Abstract: A method for the synthesis of siliceous or heteroatom-substituted MFI zeolites (M-MFI; M=Si, Ti, Nb, or Ta) with tunable densities of SiOH that depend simply on the ratio of hydrofluoric acid (HF) to structure-directing agent (SDA; tetrapropylammonium hydroxide) used within the synthesis gel. The equilibrated ion exchange between OH? and F? ions forms tetrapropylammonium fluoride in situ, which does not lead to the formation of SiOH defects within M-MFI. Comparisons of infrared spectra from 15 distinct M-MFI materials show that the densities of SiOH groups within M-MFI decrease linearly with the ratio of HF:SDA, independent of the identity of the heteroatom within the framework.

Abstract: The invention provides methods for completely removing aluminum from existing zeolite frameworks that have been previously considered unalterable due to their small pore sizes and stable crystal structures. Consequently, new combinations of metal atoms and zeolite structures can now be made using the methods disclosed herein. Metal atoms that have useful properties for catalysis and adsorption have been integrated into zeolite structures that provide advantageous size selection or solvation properties to increase rates, conversions, and yields of catalytic processes. The disclosed catalysts and methods reduce the cost of synthesizing useful materials and zeolite structures with compositions of matter that have not been reported.