EFFECT OF HIGH-TEMPERATURE STEAM TREATMENT ON ACIDIC AND CATALYTIC PROPERTIES OF CATALYSIS FOR AROMATIZATION OF LOWER ALKANES

The effect of high-temperature steam treatment of high-silica zeolites (HSZ) modified with zinc and gallium on their activity and catalytic properties with respect to the aromatization of lower C3-C4 alkanes is studied. The introduction of modifying gallium and zinc additives int o H-HSZ improves the activity and selectivity of the zeolite-containin g catalysts with respect to the formation of aromatic hydrocarbons. Th e high-temperature steam treatment is shown to result in partial dealu mination of the zeolite and decrease in the proton-donor power and con centration of acidic centers. The reactions applying to catalysts trea ted in this way yield products with a lower content of aromatic (espec ially polycyclic) hydrocarbons and a higher concentration of lower ole fins.