Microkinetic characterization of ROS-driven methane production through quantum and classical simulations

Abstract

Methane is ubiquitous in natural and engineered settings, but the mechanisms of reactive oxygen species (ROS)-driven methane production in living organisms remain unclear. Unraveling the interactions and microkinetics among ROS, iron species, and organic methyl groups (MET) is crucial for reducing emissions and optimizing energy recovery. In this study, the quantum Harrow–Hassidim–Lloyd (HHL) algorithm and classical Levenberg–Marquardt (LM) algorithm were employed to: (1) investigate the primary pathway of Fe³⁺ and ascorbic acid (ASC) reactions, (2) determine the kinetic parameters for the reaction between [Fe^IVO]²⁺ and MET, and (3) simulate the ROS-driven methane production pathway under specific abiotic conditions. The results revealed that Fe³⁺ and ASC are primarily responsible for the redox reaction, with a kinetic rate constant of 1.83 × 10⁻⁴ M⁻¹ s⁻¹ for the reaction between [Fe^IVO]²⁺ and MET, and a ∼10% conversion rate of MET to methane. Our study establishes a theoretical framework for ROS-driven methane production. While identifying a feasible pathway for engineered and natural systems, further investigation and validation are needed to quantify its specific contribution in complex environments. Furthermore, this work demonstrates the potential of hybrid quantum-classical simulations for microkinetic analysis.