Synthesis of mesoporous silica by cationic surfactant templating in various inorganic acid sources

Mesoporous silica materials with well-ordered hexagonal structure were synthesized under acidic conditions. The influences of crystallization conditions, aging conditions, acid sources HX and acid/tetraethyl orthosilicate ratio on the order degree and the morphology have been discussed. The increase of crystallization temperature or crystallization time was beneficial for the condensation of silica species, but had no effect on improving the order degree of mesoporous silica. The order degree of mesoporous materials using various acid sources HX under the same acid concentration swas as follows: HNO3HBrH2SO4HCl which differed from that in the Hofmeister series; the sulfate anions SO42- can play a supporting role on pore structure in the form of space occupation, leading to forming more ordered products than in HCl. Besides, the NO3- and Br- ions showed contrary effect on the growth of micelles, the bigger the pore wall thickness we obtained, the less HBr or the more HNO3 we used.