Over the past several years, cerium oxide and CeO2-containing materials have come under intense scrutiny as catalysts and as structural and electronic promoters of heterogeneous catalytic reactions. Recent developments regarding the characterization of ceria and CeO2-containing catalysts are critically reviewed with a special focus towards catalyst interaction with small molecules such as hydrogen, carbon monoxide, oxygen, and nitric oxide. Relevant catalytic and technological applications such as the use of ceria in automotive exhaust emission control and in the formulation of SO x reduction catalysts is described. A survey of the use of CeO2-containing materials as oxidation and reduction catalysts is also presented.

Catalytic Properties of Ceria and CeO2-Containing Materials

Progress in catalysis is driven by society's needs. The development of new electrocatalysts to make renewable and clean fuels from abundant and easily accessible resources is among the most challenging and demanding tasks for today's scientists and engineers. The electrochemical splitting of water into hydrogen and oxygen has been known for over 200 years, but in the last decade and motivated by the perspective of solar hydrogen production, new catalysts made of earth-abundant materials have emerged. Here we present an overview of recent developments in the non-noble metal catalysts for electrochemical hydrogen evolution reaction (HER). Emphasis is given to the nanostructuring of industrially relevant hydrotreating catalysts as potential HER electrocatalysts. The new syntheses and nanostructuring approaches might pave the way for future development of highly efficient catalysts for energy conversion.

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Nanostructured hydrotreating catalysts for electrochemical hydrogen evolution

Science and technology of novel processes for deep desulfurization of oil refinery streams: a review☆ ☆

Recent advances in the science and technology of ultra low sulfur diesel (ULSD) production

Changes in surface chemistry of activated carbons by wet oxidation

Deep desulfurization: reactions, catalysts and technological challenges

Support effects on hydrotreating catalysts

Hydrodesulphurization activity and characterization of sulphided molybdenum and cobalt—molybdenum catalysts : Comparison of Alumina-, Silica-Alumina- and Titania-Supported Catalysts

Alkaline platinum L zeolites have been studied with regard to the state of the platinum and the catalytic activity of the platinum sites in benzene hydrogenation and n-hexane dehydrocyclisation. X-ray diffraction, electron micrography and infrared studies of CO adsorption led to the conclusion that there are four types of Pt particles: large 100–600 A particles outside the channels, crystals 10–25 A in diameter and small metallic cylinders inside and outside the channels and very small particles in cavities, the latter giving reversible Pt carbonyl clusters upon CO adsorption. The Pt active sites in benzene hydrogenation and n-hexane dehydrocyclization (10–25 A crystals and small cylinders) are strongly dependent upon their environment. In the absence of any acidity their activity increases with the zeolite basicity, while no electron deficiency is observed. The infrared band at 2060–2065 cm–1 of adsorbed CO suggests that Pt particles have an excess of electrons and/or typical faces, corners or edges. It is suggested that the L zeolite structure and field induced these unusual Pt state and catalytic properties.

Platinum–zeolite interactions in alkaline L zeolites. Correlations between catalytic activity and platinum state

The activity of the conventional catalysts during hydroprocessing results from the ability of Mo(W)S2 to adsorb and activate hydrogen. The optimum of hydrogen adsorption occurs at the S/Mo(W) ratio of about 1.95. This is consistent with removal of the corner and edge sulfur atoms leading to the formation of the sulfur anion vacancies. The heterolytic dissociation, involving both metal and sulfur ions, is the predominant mode of hydrogen activation. It leads to the formation of metal–H and S–H moieties. The homolytic dissociation, occurring on the sulfur ion pairs, is much less evident. For the supported catalysts, the amount of the adsorbed hydrogen per unit of Mo(W) is significantly greater. This results from the spillover of the active hydrogen from the active phase on the support. The surface hydrogen can migrate back from the support to the active phase. Promoters, such as Ni and Co, increase the rate of adsorption, whereas their effect on the total amount of the adsorbed hydrogen is much less pronoun...

Michèle Breysse

Papers

Deep desulfurization: reactions, catalysts and technological challenges

Support effects on hydrotreating catalysts

Hydrodesulphurization activity and characterization of sulphided molybdenum and cobalt—molybdenum catalysts : Comparison of Alumina-, Silica-Alumina- and Titania-Supported Catalysts

Platinum–zeolite interactions in alkaline L zeolites. Correlations between catalytic activity and platinum state

Hydrogen activation by transition metal sulfides