Browsing by Subject "Catalyst activity"

Article

Catalytic behavior of La-Sr-Ce-Fe-O mixed oxidic/perovskitic systems for the NO+CO and NO+CH4+O2 (lean-NOx) reactions

Belessi, Vassiliki C.; Costa, Costas N.; Bakas, Thomas V.; Anastasiadou, T.; Pomonis, Phillippos J.; Efstathiou, Angelos M. (2000)

Mixed oxides of the general formula La0.5SrxCeyFeOz were prepared by using the nitrate method and characterized by XRD and Mossbauer techniques. The crystal phases detected were perovskites LaFeO3 and SrFeO3-x and oxides ...

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

Comparative study of La-Sr-Fe-O perovskite-type oxides prepared by ceramic and surfactant methods over the CH4 and H2 lean-deNOx

Stathopoulos, Vassilis N.; Belessi, Vassiliki C.; Bakas, Thomas V.; Neophytides, Stylianos G.; Costa, Costas N.; Pomonis, Phillippos J.; Efstathiou, Angelos M. (2009)

Mixed oxides of the general formula La0.8Sr0.2FeO3-x were prepared by ceramic and surfactant methods and tested towards the NO/H2/O2 and NO/CH4/O2 lean-deNOx reactions in the 200-450 °C range. The materials were characterized ...

Article

A comparative study of the steam reforming of phenol towards H2 production over natural calcite, dolomite and olivine materials

Constantinou, D. A.; Fierro, José Luis García; Efstathiou, Angelos M. (2010)

Pre-calcined (air, 850 °C) naturally occurring calcite, dolomite and olivine materials were studied for phenol steam reforming towards H2 production. The effect of reaction temperature, feed volume flow rate, and hydrogen ...

Article

Deactivation of Pd/Ce 0.5Zr 0.5O 2 model three-way catalyst by P, Ca and Zn deposition

Christou, Stavroula Y.; García-Rodríguez, S.; Fierro, José Luis García; Efstathiou, Angelos M. (2012)

The negative effects of P, P-Ca and P-Zn deposition on the surface of a model 1wt% Pd/Ce 0.5Zr 0.5O 2 " three-way" catalyst (TWC) on its structural, morphological, textural, oxygen storage and release, and catalytic ...

Article

Dry reforming of methane over 5 wt% Ni/Ce1-xPrxO2-δ catalysts: Performance and characterisation of active and inactive carbon by transient isotopic techniques

Vasiliades, Michalis A.; Makri, M. M.; Djinović, P.; Erjavec, B.; Pintar, A.; Efstathiou, Angelos M. (2016)

The effects of Ce1-xPrxO2-δ support composition (x = 0.0–0.8) and reaction temperature (550–750 °C) on the catalytic activity and selectivity and important features of the mechanism of the dry reforming of methane (DRM) ...

Article

The effect of Fe on the catalytic behavior of model Pd-Rh/CeO2-Al2O3 three-way catalyst

Lambrou, Panayiota S.; Savva, Petros G.; Fierro, José Luis García; Efstathiou, Angelos M. (2007)

The present work attempts to address the issue whether iron (Fe) which is accumulated on the surface of "three-way" catalysts (TWCs) used in gasoline-driven cars is a true chemical poison of their catalytic activity. This ...

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 support composition on the origin and reactivity of carbon formed during dry reforming of methane over 5 wt% Ni/Ce1-xMxO2-δ (M = Zr4+, Pr3+) catalysts

Makri, M. M.; Vasiliades, Michalis A.; Petallidou, Klito C.; Efstathiou, Angelos M. (2016)

Carbon dioxide reforming of methane to synthesis gas in the 550-750°C range over 5 wt% Ni/Ce1-xMxO2-δ (M = Zr4+, Pr3+) solids has been investigated with respect to the effects of support chemical composition and reaction ...

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

Influence of oxychlorination treatments on the redox and oxygen storage and release properties of thermally aged Pd-Rh/CexZr1-xO 2/Al2O3 model three-way catalysts

Daley, R. A.; Christou, Stavroula Y.; Efstathiou, Angelos M.; Anderson, J. A. (2005)

Model Pd-Rh/Al2O3 three-way catalysts with and without CexZr1-xO2 as oxygen storage component have been compared in their fresh, thermally aged and oxychlorinated treated surface states to determine the potential regenerating ...

Article

The influence of reaction temperature on the chemical structure and surface concentration of active NOx in H2-SCR over Pt/MgO{single bond}CeO2: SSITKA-DRIFTS and transient mass spectrometry studies

Savva, Petros G.; Efstathiou, Angelos M. (2008)

Steady-state isotopic transient kinetic analysis (SSITKA), transient isothermal, and temperature-programmed surface reaction in H2 (H2-TPSR) techniques coupled with online mass spectroscopy (MS) and in situ diffuse reflectance ...

Article

Kinetics of methane oxidative coupling on zinc-doped titanium oxide

Efstathiou, Angelos M.; Boudouvas, D.; Vamvuka, Despina; Verykios, Xenophon E. (1992)

A kinetic study of methane conversion to C2-hydrocarbons was conducted by cofeeding methane and oxygen at 1 bar total pressure over a series of zinc-doped TiO2 catalysts. The zinc dopant concentration was varied between 1 ...

Article

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

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

The selective catalytic reduction of NO by H2 under strongly oxidizing conditions (H2-SCR) in the low-temperature range of 100-200 °C has been studied over Pt supported on a series of metal oxides (e.g., La2O3, MgO, Y2O3, ...

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

Low-temperature water-gas shift on Pt/Ce0.5La0.5O2 - δ: Effect of support synthesis method

Petallidou, Klito C.; Boghosian, Soghomon; Efstathiou, Angelos M. (2015)

A series of 0.5 wt% Pt/Ce0.5La0.5O2 - δ (Ce:La = 1:1) catalysts, the supports of which were prepared by different methods, namely: (i) sol-gel using citrate or oxalate as complexing agent, (ii) pechini, and (iii) urea ...

Article

Low-temperature water-gas shift on Pt/Ce1-xLaxO2-δ: Effect of Ce/La ratio

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

Pt nanoparticles (1.0-1.4nm size) supported on Ce1-xLaxO2-δ (x=0.0, 0.2, 05, 0.8 and 1.0) carriers, the latter prepared by the citrate sol-gel method, were tested toward the water-gas shift (WGS) reaction in the 200-400°C ...

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 aspects of the water-gas shift reaction on alumina-supported noble metal catalysts: In situ DRIFTS and SSITKA-mass spectrometry studies

Olympiou, G. G.; Kalamaras, Christos M.; Zeinalipour-Yazdi, Constantinos D.; Efstathiou, Angelos M. (2007)

Steady-state isotopic transient kinetic analysis (SSITKA) experiments coupled with mass spectrometry were performed for the first time to study essential mechanistic aspects of the water-gas shift (WGS) reaction over ...

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