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The Application Of PETPP/Ru Complex And PETPP-Stabilized Transition Metal Nanocatalysts In Liquid/Liquid Biphase Systems

Posted on:2009-05-12Degree:DoctorType:Dissertation
Country:ChinaCandidate:Y D LuFull Text:PDF
GTID:1101360242484637Subject:Applied Chemistry
Abstract/Summary:PDF Full Text Request
This thesis is divided into two parts:In the first part, a thermoregulated biphase system composed of n-heptane and poly(ethylene glycol) (PEG) monoalkyl ether, which has the characteristic of being monophasic at higher temperature and biphasic at room temperature, was reported and used for PETPP/Ru (PETPP, P-[b-C6H4O(CH2CH2O)nH]3) complex catalyzed hydrogenation of alkenes. The catalytic activity and recycling efficiency of the catalyst were studied in detail. For the hydrogenation of 1-octene in thermoregulated n-heptane and triethylene glycol monomethyl ether biphase system, under the optimal reaction conditions, the conversion of 1-octene reached up to 100% and the TOF was 333 h-1. Catalytic activity remained almost the same within ten successive runs. Analysis of ICP-AES demonstrated that Ru leaching to the product phase was under the detection limit (5μg/L) of the instrument in this thermoregulated biphase system.In the second part, PETPP-stabilized Ru, Rh and Pd nanoparticles were prepared and characterized in triethylene glycol monomethyl ether, PEG and water. The results indicated that the average diameter of as-prepared nanoparticles ranged from 1 to 3 nm in size with narrow distributions. To further investigate the catalytic activity and recycling efficiency of the nanocatalysts, PETPP-stabilized Ru, Rh and Pd nanoparticles were used as catalysts for hydrogenation reactions in thermoregulated n-heptane/triethylene glycol monomethyl ether biphase system, thermoregulated PEG biphase system and aqueous biphase system.As for the hydrogenation of styrene in thermoregulated n-heptane/triethylene glycol monomethyl ether biphase system and thermoregulated PEG biphase system catalyzed by PETPP-stabilized Ru, Rh and Pd nanoparticles, the whole system formed two phases and the nanocatalysts were in the lower triethylene glycol monomethyl ether phase or PEG phase at room temperature. At the reaction temperature (higher than the miscibility temperature of the system), the whole system became homogeneous and PETPP-stabilized Ru, Rh and Pd nanoparticles could be well dispersed in the system to catalyze the reaction. After reaction, on cooling to room temperature, two apparent phases formed again. The upper phase containing the product of ethylbenzene could be easily separated from the catalyst by simple phase separation and the lower triethylene glycol monomethyl ether phase or PEG phase containing the nanocatalysts could be recycled and reused directly for the next reaction run. PETPP-stabilized Ru, Rh and Pd nanoparticles could be reused for six successive runs without loss in activity.As for the hydrogenation of benzene, benzene derivatives and alkenes in aqueous biphase system catalyzed by PETPP-stabilized Ru, Rh and Pd nanoparticles, PETPP-stabilized Rh nanoparticles gave the best result. Under the optimal reaction conditions, very high TOF of 3333 h-1 and a TON up to 34 700 after seven successive runs were obtained for the hydrogenation of benzene. The rhodium nanoparticles were rather active even at room temperature. As for the hydrogenation of 1-octene at room temperature, after twenty successive runs, a TON of 4 184 000 with a TOF of 200 000 h-1 was obtained.
Keywords/Search Tags:Thermoregulated Non-aqueous Biphasic Catalysis, Aqueous Biphasic Catalysis, Transition Metal Nanocatalyst, Hydrogenation, Benzene
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