270
example, Ponchel and co-workers have studied the preparation of carbon-supported
ruthenium catalysts for gas-phase hydrogenation reactions (Denicourt-Nowicki
et al. 2008; Wyrwalski et al. 2011). The idea was to take advantage of an efficient
anchoring of the metallic nanoparticles onto the carbon support via hydrophobic
interactions coming from the presence of the cyclodextrin. To validate the strategy,
a series of carbon-supported ruthenium nanocatalysts were prepared by the adsorption on a porous activated carbon of Ru nanoparticles preformed in aqueous solution by chemical reduction of RuCl 3 in the presence of RaMe-cyclodextrin (α, β,
and γ). Nitrogen adsorption measurements showed that the immobilization of the
RaMe-cyclodextrin-stabilized Ru nanoparticles deeply affected the textural properties of the porous carbon material. Moreover, thermogravimetric measurements
proved that the prepared catalysts were thermally stable up to 235 °C under both
inert and reducing atmospheres. Finally, the study of the dispersion and morphology
of the supported particles was carried out by transmission electron microscopy analysis. For instance, the transmission electron microscopy characterization of the
Ru-3-β-cyclodextrin/C sample showed that nanoparticles had a spherical shape with
an average diameter of 2.4 nm. The catalytic activity of the Ru nanoparticles was
evaluated in the hydrogenation of xylene isomers in gas phase at 85 °C. The catalytic results had clearly shown that the cyclodextrin-based Ru catalysts were more
efficient than the control Ru/C. Moreover, the catalytic activity depended on the
cyclodextrin size and initial cyclodextrin/Ru ratio. In terms of stereoselectivity, the
trans to cis ratio was improved in the presence of cyclodextrin-based catalysts and
thus whatever the substrate. These results can be explained by several factors such
as the dispersion of the active species through a promoting effect of the cyclodextrin
and the host-guest interactions occurring between the substrate and cyclodextrin,
which is adsorbed onto the nanoparticles.
The generation of materials from the incorporation of metal particles into polymer matrix received a growing interest due to applications in electrocatalysis such
as methanol oxidation (Chen et al. 2014) or dioxygen electroreduction (Gopalan
et al. 2006; Chen et al. 2015). For example, gold nanoparticles were stabilized by an
inclusion complex of cyclodextrin with 4-aminothiophenol. These nanoparticles
were then electrochemically deposited on glass electrode forming Au(0) nanoparticles and poly(aminothiophenol). A repairable catalytic system was considered on
the basis of pre-synthesized gold nanoparticles stabilized by thiolated-β-cyclodextrin
and porous nickel (PNi) containing azobenzene compounds to adsorb these metal
nanoparticles by the formation of an inclusion complex (Zhou et al. 2017). The high
specific surface area and connected porous structure of porous nickel provided a
good opportunity to achieve the multivalent interactions between β-cyclodextrin-Au
nanoparticles and PNi@IPTS-Azo. Additionally, the reactant solution could be catalyzed by flowing through the pores of the PNi@IPTS-Azo@β-CD-AuNPs. This
catalytic model showed a high efficiency close to 95%. Because of the reversible
multivalent host-guest interactions between thiolated β-cyclodextrin and azobenzene, the catalytic system could be regenerated by removing the deactivated Au
nanoparticles with UV light irradiation and recombining new ones through in situ
multivalent interactions. Because of the large specific surface area and connected
S. Noël et al.
example, Ponchel and co-workers have studied the preparation of carbon-supported
ruthenium catalysts for gas-phase hydrogenation reactions (Denicourt-Nowicki
et al. 2008; Wyrwalski et al. 2011). The idea was to take advantage of an efficient
anchoring of the metallic nanoparticles onto the carbon support via hydrophobic
interactions coming from the presence of the cyclodextrin. To validate the strategy,
a series of carbon-supported ruthenium nanocatalysts were prepared by the adsorption on a porous activated carbon of Ru nanoparticles preformed in aqueous solution by chemical reduction of RuCl 3 in the presence of RaMe-cyclodextrin (α, β,
and γ). Nitrogen adsorption measurements showed that the immobilization of the
RaMe-cyclodextrin-stabilized Ru nanoparticles deeply affected the textural properties of the porous carbon material. Moreover, thermogravimetric measurements
proved that the prepared catalysts were thermally stable up to 235 °C under both
inert and reducing atmospheres. Finally, the study of the dispersion and morphology
of the supported particles was carried out by transmission electron microscopy analysis. For instance, the transmission electron microscopy characterization of the
Ru-3-β-cyclodextrin/C sample showed that nanoparticles had a spherical shape with
an average diameter of 2.4 nm. The catalytic activity of the Ru nanoparticles was
evaluated in the hydrogenation of xylene isomers in gas phase at 85 °C. The catalytic results had clearly shown that the cyclodextrin-based Ru catalysts were more
efficient than the control Ru/C. Moreover, the catalytic activity depended on the
cyclodextrin size and initial cyclodextrin/Ru ratio. In terms of stereoselectivity, the
trans to cis ratio was improved in the presence of cyclodextrin-based catalysts and
thus whatever the substrate. These results can be explained by several factors such
as the dispersion of the active species through a promoting effect of the cyclodextrin
and the host-guest interactions occurring between the substrate and cyclodextrin,
which is adsorbed onto the nanoparticles.
The generation of materials from the incorporation of metal particles into polymer matrix received a growing interest due to applications in electrocatalysis such
as methanol oxidation (Chen et al. 2014) or dioxygen electroreduction (Gopalan
et al. 2006; Chen et al. 2015). For example, gold nanoparticles were stabilized by an
inclusion complex of cyclodextrin with 4-aminothiophenol. These nanoparticles
were then electrochemically deposited on glass electrode forming Au(0) nanoparticles and poly(aminothiophenol). A repairable catalytic system was considered on
the basis of pre-synthesized gold nanoparticles stabilized by thiolated-β-cyclodextrin
and porous nickel (PNi) containing azobenzene compounds to adsorb these metal
nanoparticles by the formation of an inclusion complex (Zhou et al. 2017). The high
specific surface area and connected porous structure of porous nickel provided a
good opportunity to achieve the multivalent interactions between β-cyclodextrin-Au
nanoparticles and PNi@IPTS-Azo. Additionally, the reactant solution could be catalyzed by flowing through the pores of the PNi@IPTS-Azo@β-CD-AuNPs. This
catalytic model showed a high efficiency close to 95%. Because of the reversible
multivalent host-guest interactions between thiolated β-cyclodextrin and azobenzene, the catalytic system could be regenerated by removing the deactivated Au
nanoparticles with UV light irradiation and recombining new ones through in situ
multivalent interactions. Because of the large specific surface area and connected
S. Noël et al.