**2. Synthesis and characterization studies on ZSM-5 zeolites**

## **2.1 Synthesis of hierarchical NaZSM-5 and HZSM-5 zeolites**

Synthesis of hierarchical NaZSM-5 zeolite was carried out following the procedure reported by Wang et al. [14] with some modification. The gel of ZSM-5 zeolite was prepared from a homogeneous mixture with molar composition of 1 Al2O3: 64 SiO2: 10 (TPA)2O: 3572 H2O. The mixture was stirred and aged at 373 K for 3 h. About 1 g PDDA was added slowly to the mixture at room temperature and stirred for 24 h. Then, the mixture was transferred into a 200 mL teflon-lined autoclave for hydrothermal process at 423 K for 144 h. Afterward, the as-synthesized zeolite was dried at room temperature followed by calcination at 823 K and labeled as assynthesized hierarchical NaZSM-5 (NaZSM-5 h).

Hierarchical HZSM-5 zeolite was prepared through multiple ammonium exchanges (1 g of NaZSM-5 in 50 mL 1 MNH4 + solution). Afterward, the zeolite was dried at room temperature followed by calcination at 823 K for 3 h to obtain the HZSM-5 zeolite (labeled as HZSM-5 h).

*Partial Oxidation of Methane to Methanol on Cobalt Oxide-Modified Hierarchical ZSM-5 DOI: http://dx.doi.org/10.5772/intechopen.86133*
