Bonding of organic amino, vinyl, and acryl groups to nanometer-sized NaX zeolite crystal surfaces

Nanometer-sized faujasite zeolite (nanoNaX), synthesized with an organic-additive-free approach, was modified with organic functional groups. Raman scattering and solid-state NMR techniques were employed to study the organic components on the zeolites, the structures of the zeolitic frameworks, and the connections between the organosilyl groups and zeolitic silanol groups. Aminopropylsilyl (APS) and vinylsilyl (VS) groups were covalently grafted to the zeolitic surfaces by directly reacting the nanozeolite with corresponding organosilanes. Although the acryloyl group cannot be introduced onto the zeolitic surface by directly reacting nanoNaX with acryloyl chloride, acrylation can be achieved with APS-modified nanozeolite. Si-29 solid-state NMR studies clearly indicate the transformation of zeolitic silicate species from Q(3) to Q(4) with organosilyl modification. This shows that the connections between the organosilyl groups and the zeolitic silanol groups can be represented as RSi(OSizeolite)(x). In the APS-nanoNaX and Acryl-APS-nanoNaX modified materials, the presence of strong T-2 Si-29 NMR resonance signals indicates that the connection is mainly in the form RSi(OSizeolite)O-2. However, in the VS-nanoNaX, the main connection is RSi(OSizeolite)(3) as the Si-29 chemical shift of the organosilyl species is found at -65 ppm, i.e., consistent with a T-3 structure.