The effect of water on the acidity of TiO2 and sulfated titania

Kulkarni, Apoorva P.; Muggli, Darrin S.

doi:10.1016/j.apcata.2006.01.033

Cited by 49 publications

(29 citation statements)

References 56 publications

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“…Some studies [51][52][53] previously stated that H 2 O may convert the Lewis sites to Brønsted sites. However, recent study [54] showed the primary effect of H 2 O on the acid sites was that H 2 O displaced the adsorbed molecules from Brønsted sites and Lewis sites rather than the conversion of Lewis sites to Brønsted sites. The acid sites were occupied by H 2 O and hence reduced the decomposition of ozone on the acid sites.…”

Section: Effect Of Inlet Ozone Concentrationmentioning

confidence: 96%

Potential use of a combined ozone and zeolite system for gaseous toluene elimination

Chao

Kwong

Hui

2007

Journal of Hazardous Materials

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Section: Effect Of Inlet Ozone Concentrationmentioning

confidence: 96%

Potential use of a combined ozone and zeolite system for gaseous toluene elimination

Chao

Kwong

Hui

2007

Journal of Hazardous Materials

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“…The MD molecule is therefore more basic in comparison with AO and therefore considered to strongly interact with surface acidic groups. Trace amounts of water molecules have been known to form H 3 O + ions with bronsted centers (Kulkarni and Muggli 2006;Richardson and Benson 1957). This interaction may explain the loss in sulfur capacity in the presence of water.…”

Section: Additivesmentioning

confidence: 98%

Characteristics of sulfur removal by silver-titania adsorbents at ambient conditions

Nair

Tatarchuk

2011

Adsorption

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Sulfur capacity of SiO 2 , TiO 2 and γ -Al 2 O 3 structures was investigated. Thermal treatment of TiO 2 and γ -Al 2 O 3 in air increased their respective sulfur capacity by 67 and 43%. Sulfur capacity was associated with surface acidity and the improvement attributed to the formation of bronsted acid sites. Addition of 4wt% transition metals further enhanced the sulfur capacity of TiO 2 with Ag indicating the highest increase. Comparison of sulfur capacity of Ag/TiO 2 with other adsorbents was made using JP5 fuel with sulfur concentration of 1172 ppmw. Ag/TiO 2 adsorbent demonstrated a saturation sulfur capacity of 8.20 mg/g. A significant loss in sulfur capacity was observed between real and model fuel compositions. Various factors resulting in this loss was investigated such as the effect of additives, competitive adsorption and the structure of sulfur heterocycles.

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“…center [19][20][21]. Obviously, the reactions in the vicinity of TiO 2 incorporated sulfate groups, leading to the formation of Ti 3? with respect to that of superacid sites in the SO 4 2-/M x O y solid acid, are promoted at high temperature by the presence of the sulfated metal oxides [1,2,10,14,18]. During the calcination, the homolytic breaking of the Ti-O (or Ti-S) bridge within the sulfated TiO 2 group leads to the reduction of the Ti 4?…”

Section: Methodsmentioning

confidence: 97%

“…It is well established that the sulfated titania superacid is an interesting and good candidate catalysing the trans-esterification or oligomerization reactions [3][4][5][6][7][8]. Recently, both the Lewis and Brønsted-acid sites are found to constitute the catalytic active sites within the solid superacid catalysts based on a number of the spectroscopic studies, Fourier-transform infrared (FT-IR), nuclear magnetic resonance (NMR), and temperature-programmed desorption (TPD), where the correlation between the type of acidity (Lewis and/or Brønsted) and the catalyst activity is evaluated [9][10][11][12][13][14][15]. However, the in situ population of these formed sulfated-acid sites dependent on high-temperature calcination is still not clear.…”

Section: Introductionmentioning

confidence: 99%

Probing the Catalytic Center of TiO2/SO4 2− Solid Superacid Catalyst by X-Band In Situ High-Temperature EPR Spectroscopy

et al. 2011

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Paramagnetic centers of the solid superacid catalyst in the sulfated TiO 2 are prone to the electron paramagnetic resonance (EPR) spectroscopy. The induction of the catalytic-active sites in TiO 2 powder presubmerged in H 2 SO 4 solution as a function of the calcinated temperature of 293-873 K is investigated by X-band in situ continuous-wave EPR measurements. Sulfated-acid sites composed of the Ti 3? ion are formed upon calcination. The overall experimental results show that the population of these sites goes uphill with the elevating temperature, reaches a maximum at *623 K and decreases afterward to close zero. During the process, the decomposition of the TiO 2 /SO 4 2-leads to the formation of Ti 3? species and then to the increasing EPR signal amplitude, and the consecutive decomposition of the sulfur at higher temperature ([650 K) to the diminishing signal. The X-ray diffraction indicates that the introduction of SO 4 2-stabilizes the geometric structure in the anatase phase.

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The effect of water on the acidity of TiO2 and sulfated titania

Cited by 49 publications

References 56 publications

Potential use of a combined ozone and zeolite system for gaseous toluene elimination

Potential use of a combined ozone and zeolite system for gaseous toluene elimination

Characteristics of sulfur removal by silver-titania adsorbents at ambient conditions

Probing the Catalytic Center of TiO2/SO4 2− Solid Superacid Catalyst by X-Band In Situ High-Temperature EPR Spectroscopy

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