Highly Efficient Nanocatalysts Supported on Hollow Polymer Nanospheres:  Synthesis, Characterization, and Applications

Abstract

Hollow polymer nanospheres were employed in the fabrication of noble metal-supported catalysts via a supercritical route. In this method, the metal precursors were first adsorbed on the polymer support in a supercritical CO 2 -ethanol solution, followed by H 2 reduction, generating metal (Pd, Rh, Pt)/polymer composites. The resultant Pd/polymer nanospheres were characterized by means of X-ray diffraction, scanning electron microscopy, transmission electron microscopy equipped with energy dispersive spectroscopy, and X-ray photoelectron spectroscopy analysis. It was indicated that the Pd nanoparticles with a size of about 5 nm were uniformly attached to the surface of the polymer spheres. The activities of the Pd/polymer composites for the allyl alcohol hydrogenation and Heck reaction were also investigated. The catalyst exhibited a high activity and stability in these two reactions.

Synthesis and property of polymer nanospheres with Pd/P4VP shells via surface RAFT polymerization

“…The oxidation form of Pd is possibly palladium oxide, which may result from the surface oxidation of palladium nanoparticles when they are exposed to air. A similar phenomenon was also reported by others [42,43].…”

“…The XPS spectrum of Pd 3d can be curve-fitted into two spin-orbit-split doublets, as illustrated in Figure 5d. The two peak components at the BEs [36,42]. The other set of peaks at 337.7 eV (Pd 3d 5/2 ) and 342.9 eV (Pd 3d 3/2 ) is ascribed to the Pd 2+ [38,43].…”

“…The increased oxidation form of Pd possibly results from the surface oxidation of palladium nanoparticles during the Heck reaction [42,43].…”

“…The surface of the nanoparticles becomes a little rough after being recycled four times, as shown in Figure 8f. During the reaction process, most of the leached Pd species can be adsorbed on the polymer support [42], so the catalyst remains good in activity and is stable after being recycled several times.…”

Hydrogen (H2) sensing and catalysis with organic-stabilized Pd and Pd alloy nanoparticles.

“…Catalytic selective hydrogenation of allyl alcohol to produce 1-propanol, which is a precursor in organic synthesis and the pharmaceutical industry, has been studied as a function of particle size and shape of Pd NPs coated with polymers, 134,135 biopolymers (collagen fiber), 136 surfactants, 35 or dendrimers 29,30,32,123,124,137,138 either in solution or immobilized on solid supports such as alumina, 35,134 composites, 32 silica, 139 and magnetic NP cores. [140][141][142] However, the transformation of allyl alcohol to carbonyl compounds (isomerization reaction) has not been widely explored using Pd NPs as catalysts.…”