Thermodynamic Limitations of the Catalyst Design Space for Methanol Production from Methane

Current efforts to overcome the challenges of direct methane to methanol processes have focused on designing heterogeneous catalysts that perform methane partial oxidation using cheap and abundant oxidants such as molecular oxygen and water. An evaluation of the thermodynamic limitations of methanol production with the use of these oxidants is required to understand the maximum possible conversion and selectivity for a given feed composition and temperature. When O-2 is present, the formation of the most thermodynamically stable product, carbon dioxide, must be inhibited. At practical temperatures for moderate scale processes, water as the sole oxidant results in extremely low steady-state methane conversion, but higher yields can be achieved with coupled surface reactions. This work evaluates these thermodynamic challenges and opportunities for catalysts that can selectively oxidize methane to methanol with oxygen and water and discusses routes for achieving high methanol yields.