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

Abstract

State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan, 030001, ChinaMesostructured aluminosilicate nanoparticles with wormhole-like framework structure were synthesized via sol–gel route at lowtemperature using cationic cetyltrimethylammonium bromide (CTAB) as template. Similar to hexagonal AlMCM-41, themesoporous nanoparticles had high surface area and uniform mesopores. It is more desirable that acid sites were generated directlyby calcining the as-synthesized nanoparticles, making a subsequent ion-exchange and calcination treatment superfluous. The acidstrength of acid sites on the present mesoporous nanoparticles was close to that on AlMCM-41 material, but less strong than thatof on microporous HZSM-5 crystals. Although highly acidic HZSM-5 was active for cumene cracking, the nanoparticles andAlMCM-41 were much more catalytically active in bulky 1,3,5-triisopropylbenzene cracking due to the facilitation of diffusion ofreactant/product molecules. More interestingly, the mesoporous Al substituted nanoparticles still exhibited excellent activities in1,3,5-triisopropylbenzene transformation after severe treatment by pure steam at 800 C for 2 h. In contrast, well-orderedAlMCM-41 totally lost its activity after the same treatment.KEY WORDS: sol–gel; mesostructured; nanoparticle; synthesis; catalysis.