The small crystals of the ZSM-5 zeolite were synthesized and stabilized inside pores of granulated silica gel support. The pores were filled with aqueous NaOH-Na2Al2O4-TPABr. During zeolite synthesis the reactants reacted with the silica on the pores wall to form small crystals. 37 wt.-% of ZSM-5 crystals were produced. TEM measurements showed large crystals, 3-5 μm in diameter, on the outer surface of silica grains; medium crystals, 0.5-2 μm, inside the macropores and small crystals, 0.02-0.035 μm, inside the mesopores. The catalytic activity of the supported zeolite H-ZSM-5/SiO2 measured by cracking of isobutane at 410-550°C was 2.2-7.8 times higher than for standard zeolite H-ZSM-5 with the same SiO2/Al2O3 ratio and sodium content depending on the testing temperature.
- Isobutane cracking