Le programme de transport supersonique concorde : de l’innovation à la patrimonialisation

Depuis le XVIIIe siècle, l’histoire de l’aéronautique a été bâtie sur des exploits humains et des défis technologiques. L’une des aventures les plus marquantes de l’aviation est celle du transport supersonique (TSS) Concorde. De sa conception dans les années 1950 à la fin de son exploitation en 2003, l’avion a été à l’avant-garde de technologies appliquées par la suite aux autres gammes d’avions, permettant à l’industrie aéronautique européenne de devenir l’une des premières au monde. Cependant, des faiblesses structurelles comme le bruit des moteurs et une grande consommation en carburant, combinées à des conditions économiques et environnementales défavorables, ont contribué à sa mise en échec commercial. Et c’est là tout le paradoxe de Concorde. L’avion de tous les superlatifs, le plus beau, le plus rapide, le plus avancé, le plus performant, cet avion véritablement mythique et l’un des plus adulés de l’histoire de l’aéronautique, est aussi l’un des avions qui aura subi le plus de rejet.Since the 18th century, the history of aeronautics was built on human exploits and technological challenges. One of the most outstanding adventures of aviation is that of Supersonic Transport (TSS) Concorde. From its conception in the 1950’s to the end of its exploitation in 2003, the plane was with the avant-garde of technologies. They had been thereafter applied to the other ranges of planes, making the European aircraft industry able to become one of the first in the world. However, structural weaknesses like the noise of the engines and a high fuel consumption, combined with unfavourable economic and environmental conditions, contributed to its commercial failure. And it is there all the paradox of the Concorde. The plane of all superlatives, most beautiful, fastest, most advanced, most powerful, this truly mythical plane and one of the most adulated in the history of aeronautics, is also one of the planes which will have undergone the most rejection.Seit dem 18. Jahrhundert ist die Geschichte der Luftfahrt von wissenschaftlichen Errungenschaften und technischen Herausforderungen geprägt. Einer der herausragenden Meilensteine der Luftfahrt war die Entwicklung des Überschallflugzeugs „transport supersonique (TSS)“ mit Namen Concorde. Von seiner Konzipierung in den 1950er Jahren bis zum Ende seines Einsatzes 2003 stellte das Flugzeug eine technologische Avant-Garde dar, die großen Einfluss auf andere Flugzeuge haben sollte und es der europäischen Luftfahrtindustrie erlauben sollte, sich auf dem Weltmarkt zu etablieren. Strukturelle Schwächen wie der Motorenlärm und der große Kraftstoffverbrauch führten jedoch schließlich zusammen mit ungünstigen ökonomischen und ökologischen Faktoren zum kommerziellen Misserfolg des Überschallflugzeugs. Es offenbart sich darin das ganze Paradox der Concorde : Das Flugzeug der Superlative, das als schönstes, schnellstes, fortschrittlichstes und leistungsstärkstes gerühmt wurde, das als wahrer Mythos in die Geschichte der Luftfahrt einging, erwies sich gleichzeitig als dasjenige, das am meisten Ablehnung erfuhr

IR Spectroscopy Analysis and Kinetic Modeling Study for NH 3 Adsorption and Desorption on H- and Fe-BEA Catalysts

International audienceAmong different types of Fe-exchanged zeolites, Fe-BEA exhibits very promising surface properties for developing efficient urea or NH3-SCR systems. In this work, dedicated experimental and kinetic modeling studies were performed in order to elucidate mechanistic aspects related to NH3 storage and release on these catalysts. A series of NH3 adsorption and desorption experiments were performed over both H- and Fe-exchanged BEA zeolites, taking into account a broad range of operating conditions. Coupling FTIR spectroscopy, surface NH3 adspecies were characterized. NH3 gaseous concentration profiles were subsequently simulated by means of a detailed multisite kinetic model, being able to account for low-temperature adsorption phenomena. Finally, correlations between surface acidity and model sites were enabled by comparing IR spectroscopy and model predicted results, leading to the development of a phenomenological semidetailed, multisite kinetic modeling approach

Ammonium Nitrate Temperature-Programmed Decomposition on Fe–Zeolite Catalysts:Effect of Deposition Method

International audienceThe N2O formation during NOx selective catalytic reduction by NH3 is often attributed to NH4NO3 intermediate decomposition. Thermal decomposition of NH4NO3 has been extensively studied owing to the combination of its wide use as fertilizer and its dangerous properties. However, the decomposition of NH4NO3 in the presence of a catalyst has generated less attention. The decomposition of NH4NO3 may yield NxOy-type products such as NO, NO2, N2O, N2 as well as HNO3 and H2O. This work focuses on the emissions of N2O. The deposition of NH4NO3 onto a Fe–zeolite catalyst was carried out by dry impregnation, by using a dilute solution of NH4NO3, and by a mechanical mixture. In the absence of catalyst, the release of N2O strongly depends on the conditions of the experiment (static or dynamic). The presence of a catalyst and the method of mixing ammonium nitrate into it affects its decomposition. Nitrogen formation is much more significant for the impregnated sample. For the mechanically mixed sample, the ammonium nitrate is mainly decomposed into N2O and NO2. N2O from ammonia oxidation was also detected in the presence of a catalyst