The versatile synthesis method for hierarchical micro- and mesoporous zeolite: An embedded nanocarbon cluster approach

In this work, we are reporting for the first time the synthesis of hierarchical micro- and mesoporous zeolite using silicacarbon (SiO2/C) composites prepared by pyrolysis of carbonaceous gases in the presence of silica gel. The pyrolysis effectively yielded carbon deposited onto the raw silica material. The obtained SiO2/C composites were utilised as a bifunctional material, mesoporous template and silica source, for the zeolite synthesis. Tetrapropylammonium hydroxide (TPAOH) was used as a microporous template. The combination of the obtained composites and the TPAOH for the hydrothermal synthesis resulted in the formation of hierarchical micro- and mesoporous ZSM-5. The results from the SEM, TEM, and N2 adsorption/desorption isotherms, and 27Al MAS NMR characterisations of the synthesised samples obtained after the removal of the templates confirmed the successful formation of the micro- and mesoporous zeolites. The mesoporosity of the zeolites could be controlled by adjusting the carbon content in the SiO2/C composites while the carbon content could be controlled by varying the deposition time and the concentration of the carbonaceous gases used. This controllable and efficient synthesis method is considered to be a promising method for creating hierarchical micro- and mesoporous zeolites. (C) 2011 Canadian Society for Chemical Engineering