Alcohol Oxidase and Fe-ZSM-5 Catalytic Coupling for Concerted Methane Fixation at Ambient Condition

Anthropogenic methane emissions to the atmosphere constitute a technical challenge because they are driven by diffuse and dilute sources. The low temperature and concentration of these emission streams make them ill-suited to be addressed by current routes of methane oxidation, which invariably rely on high temperatures or pressures to drive methane oxidation rapidly and efficiently. Herein, we report the catalytic coupling of alcohol oxidase with an iron-modified ZSM-5 that functions as a synthetic methanotrophic system capable of partially oxidizing methane at ambient temperatures and pressures, producing chemically useful intermediates for concomitant material synthesis. Methane reacts at the Fe-ZSM-5, producing methanol, which is oxidized at the enzyme to formaldehyde and hydrogen peroxide. The latter subsequently reacts back at the Fe-ZSM-5 as the methane oxidizer in a unique catalytic couple. We show that the methane-to-formaldehyde selectivity can exceed 90% at room temperature, surpassing the highest literature values to date. The generated formaldehyde intermediate can be rapidly incorporated into a growing urea polymer, with a material growth rate exceeding 5.0 mg gcat hr-1, commensurate and even exceeding rates for many cultured methanotrophic bacteria systems. The resulting carbon-capturing urea-formaldehyde polymer is shown to be successfully incorporated into nanocomposites, with performance comparable to commercially available resin. This work presents a sustainable, scalable, and cost-effective route for concerted methane oxidation at ambient conditions to produce high-value polymers, allowing the unique valorization of ambient methane emission streams.