Methane Oxidation via Chemical and Biological Methods: Challenges and Solutions

Abstract

Methane, a potent greenhouse gas, has gained significant attention due to its environmental impact and economic potential. Chemical industries have focused on specialized catalytic systems, like zeolites, to convert methane into methanol. However, inherent limitations in selectivity, irreversibility, and pore blockages result in high costs and energy requirements, thus hindering their commercial viability and profitability. In contrast, biological methane conversion using methanotrophs has emerged as a promising alternative, offering higher conversion rates, self-renewability, improved selectivity, and economically feasible upstream processes. Nevertheless, biological methane oxidation encounters challenges including the difficulty in cultivating methanotrophs and their slow growth rates, which hinder large-scale bioprocessing. Another highlighted limitation is the limited mass transfer of methane into liquid in bioreactors. Practical strategies to enhance methane oxidation in biological systems, including optimizing reactor design to improve mass transfer, altering metal concentrations, genetic engineering of methane monooxygenases, enzyme encapsulation, and utilizing microbial consortia are discussed. By addressing the limitations of chemical approaches and highlighting the potential of biological methods, the review concluded that the utilization of genetically engineered methanotrophic biofilms on beads within a biotrickling reactor, along with enhanced aeration rates, will likely enhance methane oxidation and subsequent methane conversion rates.