Photoinduced reactivity of titanium dioxide

Owing to the increasing emissions of carbon dioxide (CO2), human life and the ecological environment have been affected by global warming and climate changes. To mitigate the concentration of CO2 in the atmosphere various strategies have been implemented such as separation, storage, and utilization of CO2. Although it has been explored for many years, hydrogenation reaction, an important representative among chemical conversions of CO2, offers challenging opportunities for sustainable development in energy and the environment. Indeed, the hydrogenation of CO2 not only reduces the increasing CO2 buildup but also produces fuels and chemicals. In this critical review we discuss recent developments in this area, with emphases on catalytic reactivity, reactor innovation, and reaction mechanism. We also provide an overview regarding the challenges and opportunities for future research in the field (319 references).

Recent advances in catalytic hydrogenation of carbon dioxide

The open literature concerning chemical and mechanistic aspects of the selective catalytic reduction of NO by ammonia (SCR process) on metal oxide catalysts is reviewed. Catalytic systems based on supported V2O5 (including the industrial TiO2-supported V2O5–WO3 and/or V2O5–MoO3 catalysts) and catalysts containing Fe2O3, CuO, MnOx and CrOx are considered. The results of spectroscopic studies of the adsorbed surface species, adsorption–desorption measurements, flow reactor and kinetic experiments are analyzed. The proposed reaction mechanisms are described and critically discussed. Points of convergence and of disagreement are underlined.

Chemical and mechanistic aspects of the selective catalytic reduction of NOx by ammonia over oxide catalysts: A review

Cerium dioxide (CeO2, ceria) is becoming an ubiquitous constituent in catalytic systems for a variety of applications. 2016 sees the 40th anniversary since ceria was first employed by Ford Motor Company as an oxygen storage component in car converters, to become in the years since its inception an irreplaceable component in three-way catalysts (TWCs). Apart from this well-established use, ceria is looming as a catalyst component for a wide range of catalytic applications. For some of these, such as fuel cells, CeO2-based materials have almost reached the market stage, while for some other catalytic reactions, such as reforming processes, photocatalysis, water-gas shift reaction, thermochemical water splitting, and organic reactions, ceria is emerging as a unique material, holding great promise for future market breakthroughs. While much knowledge about the fundamental characteristics of CeO2-based materials has already been acquired, new characterization techniques and powerful theoretical methods are dee...

Fundamentals and Catalytic Applications of CeO2-Based Materials

The infrared spectral performance of the N x O y species observed on oxide surfaces [N2O, NO−, NO, (NO)2, N2O3, NO+, NO2 − (different nitro and nitrito anions), NO2, N2O4, N2O5, NO2, and NO3 − (bridged, bidentate, and monodentate nitrates)] is considered. The spectra of related compounds (N2, H-, and C-containing nitrogen oxo species, C─N species, NH x species) are also briefly discussed. Some guidelines for spectral identification of N x O y adspecies are proposed and the transformation of the nitrogen oxo species on catalyst surfaces are regarded.

Identification of Neutral and Charged N x O y Surface Species by IR Spectroscopy

Reactivity and Physicochemical Characterization of V2O5-WO3/TiO2 De-NOx Catalysts

NOx Storage Reduction over PtBa/γ-Al2O3 Catalyst

Characterization and Reactivity of V2O5–MoO3/TiO2 De-NOx SCR Catalysts

The interaction of NO, NO2, or NO/O2 mixtures with Pt/Al2O3, Ba/Al2O3, and Pt−Ba/Al2O3 catalysts has been investigated by IR spectroscopy and temperature-programmed desorption. Upon NO interaction, small amounts of nitrites, nitrates, and hyponitrite species were formed on the Ba-containing samples. The NOx storage capacity of the catalysts was highly enhanced upon adsorption of NO/O2 mixtures and further upon NO2 admission. Upon adsorption of NO/O2 on Pt/Al2O3 sample nitrites, nitrates and NO2δ+ species were mainly formed, showing a moderate thermal stability. Barium markedly increased the amount and stability of the stored NOx species, which were bidentate and monodentate nitrites and, in minor amounts, nitrates. Nitrites were removed below 750 K and/or transformed into ionic Ba nitrates, stable up to 800−900 K. Upon NO2 adsorption, huge amounts of nitrates, but no nitrites, were formed on all the samples. Also in this case, Ba increased the amount and stability of the stored NOx species. The nature and...

Luca Lietti

Papers

Chemical and mechanistic aspects of the selective catalytic reduction of NOx by ammonia over oxide catalysts: A review

Reactivity and Physicochemical Characterization of V2O5-WO3/TiO2 De-NOx Catalysts

NOx Storage Reduction over PtBa/γ-Al2O3 Catalyst

Characterization and Reactivity of V2O5–MoO3/TiO2 De-NOx SCR Catalysts

FT-IR and TPD investigation of the NOx storage properties of BaO/Al2O3 and Pt-BaO/Al2O3 catalysts