Influence of the electronic state of the metals in Fe–Pt/SiO2 catalysts on the performance of hydrogenation of phenylacetylene

Capture-bonding Super Assembly of Nanoscale Dispersed Bimetal on Uniform CeO2 Nanorod for the Toluene Oxidation

Elimination of VOCs by catalytic oxidation is an important technology. Here, a general synergistic capture-bonding superassembly strategy was proposed to obtain the nanoscale dispersed 5.8% PtFe₃ -CeO₂ catalyst, which showed a high toluene oxidation activity (T₁₀₀ =226 °C), excellent catalytic stability (125 h, >99.5%) and a good water resistance ability (70 h, >99.5%). Through the detailed XPS analysis, oxygen cycle experiment, hydrogen reduction experiment, and in-situ DRIFT experiment, we could deduce that PtFe₃ -CeO₂ had two reaction pathways. The surface adsorbed oxygen resulting from PtFe₃ nanoparticles played a dominant role, due to the fast cycling between the surface adsorbed oxygen and oxygen vacancy. In contrast, the lattice oxygen resulting from CeO₂ nanorods played an important role due to the relationship between the toluene oxidation activity and the metal-oxygen bonding energy. Furthermore, DFT simulation verified Pt sites were the dominant reaction active sites during this reaction.

Insights into the Interfacial Effects in Heterogeneous Metal Nanocatalysts toward Selective Hydrogenation

Heterogeneous metal catalysts are distinguished by their structure inhomogeneity and complexity. The chameleonic nature of heterogeneous metal catalysts have prevented us from deeply understanding their catalytic mechanisms at the molecular level and thus developing industrial catalysts with perfect catalytic selectivity toward desired products. This Perspective aims to summarize recent research advances in deciphering complicated interfacial effects in heterogeneous hydrogenation metal nanocatalysts toward the design of practical heterogeneous catalysts with clear catalytic mechanism and thus nearly perfect selectivity. The molecular insights on how the three key components (i.e., catalytic metal, support, and ligand modifier) of a heterogeneous metal nanocatalyst induce effective interfaces determining the hydrogenation activity and selectivity are provided. The interfaces influence not only the H₂ activation pathway but also the interaction of substrates to be hydrogenated with catalytic metal surface and thus the hydrogen transfer process. As for alloy nanocatalysts, together with the electronic and geometric ensemble effects, spillover hydrogenation occurring on catalytically "inert" metal by utilizing hydrogen atom spillover from active metal is highlighted. The metal-support interface effects are then discussed with emphasis on the molecular involvement of ligands located at the metal-support interface as well as cationic species from the support in hydrogenation. The mechanisms of how organic modifiers, with the ability to induce both 3D steric and electronic effects, on metal nanocatalysts manipulate the hydrogenation pathways are demonstrated. A brief summary is finally provided together with a perspective on the development of enzyme-like heterogeneous hydrogenation metal catalysts.

Unusual behavior of bimetallic nanoparticles in catalytic processes of hydrogenation and selective oxidation

Recent results obtained in studying mono- and bimetallic catalysts for selective hydrogenation of unsaturated carbonyl compounds, even unsaturated ones, acetylenic and nitro compounds as well as CO and bio-available alcohols oxidation are reviewed from the standpoint of the strong interaction between the metal nanoparticles, on the one hand, and two metals in the composition of bimetallic nanoparticles, on the other hand. Such interactions were demonstrated to result in partial positive or negative charging of metal nanoparticles, which, in turn, changes their adsorption and catalytic properties, especially with respect to the reactions involving hydrogen. Among the systems studied, Au–Pt, Au–Pd, Au–Cu, Au–Fe, Pt–WO x , Fe–Pd, Fe–Pt, Fe–Cu nanoparticles prepared by the redox procedure are considered to be most perspective in diverse catalytic applications because of the proper combination of the particle size and the electronic state of the metals.