Boron coordination and co-incorporation of Al, Ga in BEA borosilicate and dissolution of zeolite nanoparticles from large particles in organic solvents
Borosilicate zeolites have importance applications due to their weak acid sites, which is suitable for certain catalytic reaction and the providing new structure by using as boron source. The boron coordination in beta borosilicates can be transformed from trigonal to tetrahedral boron or vice versa upon hydration/dehydration processes. Especially, at the high degree of hydration, boron can be removed from the framework of the proton form via hydration. Based on this flexibility of the boron coordination, Al and Ga beta zeolites can be formed via post-synthetic treatments with varying the Na+/H+ ratio in dehydrated beta borosilicates. The forming of zeolite nanocrystals has received much attention due to their great potential of applications in catalysis and adsorption. A novel method with organic solvents was applied for preparation of zeolite nanoparticles. Using the polar solvents, such as DMF and DMSO, the zeolite colloidal suspensions with the particle sizes at about 200 nm are formed from the zeolite microparticles. Some parameters, e.g. water and sodium concentrations can affect to the mean particle size of the zeolite nanocrystals
