ELECTRON-MICROSCOPIC STUDY OF INTERGROWTH OF MFL AND MEL - CRYSTAL FAULTS B-MEL

Recently, a pure MEL type silica zeolite was successfully synthesized by one of the authors. Boron atoms were incorporated into its framewor k structure by using similar synthesis conditions with gels containing boron in an effort to confer catalytic activity. The nature of crysta l faults in the borosilicate-MEL zeolite (B-MEL) was studied using tra nsmission and scanning electron microscopy (TEM and SEM). Electron dif fraction (ED) patterns show characteristic diffuse streaks along the [ 100] and [010] directions. From the analyses of both the diffuse strea ks in ED patterns and high-resolution electron microscopy (HREM) image s, it was determined that the framework structure of the B-MEL crystal has many planar faults that are parallel to the (100) and (010) plane s. The local structure of the planar faults can be interpreted by the intergrowth of the MFI type structure, and a model of the growth proce ss for the B-MEL is speculated from the results.