Composite SBA-15/MFI Type Materials: Preparation, Characterization and Catalytic Performance

Abstract

SBA-15 type mesoporous molecular sieve was prepared and used as a parent material for synthesis of a SBA-15/zeolite composite. Thus, after addition of an aluminum source into the pristine sample, it was subjected to recrystallization in the water-vapor phase to give the SBA-15/MFI composites. The samples obtained were characterized by XRD, nitrogen sorption, scanning and transmission electron microscopies, 27Al MAS NMR and FT IR. The materials after recrystallization retained their mesoporous character. Characteristics of the material revealed that all the aluminum added was inserted into the final hybrid. As shown by FT IR and NMR, at least some of aluminum was introduced into the nanoparticles of MFI and adopted four-fold coordination, typical for zeolites. Formation of Bronsted acid centres was directly confirmed by IR studies. The catalytic activity was screened in the liquid-phase isomerization of α-pinene. The main products of α-pinene transformations were camphene, limonene and γ-terpinene. The overall selectivity toward camphene + limonene was ca. 90%. Taking into account the low amount of the MFI phase present in a composite sample, calculated initial reaction rate was comparable with other catalytic systems explored in the isomerization of α-pinene.