Synthesis And Application Of Transition-metal Nanoparticles Stabilized By Quarternary Ammonium-based Ionic Liquid With Polyethylene Glycol Chain

Ru, Rh, Pd nanoparticles stabilized by the quarternary ammonium-based ionic liquids [CH3(OCH2CH2)nN+Et3][CH3SO3-](n=12,16,22; abbreviated as ILPEG55o, ILPEG750, ILPEG1000) with polyethylene glycol chain were synthesized and investigated as catalysts for hydrogenation, hydroformylation of olefins or Heck reaction in the thermoregulated ionic liquid and organic biphase system, composed of above-mentioned ionic liquids, toluene and n-heptane, which allows for not only a homogeneous reaction but also an easy biphasic separation.Thermoregulated ionic liquid and organic biphase systems with Ru, Rh, Pd nanoparticles were used for hydrogenation of olefins. The catalysts exhibited high activity and stability. For cyclohexene hydrogenation catalyzed by ILPEG75o-stabilized Rh nanoparticles, under the conditions of S/Rh=1000(molar ratio), T=60℃, P(H2)=1MPa and/=1h, the conversion of cyclohexene and TOF was100%and1000h-1, respectively. Catalytic activity remained unchanged within ten successive runs. The leaching of rhodium in organic phase was under the detection limit of ICP-AES (5μg/L)ILPEG750-stabilized Rh nanoparticles were extended to the hydroformylation of olefins. For hydroformylation of1-octene, under the conditions of S/Rh=2000(molar ratio), T=90℃, P=5MPa (CO:H2=1:1) and t=15h, the conversion of1-octene was93%and the yield of aldehydes was86%. The catalyst was reused for eight times without evident loss of activity.ILPEG75o-stabilized Pd nanoparticles were employed as a catalyst for Heck reaction. For Heck reaction of iodobenzene and methyl acrylate,96%yield were obtained under the conditions of iodobenzene/Pd=1000(molar ratio), T=100℃and t=5h, the catalyst could be reused for seven times without evident loss of activity.The thermoregulated ionic liquid and organic biphase system with Ru, Rh, Pd nanoparticles provided a novel solution for separartion and recycling of transition-metal, especially noble metal nanoparticle catalyst.