Dry Mixing Method as an Effective Method of Modification of Zeolite Catalysts

摘要

The preparation of zeolite catalysts by the method of dry mechanical mixing in mills of various types attracts attention both due to the simplicity of the experiment and the impossibility to modify the zeolite by traditional methods of impregnation and ion exchange in some cases. The change in the properties of ZSM-5 zeolites can be initiated by dry mechanical mixing both by the mechanical action on the crystalline structure of the zeolite and the addition of modifying additives, in particular, nanoscale metal powders, which being added to the zeolite by traditional methods lose their unique properties. Intensive mechanical action on the zeolite results in a change in its crystalline structure and promotes a decrease in the specific surface area and acidity of the catalyst. When nanoscale metal powders are introduced into the zeolite using the method of dry mechanical mixing, they are mainly located on its outer surface, without changing the crystal lattice parameters but reducing acidity. Both methods of modifying the zeolite results in a decrease in its aromatization activity and increase in its isomerization activity during the treatment of the straight-run gasoline oil fraction. They also contribute to an increase in the yield in gasolines with improved environmental characteristics.