Preparation Of Au/C And Its Catalysis Of Hydrogenation Of Cinnamaldehyde

The multiwall carbon nanotubes ?MWCNTs?, mesoporous carbon ?MC? and active carbon ?AC? were treated in HNO₃/H₂SO₄ mixtured solution and then used as supports for preparation of Au/C catalysts. The selective hydrogenation of cinnamaldehyde ?CAL? was investigated over the synthesized Au/C catalysts. The obtained catalysts were characterized using techniques of X-ray diffraction ?XRD?, nitrogen absorption-desorption, transmission electron microscopy ?TEM?, Fourier transform infrared spectroscopy ?FTIR? and X-ray photoelectron spectra ?XPS?. It was found that supports and catalyst preparation methods affected the activity and selectivity of Au/C catalysts. Effects of preparation methods on the size of Au nanoparticles, the structure of supports and the size of Au particles on the catalytic performance were investigated. The main contents and conclusions are shown below:Au/MWCNTs were prepared by sol-gel immobilization ?SIT? method and incipient impregnation ?IMP? method, respectively. Effects of preparation methods on the size of Au nanoparticles, the structure of supports and the size of Au particles on the catalytic performance were investigated. It was found that the prepration method affected the degree of dispersion and size of Au nanoparticles over Au/MWCNTs catalysts. Au nanoparticles with smaller size showed higher CAL conversion and the higher selectivity to C=O over the higher Au particle size on Au/MWCNTs. The size of Au nanoparticles also greatly affected the selectivity of products over Au/MWCNTs.Using SBA-15 as a hard template agent, the obtained MC had orderly mesoporous. The corresponding Au/MC prepared using SIT method showed smaller size ?mean size of 5 nm? and higher degree of dispersion. However, the obtained Au/MC prepared using IMP method showed a bigger particle mean size of 25 nm.The effects of reaction conditions, such as reaction time, stirring speed rate, catalyst loading amount, temperature and pressure, were investigated for the selective hydrogenation of CAL over Au/C catalysts.