Chemistry: What Is Methanol?

Methanol(CH₃OH) is a simple compound which is also known as methyl alcohol or wood alcohol.Methanol is colourless,flammable and most importantly very toxic.They are naturally produced from volcanic gases,vegetation and microbes.They can also be produced in the industry by synthesizing gas.The largest and the most important use of methanol is as a feedstock in the plastic industry.They are used to make methanal and hence variety of plastics,based on reactions with phenol,carbamide(urea) and melamine.

Methanol synthesises with synthesis gas

CO + 2H2 ⇌ CH3OH ΔH298K = -21.7 kcal/mol (1) CO2 + 3H2 ⇌ CH3OH + H2O ΔH298K = -11.9 kcal/mol (2)
Reverse WGS CO2 +
To synthesise methanol, not only is a specific H2/CO ratio of 2 in the synthesised gas needed but also a (H2-CO2)/(CO+CO2) ratio, called stoichiometric number, equal to or slightly above 2
The synthesis gas produced have a lack of hydrogen and must be subjected to the water gas shift reaction (equation 3) to improve the H2/CO ratio. The synthesis gas produced from coal is normally in higher need of purification than that produced from natural gas, especially sulphur compounds must be removed before the methanol synthesis to protect the catalysts from poisoning.

Methanol purification

Regardless of the synthesis method the crude methanol produced contains many impurities.The largest impurity is normally water which can be a high as 18 %. The first stage in a common two-step purification process is to remove the low boiling purifications, typically called “light ends”. This is done in a “topping column” where the low boiling compounds are boiled off to produce a mixture of methanol and water.A refining column is used to separate water and methanol under heavy boiling. The refining column needs to be high as methanol and water is reluctant to separate easily. Greater quality methanol eventually accumulates at the top of the column and is then transferred to a storage tank. Water accumulates in the bottom and taken to a