2.2.2. Propyl sulfonic acid functionalized SBA-15
For surface functionalization of SBA-15 with sulfonic groups, of SBA-15
was firstly dispersed in toluene, and of 3-mercaptopropyl-
trimethoxysilane was added portion wise to the suspension (Wang, 2018).
The suspension was then stirred at for 8 h in nitrogen atmosphere. Then,
the mixture was filtered off and the surface modified SBA-15 with thiol
(-SH) groups was washed three times with ethanol to remove the residual
solvent and unreacted reagent. The obtained white solid was dried at
under vacuum for 12 h and denoted as SBA-15-TH. The anchored thiol
groups (SBA-15-TH) were oxidized with dilute
H2O2 in methanol under argon atmosphere
for 4h (Karimi, 2012). Then, the solution was filtered off and washed
with ethanol/water solution. The wet material was suspended in 1M
H2SO4 for 2h. Finally, the
functionalized silica was washed several times with ethanol/water
solution and dried at 60oC under vacuum overnight,Scheme 1.