A fundamental kinetic model based upon the Hougen-Watson formalism was derived as a basis not only for a better understanding of the reaction behavior but also for the design and simulation of industrial reactors. Kinetic experiments were carried out using a commercial potassium-promoted iron catalyst in a tubular reactor under atmospheric pressure. Typical reaction conditions were temperature = 620oC, steam to ethylbenzene mole ratio = 11, and partial pressure of N2 diluent = 0.432 bar. Experimental data were obtained for different operating conditions, i.e., temperature, feed molar ratio of steam to ethylbenzene, styrene to ethylbenzene, and hydrogen to ethylbenzene and space time. The effluent of the reactor was analyzed on-line using two GCs. Kinetic experiments for the formation of minor by-products, i.e. phenylacetylene, α-methylstyrene, β-methylstyrene, etc, were conducted as well. The reaction conditions were: temperature = 600oC ~ 640oC, a molar ratio of steam to ethylbenzene = 6.5, and partial pressure of N2 diluent = 0.43 bar and 0.64 bar. The products were analyzed by off-line GC. The mathematical model developed for the ethylbenzene dehydrogenation consists of nonlinear simultaneous differential equations in multiple dependent variables. The parameters were estimated from the minimization of the multiresponse objective function which was performed by means of the Marquardt algorithm. All the estimated parameters satisfied the statistical tests and physicochemical criteria. The kinetic model yielded an excellent fit of the experimental data. The intrinsic kinetic parameters were used with the heterogeneous fixed bed reactor model which is explicitly accounting for the diffusional limitations inside the porous catalyst. Multi-bed industrial adiabatic reactors with axial flow and radial flow were simulated and the effect of the operating conditions on the reactor performance was investigated. The dynamic equilibrium coke content was calculated using detailed kinetic model for coke formation and gasification, which was coupled to the kinetic model for the main reactions. The calculation of the dynamic equilibrium coke content provided a crucial guideline for the selection of the steam to ethylbenzene ratio leading to optimum operating conditions.

Double Chooz est une expérience dédiée à la mesure de l'angle de mélange θ₁₃ caractérisant le phénomène d’oscillation des neutrinos. Elle consiste en l’installation de deux détecteurs identiques respectivement installés à 400 m et 1050 m des deux réacteurs à eau pressurisée de la centrale nucléaire de Chooz dans les Ardennes. Les réacteurs nucléaires sont en effet à l’origine d’un flux intense d’antineutrinos électroniques (de l’ordre de 10²¹ ⊽ₑ/s pour un réacteur de 1GWe)qui peut être détecté par réaction bêta inverse dans le liquide scintillant des détecteurs : ⊽ₑ + p −> e⁺ + n. Le paramètre θ₁₃ peut ensuite être déterminé en cherchant une réduction du nombre d’antineutrinos et une distorsion du flux mesuré dans le détecteur lointain par rapport au détecteur proche. La première phase de l’expérience pour laquelle uniquement le détecteur lointain prend des données a débuté en avril 2011. En l’absence du détecteur proche dont l’installation sera terminée en 2014, une prédiction du flux d’antineutrinos non oscillé attendu dans le détecteur lointain est nécessaire à la prédiction de θ₁₃ . Dans ce manuscrit, nous présentons le travail de simulation réalisé en vue de prédire les taux de fission des deux cœurs de Chooz à l’origine des antineutrinos émis par les réacteurs. Pour cela des simulations de cœur complet des réacteurs ont été développées à l’aide du code de simulation MCNP Utility for Reactor Evolution (MURE). Les résultats de ces simulations ont permis de déterminer les taux de fission et les erreurs systématiques associées durant les périodes de prise de données et d’aboutir à la première indication d’un angle θ₁₃ non-nul en novembre 2011. / The Double Chooz experiment is designed to search for a non-vanishing mixing angle θ₁₃ characterizing the ability of neutrinos to oscillate. It consists in two identical detectors located respectively at 400 m and 1050 m of the two pressurized water reactors of the Chooz nuclear plant in the French Ardennes. Indeed, nuclear reactor are huge electron antineutrino emitters (about 10²¹ ⊽ₑ/s for a 1GWe reactor). In Double Chooz, antineutrino sare detected by the inverse beta decay process in the liquid scintillator of the detectors : ⊽ₑ + p −> e⁺ + n. The θ₁₃ parameter can be investigated searching for ⊽ₑ disappearance and ⊽ₑ energy distortion in the far detector with respect to the near detector. The first phase of the experiment during which only the far detector is taking data has started in April 2011. In absence of far detector whose installation will be completed in 2014, a prediction of the non-oscillated antineutrino flux and spectrum shape expected in the far detector is mandatory to measure θ₁₃ . In this manuscript, we present the simulation work performed to predict the fission rates of both Chooz cores responsible for the reactor antineutrino flux. In this view, a complete core model has been developed with the MCNP Utility for Reactor Evolution (MURE) simulation code. The results of these simulations were used to determine the fission rates and associated systematic errors since the beginning of data taking and led to the first indication for a non-zero θ₁₃ mixing angle in November 2011.