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

Oxidation into CO2 is a major solution to CO abatement in air depollution treatments. The development of catalytic converters led to an extraordinary high number of publications on metal catalysts during the last fifty years. Due to the increasing price of noble metals and to remarkable progresses in oxide syntheses, catalytic oxidation of carbon monoxide over oxide catalysts has recently gained in interest, even if some oxides are known to present remarkable activity since the beginning of the 20th century. In this Review, the kinetics and mechanism of CO oxidation on single and mixed oxides are examined, alongside the catalyst structures

Catalytic Oxidation of Carbon Monoxide over Transition Metal Oxides

The rapid development in recent years of the proton-exchange membrane (PEM) fuel cell technology has stimulated research in all areas of fuel processor catalysts for hydrogen generation. The principal aim is to develop more active catalytic systems that allow for the reduction in size and increase the efficiency of fuel processors. The overall selectivity in generating a low CO content hydrogen stream as needed by the PEM fuel cell catalyst is dependent on the efficiency of the catalysts in each segment of the fuel processor. This article reviews the advances achieved during the past few years in the development of catalytic materials for hydrogen generation through fuel reforming, 1 water-gas shift and carbon monoxide preferential oxidation, as used or aimed to be of use in fuel processing for PEM fuel cell systems.

Review of fuel processing catalysts for hydrogen production in PEM fuel cell systems

Nanostructured CeO2–ZrO2 mixed oxides have attracted great interest in the past 10 years, in particular as redox or oxygen storage promoters in the three-way catalysts. However, it has now became clear that both the chemistry of the simple oxides and the complex metal–CeO2-based oxide interactions can play a critical role in developing novel and highly active materials for a number of processes, ranging from catalysts for H2 production from fuels up to ceramic materials and solid state conductors for fuel cells. Despite the apparent simplicity of these systems, extreme variability of their chemical and textural properties has been observed. An attempt is made here to rationalise the various factors and the inter-connections to the structure, the texture, and the effects of the nanometre scale, which all contribute to the properties of these materials.

Nanostructured CeO2–ZrO2 mixed oxides

Preferential CO oxidation in hydrogen (PROX) on ceria-supported catalysts, part I: Oxidation state and surface species on Pt/CeO2 under reaction conditions

Investigation of the oxygen storage process on ceria- and ceria–zirconia-supported catalysts

Towards the comprehension of oxygen storage processes on model three-way catalysts

The 20 wt.% V2O5–TiO2 catalyst was prepared by the sol–gel route and calcined at 300 °C. XRD, TEM, EDX and FT-IR analysis showed that the material presents a crystalline structure with the presence of both TiO2 rutile and anatase varieties. BET analysis showed a low oxide surface area (27 m2/g). Cyclohexane oxidation with hydrogen peroxide in presence of the catalyst showed a low conversion. The use of acetic acid as solvent and acetone as initiator presented an approximate 8% conversion into cyclohexanol, with 76% selectivity.

Preparation and characterization of 20 wt.% V2O5–TiO2 catalyst oxidation of cyclohexane

The present work aims to study the photocatalytic degradation and inhibitor corrosion properties of based on CeO2 nanoparticles (CeNPs). Moreover, this article seeks to investigate the effect of doping CeNPs by plasmonic nanoparticles, as gold (AuNPs), silver (AgNPs) and platinum (PtNPs). CeNPs are obtained by a precipitation process, while the deposition precipitation using urea (DPU) method was chosen to dope the CeNPs. The physicochemical characteristics of materials have performed using various techniques such as: XRD, RD/UV–vis, FTIR, BET, and TG-DTA analysis. The photocatalytic performance of the synthesized nanomaterials was investigated in terms of their efficiency for the photodegradation of methyl orange (MO) in an aqueous solution under different illumination (UVA and UVC). The degradation rates exceeding 92 % could be achieved in very short times depending on the dopant and the illumination nature. However, the corrosion inhibition properties of synthesized nanomaterials on mild steel in acid medium (hydrochloric acid, 1 N) were estimated using a weight loss method. The inhibition efficiency achieved 80–96 % and increase with concentration. It was concluded that the studied nanomaterials are a potential photocatalysts and corrosion inhibitors.

Photocatalytic and corrosion inhibitor performances of CeO2 nanoparticles decorated by noble metals: Au, Ag, Pt

a b s t r a c t VO2-SiO2 based catalysts with V contents between 5 and 20 wt.% were prepared from inorganic precursors via the sol-gel process and subsequently dried, calcined and reduced at 673 K. Struc- tural characterization of these materials was carried out with X-rays diffraction (XRD), ICP, N2 adsorption-desorption at 77 K, UV-vis diffused reflectance spectroscopy (DR UV-vis), FTIR and pyri- dine adsorption followed by FTIR. Their catalytic activities in the cyclohexene epoxidation with TBHP as oxidant and heptane as solvent were also examined. Results of XRD and DR UV-visible spectroscopy revealed that VO2 species are well dispersed on silica. BET analysis showed that the surface area decreases from 390 to 22 m2 g−1 with V content. The results of pyridine adsorption followed by FTIR indicated that the 5 wt.% VO2-SiO2 catalyst displays low acid densities. Experimental results pointed out that the 5 wt.% VO2-SiO2 catalysts offer excellent activity. The obtained cyclohexene conversion and selectivity toward epoxide are 21% and 84% respectively. A reaction mechanism explaining clearly epoxidation versus allylic oxidation is proposed. © 2014 Elsevier B.V. All rights reserved.

Sumeya Bedrane

Papers

Investigation of the oxygen storage process on ceria- and ceria–zirconia-supported catalysts

Towards the comprehension of oxygen storage processes on model three-way catalysts

Preparation and characterization of 20 wt.% V2O5–TiO2 catalyst oxidation of cyclohexane

Photocatalytic and corrosion inhibitor performances of CeO2 nanoparticles decorated by noble metals: Au, Ag, Pt

Liquid phase cyclohexene oxidation over vanadia based catalysts with tert-butyl hydroperoxide: Epoxidation versus allylic oxidation