Synthesis and hydrogenation application of Pt–Pd bimetallic nanocatalysts stabilized by macrocycle-modified dendrimer

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).

Non-biodegradable polymeric waste pyrolysis for energy recovery

“…Therefore engineering catalysts at the nanoscale can specifically achieve the targeted high S/V. Nanosized catalysts display additional unique properties not present in the macroscale bulk catalyst materials [190,191,192,193,194], further contributing towards lower process energy consumption, longer catalyst lifecycle and enhanced ease in isolating and reusing the active nanocatalysts [108]. Nanocatalysis though regarded as "soluble heterogeneous" [195] or "semi-heterogeneous" [101] catalysis, may be considered as a distinct category which combines the beneficial aspects of exclusive high activity with attainment of near 100% selective reactions and excellent yield associated with homogeneous catalysis and tremendously eased product separation along with catalyst recovery related to heterogeneous catalysis [106,186,196].…”

Synthesis of polymer protected Pd–Ag/ZnO catalysts for phenylacetylene hydrogenation

“…However, in many cases, harsh conditions (high temperatures and pressures) are required. An alternative is the use of palladium catalysts, which can be very effective in hydrogenation of both triple and double carbon-carbon bonds [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16].…”

“…Bimetallic nanoparticles combine the properties of both composite metals, and, in some cases, demonstrate improved catalytic properties due to a synergistic effect [8][9][10][11][12][13][14][15][16]. Supported Pd-Ag catalysts increasingly attract attention, and are used in the hydrogenation of acetylene compounds because of their high selectivity to olefin compounds [17][18][19][20].…”