Methanol, also known as methyl alcohol amongst other names, is a chemical with the formula CH₃OH (a methyl group linked to a hydroxyl group, often abbreviated MeOH). It is a light, volatile, colourless, flammable liquid with a distinctive alcoholic odour similar to that of ethanol.  A polar solvent, methanol acquired the name wood alcohol because it was once produced chiefly by the destructive distillation of wood. Today, methanol is mainly produced industrially by hydrogenation of carbon monoxide.

Methanol consists of a methyl group linked to a hydroxyl group. With more than 20 million tons produced annually, it is used as a precursor to other commodity chemicals, including formaldehyde, acetic acid, methyl tert-butyl ether, as well as a host of more specialised chemicals.

Applications

Methanol to hydrocarbons, olefins, gasoline

Condensation of methanol to produce hydrocarbons and even aromatic systems is the basis of several technologies related to gas to liquids. These include methanol-to-hydrocarbons (MTH), methanol to gasoline (MTG), and methanol to olefins (MTO), and methanol to propylene (MTP). These conversions are catalyzed by zeolites as heterogeneous catalysts. The MTG process was once commercialized at Motunui in New Zealand.

Gasoline additive

The European Fuel Quality Directive allows fuel producers to blend up to 3% methanol, with an equal amount of cosolvent, with gasoline sold in Europe. China uses more than 4.5 billion liters of methanol per year as a transportation fuel in low level blends for conventional vehicles, and high level blends in vehicles designed for methanol fuels.

Other chemicals

Methanol is the precursor to most simple methylamines, methyl halides, and methyl ethers. Methyl esters are produced from methanol, including the transesterification of fats and production of biodiesel via transesterification.

Niche and potential uses

Energy carrier

Methanol is a promising energy carrier because, as a liquid, it is easier to store than hydrogen and natural gas. Its energy density is however low reflecting the fact that it represents partially combusted methane. Its energy density is 15.6 MJ/L, whereas ethanol's is 24 and gasoline's is 33 MJ/L.

Further advantages for methanol is its ready biodegradability and low toxicity. It does not persist in either aerobic (oxygen-present) or anaerobic (oxygen-absent) environments. The half-life for methanol in groundwater is just one to seven days, while many common gasoline components have half-lives in the hundreds of days (such as benzene at 10–730 days). Since methanol is miscible with water and biodegradable, it is unlikely to accumulate in groundwater, surface water, air or soil.

Fuel for vehicles

Methanol is occasionally used to fuel internal combustion engines. It burns forming carbon dioxide and water:

2 CH₃OH + 3 O₂ → 2 CO₂ + 4 H₂O

One problem with high concentrations of methanol in fuel is that alcohols corrode some metals, particularly aluminium. Methanol fuel has been proposed for ground transportation. The chief advantage of a methanol economy is that it could be adapted to gasoline internal combustion engines with minimum modification to the engines and to the infrastructure that delivers and stores liquid fuel. Its energy density is however only half that of gasoline, meaning that twice the volume of methanol would be required.

Other applications

Methanol was used as a denaturant (intentional toxin) for ethanol, the product being known as "denatured alcohol" or "methylated spirit". This was commonly used during the Prohibition to discourage consumption of bootlegged liquor, and ended up causing several deaths.^[46] These types of practices are illegal in modern times, being considered homicide. 

Methanol is used as a solvent and as an antifreeze in pipelines and windshield washer fluid. Methanol was used as an automobile coolant antifreeze in the early 1900s. As of May 2019, methanol was banned in the EU for use in windscreen washing or defrosting due to its risk of human consumption.

In some wastewater treatment plants, a small amount of methanol is added to wastewater to provide a carbon food source for the denitrifying bacteria, which convert nitrates to nitrogen gas and reduce the nitrification of sensitive aquifers.

Methanol is used as a destaining agent in polyacrylamide gel electrophoresis.

Direct-methanol fuel cells are unique in their low temperature, atmospheric pressure operation, which lets them be greatly miniaturized.This, combined with the relatively easy and safe storage and handling of methanol, may open the possibility of fuel cell-powered consumer electronics, such as laptop computers and mobile phones.

Methanol is also a widely used fuel in camping and boating stoves. Methanol burns well in an unpressurized burner, so alcohol stoves are often very simple, sometimes little more than a cup to hold fuel. This lack of complexity makes them a favorite of hikers who spend extended time in the wilderness. Similarly, the alcohol can be gelled to reduce risk of leaking or spilling, as with the brand "Sterno".

Methanol is mixed with water and injected into high performance diesel and gasoline engines for an increase of power and a decrease in intake air temperature in a process known as water methanol injection.

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