INFLUENCE OF DESILICATION CONDITIONS ON THE SYNTHESIS OF HIERARCHICAL ZEOLITE Y

Abstract

Hierarchical zeolites were synthesized by two methodologies, following desilication procedures of commercial zeolites. Starting from USY zeolite (Zeolyst CBV720, Si/Al=15), the effect of the amount of CTAB in the desilication media and the hydrothermal treatment time on the synthesized materials were analyzed. The results showed that the surfactant amount has a higher influence on relative crystallinity (%RC) and textural properties of the materials than synthesis time. All the samples showed a lower BET surface area compared with the starting zeolite, although mesopore surface area increased from 210.33 to 467.30 m2/g in the case of Z720-75 sample. In the case of USY zeolite with Si/Al=2.6 (Zeolyst CBV500), a previous dealumination with H4EDTA and an acid washing with Na2H2EDTA steps were included. It was found that the micropore and the mesopore surface areas increased 13.96% and 11.23%, respectively, compared with the parent zeolite; furthermore, the %RC was 99% after treatment procedures.

Keywords

• desilication
• ctab
• nh4oh
• hydrothermal treatment
• hierarchical zeolite