Remote Control of Catalytic Sites by Spillover Species: A Chemical Reaction Engineering Approach∗

Hydrodesulfurization, Hydrodenitrogenation and Hydrodearomatization over CoMo/SAPO-11-Al₂O₃ Catalysts

“…Similar findings for NiMo supported SBA-15 catalysts in an investigation of HDS of DBT showed that citric acid addition resulted in better dispersion of Mo species using powder X-ray diffraction (XRD) and UV-vis diffuse reflectance spectroscopy (DRS) characterization 20) . Higher Mo 4 content as demonstrated by XPS also revealed that citric acid promoted Mo atom mobility and reduction from Mo 6 to Mo 4 . As a result, citric acid added catalysts show better CoMoS formation.…”

“…Therefore, a specific catalyst is needed for desulfurization and denitrogenation, and selective hydrogenation of bicyclic or tricyclic aromatic compounds to monocyclic aromatic compounds 1) . Several models for the structure of the active phase 2) 4) of cobalt promoted MoS2 catalysts have been proposed, but the CoMoS phase consisting of cobalt atoms on the edge of MoS2 slabs is widely accepted 5) 7) . The RimEdge model with two types of active sites, the Rim site and the Edge site, can explain the differences in the hydrogenation (HYD) and hydrodesulfurization (HDS) active sites 8) .…”

Aberration-corrected multipole Wien filter for energy-filtered x-ray photoemission electron microscopy

“…As examples, oxygen diffusion in mixed oxides causes high selectivity for oxidation of hydrocarbons, and hydrogen migration from metal particles affects the acidity of supports. [1][2][3] Another example is the hydrodesulfurization reaction on Ni 2 P / SiO 2 where partially formed Ni-S bond plays an important role in S-C bond scissions during the hydrodesulfurization. 4,5 The characterization of spatial inhomogeneity in heterogeneous catalysts is a key issue in understanding these catalytic reactions.…”

Optimal structure of bimetallic catalysts for the A+B2 reaction

“…The support may function as a reservoir of reactants which diffuse to the metal where they react (spillover effect) [4][5][6][7]. It is also possible that the metal has two (or more) facets with different adsorption characteristics; at reaction conditions in which one would be poisoned, the other might be reactive [6,8].…”