CHARACTERIZATION AND CATALYTIC PERFORMANCE OF MESOPOROUS MOLECULAR-SIEVES AL-MCM-41 MATERIALS

Mesoporous Al-MCM-41 materials of different Si/Al ratios have been syn thesized and characterized by X-ray powder diffraction, Al-27 and Si-2 9 MAS NMR, differential thermogravimetric analysis, N-2 adsorption mea surements, FT-IR and catalytic cracking of alkanes. The experimental r esults show that the incorporation of aluminium into the framework of MCM-41 has a great effect on the degree of long-distance order, the su rface acidities and the mesoporous structures of the materials. With i ncrease of the aluminium content, the amounts of tetrahedral framework aluminium and the acid sites on the samples increase, but the acid st rength decreases. Al-MCM-41 materials exhibit high activity for n-C-16 (0), cracking and good selectivity for producing low carbonalkylenes, particularly for i-C-4(=).