5,392 research outputs found
Synthesis of Ni-Ru alloy nanoparticles and their high catalytic activity in dehydrogenation of ammonia borane
No full textWe report the synthesis and characterization of new NixRu1−x (x=0.56–0.74) alloy nanoparticles (NPs) and their catalytic activity for hydrogen release in the ammonia borane hydrolysis process. The alloy NPs were obtained by wet-chemistry method using a rapid lithium triethylborohydride reduction of Ni2+ and Ru3+ precursors in oleylamine. The nature of each alloy sample was fully characterized by TEM, XRD, energy dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS). We found that the as-prepared Ni–Ru alloy NPs exhibited exceptional catalytic activity for the ammonia borane hydrolysis reaction for hydrogen release. All Ni–Ru alloy NPs, and in particular the Ni0.74Ru0.26 sample, outperform the activity of similar size monometallic Ni and Ru NPs, and even of Ni@Ru core-shell NPs. The hydrolysis activation energy for the Ni0.74Ru0.26 alloy catalyst was measured to be approximately 37 kJ mol−1. This value is considerably lower than the values measured for monometallic Ni (≈70 kJ mol−1) and Ru NPs (≈49 kJ mol−1), and for Ni@Ru (≈44 kJ mol−1), and is also lower than the values of most noble-metal-containing bimetallic NPs reported in the literature. Thus, a remarkable improvement of catalytic activity of Ru in the dehydrogenation of ammonia borane was obtained by alloying Ru with a Ni, which is a relatively cheap metal
Structural and magnetic properties of Ru/Ni multilayers
No full textInternational audienceRu/Ni multilayers of different Ni thickness have been fabricated using magnetron sputtering. The structure of the multilayers has been determined by grazing incidence X-ray diffraction and X-ray reflectivity and their magnetic properties by magnetization and polarized neutron reflectivity measurements. The presence of Ru leads to the formation of a hexagonal Ni structure within interfacial layer ~1 nm above each Ru layer, while the rest of the Ni layer relaxes to the equilibrium fcc structure. The hcp Ni interfacial layer has a substantially increased cell volume is ferromagnetic with an atomic magnetic moment that increases with Ni layer thickness but remains lower than the value predicted from ab initio calculations
Structural and magnetic properties of Ru/Ni multilayers
No full textRu/Ni multilayers of different Ni thicknesses have been fabricated using magnetron sputtering. The structure of the multilayers has been determined by grazing incidence x-ray diffraction and x-ray reflectivity and their magnetic properties by magnetization and polarized neutron reflectivity measurements. The presence of Ru leads to the formation of a hexagonal Ni structure within an interfacial layer similar to 1 nm above each Ru layer, while the rest of the Ni layer relaxes to the equilibrium fcc structure. The hcp Ni interfacial layer has a substantially increased cell volume, and is ferromagnetic with an atomic magnetic moment that increases with Ni layer thickness but remains lower than the value predicted from ab initio calculations.Journal of Physics D-Applied Physic
Packed and monolithic reactors for the dry reforming of methane: Ni supported on g-Al2O3 promoted by Ru
No full textThe Dry reforming of methane (DRM) is as an efficient way for CH4 and CO2 valorisation because the produced syn-gas has an H2/CO ratio equal to that suitable for the synthesis of oxygenated hydrocarbons and synthetic fuels. The development of Ni (10 wt%) based structured and unstructured catalysts promoted by a small amount of Ru (0.5 wt%) has been investigated. Unstructured catalysts were prepared by wet impregnation method and a combination of wash coating-wet impregnation methods was used for cordierite monoliths. Ru promoted catalyst (Ni-Ru) was remarkable active showing higher reactant conversions and H2/CO ratio compared with Ni catalyst. Ni-Ru monolith was initially much more active than monometallic Ni stating the positive effect of Ru on maintaining Ni reduced. Reaching steady state condition, Ni rapidly deactivated due to carbon formation, whereas Ni-Ru monolith remained stable confirming that Ru behaves as an efficient and cheap promoter of Ni for DRM
The application of trace element and isotopic analyses to the study of Celtic gold coins and their metal sources
No full textThe focus of this study were Celtic gold coins excavated from the Martberg, a Celtic oppidium and sanctuary, occupied in the first century B.C. by a Celtic tribe known as the Treveri. These coins and a number of associated coinages, were characterised in terms of their alloy compositions and their geochemical and isotopic signatures so as to answer archaeological and numismatic questions of coinage development and metal sources. This required the development of analytical methods involving; Electron Microprobe (EPMA), Laser Ablation-ICP-MS, solution Multicollector-ICPMS and LA-MC-ICP-MS. The alloy compositions (Au-Ag-Cu-Sn) were determined by EPMA on a small polished area on the edge of the coins. A large beam size, 50µm (diameter), was used to overcome the extreme heterogeneity of these alloys. These analyses were shown to be representative of the bulk composition of the coins. The metallurgical development of the coinages was defined and showed that the earlier coinages followed a debasement trend, which was superceded by a trend of increasing copper at the expense of sliver while gold compositions remained stable. This change occurred with the appearance of the inscribed "POTTINA" coinage, Scheers 30/V. Two typologically different coinages, Scheers 16 and 18 ("Armorican Types") were found to have markedly different compositions which do not fit into the trends described above. A Flan for a gold coin, which may indicate the presence of a mint at the Martberg, was found to have an identicle weight and composition as the Scheers 30/I coins, which preceeded the majority of the coins found at the Martberg in the coin development chronology. The trace element anaylses were made by Laser Ablation-ICPMS using an AridusTM desolvating nebuliser to introduce matrix matched solution standards to calibrate the measurements, which were then normalised to 100%. Quantitative results were obtained for the following elements: Sc, Ti, Cr, Mn, Co, Ni, Cu, Zn, Se, Ru, Rh, Pd, Ag, Sb, Te, W, Ir, Pt, Pb, Bi. The remaining elements remain problematic as they produced incorrect standardisations mainly due to chemical effects in solution such as adsorption onto the beaker walls or oxidation : V, Fe, Ga, Ge, As, Mo, Sn, Re, Os, Hg. Changes in the sources of Au, Ag and Cu were observed during the development of the coinages through the variation of trace elements, which correlate positively with the major components of the coin alloys. Changes in the Pt/Au ratios show that the Scheers 23 coins contain distinctly different gold from the later coinages and that the Scheers 18 gold source was also different. Te/Ag was used to show that the Sch.23 coins also contained different silver and some subgroups were observed in the Sch. 30/V coins. A major change in copper source is indicated by the sudden increase of Sb and Ni with the introduction of the Sch. 30/V coins (POTTINA), which can be linked to a similar change in copper observed in the contemporary silver coinage, Sch. 55 (with a ring). Lead isotopic analyses were made by solution- and Laser Ablation - MC-ICP-MS, The laser technique proved to be in good agreement with the solution analyses with precisions between 1 and 0.1%o (per mil). The development of the laser method opens the way for easy and virtually non-destructive Pb isotopic determinations of ancient gold coins. The results showed that Sch. 23 is very different from the following coinages, Sch. 16 and 18 are also different, forming their own group, and all the later "Eye" staters (Sch. 30/I-VI) lie on a mixing line controlled by the addition of copper from a Mediterranean source, probably Sardinia or Spain. An indication of gold and silver sources should be possible with further analyses of the Sch. 23 and Rainbow Cup gold coins and the Sch. 54 and 55 silver coinages. Copper Isotopic analyses were made by solution- and Laser Ablation - MC-ICP-MS. Both techniques require further development to produce more reproducible results. The results show that there appears to be a trend to more positive d Cu65 values for the later coinages and that the link between the copper used in the Sch. 30/V (POTTINA) coins and the silver Sch. 55 (with a ring) coins is also shown by similarly postive d Cu65 values. The full suite of analyses were also made on samples of gold from the region. They were mostly composed of "placer gold", alluvial gold found in rivers. It was found that when a study is restricted to a limited number of deposits or areas then it is possible to distinguish between deposits based on the concentration of those elements which are least affected by transport related alteration processes. These elements include; the PGE's, due to their refractory nature, and those elements which are usually present in high enough concentrations to remain relatively unaffected, eg: Cu, Pb and Sb. Due to the nature of the coin alloy it is not possible to link the gold used in the coins studied here with gold deposits, as the large amounts of Ag and Cu, added to the coin alloys, have masked the Au signature. However, further Pb isotopic analyses of gold deposits should prove useful in determining from which regions Celtic gold was derived.Ziel dieser Arbeit war die Charakterisierung keltischer Goldmünzen, die am Martberg, einem keltischen oppidum und Kultstätte, ausgegraben wurden; diese Fundstelle wurde im ersten Jahrhundert vor Christus vom keltischem Stamm der Treveri bewohnt. Die Münzen und mit ihnen assoziierte Münzfunde wurden im Hinblick auf ihre Legierungszusammensetzung, ihre geochemischen und ihre Isotopen-Signaturen untersucht, um archäologische und numismatische Fragen der Münzentwicklung und der Rohstoffquellen zu klären. Dies geschah unter Zuhilfenahme analytischer Methoden; im Genaueren sind die Elektronenstrahlmikrosonde (EPMA), Laser-Ablation (LA-) Inductively Coupled (IC)- Mass Spectrometry (MS), Lösungs-Multicollector (MC)-ICP-MS und LA-MC-ICPMS. Die Zusammensetzungen der Legierungen im System Gold-Silber-Kupfer-Zinn wurden durch EPMA an einer kleinen, planpolierten Stelle an den Rändern der Münzen durchgeführt. Durch Verwendung eines auf 50 µm aufgeweiteten Strahldurchmessers konnten räumlich gemittelte Analysen erstellt werden, die große Heterogenitäten der Proben kompensieren, und mit Bulk-Analysen der Münzen übereinstimmen. Die metallurgische Entwicklung der Münzen konnte so erkannt werden; bei späteren Prägungen wurde zunächst der Goldanteil zugunsten eines erhöhten, festen Silber/Kupferanteils abgesenkt. Im Anschluss hieran gefertigte Prägungen zeigen erhöhte Kupfer/Silber-Verhältnisse bei konstantem Goldanteil. Dieser Wechsel ereignete sich mit dem Aufkommen der beschrifteten "Pottina"-Münzen, Scheers 30/V. Zwei typologisch unterschiedliche Münzgruppen, Scheers 16 und 18 ("Armorica"-Typ) fallen aus dem beschriebenen Trend heraus. Auch ein Rohling einer Goldmünze wurde am Martberg entdeckt und deutet so auf eine mögliche Prägestätte an diesem Ort hin, zudem dieser das gleiche Gewicht und die gleiche chemische Zusammensetzung wie die Scheers 30/I-Münzen aufweist. Diese stellen in einer zeitlichen Abfolge die Vorläufer der Hauptfunde am Martberg dar. Die Spurenelemente wurden durch LA-ICP-MS mit einem Aridus (TM) Zerstäuber analysiert, der Matrix-angepasste Standardlösungen zur Kalibrierung der Messungen einbrachte. Im Anschluss wurden die Ergebnisse durch die EPMA-Analytik auf 100% normalisiert. Quantitativ wurden folgende Elemente bestimmt: Sc, Ti, Cr, Mn, Co, Ni, Cu, Zn, Se, Ru, Rh, Pd, Ag, Sb, Te, W, It, Pt, Pb, Bi Die weiterer analysierten Elemente waren aufgrund falscher Standardisierungen problematisch; was vor allem auf physikalisch-chemische Lösungseffekte wie Adsorption an Gefäßwänden und Oxidation multivalenter Kationen zurückzuführen ist. Ihre Liste umfaßt: V, Fe, Ga, Ge, As, Mo, Sn, Re, Os, Hg. Veränderungen der Gold-, Silber- und Kupferquellen im Laufe der Münzentwicklung wurden durch die Variation der Spurenelemente belegt, die mit den Hauptelementen der Münzlegierungen positiv korreliert sind. Ein Wandel des Platin/Gold-Verhältnisses zeigt, dass die Scheers 23 Münzen eine deutlich von späteren Prägungen verschiedene Goldquelle beinhalten, ebenso ist die Herkunft der Scheers 18 Münzen eine andere. Das Tellur/Silber-Verhältnis kann aufzeigen, dass bei den Scheers 23 Proben auch eine andere Silberquelle benutzt wurde; ähnliche Schlüsse können aus der graphischen Auswertung bei einigen Untergruppen der Scheers 30/V Münzen gefunden werden. Ein deutlicher Wechsel der Kupferlagerstätte ist durch den signifikanten Anstieg der Antimon- und Nickelgehalte bei den Scheers 30/V Münzen ("Pottina") aufgezeichnet; dieser stimmt mit ähnlichen Veränderungen der Kupferkomponente bei zeitgleichen Silbermünzen überein (Probe Scheers 44 (mit Ring)). Die Blei-Isotopie wurde durch Lösungs- und LA-MC-ICP-MS analysiert. Laser- und Lösungstechniken zeigen gute Übereinstimmung mit einer Präzision zwischen 0,1 und 10/00. Die erstmalige Entwicklung adäquater Protokolle zur Bestimmung der Blei-Isotopie mittels Laser-Ablation eröffnet einen einfachen und quasi zerstörungsfreien Weg zur Charakterisierung antiker Goldmünzen. Die Ergebnisse zeigen einen deutliche Unterschied zwischen Scheers 23 und späteren Münzprägungen. Ähnlich hierzu Scheers 16 und 18, die eine eigene Gruppe bilden, und alle "Eye-staters"-Münzen (Scheers 30/I-VI), die auf einem Mischbereich aufspannen, der durch die Zugabe von Kupfer aus einer mediterranen Quelle - Sardinien oder Spanien - erzeugt wird. Hinweise auf die Gold- und Silberlagerstätten sollten in Zukunft möglich sein, wenn die Scheers 23 und "Rainbow cup"-Münzen wie auch die Scheers 54 und 55 Silbermünzen genauer untersucht werden. Kupferisotopische Analysen wurden durch Lösungs- und LA- MC-ICP-MS durchgeführt. Beide Techniken verlangen der Weiterentwicklung, um reproduzierbarere Ergebnisse zu erhalten. Die bisherigen Resultate zeigen einen Trend der späteren Prägungen zu erhöhten d 65Cu-Werten. Die bereits erwähnte Verbindung zwischen Scheers 55 (mit Ring) und den Scheers 30/V (Pottina)- Prägungen wird durch ähnliche d 65Cu-Werte bestätigt. Alle erwähnten analytischen Techniken wurden auch verwandt, um Goldproben aus der Region zu untersuchen. Meist handelt es sich hierbei um Goldseifen, alluviale Vorkommen in Flüssen. Es konnte gezeigt werden, dass eine Studie einer limitierten Anzahl von Lagerstätten oder Gebieten eine Unterscheidung zulässt, wenn man die Elemente betrachtet, die bei transportbedingten Alterierungsprozessen am wenigsten verändert werden. Diese umfassen neben den refraktären und inerten Platingruppenelementen die Elemente, die in solch hoher Konzentration auftreten, dass Alterierung sie nur unwesentlich beeinflusst, d.h. Kupfer, Blei und Antimon. Aufgrund der genutzten Legierungen ist es jedoch nicht möglich, das Gold der Münzen mit dem der Lagerstätte zu korrelieren, da die großen Beimengungen von Silber und Kupfer die Goldsignatur überlagern. Mit weiteren blei-isotopischen Analysen der Goldlagerstätten könnten jedoch weitere Rückschlüsse auf die Herkunft des keltischen Goldes gezogen werden
Ni supported on γ-Al2O3 promoted by Ru for the dry reforming of methane in packed and monolithic reactors
No full textDry reforming (DRM) is an efficient way for CH4 and CO2 valorization because the produced syn-gas has an H2/
CO ratio equal to that suitable for the synthesis of oxygenated hydrocarbons and synthetic fuels. The development
of Ni (10 wt%) based structured and unstructured catalysts promoted by a small amount of Ru (0.5 wt%)
for DRM has been investigated. Unstructured catalysts were prepared by the wet impregnation method and a combination
of wash coating-wet impregnation methods was used for cordierite monoliths. Samples were characterized
by XRD, BET, H2-TPR, TEM, FE-SEM, XPS techniques, and the catalytic activity for DRM was evaluated in the
temperature range 600–800 °C. The catalyst stability was followed at 800 °C during the time on stream. Ru promoted
catalyst (Ni-Ru) was remarkable active and stable whereas Ni catalyst deactivated due to the formation of Ni2+-
containing inactive phases. Ni-Ru monolith was initially much more active than monometallic Ni stating the positive
effect of Ru on maintaining Ni reduced. Reaching steady-state condition, Ni rapidly deactivated due to carbon
formation, whereas Ni-Ru monolith remained stable confirming that Ru behaves as an efficient and cheap promoter
of Ni for DRM
Ausscheidung topologisch dichtest gepackter Phasen in Ni-Basis Superlegierungen – der Einfluss von Re und Ru
No full textThe high-temperature strength of Ni-base superalloys may be strongly improved by alloying with Re. On the other hand, addition of Re has a negative influence on the long-term high temperature stability – it leads to precipitation of topologically close packed phases. These phases, in turn, are detrimental for the high-temperature strength of Ni base superalloys. Their precipitation process may be suppressed by alloying with Ru. However, although this finding is known since almost three decades, the mechanism of positive influence of Ru is not clarified, disabling the effective alloy design.
A new insight into the Re- and Ru effect on the precipitation of topologically close packed phases is described in this work. For this purpose six experimental Ni-base superalloys of second, third and fourth generation have been investigated. The results are focused on the scale-bridging characterization of the microstructure in the initial state, as well as after precipitation of topologically close packed phases. Modern techniques of materials characterization, like electron probe microanalysis, transmission and scanning electron microscopy, focused ion beam and three dimensional atom probe tomography are complemented with CALPHAD calculations to draw conclusions about Re and Ru influence on the precipitation of topologically close packed phases.
The quantitative analysis of the microstructure confirms that Re promotes while Ru inhibits precipitation of topologically close packed phases. Such effects of both elements are primarily related to thermodynamics – Re and Ru influence the driving force for precipitation. The results confirm that topologically close packed phases undergo sequential phase transformations. Physical phenomena controlling this behavior are considered and the respective conclusions are drawn.
The results of the current work show limitations at the commercially available databases for predicting phase transformations in Ni base superalloys, which are focused on the equilibrium stage of precipitation. The results presented in this work show that precipitation of topologically close packed phases has to be considered with respect to kinetics as well. They shed also some light into the understanding of TCP phase precipitation process under strain assisted service conditions.Die Hochtemperaturfestigkeit von Ni-Basis Superlegierungen kann durch Zugabe des Elementes Re signifikant verbessert werden. Re hat aber auch einen negativen Einfluss auf der Hochtemperaturphasenstabilität – es führt zur Ausscheidung spröder topologisch dichtest gepackter (TCP - engl. topologically close packed) Phasen. Diese Phasen sind kontraproduktiv für die mechanischen Eigenschaften. Eine Möglichkeit die Ausscheidung dieser spröden Phasen zu hemmen ist die Zugabe des Elementes Ru. Obwohl diese Entdeckung seit fast drei Jahrzehnte bekannt ist, ist der Mechanismus des positiven Einflusses von Element Ru nicht geklärt, was eine effektive Auslegung der Materialien verhindert.
Diese Arbeit stellt einen innovativen Ansatz zur Erklärung des Einflusses der Elemente Re und Ru auf die Ausscheidung der topologisch dichtest gepackten Phasen dar. Um das Ziel zu erreichen, sind sechs experimentelle Ni-Basis Superlegierungen der zweiten, dritten und vierten Generation untersucht worden. Die Ergebnisse sind auf eine skalenübergreifende Beschreibung des Gefüges im Ausgangzustand sowie nach der Ausscheidung der topologisch dichtest gepackten Phasen konzentriert. Moderne Untersuchungsmethoden wie Elektronenstrahlmikrosonde, Raster- und Transmissionselektronenmikroskopie, Tomographie mittels Ionenfeinstrahlanlage und dreidimensionaler Atomsonde zusammen mit thermodynamischen Berechnungen sind angewendet worden, um die Schlussfolgerungen bezüglich des Einfluss der Elemente Re und Ru auf die Ausscheidung der topologisch dichtest gepackten Phasen zu ziehen.
Die quantitative Analyse des Gefüges beweist, dass die Tendenz die topologisch dichtest gepackten Phasen auszuscheiden durch das Element Re erhöht- und durch das Element Ru herabgesetzt ist. Der Einfluss der beiden Elemente resultiert aus thermodynamischen Effekten – Re und Ru beeinflussen die Triebkraft der Ausscheidung. Weiterhin wurde bewiesen, dass sich die topologisch dichtest gepackte Phasen in einer Sequenz ausscheiden. Die entsprechenden physikalischen Phänomene sind betrachtet und die Schlussfolgerungen gezogen worden.
Die Ergebnisse dieser Arbeit zeigen, dass die Kinetik der Sprödphasenbildung eine große Rolle spielt und zurzeit eine Vorhersage der Ausscheidung topologisch dichtest gepackter Phasen sehr schwierig ist. Kommerzielle thermodynamische Datenbanken sind nicht in der Lage, die Tendenzen korrekt abzubilden und berechnen zudem ausschließlich Gleichgewichtsphasenanteile und –zusammensetzungen
The Structure and Stability of High Temperature Intermetallic Phases for Application within Coating Systems
No full textThe reduction of noise and emissions is becoming increasingly important in civil aircraft jet
engines as well as requirements for reduced fuel consumption and improved efficiency. This
has resulted in the drive towards increasing turbine entry temperatures and the development
of thermal barrier coatings (TBCs). Due to the effectiveness of the platinum-modified nickel
aluminides currently used as bond coat layers for Ni-based superalloy TBCs, higher
temperature ruthenium-containing bond coat layers are being examined as a possible low
cost alternative to platinum.
Rolls Royce have a patented process, whereby precious metal layers directly react with
single crystal substrate alloys to form an aluminium containing surface coating. The
aluminium is sourced from the single crystal alloy and the coating so formed has a +
structure, but contains other intermetallic phases due to the reaction between the coating and
the single crystal substrate. This bond coat layer acts as a diffusion barrier, which limits
interdiffusion between the coating and the substrate.
The aim of this research was to examine the stability of various phases within platinum and
ruthenium-containing multilayer systems formed during the above reaction process and to
determine the most stable intermetallics for inclusion in future coating systems. Foil samples
were manufactured using multilayer sputter coating methods and the exothermic formation
of these phases was examined using differential scanning calorimetry. The identification of
the phases formed was carried out using X-ray diffraction.
It was found that the interdiffusion between the initial multi-layers had been incomplete
during the samples heat treatment, and so more intermetallic phases formed in some samples
than aimed for. Hence, from the large number of samples studied it was shown that, as a
result of kinetic factors, the reaction onset (or trigger) temperature was not related to the
enthalpy of the intermetallic phases formed or the sample compositions within a target phase
field.
For the β-phase (NiAl) type intermetallic systems, the samples that produced the highest
enthalpy values (i.e. the most stable intermetallic compounds) were those with the nominal
compositions (in atomic %) of; ‘47Ni53Al’, ‘48Ni6Pt46Al’ and ‘51Ni7Ru42Al’.
For the γ΄-phase (Ni3Al) type intermetallic systems, the highest enthalpy values were from
samples with nominal compositions of ‘60Ni16Pt24Al’ and ‘74Ni5Ru24Al
Hydrogen production from sodium borohydride on a Ni-Ru catalyst : an electrochemical study
No full textPrevious work by the authors has demonstrated a high rate and high yield hydrolysis of sodium borohydride, in the presence of a Ni-Ru catalyst synthesized by wet chemistry. The catalyst has been fully characterized and utilized more than 300 times exhibiting high stability and durability. In this work, results of an electrochemical study are reported using the powder catalyst supported on a Ni foam in order to measure the open circuit potential during hydrogen production and to study the reaction using voltammetry and ac impedance. Production rates were as high as 10 Lmin-1gcat -1 at 65ºC. Electrochemical studies indicated that the hydrogen evolution mechanism corresponds to a Volmer- Heyrovsky type, suggested by a Tafel slope of 117 mVdec-1. Tafel region potentials are in agreement with values found for hydrolysis at the open circuit. The Langmuir-Hinshelwood mechanism explains the hydrolysis of sodium borohydride using a Ni-Ru catalyst. The role of Ni and Ru is briefly discussed
CO2 hydrogenation over Ru hydrotalcite-derived catalysts
No full textThe hydrogenation of CO2 over Ru catalysts is structure sensitive, the selectivity of the process can be driven either to the production of CH4 or CO depending on Ru particles and support features. Herein, Ru-based MgAl-HT (HT=hydrotalcite) derived catalysts with different Ru loadings (0.5, 1.0 and 2.0 wt%) and promoted with La3+ were prepared, characterized, and tested for CO2 methanation at high Gas Hourly Space Velocity values (480 L/gcat h) feeding a CO2/H2/N2 = 1/4/1 v/v mixture. The MgAlOx mixed oxide obtained after calcination at 600 °C and reduction provided weak, medium and mainly strong basic sites, able to activate the CO2 molecule, and hosted very small Ru nanoparticles (1–3 nm). However, the catalysts displayed a low activity in the low temperature range and a poor selectivity to CH4. The addition of La3+, despite contributing to the basicity, did not have any significant effect on performance. In a comparison between Ru- and Ni-HT-derived catalysts, tested under similar reaction conditions, Ni largely overperformed Ru
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