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 si licalite-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 an d better morphology than those synthesized in the absence of benzene-1,2-di ol, and their sizes were largely influenced by the content of benzene-1,2-d iol in the reaction system. The role of benzene-1,2-diol in the hydrotherma l reaction mixture has been characterized by Si-29-NMR, and it was shown th at silicon-benzene-1,2-diol complex was formed ill the reaction system, whi ch was very important for the synthesis of large single crystals of zeolite s. (C) 2000 Elsevier Science B.V. All rights reserved.