2.2.1. Preparation of SBA-15
The mesoporous SBA-15 silica with tuned geometrical structure was prepared using the method described elsewhere (Zhao, 1998). Pluronic P123 (8 g) was dissolved in 60 ml demineralized water and 2 M HCl (240 g) solution under vigorous stirring at 50 ᵒC for 16 h. After the mixture became clear, in a closed vessel, TEOS (17 g) was added dropwise into the solution with continuous stirring at 50 ᵒC for 20 h and then aged at 100 ᵒC for 24 h. The formed solid product was separated by centrifugation, washed repeatedly with de-ionized water and dried at ambient temperature. Controlled removal of the template was managed through the calcination at 550oC for 6h with temperature ramping of 1oC min-1.