Mechanism of acidity generation on sulfur-promoted metal oxides

Jin, Tuo; Yamaguchi, Tsutomu; Tanabe, Kozo

doi:10.1021/j100411a017

Cited by 340 publications

(177 citation statements)

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“…No Brønsted acid sites were observed for the parent zirconia, in accordance with previous reports [31,34,35]. In contrast, Figure 6 shows that all SZ samples exhibited BPy species (as expected from related literature [6,10]) whose concentration reached a maximum for S loadings between 1.7 and 3.1 wt %. The concentration of LPy species showed a concomitant decrease with S loading, accompanied by a slight blue-shift from 1604 cm −1 to 1610 cm −1 .…”

Section: Surface Aciditysupporting

confidence: 91%

Acidity-Reactivity Relationships in Catalytic Esterification over Ammonium Sulfate-Derived Sulfated Zirconia

et al. 2017

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New insight was gained into the acidity-reactivity relationships of sulfated zirconia (SZ) catalysts prepared via (NH 4 ) 2 SO 4 impregnation of Zr(OH) 4 for propanoic acid esterification with methanol. A family of systematically related SZs was characterized by bulk and surface analyses including XRD, XPS, TGA-MS, N 2 porosimetry, temperature-programmed propylamine decomposition, and FTIR of adsorbed pyridine, as well as methylbutynol (MBOH) as a reactive probe molecule. Increasing surface sulfation induces a transition from amphoteric character for the parent zirconia and low S loadings <1.7 wt %, evidenced by MBOH conversion to 3-hydroxy-3-methyl-2-butanone, methylbutyne and acetone, with higher S loadings resulting in strong Brønsted-Lewis acid pairs upon completion of the sulfate monolayer, which favored MBOH conversion to prenal. Catalytic activity for propanoic acid esterification directly correlated with acid strength determined from propylamine decomposition, coincident with the formation of Brønsted-Lewis acid pairs identified by MBOH reactive titration. Monodispersed bisulfate species are likely responsible for superacidity at intermediate sulfur loadings.

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Section: Surface Aciditysupporting

confidence: 91%

Acidity-Reactivity Relationships in Catalytic Esterification over Ammonium Sulfate-Derived Sulfated Zirconia

et al. 2017

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“…After NH 3 was fed into the DRIFTS cell for about 10 min, the bands at 1549 cm -1 , 1559 cm -1 due to presence of amide species (-NH 2 ) were detected Sun et al, 2009), which might be oxidized by lattice oxygen on the surface of manganese oxide (Kijlstra et al, 1997a). With the continuous injection of ammonia, the new band at 1684 cm -1 which could be attributed to the ammonium ions bond to Brønsted acid sites was detected (Jin et al, 1986;Pan et al, 2013). It was noted that several adsorbed species were detected after injection of NH 3 for about 25 min.…”

Section: Nh 3 Adsorption On Mno X /Mwcntsmentioning

confidence: 99%

In Situ DRIFTS Study of the Low Temperature Selective Catalytic Reduction of NO with NH3 over MnOx Supported on Multi-Walled Carbon Nanotubes Catalysts

Wang

Huang

2015

Aerosol Air Qual. Res.

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MnO x supported on multi-walled carbon nanotubes (MWCNTs) catalysts were prepared by the pore volume impregnation method and used for low-temperature selective catalytic reduction (SCR) of NO with NH 3 . Based on the previous study, 10 wt.% loading MnO x /MWCNTs were then selected for investigation of the reaction mechanism by in situ Diffuse Reflectance Infrared Fourier Transform spectroscopy (in-situ DRIFTS). The important intermediates in the SCR of NO x process at 210°C were discussed based on the DRIFTS results. Furthermore, the NH 3 -SCR reaction pathways over MnO x /MWCNTs catalysts were proposed. The results showed that NH 4 + species on Brønsted acid sites and coordinate ammonia species on Lewis acid sites existed during the SCR reaction. NH 4 + species was more active than coordinate ammonia species over the catalysts at 210°C. Most of NO x ad-species would react with NH 3 ad-species. However, nitrite species, bidentate and monodentate nitrates contributed to the SCR reaction over the catalysts mostly. Two possible reaction pathways were proposed. One was that NO x ad-species could react with NH 4 + to form intermediate of NH 4 N 2 O 4 (a), NH 4 NO 2 (a) or NH 4 NO 3 (a), then to produce N 2 and H 2 O as the final products. The other pathway was that NH 3 was initially adsorbed on active site and NH 2 was formed, then NH 2 reacted with NO x ad-species to produce intermediate NH 2 NO 2 or NH 2 NO 3 which were unstable and would decompose into N 2 and H 2 O.

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“…The preparations of sulfated metallic oxides were generally carried out through the impregnation of TiO 2 with H 2 SO 4 or (NH 4 ) 2 SO 4 , which needed the subsequent high temperature calcinations 1) . Therefore, there exist a determinant in uence on the sintering kinetics, photochemical processes, and adsorption of gas phase components.…”

Section: Introductionmentioning

confidence: 99%

Surface Sulfation Chemistry, Structural and Chemical Activities of High Pure Anatase TiO<sub>2</sub> Nanocrystals

Yan

2017

Mater. Trans.

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Sulfated anatase TiO 2 nanocrystals were prepared by hydrothermal method. All samples were characterized by means of powder XRD and FT-IR. It is shown that all the as-prepared samples displayed the features of pure anatase phase. The surface hydration and sulfation of TiO 2 became signi cantly enhanced as decreasing the particle size. The sulfated TiO 2 nanocrystals showed photoactivities towards photodegradation of RhB under UV light irradiation, during which the sulfate species anchored on surfaces of anatase nanocrystals were not released into the reaction solutions.

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Mechanism of acidity generation on sulfur-promoted metal oxides

Cited by 340 publications

References 0 publications

Acidity-Reactivity Relationships in Catalytic Esterification over Ammonium Sulfate-Derived Sulfated Zirconia

Acidity-Reactivity Relationships in Catalytic Esterification over Ammonium Sulfate-Derived Sulfated Zirconia

In Situ DRIFTS Study of the Low Temperature Selective Catalytic Reduction of NO with NH3 over MnOx Supported on Multi-Walled Carbon Nanotubes Catalysts

Surface Sulfation Chemistry, Structural and Chemical Activities of High Pure Anatase TiO<sub>2</sub> Nanocrystals

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