Fifth International FEZA Conference

S1116

Hydrothermal synthesis and structure of a new layered zincophosphate intercalated with 3-Methylaminopropylamine cations

A novel layered zincophosphate (ZnPO–MPA) was prepared by hydrothermal crystallization using 3-methylaminopropylamine (MPA) as a structure-directing agent. The structure consists of macroanion [Zn2P3O8(OH)3]2- layers which are built up of 4-membered ring channels. The channels (of about 3.7 Å diameter) arise through the connection of the neighbouring rings by two oxygen bridges. The negative charge of the layers is compensated by diprotonated MPA molecules which are stacked parallel to the ring channels. ZnPO–MPA is stable up to 300 °C. At higher temperatures MPA decomposition begins followed by a dehydration, which occurs through condensation of the framework hydroxyl groups. The activation energy of the MPA decomposition is high due to the fact that the layers and MPA cations are held together by strong hydrogen bonds

On the thermal degradation of 3-methylaminopropylamine captured inside the aluminum phosphate analog of ULM-3

An open-framework aluminophosphate analog of the fluorogallophosphate structure-type ULM-3 was obtained by hydrothermal crystallization of an aqueous aluminum phosphate suspension in the presence of 3-methylpropylamine (MAPA) and hydrofluoric acid. The open-framework fluorinated aluminophosphate structure was confirmed by Rietveld analysis and the (27)Al, (31)P, and (19)F MAS NMR spectroscopy. The MAPA, located in the ten-membered ring channels, is doubly protonated to balance the negative charge of the Al(3)P(3)O(12)F(2) (2-) framework. Thermogravimetric analysis data have been used to study kinetics of the thermal decomposition of MAPA. The decomposition was found to be a complex process, its activation energy varied from 177 to 259 kJ mol(-1). The relatively high E values are explained by the fact that the MAPA cations are bound to the anionic framework both by electrostatic forces as well as strong N-HaEuro broken vertical bar O hydrogen bonds. The strength of the interactions is indirectly confirmed by the in situ high temperature X-ray diffraction analysis which shows that the MAPA decomposition leads to a phase transformation of the open-framework structure to the dense trydimite phase