Lin Bingxiong

Distribution of the Bivalent Nickel Ion in ZSM-5 Molecular Sieves

The structure of zeolite ZSK-5 exchanged with Hi ions under pressure has been determined by diffraction method for polycrystalline materials at 500° C. It was found that there are two possible positions outside the framework for Ni ions to stay. One of them is S I , which is a place near the center of a 6-ring facing the cavity at the intersection of two tunnels, one is about 1.5A from the tunnel wall. It is not inside the tunnel, but is inside a polyhedron formed by the Si (Al) or O atoms neighboring to the tunnel, and is coordinated with 8 skeleton O. Another is S II , a place in the Z-form tunnel parallel to the direction of [100], and is about 1.6A from the center of the 10-ring. S II linkes up with 3 skeleton O. Therefore, the Bronsted acid centers of H-ZSM-5 should be somewhere around this two positions.

Direct-Current Magnetization of Y-Type Zeolites Containing Fe Ions

The dc magnetization of Y-type zeolite containing Fe ions and that after reduction treatment were measured in the temperature range of 1.5-300 K. The samples show paramagnetic behavior. The obtained value for the magnetic moment of the paramagnetic units strongly implies the existence of ferromagnetic coupling between the Fe ion at site I in hexagonal prism and the one at the nearest site I in β cage.

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.

Preparative and Structural Studies on Various Substitutions in the Bi-Sr-Ca-Cu-O System

The samples with the norminal compositions of Bi1.8 M0.2 Sr2 Ca2 Cu3 Oy(M = Pb, In, Sb, Nb) and Bi1.7 Pb0.2 M0.1 Sr2 Ca2 Cu3 Oy(M=In, Sb, Nb) have been prepared and investigated. Only the statistical substitution of lead for bismuth results in the formation of the 110K phase. In the crystal structures of two homogeneous phases Bi1.8 Pb0.2 Sr2 Ca2 Cu3 O10 and Bi1.7 Pb0.2 In0.1 Sr2 Ca2 Cu3 O10, adjacent bismuth layers with one oxygen layer in between display a perfect Aurivillius type structure, and the structural unit (O2Cu)Ca(CuO2)Ca(CuO2) shifts teragonality.

The Cu2+ Ion Migration in the Cunax Zeolite

When CuNaX zeolite is used in petrochemistry as a catalyst, it probably loses copper in the course of reaction. Using the method of polycrystal X-ray diffraction, we have determined three structures of CuNaX zeolites with different amount of adsorbed water. In water saturated adsorption, Cu 2+ ions migrate into supercages of zeolite. With decrease of adsorbed water, Cu 2+ ions return to s(II) position. In conclusion, the mechanism of losing copper is that Cu 2+ ions, migrating into supercages, form intermediate substances with reactants in catalytic reaction and run away.