Study of the mechanism of carbonization of template in silicon-substituted aluminophosphate zeolite crystals

Silicon-substituted microporous aluminophosphate AIPO(4)-11 zeolite crystals (SAPO-11) were synthesized by a hydrothermal method. The dipropylamine (DPA) molecules were incorporated in the one-dimensional channels of SAPO-11 as organic templates. The DPA molecules can be pyrolyzed at high temperature, and form 0.3 nm single-walled carbon nanotubes (SWNTs). The detailed carbonization process of DPA molecules has been investigated by using Fourier transform infrared measurements (FTIR), mass spectrometry, thermogravimeter (TG), and micro-Raman spectroscopy. During the pyrolysis process, the DPA molecules decompose into propylene and ammonia at 673 K, and then the C-H bonds of C3H6 Start to break when temperature is above 698 K. The 0.3 nm SWNTs are formed sequentially in the channels of SAPO-11 crystals at about 723 K.