The synthesis of carbonaceous and N-doped carbonaceous TiO2 nanostructures from the MIL-125(Ti) and NH2-MIL-125(Ti) metal-organic frameworks (MOFs) is reported using the Laser Vaporization Controlled-Condensation (LVCC) technique. In this method, the solid MOF targets are vaporized using the second harmonic of Nd-YAG laser (532 nm) in the presence of a 50% O2-He gas mixture. The carbonaceous and N-doped carbonaceous TiO2 nanostructures formed in the gas phase are deposited on the top cold plate (-70 oC) of the LVCC chamber. XRD data indicates the presence of mainly the anatase phase of TiO2 with a minor component from the rutile phase. These nanostructures are used as catalyst support for palladium nanoparticles and the catalyst systems are evaluated for the Suzuki carbon-carbon cross coupling reaction under microwave irradiation. The reaction is carried out between bromobenzene and benzeneboronic acid in the presences of K2CO3 in 50% EtOH/water mixture along with 0.3 mol % of the supported Pd catalyst. The conversions to the biphenyl product by the Pd supported carbonaceous nanostructures (Pd/TiO2/C) and the Pd supported N-doped carbonaceous nanostructures (Pd/TiO2/N-C) prepared from the MIL-125(Ti) and NH2-MIL-125(Ti) MOFs are 73 and 100%, respectively within five minutes of reaction time under microwave irradiation. The conversions for the Pd nanoparticles supported on the parent MIL-125(Ti) and NH2-MIL-125(Ti) MOFs are only 45 and 48%, respectively under identical reaction conditions. The higher activity of the Pd/TiO2/N-C catalyst is attributed to the incorporation of the nitrogen atoms within the carbon lattice of the carbonaceous TiO2 nanostructures.

Synthesis of carbonaceous TiO2 nanostructures by laser vaporization controlled-condensation of MIL-125(Ti) and NH2-MIL-125(Ti) and their applications as catalyst support for Pd nanoparticles for Suzuki cross coupling reactions

254th National Meeting (2017)

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