Synthesis and characterization of highly ordered mesoporous molecular sieve, MCM-41

Abstract

Mesoporous molecular sieve MCM-41 has been synthesized and characterized using physicochemical techniques, such as XRD, TEM, $^{129}Xe$ NMR, $^{29}Si$ MAS NMR, nitrogen adsorption, etc. MCM-41 was synthesized by hydrothermal reaction of sodium silicate and cetyltrimethylammonium ion. The thermal and hydrothermal stability of the synthesized MCM-41 were investigated by thermal treatment at a given temperature in $O_2$ flow with or without the water bubbling. The formation of MCM-41 from sodium silicate and CTACl in aqueous solution was very sensitive to pH adjustment. It was suggested that the MCM-41 and NaOH are in equilibrium, which shifted by acid titration. That is, the repeated titration of the product NaOH produced in the synthesis with acetic acid to pH $\sim$ 11 shifts the reaction equilibrium toward the formation of MCM-41. Thus, the long-range structural order and textural