Influence of binder on the acidity and performance of H-Gallosilicate (MFI) zeolite in propane aromatization

Influence of the addition of alumina or kaolin, as a binder at a concentration of 10 or 50 wt% to H-Gallosilicate (MFI) zeolite on its inter-and intracrystalline acidity, initial activity, product selectivity and distribution of aromatics formed in the propane aromatization (at 550 degrees C) and also on its deactivation due to coking in the aromatization process has been thoroughly investigated. Kaolin binder caused an appreciable decrease in the acidity (both inter-and intracrystalline) and propane aromatization activity of the zeolite. Whereas, alumina binder has no significant effect on the intracrystalline acidity and propane aromatization activity but caused a significant increase in the intercrystalline acidity. The catalyst deactivation and coke deposition on the zeolite are increased due to the alumina binder. But when kaolin binder is used, the coke deposition is not changed significantly. However, the deactivation rate constant for the initial fast deactivation is decreased but for the later slow deactivation is increased by kaolin binder. The selectivity for aromatics and para selectivity of the zeolite are increased by both the binders. The product selectivity, dehydrogenation/cracking and aromatization/cracking activity ratios and para selectivity, particularly for the zeolite with alumina (50 wt%) binder, are strongly influenced by the catalyst deactivation. However, the influence of binder and/or catalyst deactivation on the distribution of aromatics is very small. (C) 1997 Elsevier Science B.V.