Applications of high-resolution scanning probe microscopy in hydroprocessing catalysis studies

Abstract

Scanning probe microscopy offers real space atomic and nanoscale imaging of surfaces and supported nanoparticles, and these techniques are used in a planar catalyst model system context to analyze important atomic-scale aspects of nanoparticle structure, particle edges, defects, vacancies and to image the resulting interaction of individual reactants with the active surfaces. Here we review applications of high-resolution scanning probe microscopy to hydroprocessing catalysis, to demonstrate how these atom-resolved imaging techniques have recently advanced to become tools that elucidate the catalytically active edge structures of metal sulfide hydrotreating catalyst, resolve the intramolecular structure of complex hydrocarbons, and provide atomic-scale information on the mechanisms in which heteroatom-bearing hydrocarbons interact with a catalyst particle. This mini-review addresses the advantages of scanning tunneling microscopy for studies of planar model systems relevant for hydroprocessing catalysis, including the emerging use of near-ambient pressure (operando) scanning tunneling microscopy together with examples of the use of low-temperature molecular imaging with non-contact atomic force microscopy.