Comparative study on the structural, acidic and catalytic properties of nano-sized and large-particulate mesoporous aluminosilicates

Mesostructured aluminosilicate nanoparticles with wormhole-like framework structure were synthesized via sol–gel route at low temperature using cationic cetyltrimethylammonium bromide (CTAB) as template. Similar to hexagonal AlMCM-41, the mesoporous nanoparticles had high surface area and uniform mesopores. It is more desirable that acid sites were generated directly by calcining the as-synthesized nanoparticles, making a subsequent ion-exchange and calcination treatment superfluous. The acid strength of acid sites on the present mesoporous nanoparticles was close to that on AlMCM-41 material, but less strong than that of on microporous HZSM-5 crystals. Although highly acidic HZSM-5 was active for cumene cracking, the nanoparticles and AlMCM-41 were much more catalytically active in bulky 1,3,5-triisopropylbenzene cracking due to the facilitation of diffusion of reactant/product molecules. More interestingly, the mesoporous Al substituted nanoparticles still exhibited excellent activities in 1,3,5-triisopropylbenzene transformation after severe treatment by pure steam at 800 °C for 2 h. In contrast, well-ordered AlMCM-41 totally lost its activity after the same treatment.