Methanol is a liquid petrochemical made up of four parts hydrogen, one part oxygen, and one part carbon (CH3OH) manufactured commercially from natural gas. Methanol is a common laboratory solvent. It is especially useful for HPLC and UV/VIS spectroscopy due to its low UV cutoff.
By far, the largest use of methanol is in manufacture of other chemicals. Approximately 40 percent of methanol is converted to formaldehyde. It is then used to make other products as diverse as plastics, plywood, paints, explosives, and permanent press textiles.
In the early 1970s, Mobil developed a methanol to gasoline process for producing vehicle ready gasoline. One of the facilities was built in New Zealand at Motunui in the 1980s. Then in the 1990s, the United States used large amounts of methanol to produce the gasoline additive methyl tert-butyl ether (MTBE). MTBE was taken off the market in the US, it is still widely used in other parts of the world. In addition to direct use as a fuel, methanol is a component in the transesterification of triglycerides to yield a form of biodeisel.
Other chemical derivatives of methanol include dimethyl ether, which has replaced chlorofluorocarbons as an aerosol spray propellant, and acetic acid. Dimethyl ether or “DME” also can be blended with liquefied petroleum gas (LPG) for home heating and cooking, and can be used as a diesel replacement transportation fuel.
Fuel for vehicles
Methanol is used to fuel internal combustion engines on a limited basis, primarily because it is not nearly as flammable as gasoline. Methanol is more difficult to ignite than gasoline and produces just one-eighth of the heat. Many racing classes including drag racers and mud racers use methanol as their primary fuel source. Methanol is required with a supercharged engine in a Top Alcohol Dragster and, until the end of 2006, all vehicles in the Indianapolis 500 had to run methanol. Mud racers have mixed methanol with gasoline and nitrous oxide to produce more power than gasoline and nitrous oxide alone.
One of the drawbacks of methanol as a fuel is its corrosivity to some metals, including aluminium. Methanol, although a weak acid, attacks the oxide coating that normally protects the aluminium from corrosion:
6 CH3OH + Al2O3 → 2 Al(OCH3)3 + 3 H2O
The resulting methoxide salts are soluble in methanol, resulting in clean aluminium surface, which is readily oxidized by some dissolved oxygen. Also the methanol can act as an oxidizer:
6 CH3OH + 2 Al → 2 Al(OCH3)3 + 3 H2
This reciprocal process effectively fuels corrosion until either the metal is eaten away or the concentration of CH3OH is negligible. Concerns with methanol’s corrosivity have been addressed by using methanol compatible materials, and fuel additives that serve as corrosion inhibitors.
When produced from wood or other organic materials, the resulting organic methanol (bioalcohol) has been suggested as renewable alternative to petroleum-based hydrocarbons. Low levels of methanol can be used in existing vehicles, with the use of proper cosolvents and corrosion inhibitors. The European Fuel Quality Directive allows up to 3 percent methanol with an equal amount of cosolvent to be blended in gasoline sold in Europe. Today, China uses more than one billion gallons of methanol per year as a transportation fuel in both low level blends in existing vehicles, and as high level blends in vehicles designed to accommodate the use of methanol fuels.
Methanol is a traditional denaturant for ethanol, thus giving the term “methylated spirit.”
Methanol is also used as a solvent, and as an antifreeze in pipelines and windshield washer fluid.
In some wastewater treatment plants, a small amount of methanol is added to wastewater to provide a food source of carbon for the denitrifying bacteria, which convert nitrates to nitrogen to reduce the denitrification of sensitive aquifers.
During World War II, methanol was used as a fuel in several German military rocket designs, under the name M-Stoff, and in a mixture as C-Stoff.
In the early 1900s, methanol was used as an automobile coolant antifreeze.
Methanol is also a denaturing agent in polyacrylamide gel electrophoresis.
Direct-methanol fuel cells are unique in their low temperature, atmospheric pressure operation, allowing them to be miniaturized to an unprecedented degree. Combined with the relatively easy and safe storage and handling of methanol, this may open the possibility of fuel cell-powered consumer electronics, such as laptop computers and mobile phones.
Methanol is also widely used as fuel in camping and boating stoves. Methanol burns well in unpressurized burners. Alcohol stoves often require little more than a cup to hold fuel. This lack of complexity makes them a favorite of hikers spending extended time in the wilderness.