from first principles PP-I-1

PP-III-33A Theoretical and Experimental Study of Nickel-Alumina Eggshell CatalystPreparation Process for Reforming ReactionsGoula M.A., Bereketidou O.A., Avraam D.G.Laboratory of Alternative Fuels and Environmental Catalysis (LAFEC)Pollution Control Technologies Department (PCT), School of Technological ApplicationsTechnological Educational Institute of Western Macedonia (TEIWM)Koila, 50100 Kozani, Greeceemail:mgoula@teikoz.grCatalytic reforming is a well-established industrial process for converting hydrocarbons intohydrogen or synthesis gas and has been extensively studied in recent decades. Among activecatalysts for reforming reactions, it has been reported that noble metals present high activity,however their limited availability and high cost promote the use of nickel catalysts due to the factthat this metal offers its redox properties and its lower cost, which makes it easily accessible. Toimprove the catalytic performance and minimize coking of the nickel catalyst, several conditionscan be modified, such as characteristics of the support, metal content, preparation method and theintroduction of promoters into the catalyst formulation [1]. Egg-shell catalysts are useful inprocesses where the reaction has a very high rate and the intraparticle diffusion becomes thelimiting step. For a positive order reaction (e.g. reforming reactions), in the absence of selectivityor poisoning considerations, an “egg shell” catalyst seems to be optimum [2]. In this study, Nisupported on alumina catalysts with core/shell structures, were prepared in different metalloadings (7 and 15wt % Ni) by a combination of the edf method [3] with the wet impregnationtechnique. The physicochemical properties of the final catalysts were determined by XRD, ICP-AES, TEM and SEM. Moreover, a theoretical model of the catalyst preparation process for nickelcatalysts supported on cylindrical γ–alumina extrudates, based on the Lee and Aris model, wasdeveloped. The model was validated against the experimental data concerning the radialdeposition profiles of Ni on γ-alumina cylindrical extrudates prepared by the edf-wet methodproposed by the authors. It can be concluded that there is a satisfactory theoretical prediction ofnickel species concentration profile for given experimental conditions, while the parameterspredicted by the model were discussed along with those derived from previous work according tothe literature.References:[1] O.A. Bereketidou and M.A. Goula, J. Catal. submitted for publication.[2] E. R. Becker and J. Wei, J. Catal. 46 (1977) 365-371.[3] N. Spanos and A. Lycourghiotis, J. Colloid Interface Sci., 171 (1995) 306.185