Hollow zeolite structures formed by crystallization in crosslinked polyacrylamide hydrogels

Hollow zeolite structures including sodalite spheres and hollow zeolite NaA crystals were synthesized by introducing crosslinked polyacrylamide (C-PAM) hydrogels into zeolite synthesis gels. The synthesis gels with weight compositions of 0.8SiO(2) : 1.0Al(2)O(3) : 21.2Na(2)O : 86.0H(2)O : 7.4-28.7 acrylamide (AM) were used to produce hollow sodalite spheres. The synthesized hollow sodalite spheres had diameters of 1-5 mu m and shell thicknesses of 0.5-1 mu m, and the sphere diameters decreased from 5-10 mu m to 1-3 mu m as the amount of C-PAM increased. Hollow zeolite A crystals with sizes of 300-500 nm were grown from the synthesis gel with a weight ratio of 0.8SiO(2) : 1.0Al(2)O(3) : 2.6Na(2)O : 16.4H(2)O : 2.6-3.8AM. The experimental results suggest that the formation of hollow zeolite structures may involve a surface-to-core crystallization process induced by crosslinked polyacrylamide networks.