Synthesis and characterization of SBA-15 modified with alkali metals

LEONARDO ANDRES CANO; MARIA V CAGNOLI; JOSE F BENGOA; JOSE L GARCIA FIERRO; SERGIO G MARCHETTI

JOURNAL OF POROUS MATERIALS

SPRINGER

Lugar: Berlin; Año: 2017 vol. 24 p. 631 - 638

1380-2224

The promotion of the mesoporous solid SBA-15 with different alkaline cations (Li, K and Cs) has been studied. X-ray diffraction at low angles, Nitrogen adsorption at 77 K, Electron transmission microscopy, X-ray photoelectron spectroscopy, atomic absorption spectroscopy and Thermal Programmed Desorption of carbon dioxide were used to characterize the solids. The introduction of alkali metals within the channels of the solid generates basic sites of weak and intermediate strength, which do not exist in undoped SBA-15. Besides, the presence of these ions did not change the structural and textural properties of the original support, only a densification of the channel walls is evidenced. According to the alkali metal used, the order established by the total number of sites obtained is: Li-SBA-15>> K-SBA-15 ≈ Cs-SBA-15, while the order by strength of both types of sites (weak and intermediate) is: Li-SBA-15> Cs-SBA-15> K-SBA-15. These results may lead to the advance in the understanding of the basic sites role in the field of mesoporous materials.