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

Traditional analysis of reactions catalyzed by supported metals involves the structure of the metallic particles. However, we report here that for the class of nanostructured gold- or platinum-cerium oxide catalysts, which are active for the water-gas shift reaction, metal nanoparticles do not participate in the reaction. Nonmetallic gold or platinum species strongly associated with surface cerium-oxygen groups are responsible for the activity.

http://science.sciencemag.org/content/sci/301/5635/935.full.pdf

Active Nonmetallic Au and Pt Species on Ceria-Based Water-Gas Shift Catalysts

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 direct electrochemical oxidation of dry hydrocarbon fuels to generate electrical power has the potential to accelerate substantially the use of fuel cells in transportation and distributed-power applications1. Most fuel-cell research has involved the use of hydrogen as the fuel, although the practical generation and storage of hydrogen remains an important technological hurdle2. Methane has been successfully oxidized electrochemically3,4,5,6, but the susceptibility to carbon formation from other hydrocarbons that may be present or poor power densities have prevented the application of this simple fuel in practical applications1. Here we report the direct, electrochemical oxidation of various hydrocarbons (methane, ethane, 1-butene, n-butane and toluene) using a solid-oxide fuel cell at 973 and 1,073 K with a composite anode of copper and ceria (or samaria-doped ceria). We demonstrate that the final products of the oxidation are CO2 and water, and that reasonable power densities can be achieved. The observation that a solid-oxide fuel cell can be operated on dry hydrocarbons, including liquid fuels, without reforming, suggests that this type of fuel cell could provide an alternative to hydrogen-based fuel-cell technologies.

Direct oxidation of hydrocarbons in a solid-oxide fuel cell

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

Mining, production, application and safety issues of cerium-based materials, K. Schermanz structural properties and nonstoichiometric behaviour of CeO2, A. Trovarelli synthesis and modification of ceria-based materials, G. Adachi and T. Masui chemical and nanostructural aspects of the preparation and characterization of ceria and ceria-based mixed oxide-supported metal catalysts, S. Bernal et al studies of ceria-containing catalysts using magnetic resonance and X-ray based spectroscopies, J.C. Conesa et al structural properties and thermal stability of ceria-zirconia and related materials, J. Kaspar and P. Fornasiero oxygen storage/redox capacity and related phenomena on ceria-based catalysts, D. Duprez and C. Descorme computer simulation studies of ceria-based oxides, M. Saiful Islam and G. Balducci ceria surfaces and films for model catalytic studies using surface analysis techniques, S.H. Overbury and D.R. Mullins ceria and other oxygen storage components in automotive catalysts, M. Shelef et al SO2 poisoning of ceria-supported, metal catalysts, R.J. Gorte and T. Luo cerium and platinum based diesel fuel additives in the diesel soot abatement technology, M. Makkee et al fundamentals and applications of ceria in combustion reactions, M. Primet and E. Garbowski ceria-based wet-oxidation catalysts, S. Imamura ceria-based electrodes, M. Mogensen the use of ceria in FCC, dehydrogenation and other catalytic applications, M. Boaro et al.

Catalysis by Ceria and Related Materials

The utilization of ceria in industrial catalysis

Rh-Loaded CeO2-ZrO2 Solid-Solutions as Highly Efficient Oxygen Exchangers: Dependence of the Reduction Behavior and the Oxygen Storage Capacity on the Structural-Properties

Engineering the shape and size of catalyst particles and the interface between different components of heterogeneous catalysts at the nanometer level can radically alter their performances. This is particularly true with CeO2-based catalysts, where the precise control of surface atomic arrangements can modify the reactivity of Ce4+/Ce3+ ions, changing the oxygen release/uptake characteristics of ceria, which, in turn, strongly affects catalytic performance in several reactions like CO, soot, and VOC oxidation, WGS, hydrogenation, acid–base reactions, and so on. Despite the fact that many of these catalysts are polycrystalline with rather ill-defined morphologies, experimental and theoretical studies on well-defined nanocrystals have clearly established that the exposure of specific facets can increase/decrease surface oxygen reactivity and metal–support interaction (for supported metal nanoparticles), consequently affecting catalytic reactions. Here, we want to address the most recent developments in this...

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Alessandro Trovarelli

Papers

Catalytic Properties of Ceria and CeO2-Containing Materials

Catalysis by Ceria and Related Materials

The utilization of ceria in industrial catalysis

Rh-Loaded CeO2-ZrO2 Solid-Solutions as Highly Efficient Oxygen Exchangers: Dependence of the Reduction Behavior and the Oxygen Storage Capacity on the Structural-Properties

Ceria Catalysts at Nanoscale: How Do Crystal Shapes Shape Catalysis?