Influence of the Silica-to-Surfactant Ratio and the pH of Synthesis on the Characteristics of esoporous SBA-15

Mesoporous silica SBA-15 was synthesised with two different sets of synthesis conditions and was characterised using nitrogen adsorption, X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The effects of the ratio of tetraethylorthosilicate/triblockcopolymer (TEOS/TCP) (1.52–3.38) and pH (1.3–3.0) were particularly studied. Well-ordered hexagonal mesoporous silicas were formed at a TEOS/TCP ratio of 2.25 and a pH above 2. The highest surface area and an intense XRD pattern were shown by those synthesised at a ratio of 1.52 (669 m2/g and 0.5 cc/g). A high TEOS amount disturbed the condensation of the silica network, causing failure in the formation of the Si-O-Si network