Size-controlled synthesis of silicalite-1 single crystals in the presence of benzene-1,2-diol

By adding benzene-1,2-diol as a complex agent for silicon into the system: SiO2-TPABr-NaOH-R-H2O (R: benzene-1,2-diol), single crystals of zeolites silicalite-l with different crystallite sizes ranging from 9 x 3 x 2 mu m to 165 x 30 x 30 mu m were obtained. Experimental results showed that crystals synthesized in the presence of benzene-1,2-diol have a much larger size and better morphology than those synthesized in the absence of benzene-1,2-diol, and their sizes were largely influenced by the content of benzene-1,2-diol in the reaction system. The role of benzene-1,2-diol in the hydrothermal reaction mixture has been characterized by Si-29-NMR, and it was shown that silicon-benzene-1,2-diol complex was formed ill the reaction system, which was very important for the synthesis of large single crystals of zeolites. (C) 2000 Elsevier Science B.V. All rights reserved.