Dr.Mohammed Saleh Al.Ansari

syngas required for methanol synthesis

May 27, 2010

I apprehend that the stoichiometric number of the syngas required for methanol synthesis is frequently defined as (H2-CO2)/(CO+CO2), and most likely it is at 2. To arrive to this statement I worked it out  assuming it is related to the stoichiometric molar balance in two parallel reactions of hydrogen with carbon oxides:
                                             CO + 2 H2 => CH3OH
Stoichiometrically 2 moles of hydrogen react with 1 mole of CO to produce 1 mole of methanol. The xs hydrogen from syngas (as I got it from methane reforming) is reacted with CO2. In this reaction 3 moles of hydrogen react with 1 mole of carbon dioxide to produce 1 mole of methanol and 1 mole of water.
                                           CO2 + 3 H2 => CH3OH + H2O
Combining and managing both reactions it can be seen that 5 moles of hydrogen react with 1 mole of CO and 1 mole of CO2. Therefore, moles of hydrogen less moles of CO, divided by the sum of the moles of both carbon oxides is 2. I put into practice this number is adjusted by addition of hydrogen or CO2 as needed.

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