Unraveling Molecular Fingerprints of Catalytic Sulfur Poisoning at the Nanometer Scale with Near-Field Infrared Spectroscopy

Abstract

Fundamental understanding of catalytic deactivation phenomena such as sulfur poisoning occurring on metal/metal-oxide interfaces is essential for the development of high-performance heterogeneous catalysts with extended lifetimes. Unambiguous identification of catalytic poisoning species requires experimental methods simultaneously delivering accurate information regarding adsorption sites and adsorption geometries of adsorbates with nanometer-scale spatial resolution, as well as their detailed chemical structure and surface functional groups. However, to date, it has not been possible to study catalytic sulfur poisoning of metal/metal-oxide interfaces at the nanometer scale without sacrificing chemical definition. Here, we demonstrate that near-field nano-infrared spectroscopy can effectively identify the chemical nature, adsorption sites, and adsorption geometries of sulfur-based catalytic poisons on a Pd­(nanodisk)/Al2O3 (thin-film) planar model catalyst surface at the nanometer scale. The current results reveal striking variations in the nature of sulfate species from one nanoparticle to another, vast alterations of sulfur poisoning on a single Pd nanoparticle as well as at the assortment of sulfate species at the active metal–metal-oxide support interfacial sites. These findings provide critical molecular-level insights crucial for the development of long-lifetime precious metal catalysts resistant toward deactivation by sulfur.

Ultrasmall Pd Clusters in FER Zeolite Alleviate CO Poisoning for Effective Low-Temperature Carbon Monoxide Oxidation

“…Pd/zeolites are enigmatic model systems with unusual chemistry and relevance in the industry. , Entrapped metal ions or clusters with steric constraints by the zeolite structure carry strong potential for various catalytic reactions. , The unusual state of the “naked” di/polyvalent metal ions in zeolites has recently been identified, providing a framework for understanding high coordinative unsaturation and reactivity. − These cations can be reduced to metallic Pd or Pt under certain reductive conditions, leading to rich chemistry and a smear of species present both in the micropores (smaller species) and outside zeolitic micropores (nanoparticles). − These metals are typically used for oxidative reactions of carbon monoxide, nitric oxide, and hydrocarbons. Carbon monoxide (CO) is a highly toxic pollutant gas that is produced by incomplete combustion of fossil fuels and is a major contributor to the worsening air quality.…”

“…Carbon monoxide (CO) is a highly toxic pollutant gas that is produced by incomplete combustion of fossil fuels and is a major contributor to the worsening air quality. Palladium (Pd) catalysts have been used for the oxidation of CO in various industrial applications due to their high activity. − However, the use of Pd catalysts can be expensive and may also suffer from issues such as deactivation and poisoning . It is well known about Pd nanoparticles that once CO adsorbs on them, O 2 dissociation sites are blocked (due to a higher affinity of CO for Pd) and there is no activity in CO oxidation at low temperature. , Only when CO desorption begins to occur do the nanoparticles start catalyzing CO oxidation.…”

User-friendly and ultra-stable all-inclusive gold tablets for cysteamine detection

“…Based on the abovementioned facts, the concentrations and ratios of cysteamine have a signicant impact on the quantity of oxTMB in the system. As such, different ratios (25,50,75, and 100 mL) of 200 mM cysteamine were employed to assess the inhibition of the catalytic activity of the pAuNP-Tablet. It was observed that the maximum inhibition was achieved using 100 mL of cysteamine.…”

Plasma Cleaning of Cationic Surfactants from Pd Nanoparticle Surfaces: Implications for Hydrogen Sorption

“…It is therefore clear that the state of the surface plays a critical role when defining the barriers of the rate limiting step, which on a clean Pd surface for hydrogen absorption is the step from the surface to the first subsurface site and associative desorption of H 2 from the surface for the reverse process . However, it has also been shown that surface contaminants such as carbon monoxide (CO) − and sulfuric or sulfidic compounds (e.g., SO 2 and H 2 S), − as well as surfactant molecules used for colloidal synthesis of Pd nanocrystals , distinctly affect the rate of hydrogen sorption and the corresponding energetics. , At the same time, surface contamination is unavoidable upon exposure to ambient conditions or in colloidal Pd nanoparticle synthesis due to the multiple key roles of surfactants/capping agents, such as solubilizing the initial reagents, directing shape-selected particle growth, and preventing nanoparticle aggregation in suspension …”