Modelling of kinetic and transport effects in aldol hydrogenation over metal catalysts

Effect of Internal Diffusion in Supported Ionic Liquid Catalysts: Interaction with Kinetics

“…For a catalyst object with an arbitrary geometry, the mass balance for an infinitesimal volume element is written as where A denotes the outer surface of the object residing in the reference volume, F p is the density of the catalyst object, ∆V p is the volume element of the catalyst object, and n i stands for the amount of the compound in the reference volume. This equation (eq 14) can be rewritten 9 into where s denotes the shape factor of the object (s ) 0, 1, or 2 for slabs, infinite cylinders, and spheres, respectively). For nonideal particles the value of the shape factor is calculated from s + 1 ) (5/3 + (1 + R)R/L)/(1 + R); R ) 1/(3π) 0.5 -1/6.…”

“…For improved numerical accuracy, the concentration gradient at the surface was derived through integration of the concentration profile in the catalyst object, as discussed by Salmi et al…”

“…Importantly, internal mass-transfer (inside the catalytic material) as well as coupled diffusion and reaction that can have major influence on the performance of, especially, an industrial process is often not studied in detail, and consequently, misleading conclusions can be drawn about the limiting phenomena involved. The interaction of reaction and diffusion in porous catalysts has been experimentally studied and modeled by, e.g., Salmi et al and Toppinen et al , However, often the studies have been conducted on chemically relatively simple systems, except work by, e.g., Julcour et al and Aumo et al in which more complex hydrogenation systems were addressed and reaction-diffusion phenomena were quantitatively modeled.…”