PHYSICOCHEMICAL PROPERTIES OF SOME MESOSTRUCTURED ALUMINOSILICATES
Dr. M.L. Occelli
Zeolites and Clays Program, GTRI
Georgia Institute of Technology
Atlanta, Georgia 30332
Monday, April 29, 3:30 pm
Ben Bandy Conference Center
Center for Applied Energy Research
Mesostructured aluminosilicates, because of their easily accessible mesoporosity and pore diameter in the 20 angstrom to 100 angstrom range, should prove particularly useful in the preparation of novel catalysts for converting bulky aromatics as well as other high molecular weight hydrocarbons.
To impart the desired catalytic activity to the inert silicate framework, synthesis conditions have been modified to introduce the desired Al concentration in the wall of different MCM-41 type materials. Pore size distributions in the mesoporous region were obtained with the BJH equation using nitrogen sorption isotherms.
Microcalorimetry experiments with ammonia as the probe molecule and FTIR experiments with pyridine, indicate that in these high (800-1200 m2/g) surface area solids, acid site density and strength is weaker than in zeolites, amorphous aluminosilicate gels and in pillared clays.
27Al NMR results show that the synthesis conditions used can generate crystals containing only framework Al(IV). However, after the oxidative decomposition of the templates, extra-framework Al(IV) species appear and a contraction of the unit cell dimension can be observed by XRD.