Hydrotreating of Vacuum Gas Oil on NiW/Al2O3 Catalysts Prepared with the Use of Chelating Agents

Tailoring morphology of hierarchical catalysts for tuning pore diffusion behaviour: a rational guideline exploiting bench-top pulsed-field gradient (PFG) nuclear magnetic resonance (NMR)

“…57 In the larger pore size samples, there is a much higher concentration of bulk liquid diffusing in the pore volume as opposed to that at the surface, and therefore, surface interactions will have a lower impact on the diffusivity. Intriguingly, water confined within the pores of Al 2 O 3 (1)-Al 2 O 3 (7) show lower values of interaction parameter than the respective tortuosity values obtained using n-octane indicating an 'enhanced' diffusivity of water relative to n-octane confined within the same network of pores, a property that has been previously detailed for various polyols confined within TiO 2 , SiO 2 and γ-Al 2 O 3 carriers. 49,58 This property is attributed to the disruption of the extensive hydrogen bonding networks between polyol molecules by the porous medium and recent work has confirmed this as well as demonstrating the importance of pore saturation to measuring accurate values of diffusivity in similar systems.…”

“…5 For analogous downstream processes, such as heavy vacuum gas oil or resid hydrotreating, larger pores (ca. 7-13 nm) 6,7 are required to allow diffusion and access of larger molecules to the catalyst active sites. Conversely, certain highly selective processes such as the partial epoxidation of ethylene to ethylene oxide 8,9 and the selective oxidation or selective hydrogenation of acetylene 10 require catalysts with large pores and low surface areas.…”