase composition, 10 wt% WO 3 /10 mol% CeO x -90 mol% TiO 2 exhibits the highest deNO x efficiency, which matches that of a V 2 O 5 -WO 3 /TiO 2 catalyst. Preliminary activity data indicate that the flame-made catalyst demonstrates much higher performance after thermal and hydrothermal aging at 700°C than the V-based analogue despite the presence of the rutile phase. Ce 3+ remains the dominating surface cerium species after both aging treatments thus confirming its crucial role in NH 3 -SCR by Ce-W-Ti based catalysts.

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“…Several catalysts supported on various metal oxides such as Al 2 O 3 , SiO 2 , TiO 2 , CeO 2 and ZrO 2 are industrially important active catalysts. [9][10][11][12][13] Some of these catalysts have been briefly studied for the selective catalytic reduction (SCR) of nitrogen oxides. 10,[14][15][16][17] Among all the SCR catalysts, titania in the form of anatase phase is most widely used for the SCR reaction, although alumina and to a lesser extent silica are also used.…”

Section: Introductionmentioning

confidence: 99%

Influence of SiO₂ on M/TiO₂ (M = Cu, Mn, and Ce) Formulations for Low-Temperature Selective Catalytic Reduction of NO_x with NH₃: Surface Properties and Key Components in Relation to the Activity of NO_x Reduction

Boningari

Pappas

Ettireddy

et al. 2015

Ind. Eng. Chem. Res.

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A series of M/TiO 2 and M/TiO 2 -SiO 2 (with M = Mn, Cu and Ce) catalysts were prepared by adopting a wetimpregnation method and investigated for the selective catalytic reduction (SCR) of NO x in the temperature range of 100-500 o C with excess (10 vol.%) oxygen in the feed at industrially relevant conditions. Our XRD results suggest that the growth of crystalline TiO 2 phase is strongly inhibited due to the SiO 2 migration into the TiO 2 lattice. The increase of SiO 2 molar content in TiO 2 -SiO 2 support led to the decrease in anatase phase of titania peak intensity of XRD spectrum and also exhibiting a lower crystallinity of TiO 2 with no phase transition of anatase to rutile. Our XPS depth profile analysis illustrate that the surface atomic ratio of Cu 1+ / Cu 2+ greatly enhanced with increase in TiO 2 content in the TiO 2 -SiO 2 support, and these results are consistent with the H 2 -TPR results where the additional reduction peak evolved at 200 o C for copper loaded titania-rich (Cu/TiO 2 ) catalyst. The high activity of Cu-based TiO 2 formulations has been assigned to the enhancement in the formation of Cu 1+ active sites, existence of surface Cu 2+ , Cu 1+ species and the increment of reduction potentials of surface copper species. The Ce 3+ / Ce 4+ and Ce 3+ /Ce n+ atomic ratio (1.14 and 0.53, respectively) in Ce/TiO 2 catalyst calculated from deconvoluted XPS spectra are much higher than that of Ce/TiO 2 -SiO 2 (1:1) and Ce/TiO 2 -SiO 2 (3:1). The existence of higher Ce 3+ surface species over CeO 2 /TiO 2 illustrates the increment of surface oxygen vacancies and thus facilitates for the adsorption of oxygen species or activates reactants in the SCR reaction. The relative atomic percentage value of Mn 4+ /Mn 3+ characterized by deconvoluted XPS was significantly high (Mn 4+ /Mn 3+ = 1.98) for the Mn/TiO 2 compared to Mn/TiO 2 -SiO 2 catalysts (Mn 4+ /Mn 3+ = 1.23, 1.75). When ceria was supported on pure TiO 2 , the low-temperature reduction peak was broad and less defined, and the reducibility in the low temperature range was much less pronounced. On the other hand, the addition of ceria to titania with strong reciprocal interaction is generally perceived as a shift in the bulk reduction temperature to lower values, to about 500-650 °C. As bigger Ce 4+ ions enter the lattice structure to proxy the Ti 4+ ions with smaller ionic radii (2.48 and 2.15 Å, respectively), the lattice could become highly strained. The NO x conversions and the apparent kinetic constant of the catalyst k ac , over the Cu, Mn, Ce-loaded on different supports TiO 2 and TiO 2 -SiO 2 (3:1 and 1:1) catalysts measured under steady-state conditions results demonstrated higher activity of the Ti-rich materials.

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Low-temperature catalytic reduction of NO by NH3 over vanadia-based nanoparticles prepared by flame-assisted spray pyrolysis: Influence of various supports

Cited by 105 publications

References 49 publications

Role of surface vanadium oxide coverage support on titania for the simultaneous removal of o-dichlorobenzene and NOx from waste incinerator flue gas

Role of surface vanadium oxide coverage support on titania for the simultaneous removal of o-dichlorobenzene and NOx from waste incinerator flue gas

Flame-Made WO₃/CeO_x-TiO₂ Catalysts for Selective Catalytic Reduction of NO_x by NH₃

Influence of SiO₂ on M/TiO₂ (M = Cu, Mn, and Ce) Formulations for Low-Temperature Selective Catalytic Reduction of NO_x with NH₃: Surface Properties and Key Components in Relation to the Activity of NO_x Reduction

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Low-temperature catalytic reduction of NO by NH3 over vanadia-based nanoparticles prepared by flame-assisted spray pyrolysis: Influence of various supports

Cited by 105 publications

References 49 publications

Role of surface vanadium oxide coverage support on titania for the simultaneous removal of o-dichlorobenzene and NOx from waste incinerator flue gas

Role of surface vanadium oxide coverage support on titania for the simultaneous removal of o-dichlorobenzene and NOx from waste incinerator flue gas

Flame-Made WO3/CeOx-TiO2 Catalysts for Selective Catalytic Reduction of NOx by NH3

Influence of SiO2 on M/TiO2 (M = Cu, Mn, and Ce) Formulations for Low-Temperature Selective Catalytic Reduction of NOx with NH3: Surface Properties and Key Components in Relation to the Activity of NOx Reduction

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Flame-Made WO₃/CeO_x-TiO₂ Catalysts for Selective Catalytic Reduction of NO_x by NH₃

Influence of SiO₂ on M/TiO₂ (M = Cu, Mn, and Ce) Formulations for Low-Temperature Selective Catalytic Reduction of NO_x with NH₃: Surface Properties and Key Components in Relation to the Activity of NO_x Reduction