Preparation of Thermally Stable MCM-41 Mesostructure Using Ethylamine

Abstract

Ethylamine(EA) was used as an additive instead of mineralizers such as NaOH and TPAOH to synthesize MCM-41 molecular sieves with high structural stability and long range order. Small angle X-ray diffraction showed that the EA/CTAB (cetyltrimethylammonium bromide) ratio was the critical factor that determines the degree of ordering in MCM-41. The samples had walls approximately 2 nm thick, which is the thickest level ever reported. Therefore, they did not lose their structure entirely even after heat treatment at 1000°C. Together with the effect of the EA/CTAB ratio, the textural mesoporosity, as confirmed from the N₂ adsorption-desorption isotherm analysis, suggests the EA participates in the templating process of the mesostructure. In addition, the decrease of the lattice parameter and the pore size with increasing EA concentration implies the role of EA as co-surfactant.