Concerted methane fixation at ambient temperature and pressure mediated by an alcohol oxidase and Fe-ZSM-5 catalytic couple

Abstract

Anthropogenic methane emissions, particularly from diffuse and dilute sources, pose a significant challenge for oxidation and valorization as existing methane oxidation routes rely on high temperatures or pressures. Here we report the catalytic coupling of alcohol oxidase with the iron-modified ZSM-5 (Fe-ZSM-5) zeolite catalyst, creating a tandem methanotrophic system that partially oxidizes methane at ambient temperatures and pressures. Methane reacts at Fe-ZSM-5 to produce methanol, which is then oxidized at the enzyme to formaldehyde and hydrogen peroxide. The latter subsequently reacts back at Fe-ZSM-5 and oxidizes methane in a catalytic couple. We show that methane-to-formaldehyde selectivity can exceed 90% at room temperature. The generated formaldehyde was rapidly incorporated into a growing urea polymer, with a material growth rate exceeding 5.0 mg gcat−1 h−1, which matches or exceeds the growth rates of many methanotrophic organisms. This work presents a sustainable route for methane oxidation, driven by oxygen in the air under ambient conditions, producing high-value polymers and valorizing methane emission streams. The development of catalytic systems for sequestering anthropogenic methane emissions from the atmosphere could potentially reduce global warming. Now, coupling the enzyme alcohol oxidase with an inorganic zeolite generates formaldehyde from methane under ambient conditions with 90% selectivity.