Acetic Acid Synthesis via Methanol Carbonylation

methanol carbonylation is the favored way for manufacturing acetic acid. The route is claimed to have the lowest production costs, especially for large-scale production. In general, the production costs of commodity chemicals are dominated by the raw material costs. In fact, methanol produced from synthesis gas (mainly from natural gas) is nowadays a cheap starting material. In 2006, processes based on methanol carbonylation accounted for about 78% of the world capacity for acetic acid. 

Methanol carbonylation is an exothermic reaction and shows a volume decrease. Thus, the reaction is favored by low temperatures and high pressures [Eq. (6.15.3)]  

However, the yield based on CO is usually much lower in carbonylation processes, due to a competing water gas shift reaction that converts CO and water into CO2 and hydrogen  

Water is added to the reaction system to suppress the undesired formation of methyl acetate [Eq. (6.15.5)] and dimethyl ether [Eq. (6.15.6)] during the reaction. In this way the acetic acid yield with respect to methanol is increased  

The following subsections discuss the three most important carbonylation processes in more detail. 

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