Conversion of methane to methanol: technologies and future challenges

In the current period, there is a high demand for the production of liquid fuel which is used for transport purposes all over the world. Therefore, the conversion of methane to methanol fuel is reported as an alternative option for natural gas. Some approaches such as the two-step syngas process, direct single step, and bacterial agent catalyzed reaction use steam reform of methane, methane oxidation processes (via methane selectivity), and methane gaseous form (via methane monooxygenase enzymes) respectively to produce methanol fuel from methane. Also, chemical routes have applied high temperature/pressure catalytic conversion of syngas to methanol. Most conventional approaches discussed are gas to liquid technologies that exploit and monetize nontraditional methanol sources. The utility of methanol as liquid fuel is discussed and now researchers have invented the greatest potential of methanol as a robust product that is produced or synthesized by using a commercial scale conversion process from methane. Normal conversion for methane to methanol via chemical routes is exploited by high temperature and pressure as an energy-intensive process. However, the biological modes of conversion of methane to methanol occur by using methanotrophic bacteria, exhibiting desired transformation capacity at ambient conditions via methane monooxygenase enzyme. Biotechnological modes of conversion have shown the potentiality for their application in an industrially relevant process in eco-friendly ways. Some approaches of biotechnological modes of conversion of methane to methanol by whole-cell, wild-type, and methanotroph cultures are discussed along with many chemical route approaches. In this paper, the authors emphasize the different chemical and biological approaches for methane to methanol conversion with their limitations and applications.