SILICA-SUPPORTED SMALL CRYSTALS OF ZSM-5 ZEOLITE

The small crystals of the ZSM-5 zeolite were synthesized and stabilize d inside pores of granulated silica gel support. The pores were filled with aqueous NaOH-Na2Al2O4-TPABr. During zeolite synthesis the reacta nts reacted with the silica on the pores wall to form small crystals. 37 wt.-% of ZSM-5 crystals were produced. TEM measurements showed larg e crystals, 3-5 mum in diameter, on the outer surface of silica grains ; medium crystals, 0.5-2 mum, inside the macropores and small crystals , 0.02-0.035 mum, inside the mesopores. The catalytic activity of the supported zeolite H-ZSM-5/SiO2 measured by cracking of isobutane at 41 0-550-degrees-C was 2.2-7.8 times higher than for standard zeolite H-Z SM-5 with the same SiO2/Al2O3 ratio and sodium content depending on th e testing temperature.