Synthesis and application of micro-mesoporous SBA-3 with 1,2-bis(triethoxysilyl)ethane as secondary silica source

Micro-mesoporous SBA-3 silica (named SBA-3-12) has been successfully synthesized using mixed tetraethyl orthosilicate (TEOS) and 1,2-bis(triethoxysilyl)ethane (BTESE) (12:1 by molar ratio) as silica sources. Its micropore volume and relative ratio of micropore-to-mesopore volume are evidently increased in comparison with SBA-3-∞ synthesized using TEOS as single silica source (0.030 cm3/g vs. 0.015 cm3/g and 4.5% vs. 1.9%, respectively). The enhanced microporosity of SBA-3-12 is attributed to the occlusion of some BTESE-derived organic groups into its as-synthesized silica matrix. Upon introducing Ti into SBA-3, Ti-SBA-3-12 shows improved performance in cyclohexene epoxidation with tert-butyl hydroperoxide (TBHP) as compared to Ti-SBA-3-∞ (conversion: 71% vs. 63%; TOF: 33 vs. 27 h−1). This improved performance is attributed to the presence of the micropores inside the mesopore wall that facilitate to expose more Ti sites to substrates.