Alkaline earth metal oxides impregnation

To prepare alkali- or alkaline earth-modified zeolites or mesoporous moleeular sieves, identieal general methodologies are used. Thus, alkaline earth eation-exehanged zeolites are prepared by exehange of the zeolite in the sodium form in aqueous solution of alkaline earth metal salts, followed by washing and ealeination. Alkaline earth metal oxides loaded in zeolites are also prepared by impregnation of alkaline earth metal salts sueh as nitrates, aeetates, or ethoxides followed by ealeination (70,215,216). 

A.2. Alkaline Earth Metal Oxides Doped with Alkali Metals Prepared by Impregnation... 

As stated above, a second route for the preparation of alkali-doped alkaline earth metal oxides is impregnation with aqueous solutions of alkali metal salts or hydroxides. As shown by Kijenski et al. (242), the resultant alkali metal-doped... 

Impregnation followed by thermal treatment is commonly used to prepare alkali metal oxide or alkaline earth metal oxide clusters in molecular sieves in order to obtain catalysts with basic properties. A first hint at the usefulness of such procedures was published in 1984 Lacroix et al. reported that cesium-exchanged zeolite X is more active in the side-chain alkylation of toluene with methanol when left unwashed after the cation exchange [1]. Hathaway and Davis [2-4] carried out further systematic studies on the preparation of intrazeoUtic oxide clusters with basic properties. These authors described two methods for the introduction of alkali metal oxides into the pores of faujasites [2j When zeolites X and Y, ion-exchanged at room temperature with aqueous solutions of alkali metal acetates or... 

The modifying agents initially used were oxides, and alkaline earth metal salts were impregnated on HZSM-5, and, after calcination, the oxide entered into the channels of... 

We have recently suggested a new approach to the preparation of active sites in sulfated zirconia catalysts [5, 6]. In this case, the catalysts are prepared by deposition of sulfate ions on crystalline zirconium dioxide samples with highly defective structure. According to numerous reports, the monoclinic phase typical for ZrOa is not suitable for this purpose. We have shown that active materials could be obtained by impregnation of zirconia-based oxides with cubic crystalline structure. It should be noted that the cubic structure is not thermodynamically stable for pure zirconia at low temperatures. It can be stabilized by introducing different additives, in particular, alkaline-earth metal cations [7]. Recently, similar results have been obtained for ZrOa stabilized by Y2O3 [8]. 

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