Acta Phys. -Chim. Sin. ›› 2013, Vol. 29 ›› Issue (08): 1809-1813.doi: 10.3866/PKU.WHXB201305161

• PHYSICAL CHEMISTRY OF MATERIALS • Previous Articles     Next Articles

Synthesis of Plate Like Silicalite-1 with Controlled Thickness

YAO Xiao-Qiang1, XU Xiang-Yu1, LÜ Zhi1, JIAO Kun1, SONG Jia-Qing1, LI Zhao-Fei2, WANG Qian2, YAN Li-Jun2, HE Ming-Yuan3   

  1. 1 State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, P. R. China;
    2 Petrochemical Research Institute of Petrochina, Beijing 100195, P. R. China;
    3 Shanghai Key Laboratory of Green Chemistry and Chemical Processes, East China Normal University, Shanghai 200062, P. R. China
  • Received:2013-04-11 Revised:2013-05-16 Published:2013-07-09
  • Contact: SONG Jia-Qing E-mail:songjq@126.com
  • Supported by:

    The project was supported by the National High Technology Research and Development Program of China (863) (2009AA064201) and National Sci-Tech Support Plan, China (2012BAE05B00).

Abstract:

In this study, plate like Silicalite-1 samples with controlled thickness were synthesized using a SiO2-TPAOH-H2O-NH4F (TPAOH: tetrapropylammonium hydroxide) system by careful tuning of the synthetic parameters. Samples were fully characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), and thermogravimetry-differential thermal analysis (TG-DTA). We confirmed that the concentration of NH4F and pH of the initial gel played important roles in controlling sample morphology. The morphologies of the samples changed from ellipse to plate like shapes as the molar ratio of NH4F to SiO2 was increased from 0 to 0.18. In addition, the thickness of the plates was controlled by regulating the amount of NH4F in the gel. The thickness of the sample decreased as the amount of NH4F increased, and reached its minimum when the NH4F/SiO2 molar ratio reached 0.4. Further increase of the molar ratio of NH4F/SiO2 increased the thickness of the plates because of their improved crystallinity. In these plate like particles, the b axis was perpendicular to the plate, as confirmed by HRTEM, which implies that these materials could show good accessibility for guest molecules because the b axis is the straight channel in MFI structures. All of the plate like Silicalite-1 samples were highly stable and their morphologies were retained even after treatment at 1100℃.

Key words: Silicalite-1, Morphology, Plate like material, NH4F/SiO2, HRTEM

MSC2000: 

  • O641