**5. Future prospect**

### **5.1 Utilization of synthesis of hierarchical NaZSM-5**

Synthesis of zeolites using natural resources such as kaolin, natural zeolites, coal fly ash, and rice husk has drawn many researchers since decades ago [25]. Especially in developing countries, this work by Chareonpanich et al. [26] has been a success to the synthesis of ZSM-5 zeolite from lignite coal fly ash and rice husk to produce microporous ZSM-5. Our group has reported the synthesis of hierarchical ZSM-5 using similar procedure, with addition of secondary template (labeled as nZSM-5) [27] as the synthesis mentioned earlier in this chapter. The zeolite from this work has MFI structure although the crystallinity was lower than the pro-analysis sourcedsynthetic ZSM-5. Nevertheless, the activity of Co/nZSM-5 was comparable to that of Co/cZSM-5 (prepared from commercially available NaZSM-5 with Si/Al 6.82). Synthesis of ZSM-5 using kaolin and natural zeolite and its activity as catalyst for methane oxidation is also carried out, and it is still an undergoing work.

### **5.2 Bio-methane as feed**

Biogas is one of environmentally friendly renewable energy sources, and its utilization is very economically profitable [28]. Biogas is generally produced from anaerobic organic waste derived from the environment such as livestock manure, containing methane and carbon dioxide as the largest component and a small amount of nitrogen compounds, oxygen, hydrogen sulfide, halogen compounds, and aromatics [29]. In general, biogas can be used in combustion engines [28]; however, direct use of biogas on combustion engines can produce toxic emissions with low efficiency of biogas utilization. In our work [29], utilization of biogas as feed to be partially oxidized to methanol has been studied. Since biogas, obtained from the local biogas farm industry, consists mainly of methane (83.7%) and oxygen (16%), it is directly used without purification. The challenge faced was to compress the biogas in order to feed the reactor as much as the ultrahigh purity (UHP) methane

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

gas. This is due to the relatively high oxygen content. Thus, the concentration of biogas (0.17 bar) fed to the reactor was much lesser than the previous UHP methane gas (0.75 bar). Nevertheless, the partial oxidation reaction of methane without additional oxygen gave 10.99% of percentage (%) yield of methanol compared to 40.56% when UHP methane was used.
