Esterification Product Protection Strategies for Direct and Selective Methane Conversion

Abstract

A scale-flexible process for the direct and selective oxidation of methane to primary oxygenates is of great interest, however, a commercially feasible approach has yet to be realized due to a number of challenges. Low product yields imposed by a well-established selectivity-conversion limit are particularly burdensome for direct methane-to-methanol chemistry. One strategy that has emerged to break out of this limit is the in situ esterification of produced methanol to the more oxidation-resistant methyl ester. However, these methaneto-methyl-ester approaches still elude commercialization despite their unprecedented high yields. Herein, we outline some of the key barriers that hinder the commercial prospects of this otherwise promising route for highyield direct catalytic methane conversion, including extremely corrosive reagents, homogeneous catalysts, and inviable oxidants. We then highlight directions to address these challenges while maintaining the characteristic high performance of these systems. These discussions support the efficacy of product protection strategies for the direct, selective oxidation of methane and encourage future work in developing creative solutions to merge this promising chemistry with more practical industrial requirements.

Heterogeneous Mn-Based Catalysts for the Aerobic Conversion of Methane-to-Methyl Trifluoroacetate

“…As a consequence of the high stability of the methyl ester in the reaction environment, these methane-to-methyl-ester (MTME) systems successfully break through the selectivity–conversion barrier that is ubiquitous for direct-methane-to-methanol (DMTM) systems . Despite unprecedented yields, there remain several challenges for this chemistry, particularly the use of corrosive and concentrated acids, economically inviable oxidants (e.g., K 2 S 2 O 8 , SO 3 ), and homogeneous catalysts . According to techno-economical evaluation, only the use of oxygen as the oxidant is viable .…”