Economically viable co-production of methanol and sulfuric acid via direct methane oxidation

Abstract

The direct oxidation of methane to methanol has been spotlighted research for decades, but has never been commercialized. This study introduces cost-effective process for co-producing methanol and sulfuric acid through a direct oxidation of methane. In the initial phase, methane oxidation forms methyl bisulfate (CH3OSO3H), then transformed into methyl trifluoroacetate (CF3CO2CH3) via esterification, and hydrolyzed into methanol. This approach eliminates the need for energy-intensive separation of methyl bisulfate from sulfuric acid by replacing the former with methyl trifluoroacetate. Through the superstructure optimization, our sequential process reduces the levelized cost of methanol to nearly two-fold reduction from the current market price. Importantly, this process demonstrates adaptability to smaller gas fields, assuring its economical operation across a broad range of gas fields. The broader application of this process could substantially mitigate global warming by utilizing methane, leading to a significantly more sustainable and economically beneficial methanol industry. Conversion of methane to methanol via methanol derivatives such as methyl bisulfate (MBS) allows to achieve high selectivity and yield, but separating MBS from oxidizing agents such as sulfuric acid is an energy-intense step. Here, the authors eliminate the need for separation of MBS from sulfuric acid by replacing the former with methyl trifluoroacetate, which is subsequently hydrolyzed into high-purity methanol.