Introduction to Methanol Synthesis and Steam Reforming

This chapter focuses on the catalytic aspects of methanol chemistry and covers thermodynamic, kinetic, chemical engineering, and materials science aspects. It provides brief introductions into these topics with the aim of establishing an overview of the state of the art of methanol chemistry with only a snapshot of the relevant literature. It highlights what the authors think are the most relevant aspects and future challenges for energy-related catalytic reactions of methanol. It is not meant to provide a complete literature overview on methanol synthesis and reforming. 

The current primary feedstock for industrial methanol synthesis is synthesis gas a mixture of CO, C02 and hydrogen derived from the reforming of natural gas or other hydrocarbons [2], The interconversion of carbon oxides and methanol, central to methanol synthesis and steam reforming, is defined by the following three equilibrium equations  

Methanol synthesis from C02 (Equation [1]) and CO (Equation [2]) is mildly exothermic and results in volumetric contraction. Methanol steam reforming (MSR) refers to the inverse of reaction (1), and the inverse of reaction (2) is conventionally referred to as methanol decomposition - an undesired side reaction to MSR. The slightly endothermic reverse water-gas shift (rWGS) reaction (Equation [3]) occurs as a side reaction to methanol synthesis and MSR. According to Le Chatelier s principle, high pressures and low temperatures would favor methanol synthesis, whereas the opposite set of conditions would favor MSR and methanol decomposition. It should be noted that any two of the three reactions are linearly independent and therefore sufficient in describing the compositions of equilibrated mixtures. 

MSR is also carried out on methanol synthesis catalysts at similar temperatures (see Section 5.3.7), but unlike methanol synthesis, it is not subject to thermodynamic constraints. Thermodynamic considerations play a lesser role in MSR, as the inverse of reactions (1) and (2) can be considered irreversible at atmospheric pressure. 

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