Synthesis of Heteroatom Substituted SBA-15 by the “pH-Adjusting” Method

Abstract

A simple and effective method denoted "pH-adjusting" is used to graft a large amount of heteroatoms such as Al and Ti to mesoporous silica material SBA-15. The products prepared by this method show highly ordered mesostructures with large surface areas and uniform mesopore size distribution. The results of ICP, EDX, 27 Al NMR, calcium ion-exchange capacity, and UV-vis spectra show that almost all the heteroatoms added into the initial reaction mixture can be introduced into the products, and moreover, the heteroatoms introduced by this route locate at mainly tetrahedrally coordinated sites. CM0343857 492

Synthesis of tungsten carbide on Al-SBA-15 mesoporous materials by carburization

“…This may indicate a partial filling of the pores by tungsten oxides during calcination. Similar results were found by Wu et al [22] during preparation of tungsten carbide confined in the channels of SBA-15.…”

“…Al-SBA-15 samples were prepared by the pH-adjusting method described by Wu et al [22] as follows: 0.781 g of P123 was dissolved in 25 mL of HCl 2 M. Once dissolved the P123, 1.71 g of TEOS was added drop wise to the solution. The mixture was stirred for 4 h followed by the addition of Al(NO3)3$9H2O to reach Si/Al molar ratios in solution of 2 and 10.…”

“…The mixture was kept in hydrothermal treatment at 373 K for 48 h [22]. Then, the product was filtered, washed with distilled water and dried overnight at 333 K. The sample was then calcined at 723 K (heating rate 2 K/min) for 8 h to remove the copolymer template.…”

“…Among a large number of possible heteroatoms that can be substituted in silicate structures, Al is most favorable from the point of view of generating Brønsted acidity, which is a required property in many industrial reactions [19][20][21]. Direct-synthesis and post-synthesis grafting are two typical methods used for the introduction of heteroatoms in mesoporous silica materials [22]. Wu et al [22] introduced Al and Ti into SBA-15 by the pH-adjusting method in strong acid media, followed by a hydrothermal treatment.…”

“…Direct-synthesis and post-synthesis grafting are two typical methods used for the introduction of heteroatoms in mesoporous silica materials [22]. Wu et al [22] introduced Al and Ti into SBA-15 by the pH-adjusting method in strong acid media, followed by a hydrothermal treatment.…”