Browsing by Author "Efstathiou, Angelos M."
Now showing items 41-60 of 153
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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 ...
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The effect of Ti4+ dopant in the 5 wt% Ni/Ce1-xTixO2-δ catalyst on the carbon pathways of dry reforming of methane studied by various transient and isotopic techniques
Damaskinos, C. M.; Vasiliades, M. A.; Efstathiou, Angelos M. (2019)The carbon pathways in the dry reforming of methane with carbon dioxide (DRM) towards syngas at 750 °C have been investigated for the first time over 5 wt% Ni supported on Ti4+-doped ceria using various transient and ...
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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 ...
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The effects of Fe on the oxygen storage and release properties of model Pd-Rh/CeO2-Al2O3 three-way catalyst
Lambrou, Panayiota S.; Efstathiou, Angelos M. (2006)This work attempts to gain fundamental information about the role of Fe in the chemical deactivation of a three-way catalyst (TWC), with Fe originating from materials used in the construction of automotive engines and ...
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The effects of P-poisoning of CexZr1-xO2 on the transient oxygen storage and release kinetics
Christou, Stavroula Y.; Efstathiou, Angelos M. (2013)The present work reports on the investigation of the effects of chemical poisoning of CexZr1-xO2 solids by phosphorous (P) on the kinetics of oxygen storage and release (OSR) of the thus derived P-contaminated solids, as ...
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Effects of Pd particle size on the rates of oxygen back-spillover and CO oxidation under dynamic oxygen storage and release measurements over Pd/CeO2 catalysts
Christou, Stavroula Y.; Efstathiou, Angelos M. (2007)A kinetic mathematical model has been applied to investigate for the first time the effects of Pd particle size on the rates of oxygen back-spillover and CO oxidation during Oxygen Storage Capacity (OSC) measurements under ...
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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 ...
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Effects of sol-gel synthesis on 5Fe-15Mn-40Zn-40Ti-O mixed oxide structure and its H2S removal efficiency from industrial gas streams
Polychronopoulou, Kyriaki; Efstathiou, Angelos M. (2009)A novel Fe-Mn-Zn-Ti-O mixed metal oxide has been developed for efficient low-temperature (25-50°C) removal of H2S from a gas mixture containing 600 ppm H2S, 25 vol% H2, 7.5 vol % CO 2, and 1-3 vol% H2O that simulates typical ...
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Effects of the CePO 4 on the oxygen storage and release properties of CeO 2 and Ce 0.8Zr 0.2O 2 solid solution
Larese, C.; Galisteo, F. C.; Granados, M. L.; Mariscal, R.; Fierro, José Luis García; Lambrou, Panayiota S.; Efstathiou, Angelos M. (2004)In an attempt to gain fundamental information about the role of P on the chemical deactivation of a three-way catalyst (TWC), P was deliberatively incorporated in CeO 2 and Ce 0.8Zr 0.2O 2 solid solution. XRD, Raman, XPS, ...
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The effects of the use of weak organic acids on the improvement of oxygen storage and release properties of aged commercial three-way catalysts
Lambrou, Panayiota S.; Christou, Stavroula Y.; Fotopoulos, Apostolos P.; Foti, F. K.; Angelidis, Thomas N.; Efstathiou, Angelos M. (2005)The efficiency of weak organic acid solutions for improving the oxygen storage and release properties of aged commercial three-way catalysts (TWC) has been investigated. For the first time, three candidate leaching solutions, ...
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Effects of W6+ doping of TiO2 on the reactivity of supported Rh toward NO: Transient FTIR and mass spectroscopy studies
Chafik, T.; Efstathiou, Angelos M.; Verykios, Xenophon E. (1997)The transient adsorption and dissociation of NO over Rh supported on undoped and W6+-doped TiO2 in the temperature range of 25-450°C has been studied by FTIR and mass spectroscopy. It was found that at 25 °C three kinds ...
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Efficient in-situ regeneration method of the catalytic activity of aged TWC
Christou, Stavroula Y.; Efstathiou, Angelos M. (2007)The expansion of durability of deactivated "three-way" catalysts (TWCs) used in gasoline-driven cars by applying efficient, economically viable and environmentally friendly methods for the in situ regeneration of their ...
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Elucidation of mechanistic and kinetic aspects of water-gas shift reaction on supported Pt and Au catalysts via transient isotopic techniques
Efstathiou, Angelos M. (2016)With growing interest in hydrogen fuel cell applications, novel and robust water-gas shift (WGS) industrial catalysts are required with high activity, preferably at low-temperatures (To250 1C). Supported Pt and Au on ...
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Encapsulation of molecular hydrogen in ion-exchanged a zeolites at 1 atm
Efstathiou, Angelos M.; Borgstedt, E. v. R.; Suib, S. L.; Bennett, C. O. (1992)About 1.5 and 2.0 μmol/g of molecular HZ is encapsulated in the sodalite and supercages, respectively, of NaA zeolite at 1 atm H2 pressure and temperatures higher than 200°C. At 37°C and 1 atm Hz pressure, encapsulation ...
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Encapsulation of molecular hydrogen in zeolites at 1 atm
Efstathiou, Angelos M.; Suib, S. L.; Bennett, C. O. (1990)About 1 μmol/g of molecular H2 is encapsulated in the sodalite cages of NaX zeolite at 37°C and 1 bar H2 pressure. The removal of this hydrogen by diffusion can be studied by temperature programming between 40 and 150°C ...
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Enhancing the rate of ex situ mineral carbonation in dunites via ball milling
Rigopoulos, Ioannis; Vasiliades, Michalis A.; Ioannou, Ioannis; Efstathiou, Angelos M.; Godelitsas, A.; Kyratsi, Theodora (2016)The investigation of potential options for CO2 sequestration is of vital importance for alleviating the ongoing climate problem. This paper presents an efficient method for enhancing the ex situ carbonation of dunites. The ...
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Enthalpy and entropy of H2 Adsorption on Rh/Al2O3 measured by temperature-programmed desorption
Efstathiou, Angelos M.; Bennett, C. O. (1990)Temperature-programmed desorption spectroscopy under pseudo-equilibrium conditions has been used to obtain the coverage dependence of the heat and entropy of hydrogen adsorption for a 5-wt% Rh/Al2O3 catalyst. This method ...
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Hydrogen production by ethylene decomposition over Ni supported on novel carbon nanotubes and nanofibers
Savva, Petros G.; Olympiou, G. G.; Costa, Costas N.; Ryzhkov, V. A.; Efstathiou, Angelos M. (2005)Ethylene decomposition over Ni supported on novel carbon nanotubes (CNT) and nanofibers under consecutive reaction/regeneration cycles to form CO-free hydrogen and carbon deposits have been investigated. The present work ...
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Hydrogen Surface Concentration Effect on the Temperature-Programmed Hydrogenation of Adsorbed Carbonaceous Species on an Iron/Alumina Catalyst
Halafi, H.; Borgstedt, E.; Efstathiou, Angelos M.; Suib, S. L.; Bianchi, D. (1993)Temperature-programmed hydrogenation (TPH) of adsorbed carbonaceous species on metallic catalysts is a useful method to measure their numbers and reactivities. In the present paper it is shown that changes in the T.P.H ...
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In Situ Determination of Surface Carbon Species Formed on Rh/Al2O3 During CO/H2 Reaction by using Various Transient and Isotopic Methods
Efstathiou, Angelos M.; Chafik, T.; Bianchi, D.; Bennett, C. O. (1993)The evolution of surface species formed during the CO/H2 reaction at 220°C on a 1wt% Rh/Al2O3 catalyst was studied by transient methods using both mass spectrometry and FTIR. There is a very small amount of active carbon, ...