Influence of the Ageing and Drying Steps of a CoMoP/γ‐Al2O3 Catalyst onto the Multi‐Scale Molybdenum Active Phase Organization

Abstract

AbstractTo study the influence of ageing and drying steps onto the multiscale Mo active phase arrangement (i. e. MoS2 slabs and slab aggregates), a series of highly loaded CoMoP/γ‐Al2O3 catalysts aged, unaged, dried or freeze‐dried were prepared and tested in toluene hydrogenation. Electron Probe Micro Analyses (EPMA) and Anomalous Small Angle X‐Ray Scattering (ASAXS) permit to highlight the influence of each preparation steps. A growth of Mo entities occurs during ageing along with metal diffusion inside the support and leads to longer slabs. The same occurs during drying with metal redistribution due to solvent evaporation. Concomitantly, a fragmentation of slab aggregates takes place and leads to numerous small slabs aggregates. Slab length and aggregates amount were found to drive the catalytic activity, which translates the relationship between activity, number of active sites and their accessibility. Conversely, macroscopic metal distribution into the extrudates appears to have no impact on the catalytic performance.