RECENT PROGRESS ON THE DIRECT CONVERSION OF METHANE TO METHANOL

Methanol is a valuable industrial chemical that serves as a clean fuel and a precursor to many high-demand chemicals like acetic acid, methyl tertiary butyl ether, dimethyl ether, formaldehyde, methyl halides, and methylamine, among others. Methane on the other hand is an abundant gas that constitutes about 85-96 %wt of natural gas compositions obtained from the cracking of petroleum or as a byproduct of coalification or biomass fermentation process. It is reportedly the second most abundant greenhouse gas emitted into the atmosphere after CO2 and also has 25 times as much greenhouse effect as CO2. Therefore, the conversion of methane to methanol is a transformative approach to creating fuels and important chemical feedstocks and intermediates and also a sustainable way to reduce the emission of greenhouse gases and mitigate global warming. Currently, methanol is manufactured industrially at a commercial scale from methane via the indirect energy-intensive syngas/FTS route which is expensive and environmentally unfriendly and proceeds at high temperatures and pressures. Therefore, direct conversion of methane to methanol is desirable to replace the indirect syngas/FTS with the possible advantages of reduced energy consumption, simplified process routes, and potentially higher selectivity and yield. This mini-review explores the recent advancement in the different direct-methane-to-methanol conversion methods, challenges, and opportunities.