Sulphur Poisoning of Metals. “Model Experiments on Single Crystals”

Nanoclusters in Catalysis: A Comparison of CS2 Catalyst Poisoning of Polyoxoanion- and Tetrabutylammonium-Stabilized 40 ± 6 Å Rh(0) Nanoclusters to 5 Rh/Al2O3, Including an Analysis of the Literature Related to the CS2 to Metal Stoichiometry Issue

“…Overall, there is every reason to believe that CS 2 and other poisoning studies will become at least as important in nanocluster catalysis as they are in traditional heterogeneous catalysis. ,− The present studies are, however, just the start of the needed nanocluster poisoning studies…”

“…Even with preferred poisons such as CS 2 , one needs to appreciate that studies on single crystals and heterogeneous catalysts reveal that the poisoning of metal surfaces by S is complex with either steric (ensemble) 17a, or electronic (ligand) 17a,, effects often being discussed. Although steric effects are generally local and can be minimized with the use of “small” poisons such as H 2 S and CS 2 , electronic perturbations of the surface appear to be long-range in nature and have been used to explain poison/metal-atom stoichiometry ratios seen in studies of single crystals of anywhere from 1/1.5 to 1/20 (results that we will examine in more detail in the Discussion section; vide infra). , In addition to steric and electronic effects, poison studies are further complicated by possible poison-induced morphological changes in the catalyst, that can then alter its activity. 17a, Hence, as with any indirect method there is the issue of whether or not the method (in this case the poison) is “reporting, or causing, the news.” It is also important to appreciate that the catalyst poisoning literature makes it clear that poison-to-metal ratios are not absolute but, rather, depend upon the other ligands that are present, the reaction, the pressure, the temperature, and the other experimental conditions. − Nevertheless, despite the drawbacks in catalyst poisoning studies, catalysis is inherently a completely kinetic phenomenon so that catalyst poisoning kinetics are an essential component of any study that aspires to establish the true number of active sites or any property connected to this value such as the turnover frequency (TOF) or total turnovers (TTOs) …”

Strategies for Carbon and Sulfur Tolerant Solid Oxide Fuel Cell Materials, Incorporating Lessons from Heterogeneous Catalysis

“…These impurities, even at very low concentrations, are responsible for heterogeneous catalyst deactivation. Millions of dollars are lost in chemical and oil industries as a result of sulfur poisoning. , …”