Functioned carbon nanotube templated hierarchical Silicate-1 synthesis: On the existence of super-micropore

• Functioned carbon nanotube used as secondary template for zeolite synthesis.
• SWCN was as template in bundle form other than separate nanotube.
• Additional hysteresis loop between 0.1 and 0.2 was found in several samples.
• The hysteresis loop is due to the large crystal size other than real pore.

In present study, the functioned carbon nanotube was used as secondary template for hierarchical Silicate-1 synthesis. Special attentions were paid to the existence of super-micropore (1–2 nm) and additional hysteresis loop between 0.1 and 0.2 in nitrogen adsorption isotherms of the synthesized samples. The main findings of present study are: (1) Silicate-1 with additional mesoporosity can be synthesized with functioned carbon nanotube as secondary template through impregnation or direct hydrothermal synthesis method. The functional group in carbon nanotube doesn't influence the crystallization process with impregnation method but have large influence in direct hydrothermal synthesis method; (2) With typical subsequently impregnation method, no hysteresis loop between 0.1 and 0.2 was found in the nitrogen adsorption isotherms of samples. And the single wall carbon nanotube penetrated the zeolite crystal as a bundle other than separate nanotube with size range in 1–2 nm, (3) In zeolite samples synthesized with direct hydrothermal method, additional hysteresis loop was found in several samples. However, SEM and crystallization process analysis indicated that the hysteresis loop was more likely due to the large crystal size other than the existence of any real pores.

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