Gui Linlin

Application of ion scattering spectroscopy to investigations of the interaction between the active component and carrier in supported catalysts

In this article we will show, however, that the electronic effect is measurable for Cu, Zn, and Na by the ISS technique, and we will use the concept of «effective mass» based upon a binary collision approach to develop a method for the determination of the chemical shift in solid-solid surface interactions in catalyst systems. A series of Cu, Na, and Zn compounds, Al foil, and supported Cu and Zn catalysts have been investigated, and the 4 He + scattering energy from the different atoms in the different compounds or catalysts has been determined. The «mass increments» in these samples are calculated from scattering peak shifts in the ion scattering spectra and the «mass increment» is used as a means to characterize interaction between surface atoms

The Significance Of The Mullite Phase In A Silver Catalyst For The Oxidation Of Ethylene Into Ethylene Oxide

An α -alumina support with suitable pore structure and good heat transfer properties has been prepared. Silver dispersed in uniform grains of suitable size is important for the selectivity of the silver catalyst. We tried various preparative procedures to disperse silver on the support, and found out that the master key to success was the addition of a mullite phase to the α-alumina support. On recognizing the significant role played by the mullite phase, we prepared the support for the silver catalyst from corundum and alumina-silica gel. Satisfactory results have been obtained.

Preparation of Tio2—Al2O3 by Impregnation with TiCl4—CCl4

Catalyst carrier TiO2—Al2O3 was prepared through impregnation γ—Al2O3 with non—aqueous solution of TiCl4 (e.g. carbon tetrachloride or acetone as solvent), followed by calcination at 550°C for 24 h. Series of TiO2—Al2O3 samples with various TiO2 loadings have been characterized by XRD, XPS, TEM and HEED techniques. The maximum dispersion capacities for TiO2 on γ—Al2O3 measured by XRD and XPS are 0.12g TiO2/g γ—Al2O3 and 0.11g TiO2/g γ—Al2O3, respectively. It was also verified by TEM and HEED techniques. This value illustrates that TiO2 disperse on the surface of γ—Al2O3 as a submonolayer and the observed monolayer coverage for TiO2 on γ—Al2O3 is 58% as compared with a close—packed monolayer model.

Solid/Solid Adsorption

We have found experimentally that many solids can disperse spontaneously onto supports to form a monolayer or submonolayer. This is a quite widespread phenomenon) which has not been recognized before. We call it solid/solid adsorption. This phenomenom may be attributed to the formation of strong surface bonds between the atoms, ions or molecules of these solids and the surface of the supports. Another driving force for this phenomenon is the entropy increase associated with the changing from an ordered three-dimensional crystalline phase to a less ordered two-dimensional phase. In addition, the diffusion of atoms along the surface is much easier than that into the bulk of a support, so under suitable conditions the monolayer dispersion may be a stable state.