Enhanced hydrothermal stability obtained for in situ synthesized micro- and mesoporous MFI / MCM-41 like phases

Abstract Micro- and mesoporous MFI / MCM-41 like phases, synthesized using mixtures of C 6 H 13 (CH 3 ) 3 NBr and C 14 H 29 (CH 3 ) 3 NBr templates / surfactants, were tested in 100% steam for 5 hours at temperatures of 650, 760 and 815°C, respectively. A generally improved hydrothermal stability was observed for the composite samples obtained using this mixture of surfactants in the synthesis gels. The most stable sample synthesized with a C 6 H 13 (CH 3 ) 3 NBr / C 14 H 29 (CH 3 ) 3 NBr ratio of 75%/25% at a temperature of 175°C, consisting of about 10% MFI and 90% MCM-41 structure, maintained a N 2 -BET surface area (BET-SA) of 243 m 2 /g after steaming at 815°C, corresponding with a retention of 62% for this sample, which is very high for regular mesoporous phases. The XRDs and N 2 adsorption isotherms reveal that the typical features of the mesoporous materials (low angle peak in the XRD; inflection point in the N 2 -isotherm) are partly maintained. Consequently, this material is an interesting candidate for catalytic cracking and other applications if properly modified.