Shynthesis And Catalytic Property Investigation Of Pd/Si-MCM-41 And Cu₂O Nanoparticles

In recent years, with the development of fine chemical industry, the demands ofcatalyst increased. Mesoporous molecular sieve MCM-41 with highly ordered porestructure, highly specific surface, tuned pore diameter is widely used in number ofhydrogenation reactions and in organic synthesis.Over the past several decades, cuprous oxide （direct bandgap 2.2eV） has attractedmuch interest because of its potential applications in catalysis, biosensors, andmicro/nanoelectronics. In this paper, we reported a simple route to the synthesis ofPd/Si-MCM-41 and octahedral cuprous oxide at room temperature. The growthmechanism and catalytic properties had been discussed.（1）The pure silica mesoporous molecular sieve MCM-41 was synthesized underhydrothermal conditions. Pd/Si-MCM-41 was prepared by the incipient wetnessimpregnation of pure silica MCM-41 with PdCl₂ as precursor and reduced byN₂H₄·H₂O. The samples were characterized by XRD, TEM, IR, TG-DSC and ICPmeasurements. The formation of Palladium nanoparticles and nanowires were found toreduce the crystallinity of the Si-MCM-41 framework.The structure of Pd/Si-MCM-41was clearly maintained after impregnation. The designed Pd/Si-MCM-41 mesoporousmaterial was used as catalysts for hydrogenation of rosin. The content of hydroabieticusing Pd/Si-MCM-41 as catalyst was 10％higher than that using Pd/C （5 wt％） ascatalyst.（2）Octahedral Cu₂O and Cu₂O nanowires were synthesized by a simple solution-phase route at room temperature. Octahedral Cu₂O was used to catalyzecarbon nanofibers at 235℃using acetylene as the only carbon source. The sampleswere characterized by XRD, TEM, SEM, IR andTG-DSC measurements. The XRDresults indicated that the carbon nanofibers were composed of amorphous carbon andthe Cu₂O was reduced during the catalysis reaction. SEM and TEM images indicatedthat the obtained nanofibers had mean diameter of 400～500 nm, which is in goodagreements of the size of Octahedral Cu₂O. IR analyses revealed that the nanofibersconsist of both unsaturated -CH=CH- and saturated -CH, -CH₂, and -CH₃ groups.TG-DSC indicated the nanofibers underwent thermal decomposition to release new（gaseous） hydrocarbon species with a low molecular weight, resulting in a weight lossof the nanofibers. The growth mechanism of caibon nanofibers had been discussed.