Abstract EN:

The genesis of the active phase in hydrotreating catalysts is deeply influenced by the nature of the support. However, a fine description of active phase-support interactions at the molecular level is still missing since the traditional support γ-Al2O3 exhibits ill-defined sorption sites. A surface-science approach in aqueous phase circumvented this limitation by using α-Al2O3 single crystals with four different orientations: C(0001), A(112 ̅0), M(101 ̅0), and R(11 ̅02) as surrogates to study the genesis of MoS2 exerting control over surface sites. Such approach revealed that properties of MoS2 were dictated by Mo-support interactions which are, in turn, determined by the nature of surface -OH. The present work aims to take a step further in closing the gap between model and industrial catalysts by incorporating cobalt, phosphorus and TEG in model catalyst formulation. Surface-sensitive techniques are used to expose such dependencies. It is shown that phosphorus interacts differently depending on support orientation, leading to a surface-dependent sulfidation. Conversely, it is shown that cobalt promotion of MoS2 is exclusively dependent on Mo sulfidation. At last, it is shown how omitting calcination and TEG incorporation reduces metal-support interactions leading to higher sulfidation. The catalytic activity of promoted catalysts is studied through a thiophene hydrodesulfurization reaction revealing that A(112 ̅0)-based catalysts display the highest activity. In that sense, intermediate metal-support interactions are key to achieve higher catalytic performance. These results could lead to a new generation of hydrotreating catalysts through control of support morphology.