Abstract
Different generations of poly(propylene imine) (Gn-PPI) terminated with N-containing 15-membered triolefinic macrocycle (GnM) (n = 2, 3, 4, 5) were prepared. The bimetallic nanoparticle catalysts GnM-(Ptx/Pd10−x) (x = 0, 3, 5, 7, 10) were prepared by the synchronous ligand-exchange reaction between GnM and the complexes of Pt(PPh3)4 and Pd(PPh3)4. The structure and catalytic properties of GnM-(Ptx/Pd10−x) were characterized via Fourier transform infrared spectroscopy, 1H nuclear magnetic resonance spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, energy-dispersive spectroscopy and inductively coupled plasma atomic emission spectroscopy. The novel bimetallic Pd–Pt nanoparticle catalysts stabilized by dendrimers (DSNs) present higher catalytic activities for the hydrogenation of dimeric acid (DA) than that of nitrile butadiene rubber (NBR). It can be concluded that bimetallic Pd–Pt DSNs possess alloying and synergistic electronic effects on account of the hydrogenation degree (HD) of DA and NBR. Furthermore, the HD of DA and NBR shows a remarkable decrease with the incremental generations (n) of GnM-(Pt3/Pd7) (n = 2, 3, 4, 5).
Highlights
For the past few years, bimetallic nanoparticles have attracted widespread attention among the academic community owing to their applications in fine chemicals, nanomedicine and petrochemical technology [1,2,3,4].As an oil chemical product with low toxicity, extensive sources and renewable materials, dimeric acid (DA) is widely applied to the synthesis of novel polymeric materials.Hydrogenated dimeric acid (HDA) is produced by unsaturated DA through catalytic hydrogenation reaction
Dendrimer-stabilized bimetallic nanoparticles were prepared via a simultaneous co-complexation method of complexes of Pt(PPh3)4 and Pd(PPh3)4 (Pt : Pd = 10 : 0, 7 : 3, 5 : 5, 3 : 7, 0 : 10 mol), and quantitative GnM which were dissolved in dimethylformamide (25 ml), and the mixture was refluxed with stirring for 7 days at 140°C under nitrogen
The novel mono-dispersed Pt–Pd bimetallic nanoparticles encapsulated by GnM (n = 2, 3, 4, 5) dendrimers have been prepared by the synchronous ligand-exchange reaction of Pt(PPh3)4 and Pd(PPh3)4 successfully
Summary
For the past few years, bimetallic nanoparticles have attracted widespread attention among the academic community owing to their applications in fine chemicals, nanomedicine and petrochemical technology [1,2,3,4]. To contrast the difference between the two types of catalysts, the former possesses higher catalytic activity and leads to higher degree of hydrogenation, which attracts extensive attention for the catalytic hydrogenation of NBR. Their high cost as well as difficult catalyst removal hinders their application in HNBR production. Extensive research and development work has been conducted on novel hydrogenation catalysts for NBR, aimed at obtaining high selectivity, efficient catalytic activity, cost-effectiveness and ease of removal [9]. In comparison to monometallic nanoparticles, bimetallic nanoparticles have unique properties, such as synergistic electric effect, high selectivity, efficient catalytic activity and cost-effectiveness [10,11,12,13]. The HD of DA and NBR shows a remarkable reduction with the incremental generations (n) of GnM-(Pt3/Pd7)
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