Browsing by Subject "Cerium compounds"

Article

Ceria-based materials for hydrogen production via hydrocarbon steam reforming and water-gas shift reactions

Polychronopoulou, Kyriaki; Kalamaras, Christos M.; Efstathiou, Angelos M. (2011)

This review paper provides an overview of the use of ceria-based catalytic materials towards the industrial hydrogen production via the hydrocarbon steam reforming and the water-gas shift reaction routes with a focus on ...

Article

The effect of calcination temperature on the oxygen storage and release properties of CeO2 and Ce-Zr-O metal oxides modified by phosphorus incorporation

Larese, C.; López Granados, M.; Mariscal, R.; Fierro, José Luis García; Lambrou, Panayiota S.; Efstathiou, Angelos M. (2005)

The present work reports on the effects of calcination temperature (T c) on the oxygen storage and release properties of CeO2 and Ce0.8Zr0.2O2 solids deliberately contaminated with CePO4. Pulsed-feed and stepped-feed dynamic ...

Article

The effect of La3+-doping of CeO2 support on the water-gas shift reaction mechanism and kinetics over Pt/Ce1-xLaxO2-δ

Kalamaras, Christos M.; Petallidou, Klito C.; Efstathiou, Angelos M. (2013)

Platinum nanoparticles (dPt=1.0-1.2nm) supported on single CeO2 and La2O3 metal oxides and Ce0.8La0.2O2-δ solid solution were prepared to investigate for the first time the effect of La3+-doping of ceria on important ...

Article

Effect of thermal aging on the transient kinetics of oxygen storage and release of commercial Cex Zr1-x O2-based solids

Christou, Stavroula Y.; Bradshaw, H.; Butler, C.; Darab, J.; Efstathiou, Angelos M. (2009)

The use of powerful analytical methodologies for the evaluation of the performance of commercial oxygen storage materials based on oxygen transient isothermal isotopic exchange experiments is illustrated in this study. Ce ...

Article

Effects of calcination temperature on the stability of CePO4 detected in vehicle-aged commercial three-way catalysts

Larese, C.; Cabello Galisteo, F.; López Granados, M.; Mariscal López, R.; Fierro, José Luis García; Lambrou, Panayiota S.; Efstathiou, Angelos M. (2004)

Samples extracted from a vehicle-aged commercial TWC monolith (the inlet part of the first cartridge) have been shown to contain CePO4. The effects of calcination temperature in the 773-1173K range on these samples have ...

Article

Effects of reaction temperature and support composition on the mechanism of water - Gas shift reaction over supported-Pt catalysts

Kalamaras, Christos M.; Gonzalez, I. D.; Navarro, R. M.; Fierro, José Luis García; Efstathiou, Angelos M. (2011)

The present work reports on a detailed study of the effect of support chemical composition and reaction temperature on the mechanism of the water-gas shift (WGS) reaction over supported-Pt catalysts. The effect of the same ...

Article

Industrial H2-SCR of NO on a novel Pt/MgO-CeO2 catalyst

Costa, Costas N.; Savva, Petros G.; Fierro, José Luis García; Efstathiou, Angelos M. (2007)

We describe here the performance of a novel MgO-CeO2-supported Pt (0.1 wt%) catalyst towards the selective conversion of NO into N2 (SN2 > 80%) by using H2 (H2-SCR) under process conditions similar to those encountered in ...

Article

Investigation of the synthesis and properties of ternary V-Cu-Ce Oxides of Composition VxCuxCe1-2xO2

Attipa, Christothea; Theocharis, Charis R. (2009)

Aco-precipitation method has been used to prepare ternary mixed oxides based on ceria with the general formula VxCuxCe 1-2xO2, where x was varied between 0.05 and 0.45. The structural and surface properties as well as the ...

Article

Low-temperature purification of gas streams from phenol by steam reforming over novel supported-Rh catalysts

Constantinou, D. A.; Efstathiou, Angelos M. (2010)

The purification of gas streams from phenol at low-temperatures (350-550 °C) was investigated by its reaction with steam over novel catalytic systems, namely 0.5 wt% Rh supported on Ce0.15Zr0.85O2, Ce0.15Zr0.83Mg0.02O2 and ...

Article

Mechanistic aspects of the H2-SCR of NO on a Novel Pt/MgO-CeO2 catalyst

Costa, Costas N.; Efstathiou, Angelos M. (2007)

Steady State Isotopic Transient Kinetic Analysis (SSITKA) coupled with Temperature-Programmed Surface Reaction (TPSR) experiments, using on line Mass Spectroscopy (MS) and in situ DRIFTS have been performed to study essential ...

Article

Mechanistic studies of the water-gas shift reaction over Pt/Ce xZr1-xO2 catalysts: The effect of Pt particle size and Zr Dopant

Kalamaras, Christos M.; Dionysiou, Dionysios Demetriou D.; Efstathiou, Angelos M. (2012)

A series of y wt % Pt/CexZr1-xO2 catalysts (y = 0.1, 0.5, and 1.0

Article

Mixed Transition-Metal - Lanthanide Complexes at Higher Oxidation States: Heteronuclear CeIV-MnIV Clusters

Tasiopoulos, Anastasios J.; O'Brien, T. A.; Abboud, K. A.; Christou, George (2004)

Wheels within wheels: A new family of mixed cerium(IV)-manganese(IV) clusters has been prepared spanning a range of Ce:Mn ratios from 3:2 to 1:6. The unusual core of the latter CeMn6 complex is shown (Ce green, Mn blue, O ...

Article

The phenol steam reforming reaction over MgO-based supported Rh catalysts

Polychronopoulou, Kyriaki; Fierro, José Luis García; Efstathiou, Angelos M. (2004)

The phenol steam reforming reaction toward H2 formation has been investigated in the 575-730°C range over MgO, CeO2, and ZrO 2 single metal oxides and various mixed metal oxides such as Mg-Ce-O, Mg-Zr-O, and Mg-Ce-Zr-O, ...

Article

Preparation and characterization of a cerium(IV)-incorporated manganese oxide OMS-2. Effect of cerium(IV) template on octahedral molecular sieves of manganese oxide and characterization of manganese oxide molecular sieves with cerium(IV) as dopant

Hapeshi, Evroula; Theocharis, Charis R. (2008)

The manganese oxide material K-OMS-2 was synthesized both via a redox reaction between potassium permanganate and manganese nitrate in an acidic medium (nitric acid) under reflux conditions and by the sol-gel reaction ...

Article

Preparation and characterization of nanoporous ceria containing heteroatoms, with and without a matrix

Theocharis, Charis R.; Kyriakou, Georgia; Christophidou, Maria (2005)

We have been interested in the synthesis and study of porous ceria, because of its importance in several catalytic applications, and notably in automobile exhaust catalysts. The mesoporosity of these solids is susceptible ...

Article

"Redox" vs "associative formate with -OH group regeneration" WGS reaction mechanism on Pt/CeO2: Effect of platinum particle size

Kalamaras, Christos M.; Americanou, Sofia; Efstathiou, Angelos M. (2011)

A series of x wt.% Pt/CeO2 catalysts (x = 0.1-2.0) was prepared to investigate for the first time the effect of Pt particle size on important kinetic and mechanistic aspects of the water-gas shift (WGS) reaction, namely ...

Article

Study of the crystallization of nanoporous mixed metal oxide phases

Theocharis, Charis R.; Attipa, Christothea; Hapeshi, Evroula; Tillirou, Aphrodite A.; Kokkinofta, Rebecca I. (2008)

A systematic study of the synthesis and characterization of pristine ceria and of mixed cerium/metal oxides has been undertaken. Various synthetic routes were explored, with the crystallization process being examined via ...

Article

Suppression of the oxygen storage and release kinetics in Ce0.5Zr0.5O2 induced by P, Ca and Zn chemical poisoning

Christou, Stavroula Y.; Álvarez-Galván, M. C.; Fierro, José Luis García; Efstathiou, Angelos M. (2011)

The present investigation concerns for the first time the understanding of the individual and combined effects of phosphorous with calcium or zinc deposited on a Ce0.5Zr0.5O2 solid followed by calcination in 20%O2/He at ...

Article

Synthesis and characterization of mesoporous cerium oxide prepared using an organic base and a templating agent

Tillirou, Aphrodite A.; Theocharis, Charis R. (2008)

This paper discusses the effect on the surface properties of precipitated cerium oxide of using a mixed alcohol-water solvent as well as an organic base instead of the ammonia solution used hitherto. It further discusses ...

Article

Using statistical analysis as an additional tool in porous solid characterization

Attipa, Christothea; Panayiotou, Antonia; Kokkinofta, Rebecca I.; Theocharis, Charis R. (2011)

Analytical chemists have long used statistical methods to help them organize and interpret experimental data-especially where large numbers of these are generated-as well as to help them design new experiments. Recently, ...