| In this paper, PEG4000-stabilized rhodium nanoparticle catalysts were prepared by hydrogen reduction of RhCl3·3H2O. TEM characterization showed that the diameter of Rh nanoparticles was1.8±0.4nm. The Rh nanoparticles were used as the catalysts for the hydroformylation of styrene and4-isobutyl styrene(IBS) in the thermoregulated PEG biphasic system. The activity and recycling efficiency of the catalysts were investigated.PEG4000-stabilized rhodium nanoparticles were used as catalysts for the hydroformylation of styrene. The effects of reaction temperature, reaction time, syngas pressure, the molar ratio of styrene/Rh and different molecular weight PEG-stabilized Rh nanoparticles on the reaction were investigated in detail. Under the optimized reaction conditions:T=110℃,t=3h, P=6.0MPa, styrene/Rh=1000:1(molar ratio), both the conversion of styrene and the yield of aldehydes were97%. The Rh nanoparticle catalysts could be recycled20times without evident loss in activity. the average size of Rh nanoparticles was almost the same as those of freshly prepared. The average leaching of rhodium in organic phase was0.58%(wt%). The Rh nanoparticles stabilized by PEG(400,1000,2000,6000,10000and20000) also showed high activity.The Rh nanoparticles stabilized by PEG4000were used as catalysts for the hydroformylation of IBS. The effects of reaction temperature, reaction time, syngas pressure, the molar ratio of IBS/Rh on the reaction were investigated in detail. Under the optimized reaction conditions:T=120℃, t=5h, P=6.0MPa, IBS/Rh=1000:1(molar ratio), the conversion of IBS and the yield of aldehydes were97%and96%, respectively. The Rh nanoparticle catalyst could be simply separated and recycled20times without evident loss in activity. The average leaching of rhodium in organic phase was0.38%(wt%). One of the products2-(4-isobutylphenyl)propionaldehyde is the important intermediate for synthesis of ibuprofen, which is the new generation of analgesic anti-inflammatory drug. |
PDF Full Text Request