Thermoregulated Phase-Transfer Ru Nanocatalyst For The Atmospheric Hydrogenation Of 1,5-Cyclooctadiene

Transition metal nanoparticles（TMNP）often exhibit high activity and selectivity in catalytic reactions,but how to realize the separation and recovery of TMNP as well as the recycling of TMNP is currently a challenge that needs to be solved.In order to solve the above problems,our group designed and synthesized a type of thermoregulated ligand Ph₂P（CH₂CH₂O）₂₂CH₃(L_P1000)with“cloud point”（Cp）property.In this thesis,the thermoregulated phase-transfer Ru nanocatalyst(TPT-Ru_nano)was prepared by reduction of Ru Cl₃·x H₂O in the presence of hydrogen using L_P1000 as a stabilizer.UV-vis and XPS characterization demonstrated the chemical valence of the Ru element in TPT-Ru_nano.The average particle size of the newly prepared TPT-Ru_nano was 1.4±0.3 nm characterized by TEM.³¹P-NMR characterization demonstrated the coordination of the L_P1000 with Ru nanoparticles.Furthermore,the phase transfer temperature of 44℃ was measured for TPT-Ru_nano in water/1-pentanol biphasic system.The TPT-Ru_nano was utilized for the atmospheric hydrogenation of 1,5-cyclooctadiene（1,5-COD）.Under the optimized conditions（T=80°C,t=25 min,1,5-COD/Ru=200（molar ratio））,the conversion of 1,5-COD was>99%,and the selectivity for cyclooctene（COE）was95%.The turnover frequency（TOF）of the reaction was 451 h^-1,which is higher than that ever reported for Ru complex catalysts.The TPT-Ru_nano could be used five times without any evident loss of conversion or selectivity.The results of mercury poisoning experiments showed that the atmospheric hydrogenation of 1,5-COD catalyzed by TPT-Ru_nano might be heterogeneous catalytic process.