Iron polymeric hydroxygroups pillared clays(Fe-PILC) were prepared by Na+-montmorillonite with iron pillaring agent. 2.01Au/Fe-PILC catalyst was obtained by deposited-precipitation(DP) method. 2.52Au/Fe-oxide catalyst was prepared by co-precipitation method. The catalytic activity of these catalysts was measured by catalytic combustion of formaldehyde. The catalyst of 2.01Au/Fe-PILC exhibits the high catalytic activity. The catalytic combustion reaction of formaldehyde proceeds at considerable rates at 20 ℃ and complete burn-off of formaldehyde is achieved at 120 ℃. The structure of catalysts,the valence state of gold and the size of gold particles were investigated by means of X-ray powder diffractometry,X-ray photoelectron spectroscopy and transmission electron microscopy. The results show that gold atoms with partially positive charge exist in the catalyst and play an important role in the catalytic activity. In addition,nano-sized,well-dispersed gold particles and good adsorption properties of support are necessary to obtain high activity Au catalysts for catalytic combustion of formaldehyde.
A microemulsion-mediated hydrothermal method for synthesis of YVO4:RE(RE=Yb 3+/Er 3+,Yb 3+/Tm 3+)nanoparticles by hydrothermal treatment of quaternary microemulsion medium consisting of Na3VO4/NaOH and RE(NO3)3 aqueous solution, surfactant cetyltrimethylammonium bromide(CTAB),cosurfactant n-hexanol and oil phase n-heptane was report.The confinement of microemulsion droplets acting as microreactors during the reaction process allows the formation of small size YVO4:RE nanoparticles with relatively narrow size distribution and less aggregation.The structure,size and shape of YVO4:RE nanoparticles were investigated by means of X-ray diffractometry(XRD)and transmission electron microscopy(TEM).Compared with the conventional solid annealing diffusion method,the microemulsion-mediated hydrothermal method shows superiority in obtaining YVO4:RE nanoparticles with controllable size,narrow size distribution and less aggregation.The microemulsion-mediated hydrothermal method may be potentially applicable for synthesis of other rare earth doped up-converting luminescence nanomaterials.
