Palladium nanoparticles stabilized by chitosan/PAAS nanofibers: A highly stable catalyst for Heck reaction

Abstract

Palladium chloride doped chitosan composite nanofibers were prepared by electrospinning with sodium polyacrylate (PAAS) as the co‐spinning agent. The composite nanofibers are subsequently treated at elevated temperature to improve their solvent resistance. The Pd (II) cations inside the composite nanofibers were reduced into uniform palladium nanoparticles (Pd NPs) with mean diameter of ~4.93 nm. These Pd NPs inside the chitosan composite nanofibers exhibited excellent catalytic activity for Heck reactions of aromatic iodides with alkenes with yields over 85%. Moreover, due to the fibrous structure, this novel fibrous palladium catalyst could be readily recovered by simple filtration and reused for 18 times without loss of initial catalytic activity. It was found that the reactants could readily diffuse from the reaction solution to the active Pd NPs inside the nanofibers and the products could departure from composite fibers into the reaction solution, while the Pd NPs were tightly restricted inside the chitosan composite nanofibers.

Ultrafine palladium nanoparticles confined in polydopamine functionalized chlorinated poly(vinyl chloride) nanofibers for Heck reaction

“…Electrospinning is a unique method to fabricate continuous nanofibers with diameters ranging from tens of nanometers to several micrometers from polymer solution or melt and these novel nanofibers holds great potential applications in catalysis, filtration, and so on 20–22 . In our previous study, 23,24 we have demonstrated that these nanofibers are ideal supporting matrices to encapsulate catalytic metal nanoparticles as active and reusable heterogeneous catalysts. Due to the ultrathin fibers, the reactants can easily diffuse into the interior of fiber to reach transition metal active species inside the nanofibers and the products can back diffuse into reaction solution.…”

Stabilization of palladium nanoparticles inside chitosan derived N‐doped carbon nanofibers for Heck reaction

“…30,31 As a result, the chitosan solution was rapidly turned into fixed gel after addition of Pd 2+ cations. In our previous study, 32 we have successfully prepared the Pd 2+ /chitosan homogeneous solution by addition of trifluoroacetic acid. Then, with PAAS as the co-spinning agent, uniform palladium encapsulated chitosan composite nanofibers were prepared by electrospinning (Figure 1a).…”

Sulfonated and cross‐linked polystyrene ultrafine fibers for the esterification of palmitic acid for biodiesel production

“…As the phenyl groups inside the fibers were sulfonated by H 2 SO 4 , the free volume holes should have provided the place for the diffusion of reactants and reaction of crosslinking and sulfonation (Table 2). 30,31 Thus, the free volumes of polystyrene fiber mat and PS-SA-SO 3 H were analyzed by PALS, which was an efficient and sensitive technique to assess the size and concentration of free volumes. 32,33 As shown in Table 2, the crosslinking of polystyrene molecules inside the fibers would reduce the size and concentration of free volume holes.…”