Published Online: 15 DEC 2011
Copyright © 2011 John Wiley & Sons, Ltd. All rights reserved.
Encyclopedia of Inorganic and Bioinorganic Chemistry
How to Cite
Hashiguchi, B. G., Hövelmann, C. H., Bischof, S. M., Lokare, K. S., Leung, C. H. and Periana, R. A. 2011. Methane–to–Methanol Conversion. Encyclopedia of Inorganic and Bioinorganic Chemistry. .
- Published Online: 15 DEC 2011
Natural gas (NG) is an abundant, clean, underutilized fossil fuel that can augment or replace petroleum as the feedstock to fuels and chemicals. However, given the relatively high transportation costs for this highly volatile gas, utilization of NG will only be possible if inexpensive, efficient, large-scale technologies can be developed to chemically convert NG to liquids feedstocks (e.g., long chain alkanes or methanol). Current syngas-based technologies can carry out this chemical conversion with very high carbon yield (∼70%) while utilizing the only economically viable co-reactant on this enormous scale: dioxygen or ideally air. However, despite these attractive characteristics, these processes are too expensive to displace petroleum primarily due to the high capital costs associated with the high temperatures required to generate syngas. Substantial effort toward the development of less expensive, lower temperature (<250 °C) processes for the selective, high-yield oxidative conversion of methane, the major component of NG, to functionalized products has yielded a number of potential systems. This article is focused on one very promising approach: the use of homogenous organometallic and/or inorganic complexes in liquid solutions to mediate the oxidative conversion of methane. Heterogeneous (gas/solid) systems are not covered. Considering the ultimate goal of replacing petroleum with NG, we have organized this article with respect to both fundamental chemistry as well as the important practical considerations of whether or not systems can utilize dixoygen as the ultimate co-reactant. Two fundamentally different mechanistic strategies have emerged: (i) the use of coordination catalysts that coordinate and cleave the CH bond of methane (defined as CH activation) or that coordinate and activate the co-reactant (defined as oxidant activation), and (ii) the use of chain reactions based on reactive species such as free radicals or other chain carrying species. Systems that fall into these two categories are further categorized with respect to whether or not oxygen is or can be utilized as the ultimate co-reactant. The goal is to provide the reader with an efficient way of quickly finding or classifying the rapidly growing body of literature by reaction mechanism and co-reactant utilized.
- CH activation;
- homogenous catalysis;
- methane functionalization;
- natural gas;
- chain reaction;
- coordination catalysts;
- oxidant activation