Surface Chemistry on Small Ruthenium Nanoparticles: Evidence for Site Selective Reactions and Influence of Ligands

被引:44
作者
Novio, Fernando [1 ]
Monahan, Daniele [1 ]
Coppel, Yannick [1 ]
Antorrena, Guillermo [2 ]
Lecante, Pierre [3 ]
Philippot, Karine [1 ]
Chaudret, Bruno [4 ]
机构
[1] UPR8241 CNRS, Lab Chim Coordinat, F-31077 Toulouse, France
[2] Univ Zaragoza, INA, Dept Lab Microscopias Avanzadas LMA, Zaragoza 50018, Spain
[3] Ctr Elaborat Mat & Etud Struct CNRS, F-31055 Toulouse, France
[4] Inst Natl Sci Appl, UMR INSA CNRS UPS 5215, Lab Phys & Chim Nanoobjets, F-31077 Toulouse, France
关键词
catalysis; nanoparticles; ruthenium; solid-state reactions; surface chemistry; PROMISING CATALYTIC-SYSTEMS; ELECTRON-BEAM LITHOGRAPHY; CO OXIDATION; CARBON-MONOXIDE; PLATINUM NANOPARTICLES; ETHYLENE HYDROGENATION; SUPPORTED RUTHENIUM; HETEROGENEOUS CATALYSTS; ATOMIC-SCALE; STEADY-STATE;
D O I
10.1002/chem.201303935
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
The reactivity of two classes of ruthenium nanoparticles (Ru NPs) of small size, either sterically stabilized by a polymer (polyvinylpyrrolidone, PVP) or electronically stabilized by a ligand (bisdiphenylphosphinobutane, dppb) was tested towards standard reactions, namely CO oxidation, CO2 reduction and styrene hydrogenation. The aim of the work was to identify the sites of reactivity on the nanoparticles and to study how the presence of ancillary ligands can influence the course of these catalytic reactions by using NMR and IR spectroscopies. It was found that CO oxidation proceeds at room temperature (RT) on Ru NPs but that the system deactivates rapidly in the absence of ligands because of the formation of RuO2. In the presence of ligands, the reaction involves exclusively the bridging CO groups and no bulk oxidation is observed at RT under catalytic conditions. The reverse reaction, CO2 reduction, is achieved at 120 degrees C in the presence of H-2 and leads to CO, which coordinates exclusively in a bridging mode, hence evidencing the competition between hydrides and CO for coordination on Ru NPs. The effect of ligands localized on the surface is also evidenced in catalytic reactions. Thus, styrene is slowly hydrogenated at RT by the two systems Ru/PVP and Ru/dppb, first into ethylbenzene and then into ethylcyclohexane. Selectively poisoning the nanoparticles with bridging CO groups leads to catalysts that are only able to reduce the vinyl group of styrene whereas a full poisoning with both terminal and bridging CO groups leads to inactive catalysts. These results are interpreted in terms of location of the ligands on the particles surface, and evidence site selectivity for both CO oxidation and arene hydrogenation.
引用
收藏
页码:1287 / 1297
页数:11
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