In situ Synthesis of Micro- and Mesoporous Al-MFI / MCM-41 like Phases with High Hydrothermal Stability.

Abstract Micro- and mesoporous aluminum containing MFI / MCM-41 like composite phases were synthesized in situ using mixtures of C 6 H 13 (CH 3 ) 3 NBr and C 14 H 24 CH 3 NBr templates / surfactants in the ratios of 85%/15% and 15%/25% in the synthesis gels and tested in 100% steam for 5 hours at temperatures of 650 and 815°C, respectively. An improved hydrothermal stability was observed for some of the aluminum containing composites obtained using these mixtures of surfactants, the more interesting samples formed using synthesis temperatures from 168 to 175°C. The two most interesting types of samples were composites consisting of approximately 60%/40% mixtures of MFI/MCM-41 like structures, and of a 95% MFI and 5% mesophase, respectively. The surface area retention for the first type after heating in 100% steam for 5 hours at 815°C was in the range of 45-55% (N 2 -BET surface area (BET-SA) after steaming ca. 215 m 2 /g), while the second type showed a surface area retention of almost 85% (N 2 -BET surface area after steaming ca. 340 m 2 /g). These materials are potentially interesting candidates in ZSM-5 catalyzed processes in which diffusional restrictions have been a limiting factor.