https://www.lehigh.edu/operando/Publications/1999%20Titania-silica%20molec%20struc%20physico-chemical.pdf

Titania-silica as catalysts : molecular structural characteristics and physico-chemical properties

A series of TiO 2 supported manganese oxide catalysts were prepared by wet-impregnation method for the low temperature selective catalytic reduction (SCR) of NO with ammonia as a reductant. A combination of various physico-chemical techniques such as N 2 physisorption, O 2 chemisorption, TPR, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Raman were used to characterize the chemical environment of these catalysts. O 2 chemisorption and XRD results suggest that Mn exist in a well-dispersed state at below 16.7 wt.% of Mn on TiO 2 anatase (Hombikat), 7.5 wt.% on TiO 2 rutile (Kemira) and P-25 (80% anatase + 20% rutile), and in microcrystalline phase above these loading levels on respective support materials. These results also reveal that Mn interacts very well with pure anatase phase compared to rutile. XPS results of Mn/TiO 2 anatase (Hombikat) catalysts illustrated the presence of MnO 2 as a major phase (peak at 642.0 eV) along with Mn 2 O 3 as the minor phase at lower loadings. The presence of Mn 2 O 3 disappears at higher loadings. The characterization results indicated that the manganese oxide exists as an isolated species at very low loadings, highly dispersed state probably as two dimensional monolayer species at intermediate loadings, polymeric or microcrystalline form of manganese oxide at higher (above monolayer capacity) loadings was envisaged. The catalytic performance of various amounts of Mn loaded on different TiO 2 supported catalysts for low temperature SCR reaction at catalyst bed temperature 175 °C under power plant conditions using GHSV = 50,000 h −1 was studied. The catalyst with 16.7 wt.% Mn/TiO 2 anatase (Hombikat) was found to be highly active and selective catalyst for this reaction. The Raman studies acted as complimentary tool to XPS in order to characterize the manganese oxides (MnO, Mn 2 O 3 , Mn 3 O 4 , MnO 2 ). Raman data show that there is a strong interaction between the Mn oxides and the support, which is responsible for the impressive catalytic performance in comparison with other systems we investigated.

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Surface characterization studies of TiO2 supported manganese oxide catalysts for low temperature SCR of NO with NH3

Nickel-doped Mn/TiO2 as an efficient catalyst for the low-temperature SCR of NO with NH3: Catalytic evaluation and characterizations

2.7. Redox Deprotections 221 3. Thiol Protecting Groups 223 4. Carboxy Protecting Groups 223 4.1. Protection 224 4.2. Deprotection 226 5. Carbonyl Protecting Groups 227 5.1. Acetals 227 5.1.1. Protection 227 5.1.2. Deprotection 231 5.2. Dithioacetals 233 5.2.1. Protection 233 5.2.2. Deprotection 235 5.3. 1,3-Oxathiolanes 237 5.4. 1,1-Diacetates (Acylals) 238 5.4.1. Protection 238 5.4.2. Deprotection 239 5.5. Nitrogenous Derivatives 240 5.5.1. Protection 240 5.5.2. Deprotection 241 6. Amino Protecting Groups 242 6.1. Protection 242 6.2. Deprotection 244 7. Concluding Remarks 246 8. Acknowledgments 246 9. Abbreviations 246 10. References 246

Protection (and deprotection) of functional groups in organic synthesis by heterogeneous catalysis.

Structural characteristics of ceria−titania and vanadia/ceria−titania mixed oxides have been investigated using X-ray powder diffraction (XRD), Raman spectroscopy (RS), and X-ray photoelectron spectroscopy (XPS) techniques. The (1:1 mole ratio) mixed oxide was obtained by a coprecipitation method, and a nominal 5 wt % V2O5 was deposited over its surface by a wet impregnation technique. Both of the materials were then subjected to thermal treatments from 773 to 1073 K and were characterized by the above-mentioned techniques. The XRD results suggest that the CeO2−TiO2 mixed oxide calcined at 773 K primarily consists of poorly crystalline CeO2 and TiO2-anatase phases and that a better crystallization of these oxides occurs with increasing calcination temperature. The “a” cell-parameter values suggest some incorporation of titanium into the ceria lattice. Impregnation of vanadia on ceria−titania enhances the crystallization of CeO2 and TiO2 oxides. However, no crystalline V2O5 could be observed from XRD and R...

Structural Characterization of CeO2−TiO2 and V2O5/CeO2−TiO2 Catalysts by Raman and XPS Techniques

Oxygen chemisorption on titania-zirconia mixed oxide supported vanadium oxide catalysts

Reactivity of V2O5 with TiO2ZrO2 mixed oxide: An X-ray diffraction study

Mo-ZrO2 Solid Acid Catalyst For Transesterification of β-Ketoesters

Esterification by ZrO2 and Mo-ZrO2 ECO-Friendly Solid Acid Catalysts

A one step synthesis of isobutyraldehyde from methanol and ethanol over mixed oxide (TiO2-Al2O3, TiO2-SiO2, TiO2-ZrO2 and TiO2-SiO2-ZrO2) supported vanadium oxide catalysts was investigated at atmospheric pressure and 350 °C. The V2O5/TiO2-SiO2 catalyst showed a better performance in terms of total conversion and product selectivity than the other catalyst systems.

B. Manohar

Papers

Oxygen chemisorption on titania-zirconia mixed oxide supported vanadium oxide catalysts

Reactivity of V2O5 with TiO2ZrO2 mixed oxide: An X-ray diffraction study

Mo-ZrO2 Solid Acid Catalyst For Transesterification of β-Ketoesters

Esterification by ZrO2 and Mo-ZrO2 ECO-Friendly Solid Acid Catalysts

Synthesis of isobutyraldehyde from methanol and ethanol over mixed oxide supported vanadium oxide catalysts