Modified molecular sieve macrostructures

Abstract: The preparation of molecular sieve based catalysts in appropriate macroforms suitable for practical utilization is of great technological importance. This thesis is dedicated to the preparation of metal containing molecular sieve macrostructures (modified macrostructures). Modified molecular sieve macrostructures were prepared by the resin templating method. Firstly, molecular sieves were synthesized within the pore structure of macroporous anion exchange resin beads. After this step, a certain degree of ion exchange capacity is retained by the resin facilitating the secondary insertion of metal anions. Metal anionic species were ion exchanged into the resin-molecular sieve composites obtained in a following step. Finally, the resin was removed by calcination leaving behind self-bonded metal containing molecular sieve spheres with a shape and size similar to the original resin beads. V, W, Cr and Pd containing macrostructures were prepared by the method. Resin-silica composites, in which the structure of the silica was changed from amorphous to crystalline silicalite-1 were used for the preparation of the V and W spheres. The Cr and Pd containing spheres were prepared from resin-zeolite beta composites. The properties of the product spheres (metal content, crystallinity, morphology, nature of the metal species, etc.) were extensively characterized by atomic adsorption spectrometry, X-ray diffraction, scanning electron microscopy, energy dispersive, Raman and UV-vis spectroscopy, nitrogen adsorption and chemisorption measurements. The materials prepared are of interest for application mainly in the area of catalysis.