Novel Mn-based mesoporous mixed oxidic solids

摘要

Manganese-based high surface area mesoporous and/or microporous mixed oxidic solids AMnO_x, where M = Al, La and Fe, have been prepared via controlled hydrolysis of a water sensitive tri-nuclear manganese complex (Mn_3O(CH_3COO)_6(pyr)_3)ClO_4 in aquatic microenvironment (drops). The specific surface area of the obtained solids heated at 300 deg C was found to be 711 m~2/g for AlMnO_x, 247 m~2/g for LaMnO_x and 199 m~2/g for FeMnO_x while the mean pore diameters were 3.6, 4.6, and 3.8 nm respectively. The surface composition of the solids was determined uisng XPS while their texture was checked using AFM. A mechanism of formaiton of the porous oxidic systems is proposed via hydrolytic attack of water molecules in the acetyl bridges of the complex followed by adsorption of A-cations on the Mn(OH)_x groups formed and diffusion limited aggregation (DLA) of the resulting clusters towards larger particles.