Impact of the Spatial Distribution of Active Material on Bifunctional Hydrocracking
Juan I. Mirena, Joris Thybaut, Guy Marin, Johan A. Martens, Vladimir Galvita
Abstract
Bifunctional catalysts are the preferred choice for hydrocracking processes. Ideal hydrocracking performance is defined by quasi-instantaneous (de)hydrogenation reactions over the metal sites and limited acid catalyzed side reactions, particularly the secondary cracking of desired products. Although their performance is heavily determined by the balance in activity between metal and acid sites, the spatial arrangement between both functions also holds a significant influence. Distance represents the simplest measure of the spatial distribution of active material. Various authors have explored the influence of the distance between sites, challenging the assumption that a minimal separation is necessary for ideal hydrocracking. Experimental evidence shows the important role of diffusion in the discussion of an intimacy criterion. The balance between site dispersion and mass transport properties within the porous catalyst can serve as a guideline in the tuning or design of ideal bifunctional catalysts.